JP3688601B2 - Liquid crystal display device and projection display device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video signal display method suitable for a matrix type display device in which pixels are arranged in a matrix type in the line and row directions. The present invention also provides a display device (hereinafter referred to as a projection display device) that enlarges and projects an image displayed on a small liquid crystal display device on a screen, and a display device (hereinafter referred to as a viewfinder) that is used as a video camera shooting monitor. And a display device used as a light valve for a projection display device and a viewfinder.
[0002]
[Prior art]
Since liquid crystal display devices have many features such as light weight and thinness, research and development are active. However, there are many problems such as difficulty in increasing the screen size. Therefore, in recent years, a projection type display device that obtains a large screen display image by enlarging and projecting a display screen of a small liquid crystal device with a projection lens or the like has attracted some attention. Currently, commercially available projection display devices use twisted nematic (hereinafter referred to as TN) liquid crystal display devices utilizing the optical rotation characteristics of liquid crystals. Active matrix liquid crystal display devices have been increased in density and the number of pixels has been increasing, and are used as data display displays for personal computers and workstations, and as standard (NTSC) and HDTV AV displays. .
[0003]
Further, with the increase in the number of pixels of the active matrix type liquid crystal display device, it has been required to increase the operation clock of the source driving (data line driving) IC. Therefore, not only the development of a source drive IC with a high-speed operation clock, but also a method of driving a plurality of source drive ICs in parallel and simultaneously driving a plurality of divided screen area source lines as a drive method. . Since the conventional display device is a TN liquid crystal display device and is very general, the description thereof is omitted here, and for the convenience of explaining the video signal display method of the present invention, the conventional active matrix liquid crystal display device is not described. A specific example of the display driving method will be described.
[0004]
FIG. 101 shows a video signal processing circuit of a conventional active matrix type liquid crystal display device. The video signal processing circuit includes an A / D converter 71, memories 72 and 73, D / A converters 74 and 75, source signal processing circuits 76 and 77, an active matrix liquid crystal display panel (hereinafter referred to as a liquid crystal display). A gate drive IC 80 for driving the gate line xi (i = 1 to n) of 81 (which may be abbreviated as a panel) and two source drives for driving the source line yj (j = 1 to 2 m) of the liquid crystal display panel 81 ICs 78 and 79 are provided. The source drive ICs 78 and 79 include m-bit shift registers 82 and 83 and sample and hold circuit groups 84 and 85, respectively. Each sample hold circuit group 84, 85 has m sample hold circuits. The liquid crystal display panel 81 has a plurality of pixels arranged in a matrix. Each pixel includes a thin film transistor (hereinafter referred to as TFT) 86 as a switching element and a liquid crystal layer 87. The source of the TFT 86 is connected to the source line yj of the corresponding column, and the gate is connected to the gate line xi of the corresponding row. The liquid crystal layer 87 has one electrode in contact with the drain of the corresponding TFT 86 and the other in contact with the counter electrode 88. The memories 72 and 73 are random access memories, and have a function of extending the video signal to the time axis twice. In the above configuration, the source driving IC is divided into two. However, when a larger liquid crystal display panel is driven for display, the source driving IC may be divided into three or more.
[0005]
The operation of the video signal processing circuit of this conventional active matrix liquid crystal display device will be described below. First, the input video signal is converted into a digital video signal by the A / D converter 71 and stored in the memories 72 and 73. The memory 72 extends the video signal input to the source lines y1 to ym of the liquid crystal display panel 81, that is, the video signal of the first half of the video signal of one scanning line by a time axis. The digital video signal whose time axis has been expanded twice in the memory 72 is converted into an analog video signal by the D / A converter 74. Next, the source signal processing circuit 76 performs γ correction on the analog video signal whose time axis has been doubled, and inverts the polarity of the analog video signal for each frame in order to drive the liquid crystal display panel 81 with AC. . An output signal of the source signal processing circuit 76 is input to the source driving IC 78. On the other hand, the memory 73 extends the video signal input to the source lines ym + 1 to y2m of the liquid crystal display panel 81, that is, the video signal of the latter half of the video signals of one scanning line by a time axis. The digital video signal whose time axis has been expanded twice in the memory 73 is converted into an analog video signal by the D / A converter 75. Next, the source signal processing circuit 77 performs γ correction on the analog video signal whose time axis has been doubled, and inverts the polarity of the analog video signal for each frame in order to drive the liquid crystal display panel 81 with AC. . An output signal of the source signal processing circuit 77 is input to the source driving IC 79. In the source drive ICs 78 and 79, the video signals input from the source signal processing circuits 76 and 77 are given in parallel to the sample and hold circuits of the sample and hold circuit groups 84 and 85, respectively. Each sample and hold circuit of the sample and hold circuit group 84 sequentially holds video signals input to the source lines y1 to ym in synchronization with the shift operation of the shift register 82. Similarly, each sample and hold circuit of the sample and hold circuit group 85 sequentially holds video signals input to the source lines ym + 1 to y2m in synchronization with the shift operation of the shift register 83. When the gate line xi is activated by the gate driving IC 80 and each TFT 86 in the i-th row is turned on, the video data for one scanning line held in each sample hold circuit of the sample hold circuit groups 84 and 85 is source lines y1 to y2m. And applied to each liquid crystal layer 87 in the i-th row. As a result, video data for one scanning line is written in the liquid crystal display panel 81. While repeating the above source driving operation and the gate driving IC 80 sequentially scans the gate lines, an image is obtained on the liquid crystal display panel 81.
[0006]
However, in the configuration as described above, the difference in luminance due to the variation in the analog circuit after the D / A converter at the joint between adjacent source drive ICs and the difference in holding time in each sample hold circuit inside the source drive IC. Occurs and the image quality deteriorates. In order to solve the above problems, a method of adding a correction circuit for correcting a luminance difference and a method of using a source drive IC as a digital input can be considered. However, the cost increase, the circuit scale, and the mounting area around the liquid crystal display panel Accompanied by an increase. Conventionally, a plurality of source drive circuits are formed on a silicon substrate using semiconductor technology, and each source drive circuit is cut out and used as source drive ICs 78 and 79. Since the IC operates at a considerably high speed, the number of screen divisions can be two or three.
[0007]
In recent years, a technology (low-temperature polysilicon technology) has been established in which an amorphous silicon film or the like is deposited on a glass substrate, a semiconductor layer is formed by crystallization using a laser or the like, and a TFT 86 is formed using the semiconductor layer. However, liquid crystal display panels using the above technology are attracting attention because they can be manufactured at low cost, and prototypes have been announced and developed by various companies. In addition, a technique (high temperature polysilicon technique) for forming a TFT 86 by forming a silicon crystal film on a quartz glass substrate has been established. The liquid crystal display panel using the polysilicon technology is expensive and difficult to form a display area having a large area, but has been put to practical use in a viewfinder such as a video camera.
[0008]
A feature common to liquid crystal display panels manufactured by high-temperature polysilicon technology and low-temperature polysilicon technology is that the gate drive IC 80 and the source drive IC 82 can be formed on the same substrate as the TFT 86 at the same time. Therefore, it is not necessary to mount the gate drive IC 80 and the source drive IC 82 on the panel 81 after the liquid crystal display panel 81 is manufactured. Further, it is not necessary to newly manufacture the source drive IC 82 and the like. Therefore, the cost can be reduced in that the mounting cost can be reduced.
[0009]
[Problems to be solved by the invention]
The problem of the liquid crystal display panel manufactured by the polysilicon technology is that the upper limit operation speed of the source drive circuit or the like directly formed on the liquid crystal display panel 81 is low. In general, the range of stable operation is 1 MHz to 3 MHz. Therefore, it is necessary to deal with the shift register 82 of the source drive circuit in multiple stages. If the operating frequency of the shift register is 2 MHz and the liquid crystal display panel needs to be operated at 40 MHz, it is necessary to divide 40/2 = 20. That is, it is necessary to form 20 shift registers. As the number of shift registers increases, the area occupied by the shift registers increases, and the number of defects in the process increases, which is not preferable.
[0010]
As described above, a liquid crystal display panel formed by polysilicon technology, particularly low-temperature polysilicon technology, has the advantage that it is highly possible to reduce the price, and is promising as a display monitor for future personal computers and workstations. However, on the other hand, there is an aspect that it is difficult to achieve high speed driving (high speed data rate = broadband).
[0011]
NTSC and HD are interlaced scanning video signals. VGA and SXGA are progressive scanning video signals. As long as it is compatible with NTSC and HD as a home TV, it is sufficient for the time being. However, there is a strong demand for displaying SXGA. However, in order to apply the liquid crystal display panel to a progressive scanning video signal, the number of parallel shift registers is twice that of an interlace scanning video signal. Therefore, in order to apply to progressive scanning video signals of SXGA, it is not required in the HD standard. Further, it is necessary to previously form a shift register formed in parallel twice. This is too lossy. In general, wideband (high-speed data rate) progressive scanning video signals from personal computers and workstations can be easily and inexpensively displayed on high-speed scanning displays such as matrix-type liquid crystal display panels consisting of lines and columns. It is desired to display without causing deterioration.
[0012]
A liquid crystal display device is used as such a matrix display. However, the commonly used TN liquid crystal display panel has the following problems. In this display panel, the liquid crystal molecules change the alignment direction according to the applied voltage. The orientation changes according to the video signal, and the light passing through the liquid crystal layer is modulated. However, the TN liquid crystal panel needs to use a polarizer, has a low overall light transmittance, and cannot display with high brightness. Further, due to the heat absorbed by the polarizer, the polarizer itself and the liquid crystal display panel become high temperature, and it is easy to cause significant performance deterioration in a short time.
[0013]
An object of the present invention is to display a wide-band (high-speed data rate) progressive scanning video signal on a display device that is not good at high-speed scanning easily and inexpensively without causing deterioration in image quality.
[0014]
[Means for Solving the Problems]
The liquid crystal display device according to the present invention includes pixels arranged in a matrix, source signal lines that transmit video signals to the pixels, and source driver circuits that apply video signals to the source signal lines. Here, in the first liquid crystal display device, the source driver circuit has a first polarity video signal and a polarity opposite to the first polarity for each of a predetermined number of the plurality of pixel rows in the first frame or field. The video signal is output so that the video signal of the second polarity is alternately held in the pixel. The source driver circuit outputs a video signal so as to hold a video signal having a polarity opposite to that of the video signal held in the pixel row in a second frame or field next to the first frame or field. To do.
[0023]
[Means for Solving the Problems]
The liquid crystal display device according to the present invention is Arranged in a matrix plural Pixels, A counter electrode facing the plurality of pixels; Connected for each pixel Connected to the switching elements and the switching elements of the plurality of pixels arranged in the line direction of the matrix, and connected to the switching elements A source signal line for transmitting a video signal to the pixel; A gate signal line connected to the switching elements of the plurality of pixels arranged in a direction orthogonal to the line direction of the matrix, and controlling the pixels connected to the switching elements; A source for applying a video signal to the source signal line Drive Circuit, A gate drive circuit for applying a gate drive signal to the gate signal line; Comprising the source Drive Circuit held in pixel Voltage against the potential of the counter electrode When changing the polarity, Said With the same polarity, When the polarity of the same input video signal is changed, it is output compared to the case where the polarity is the same. Increase the size of the video signal Do .
[0024]
Preferably, said of The liquid crystal display device further includes a first gate driver circuit and a second gate driver circuit. The first gate signal line for controlling the odd-numbered pixel rows is connected to the first gate driver circuit, and the second gate signal line for controlling the even-numbered pixel rows is connected to the second gate driver circuit. Is done.
[0025]
Preferably, in any of the liquid crystal display devices described above, the image display position can be moved within the display area.
[0026]
Preferably, in any one of the liquid crystal display devices described above, the source driver circuit includes the first source driver circuit and the second source driver circuit, and applies the video signal to the odd pixel columns. The signal line is connected to the first source driver circuit, and the second source signal line for applying the video signal to the even pixel row is connected to the second source driver circuit.
[0027]
Preferably, in any of the liquid crystal display devices described above, dielectric pillars that substantially match the liquid crystal layer are formed or disposed on or between the pixels arranged in a matrix.
[0028]
Preferably, in any of the above-described liquid crystal display devices, a retardation film or a retardation plate is disposed or formed on the light incident side or the light emitting side to the liquid crystal layer.
[0029]
A projection display device according to the present invention includes light generation means, any one of the liquid crystal display devices described above, and a projection lens. The liquid crystal display device modulates the light emitted by the light generating means, and the projection lens projects the light modulated by the liquid crystal display device.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
First, a video signal display method according to an embodiment of the present invention will be described with reference to the drawings. Here, the same reference symbols in the drawings denote the same.
In the present invention, the first and second display methods different from each other are executed individually or selectively. FIG. 1 shows a display image on the display for explaining the first display method, and FIG. 2 shows a display image on the display for explaining the second display method.
[0031]
The progressive scanning video signal forms one screen in one field. Therefore, 1 field = 1 frame. On the other hand, the interlace signal forms one screen with two fields. Therefore, 2 fields = 1 frame. In the following description, the field and the frame are basically used properly, but depending on the content of the description, the field and the frame are treated as synonymous.
[0032]
First, the first display method will be described. In FIG. 1, (a) shows an image when the first frame of the input progressive scan video signal is displayed on the display as it is, and (b) shows the second frame of the input progressive scan video signal on the display. Shows an image displayed as it is. The first and second frames are temporally continuous frames. As shown in (c), first, the first line of the first frame of the progressive scan video signal that has been input (1_1 line, hereinafter denoted in the same manner) is selected, and the time axis is expanded twice to display Display in the first line above. Next, the third line of the first frame is selected, and the time axis is doubled and displayed on the third line on the display. Hereinafter, only the odd lines of the first frame, such as the fifth line, the seventh line,... Are sequentially selected, and the time axis is doubled and displayed on the odd lines on the display. On the other hand, in the second frame, only even lines are sequentially selected, and the time axis is doubled and displayed on the even lines on the display. As a result, one frame composed of the odd lines of the first frame and the even lines of the second frame as shown in (c) is displayed. The above operation is similarly applied to the third frame and the fourth frame, and is repeated thereafter.
[0033]
As described above, since it is sufficient to display one frame including the odd lines of the first frame and the even lines of the second frame in the two frame periods of the input progressive scan video signal, the input progressive scan is performed. The video signal can be displayed at half the speed compared to when it is displayed as it is. This means that the liquid crystal display panel 81 does not need to be divided and driven with respect to FIG. Therefore, the occurrence of a luminance difference can be prevented. Further, when the source drive IC 78 or the like is formed directly on the liquid crystal display panel 81 by the polysilicon technique, the clock frequency of the shift register 82 or the like can be reduced to ½.
[0034]
For example, when the frequency of the video signal is 40 MHz and the operating frequency of the shift register is 4 MHz, the number of shift registers formed in parallel is reduced by 10 shift registers formed in parallel. The 40 MHz video signal sample-hold can be performed. Therefore, if the clock of the shift register can be reduced to ½ by the implementation of the present invention, it can be handled by five shift registers formed in parallel. If the number of shift registers formed in parallel can be halved, the occurrence of defects such as shift registers is reduced, and the yield of display panel formation is improved. Moreover, since it can be operated at a speed of 1/2, power consumption can be greatly reduced.
[0035]
The odd lines of the liquid crystal display panel 81 are displayed in the first frame, and the even lines of the liquid crystal display panel 81 are displayed in the second frame, but this is merely for convenience of explanation. Accordingly, when the first frame of the progressive scanning video signal is data of even lines, the even lines of the liquid crystal display panel are naturally displayed. Further, although the first frame is displayed from the first line, the present invention is not limited to this. The first line is merely for convenience of explanation. For example, you may display from the 7th line. The first line is merely provided for ease of explanation. In the case described above, the first to sixth lines are displayed in black. The above description applies also to the video display method and display device described in the specification and claims of the present invention.
[0036]
In FIG. 101, the concept of the source driving IC 78 or the gate driving IC 80 is used. However, the present invention relates to an invention such as a display method, and is not limited to a display device mounted with an IC. Therefore, hereinafter, the terms “source drive circuit” and “gate drive circuit” are used as a concept including a drive circuit formed by polysilicon technology.
[0037]
Next, the second display method will be described. In FIG. 2, (a) shows an image when the first frame of the input progressive scan video signal is displayed on the display as it is, and (b) shows the second frame of the input progressive scan video signal on the display. Shows an image displayed as it is. First, the first line of the first frame of the input progressive scanning video signal is selected, and the time axis is expanded by a factor of 2 and is simultaneously displayed on the first and second lines on the display. Next, the third line of the first frame is selected, and the time axis is expanded by a factor of 2 and is simultaneously displayed on the third and fourth lines on the display. Thereafter, only the odd lines of the first frame, such as the fifth line, the seventh line,... Are sequentially selected, and the time axis is doubled to display them simultaneously on the odd lines and the adjacent even lines on the display. As a result, the image shown in (b) is obtained. On the other hand, in the second frame, only even lines are sequentially selected, and the time axis is doubled and displayed simultaneously on the even lines and adjacent odd lines on the display. As a result, the image shown in (c) is obtained. The above operation is similarly applied to the third frame and the fourth frame, and is repeated thereafter. As described above, since it is sufficient to display one frame composed of the odd-numbered lines of the first frame and the even-numbered lines of the second frame in the two-line period of the input progressive-scanned video signal, the input progressive-scanned video signal Can be displayed at a speed half that of when displaying as it is.
[0038]
While the two display methods have been described above, it is preferable to select the first display method for a still image and the second display method for a moving image. Since the still image is stopped, the image discontinuity in the vertical direction is more visible than the moving image. Therefore, in the case of a still image, it is preferable to ensure an apparent vertical resolution by performing interpolation between frames by the first display method. On the other hand, since the temporal change of the moving image is severe, when the first display method is applied, so-called moving image blurring (jerkinness interference or the like) occurs. Therefore, in the case of a moving image, it is preferable to prevent the occurrence of moving image blur by performing interpolation within the frame by the second method. A circuit configuration for switching between the first display method and the second display method will be described later with reference to FIG.
[0039]
In the first display method, when the display time (light emission time) is as short as several milliseconds to several tens of milliseconds as in the case of a CRT display, for example, when the frame period of the input progressive video signal is 60 Hz, the same line The emergency period becomes 30 Hz and flicker occurs. However, in a display that maintains a display state until refreshing, such as an active matrix liquid crystal display, scanning line interpolation is completely performed. In addition, the second display method is to use a multi-gun configuration for an electron gun in a CRT display (preparing two electron guns, for example), and to activate two gate lines simultaneously in an active matrix liquid crystal display. It can be easily realized.
[0040]
The video signal display method of the present invention will be described in detail later. First, a video signal display apparatus according to an embodiment of the present invention will be described with reference to the drawings. This is because the video signal display method of the present invention is closely related to the display device of the present invention, and it is easier to understand the operation of the display device, such as the voltage polarity applied to the pixel electrode. It is possible.
[0041]
FIG. 3 shows a video signal display apparatus according to an embodiment of the present invention. In FIG. 3, a video signal display device converts a video signal into a signal suitable for liquid crystal driving by performing display line selection circuit 31 for selecting a display line and extending the time axis of the video signal, and mainly performing γ correction and AC conversion. A source signal processing circuit 32, a liquid crystal display panel 81 in which a plurality of pixels are arranged in a matrix, a source drive circuit 33 that is connected to a source line of the liquid crystal display panel 81 and applies a voltage to the liquid crystal 87, and a horizontal start pulse From gate drive circuit control circuits 36 and 37 that generate gate drive circuit control signals (GCK1, GCK2, GST1, GST2, GEN1, and GEN2) in response to HD and vertical start pulse VD, and gate drive circuit control circuits 36 and 37 Depending on the gate drive circuit 38 whose operation is controlled based on the gate drive circuit control signal and the nature of the image (still image or moving image) A display method selection circuit 35 for selecting one of the gate drive circuit control circuits 36 and 37 and an output of the gate drive circuit control circuits 36 and 37 are selectively switched in response to a switching signal from the display method selection circuit 35. And a switch 44 for outputting to the gate drive circuit 38. The display line selection circuit 31 responds to the A / D converter 40, the line memory 41 for storing the image signal for one scanning line, the D / A converter 42, and the horizontal start pulse HD and the vertical start pulse VD. And a line memory control circuit 43 for controlling the operation of the line memory 41 that has generated the memory control signals (WCK, WEN, RCK). The source drive circuit 33 includes a 2m-bit shift register and a sample and hold circuit group having 2m sample and hold circuits. The gate drive circuits 38a and 38b are circuits having the same configuration and function as each other. However, the first gate driving circuit 38a is connected to the odd-numbered gate lines of the liquid crystal display panel 81 and sequentially activates the odd-numbered gate lines. The second gate drive circuit 38b is connected to the even-numbered gate lines of the liquid crystal display panel 81 and sequentially activates the even-numbered gate lines.
[0042]
FIG. 4 shows a more detailed configuration of the gate drive circuit 38. In FIG. 4, the gate drive circuit 38 includes an n / 2-bit shift register 91 (n is the number of gate lines of the liquid crystal display panel 81), a changeover switch group 92 having n / 2 changeover switches 96, n / An output buffer group 93 having two output buffers 97 is provided. The shift register 91 includes n / 2 D-type flip-flops 94 and one inverter 95.
[0043]
The start signal GST1 (or GST2) is applied to the data input terminal D of the first D-type flip-flop 94, and after the polarity is inverted by the inverter 95, the second and subsequent D-type flip-flops 94 It is given to the clear terminal C.
[0044]
The clock signal GCK1 (or GCK2) is applied to the clock terminal CK of each D-type flip-flop 94. Further, the Q output of the preceding D-type flip-flop 94 is given to the data input terminal D of each of the second and subsequent D-type flip-flops 94. In the shift register 91 having the above-described configuration, the Q output of the k-th (k = 1 to n / 2) D-type flip-flop 94 is taken out as a k-th signal, and the k in the changeover switch group 92 is extracted. This is given to the A terminal of the individual changeover switch 96.
[0045]
The B terminal of each changeover switch 96 is grounded. The output terminal C of each changeover switch 96 is connected to the A terminal when the enable signal GEN1 (or GEN2) is at a high level, and is connected to the B terminal when it is at a low level. A signal output from the output terminal C of each changeover switch 96 is applied to each output pin 98 via a corresponding output buffer 97 in the output buffer group 93. Each output pin 98 is connected to a corresponding gate line of the liquid crystal display panel 81.
[0046]
The operation of the video signal display apparatus configured as described above will be described below. FIG. 5 shows a timing chart of memory control signals input to the line memory 41 and input / output video signals of the line memory 41. First, the source line drive control operation will be described with reference to FIG. The progressive scan video signal input to the display line selection circuit 31 is first converted into a digital video signal by the A / D converter 40. The line memory 41 captures the progressive scan video signal at a timing synchronized with the write clock signal WCK while the write enable signal WEN is at a high level. (In the figure, for example, the signal 1_2_3 represents the third signal of the 1_2 line.) That is, the first line of the first frame is captured in synchronization with the write clock signal WCK because the write enable signal WEN is at a high level. The second line of the first frame is not captured because the write enable signal WEN is low.
[0047]
By repeating the above operation, odd lines of the first frame are sequentially taken into the line memory 41. Similarly, the first line of the second frame is not captured because the write enable signal WEN is low, and the second line of the second frame is captured in synchronization with the write clock signal WCK because the write enable signal WEN is high. . By repeating the above operation, the even lines of the second frame are sequentially taken into the line memory 41. Further, by repeating the above operations in units of frames, odd lines of odd frames and even lines of even frames are sequentially taken into the line memory 41. The digital video signal taken into the line memory 41 is read out in synchronization with the read clock signal RCK, which is a half frequency of the write clock signal WCK.
[0048]
The signal output from the line memory is a digital video signal obtained by expanding the odd-numbered odd-numbered frame and the even-numbered even-numbered line of the captured progressive scan video signal by a time axis. Converted to video signal.
[0049]
Next, the source signal processing circuit 32 performs γ correction on the progressive scanning video signal that has been line-selected and expanded in the time axis twice, and inverts the polarity for each frame to drive the liquid crystal display panel 81 with alternating current, Input to the drive circuit 33.
[0050]
The source drive circuit 33 sequentially writes and holds the input video signal to each sample hold circuit (not shown) in the IC. At this time, since the signal input to the source drive circuit 33 is a progressive scanning video signal that has been expanded in time base by a factor of 2, the write clock to each sample and hold circuit generated by a shift register (not shown) is also It may be ½ compared to the case where the time axis is not extended.
[0051]
When the gate line xi of the liquid crystal display panel 81 is activated by the gate driving circuit 38 and the TFT 86 is turned on, the video data held in each sample and hold circuit is applied to the liquid crystal cell 87 via the source line yj. As a result, a video signal for one scanning line is written on the liquid crystal display panel 81. An image is obtained on the liquid crystal display panel 81 by repeating the above operation and the gate drive circuit 38 scanning the gate line.
[0052]
Next, the drive control operation of the gate line will be described. The scanning of the gate line is determined by a gate drive circuit control signal (GCK1, GST1, GEN1 or GCK2, GST2, GEN2) output from the first gate drive circuit control circuit 36 or the second gate drive circuit control circuit 37. As described above, the gate drive circuits 38a and 38b are circuits having the same function, and sequentially and selectively activate the gate lines of the liquid crystal display panel 81 by the control of the gate drive circuit control signal.
[0053]
When the start signal GST1 (or GST2) is at a high level, the gate drive circuit 38 has an internal shift register 91 (see FIG. 4) at the rising edge of the clock signal GCK1 (or GCK2) (when it changes from a low level to a high level). Is reset, the first gate line is selected (retraced), and the second and third are sequentially selected each time the clock signal GCK1 (or GCK2) rises. When the enable signal GEN1 (or GEN2) is at a high level, a signal is output to the selected gate line to activate the gate line. As a result, the TFT 86 connected to the selected gate line is turned on. When the enable signal GEN1 (or GEN2) is at a low level, no signal is output to the selected gate line and it does not become active. Therefore, the TFT 86 connected to the gate line is in an off state. Here, the first gate drive circuit 38a is connected to the odd-numbered gate lines of the liquid crystal display panel 81, and the second gate drive circuit 38b is connected to the even-numbered gate lines.
[0054]
6 shows a timing chart of the gate drive circuit control signal output from the first gate drive circuit control circuit 36, and FIG. 7 shows the timing of the gate drive circuit control signal output from the second gate drive circuit control circuit 37. A chart is shown. Hereinafter, the gate line drive control operation will be described in more detail with reference to FIGS.
[0055]
In FIG. 6, a clock signal GCK1, a start signal GST1, and an enable signal GEN1 are gate drive circuit control signals input from the first gate drive circuit control circuit 36 to the first gate drive circuit 38a. The signal GST2 and the enable signal GEN2 are gate drive circuit control signals input from the first gate drive circuit control circuit 36 to the second gate drive circuit 38b.
[0056]
The clock signal GCK1 is high level in a cycle of two line periods, the start signal GST1 is high level in the first line of the first frame, and the enable signal GEN1 is high level during the first frame period (however, it is low in the last line of the first frame period). Therefore, when the first frame starts, the first gate driving circuit 38a sequentially activates from the first gate line (x1 in FIG. 3). Since the first gate driving circuit 38a is connected to the odd-numbered gate lines of the liquid crystal display panel 81, the odd-numbered lines of the liquid crystal display panel 81 are sequentially activated every two line periods in the first frame period. Since the enable signal GEN1 is at a low level during the second frame period, the odd lines of the liquid crystal display panel 81 are not activated.
[0057]
On the other hand, since the clock signal GCK2 is high level in the period of two lines, the start signal GST2 is high level in the second line of the second frame, and the enable signal GEN2 is high level from the second line of the second frame, the second frame starts. The second gate drive circuit 38b is sequentially activated from the second gate line (x2 in FIG. 3). Since the second gate driving circuit 38b is connected to the even-numbered gate lines of the liquid crystal display panel 81, the even-numbered lines of the liquid crystal display panel 81 are sequentially activated every two line periods in the second frame period. Note that since the enable signal GEN2 is at a low level during the first frame period, the even lines of the liquid crystal display panel 81 are not activated.
[0058]
Therefore, only the odd lines of the first frame of the input progressive scanning video signal can be selected and the time axis can be expanded by a factor of two to display on the odd lines of the liquid crystal display panel 81. In addition, only the even lines of the second frame of the input progressive scanning video signal can be selected, and the time axis can be expanded by a factor of two to display on the even lines of the liquid crystal display panel 81. The above operation is repeated in units of 2 frames.
[0059]
In FIG. 7, a clock signal GCK1, a start signal GST1, and an enable signal GEN1 are gate drive circuit control signals input from the second gate drive circuit control circuit 37 to the first gate drive circuit 38a. The signal GST2 and the enable signal GEN2 are gate drive circuit control signals input from the second gate drive circuit control circuit 37 to the second gate drive circuit 38b.
[0060]
In the first frame period, the clock signal GCK1 is high level in a cycle of two line periods, the start signal GST1 is high level in the first line, and the enable signal GEN1 is high level in the first frame period (however, the last signal in the first frame period) Therefore, when the first frame starts, the first gate drive circuit 38a sequentially activates from the first gate line (x1 in FIG. 3). Further, in the first frame period, the clock signal GCK2 is high level in a cycle of two line periods, the start signal GST2 is high level in the first line, and the enable signal GEN2 is high level during the first frame period (however, in the first frame period) Therefore, when the first frame starts, the second gate driving circuit 38b sequentially activates from the second gate line (x2 in FIG. 3).
[0061]
The first gate drive circuit 38a is connected to the odd-numbered gate lines of the liquid crystal display panel 81, and the second gate drive circuit 38b is connected to the even-numbered gate lines of the liquid crystal display panel 81. In one frame period, the odd-numbered line and the next adjacent even-numbered line of the liquid crystal display panel 81 are simultaneously activated every two-line periods, and thereafter, the odd-numbered and even-numbered lines are simultaneously activated in two-line period cycles. The
[0062]
On the other hand, in the second frame period, the clock signal GCK1 is at a high level in a cycle of two lines, and the start signal GST1 is at a high level in the last line of the first frame. (X1 in FIG. 3) is selected. However, since the enable signal GEN1 is at a low level in the first line period of the second frame, the first gate line is not activated.
[0063]
After that, since the enable signal GEN1 becomes a high level from the second frame second line period, the first gate driving circuit 38 starts the third gate line (x3 in FIG. 3) when the second frame two line period starts. Activate sequentially. In addition, since the clock signal GCK2 is high level in the cycle of two line periods, the start signal GST2 is high level in the second line, and the enable signal GEN2 is high level from the second line period of the second frame, the second gate driving circuit 38b is When the second frame 2 line period starts, the second gate line (x2 in FIG. 3) is sequentially activated.
[0064]
The first gate drive circuit 38a is connected to the odd-numbered gate lines of the liquid crystal display panel 81, and the second gate drive circuit 38b is connected to the even-numbered gate lines of the liquid crystal display panel 81. In the two frame period, the even line and the next adjacent odd line of the liquid crystal display panel 81 are simultaneously activated every two line periods, and thereafter, the even line and the odd line are simultaneously activated in two line period cycles. The
[0065]
Therefore, only the odd-numbered lines of the first frame of the input progressive scanning video signal can be selected, and the time axis can be expanded by a factor of two, so that the odd-numbered lines and the adjacent even-numbered lines of the liquid crystal display panel 81 can be displayed simultaneously. In addition, only the even lines of the second frame of the input progressive scanning video signal can be selected, and the time axis can be expanded by a factor of two, so that the even lines and adjacent odd lines of the liquid crystal display panel 81 can be displayed simultaneously. The above operation is repeated in units of 2 frames.
[0066]
As described above, according to the gate drive circuit control signals of the first and second gate drive circuit control circuits 36 and 37, the odd-numbered lines of the first frame are detected in the two frame periods of the progressive scan video signal inputted. Since one frame consisting of the even lines of the second frame may be displayed, the input progressive scan video signal can be displayed at a speed that is ½ compared to when it is displayed as it is. Therefore, it is not necessary to divide and drive the liquid crystal display panel 81 as in the conventional example, and the occurrence of a luminance difference can be prevented. Further, the number of parallel shift registers of the source driver circuit 323 can be halved and power consumption can be reduced.
[0067]
In the above description, the gate drive circuit 38a is connected to the odd-numbered gate lines of the liquid crystal display panel 81, and the gate drive circuit 38b is connected to the even-numbered gate lines of the liquid crystal display panel 81. ) It is assumed that a gate-on voltage is applied simultaneously to each even-numbered and odd-numbered gate line in a cycle. However, there is a problem when the additional capacitor 171 as shown in FIG. 28 is formed between the gate signal line Xi and the pixel 101. This configuration is referred to as a pre-stage gate configuration.
[0068]
For example, consider the case where the gate-on voltage Vg (+) is applied to the gate signal lines X2 and X3. The TFT 86 becomes active (ON), and the output of the source drive circuit 33 is written to the pixel 101. At this time, assuming that the output of the source driving circuit 33 has a positive polarity, a positive voltage is applied to both terminals of the additional capacitor 171. After 2H, the gate signal voltage Xg becomes the gate-off voltage Vg (-). Therefore, the negative terminal of the additional capacitor 171 is pulled to the negative side, and as a result, the pixel 101 cannot be charged.
[0069]
In order to deal with this problem, in the present invention, the liquid crystal display panel 81 is driven as shown in FIG. In FIG. 8, (a) is the output of the gate drive circuit 38a. However, the output voltage of one gate signal line is not drawn. (b) is the output of the gate drive circuit 38b. Further, (c) is the output of the yj terminal of the source drive circuit 33.
[0070]
As is apparent from FIG. 8, the gate drive circuit shifts the output position of the gate-on voltage every 1H. The gate drive circuits 38a and 38b alternately output a gate-on voltage, and when the other gate drive circuit is outputting a gate-on voltage, the gate drive circuit 38a and 38b outputs a gate-off voltage. Therefore, the gate signal lines Xi are shifted one by one every 1H period by the gate drive circuits 38a and 38b. On the other hand, the source drive circuit 33 changes the value and polarity of the data signal every 2H period. That is, the gate drive circuit 38 operates 1H, and the source drive circuit 33 operates 2H. The source drive circuit 33 is problematic because of its high drive frequency. The gate drive circuit 38 operates at a frequency of (kHz). In the driving method of FIG. 8, the gate-on voltage is not simultaneously applied to the two gate signal lines. That is, the additional capacitor 171 can be sufficiently charged with the pre-stage gate configuration of the liquid crystal display device (described later) shown in FIG. In addition, the operating frequency of the source drive circuit 33 can be reduced.
[0071]
As described above, the gate line scanning method is determined by the gate drive circuit control signal output from the first gate drive circuit control circuit 36 or the second gate drive circuit control circuit 37. In other words, the display method of the liquid crystal display panel 81 is determined by which gate drive circuit control signal output from which gate drive circuit control circuit is selected. The selection of the gate drive circuit control signal is performed by the switch 44 that responds to the switch signal output from the display method selection circuit 35.
[0072]
The progressive scan video signal converted into a digital signal by the A / D converter 40 is input to the display method selection circuit 35. The display method selection circuit 35 calculates a difference for each frame of the input progressive scanning video signal, and determines whether it is a still image or a moving image based on the magnitude of the difference. As a result, the gate drive IC control signal output from the first gate drive circuit control circuit 36 in the case of a still image, and the gate drive circuit control signal output from the second gate drive circuit control circuit 37 in the case of a moving image. Select.
[0073]
More specifically, the display method selection circuit 35 is configured as shown in FIG. If the A / D converter 40 has 8 bits, the A / D converter 40 converts the video signal into 0-255 data. The data is input and held in the first frame memory 871a. The data held in the first frame memory 871a is output with a delay of one frame and input to the second frame memory 871b. Data input to the first frame memory 871a is referred to as input data, and output data is referred to as output data. The output data is delayed by one frame time from the input data.
[0074]
The input data and the output data are subtracted by a subtracter 872. Therefore, the value after the difference is a value of −128 to 127. Next, the data is input to the absolute value circuit 873, and the value “128” is added to become a value of 0 to 255. The reason why the difference between the input data and the output data is taken is to detect the motion of the image between frames. If there is no image movement between frames, the difference value is “0”. The difference value increases as the amount of motion of the image increases.
[0075]
The data output from the absolute value circuit 873 is input to the summation circuit (SUM) 874, and the difference value within one frame period is added. That is, the amount of motion between frames is obtained. It shows that the amount of motion is large, so that the sum total value added is large. The sum difference added for one frame period is sent to the comparator 875 and compared with the reference value of the reference value circuit 876. The reference value is a value that determines that the movement of the image is large when it is equal to or greater than a predetermined value. This value is a value for switching between the first display method and the second display method of the present invention. When larger than the reference value, a signal is transferred from the comparator 874 to the switch 44 so as to select the second display method, and the switch 44 receives the signal and realizes the second display method. On the other hand, when it is smaller than the reference value, a signal is transferred to the switch 44 so as to realize the second display method. That is, when the total value is larger than the reference value, a display method is selected so as to be suitable for a moving image, and when it is small, a display method is selected so as to be suitable for a still image.
[0076]
However, in the case of a video signal at a threshold level that switches between the first display method and the second display method, the first display method and the second display method are switched rapidly, and the display state is as follows. It becomes difficult to see. In order to cope with this problem, it is necessary to not return to the original display state for a certain period after the display method is switched. In other words, it is sufficient to have “hisalosis”. It is easy to have “hisalosis”. The number of times that the comparator 875 outputs a signal for switching the display method is counted, and when the count value is a predetermined value or more, the display method may be switched.
[0077]
In the present embodiment, it is also important that the gate drive circuit 38a is connected to the odd-numbered gate signal line and the gate drive circuit 38b is connected to the even-numbered gate signal line. This is because the first display method and the second display method can be easily realized by this configuration. That is, in the first display method, the gate drive circuit 389 may be animated in the first frame, and the gate drive circuit 38b may be animated in the second frame. In the second display method, each of the gate drive circuits 38a and 38b selects one gate signal line (two in total) in one horizontal scanning period, and sequentially moves the selection signal of the gate signal line. That's fine. If all the gate signal lines are connected to one gate drive circuit, every other gate signal line is not selected in each of the first frame and the second frame in the first display method. It must not be. Thus, selecting every other line complicates the circuit configuration.
[0078]
However, although the gate drive circuit 38a is connected to the odd-numbered gate signal line and the gate drive circuit 38b is connected to the even-numbered gate signal line, there is an exception not limited to this configuration. For example, there is a case where two shift registers 91a and 91b are provided in one gate drive circuit 38. This is a case where the shift register 91a is connected to the odd-numbered gate signal line and the shift register 91b is connected to the even-numbered gate signal line. In this case, apparently there is only one gate drive circuit, but there are two independent shift register circuits. Therefore, there are essentially only two gate drive circuits.
[0079]
In a display that maintains the display state until refreshing, such as an active matrix liquid crystal display (panel), in the case of a still image, vertical interpolation is ensured because interpolation is performed between frames, and in the case of a movie, Due to the interpolation within the frame, no moving image blur occurs, and a good image can be obtained even though the input progressive scan video signal is displayed at a speed half that of when it is displayed as it is. It is done.
[0080]
In the above embodiment, switching by automatic detection has been described, but in addition to this, if the user can forcibly switch the switch 44, it becomes more practical. For example, the switch 44 is exemplified by a push button.
[0081]
Depending on the application, it may be more practical to forcibly switch the switch 44 with a push button or the like without using the display method selection circuit 35. For example, it is possible to determine whether the image displayed on the display 81 is mainly a still image or a moving image. Normally, a progressive signal is input to the display of a workstation, and the displayed image is mostly a still image such as a character or a figure. In this case, the image may be displayed on the display by the first display method (FIG. 1). The first display method can display a high-quality still image. If the display can satisfy the still image, the switch 44 that is sufficiently practical for the use of the workstation may be fixed so that the first display method can be realized. That is, the switch 44 is not necessary. In a television set for home use, an interlace signal is usually input, and most of the displayed images are moving images. Therefore, the switch 44 may be fixed so that the second display method can be realized. The second display method is somewhat unsuitable for displaying still images, but can realize excellent display quality for moving images. In particular, it is presumed that the second display method of the present invention is suitable for displaying a MUSE signal proposed in a high-definition television. As described above, if it is possible to determine whether the display should mainly display a still image or a moving image, the display method selection circuit 35 need not be adopted.
[0082]
Needless to say, the display device of the present invention can also be applied to a simple matrix liquid crystal display panel, an EL panel, a plasma display, a display using PLZT, and a ferroelectric liquid crystal display panel. However, the display device of the present invention employs an active matrix type liquid crystal display panel from the viewpoint of reliability, image quality, cost, and the like.
[0083]
According to the video signal display method described above, video information for one frame is displayed in a two-frame period, so that the input progressive scan video signal is ½ of that when the input progressive scan video signal is displayed as it is. Can be displayed at speed. As a result, even when a wide-band (high-speed data rate) progressive scanning video signal such as a personal computer or workstation is displayed on a display that is not good at high-speed scanning such as a matrix type liquid crystal display, image quality does not deteriorate. In addition, if the first display control means and the second display control means are selectively activated, an optimal display is always obtained according to the nature of the progressive scanning video signal (for example, still image or moving image). It can be performed.
[0084]
Further, when the value representing the correlation between adjacent frames of the progressive scan video signal is equal to or greater than a predetermined value (that is, at the time of a still image), the first display control means is selectively activated, and when it is less than the predetermined value (that is, If the second display control means is selectively activated in the case of a moving image, the vertical resolution can be secured by interpolating between frames in the case of a still image, and within the frame in the case of a moving image. Interpolation is performed to prevent the occurrence of motion blur.
[0085]
The video signal display method as described above is effective when applied to a liquid crystal display panel in which a large number of pixels are arranged in a matrix. A very large number of pixels is, for example, SXGA (width 1280 dots × length 1024 dots). It is not easy to display an image on these display panels. This is because a large number of pixels means that the data transfer rate is very high, and the SXGA transfers a progressive scanning video signal. If an image is to be displayed on SXGA, the number of shift registers in the source drive circuit 33 in parallel becomes very large. This is an operating frequency of 1 to 3 MHz in polysilicon technology or the like. Therefore, it is necessary to extend the time axis so as to adapt to the data transfer rate. This means that the more the time axis is extended, the greater the number of parallel shift registers.
[0086]
Conventionally, it has been sufficient for a home television to support only the NTSC standard (approximately 640 dots wide x 480 dots long). The personal computer should support VGA (horizontal 640 dots × vertical 480 dots). However, in recent years, it has been desired to be compatible with the high-definition (HD) standard, and it is also desired to be compatible with SXGA.
[0087]
The feature of the display device to which the video signal display method of the present invention is applied corresponds to the above-mentioned standard, and therefore, an active matrix type liquid crystal display panel is used, and the display panel has horizontal 1820 dots × vertical 1024 dots. There are also. The number of dots is not limited to 1820 dots, but it is necessary to keep at least 1820 dots ± 100 dots or less. This is because if the distance is too much from 1820 dots, the pixel shape deviates from the vertical 1: 1 square shape and is not suitable for SXGA image display. The horizontal dots require 1024 dots. Even if it is slightly deviated, there may be no problem in practical use, but if it is less than 1024 dots, it becomes impossible to realize complete display of the SXGA screen.
[0088]
FIG. 10 shows an image display state in the display device of the present embodiment. This display device has 1820 × 1024 (16: 9) pixels that can support the HD standard (display area 53a). SXGA (1280 × 1024 (5: 4)) is displayed using a part of it (display area 53b). Further, NTSC and VGA standard images are displayed with (640 × 2) × (480 × 2) (4: 3)) pixels (display region 53c).
[0089]
NTSC and HD are interlaced scanning video signals. VGA and SXGA are progressive scanning video signals. As long as it is compatible with NTSC and HD as a home TV, it is sufficient for the time being. However, there is a strong demand for displaying SXGA. However, in order to apply the liquid crystal display panel to a progressive scan video signal, the number of shift registers in parallel is double that of an interlace scan video signal. Therefore, in order to apply to progressive scanning video signals of SXGA, it is not required in the HD standard. Further, it is necessary to previously form a shift register formed in parallel twice. This is too lossy. This loss refers to the difficulty in manufacturing the TFT array that constitutes the display panel (manufacturing yield, difficulty in design), the demerit that the area where the shift register is formed becomes wider and the effective display area of the panel becomes smaller, the gate signal lines, etc. This is a loss due to the difficulty of the low resistance value of the signal line in order to improve the signal transmission speed to ½ compared to when displaying HD standard signals.
[0090]
In this method, odd-numbered line data is extracted from the progressive scan video signal of the first frame and displayed on the display panel, and even-numbered line data is extracted from the second frame and displayed on the display panel. Form the screen. According to this method, the number of shift registers is a parallel number applicable to the HD standard interlace, and an image based on the progressive scan video signal of the SXGA standard can be displayed. In particular, SXGA or the like is used in a workstation, and most of the images used in the workstation are still images and can be sufficiently applied by this method. Of course, if the second display method is used, it can also be applied to moving image display, and if the switch 44 is operated as in the third display method, it is appropriate according to the video signal (moving image or still image). Image display can be realized.
[0091]
As can be seen from FIG. 10, the SXGA display area 53b is exactly within the HD display area 53a in the vertical direction (it is natural if the display area is vertical 1024 dots). Also, almost no display area (pixel row not displaying an image) is generated in the NTSC (VGA) display area 53c, and most pixels can be used effectively. In addition, the SXGA display area 53b can be “moved” left and right (A and B directions) within the HD display area 53a.
[0092]
The above-mentioned “moving” method is adapted to the multi-window method, and is effective in expanding the application range of the display device of the present invention. In FIG. 3 and the like, the line memory 41 is used for the display line selection circuit 31, but in order to “move”, it is necessary to use the frame memory 51 as shown in FIG. The video signal is converted into digital data by the A / D 40 and input to the frame memory 51. The frame memory control circuit 52 controls the reading of the data and outputs it to the source signal processing circuit 32 through the D / A conversion 42.
[0093]
As shown in FIG. 11, the source drive circuit 33 may be arranged as source drive circuits 33 a and 33 b above and below the liquid crystal display panel 81. If the source drive circuits are arranged vertically, they are applied to the pixels in the column direction, which will be described later, with different signal polarities. There is an effect that the column inversion driving is facilitated.
[0094]
The liquid crystal display panel 81 tends to generate a phenomenon “flicker” in which the screen appears to flicker. Therefore, as shown in FIG. 12, H inversion driving is applied in which signals having different polarities are applied to one row (line) pixel 101 or a plurality of rows. In addition, as shown in FIG. 13, column inversion driving is performed in which signals having different polarities are applied to each pixel 101 or a plurality of columns.
[0095]
In H inversion driving, if FIG. 12 represents the first frame, FIG. 13 represents the signal application state of the second frame. In column inversion driving, if FIG. 14 represents the first frame, FIG. 15 represents the application state of the second frame. Each pixel 101 is applied with a signal having the same polarity in two frame periods.
[0096]
In the above figures, positive polarity is indicated by (+) and negative polarity is indicated by (−). Positive polarity usually indicates a positive direction with respect to the potential of the counter electrode 88, and negative polarity indicates a voltage in the negative direction with respect to the potential of the counter electrode 88.
[0097]
It is easy to realize H inversion driving or the like. As shown in FIG. 16, the video signal is input to the phase division circuit 142 through the amplifier 141. The phase dividing circuit 142 can be easily configured with a transistor Q and two resistors R1 and R2 as shown in FIG. A signal having two polarities, positive polarity (+) and negative polarity (−), is generated by the phase division circuit 142, and the signal is input to the output switching circuit 143. The output switching circuit 143 outputs either a positive polarity signal or a negative polarity signal. When the signal polarity is switched and output every one horizontal scanning (1H) period (2H period in the case of FIG. 10), H inversion driving is performed. When the positive polarity (negative polarity) signal is applied to the source drive circuit 33a and the negative polarity (positive polarity) signal is applied to the source drive circuit 33b at the same time as shown in FIG.
[0098]
It is important to configure the liquid crystal display device so that flicker is not visually recognized. Therefore, the video signal display method of the present invention is as follows. In FIGS. 18 to 22 below, nF on the horizontal axis (n is an integer of 1 or more) indicates each frame. For example, the next frame after 1F is 2F. The vertical axis represents a row (line) of the display panel (display). In the figure, + indicates a positive signal, − indicates a negative signal, and alphabets a, b, and c indicate voltages (amplitudes) applied to the pixel 101. The video signal data included in each frame is different, and a, b, and c are added to the data of each frame.
[0099]
Note that the symbols a, b, and c are merely described for convenience of explanation. For example, in a raster display, a, b, and c will all be the same voltage (amplitude). In the following drawings, + and − are described for convenience of explanation, and + and − may be replaced. The same applies to the following drawings.
[0100]
Hereinafter, the fifth video signal display method will be described with reference to FIG. The fifth video signal display method is a method for displaying an HD standard signal (interlaced scanning video signal (interlaced scanning)) on the display device. It is assumed that the odd-numbered line signal (scan line data) is transferred to the first frame, and the even-numbered line signal is transferred to the next second frame.
[0101]
In FIG. 18, aj (j is an integer of 1 or more) is described in the 1F column. This indicates that the video signal data of the first frame is held in one pixel column of the display panel. Since “+ a1” is described at the top in the 2F column and bj (j is an integer of 2 or more) in the following columns, the video signal data of the first frame is displayed at the top pixel. Is held as it is, indicating that the video signal data of the second frame is held in the other pixels.
[0102]
As is apparent from the above, + a3 and -a3 have the same voltage value held in the pixel 101, and only the polarity of the signal (voltage) is different. Further, if + a3 and + a5, it is video signal data of the same frame, which indicates that the polarity of the signal (voltage) held in the pixel 101 is the same.
[0103]
Note that the actual video signal may have the same or different values for the a1 value of one line and the a5 value of five lines. This is because the same voltage is written in all the pixels 101 if the entire screen is a white raster display. Accordingly, the subscripts are simply different subscripts for convenience of explanation. Further, for example, in FIG. 18, one line of 1F holds + a1 and a positive voltage, but is not limited to this and is only for convenience of explanation. One line may be -a1, two lines may be -a1, three lines may be + a3, and four lines may be + a3. “×” indicates don't care. That is, it is data written in a frame before 1F.
[0104]
Hereinafter, the polarity of the voltage applied and held in the pixel in the video signal display method of the present invention will be described. By considering the polarity of the voltage applied to the pixel as described below, it is possible to significantly reduce flicker recognition. The number of pixels is the same as that described in FIG.
[0105]
FIG. 18 shows a method of displaying an HD standard interlaced scanning video signal on the display panel by the fifth video signal display method. In the odd-numbered frame (F), the same voltage is held in the pixels on the odd-numbered lines and the even-numbered lines following the odd-numbered lines. In the even frame (F), the same voltage is held in the pixels in the even lines and the odd lines that follow. In addition, every two pixels in one row are held in the pixel 101. That is, in the first frame (F), the voltage “++ −− ++ −−...” Is held in the pixels 101 in one column, and “+ −− ++” is stored in the pixels 101 in the next second frame (F). ---... "is held. Further, in the next third frame (F), “−− ++ −− ++...” Is obtained, and in the next fourth frame “− ++ −− ++ −. In the fifth frame, “++ −− ++ −−...” Is the same as that in the first frame.
[0106]
That is, if attention is paid to only one pixel 101, a voltage having a polarity of “++ −− ++ −−” is applied in the frame direction (time axis direction), and there is one cycle in four frame periods. Therefore, since one frame is 1/60 second, it becomes 1/15 seconds in four cycles and flicker occurs. However, voltages having opposite polarities are applied to the upper and lower pixels of the pixel every two frames. For example, if attention is paid to the three-line pixels 101a in the first frame, a voltage of “-++-++” is applied to the pixels in the time axis direction, whereas the two-line pixels 101c are “+-++++”. The voltage is applied as “+”, and the voltage is applied as “− ++ −− ++” to the four-line pixels 101b. Therefore, a voltage having a reverse polarity is applied to a pixel adjacent to the upper or lower side of any pixel where flicker may occur to some extent, so that it is not recognized that flicker has occurred. In addition, since a voltage having a polarity different from “++ −− ++ −−” is periodically applied in the column direction, the flicker is further not recognized.
[0107]
Further, in the fifth video display method, the image display is similar to that obtained by frame interpolation, and is particularly suitable for image display with a large moving image area. This display method is practically sufficient because there are almost no still images on a normal home television. Note that + a1 is applied to pixels on one line of the second frame. This indicates that the voltage + a1 written in one line of the first frame is held as it is. In this way, it is also important to display one line shifted for each frame.
[0108]
FIG. 19 shows a method of displaying a progressive scanning video signal from a workstation or the like on a display device. That is, in the first video signal display method, the polarity of the voltage applied to the pixel is taken into consideration (fourth video signal display method). In the first frame, an odd line signal is extracted from the progressive scan video signal of the first frame and displayed on the odd line. At that time, a positive voltage is applied to the (4n-3) line (where n is an integer of 1 or more), and a negative voltage is applied to the (4n-1) line. In the second frame following the first frame, the even line signal is extracted from the progressive scan video signal of the second frame and displayed on the even line. At that time, a negative voltage is applied to the (4n-2) line (where n is an integer of 1 or more), and a positive voltage is applied to the (4n) line. One screen can be displayed in the above two frame periods.
[0109]
Next, in a third frame following the second frame, an odd line signal is extracted from the progressive scan video signal of the third frame and displayed on the odd line. At that time, each pixel has a polarity opposite to that of the voltage applied to the first frame. In the fourth frame, each pixel has a polarity opposite to that of the voltage applied to the second frame.
[0110]
When the voltage is applied as described above, the polarity of the voltage applied to each pixel becomes the same as that in FIG. Therefore, flicker is not recognized. The display method in FIG. 19 realizes line interpolation. Therefore, it is suitable for still images. Workstations often display graphics, text, or program text, and most of these graphics, text, etc. are still images. Therefore, the display method of the first aspect of the present invention is suitable. The driving frequency (data transfer rate) can also be reduced to ½ that when the progressive scanning video signal is displayed on the liquid crystal display panel 81 as it is. Therefore, even in a panel in which the source drive circuit 33 and the like are formed using polysilicon technology, the number of shift registers in the source drive circuit 33 does not increase.
[0111]
Since HD standard signals are transmitted as interlaced scanning video signals, it is sufficient to display them as interlaced scanning video signals as shown in FIG. As shown in FIG. 19, a progressive scan video signal of a workstation or the like is practically sufficient.
[0112]
The display device of the present invention displays the HD standard interlaced scanning video signal by the display method described with reference to FIG. 18, and displays the progressive scanning video signal and still image by the display method of FIG. In the case of progressive scanning video signals and moving images, the video signal display method of the present invention shown in FIG. 2 is applied as needed.
[0113]
In order to display an NTSC standard image, the method described in FIG. 20 may be used. NTSC standard signals have about 480 effective horizontal scanning lines (number of lines). The display device of the present invention has 1024 effective horizontal scanning lines. Therefore, in order to display NTSC standard signals, 960 out of 1024 are used, which is twice 480. That is, data of one scanning line is displayed on a plurality of lines of the display device. An NTSC standard signal is also an interlaced scanning video signal. As shown in FIG. 18, in order to display the HD standard interlaced scanning video signal, the same display was made on two lines. Since the NTSC standard is 960 lines, which is twice the 480 lines, the data of one scanning line is displayed on four lines as shown in FIG.
[0114]
As shown in FIG. 20, if odd-numbered video signal data is transferred in an odd frame (F) and n is an integer equal to or greater than 1, (8n-7) to (8n-4) lines The same voltage is written in the pixel 101 of the current pixel. If even-numbered video signal data is transferred in the even-numbered frame (F), the same voltage is written to the pixels 101 on the lines (8n-5) to (8n-2) by shifting two lines from the previous frame. In the even frame, the pixels 101 of (8n-7) and (8n-6) hold the data of the odd frame immediately before the even frame. This is because, as shown in FIG. 18, the data “+ a1” of one line of the first frame (1F) is held as it is in the pixels of the first line in the second frame (2F). .
[0115]
In FIG. 20, in order to reduce flicker, the polarity of the voltage written to the pixel 101 is also taken into consideration. That is, in the first frame, a voltage having a polarity of “++++ −−−− ++++...” Is applied in the column direction (1 line to n line), and “++ −−−− ++++ −−.・ ・ ・ "Polarity voltage is applied. Further, a voltage having a polarity of “++ −− ++ −−...” Is applied when viewed in the time axis direction (frame direction = 1F to 9F) around one pixel (for example, pixel 101a). The pixel 101b below the pixel 101a is applied with a voltage having a polarity of “+ −− ++ −−...” So as to be different from the previous pixel 101a. For this reason, flicker is generated when only one pixel is observed, but flicker is canceled as a whole (when one arbitrary pixel and its peripheral pixels are viewed simultaneously) and is not visually recognized.
[0116]
Further, in order to prevent the influence of the occurrence of flicker, the seventh video signal display method shown in FIG. 21 may be performed. In FIG. 20, a voltage of the same polarity (for example, “++++” is applied to the 1st to 4th lines of the first F, and “−−−−” is applied to the 5th to 8th lines of the first F) is applied to the 4th line of one frame. However, in FIG. 21, even if the four lines have the same voltage, the polarity of the voltage is changed every two lines. (For example, 1st to 4th lines of 1F are "++-", and 5th to 8th lines of 1F are also "++-").
[0117]
When displayed as described above, “++ −− ++ −−...” Is displayed in the column direction (1 to n lines) in the first frame, and “−− ++ −− ++ • is displayed in the column direction in the second frame. ... A voltage having the polarity "is applied to the pixel. When viewed in the time axis direction (frame direction = 1F to 9F) around one pixel (for example, the pixel 101a), a voltage having a polarity of “+ − + − + − + −...” Is applied. A voltage having a polarity opposite to that of the pixel 101a is applied to the pixel 101b at the lower position of the pixel 101a, such as “− + − + − + − +...”. Therefore, the occurrence of flicker is suppressed very well.
[0118]
The HD standard signal can be displayed by the display method of FIG. FIG. 21 shows the same data transfer rate as that in the display method of FIG. Therefore, if the display method of FIG. 18 can be realized by the display device of the present invention, it can be easily understood that the display method of FIG. 21 can also be realized.
[0119]
FIG. 22 shows a method for realizing the display of the VGA standard. FIG. 22 is an explanatory diagram of the sixth video signal display method. The display of the VGA standard is displayed using the progressive scanning video signal as it is in the display device of the present invention. The number of effective horizontal scanning lines of the VGA standard is 480. Therefore, the display device of the present invention uses 960 out of 1024, which is twice 480. In order to display the VGA standard, unlike the display methods described so far, it is not necessary to distinguish between odd frames and even frames. Signals corresponding to odd lines in the video signal data of the first frame are displayed on the (4n-3) and (4n-2) lines. The signals corresponding to the even lines are displayed on the (4n-1) and (4n) lines. One line of video signal data is written into the pixel rows of two lines. That is, the progressive scanning video signal is displayed as it is on the two lines of the display device.
[0120]
In order to prevent the occurrence of flicker, consideration is given to the polarity of the signal written to the pixel. The signal polarity is “++ −− ++ −−...” In the column direction in odd frames, and “−− ++ −− ++...” In the column direction in even frames. In the frame direction (time axis direction), “+ − + − + − + −. Therefore, if attention is paid to one pixel, a voltage having the same polarity is applied to the pixel at a period of 1/30 second. Therefore, no flicker occurs.
[0121]
As described above, in the display device of the present invention, HD, NTSC, VGA, and SXGA displays are realized using a liquid crystal display panel having a horizontal number of pixels of 1280 dots and horizontal 1024 dots as shown in FIG. In addition, by using the method described with reference to FIGS. 1, 2, etc., the data transfer rate transferred to the display panel is reduced to ½ of the conventional one, the power consumption is reduced, and the source drive circuit is simplified. Realized. In addition, the generation of flicker is prevented by the method described with reference to FIG.
[0122]
The video signal display method of the present invention can be applied to a display panel of a method in which a voltage is held in a pixel, such as a TN liquid crystal display panel, a ferroelectric liquid crystal display panel, or a display panel using PLET.
[0123]
Among these liquid crystal display panels, a TN liquid crystal display panel that is particularly often used is dependent on the incident angle of light, generates a reverse domain in a pixel, and requires a rubbing process for aligning liquid crystals, and easily causes defects. There are issues such as.
[0124]
The TN liquid crystal display panel depends on the incident angle of light and the display contrast. This occurs because the liquid crystal molecules in the liquid crystal layer 87 are inclined at a constant angle with respect to the normal line of the pixel electrode 151. The display contrast is good if the tilt of the liquid crystal molecules matches the incident angle of light. However, if they do not match, the display contrast is significantly degraded. This problem is serious for a projection display device using a TN liquid crystal display panel as a light valve. This is because it is difficult for the projection display device to make the principal ray of the light incident on the light valve in a certain direction in the entire area of the light valve due to optical design. For example, as shown in FIG. 102, the principal ray of light incident on the TN liquid crystal display panel 691 differs between the upper part and the lower part of the panel.
[0125]
If the tilt of the liquid crystal molecules in the liquid crystal layer 87 coincides with the principal ray c, the display contrast at the lower part of the display area of the light valve 691 becomes good. However, the upper principal ray “a” does not match, and the upper display contrast is remarkably deteriorated. Therefore, the display contrast deteriorates from the bottom to the top of the screen. That is, the image display at the lower part of the screen is good, but the upper part of the screen is in a poor low-quality image display state. This phenomenon significantly reduces image display.
[0126]
Further, as a problem of the TN liquid crystal display panel, there is a light leak (reverse domain region 702) from the pixel peripheral portion of the pixel opening 701 as shown in FIG. This is because the liquid crystal molecules are aligned in the direction opposite to the normal alignment direction. This orientation state is called a reverse chilled domain. This occurs because the rising direction of the liquid crystal molecules is partially reversed by the electric field generated between the pixel electrode and the signal line. In the portion where the rising direction of the liquid crystal molecules is reversed, the light passes through the polarizing plate (analyzer) on the exit surface even though a voltage is applied. That is, light leakage occurs. If the liquid crystal rises normally, no light leaks.
[0127]
As a method for preventing light leakage, there is a method of increasing the width of the black matrix (BM) 703 formed on the counter electrode. That is, the BM 703 is formed so as to hide the reverse domain region 702. This also reduces the pixel closing area, and reducing the display luminance is not an effective method.
[0128]
Further, as described below, in a liquid crystal display panel using TN liquid crystal, light leakage is likely to occur in the peripheral portion of the pixel, so that the black matrix must be thickened. Therefore, the light utilization rate is poor and the display brightness is low. The light irradiated to the black matrix heats the liquid crystal display panel, raises the panel temperature, and shortens the lifetime of the panel.
[0129]
Further, the TN liquid crystal display panel needs to be rubbed by applying an alignment film. The rubbing process increases the number of processes and increases the manufacturing cost. In recent years, the number of pixels of a liquid crystal display panel used in a projection display device has become a large capacity of 300,000 pixels or more, and the pixel size tends to be miniaturized accordingly. Pixel miniaturization results in the formation of a large number of irregularities on signal lines and TFTs, and it is natural that the rubbing process cannot be performed satisfactorily due to the irregularities. Further, miniaturization of the pixel size increases the formation area of TFTs and signal lines occupying one pixel and reduces the pixel aperture ratio. As an example, when 350,000 pixels are formed on a 3-inch diagonal liquid crystal display panel, the pixel aperture ratio is about 30%. When a TFT is formed from amorphous silicon and 1.5 million pixels are formed, there is a predicted value of less than 20%. The reduction of the pixel aperture ratio is not limited to lowering the brightness of the display image, but the liquid crystal display panel is further heated by the light irradiated to the part other than the incident light opening, thereby accelerating the aforementioned performance deterioration.
[0130]
Therefore, in the display device of the present invention, a polymer dispersed liquid crystal is used as the light modulation layer 87. A liquid crystal display panel using a polymer dispersed liquid crystal (hereinafter referred to as a polymer dispersed liquid crystal display panel) is not dependent on an incident angle like a TN liquid crystal display panel, does not generate a reverse tilt domain, and has a rubbing process. It is unnecessary. In addition, since it is not necessary to use a polarizing plate for light modulation, high luminance display can be performed.
[0131]
Hereinafter, a polymer dispersed liquid crystal display panel using the display device of the present invention will be described. Polymer dispersed liquid crystals are roughly classified into two types depending on the dispersion state of the liquid crystal and the polymer (polymer). One is a type in which water droplets of liquid crystal are dispersed in a polymer. Liquid crystals exist in a discontinuous state in the polymer. Hereinafter, such a liquid crystal is called PDLC, and a liquid crystal display panel using the liquid crystal is called a PD liquid crystal display panel. The other is a type that adopts a structure in which a polymer network is stretched around a liquid crystal layer. It looks just like a sponge containing liquid crystal. The liquid crystal exists continuously without being in the form of water droplets. Hereinafter, such a liquid crystal is referred to as PNLC, and a liquid crystal display panel using the liquid crystal is referred to as a PN liquid crystal display panel. In order to display an image on the two types of liquid crystal display panels, light scattering and transmission are controlled.
[0132]
PDLC utilizes the property that the refractive index differs in the direction in which the liquid crystal is aligned. In a state where no voltage is applied, each water droplet liquid crystal is aligned in an irregular direction. In this state, a difference in refractive index occurs between the polymer and the liquid crystal, and the incident light is scattered. When a voltage is applied here, the alignment directions of the liquid crystals are aligned. If the refractive index when the liquid crystal is aligned in a certain direction is matched with the refractive index of the polymer in advance, the incident light is transmitted without being scattered. In contrast, PNLC uses the irregularity of the alignment of liquid crystal molecules. In an irregular orientation state, that is, a state where no voltage is applied, incident light is scattered. On the other hand, light is transmitted when a voltage is applied and the arrangement state is made regular.
[0133]
The above description of the movement of the liquid crystal of PDLC and PNLC is a model way of thinking. In the present invention, the present invention is not limited to one of the PD liquid crystal display panel and the PN liquid crystal display panel, but for the sake of easy explanation, the PD liquid crystal display panel will be mainly described as an example. PDLC and PNCL are collectively referred to as PD liquid crystal.
[0134]
FIG. 23 is an explanatory diagram of the operation of the PD liquid crystal. A TFT (not shown) or the like is connected to the pixel electrode 151, and a voltage is applied to the pixel electrode 151 by turning on / off the TFT to change the liquid crystal alignment direction on the pixel electrode 151 to modulate light. As shown in (a), in the state where no voltage is applied, the liquid crystal molecules in each water droplet-like liquid crystal 181 are aligned in an irregular direction. In this state, a difference in refractive index occurs between the polymer 182 and the water droplet liquid crystal 181, and incident light is scattered. Here, when a voltage is applied to the pixel electrode 151 as shown in (b), the directions of the liquid crystal molecules are aligned. If the refractive index when the liquid crystal molecules are aligned in a certain direction is matched with the refractive index np of the polymer 182 in advance, incident light is emitted from the array substrate 162 without being scattered.
[0135]
The liquid crystal material used for the liquid crystal layer 87 is preferably a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal, and may be a single or a mixture of two or more types of liquid crystalline compounds or substances other than liquid crystalline compounds.
[0136]
Of the liquid crystal materials described above, a cyanobiphenyl-based nematic liquid crystal having a relatively large difference between the extraordinary refractive index ne and the ordinary-light refractive index no, or a fluorine-based or chlorinated nematic liquid crystal that is stable over time is preferable. Among them, chloro nematic liquid crystal is most preferable because it has good scattering characteristics and hardly changes with time.
[0137]
As the polymer matrix material, a transparent polymer is preferable. As the polymer, a photo-curing type resin is used in view of easiness of the manufacturing process and separation from the liquid crystal phase. Specific examples include ultraviolet curable acrylic resins, and those containing acrylic monomers and acrylic oligomers that are polymerized and cured by ultraviolet irradiation are particularly preferred. Among them, a photocurable acrylic resin having a fluorine group is preferable because it can produce a light modulation layer 87 with good scattering characteristics and hardly changes with time.
[0138]
The liquid crystal material is preferably one having an ordinary light refractive index no of 1.49 to 1.54, and more preferably one having an ordinary light refractive index no of 1.50 to 1.53. Further, it is preferable to use one having a refractive index difference Δn of 0.15 or more and 0.30 or less. When no and Δn increase, heat resistance and light resistance deteriorate. If no and Δn are small, heat resistance and light resistance are improved, but scattering characteristics are lowered and display contrast is not sufficient. The scattering characteristic is approximately proportional to the square of Δn.
[0139]
From the above, as a constituent material of the light modulation layer 87, a chloric nematic liquid crystal having an ordinary light refractive index no of 1.50 to 1.53 and Δn of 0.15 to 0.30 is used. It is preferable to employ a photocurable acrylic resin having a fluorine group as a material.
[0140]
Examples of such a polymer-forming monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, neopentyl glycol acrylate, hexanediol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, and trimethylolpropane. Examples include triacrylate and pentaerythritol acrylate.
[0141]
Examples of the oligomer or prepolymer include polyester acrylate, epoxy acrylate, polyurethane acrylate and the like.
[0142]
Further, a polymerization initiator may be used in order to perform the polymerization quickly. Examples of this include 2-hydroxy-2-methyl-1-phenylpropan-1-one ("Darocur 1173" manufactured by Merck & Co.), 1- (4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one ("Darocur 1116" manufactured by Merck), 1-hydroxycyclohexyl phenyl ketone ("Irgacure 184" manufactured by Ciba Geigy), benzylmethyl ketal (Ciba Geigy) "Irgacure 651" manufactured by the company) and the like. In addition, a chain transfer agent, a photosensitizer, a dye, a crosslinking agent, and the like can be appropriately used as optional components.
[0143]
The refractive index np when the resin material is cured and the ordinary light refractive index no of the liquid crystal are made to substantially coincide. When an electric field is applied to the liquid crystal layer, the liquid crystal molecules are aligned in one direction, and the refractive index of the liquid crystal layer becomes no. Therefore, it matches the refractive index np of the resin, and the liquid crystal layer is in a light transmission state. If the difference between the refractive indexes np and no is large, the liquid crystal layer is not completely transparent even when a voltage is applied to the liquid crystal layer, and the display luminance is lowered. The difference in refractive index between the refractive indexes np and no is preferably within 0.1, and more preferably within 0.05.
[0144]
Although the ratio of the liquid crystal material in the PD liquid crystal layer 97 is not specified here, it is generally about 30% to 90% by weight, preferably about 60% to 85% by weight. If it is 30% by weight or less, the amount of liquid crystal droplets is small and the scattering effect is poor. On the other hand, when the content is 90% by weight or more, the tendency for the polymer and the liquid crystal to phase separate into two upper and lower layers becomes stronger, the ratio of the interface becomes smaller, and the scattering property is lowered. The structure of the PD liquid crystal layer varies depending on the liquid crystal fraction. In general, liquid crystal droplets exist as independent droplets (water droplets) at 50% by weight or less, and a continuous layer in which polymer and liquid crystal are intertwined at 50% by weight or more. It becomes.
[0145]
The average particle size of the water droplet-like liquid crystal or the average pore size of the polymer network is preferably 0.5 μm or more and 2.0 μm or less. Among these, 0.7 μm or more and 1.5 μm or less is preferable. When the light modulated by the PD display panel is a short wavelength (for example, B light), the light is small, and when the light is long wavelength (for example, R light), the light is increased. When the average particle diameter of the water droplet-like liquid crystal or the average pore diameter of the polymer network is large, the voltage for setting the transmission state is lowered, but the scattering characteristic is lowered. If it is small, the scattering characteristics are improved, but the voltage for making the transmission state high. In the range of 0.7 to 1.5 μm, the driving voltage is appropriate, the scattering characteristics are high, and the response of the liquid crystal is fast.
[0146]
When a PD liquid crystal display panel is used as a light valve in the projection display device of the present invention, the average particle diameter of the water droplet liquid crystal of the liquid crystal display panel that modulates blue light or the average pore diameter of the polymer network is red light. It is smaller than that of the liquid crystal display panel to be modulated.
[0147]
The PD liquid crystal (polymer-dispersed liquid crystal) referred to in the present invention is a liquid crystal in which a liquid crystal as shown in Japanese Patent Publication No. 61-502128 is dispersed in a resin in the form of water droplets (see FIG. 23). Network), and a liquid crystal filled between the sponges (for example, JP-A-5-173117, JP-A-3-46620, etc.), and JP-A-6-208126, Also included is a resin layered resin as disclosed in JP-A-6-202085. In addition, the liquid crystal is encapsulated in a capsule-shaped storage medium as disclosed in Japanese Patent Application Laid-Open Nos. 5-113558 and 3-52843. Further, liquid crystal or resin 45 containing dichroic or polychromatic dyes (for example, Japanese Patent Application Laid-Open Nos. 59-226322 and 59-178429) are also included.
[0148]
The film thickness of the liquid crystal layer 87 is preferably in the range of 5 to 20 μm, more preferably in the range of 8 to 15 μm. If the film thickness is thin, the scattering characteristics are poor and the contrast cannot be obtained. Conversely, if the film thickness is thick, high voltage driving must be performed, and the gate drive circuit 38 that generates a signal for turning on and off the TFT 86 on the gate signal line and the video on the source signal line. It becomes difficult to design the source drive circuit 33 for applying a signal.
[0149]
As shown in FIG. 24 and the like, black glass beads 233 or black glass fibers, or black resin beads 233 or black resin fibers are used for controlling the film thickness of the liquid crystal layer 87. In particular, black glass beads or black glass fibers are preferable because they have very high light absorption and are hard, so that the number of particles to be dispersed in the liquid crystal layer is small.
[0150]
In the above description, the beads and fibers are black, but the present invention is not limited to this when the liquid crystal display panel is used as a light valve of a projection display device. The projection display device modulates light of three colors of R, G, and B by three display panels. The beads 233 used for the display panel that modulates the R light may absorb the R light. That is, the beads 233 containing a dye having a complementary color relationship with the color of light to be modulated may be used.
[0151]
The liquid crystal layer 87 scatters (displays black) incident light in a state where no voltage is applied. If transparent beads are used, even if the display screen is black, light leakage occurs from the location of the beads and the display contrast is lowered. If black glass beads or black glass fibers are used, light leakage does not occur and good display contrast can be realized.
[0152]
In addition, it is effective to form the insulating film 232 over the pixel electrode 151 and the counter electrode 88. Examples of the insulating film 232 include an alignment film such as polyimide used for a TN liquid crystal display panel, an organic material such as polyvinyl alcohol (PVA), and an inorganic material such as SiO 2. An organic material such as polyimide is preferable from the viewpoint of adhesion and the like.
The PD liquid crystal 87 has a relatively low specific resistance. For this reason, the charge applied to the pixel electrode 151 may not be completely retained for one field (1/30 or 1/60 seconds). If the liquid crystal layer 87 cannot be held, the liquid crystal layer 87 is not completely transparent, and the display brightness is lowered. A thin film made of an organic material such as polyimide has a very high specific resistance. Therefore, the charge retention can be improved by forming a thin film made of an organic material on the electrode. Therefore, high brightness display and high contrast display can be realized.
[0153]
The insulating film 232 also has an effect of preventing the liquid crystal layer 87 from peeling off from the electrodes 88 and 151. This is because nearly half of the material constituting the liquid crystal layer 87 is an organic substance made of resin. Therefore, the insulating film 232 serves as an adhesive layer, and peeling between the substrates 162 and 161 and the liquid crystal layer 87 is difficult to occur.
[0154]
Further, when the insulating film 232 made of an organic material is formed, there is an effect that the pore diameter of the polymer network of the liquid crystal layer 87 or the particle diameter of the water droplet liquid crystal becomes substantially uniform. It is considered that even if an organic residue remains on the counter electrode 88, it is covered with the insulating film 232. The effect of PVA is better than that of polyimide. This is presumably because PVA has higher wettability than polyimide. However, according to the results of reliability tests (light resistance, heat resistance, etc.) conducted by producing various insulating films 232 on the panel, the polyimide used for the alignment film of TN liquid crystal is good with little change over time. is there. Therefore, it is preferable to use polyimide as the insulating film 232 in the display panel of the present invention.
[0155]
Note that when the insulating film 232 is formed using an organic material, the film thickness is preferably in the range of 0.02 μm to 0.1 μm, and more preferably 0.03 μm to 0.08 μm.
[0156]
The PD liquid crystal display panel can realize high luminance display. However, PD liquid crystal display panels also have problems. Hereinafter, the problem and the measures adopted for the display panel (display device) of the present invention
(Configuration) will be explained in turn. When an image is displayed on the PD liquid crystal display panel, light leakage from the peripheral portion of the pixel is a cause of deterioration in display contrast. This occurs because liquid crystal molecules are aligned with the lines of electric force generated between the signal lines and the pixel electrodes. Particularly, as shown in FIG. 104, it becomes prominent when a white window is displayed. This is because the black display areas at the top and bottom of the white display portion are displayed in gray (this phenomenon is hereinafter referred to as black floating). The luminance distribution is as shown in FIG. The black and white lines do not occur in the bb ′ line portion, and in principle, the brightness B1 is constant from the upper part of the screen to the lower part of the screen. However, in the aa ′ line portion, the luminance B1 portion is B2. When a natural image is displayed on the PD liquid crystal display panel, white lines are displayed above and below the white display portion (hereinafter, this phenomenon is referred to as tailing). This phenomenon greatly reduces the image display quality.
[0157]
In order to prevent the above black floating, a black matrix (BM) may be formed in the same manner as in the TN liquid crystal display panel. However, it is not preferable to form BM on the counter electrode 88. When manufacturing a PD liquid crystal display panel, a mixture of an uncured ultraviolet curable resin and liquid crystal (mixed solution) is injected between the counter electrode 88 and the pixel electrode 151, and the resin is cured by irradiating with ultraviolet rays. This is because the resin component and the liquid crystal component are phase-separated. Ultraviolet rays are irradiated from the counter substrate side. When the BM is formed on the counter electrode 88, the resin component under the BM is not cured and the liquid crystal and the resin component are not phase separated. Therefore, the display panel is poor in stability, increases with time, and is substantially difficult to use as a light valve.
[0158]
When the BM is formed on the counter electrode 88, the bonding accuracy between the counter substrate 161 and the array substrate 162 is also important. When the bonding is shifted, light leaks from the end of the BM. In general, the BM width is formed thick in consideration of the bonding accuracy. In general, the bonding accuracy is 5 μm to 10 μm. If the BM is made thicker, the pixel aperture ratio decreases. Accordingly, the display brightness is lowered.
[0159]
Therefore, in the display device of the present invention, the light shielding film 155 functioning as a BM or a similar structure is formed mainly on the pixel electrode 151 side or the like. Usually, no BM is formed on the counter electrode 88 side. Therefore, if ultraviolet rays are irradiated from the counter electrode 88 side at the time of manufacture, an uncured resin component does not occur and a change with time does not occur. If the BM 156 is formed on the pixel electrode 151 side, it is not necessary to consider the bonding accuracy between the counter substrate 161 and the array substrate 162.
[0160]
As an example, the light shielding film 155 (155a to 155e) is formed as shown in FIG. Further, a black matrix (BM) 156 (156a to 156d) is formed. FIG. 25 is a plan view of the array substrate 162 when the counter substrate 161 of the display panel is removed. Each drawing shown below is drawn as a model diagram for easy understanding, and portions unnecessary for description are omitted. 26 is a cross-sectional view taken along line AA ′ in FIG. 25, and FIG. 27 is a cross-sectional view taken along line BB ′ in FIG.
[0161]
FIG. 28 shows an equivalent circuit diagram of the display device. S1 to Sn are source signal lines 154, and G1 to Gm are gate signal lines 153 (153a and 153b). TFTs 86 (86a to 86d) as switching elements are formed at the intersections of the source signal lines 154 (154a and 154b) and the gate signal line 153. One terminal of the TFT 86 is connected to the gate signal line 153 and the other. One terminal is connected to the source signal line 154 and the remaining one terminal is connected to the pixel electrode 151 which is a display pixel. Further, since the necessary charge cannot be stored between one field only by the charge of the liquid crystal layer 87 at the terminal, an additional capacitor 171 is formed between the pixel electrode 151 and the gate signal line 153. Note that a region surrounded by a dotted line in FIG.
[0162]
The material for forming the light shielding film 155 (155a to 155e) is exemplified by chromium (Cr), and its film thickness needs to be 500 angstroms or more in consideration of the light shielding effect. The width of the light shielding film 155 must be determined in consideration of the voltage applied to the signal line 154 and the thickness of the liquid crystal layer 87. When the distance between the counter substrate 88 and the signal line is short, the number of lines of electric force generated between the signal line 154 and the pixel electrode 151 is relatively small. Further, even if the distance between the pixel electrode 151 and the signal line 154 is wide, the number of lines of electric force is relatively small. If the signal amplitude applied to the source signal line 154 is small, the width of the light shielding film 155 can be narrowed.
[0163]
The light shielding film 155 is not limited to a metal thin film. The light shielding film 155 may be replaced with a light absorbing film. The light absorbing material for forming the light absorbing film may be any material that has high electrical insulation and does not adversely affect the liquid crystal layer 87. For example, a black pigment or pigment dispersed in a resin may be used, or gelatin or casein may be dyed with a black acidic dye like a color filter. As an example of the black dye, a single black fluoran dye can be used for coloring, and a color scheme black obtained by mixing a green dye and a red dye can also be used.
[0164]
All of the above materials are black materials, but the display device of the present invention uses three display devices as the projection display device. Each display device is responsible for modulating one of the three colors R, G and B. R light may be absorbed as a light absorbing film of a display device that modulates R light. That is, for example, a light absorbing material for a color filter may be used so as to obtain a desired light absorption characteristic so that a specific wavelength can be absorbed. Basically, similarly to the black absorbing material described above, a natural resin can be dyed with a dye, or a material in which a dye is dispersed in a synthetic resin can be used. The selection range of the pigment is wider than the black pigment, and may be one suitable from azo dye, anthraquinone dye, phthalocyanine dye, triphenylmethane dye, or a combination of two or more of them.
[0165]
Many black pigments have an adverse effect on the liquid crystal layer 87. Therefore, use is not preferable. Therefore, it is preferable to employ a dye capable of absorbing a specific wavelength as described above as the dye contained in the light-absorbing thin film.
[0166]
The projection display device using three display devices for R light, B light and G light as ride valves can be easily adopted. That is, a light-absorbing film may contain a dye having a complementary color relationship with the color of light to be modulated. The complementary color relationship is, for example, yellow for B light. The light absorbing film colored yellow absorbs B light. Therefore. A display device that modulates B light may be formed with a yellow light absorption film.
[0167]
There are two major effects of forming the light absorption film. These effects will be described with reference to FIG. The first effect is an improvement in display contrast. Incident light A is scattered by the water droplet-like liquid crystal 181 and enters the pixel electrode 151. If the light absorption film 155 is formed, the light is absorbed. If there is no light absorbing film 155, the light is incident on and emitted from the array substrate 162 as indicated by the dotted line, so that black floating occurs and the display contrast decreases.
[0168]
A second effect is prevention of light sneaking into adjacent pixels. Incident light B is reflected by the water droplet-like liquid crystal 181, repeatedly reflected between the counter electrode 88 and the pixel electrode 151, and enters an adjacent pixel (indicated by a dotted line). If the light absorption film 155 is formed, it is absorbed by the light absorption film 155 and light does not enter the adjacent pixels. Accordingly, the blur of the pixel is reduced. A structure in which the light absorption film is formed in this way is called a light absorption film structure.
[0169]
Here, since it will be necessary in the following description, P-polarized light, S-polarized light, and the like are defined using FIGS. 30 and 31. P-polarized light refers to light 317 that vibrates on a plane including the normal line 312 of the light source element such as the dichroic mirror 314 and the traveling direction of the incident light beam 311. The “plane including the traveling direction of the light beam” is referred to as a P-polarization plane 318, and an axis on the surface and perpendicular to the traveling direction of the light beam is referred to as a P-polarization axis 315. S-polarized light refers to light that vibrates in a direction perpendicular to the vibration direction 313 of the P-polarized light. A surface on which the S-polarized light vibrates is called an S-polarized surface, and is perpendicular to the traveling direction of the light beam on the surface. The axis is called the S polarization axis. Therefore, the P polarization axis and the S polarization axis are orthogonal.
[0170]
Even in a polymer-dispersed liquid crystal, the polarization dependency occurs due to the alignment of the liquid crystal. The reason why this polarization dependency occurs will be described with reference to FIGS. 32 and 33. FIG. The liquid crystal molecules 281 have different refractive indices in the major axis direction and minor axis direction. In general, a liquid crystal molecule having a positive refractive index is referred to as an extraordinary refractive index ne and a refractive index in the minor axis direction is referred to as an ordinary refractive index no. The polymer-dispersed liquid crystal uses a polymer 182 material whose refractive index is almost equal to the ordinary light refractive index no. The refractive index of the polymer 182 is np. As shown in FIG. 33, when an electric field is generated in the aa ′ direction, the liquid crystal molecules 281 are aligned along the electric field. Then, the refractive index distribution in the aa ′ direction is in a state where the refractive index np (np = no) of the polymer and the extraordinary refractive index ne of the liquid crystal molecules are mixed, and np ≠ ne. Therefore, the polarized light in the aa ′ direction is scattered. On the other hand, in the bb ′ direction, the ordinary refractive indexes no and np are mixed, but since no = np, the polarized light in the bb ′ direction is transmitted without being scattered. From the above, a lateral electric field in the aa ′ direction is generated. When the liquid crystal molecules 281 are aligned by the lateral electric field, polarized light in the bb ′ direction is transmitted and light in the aa ′ direction is scattered. That is, polarization dependency occurs.
[0171]
As will be described later, when a signal having the same polarity is applied to pixels in the line direction (aa ′ direction) as shown in FIG. 12, the horizontal electric field between adjacent pixels is increased in the vertical direction (bb ′ direction, ie, column direction). ). Accordingly, since the liquid crystal molecules are aligned in the bb ′ direction, the polarized light in the aa ′ direction is easily transmitted (light leakage). Therefore, very good contrast cannot be realized unless the lateral electric field is suppressed. Therefore, in implementing the display method of the present invention, various measures have been taken for the panel structure. In this sense, the display method of the present invention and the structure of the display panel are indispensable.
[0172]
As shown in FIG. 34, when there is a potential difference between the pixel electrode 151 and the source signal line 154, an electric force line 263 (lateral electric field) is generated, and the liquid crystal molecules 281 are aligned along the electric field. Since the liquid crystal molecules 281 are aligned in one direction, light leakage occurs in the periphery of the pixel electrode 151, and polarization dependency occurs between the pixel electrode 151 and the signal line 154.
[0173]
In FIG. 35, for ease of explanation, it is assumed that polarized light in the aa ′ direction in FIG. 34 is incident. For ease of explanation, the potential of the counter electrode is set to 0 V (represented as G in the drawing), and the positive potential with respect to the potential of the counter electrode is defined as a positive voltage (represented as + in the diagram). A negative potential with respect to the potential of the electrode is assumed to be −voltage (denoted as − in the drawing).
[0174]
In FIG. 35, (a), (b), and (c) show the state of generation of electric lines of force in the liquid crystal layer 87, and (d), (e), and (f) show the position x of the array substrate 162 on the horizontal axis. And the vertical axis represents the transmittance T. That is, the distribution of transmitted light is conceptually shown. (a), (b), and (c) show a state in which a positive voltage is applied to the pixel electrode 151 and a negative voltage is applied to the source signal line. Electric field lines are generated between the counter electrode 88 and the pixel electrode 151 (electric field line 263a) and between the pixel electrode 151 and the source signal line 154 (electric field line 263b). In this manner, the electric field generated between the pixel electrode 151 and the signal line is called a transverse electric field. The liquid crystal molecules 281 are aligned along the electric lines of force 263 when the intensity of electric lines of force (electric field intensity) is equal to or greater than a predetermined value (rising voltage of the liquid crystal). When the direction of the electric lines of force 263 is perpendicular to the counter electrode 88, if the liquid crystal molecules 281 are aligned along the electric lines of force, the apparent refractive index of the liquid crystal layer becomes the ordinary refractive index no. Since no and the refractive index np of the polymer 182 have a relationship of no≈np, the liquid crystal layer 87 is in a transparent state. On the other hand, when the direction of the electric force line 263 is parallel to the counter electrode 88, if the liquid crystal molecules are aligned along the electric force line 263, the apparent refractive index nx of the liquid crystal layer is (no + ne) / 2, and nx Since ≠ np, the liquid crystal layer 87 is in a scattering state.
[0175]
The liquid crystal layer between the pixel electrode 151 and the signal line 154 is in a scattering state by the lateral electric field 263. Since the direction of the electric lines of force 263 around the pixel electrode 151 is inclined with respect to the counter electrode 88, the light transmission state occurs. Therefore, the distribution of the transmitted light T is shown by (d).
[0176]
In FIG. 35, (b) shows the case where the potential of the pixel electrode 151 is the G potential. In this case, only the electric force lines 263b between the signal line 154 and the pixel electrode 151 are generated. Such a potential state occurs in the pixels in the display area above and below the white display portion in (a). Since the upper and lower display area pixels are black, there is no potential difference between the counter electrode 88 and the pixel electrode 151. However, since a signal applied to the pixel of the white display portion is applied to the source signal line 154, an electric force line 263b is generated by a lateral electric field. Accordingly, the liquid crystal layer 87 around the pixel is in a semi-transmissive state, and light leakage occurs. In the display panel of the present invention, as shown in (c), since the light shielding film 155 is formed in the periphery of the pixel electrode, light leakage does not occur and good black display can be realized.
[0177]
According to experiments, light leakage around the pixel electrode is large, but light leakage between the pixel electrode 151 and the signal line 154 is relatively small. Therefore, in many cases, the type of the light-shielding film 155 alone is practically sufficient without disposing a polarizing plate on the PD liquid crystal display panel. A higher brightness display is often desired.
[0178]
In the case of using a polarizing plate, the polarizing axis of the polarizing plate is matched with the direction in which the transverse electric field is generated. For example, when a lateral electric field is generated between the source signal line 154 and the pixel electrode 151, the polarizing plate 331 and the display panel 81 are arranged as shown in FIG. 36 (the polarization axis 332 is the direction in which the gate signal line is formed). . 36 and FIG. 37, the solid line arrow indicates the horizontal electric field generation direction of the display panel, and the dotted line arrow indicates the polarization axis (polarization direction) of the polarizing plate. The polarizing plate may be arranged on both the light incident side and the light emitting side of the PD liquid crystal display panel as shown in FIG. 36 (a), and one of them as shown in FIGS. 36 (b) and 36 (c). It may be only. Although it is needless to say that the contrast display is good in (a), the display brightness is reduced by the transmittance of the polarizing plate 331. Which method of FIG. 36 is used may be determined in consideration of the light utilization rate, cost, and display contrast. Note that a configuration using such a polarizing plate 331 is referred to as a polarizing plate structure.
[0179]
36 and 37, the polarizing plate 331 is disposed. However, the technical idea of the present invention is to allow linearly polarized light to enter the liquid crystal display panel 81 in consideration of the generation direction of the transverse electric field. One realization means is to use a polarizing plate 331. As another method, there is a method using a polarization beam splitter 361 as shown in FIG. The incident light 363 is separated into P-polarized light and S-polarized light by the light separation surface 362 of the polarization beam splitter 361. One of the P-polarized light and the S-polarized light is made incident on the liquid crystal display panel 81.
[0180]
In FIG. 34 and the like, the positive polarity is represented as + and the negative polarity is represented as − with respect to the counter electrode 88 without considering the magnitude of the writing voltage in the pixel electrode 151. In reality, the voltage applied to each pixel cannot be the same unless it is a raster display. However, since signals of almost the same level are applied between adjacent pixel electrodes 151, it is considered that a signal (voltage) of the same level is written to a pixel in the vicinity of an arbitrary pixel. In many cases, there is no problem. In other words, if the polarities of the voltages applied to the pixels match between the adjacent pixel electrodes 151, no horizontal electric field is generated between the pixel electrodes 151. Conversely, a horizontal electric field is generated if the polarities of the pixel electrodes 151 are the same even if the absolute values of the voltages are the same.
[0181]
If no electric field is generated from the source signal line 154 and the liquid crystal molecules are aligned by a horizontal electric field generated only between adjacent pixel electrodes and light leakage occurs, the horizontal electric field in the case of H inversion driving in FIG. The direction of occurrence is the bb ′ direction. Therefore, the polarized light in the aa ′ direction is easily transmitted. Therefore, if the polarizing plate 331 is arranged as shown in FIG. 37, light leakage can be prevented. In the case of the column inversion driving of FIG. 11, the horizontal electric field generation direction is opposite to that in FIG. Therefore, a polarizing plate 331 may be disposed as shown in FIG.
[0182]
The display direction of the present invention is H inversion driving in which the same polarity is applied in the line direction. Therefore, when using a polarizing plate, it arrange | positions like FIG. This matter is an important matter for the present invention. This is because, in combination with the polarizing plate structure of FIG. 37, light leakage around the pixel electrode 151 due to a lateral electric field can be completely prevented, and a very good display contrast can be realized. As described above, the technical idea of considering the polarity of the voltage applied to the pixel electrode 151 and the polarization axis 332 of the polarizing plate 331 is an important matter in the polarizing plate structure described above.
[0183]
As described above, a lateral electric field is generated in the PD liquid crystal display panel. For this reason, light leaks from the periphery of the pixel electrode 151. Measures against light leakage due to a transverse electric field are important matters for realizing a very good display contrast.
[0184]
One of the countermeasures is a light shielding film structure to which a light shielding film 211 shown in FIG. 25 is added. Although the light shielding film 155 (which may be considered as a light absorption film) is formed on the pixel electrode 151, it may be formed on the counter electrode 88 as shown in FIG. 39 (light shielding film 211). In manufacturing, when the liquid crystal and the resin component are phase-separated, the light-shielding film 211 generates an unpolymerized resin component, which can be solved by the following method.
[0185]
First, after unpolymerized resin and liquid crystal are injected between the pixel electrode 151 and the counter electrode 88, ultraviolet rays are irradiated from the A direction. Since the resin below the light shielding film 211 remains unpolymerized, the remaining unpolymerized resin is cured by irradiating ultraviolet rays from the B direction. The resin on the light shielding film 211 is cured from the B direction, and the resin on the source signal line 154 is cured from the A direction. Therefore, the liquid crystal layer 87 can be completely phase-separated from the liquid crystal and the resin component.
[0186]
In order to expand the allowable range of positioning for bonding the counter substrate 161 and the array substrate 162, as shown in FIG. 40, in addition to the structure of FIG. 39, a light shielding film 155 is formed on the pixel electrode 151. There is. With this configuration, light leakage does not occur from the periphery of the pixel electrode 151 even if the bonding is slightly shifted. That is, the light-shielding film 155 and the light-shielding film 211 may be overlapped by an allowable range when seen from the A direction.
[0187]
If the BM is not formed as in the conventional TN liquid crystal display panel, the resin on the source signal line 154 remains uncured in the PD liquid crystal display panel. This is because BM exists on the counter electrode 88 on the source signal line 154. In the present invention, as shown in FIG. 25 or 39, since the light shielding film is removed on the source signal line 154, uncured resin does not occur. The light shielding films 155 and 211 may be replaced with a light absorption film structure as described above.
[0188]
Further, as shown in FIG. 24, the light shielding film 231 may be formed between the pixel electrode 151 and the signal line 154 and further on the signal line 154. In this case, the light shielding film 231 must be formed of an insulating material. As the insulating material, it is not necessary to explain that the coloration black exemplified in the light absorption film structure or the acrylic resin containing carbon or the like can be used.
[0189]
The light shielding films 155, 231 and 211 are formed around the source signal line 154 or on the signal line, but the invention is not limited to this. Obviously, it should be formed around or on the gate signal line 153. If H inversion driving is performed as shown in FIG. 12, a horizontal electric field is generated between the upper and lower pixels, and light leakage occurs.
[0190]
As a configuration for preventing light leakage due to a lateral electric field, FIG. 41 shows a configuration in which the source signal line 154 or the gate signal line 153 is surrounded by a low dielectric constant material. The signal line 154 is surrounded by a low dielectric film 241. The low dielectric material means a material having a relative dielectric constant lower than that of the liquid crystal layer 87. The relative dielectric constant of the polymer 32 constituting the liquid crystal layer 87 is around 5, and the relative dielectric constant of the liquid crystal is 15-30. Since the liquid crystal layer 24 is a mixture of the polymer 182 and the liquid crystal, the relative dielectric constant thereof is 5 or more and 30 or less.
[0191]
Examples of the material of the low dielectric film 241 include the same material of the polymer 182, an inorganic material such as SiO 2 and SiNx, or a resist material used in a semiconductor process. Since the low dielectric film 241 needs to be relatively thick, it is preferable to use an organic material such as the polymer 182 or a resist. Such a configuration is called a low dielectric film structure. If necessary, a low dielectric film 241 is also formed on the gate signal line 153.
[0192]
The low dielectric film is formed at a location where a lateral electric field is generated. A thicker film is better. Since the PD liquid crystal display panel does not require an alignment treatment such as rubbing, there is no problem even if the low dielectric film 241 causes irregularities on the surface of the array substrate 162 or the like. This is a great advantage of the PD liquid crystal display panel, which is different from the TN liquid crystal display panel.
[0193]
In addition, if a low-dielectric film 241 is mixed with a dye using a light-shielding film 155 or the like, it becomes a light-shielding film. The relative dielectric constant hardly increases even when a pigment or the like is mixed. However, when carbon is used as the dye, the relative permittivity is somewhat higher. In addition, the amount of capacitive coupling between the pixel electrode 151 and the source signal line 154 increases in the low frequency region. However, the amount of capacitive coupling hardly increases in the frequency band normally applied to the source signal line 154.
[0194]
Further, when the display device of the present invention shown in FIG. 41 or the like is used as a light valve in a projection display device, it is not necessary to use carbon as a pigment. This is because in the projection display device, each light valve modulates only one color of red (R), green (G), and blue (B), and functions as a light shielding film if it absorbs the one color. It is. For example, when the modulated light is blue, it is a yellow pigment.
[0195]
The light shielding film used in the light shielding film structure is not limited to an insulator such as resin. For example, an insulating film may be stacked on the source signal line 154, and a light shielding film made of metal may be formed on the insulating film. For example, it is a thin film made of chromium (Cr) and aluminum (Al). If hexavalent chromium is used, the hexavalent chromium is black and also functions as a light absorption film.
[0196]
As described above, the light-shielding film structure of the present invention is a structure in which the periphery of the pixel electrode is shielded, and its configuration (resin or metal thin film) is not a problem. If the light absorption effect shown in FIG. 29 is not required, the light may be reflected and blocked. In a material having a low dielectric constant, it is difficult for electric lines of force to pass through. Therefore, the lateral electric field is weakened and no light leakage occurs.
[0197]
The thicker the low dielectric film 241 is, the greater the effect of preventing a lateral electric field and preventing light leakage. Therefore, the low dielectric film 241 may have a structure that completely fills the space between the counter electrode 88 and the signal line 154 (see FIG. 42). Also, light leakage can be prevented by covering the outer peripheral portion of the pixel electrode 151 larger.
[0198]
In the configuration of FIG. 42, the low dielectric film 262 becomes a column (hereinafter referred to as a low dielectric column), which is a means for maintaining a constant distance between the counter electrode 88 and the pixel electrode 151. That is, it is not necessary to use the beads 233 used to keep the liquid crystal layer 87 film thickness as shown in FIG. This is an important matter. Since the TN liquid crystal display panel requires a rubbing process, if a low dielectric column 262 as shown in FIG. 42 is formed, the rubbing cloth is obstructed by the column 262 during the rubbing process, and the alignment process is not performed. It will be possible. The configuration shown in FIG. 42 is the first configuration that is possible with a PD liquid crystal display panel. As a matter of course, it is desirable to mix the low dielectric column 262 with a dye to form a “light blocking column”.
[0199]
As shown in FIG. 42, the electric lines of force 263b are not generated at all because they are shielded by the low dielectric column. Therefore, light leakage due to the transverse electric field is eliminated. The electric lines of force are generated straight on the pixel electrode 151 and the counter electrode 88 (electric lines of force 263a). The low dielectric column 262 also has a function of defining the film thickness of the liquid crystal layer 87. That is, it plays a role as the bead 233 that defines the liquid crystal film thickness. Therefore, it is not necessary to spread the beads 233. Therefore, there is no light leakage around the bead 233 and the display contrast is good.
[0200]
In addition, there is an advantage that alignment is not required when the counter substrate 161 and the array substrate are bonded together. The low dielectric column 262 is preferably formed on the counter electrode 88. This is because there are no other components on the counter electrode 88 and it is easy to form a low dielectric column. This is because the array substrate 162 has irregularities on which TFTs and the like are formed, and it is difficult to form a low dielectric column. On the other hand, the counter electrode 88 has extremely high smoothness, and it is easy to form a low dielectric column.
[0201]
FIG. 43 shows a configuration in which the BM 261 is formed on the low dielectric column 262. In this case, the BM 261 is formed on the low dielectric pillar 262. With this configuration, light leakage does not occur at all even if the low dielectric column 262 is a transparent material.
[0202]
FIG. 44 shows a modification of FIG. 41. When the insulating film 163 is used to insulate the source electrode 154, the gate electrode 163, and the pixel electrode 151, a low dielectric film 241 is formed in the vicinity of the source electrode 163. .
[0203]
45 is a plan view of a display device according to another embodiment of the present invention, FIG. 46 is a cross-sectional view taken along line CC ′ of FIG. 45, and FIG. 47 is DD ′ of FIG. It is sectional drawing in a line. In the embodiment shown in FIG. 45, an additional capacitor (capacitor) 171 is formed between the pixel electrode 151 and the gate signal line 153. The additional capacitor 171 is formed by forming an insulating film 163 on the gate signal line 153 and overlapping the pixel electrode 151 on the insulating film 163. The gate signal line 153 branches along the source signal line 154. The pixel electrode 151 is preferably formed so as to shield the gate signal line 153 as much as possible.
[0204]
The additional capacitor 171 is formed at the periphery of the gate signal line 153 and the pixel electrode 151 and is formed around the same position as the light shielding film 155 in FIG. Since the gate signal line 153 is usually formed of a metal thin film, the branched gate signal line has a function as the light shielding film 155.
[0205]
The display device of FIG. 25 is a pre-stage gate system. In the pre-stage gate method, the gate signal line 153 has a large width, and the gate signal line 153 and the pixel electrode 151 are overlapped to obtain a predetermined capacitor capacity. However, if the width of the gate signal line 153 is increased, the pixel aperture ratio decreases. In FIG. 45, after the charge can be accumulated between the branched gate signal line 153 and the pixel electrode 151, the gate signal line width can be reduced as compared with the case where there is no branch by the charge. Further, the branched gate signal line portion has the function of the light shielding film 155. Therefore, the aperture ratio of the display device in FIG. 25 can be made equal to the aperture ratio of the conventional front gate type display device.
[0206]
Light leakage from the periphery of the pixel due to a lateral electric field between the source signal line 154 and the pixel electrode 151 can be prevented by the branched gate signal line 153. That is, in FIG. 25, the light shielding film 155 may be replaced with the gate signal line 153.
[0207]
When a certain signal is applied to the source signal line 154 or the gate signal line 153, a line of electric force (lateral electric field) is generated between the pixel electrode 151 and the signal line by the voltage of the signal. A polarization dependency occurs in which the liquid crystal is aligned by a lateral electric field. For this reason, light leakage occurs in the periphery of the pixel electrode 151. In order to prevent this, it is preferable to cover the signal line 154 and the like with a low dielectric film shown in FIG. However, even if the electric lines of force from the signal lines or the like are completely shielded, a horizontal electric field is generated by the electric lines of force generated between the adjacent pixel electrodes 151. In order to prevent this lateral electric field, the configuration in which the low dielectric column 262 of FIG. 42 is formed is effective. A method using a polarizing plate 331 or the like is also effective.
[0208]
In the video display method of the present invention, the voltage polarity applied to the pixel 101 is as shown in FIG. Therefore, the horizontal electric field is generated between adjacent pixel electrodes in the bb ′ direction. When the polarizing plate 331 is used, the polarization axis 332 needs to be in the bb ′ direction as shown in FIG. The electric lines of force from the source signal line 154 are completely shielded by using the low dielectric film 241 and the low dielectric pillar 262, or the light shielding film 155 or 231 prevents light leakage.
[0209]
In the image display method of the present invention and the display device adopting the image display method, a voltage having a predetermined polarity is applied to the pixel electrode 101 as shown in FIG. 12, but it is also preferable to adopt the following driving method. . The thicker the liquid crystal layer 87, the better the scattering characteristics. Accordingly, the display contrast is increased. However, a high voltage is required for transmission through the liquid crystal layer 87. If the method of FIG. 12 is used, a high voltage can be effectively applied to the liquid crystal layer 87.
[0210]
First, the polarity of the potential of the counter electrode 88 should be inverted every horizontal scanning period (H) (1H or 2H) ((a) of FIG. 48). The potential of the counter electrode 88 is applied with a potential of ± V1 + with a period of 4 horizontal scanning periods (4H) with the G1 potential as the center. The reason why it is set to 4H is that a voltage having the same polarity is applied every two lines as shown in FIG. On the other hand, in the pre-stage gate method (method in which a capacitor is formed between the gate signal line 153 and the pixel electrode 151 and the additional capacitor 171 is configured) shown in FIG. Apply. Note that the gate signal line is not considered here in order to facilitate description of applying a voltage for turning on and off the TFT 86. This driving method is called a floating gate method.
[0211]
FIG. 50 is an explanatory diagram of the floating gate method. A rectangular wave 801 having a 4H period is applied to the counter electrode 88 by the driving means 821. On the other hand, a rectangular wave 802 having a 4H cycle is applied to the gate signal line 153 by the driving means 822. The capacitor capacity of the liquid crystal layer 87 is C1, and the capacity of the additional capacitor 171 is C2. In order to facilitate further explanation, there is a relationship of C1 << C2. In the case of TN liquid crystal, the capacitor capacitance C1 of the liquid crystal layer is relatively large. However, in the case of PD liquid crystal, the capacitor capacitance C1 of the liquid crystal layer is often sufficiently smaller than the capacitance C2 of the additional capacitor. This is because the relative permittivity of the PD liquid crystal is low and the liquid crystal layer 87 is as thick as 8 μm or more. The TFT 86 is regarded as a switch, and the voltage waveform applied to the gate signal line is output to the pixel electrode 151 almost without attenuation. This is because there is a relationship C1 << C2. For ease of explanation, V1 = 4V and V2 = 4V. Further, the video signal voltage Vs output from the source drive circuit 33 varies depending on the video signal, but here it is assumed that Vs = ± 6V.
[0212]
50A, V1 + = 4V is applied to the counter electrode 88, and at that time, the gate signal line V2 + = + 4V is applied. (The level of the off voltage is not considered in the explanation). At this time, for example, a voltage of Vs = 6 V (this is a video signal from the source drive circuit 33) is applied to the pixel electrode 151 by the TFT 86. Then, a voltage of + 4V − (− 6V) = 10V is applied to the liquid crystal layer 87. This is the period (a) in FIG. Next, in the period of FIG. 80B, V1 + = 4V is applied to the counter electrode 88 as shown in FIG. 50B, and at that time, the gate signal line V2-=-4V is applied. Since the counter electrode 88 and the gate signal line potential V2 are electrodes common to all the pixels, the voltage applied in FIG. 50A is changed by changing the voltage V2 to V2- and V1 to V1-. −6V changes to −6V + V2 − = − 6V + (− 4V) = − 10V. However, the voltage applied to the liquid crystal layer 87 does not change to 10V. In FIG. 50B, a voltage of +6 V is applied to the pixel electrode 151. Accordingly, a voltage of −4 V − (− 6 V) = − 10 V, that is, 10 V is applied to the liquid crystal layer 87.
[0213]
As described above, the voltage Vs and the voltage V2 or V1 from the source drive circuit are constantly applied to the liquid crystal layer. Thus, the method of changing the voltage of the counter electrode 88 in a 4H cycle is a feature of the present invention. In particular, the PD liquid crystal display panel is convenient because the capacitor capacitance C1 of the liquid crystal layer 88 is small. This is because if C1 is larger than a certain value compared to C2, it is difficult to apply a voltage to the pixel electrode 151 even if V2 is changed.
[0214]
The above description is a description of the driving system for the structure of the previous gate system. In addition, it can be applied to the common electrode system shown in FIG. In the common electrode system, an additional capacitor 171a is formed by a common electrode 831 and a pixel electrode 151 formed in different layers. In the common electrode method, if the common electrode 831 is replaced with the gate signal line 153 in FIG. 50, the above-described floating gate method can be realized. That is, it can be considered that the driving means 822 is connected to the common electrode 831. Since other matters have been described with reference to FIGS. 48 and 50, description thereof will be omitted.
[0215]
In the common electrode system, it is necessary to form the common electrode 831 in a separate layer, and there is a disadvantage that the number of masks increases in the array formation process. However, it is not necessary to use the gate signal line 153 as one electrode of the additional capacitor 171. This increases the degree of freedom in designing the additional capacitor capacity. In addition, there is an advantage that the pixel aperture ratio is generally increased. In particular, the circuit configuration of the drive circuit 33 is simple. Therefore, it is preferably employed when the drive circuit 33 and the like are formed by polysilicon (particularly low temperature polysilicon) technology as in the display device of the present invention.
[0216]
When the display device of the present invention is used as a light valve of a projection display device, the following problems may occur. It is a ghost or display contrast reduction due to reflection on the metal thin film on the back surface of the liquid crystal display panel.
[0217]
As shown in FIG. 52, the incident light 451 is scattered by the water droplet liquid crystal 181 of the liquid crystal layer 87. The scattered light 452 becomes transmitted light 454a, but part of it becomes reflected light 453a. The reflected light 453a is reflected by a metal thin film such as the source signal line 154, becomes a thin film 453a, and further becomes transmitted light 454b. The transmitted light 454b becomes a ghost when projected on the screen. In addition, the image is irregularly reflected by a projection lens or the like, and the display contrast is lowered.
[0218]
The PD liquid crystal display panel performs light modulation by scattering incident light by the liquid crystal 87. Therefore, much light is incident on the interface 455 at a critical angle or more. Light above the critical angle is totally reflected. Therefore, the ratio of light reflected at the interface and incident on the metal thin film surface such as the source signal line 154 or the gate signal line 153 is larger than that of the TN liquid crystal display panel or the like. Therefore, it is important to eliminate the cause of the ghost. If the pixel aperture ratio is 50%, it can be considered that most of the portions other than the aperture are formed of a metal thin film.
[0219]
As a first countermeasure against the ghost, in the liquid crystal display device of the present invention, an antireflection film is formed at the interface 455 between the panel and air. The antireflection film is formed by stacking three or two thin films. In the case of three layers, it is used to prevent reflection in a wide wavelength band of visible light, and this is called multi-coat. In the case of two layers, it is used to prevent reflection in a specific visible light wavelength band, and this is called a V coat.
[0220]
In the case of multi-coating, aluminum oxide (Al 2 O 3) is formed by laminating optical film thickness nd = λ / 4, zirconium (ZrO 2) nd = λ / 2, and magnesium fluoride (MgF 2) nd = λ / 4. To do. Usually, in the case of G light, a thin film is formed with a value of 520 nm or a value in the vicinity thereof. In the case of V coat, silicon monoxide (SiO) has an optical film thickness nd = λ / 4, magnesium fluoride (MgSO 4) nd = λ / 4, or yttrium oxide (Y 2 O 3) and magnesium fluoride (MgSO 2) = Λ / 4 layered. Since SiO has an absorption band on the blue side, it is better to use Y2O3 when modulating blue light. In view of the stability of the substance, Y2O3 is preferable because it is more stable. Here, λ is the peak wavelength of the light to be modulated, that is, the center wavelength. n is the refractive index of the thin film, and d is the physical film thickness.
[0221]
However, a multi-coat or V-coat antireflection film is not sufficient. This is because light incident on the interface 455 at a critical angle or more cannot be prevented from being reflected by the interface 455. Therefore, it is preferable to employ the configuration shown in FIG. 53 or 54 as a second countermeasure.
[0222]
FIG. 53 shows a configuration in which irregularities are formed in a metal thin film (source signal line 154 and the like), and such a configuration is called a convex structure. FIG. 55 is a cross-sectional view taken along line EE ′ of FIG. First, a convex portion 411 is formed at a position where a metal thin film is formed on the array substrate 162. Examples of the material for forming the convex portions 411 include inorganic materials such as SiO 2 and SiN x. A metal thin film such as a source signal line 154 is formed in alignment with the convex portion 411. In addition, the convex part 411 may be formed periodically and may have a diffraction effect. The light 453 a reflected at the interface 455 and returned from the source signal line 154 has its traveling direction changed by the convex portion 411. Therefore, the transmitted light 453b is not generated and no ghost or the like occurs.
[0223]
54, a light shielding film 431 is formed on the array substrate 162, and a source signal line 154 and the like are formed on the light shielding film 431. Such a configuration is referred to as a lower layer light shielding film structure. Needless to say, the light shielding film 431 preferably has a light absorption film structure.
[0224]
Examples of the constituent material of the light shielding film 431 include a material for forming the light shielding film 155 in FIG. 25 or the light shielding film 231 in FIG. 24 in addition to a metal material such as hexavalent chromium. An insulating film 432 is formed on the light shielding film 431, and the peripheral portions of the source signal line 154 and the pixel electrode 151 are overlaid on the insulating film 432. The light shielding film 431 in the lower layer portion of the pixel electrode 151 corresponds to the light shielding film 155 in FIG.
[0225]
In the configuration of FIG. 54, since the light shielding film 431 is also formed in the lower layer between the pixel electrode 151 and the signal line 154, no light leakage occurs between the pixel electrode 151 and the signal line 154. Further, since the reflected light 453a can be absorbed by the light-shielding film 431, no ghost or the like is generated.
[0226]
Also in the TFT 86, a countermeasure against the reflected light 453a is important. When light enters the semiconductor layer of the TFT 86, a photoconductor phenomenon (a phenomenon in which the off characteristics of the TFT deteriorate) occurs. When the photoconductor phenomenon occurs, the electric field applied to the pixel electrode 151 cannot be held for one frame period, the brightness of white display is lowered and display contrast is deteriorated.
[0227]
In order to prevent the occurrence of the photoconductor phenomenon due to the reflected light 453a, in the display panel of the present invention, a light shielding film 431 is formed below the semiconductor layer 445 of the TFT 86 as shown in FIG. Therefore, the reflected light 453a can prevent the occurrence of the photoconductor phenomenon absorbed by the light shielding film 431. The TTF 86 includes a gate electrode 444, a drain electrode 442, a source electrode 443, a SiNx layer 441, and a semiconductor layer 445.
[0228]
The TN liquid crystal display panel is twisted 90 degrees so that liquid crystal molecules are aligned, and light is modulated by rotating the polarization direction along the pre-twist direction. Therefore, no light is scattered. Therefore, the amount of light reflected by the interface 455 is small. However, the PD liquid crystal display panel modulates by scattering incident light as described with reference to FIG. Therefore, the light reflected by the interface 455 is increased. Therefore, the significance of adopting the configuration shown in FIGS. 53 to 56 is great. This can be considered as a configuration unique to the polymer-dispersed liquid crystal display panel.
[0229]
For light of a specific wavelength, there are an average particle size of water droplet-like liquid crystal and an average pore size of a polymer network that optimize the scattering characteristics of PD liquid crystal. In general, the longer the wavelength of light (red light), the larger the average particle size of the water droplet liquid crystal. Conversely, the shorter the wavelength of light (blue light), the better the scattering characteristics as the average particle diameter of the water droplet liquid crystal is reduced. Therefore, it is preferable that the average particle diameter or the like of the display panel that modulates red light is larger than the average particle diameter or the like of the display panel that modulates blue light. The average particle diameter can be changed by changing the intensity of the ultraviolet rays when the mixture solution is injected and then irradiated with ultraviolet rays. When a strong ultraviolet ray is irradiated for a short time, the average particle diameter of the water droplet-like liquid crystal becomes small. On the other hand, when weak ultraviolet rays are irradiated for a long time, the average particle diameter of the water droplet liquid crystal increases.
[0230]
The projection display device of the present invention uses three display panels of the present invention for modulating red, blue and green as light valves. As described above, when the resin component of the mixed solution is polymerized, the display panel changes the irradiation intensity of the ultraviolet rays so as to obtain an optimum average particle diameter or average pore diameter for each wavelength of light to be modulated. .
[0231]
A problem arises when three colors of red, blue and green are modulated by one display panel. Specifically, this is a case where a mosaic color filter corresponding to the pixel is provided. Good display contrast cannot be expected unless the average particle size is optimized for each pixel electrode. Therefore, it is difficult to polymerize the resin component of the mixed solution by uniformly irradiating ultraviolet rays.
[0232]
The configuration shown in FIG. 57 solves this problem. A color filter 471 is disposed on the pixel electrode 151. For ease of explanation, in the transmissive display panel, the color filter 471a is red, 471b is green, and 471c is blue. A dielectric thin film 472 is formed on the counter electrode 88 by patterning. The formation of the thin film 472 substantially matches the shape of the pixel electrode 151. Since the dielectric thin film 472 is used as an ultraviolet absorbing means, it is not limited to the dielectric thin film. For example, ITO may be formed thick and used as an ultraviolet absorbing means. Of course, the dielectric thin film includes an inorganic material such as TiO 2 and an organic material such as polyimide and PVA.
[0233]
Examples of the shape material of the dielectric thin film 472 include TiO 2 and SiO. The refractive index n of TiO2 is 2.3, and the refractive index n of SiO is 1.7. Both materials absorb light with wavelengths in the ultraviolet region and transmit visible light. However, since the wavelength band to be absorbed and the absorptance change depending on the deposition conditions, it is necessary to repeat the experiment to set. As an example, according to an experiment, in the case of TiO2, when the physical film thickness of the film is 0.075 μm, the light absorption rate is 40% for light having a wavelength of 350 nm, 37% for 360 nm, 30% for 370 nm, It was 16% at 380 nm, and there was almost no absorption in visible light. Since SiO may absorb visible light to some extent, TiO2 is preferred in this sense.
[0234]
The dielectric thin film 472a on the red filter 471a is the thickest, the dielectric thin film 472b on the green filter 471b is thinner, and no dielectric thin film is formed on the blue filter 471c. Accordingly, when the mixed solution is polymerized, if the ultraviolet ray is irradiated from the A direction, the intensity of the ultraviolet ray incident on the liquid crystal layer 87c is the strongest, then becomes the liquid crystal 87b, and the liquid crystal 87a becomes the weakest. The average particle diameter of the water droplet-shaped liquid crystal 181 increases as the ultraviolet light is weaker. This is the same as increasing the average pore size of the polymer network. That is, the PD liquid crystal is not limited to the liquid crystal having water droplet liquid crystal.
[0235]
Due to the difference in the ultraviolet absorption rate of the dielectric thin film 472 described above, the average particle diameter of the water droplet-like liquid crystal 181 of the liquid crystal layer 87 is
Liquid crystal layer 87a> Liquid crystal layer 87b> Liquid crystal layer 87c
It becomes. The wavelength of light that is optimally scattered and modulated with respect to the average particle diameter of the liquid crystal layer 87 is in a substantially proportional relationship. As shown in FIG. 57, a favorable display contrast can be obtained by setting the optimum average particle diameter for the light of the color filter.
[0236]
The average particle diameter of the polymer network or the average particle diameter of the water droplet liquid crystal is 1.2 to 1.6 μm when the light to be modulated is red light, 1.0 to 1.4 μm when the light is green, and blue light. In this case, the display contrast is good when the thickness is 0.8 to 1.2 μm. The average particle diameter is controlled by the film thickness of the dielectric thin film 472, and the film thickness is determined after sufficient experiments. As described above, a configuration in which the average particle diameter or the like of the water droplet liquid crystal is changed for each pixel with the dielectric thin film 472 or the like is called a particle diameter changing structure.
[0237]
In FIG. 57, the low dielectric film 231 is formed on the source signal line 154 and the like, but other low dielectric pillars 562 may be used as shown in FIG. Needless to say, the light shielding column 261 may be used. 24, the polarizing plate structure using the polarizing plate 331 as shown in FIG. 36, the convex structure shown in FIG. 53, the light shielding film structure shown in FIG. It goes without saying that the effects associated with each structure can be enjoyed if the TFT light shielding structure shown is employed as needed. Note that these configurations and structures are also applied to a reflective display device described later.
[0238]
In FIG. 57 and the like, the low electric field film 231 is formed to prevent the transverse electric field. However, as shown in FIG. Also good. Since the source signal line 154 and the like are only covered at the same time when the color filter 471 is formed, it is easy to manufacture. The color filter is a resin material and has a relatively low relative dielectric constant, and can provide the same effect as the low dielectric film 231.
[0239]
When irradiating the mixed solution with ultraviolet rays, when the extremely strong light is irradiated, the average particle size of the water droplet-like liquid crystal becomes very small. If it becomes extremely small, even if a voltage is applied, it will not be in a transmission state. For example, when the average particle size is 0.6 μm or less, the voltage at which the transmission state is obtained is close to 10V.
[0240]
The liquid crystal layer on the pixel electrode 154 is normally in a transmissive state at a voltage of 6 V or less. If it is a specification that becomes a transmission state at 10V, it is a scattering state at 6V. In the scattering state, the display is black. Therefore, the same effect as that of pseudo BM is obtained.
[0241]
In the structure shown in FIG. 59, the liquid crystal layer 87 such as the source signal line 154 is always in a scattering state as described above, and the pseudo BM is obtained. The dielectric thin film 472 is not formed on the counter electrode 88 facing the source signal line 154, and the dielectric thin film 472 is formed on the counter electrode 88 facing the pixel electrode 151. The dielectric thin film 472a facing the red color filter 471a is the thickest, the dielectric thin film 472b facing the green color filter 471b is the next thinnest, and the dielectric thin film 472c facing the blue color filter 471c is the thinnest. Therefore, when irradiating with ultraviolet rays, the energy of the ultraviolet rays incident on the liquid crystal layer 87 is
Liquid crystal layer 87a <liquid crystal layer 87b <liquid crystal layer 87c <liquid crystal layer 87d
To. Due to the difference in energy of the ultraviolet rays, the average particle size and the like of the water droplet liquid crystal in the liquid crystal layer is
Liquid crystal layer 87a> Liquid crystal layer 87b> Liquid crystal layer 87c> Liquid crystal layer 87d
It becomes. At this time, the liquid crystal layers 87a, 87b, and 87c are made transparent at a voltage of 6V, and the liquid crystal layer 87d is made not to be in a transmissive state unless it is close to 10V. In this way, the configuration in which the liquid crystal layer 87d other than the pixel electrode does not respond to the voltage is called a pseudo BM structure.
[0242]
As described above, as shown in FIG. 59, if the average particle diameter or the like of the water droplet-like liquid crystal on the source signal line and the gate signal line is very small, no response is made to voltage application. The same effect as that obtained when the low dielectric column 262 is formed on the source signal line 154 or the like can be obtained. That is, if the average particle size is very small, it does not respond to a transverse electric field. Therefore, light leakage from the pixel peripheral portion and the like is eliminated. Moreover, since it is always in a scattering state, the same effect as that obtained by forming the BM can be obtained. As a matter of course, the low dielectric pillar 262 may be formed as shown in FIG.
[0243]
57 to 60, the color filter 471 is formed on the pixel electrode 151 and the dielectric thin film 472 is formed on the counter electrode 88. Conversely, on the pixel electrode 151 or the pixel electrode 151, Needless to say, the dielectric thin film 472 may be formed in the lower layer, and the color filter 471 may be formed on the counter electrode 88 or in the lower layer. In that case, when the resin component of the mixed solution is polymerized, the ultraviolet rays may be irradiated from the direction B in FIG.
[0244]
Hereinafter, embodiments of the reflective display device of the present invention will be described. The description will focus on matters different from the transmission type. Thus, the previously described transmissive configuration applies. FIG. 61 is a block diagram of a reflective liquid crystal display device of the present invention. The thickness of the glass substrate as the counter substrate 161 is 0.6 to 1.1 mm. A TFT 86 and the like are formed on the array substrate 161. A reflective electrode 372 is formed on the TFT 86 via an insulating film 374. The reflective electrode 372 and the TFT 86 are electrically connected by a connection terminal 373. As a material of the insulating film 374, an organic material typified by polyimide or the like, or an inorganic material such as SiO 2 or SiN x is used. The reflective electrode 372 has a surface made of an Al thin film. Although it may be formed using Cr or the like, the reflectance is lower than Al, and since it is hard, the peripheral portion of the reflective electrode 372 is easily broken.
[0245]
Although the connection terminal portion 373 can be depressed by 0.5 to 1 μm, there is no problem because processing such as alignment of the PD liquid crystal 87 is unnecessary. The aperture ratio is 80% or more when the pixel size is 100 μm square, and 70% or more even when the pixel size is 50 μm square. However, unevenness occurs on the TFT 86 and the like, and the reflection efficiency slightly decreases. In order to eliminate the unevenness, the surface of the reflective electrode 372 may be polished. The reflectance can achieve 90% or more by polishing.
[0246]
The source signal line 154 and the gate signal line 153 are not shown, but are formed on the array substrate 162. Since the reflection line 372 covers the signal line and the TFT 86, the liquid crystal 87 is not aligned by the electric field generated from the signal line and the TFT 86, and image noise is not generated.
[0247]
In the transmissive display panel, the horizontal electric field is mainly generated between the signal line and the pixel electrode 151. In the reflective display panel, the signal line 154 and the like are formed below the reflective electrode 372, so that a horizontal electric field is hardly generated between the signal line 154 and the reflective electrode 372. However, a horizontal electric field is generated between adjacent pixels. That is, as shown in FIG. 62, when a reflective electrode 372d has a positive polarity and a negative polarity voltage is applied to the reflective electrodes 372b, 372c, 372e, an electric field line (lateral electric field) 263 is applied between the reflective electrodes 372b and 372d. Will occur. The liquid crystal molecules 281 are aligned along the lateral electric field 263. A lateral electric field is not generated between the reflective electrodes 372b and 372e. This is because the reflective electrodes have the same polarity.
[0248]
As shown in FIG. 62, when the long axes of the liquid crystal molecules 281 are aligned in the direction of the lateral electric field 263, the polarized light in the bb ′ direction is transmitted and scattered in the polarized light in the aa ′ direction. In order to prevent light leakage due to a transverse electric field using a polarizing plate, the polarizing axis 332 of the polarizing plate 331 may be set in the aa ′ direction.
[0249]
However, the reflection type liquid crystal display panel does not cause a phenomenon that light is transmitted through the periphery of the pixel electrode unlike the transmission type liquid crystal display panel. In the reflective type, the liquid crystal around the reflective electrode appears as a phenomenon that causes irrelevant display (hereinafter referred to as image noise) in video display. That is, the horizontal electric field 263 causes the liquid crystal layer to be in a transmissive state, and light incident on the transmissive portion is reflected by the reflective electrode and projected on the screen.
[0250]
In order to further prevent the lateral electric field generated between the pixel electrodes, the low dielectric film 231 may be formed between the reflective electrodes 372. The low dielectric film thickness 231 is formed between the reflective electrodes and around the reflective electrode. The formation material and effects of the low dielectric film 231 have been described with reference to FIG. Further, it has already been described with reference to FIG. 29 that the low dielectric film 231 can be colored to prevent halation between the liquid crystal layers 87. Further, the low dielectric film 231 may be a light shielding column 262 as shown in FIG.
[0251]
FIG. 63 shows a reflection type PD liquid crystal display panel adopting a particle diameter changing structure. Since the structure of the transmissive display panel shown in FIG. 60 and the like is adopted as a reflection type, no particular explanation is required. Irradiation with ultraviolet rays may be performed from the A direction. Dielectric multilayer films 371a and 371b are laminated on both surfaces of the counter electrode 371b to form an antireflection film 371. The antireflection film 371 has a three-layer configuration including a first dielectric thin film 371a, an ITO thin film 371b as a counter electrode, and a second dielectric thin film 371c in this order from the counter substrate 161 side. Transparent dielectric thin films 371a and 371c are formed before and after the ITO thin film serving as the counter electrode 371b to form a three-layer structure and have an antireflection function. The optical film thickness (nd) of the ITO thin film 371b is λ / 2, and the optical film thicknesses of the first thin film 371a and the second thin film 371c are λ / 4. Where n is the refractive index, d is the physical film thickness, and λ is the wavelength of light.
[0252]
In the liquid crystal display panel 81 shown in FIG. 61 and the like, a TFT 86 is formed below the reflective electrode 372. That is, the reflective electrode 372 has a function of a light shielding film (BM) for preventing incident light scattered by the PD liquid crystal layer 87 from entering the semiconductor layer of the TFT 86 and a function as an electrode for applying a voltage to the liquid crystal layer 87. I have a match. Since the reflective electrode 372 is formed of a metal material, has a sufficient light shielding effect, and has a simple structure, cost reduction can be realized.
[0253]
The reflective electrode 372 and the TFT 86 are electrically connected by a connection portion 373. In order to establish a connection, it is necessary to deposit a metal thin film (reflecting electrode) 372 over the thickness of the insulating film 374. The thickness of the insulating film 374 is about 1 μm. Therefore, a step of 1 μm occurs at the connection portion 373. Further, since the thickness of the reflective electrode 372 is also 1 μm, a 1 μm valley is formed between the adjacent reflective electrodes. Since the PD liquid crystal display panel does not require rubbing, the liquid crystal display panel can be manufactured with a high manufacturing yield without any obstacles even if the step is present.
[0254]
The connection terminal portion 373 has a step of 1 μm. In addition, the shape of the TFT 86 is patterned on the reflective electrode 372, and unevenness of about 1 μm is generated. The PD liquid crystal display panel performs light modulation as a change in the scattering state. Therefore, a change of about 1 μm in the liquid crystal film thickness due to the step and the unevenness of the TFT 86 hardly affects the light modulation. In a display panel in which the light application characteristic is applied to light modulation such as TN liquid crystal, the unevenness will be fatal to light modulation. Further, the fact that the liquid crystal film thickness of the PD liquid crystal display panel is as thick as 8 μm or more acts in a good direction against the film thickness unevenness of the liquid crystal layer 87.
[0255]
The refractive index of the first thin film and the second thin film is preferably 1.60 or more and 1.80 or less. Examples are SiO, Al2O3, Y2O3, MgO, CeF3, WO3, and PbF2. In particular, when the first thin film is made of SiO and the second thin film is made of Y 2 O 3, an excellent antireflection effect of 0.1% or less over the entire visible light region can be realized.
[0256]
In the antireflection film 371, the optical film thickness of the first and second dielectric thin films is λ / 4 and the optical film thickness of the ITO thin film is λ / 2. The optical film thickness of the thin film may be λ / 4, and the optical film thickness of the ITO thin film may be λ / 4.
[0257]
Further, in terms of the theory of the antireflection film, when N is an odd number of 1 or more and M is an integer of 1 or more, the optical film thickness of the first and second dielectric thin films is (N · λ) / 4. The optical film thickness of the ITO thin film may be (N · λ) / 4. Alternatively, the optical film thickness of the first and second dielectric thin films may be (N · λ) / 4, and the optical film thickness of the ITO thin film may be (M · λ) / 2.
[0258]
Furthermore, one of the first and second dielectric thin films can be omitted. In that case, the performance as an antireflection is somewhat lowered, but it is often sufficient in practice. Also in this case, the above theory of antireflection can be applied.
[0259]
By forming the antireflection film 371, it is possible to prevent the reflected light without entering the liquid crystal layer 87, so that the display contrast can be greatly improved. Further details are described in Japanese Patent Application No. 5-109232. As for the configuration and the like of these antireflection films 371, the description in the above publication is applied to this specification.
[0260]
A reflective display panel can display high luminance because it has a thin liquid crystal 87 film thickness, good contrast, and a high pixel aperture ratio, compared to a transmissive display panel. In addition, since there is no obstacle on the back surface of the display panel, the panel can be easily cooled. For example, forced air cooling and liquid cooling can be easily performed from the back surface, and a heat sink 381 and the like can be attached to the back surface as shown in FIG. The heat sink 381 is used by being attached to the display panel 81 with an adhesive 282 such as silicon.
[0261]
In the display device of the present invention, the light reflected by the interface 455 is scattered or absorbed by the convex structure shown in FIG. 55 or the lower light-shielding film structure shown in FIG. By adopting a configuration (hereinafter referred to as a transparent member structure) in which a concave lens or a transparent substrate (hereinafter collectively referred to as a transparent member) is attached to the light incident / exit surface of the display panel 81, the ghost or the like can be prevented. Further, the display contrast can be improved. In addition, the transparent member structure can exhibit a unique effect that can improve display contrast and the like when used alone, and the effect is further enhanced by combining with the lower light-shielding film structure and the convex structure. Hereinafter, the transparent member structure will be described.
[0262]
FIG. 65 shows a configuration in which a transparent member or the like is attached to the display panel of the present invention. A transparent substrate 391 is attached to the surface of the display panel. The transparent substrate 391 is attached to the surface of the display panel via the optical coupling layer 392. An antireflection film (not shown) for preventing light reflected at the interface with air is formed on the surface of the transparent substrate 391. For example, the V coat described above.
[0263]
As the optical coupling layer, an ultraviolet curable adhesive is exemplified. Many of the adhesives are close to the refractive index of the glass substrate constituting the display panel, and are suitable for use as an optical binder. Moreover, it is not limited only to an ultraviolet curable adhesive, A transparent silicone resin etc. can also be used. In addition, liquids such as epoxy-based transparent adhesives and ethylene glycol can also be used. It should be noted that air does not enter between the counter substrate 161 and the like of the display panel. In the presence of air, image quality abnormalities occur due to refractive index differences.
[0264]
The transparent substrate 391 is made of a transparent material such as glass or acrylic resin, and a non-display area (called an ineffective surface) other than the effective display area is provided with a light absorption film (not shown) by black paint or the like. Is formed.
[0265]
The reason why the display contrast and the like can be improved by attaching the transparent substrate 391 to the display panel is described in detail in Japanese Patent Application Laid-Open No. 4-145277, and the description thereof is omitted here. All matters described in the above publication are applied to this specification.
[0266]
Many configurations are possible in which a transparent member is attached to the display panel of the present invention. For example, as shown in FIG. 13 of the above publication, a configuration in which the concave lens 112 is pasted on the display panel, a configuration in which the concave lens 112 is pasted, and a convex lens is disposed in the concave portion of the concave lens via a slight air layer, or transparent There is a substrate 111. These matters are also described in the publication.
[0267]
As shown in FIG. 66, when the transparent substrate or the concave lens is attached to the display panel, the light scattered by the liquid crystal layer 87 is reflected by the interface 455, and the liquid crystal layer 87 is scattered again (secondary scattering or secondary light source). Therefore, the display contrast can be improved. The fact that the light reflected by the interface 455 is not returned to the liquid crystal layer 87 again means that the light 453b reflected by the source signal line 154 and the like is also eliminated. That is, as shown in FIG. 46, the incident light 451 is scattered by the liquid crystal layer 87 and becomes the scattered light 452, but the light is reflected by the interface 455 of the concave lens 391, and light absorption formed entirely in the ineffective region of the concave lens. It is incident on the film and absorbed.
[0268]
In the case where the polarizing plate 331 is attached to the display panel, it is preferable to sandwich the polarizing plate 331 between the transparent substrate 391 and the counter substrate 161 as shown in FIG. Although the polarizing plate 331 may be affixed to the surface which contacts the transparent member 391 and air, since the polarizing plate 331 is usually a resin film, it is difficult to form an antireflection film on the resin film surface. Without the antireflection film, the light reflected at the interface 455 increases and light loss occurs. If sandwiched between the transparent member 391 and the counter substrate as shown in FIG. 65, no light is reflected on the polarizing plate 331, and an antireflection film can be formed on the interface of the transparent member 391, so that the light utilization rate can be improved. . Note that the polarization axis 332 of the polarizing plate 331 is set in consideration of the generation direction of the transverse electric field, as described with reference to FIG.
[0269]
The transparent member structure can also be applied to the reflective display panel of the present invention. FIG. 67 is a configuration diagram thereof. On the surface of the transparent member 391a, a three-layer multi-coat antireflection film 401 is formed. Of course, as shown in FIG.
[0270]
The transparent part plate (transparent substrate, concave lens) is not limited to a solid material such as glass or acrylic. For example, a cubic container or the like filled with a liquid such as ethylene glycol is included. Since the liquid is fluid, it has the effect of absorbing the heat of the liquid crystal panel and cooling the liquid crystal panel. That is, the transparent member has a function of cooling the liquid crystal panel heated by light as well as controlling the secondary scattered light.
[0271]
Many variations of the configuration of the reflective display panel can be considered as in FIG. For example, as shown in FIG. 67, a configuration in which the transparent substrate 391 is attached to the counter substrate 161 of the reflective display panel, a configuration in which a concave lens is attached instead of the transparent substrate, or the counter substrate 161 is sufficiently thick (the counter substrate Of the transparent substrate 391). These effects are also the same as those of the transmissive display panel shown in FIG. Further, as shown in FIG. 68, the polarizing plate 331 may be held between the counter substrate 161 and the transparent member 391.
[0272]
The reflective display device shown in FIG. 61 has a configuration employing a metal thin film 372. However, as the reflection type, the types illustrated in FIGS. 69 and 70 are also conceivable.
[0273]
FIG. 69 shows a configuration in which a light absorption film 771 is arranged under the pixel electrode 151 in the configuration of FIG. As the light absorbing film 771, a resin containing a black dye is exemplified. Other examples include black metal materials such as hexavalent chromium. However, it is desirable to adopt a light absorption film made of a resin in consideration of ease of production and color selection.
[0274]
The light absorption film 771 is patterned corresponding to the pixel shape. It is not commonly formed (integrated) for all pixels. This reason is due to restrictions on the manufacturing process of the TFT array. First, the TFT 86, the signal line 154, and the like are formed on the substrate 162. Next, a light absorption film 771 is applied with a spinner or the like, and then patterned in accordance with the pixel shape. Finally, ITO which becomes the pixel electrode 151 is deposited, and the ITO is patterned to become the pixel electrode 151.
[0275]
In order to deposit a metal thin film constituting the TFT 86 and the like, it is necessary to heat the substrate 161 to a relatively high temperature. At the temperature, the resin of the light absorption film 771 deteriorates or changes. Therefore, the TFT 86 cannot be formed after the light absorption film 771 is formed. Therefore, a light absorption film 771 is formed after the TFT 86 is formed. Further, drilling (patterning) for connecting the TFT 86 and the pixel electrode 151 is performed. Although not shown in the drawing, a light absorption film 771 is formed on the signal line 154 and the like. This is because the light absorption film 771 functions as the low dielectric film 241 or the light absorption film 231 to prevent a horizontal electric field between the signal line and the pixel electrode.
[0276]
When the pixel electrode 151 is viewed from the A direction, it appears white (scattered) when the liquid crystal layer 87 is in a scattering state. When the liquid crystal layer 87 is in a light transmitting state, the black light absorbing film 771 can be seen. That is, the light transmittance is controlled for each pixel by the TFT 86, so that a black and white image or characters can be displayed. 69 does not use a light source or the like, and can display characters, graphics, and the like under illumination of direct light or artificial light such as a fluorescent lamp. Therefore, low power consumption can be realized and it is suitable for a monitor such as a pocket computer. Of course, if the light absorbing film 771 reflects red light, green light, and blue light, full color display can be performed. This is a matter that can be realized only by adopting a PD liquid crystal. This is because a TN liquid crystal needs to use a polarizing plate, and a practically sufficient display luminance cannot be obtained. The configuration of the light shielding film 156 and other antireflection films 371 and the like have been described with reference to FIG.
[0277]
A configuration of FIG. 70 in which the reflection type of FIG. 61 is modified is also conceivable. The configuration in FIG. 70 is a configuration in which the reflective electrode 372 in FIG. 61 is a transparent electrode 151 and the insulating film 374 is a light absorption film 771. That is, when the liquid crystal layer 87 is in a light transmission state, the color of the light absorption film 771 under the ITO 151 can be seen as shown in FIG.
[0278]
The TFT 86 is formed below the ITO 151. By forming in this way, the pixel aperture ratio is improved. However, the light absorption film 771 may contain an impurity such as an alkali metal and may affect the characteristics of the TFT 86. Therefore, a protective film 781 made of an inorganic material such as SiO 2 or SiN x is formed on the TFT 86. First, the TFT 86, the signal line 154, and the like are formed on the substrate 162. Next, a protective film 781 is formed on the TFT 86. Thereafter, a light absorbing film 771 is applied with a spinner or the like, and then patterned in accordance with the pixel shape. Finally, ITO to be the pixel electrode 151 is deposited and patterned to form the pixel electrode 151.
[0279]
Further, a light absorption film 231 is formed between adjacent ITOs 151. This is because the region where the light modulation is not in the normal display state is visually invisible due to the horizontal electric field generated between the pixels.
69 and 70, an insulating film 232 is preferably formed on the counter electrode 88 and the ITO electrode 151. The reason for this will be omitted since it has been explained previously. Further, the configuration and material of the liquid crystal layer 87 have already been described, and therefore will be omitted.
[0280]
32 to 34 and FIG. 61, the liquid crystal molecules have been described as having a positive dielectric constant. Therefore, when the lateral electric field is generated in the direction aa ′, the liquid crystal molecules are aligned in the direction aa ′. Therefore, the polarized light in the bb ′ direction is easily transmitted.
[0281]
However, when the liquid crystal molecules have a negative dielectric constant, the above relationship is reversed. In the case of having a negative dielectric constant, when a transverse electric field is generated in the aa ′ direction, it can be regarded as equivalent to being oriented in the bb ′ direction. Therefore, the polarized light in the aa ′ direction is easily transmitted. When the liquid crystal molecules have a positive dielectric constant, as shown in FIG. 62, when the video signal display method of the present invention is performed, polarized light in the aa ′ direction is easily transmitted. Therefore, when a polarizing plate is used in the display device of the present invention, the polarizing axis of the polarizing plate is made to substantially coincide with the pixel column direction (bb ′ direction). In the case of column inversion driving, the polarization axis of the polarizing plate is made to coincide with the pixel row direction (aa ′ direction).
[0282]
The description in this specification (including claims) describes that liquid crystal molecules have a positive dielectric constant. Actually, most liquid crystals that are practically used have a positive dielectric constant. However, a liquid crystal having a negative dielectric constant may be used. Therefore, when a liquid crystal having a negative dielectric constant is used, the description in the specification of the present invention (including the claims) needs to be replaced. Specifically, when the liquid crystal has a negative dielectric constant, the polarization axis of the polarizing means is set to the pixel row method (the formation direction of the gate signal line) when performing H inversion driving, and the polarization is applied when performing column inversion driving. The polarization axis of the means is the pixel column method (source signal line forming direction).
[0283]
One technical idea of the present invention is that a liquid crystal molecule is aligned in a horizontal electric field to prevent light leakage from the periphery of the pixel electrode and the like. Configuration or driving method. For example, the direction of the polarization axis, the low dielectric column 261, the light shielding film 211, the resin light shielding film 231, the low dielectric film 241, the light shielding column 262, the driving method (H inversion driving, column inversion driving), and the like. Accordingly, if the liquid crystal has a negative dielectric constant, the alignment direction of the liquid crystal molecules due to the transverse electric field is also different, so that the specification and the claims are naturally adapted to the case of the negative dielectric constant. Must be read as This is because there is no change in the technical idea intended by the present invention.
[0284]
The projection display device of the present invention will be described below. The projection display device of the present invention basically uses the display device 81 of the present invention as a light valve. First, items common to the projection display apparatus of the present invention will be briefly described.
[0285]
In the projection display device of the present invention, from the viewpoint of improving the light utilization rate, if the panel effective display size (panel display area) is reduced, the F number of the illumination light needs to be increased. If the panel effective display size d is increased, the F number of the illumination light can be reduced, and as a result, a bright large screen display can be realized. However, when the panel effective display size is increased, the system size of the projection display device is increased, which is not preferable. Moreover, if the panel effective display size is reduced, the luminous flux per unit area incident on the display area of the panel is increased, which is not preferable because the panel is heated.
Further, when the luminous body luminance is fixed at 1.2 × 10 8 nt in consideration of the lamp life, the arc length and the power consumption of the lamp are considered to be approximately proportional. The efficiency of the metal halide lamp is 80 lm / W. The total luminous flux of the 50 W lamp is 4000 lm, the total luminous flux of the 100 W lamp is 8000 lm, and the total luminous flux of the 150 W lamp is 12000 lm. There is a correlation between the arc length of the lamp and the lamp power consumption, and there is a correlation between the arc length and the F number.
[0286]
In the projection display device, a light beam of 300 to 400 lm or more is required in order to obtain a projection image with a screen size of 40 inches or more and a practical viewing angle and image brightness. Therefore, if the light utilization factor of the lamp is about 4%, a lamp of 100 W or more must be used. For this reason, a lamp with an arc length of 3 mm can be used only to obtain a good display contrast (CR), but a metal halide lamp of 100 W or more is necessary to obtain sufficient brightness of the projected image. .
[0287]
Also, if the panel effective display size is small, sufficient display brightness cannot be obtained. The effective display size of the panel needs to be about 3.5 inches when the arc length is 5 mm and the effective F value of illumination light is 7. If the arc length is about 5 mm and the panel effective display size is a little over 2 inches, the effective F value of the illumination light is a little less than 5. In this case, the display luminance is in a practical range, but good display contrast (CR) cannot be expected.
[0288]
As a result of various experiments and studies, if the effective F value of the illumination light is 5 or more, display luminance in a practical range can be obtained. However, in order to obtain good display brightness and display contrast, proper power consumption and lamp life, the effective F value of illumination light (= the effective F value of projection light) is around 7, the arc length of the lamp is around 5 mm, the lamp The result is that W of around 150W should be used.
[0289]
When the F number of the projection lens is lowered, the screen light flux that reaches the screen increases. Along with this, the power consumption of the lamp must be increased. Further, when the power consumption of the lamp is increased from the viewpoint of extending the lamp life, the arc becomes long when the arc luminance is assumed to be constant. Naturally, the display contrast (CR) becomes worse as the F number becomes smaller. Conversely, when the F number of the projection optical system is increased, the display contrast is increased, but the screen luminous flux is decreased.
[0290]
As a result of various experiments and examinations, the power consumption must be 250 W or less. In order to obtain screen brightness, a metal halide lamp of 100 W or more must be used. More preferably, the arc length should be not less than 3 mm and not more than 6 mm in consideration of screen brightness and display contrast.
[0291]
The diagonal length of the effective display area of the panel must be no more than 4.5 inches in terms of system size. Moreover, it must be 2 inches or more from the point of light utilization efficiency. In particular, in order to obtain a sufficient light collection efficiency and to be compact, it is necessary to set it to 3 inches or more and 4 inches or less.
[0292]
If the panel size (effective diagonal table) is d (inch) and the arc length L (mm) of the lamp, the following relationship is preferably satisfied.
2 / 3d ≦ L ≦ 2d
For example, if the panel size d is 3 inches, the arc length L is 2 mm or more and 6 mm or less.
[0293]
The F number of the projection lens, in a broad sense, the F number of the projection optical system must be 5 or more in order to obtain a good contrast (CR). Also, it must be 9 or less in order to obtain sufficient screen brightness. Further, in consideration of the arc length of the lamp, the F number must be 6 or more and 8 or less.
[0294]
In addition, the light utilization rate is reduced unless the light spread angle (F number) of the illumination light is substantially matched with the light collection angle (F number) of the projection lens. This is because the F number is limited. The F number of the illumination light of the projection display device of the present invention and the F number of the projection lens are matched.
[0295]
In the above description, for example, the lamp arc length of 5 mm means “substantially 5 mm”. Substantially 5 mm means that even if the arc length is 8 mm, if the projection lens can collect only the light emitted from around 5 mm in the center of the arc among the light emitted from the arc, The arc length is 5 mm. Similarly, the F number means an effective F number. Even if the physical F number is 4, if the light passes only near the center of the pupil of the projection lens, the F number is naturally 4 or more.
[0296]
In the projection display device of the present invention, the display device 81 of the present invention is used as a light valve. 71 and 72 show the configuration of the projection display device of the present invention. However, components that are not necessary for the description are omitted. In FIG. 71, reference numeral 521 denotes a light source, in which a concave mirror 521b and a metal halide lamp or xenon lamp as light generating means 521a are arranged. A UVIR cut filter 521c is disposed in front of the concave mirror 521b. The UVIR cut filter 521c reflects infrared light (IR) and ultraviolet light (UV) and transmits visible light. 523a is a BDM that reflects B light, 523b is a GDM that reflects G light, and 523c is an RDM that reflects R light. The arrangement of BDM 523a to RDM 523c is not limited to the order shown in FIG. Needless to say, the last RDM 523c may be replaced with a total reflection mirror. The relay lens 522 corrects the difference between the optical path length from the light source 521 to the display device 81c that modulates the R light and the optical path length to the display device 81a that modulates the B light. In the projection display device of the present invention, the display device 81 of the present invention is mainly used as a light valve. (The optical system of FIG. 71 and three projection lenses are shown as 702 and 524 in the cabinet 701 in the apparatus shown in FIG. 72. The projected light is reflected by the mirrors 531a and 531b and is reflected on the screen 542. Projected.)
[0297]
When PD liquid crystal is used for the light modulation layer 87, the light modulation layer that modulates R light has a larger water droplet-like liquid crystal particle diameter than other light modulation layers that modulate G and B light, or a liquid crystal film. Configure with a thicker thickness. This is because the longer the wavelength of light, the lower the scattering characteristics and the lower the contrast. The particle size of the water droplet liquid crystal can be realized by controlling the ultraviolet light during polymerization, changing the material used, or adopting the particle size changing structure described with reference to FIG. The film thickness of the liquid crystal 87 can be adjusted by changing the bead diameter of the liquid crystal layer. Reference numeral 524 denotes a projection lens, reference numerals 525 and 227 denote lenses, and reference numeral 526 denotes an aperture as an aperture. The aperture 526 is shown for explaining the operation of the projection display device. Since the aperture 526 defines the condensing angle of the projection lens 524, it can be considered as being included in the function of the projection lens. That is, if the F value of the projection lens 524 is large, it can be considered that the hole diameter of the aperture 526 is small.
[0298]
In order to obtain a high contrast display, it is better that the F value of the projection lens is larger. However, as the F value increases, the brightness of white display, that is, the screen brightness decreases. On the other hand, when the F value is decreased, the screen brightness is increased and high brightness display is possible, but the display contrast is lowered. When a metal halide lamp with an arc length of 5 mm is used, the F value is 5 or more and 9 or less. The F value is preferably around 7. If it is around 7, display contrast is good and sufficient display brightness can be obtained.
[0299]
The operation of the projection display device of the present invention will be described below. Since the modulation systems for R, G, and B light are substantially the same, the modulation system for B light will be described as an example.
[0300]
White light is emitted from the light source 521, and the B light component of the white light is reflected by the BDM 523a. This B light is incident on the display device 81a. As shown in FIG. 23, the display device 81 modulates light by controlling the scattering and transmission state of incident light according to a signal applied to the pixel electrode 151.
[0301]
The scattered light is blocked by the aperture 526a, and conversely, the parallel light or the light within a predetermined angle passes through the aperture 526a. The modulated light is enlarged and projected on a screen (not shown) by the projection lens 524a. As described above, the B light component of the image is displayed on the screen. Similarly, the display device 81b modulates the G light component light, and the display device 81c modulates the R light component light to display a color image on the screen.
[0302]
A drive circuit and drive method for a projection display apparatus when three light valves that modulate red, green, and blue light are used will be described. FIG. 17 is an explanatory diagram of a drive circuit in an example of the projection display apparatus according to the present embodiment. Here, R1 and R2 and the transistor Q constitute a phase division circuit 142 that creates a positive and negative video signal of the video signal input to the base. Reference numeral 143 denotes an output switching circuit that outputs an AC video signal having a polarity inverted every horizontal scanning period (H) or one vertical scanning period (1 V) to the display device 81.
[0303]
The video signal is gain-adjusted to a predetermined value and then divided into signals corresponding to R, G, and B light. The divided video signals are referred to as a video signal (R), a video signal (G), and a video signal (B), respectively. Video signals R, G, and B are each input to a phase division circuit, and two positive and negative video signals are generated by this circuit. Next, the two video signals are input to the respective output switching circuits 143a, 143b, 143c, and the output switching circuit switches the polarity of the output signal every 1H or 1V. Next, the video signal from each output switching circuit 143 is input to the source drive circuit 33 shown in FIG. The drive control circuit 141 synchronizes the source drive circuit 33 and the gate drive circuit 38 and displays an image on the display panel 81.
[0304]
Next, the visibility of human eyes will be described. The human eye has the highest sensitivity around the wavelength of 550 nm. Of the three primary colors of light, green is the highest, next is red, and blue is the least sensitive. In order to obtain a luminance signal proportional to the sensitivity, 30% red, 60% green, and 10% blue may be added. Therefore, in order to obtain white in a television image, it is sufficient to add at a ratio of R: G: B = 3: 6: 1. Further, as described above, the liquid crystal needs to be AC driven. This AC driving is performed by alternately applying positive and negative signals to a voltage (hereinafter referred to as a common voltage) applied to the counter electrode of the display panel. In this embodiment, the positive polarity signal is applied to the display panel and the light having the intensity of visibility n is modulated by + n, and the negative polarity signal is applied and the light having the intensity of visibility n is modulated. -N is expressed as -n. For example, light of R: G: B = 3: 6: 1 is applied to the display panel, and a positive signal is applied to predetermined pixels of the R and B display panels (81c, 81a), and the pixels If a negative signal is applied to the pixel of the G display panel 81b that is overlaid on the G +, it is expressed as + 3 · −6 · + 1.
[0305]
Note that R: G: B = 3: 6: 1 is for NTSC television images, and in the projection display apparatus, the ratio varies depending on the light source lamp, the spectral characteristics of the dichroic mirror, and the like. In FIG. 17, it is indicated as + 3 · −6 · + 1. This is because, when attention is paid to one arbitrary image on each display panel superimposed on the same position on the screen, each pixel is irradiated with light of R: G: B = 3: 6: 1. This shows that a positive signal is applied to the pixels of the display panel and a negative signal is applied to the pixels of the G display panel 81b. Each pixel is in a signal application state expressed as −3 · + 6 · −1 after one field.
[0306]
Normally, even when the same signal is applied to the liquid crystal display panel 81, there is a slight difference in the voltage held in the pixels in the even field and the odd field. This occurs because the on-current and off-current of the TFT 86 differ depending on the video signal, or the difference in holding characteristics between the positive electric field and the negative electric field of the insulating film 372 or the like. This difference causes the phenomenon of flicker.
[0307]
However, in the projection display device of the present invention, as shown in FIG. 17, flicker is prevented from being visually seen by making the G light modulation signal have the opposite polarity to the R / B light modulation signal. it can. The reason why the G light modulation signal has a polarity opposite to that of the other is that the light intensity is R: G: B = 3: 6: 1 when the signal polarity and human vision are taken into consideration (R + B) : G = (3 + 1): 6 = 4: 6, so that the balance is approximately 4: 6 (ideally 5: 5 is good).
[0308]
For the reasons described above, the projection display apparatus of the present invention has been successfully displaying good images without visually recognizing flicker. Note that the above technical idea is not applied only to a projection display device using three display panels, but includes one display panel having a color filter as shown in FIGS. The present invention can also be applied to the projection display device used by making some changes. For example, a positive polarity voltage is applied to the R and B pixels and a negative polarity voltage is applied to the G pixel, and the voltage polarity applied for each frame is inverted.
[0309]
When the driving method shown in FIGS. 18 and 19 is performed, a display state as shown in FIG. 75 may be obtained. That is, a high luminance line (white line) and a low luminance line (black line) are displayed for each line or every two lines, and the white line seems to move slowly downward. The brightness (difference in transmittance) of the white line and the black line is slight. However, because each line is next to each other, it is a serious problem.
[0310]
This is considered to be because the amount of charge charged in the pixel 101 is different. For example, in FIG. 73, the pixel 101 in the first line is + a for 1F, + a1 for 2F, -c1 for 3F, -c1 for 4F, and + e1 for 5F. Focusing only on the voltage polarity, as shown in FIG. 73, “+” → “+” → “−” → “−” → “+”.
The pixel 101 is charged using a TFT 86. In {circle around (1)} in FIG. 73, the voltage polarity is the same because “+” → “+”. However, in (2), the voltage polarity is opposite because “+” → “−”. If the voltage polarity is the same, the amount of charge required for addition is small. Therefore, the driving capability of the TFT 86 may be small. However, if the voltage polarity is different, it is necessary to charge the charge of opposite polarity. Therefore, a large driving capability of the TFT 86 is required. This can be explained by the VT curve (voltage-transmittance characteristics) of the liquid crystal layer 87 in FIG. When the voltage polarity is opposite, the characteristic is a dotted line, and when the voltage polarity is the same, the characteristic is a solid line. That is, the transmittance is different between when the charge polarity of the pixel 101 is the same even when the same actual voltage (V) is applied, and when the charge polarity of the opposite polarity needs to be completely rewritten. It will end up. Therefore, as shown in FIG. 75, white lines and black lines (hatched portions) will be generated. Of course, when the charge retention rate of the pixel is high and the driving capability of the TFT 86 is sufficient, the phenomenon of FIG. 71 will hardly occur. However, in practice, there is a demand for reducing the size of the TFT 86 and increasing the pixel aperture ratio, and the phenomenon of FIG. 75 is likely to occur in many cases.
[0311]
Therefore, in the present invention, a data correction circuit 931 is added as shown in FIG. As an example, the data correction circuit 931 is arranged in the display line selection circuit of FIG. Alternatively, there is a configuration in which the frame memory shown in FIG. The data map 932 records the VT curve of FIG. 74 as a map. Specifically, it is a ROM. The (++) (−−) map is an area in which the solid line characteristic curve of FIG. 74 is mapped and stored. When data corresponding to the transmittance T is given from the data correction circuit 931, an actual operating voltage (data) corresponding to the solid line is output and transferred to the data correction circuit 931. That is, the voltage (data) applied to the pixel 101 when the polarity is “+” → “+”, “−” → “−” is corrected. On the other hand, the map for (+ −) (− +) is an area where the dotted characteristic curve of FIG. 74 is mapped and stored. When data corresponding to the transmittance T is given from the data correction circuit 931, an actual operating voltage (data) corresponding to the dotted line is output and transferred to the data correction circuit 931. The characteristic curve in FIG. 74 is measured in advance by experiments or the like, and stored in the data map 932 in ROM using the measured data.
[0312]
As described above, the transmittance data (or voltage data) from the line memory 41 is corrected by the data correction circuit 931, converted to an analog signal by the D / A converter 42, and output to the source signal processing circuit 32.
[0313]
In the projection display device using a plurality of liquid crystal display panels 81, the phenomenon shown in FIG. 75 can be more easily dealt with. As described with reference to FIG. 17, the voltage polarity applied to the pixels of at least one display panel 81 among the plurality of display panels 81 is reversed. In particular, it is preferable that the G light modulation panel has a polarity opposite to that of the R and B light modulation panels. This has been described with reference to FIG.
[0314]
As a voltage application method, the method is as shown in FIG. That is, in the panel 1 of FIG. 77 (a), two rows of the same polarity voltage are applied to the pixel 101 (from the upper end +++-++...), And in the panel 2 (FIG. 77 (b)). Apply every two lines as --- ++-.
[0315]
Also, the method of FIG. 78 may give better results. In panel 1 (FIG. 78 (a)), it is ++ −− ++ −−... From the upper end, and in panel 2 (FIG. 78 (b)), it is shifted by one line to be + −− ++ −−. By driving the display panel as shown in FIG. 78, the white line portion of the panel of FIG. 75 and the black line portion of the panel 2 are overlapped on the screen and can cancel each other. Of course, in the case of FIG. 77, the panel 1 and the panel 2 may be overlapped on the screen by shifting one line. As a matter of course, if the circuit configuration of FIG. 76 is adopted, the method of FIG. 77 or 78 need not be used. It goes without saying that even better results can be obtained by combining the circuit configuration of FIG. 76 with the method of FIG. 77 or 78.
[0316]
As described above, the projection display apparatus of the present invention applies the video signal display method described with reference to FIG. 12 to each display panel 81, and, as shown in FIG. The phase of the video signal applied to one liquid crystal display panel 81 is inverted. Therefore, no flicker occurs and a good display can be realized.
[0317]
Hereinafter, although the projection type display apparatus of other embodiment is demonstrated, the difference of a 1st Example is mainly demonstrated. Therefore, the items related to the display panel, the drive circuit, and the optical system described in FIG. 71 are also applied to other projection display devices as needed.
[0318]
71 and 72 show a method of enlarging and projecting on a screen by three projection lenses 524, but there is also a method of enlarging and projecting with one projection lens. FIG. 79 shows the configuration. Here, for ease of explanation, 81b is a display panel that displays an image of G light, 81c is a display panel that displays an image of R light, and 81a is a display panel that displays an image of B light. Therefore, the wavelength which transmits and reflects each dichroic mirror 531, the dichroic mirror 523a reflects R light and transmits G light and B light. The dichroic mirror 523b reflects G light and transmits R light. The dichroic mirror 523c transmits R light and reflects G light. The dichroic mirror 523d reflects B light and transmits G light and R light.
[0319]
Light emitted from a metal halide lamp (not shown) is reflected by the total reflection mirror 531a, and the traveling direction of the light is changed. The light is separated by the dichroic mirrors 523a and 523b into optical paths of the three primary colors of R, G, and B. The R light is incident on the field lens 532c, the G light is incident on the field lens 532b, and the B light is incident on the field lens 532a. . Each field lens 532 collects each light. The display panel 81 modulates the light by changing the orientation of the liquid crystal corresponding to each video signal. The R, G, B light modulated in this way is synthesized by the dichroic mirrors 523c, 523d, and enlarged and projected on the screen (not shown) by the projection lens 524.
[0320]
Hereinafter, an embodiment of a projection display device of the present invention using a reflective display device (display panel) 81 of the present invention as a light valve will be described with reference to FIG. The light source 521 emits light including color components of three primary colors of red (R), green (G), and blue (B). The concave mirror 521b is made of glass as described above, and is formed by depositing a multilayer film that reflects visible light and transmits infrared light on a reflection surface. Part of the visible light included in the emitted light from the lamp 521a is reflected by the reflecting surface of the concave mirror 521b. The reflected light emitted from the concave mirror 521b is emitted after the infrared rays and ultraviolet rays are removed by the filter 521c.
[0321]
The projection lens 524 includes a first lens group 524b on the liquid crystal display panel side and a second lens group 524a on the screen side, and a plane mirror 531 is disposed between the first lens group 524b and the second lens group 524a. ing. Scattered light emitted from the pixel at the center of the screen of the display panel 81 passes through the first lens group 524b, then enters about half of it into the plane mirror 531 and the rest does not enter the plane mirror 531. Incident to 524a. The normal line of the reflecting surface of the plane mirror 431 is inclined 45 ° with respect to the optical axis 541 of the projection lens 524. Light from the light source 521 is reflected by the plane mirror 531, passes through the first lens group 524 b, and enters the display panel 81.
[0322]
The reflected light from the display panel 81 passes through the first lens group 524b and the second lens group 524a in this order and reaches the screen 542. Light rays that exit from the center of the aperture of the projection lens 542 toward the display panel 81 are incident on the liquid crystal layer 87 substantially perpendicularly, that is, telecentric.
[0323]
For ease of explanation, it is assumed that 81a is a display panel that modulates R light, 81c is a display panel that modulates B light, and 81b is a display panel that modulates G light.
[0324]
The dichroic mirror 523 serves both as a color composition system and a color separation system. The band of the UVIR cut filter 521c is a half value of 430 nm to 690 nm. Hereinafter, when describing the optical band, it is expressed by half value. The dichroic mirror 523a reflects R light and transmits G light and B light. The G light is reflected by the dichroic mirror 523b and enters the display panel 81b. The band of R light is 600 nm to 690 nm, and the band of G light is 510 nm to 570 nm. The dichroic mirror 523b transmits B light. The B light is incident on the display panel 81c. The band of incident B light is 430 nm to 490 nm. Each display panel 81 forms an optical image as a change in the scattering state in accordance with each video signal. The optical system formed by each display panel 81 is color-synthesized by the dichroic mirror 523, enters the projection lens 524, and is enlarged and projected on the screen 542.
[0325]
As shown in FIG. 61, the display panel 81 includes reflective electrodes 372 arranged in a matrix, and modulates incident light according to a voltage application state between the reflective electrode 372 and the counter electrode 371b. The liquid crystal layer 87 on the pixel to which the voltage is applied to the reflective electrode 372 is in a transmissive state, and the pixel to which no voltage is applied is in a scattering state. When the liquid crystal layer 87 is in a transmissive state, the light incident from the counter substrate 161 is reflected by the reflective electrode 372 and is emitted from the counter substrate 161 again.
[0326]
FIG. 80 shows an apparatus that performs color separation color composition using the dichroic mirror 523, but color separation color composition can also be performed using the dichroic prism 553. FIG. 81 shows the configuration. The dichroic prism 553 has two light separation surfaces 551, and the light separation surface 551 separates white light into R, G, and B primary colors. Each display panel 81 is attached to a dichroic prism 551 through an optical coupling layer 392. Reference numeral 552 denotes an auxiliary lens.
[0327]
As shown in FIG. 82, a light absorption film (black paint) 561 is applied to the surface of the dichroic prism 551. Examples of the material are the same as the light shielding film 155 shown in FIG. The light absorption film 561 has a function of absorbing light scattered by the display panel 81.
[0328]
The display panel 81 is attached to a dichroic prism 553, and a light absorption film 561 is applied to an ineffective area (a surface on which light is not input / output) of the dichroic prism 553. This configuration is functionally similar to the transparent substrate 391 being optically coupled to the display panel 81 and a light absorption film being applied to the ineffective area of the transparent substrate 391 as shown in FIG. That is, the transparent substrate 391 may be replaced with the dichroic prism 553. For example, if the display panel 81a is considered as the center and the display panel 81a modulates R light, the incident light 81a is incident from the light incident / exit surface 562 of the dichroic prism 553, and the R light is reflected by the light separation surface 551b. Is done. The display panel 81a changes the degree of scattering of the light modulation layer 87 in accordance with the magnitude of the voltage applied to the reflective electrode 372. Among them, the transmitted light component is reflected again by the light separation surface 551b and is emitted from the light incident / exit surface 562. Most of the scattered light is incident on the light absorption film 561 and absorbed, and returns to the light modulation layer 87, so that secondary scattering is not generated.
[0329]
From the above, it can be understood that in FIG. 81, the dichroic prism 553 has a function of color separation and color synthesis and a function of preventing the generation of secondary scattered light. The configuration shown in FIG. 81 is very simple and small in color separation / synthesis system. It also has a function of preventing secondary scattering.
Note that the dichroic prism is not limited to a glass or other solid material, but includes, for example, a cubic container filled with a liquid such as ethylene glycol. Since the liquid has fluidity, it is preferable because it can cool and cool the liquid crystal panel. A dichroic mirror plate for color separation is arranged inside the container, and a black paint is applied to the outside to absorb the light scattered by the liquid crystal panel.
[0330]
The above apparatus is a projection display apparatus using a display panel that forms an optical image as a change in the light scattering state as a light valve (light modulation means). However, the technical idea of converting P-polarized light with the phase plate of the present invention, narrowing the bandwidth of light in the color separation color composition system, and improving the hue of the projection display device is to modulate other random light. The present invention is also applied to a projection display device using a display panel that performs the above-described operation.
[0331]
80 and 81 are shown two-dimensionally for easy understanding, but more specifically, they should be configured as shown in FIG. In FIG. 83, attention should be paid to the tilt direction of the dichroic mirror 532 and the tilt direction of the plane mirror 531. The dichroic mirror 532 is generally used by depositing a dielectric multilayer film on a transparent substrate and transmitting or reflecting light of a specific wavelength band. This type of dichroic mirror 532 has a characteristic that the spectral performance is shifted depending on the incident angle of the light beam, and the optical axis of the incident light beam 541a and the optical axis of the outgoing light beam 541b are incident at different angles as shown in FIG. Since the spectral characteristics for color separation and the spectral characteristics for color synthesis are different from each other, it is difficult to obtain a projected image having a desired color purity.
[0332]
In the configuration shown in FIG. 83, the plane including the optical axis 541a of the illumination light emitted from the light source 521 and the optical axis 541b of the projection light reflected by the liquid crystal display panel 81 is the center normal line of the liquid crystal display panel 81 and the dichroic mirror. Since the optical axis 541 a and the plane including the optical axis 541 b are arranged at an angle of 45 ° with the color separation / synthesis surface of the dichroic mirror 532. Therefore, both illumination light and projection light can be incident on the dichroic mirror 532 at the same incident angle of 45 °.
[0333]
The spectral transmittances of the dichroic mirrors 532a and 532b are shown in FIGS. 84 (a) and 84 (b). (a) shows the spectral transmittance when the incident angle of light on the dichroic mirror 532a is 45 °. The dichroic mirror 532a reflects R light and transmits G light and B light. (B) shows the spectral transmittance when the light incident angle on the dichroic mirror 532b is 45 °. The dichroic mirror 532b is a type that reflects B light and transmits G light.
[0334]
According to the configuration of the present embodiment, since the spectral performance in the case of color separation matches the spectral performance in the case of color synthesis, the spectral performance shown in (a) and (b) of FIG. Can be reflected.
[0335]
For comparison, a description will be given of the case of the configuration shown in FIG. If the optical axis 541a of the illumination light is configured to enter the liquid crystal display panel 81 at 5 °, the optical axis 541a of the illumination light and the optical axis 541b of the projection light form an angle of 10 °, and the dichroic mirror 523a of the illumination light The incident angle to 523b is 40 °, and the incident angle of projection light to the dichroic mirrors 523a and 523b is 50 °. The spectral transmittance when the incident angle is 40 ° and when the incident angle is 50 ° is shown in FIGS. 85 (a) and 85 (b). (a) shows the spectral transmittance of the dichroic mirror 523a, and (b) shows the spectral transmittance of the dichroic mirror 523b. In the figure, the solid line indicates the incident angle of the light beam is 40 °, and the dotted line indicates the incident angle of the light beam is 50 °. Shows the case. From FIG. 85, due to the wavelength shift depending on the incident angle, the spectral performance of the illumination light and the spectral performance of the projection light are significantly different, and it is difficult to obtain the desired color purity without reducing the light utilization efficiency. Understand.
[0336]
In order to perform color display with one liquid crystal display panel 81, the configuration shown in FIG. 86 or 87 is employed. 86 uses the display panel (display device) 81 of the present invention including the color filter 471 shown in FIGS. 57 to 60 as a light valve. When the polarizing plate 331 is used, one of the incident side 331a and the emission side 331b is disposed.
[0337]
Of course, both the incident side and emission side polarizing plates 331a and 331b may be arranged. When both polarizing plates 331a and 331b are used, it is important that the polarizing axes of the polarizing plates 331a and 331b are matched (see the arrangement of the polarizing plates 331a and 331b in FIG. 38A). In this case, the light passing through the polarizing plate 331a becomes linearly polarized light. When the liquid crystal layer 87 is in a transparent state (light transmission state), the linearly polarized light is transmitted through the liquid crystal layer 87 while maintaining the polarization state. Therefore, the output side polarizing plate 331b does not lose light, so that strong output light can be obtained. On the other hand, when the liquid crystal layer 87 is in the light scattering state, the light incident on the liquid crystal layer 87 is scattered, so that the linearly polarized state is lost. Accordingly, about half of the light is absorbed by the polarizing plate 331b on the emission side.
When the liquid crystal layer 87 is in a scattering state, the display is black. The fact that light is absorbed by the output-side polarizing plate 331b means that the light reaching the screen is reduced during black display, so that the display contrast is improved.
[0338]
From the above, in a projection display device that uses a display panel that forms an optical image as a change in the light modulation state as a light valve, the polarization axis 331a of the polarizing plate 331a on the incident side of the display panel and the polarizing plate 331b on the outgoing side. It is important to make the polarization axis substantially coincide. The reason why they substantially coincide is that even if the polarizing axis of the polarizing plate is slightly deviated, the display contrast is only slightly lowered, and there is no practical problem. Note that the deviation of the angle of the polarization axis is preferably within 20 °.
[0339]
In the above description, the polarizing plates 331 are arranged on the incident side and the emission side of the display panel. However, it should be considered that the configuration of FIG. 88 is also included. In FIG. 88, reference numeral 881 denotes a polarizing screen. As an example, when the polarizing screen 881 is “reflective”, a configuration in which a reflecting plate and a polarizing plate are bonded is applicable. For example, it is sold by Arisawa Manufacturing Co., Ltd. Further, when the polarizing screen is “transmission type”, a polarizing plate and a diffusing plate or the like to be a screen are bonded. Therefore, the polarizing screen may be transmissive or reflective. When linearly polarized light that coincides with the polarization axis of the polarizing screen 881 is incident, the linearly polarized light is reflected by the polarizing screen or transmitted through the polarizing screen. Conversely, when linearly polarized light perpendicular to the polarization axis of the polarizing screen is incident, it is absorbed by the polarizing screen.
[0340]
The display device of FIG. 88 includes a polarizing plate 331a on the incident side of the display panel, but does not have the polarizing plate 331b on the emission side. Instead, a polarizing screen 881 is arranged. The polarizing screen 881 functions as the polarizing plate 331b. The display device of FIG. 88 can also realize high contrast display as in the previous embodiment (FIG. 86). The reason and the operation of the projection display device may be considered by replacing the polarizing plate 331b and the polarizing screen 881 on the emission side in the above description, and thus the description is omitted.
[0341]
In the description of FIGS. 86 and 88, the projection display device using one display panel has been described. However, the technical idea of substantially matching the polarization axis of the incident-side polarizing plate 331a with the outgoing-side polarizing plate 331b (or the polarizing screen 881) is that a plurality of display panels such as FIG. 71, FIG. 79, and FIG. Needless to say, the present invention can also be applied to a projection display device to be used. Further, it is more preferable that the direction of the polarization axis of the polarizing plate 331 or the like is set in consideration of the direction in which the “polarization dependency” occurs, as described with reference to FIGS. 32 to 34, 36, and 37. . Further, the polarizing means is not limited to the polarizing plate 331, and a polarizing beam splitter or the like may be used.
[0342]
When the display panel is not provided with a color filter, the display panel is configured as shown in FIG. White light from the light source 521 is separated into three primary color lights of R, G, and B by three dichroic mirrors 523. On the incident side of the liquid crystal display panel 81, a microlens array 581 in which microlenses 528 corresponding to a set of three pixels 101 of R, G, and B are arranged in a matrix is arranged. A transparent member 391 is connected to the emission side of the display panel via a transparent bonding layer. The directions of the primary colors of R, G, and B are changed by the microlens and are incident on the pixels that modulate the R, G, and B lights.
[0343]
Next, a description will be given of a projection display apparatus in which the projection optical system is further improved to ensure good color reproducibility and realize high brightness display and high contrast display. A projection display device using a PD liquid crystal display panel as a light valve has an advantage that a bright projection image can be obtained. However, when a projection lens having a small effective F number is used, most of the light scattered in the black display state is caused by the projection lens. It will be condensed and black floating will occur. As a result, the contrast of the projected image decreases. When a projection lens having a large effective F number is used, high contrast is obtained, but light that cannot be collected in a white display state is generated, so that light loss occurs. In order to suppress the light loss, it is necessary to increase the effective F number of the illumination light in accordance with the effective F number of the projection lens.
[0344]
When forming illumination light having a large effective F number, that is, having good parallelism, it is difficult to obtain high light utilization efficiency due to increased light loss unless a light emitter close to a point light source is used. On the other hand, the light emitter of a metal halide lamp generally known as a short arc type has a length of about 5 to 10 mm, and the light emitter of a xenon lamp known to be close to a point light source has a length of about 2 to 4 mm. . When the light emitted from these illuminants is efficiently collected to form light that illuminates the light bulb, in any case, there is a certain irradiation angle, so the effective F number of the projection lens matches this. It is necessary to let
[0345]
In order to increase the effective F number of the illumination light without increasing the light loss, if the size of the light emitter is reduced, a general lamp has a problem because the light emission characteristics such as life characteristics are extremely deteriorated. . Although it is effective to use a light valve having a relatively large display area with respect to the light emitter, it is difficult to construct a compact projection display device, and there is a problem because the cost increases.
[0346]
Therefore, in order to construct a projection display device using a PD liquid crystal display panel with little light loss and obtain a bright and high-contrast projection image, it is necessary to match the effective F number of the illumination light with the effective F number of the projection lens. is there. Since the projection lens provides the minimum necessary opening for the light emitted from the light valve, stray light in the projection lens can be reduced, and a projected image with high contrast can be obtained.
[0347]
Further, it is preferable that the effective F number of the illumination light and the effective F number of the projection lens are matched well at every point on the display area of the light valve. In particular, when a PD liquid crystal display panel is used as the light valve, it is important to make the contrast uniform over the entire area of the projected image. For this purpose, it is necessary to favorably restrict the illumination light irradiation angle and the converging angle of the projection lens not only on the on-axis point on the light valve but also on any off-axis point. Conventionally, it has been difficult to control the effective F number of the illumination light and the effective F number of the projection lens as described above, and as a result, the image quality of the projected image is deteriorated.
[0348]
FIG. 90 is a block diagram of a projection display apparatus according to the present invention that solves the above problems. The projection display device of the present invention includes a light emitter 592 as light generating means, a light collecting means for collecting light emitted from the light emitter, a light transmitting means for receiving light emitted from the light collecting means, a light The display panel (light valve 81) of the present invention as light modulation means illuminated by light emitted from the transmission means, a projection lens 591 as projection means for projecting an optical image on the light valve 81 onto the screen, a light A first aperture stop 596 disposed on the incident side of the bulb 81 and a second aperture stop 598 disposed on the exit side of the light valve 81 are provided.
[0349]
The light transmitting means includes an input part converging lens array 594, a central part converging lens array 595, and an output part converging lens 597. The input part converging lens array 594 includes a plurality of input part converging lenses 599 arranged two-dimensionally, The central convergent lens array 597 is formed by two-dimensionally arranging a plurality of central convergent lenses 600 paired in the same number as the plurality of input convergent lenses 599.
[0350]
Each of the input part converging lenses 599 forms a plurality of secondary light emitters in the vicinity of the main plane of each of the corresponding central part converging lenses 600, and each of the central part converging lenses 600 corresponds to the output part converging lens 597. Each of the object images in the vicinity of the main plane of each of the input unit converging lenses 599 is formed in the vicinity of the effective display area of the light valve 81 as a superimposed form, and the output unit converging lens 597 emits light emitted from a plurality of secondary light emitters. The projection lens 591 is effectively reached.
[0351]
The first aperture stop 596 is disposed in the vicinity of the plurality of secondary light emitters, and the optical element interposed in the optical path from the first aperture stop 596 to the second aperture stop 598 includes the first aperture stop 596 and the second aperture stop 598. The first aperture stop 596 has an opening shape that selectively allows light passing through the effective region of the secondary light emitter to pass through, and the second aperture stop 598 is the whitest of the light valve. In the display state, it has an aperture shape that selectively allows light that has passed through the first aperture stop 596 to pass therethrough.
[0352]
Hereinafter, first, the basic configuration of the optical system of the projection display apparatus of the present invention will be described with reference to FIG. The projection display apparatus mainly includes a metal halide lamp 521a as a light generating means, a parabolic mirror 521b, a light source 521 including a UV-IR cut filter 521c, an input part converging lens array 594, a central part converging lens array 595, and an aperture 596. , An output unit converging lens 597, a liquid crystal display panel 81, a projection lens 591 as projection means, and a diaphragm 598. The projection lens 591 includes a front lens group 591a and a rear lens group 591b. The output unit converging lens 597 and the rear group lens 591b have a diaphragm 596 and a diaphragm 598 in a conjugate relationship with each other.
[0353]
The input unit converging lens array 594 includes a plurality of input unit converging lenses 599 arranged two-dimensionally. FIG. 91 shows an example of the configuration. Ten input unit converging lenses 599 having rectangular openings are arranged so as to be inscribed in a region of a perfect circle. The ten input unit converging lenses 599 are planoconvex lenses having the same aperture shape, and the ratio of the short side to the long side of the rectangular aperture is set to 4: 3. That is, the screen shape of the effective display area of the liquid crystal display panel 81 is used. If the screen shape is 16: 9, the input unit converging lens 599 is also set to 16: 9.
[0354]
The central convergent lens array 595 is configured by arranging a plurality of central convergent lenses 600 in a two-dimensional manner. The central convergent lenses 600 having the same number and the same aperture as the input convergent lenses 599 are arranged in the same manner as the input convergent lens array 594.
[0355]
An illumination procedure in the projection display apparatus will be described. The light emitted from the light emitter 592 of the metal halide lamp 521a is reflected by the parabolic mirror 521b, travels substantially parallel to the optical axis 604, and enters the input unit converging lens array 594. Since the cross-sectional shape of the light emitted from the parabolic mirror 521b is generally a perfect circle, the input unit converging lens array 594 is configured such that the sum of the apertures of the input unit converging lens 599 is inscribed therein. The light that has passed through the input unit converging lens array 594 is divided into the same number of partial light beams as the input unit converging lens 599, and each partial light beam illuminates the effective display area of the liquid crystal display panel 81.
[0356]
The light that has passed through the input unit converging lens 599 is guided to the opening of the corresponding central unit converging lens 600 and converged. Secondary light emitters, for example, 601A and 601B are formed on the respective apertures of the central converging lens 600. An example of a plurality of secondary light emitters 601 formed on the central convergent lens array 595 is schematically shown in FIG. Each of the central convergent lenses 600 effectively transmits the corresponding light onto the display area of the PD liquid crystal display panel 81. Specifically, an object on the main plane of the corresponding input unit converging lens 599, for example, a real image 603 of 601A and 601B is formed in the vicinity of the display area of the PD liquid crystal display panel 81. However, each central convergent lens 600 is appropriately decentered, and a single real image 603 is formed by superimposing a plurality of images.
[0357]
According to the above configuration, the display area of the PD liquid crystal display panel 81 and each aperture of the input unit converging lens 599 are approximately conjugate to each other. Therefore, if the aperture of the input unit converging lens 599 is made similar to the display area of the PD liquid crystal display panel 81, the light loss can be suppressed by matching the section of the illumination light with the shape of the display area. Therefore, the input part converging lens array 594 shown in FIG. 91 is preferably used in combination with a PD liquid crystal display panel 81 that displays an image with an aspect ratio of 4: 3 corresponding to NTSC.
[0358]
Note that all the configurations, shapes, technical ideas, and functions described so far are applied to the PD liquid crystal display panel in this configuration. For example, the display method of FIGS. 1 and 2, the circuit configurations of FIGS. 3 and 4, the panel configurations of FIGS. 25 to 29, FIGS. 39 to 45, FIGS. 53 to 68, 69, and 70, FIGS. 37 is a configuration and driving method related to the countermeasure for polarization dependence in FIG. 37 and the driving method in FIGS. 18 to 22. Further, the display panel is not limited to the PD liquid crystal display panel, and may be a display panel to which PLZT is applied, a TN and STN liquid crystal display panel.
[0359]
In general, light emitted from a concave mirror such as a parabolic mirror has a relatively large brightness unevenness. If light with large brightness unevenness is transmitted as it is to illuminate the PD display liquid crystal display panel 81, the uniformity of the brightness of the projected image decreases. If illumination is performed using only a region where the brightness is relatively uniform, light that cannot be used increases, so that light use efficiency decreases. On the other hand, the projection display device of the present invention has an advantage that it is possible to obtain a projection image with high light utilization efficiency and excellent brightness uniformity. The reason is described below.
[0360]
The input unit converging lens array 254 divides light with large brightness unevenness into a plurality of partial light beams. The brightness unevenness of each partial light beam on the aperture of the input part converging lens 599 is smaller than the brightness unevenness of the cross section of the light beam before splitting. Each of the central converging lenses 600 enlarges a partial light beam with less unevenness of brightness to an appropriate size and superimposes it on the display area of the PD liquid crystal display panel 204. Therefore, it is possible to realize illumination with good brightness uniformity.
[0361]
Since the sum of the apertures of the input unit converging lens 599 is inscribed in the cross section of the incident light beam, the light loss in the input unit converging lens array 594 is small. Further, since each of the apertures of the central convergent lens 600 is sufficiently large with respect to the secondary light emitter 592, there is little light loss in the central convergent lens array 595. Furthermore, since the cross section of the light incident on the PD liquid crystal display panel 81 is matched with the shape of the display area, the light loss in the PD liquid crystal display panel 81 is small. Accordingly, most of the light emitted from the light emitter 592 is reflected by the parabolic mirror 521b, and the input part converging lens array 594, the central part converging lens array 595, the output part converging lens 597, and the PD liquid crystal display panel 81 are reflected. It passes through and reaches the projection lens 591. Therefore, if light loss in the projection lens 591 is suppressed, high light utilization efficiency is realized, and a bright projected image with excellent brightness uniformity is obtained.
[0362]
By the way, since a plurality of secondary light emitters 592 are discretely formed on the central convergent lens array 600, the effective F number of the illumination light in this case is equivalent to the total area of the secondary light emitters 592. It is necessary to determine from the irradiation angle converted to. On the other hand, the condensing angle of the light emitted from the PD liquid crystal display panel 81 at the most angle with the optical axis 604 is larger than this equivalent irradiation angle. Therefore, in order to suppress light loss, it is necessary to make the effective F number of the projection lens 591 smaller than the effective effective F number of the illumination light. This is problematic in the case of the PD liquid crystal display panel 81 because it reduces the contrast of the projected image.
[0363]
On the other hand, in the projection display apparatus of the present embodiment, the apertures on the illumination light side and the projection lens side can both be made the minimum necessary size without increasing light loss by the action of the diaphragm 596 and the diaphragm 598. Therefore, it is possible to suppress a decrease in contrast. Specifically, the aperture of the diaphragm 596 on the illumination light side is shaped as shown in FIG. 92 in accordance with the effective area of the secondary light emitter 592 formed discretely. Dashed lines correspond to the respective apertures of the central convergent lens 660 of FIG. In addition, since a real image of the secondary light emitter 592 is formed on the aperture of the diaphragm 591 on the projection lens side, the aperture shape of the diaphragm 598 is also the same as the aperture shape of the diaphragm 596. Thereby, since the light that has passed through the diaphragm 596 passes through the diaphragm 598, high light utilization efficiency can be realized. At the same time, since the projection lens 591 provides the minimum necessary opening required by the illumination light, a display image with high contrast can be realized. As a result, it is possible to provide a bright and high-quality projection image quality, so that a very large effect can be obtained.
[0364]
The input part converging lens array 594, the central part converging lens array 595, the diaphragm 596, and the diaphragm 598 used in the projection display device of the present invention are preferably configured as follows. FIG. 93 shows the configuration of the central convergent lens array 595 in this case. In general, the size of the secondary light emitter 592 is larger as that formed by the input part converging lens 599 located near the optical axis. Therefore, the apertures of the central convergent lens 600 do not necessarily have to be the same, and may have a necessary and sufficient size for each of the secondary light emitters 601. If the central convergent lens array 595 is configured by aggregating and arranging a plurality of central convergent lenses 600 having different apertures effectively, there is an advantage that the sum of the aperture areas can be reduced. The input part converging lens array 594 combined with the central part converging lens array 595 is configured in the same manner as that shown in FIG. 94, and each of the input part converging lenses is appropriately decentered so that the center of the aperture of the corresponding central part converging lens 600 is obtained. The secondary light-emitting body 601 may be formed.
[0365]
In this case, an aperture-shaped stop 596 shown in FIG. 95 may be used instead of the stop 596 on the illumination light side. The same applies to the stop 598 on the projection lens side. Thereby, there is an advantage that the aperture diameter of the central convergent lens array 595 can be reduced and the lens diameter of the projection lens 591 can be reduced without causing optical loss.
[0366]
As described above, the projection display apparatus according to the present embodiment has a greater effect when a plurality of secondary light emitters are discretely formed to illuminate the light valve. Even when a projection lens having a large maximum condensing angle is used, the minimum necessary opening for light emitted from the light valve can be provided by providing a diaphragm having a plurality of discrete openings. As a result, a bright projected image with high contrast can be obtained.
[0367]
FIG. 89 shows the configuration of a projection display apparatus that can display a color image using three display panels 81 of the present invention based on FIG. The metal halide lamp 521a forms a light emitter 592 that emits light including three primary colors. The display areas of the PD liquid crystal display panels 81b and 81c are illuminated by the same procedure as that shown in FIG. However, the illumination light is decomposed into three primary color lights by the functions of the dichroic mirrors 523a and 523b and the flat mirror 531a, and guided to the corresponding display areas of the PD liquid crystal display panel 81, respectively.
[0368]
In the PD liquid crystal display panel 81, an optical image corresponding to the three primary colors is formed on each display area in accordance with a video signal supplied from the outside. The projection lens 591 includes a front lens group 591a and a rear lens group 591b, and enlarges and projects an optical image of three primary colors on a screen. The light emitted from the PD liquid crystal display panel 81 is combined with one optical path by the action of the dichroic mirrors 523c and 523d and the flat mirror 531c, so that a full-color projection image is obtained.
[0369]
The diaphragm 596 on the illumination light side and the diaphragm 598 on the projection lens side are the same as those shown in FIG. 90 or 93 and are used for the same purpose. The output unit converging lens 597 and the rear group lens 591b are appropriately configured so that the diaphragm 596 and the diaphragm 598 are in a conjugate relationship with each other. With the configuration described above, it is possible to realize a color display projection display device that does not have color reproducibility and has high luminance and high contrast display. The other points have been described with reference to FIG.
[0370]
The above projection display apparatus has been described as a front projection display apparatus in which the screen 542 and the optical block are separated, but the present invention is not limited to this. For example, as shown in FIG. 72, a rear projection display apparatus in which a screen 542 and an optical block 702 are integrated in a cabinet may be used. Needless to say, FIG. 71, FIG. 79, FIG. 80, and the like correspond to the optical block. The light output from the optical block is reflected by mirrors 531 a and 531 b and projected onto the screen 542.
[0371]
The video signal display method of the present invention and a display device (display panel) using the video signal display method can be applied to a viewfinder used as a playback image display device such as a video camera. The viewfinder means a light source, a liquid crystal display panel, and a lens for enlarging an image of the liquid crystal display panel. The viewfinder for a video camera described below and a head mounted display This corresponds to the configuration of the image display unit. FIG. 96 is an external view of the viewfinder of the present invention. Reference numeral 668 denotes an eyepiece cover, and 669 denotes a mounting bracket for the video camera. Reference numeral 667 denotes a body, and a lens 663, a display panel 81, and the like are stored in the body 667.
[0372]
FIG. 97 shows the internal structure of the body 667 shown in FIG. Reference numeral 661 denotes a light emitting element, 663 denotes a condenser lens, and 666 denotes a magnifying lens. As an example, the diagonal length of the display area of the display panel 81 is 28 mm, and the condenser lens 663 has an effective diameter of 30 mm and a focal length of 15 mm. A light emitting element 661 is disposed in the vicinity of the focal point of the condenser lens 663. The condenser lens 663 is a plano-convex lens, and the plane is directed to the light emitting element 661 side. An eyepiece ring 665 is attached to the end of the body 667. A magnifying lens 666 is attached to the eyepiece ring 665. The inner surface of the body 667 is black or dark for absorbing unnecessary light.
[0373]
Reference numeral 662 denotes a light shielding plate having a circular hole in the center. The light emitting element 661 has a function of reducing a region where light is emitted from the light emitting element 661. When the hole area increases, the display image on the display panel 81 becomes brighter, but the contrast decreases. This is because the amount of light incident on 663 by the condenser lens increases, but the directivity of the incident light deteriorates. When the diagonal length of the display area of the display panel as described above is 28 mm, the area that emits light should be 15 mm 2 or less. This corresponds to the diameter of a pinhole having a diameter of about 4 mm or more. Preferably, it should be 10 mm 2 or less. However, if the diameter of the hole is made too small, the directivity of light becomes unnecessarily narrow, and when the viewfinder is viewed, the display screen becomes extremely dark just by slightly shifting the viewpoint. Therefore, the area of the hole should be at least 2 mm2. As an example, when the hole diameter is a straight line of 3 mm, the brightness of a display screen equivalent to that of a viewfinder using a conventional surface light source can be obtained, and the contrast at that time is also good. The region that emits light, that is, the hole diameter should be considered to be in the range of 0.5 mm to 5 mm in diameter. However, this is a case where the diagonal length of the display screen is 28 mm. As the diagonal length increases, the optimum hole diameter also changes according to the diagonal length.
[0374]
Light emitted from the light emitting element 661 to a wide solid angle is converted into light that is close to parallel and has low directivity by the condenser lens 663, and enters from the counter electrode 88 side of the display panel 81. The observer sees the display image on the display panel 81 with his eyes in close contact with the eyepiece rubber 688. That is, the position of the observer's pupil is substantially fixed. When it is assumed that all pixels of the display panel 81 travel light straight, the condenser lens 663 is radiated from the light emitting element 661, and after the light incident on the effective area of the condenser lens 663 passes through the magnifying lens 666, All are incident on the pupil of the observer. Since the lens 666 functions as a magnifying lens, the observer can enlarge and view a small display image on the display panel 81.
[0375]
Since the position of the observer's pupil is substantially fixed by the eyepiece cover 668 in the viewfinder, the light source disposed behind the viewfinder may have a narrow directivity. In a conventional viewfinder that uses a light box using a fluorescent tube as a light source, only light that travels within a small solid angle in a certain direction from an area that is almost the same size as the display area of the display panel is used, and proceeds in another direction. Light is not used. That is, the light utilization efficiency is very poor.
[0376]
In the present invention, a light source having a small illuminant is used, and light emitted from the illuminant to a wide solid angle is converted into light almost parallel by the condenser lens 663. As a result, the directivity of the light emitted from the condenser lens 663 is narrowed. If the observer's viewpoint is fixed, the light having the narrow directivity described above is sufficient for the use of the viewfinder.
[0377]
Naturally, if the size of the light emitter is small, the power consumption is small. As described above, the viewfinder of the present invention utilizes the fact that the observer views the display image with the viewpoint fixed. A normal direct-view liquid crystal display device requires a certain viewing angle, but a viewfinder is sufficient for use if a display image can be satisfactorily observed from a predetermined direction. When the condenser lens 663 has no aberration and the transmittance is 100%, the luminance of the light emitter viewed through the condenser lens 663 is equal to the luminance of the light emitter itself. Assuming that the maximum transmittance of the display panel including the color filter, polarizing plate, image aperture ratio, etc. is 3%, the transmittance of the condenser lens 163 is 90%, and the brightness necessary for the viewfinder is 15 ft-L, the light source The required brightness is about 560 ft-L. Light emitting elements that satisfy these requirements include light emitting tubes such as cathode ray tubes and fluorescent tubes, fluorescent light emitting elements, xenon lamps, halogen lamps, tungsten lamps, metal halide lamps, LEDs, electroluminescence (EL), and other electronic devices. Examples thereof include a device that emits light by an operation, a device that emits light by discharge such as plasma or a display panel (PDP), and the like that emits light. Any of these light emitting elements may be used as the light generating means, but among them, a light emitting tube, an LED, and a fluorescent light emitting element are optimal in terms of low power consumption, small size, and white light emission. Among them, the Luna Pastel 07 series (7 mm diameter arc tube) of Mini Pyro Electric Co., Ltd. is optimal because of its low power consumption.
[0378]
In the display panel 81, when the voltage applied to each pixel is changed, the light scattering degree of the pixel changes. The light scattering degree is greatest when no voltage is applied, and the light scattering degree decreases when the applied voltage is increased. When light having narrow directivity is incident on the display panel 81 and the degree of light scattering is changed, the amount of light incident on the observer's pupil from that pixel changes. That is, since the luminance of the pixel as viewed from the observer changes, image display is performed using this.
[0379]
A mosaic color filter (not shown) is attached to the display panel 81. The pixel arrangement is a delta arrangement, and the number of pixels is about 100,000 pixels. The color filter 471 transmits any one of red, green, and blue. You may control the film thickness of each color with the structure of a color filter. The film thickness of the color filter is adjusted when forming the color filter. That is, the thickness of the color filter is changed between red, green, and blue. The film thickness of the liquid crystal on each pixel can be adjusted according to the color filter color depending on the film thickness of the color filter. In particular, PD liquid crystal display panels have poor scattering characteristics for long-wavelength light (red light). Therefore, if the liquid crystal layer thickness of the red pixel is made thicker than other blue and green pixels, the scattering characteristics can be improved, and the gradation of red, green and blue can be made uniform. . That is, the display panel 81 of the present invention having the configuration shown in FIGS. 57 to 60 may be used.
[0380]
A part of the light emitted from the display panel 81 enters the pupil of the observer, but the other light becomes stray light, which causes a reduction in the contrast of the display image. In order to avoid this problem, the inner surfaces of the body 667 and the eyepiece ring 665 are black or dark in order to prevent light reflection.
[0381]
The condenser lens 663 has a flat surface, that is, a surface having a large curvature radius, facing the light emitter 661. This is because the sine condition is easily satisfied and the luminance uniformity of the display image on the display panel 81 is improved. However, it goes without saying that the condenser lens 663 is not limited to the above-described plano-convex lens, and may be a normal positive lens.
[0382]
By adjusting the degree of insertion of the eyepiece ring 665 into the body 667, focus adjustment can be performed in accordance with the visual acuity of the observer. Since the position of the observer's eye is fixed by the eyepiece cover 668, the viewpoint position is hardly shifted during use of the viewfinder. If the viewpoint is fixed, the observer can see a good image even if the directivity of light to the display panel 81 is narrow. In order to make it look better, the radiation direction of light from the light emitting element 661 may be moved in an optimum direction. Therefore, it is preferable that a position adjustment mechanism is added to the light emitting element 661 so that the light emitting element 661 can be moved slightly back and forth or left and right.
[0383]
As described above, the viewfinder of the present invention efficiently collects the light emitted from the small light emitter of the light emitting element 661 to a wide solid angle by the condenser lens 663, and therefore the back of the surface light source using the fluorescent tube. Compared with the case of using a light, the power consumption of the light source can be greatly reduced.
[0384]
In FIGS. 96 and 97, the display panel 81 is described as a PD liquid crystal display panel from the viewpoint of facilitating the description, but the present invention is not limited to this. A light scattering modulation (DSM) liquid crystal or the like that modulates light by scattering and transmission may be used. It is also known that ferroelectric liquid crystals cause scattering when the film thickness is relatively thick. Therefore, a ferroelectric liquid crystal may be used. In addition, PLZT is known to form an optical image (perform light modulation) as a change in the light scattering state. The display panel of the present invention and the display device using the display panel include these. In addition, since a display panel to which the video signal display method of the present invention is applied, a TN liquid crystal display panel may be used.
[0385]
98 to 100 show an example of a configuration using a polarizing plate. FIG. 98 shows an example in which a polarizing plate 331 is disposed on the incident / exit surface of the PD liquid crystal display panel. Of course, it may be considered simply as a TN liquid crystal display panel. This is because the technical idea in the configuration of FIG. 98 is unknown and has novelty and inventive step.
[0386]
FIG. 99 shows a configuration in which a polarizing plate 331 a on the incident side 663 of the display panel is attached to the condenser lens 663. The condenser lens 663 is made rotatable. That is, by rotating the condenser lens 663, the angle of the polarization axis 332 between the incident-side polarizing plate 331a and the outgoing-side polarizing plate 331b can be adjusted. The angular deviation of the polarization axis directly affects the display contrast. Therefore, the angle adjustment of the polarization axis is important. Preferably, as shown in FIG. 100, the convex surface of the condenser lens 663 should be directed to the light emitting element 661 side. Although the sine condition is a little worse, there is no problem in practical use. Parallel light is incident on the polarizing plate 331a. Therefore, the display contrast is higher than in the case of FIG.
[0387]
The above matters are described in detail in JP-A-7-92443. The matters described in the above publication are applied or inserted in this specification as they are. The publication describes various configurations. For example, a configuration including the diaphragm 31 in FIG. 3, a configuration in which the body 667 in FIG. 11 is bent, and a configuration using the Fresnel lens 101 in FIG.
[0388]
【The invention's effect】
According to the liquid crystal display device of the present invention, since one frame of video information is displayed in a plurality of frame periods, the input progressive scanning video signal is displayed at a lower speed than when it is displayed as it is. Can do. As a result, even when a wide-band (high-speed data rate) progressive scanning video signal such as a personal computer or workstation is displayed on a display that is not good at high-speed scanning such as a matrix type liquid crystal display, image quality does not deteriorate. That is, the display need not be divided and driven as in the conventional example, or the number of shift registers in the source driving circuit can be greatly reduced. In addition, the occurrence of a luminance difference can be prevented and power consumption can be reduced.
[0389]
Further, in the display panel of the present invention, by adopting the H inversion driving as shown in FIG. 12 or the column inversion driving as shown in FIG. 14, the generation direction of the lateral electric field can be defined and the occurrence of flicker can be prevented. . Further, in the projection display device of the present invention, by adopting the driving method described with reference to FIGS. 16 to 17, it is possible to sufficiently prevent flicker and realize a good image display.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a video signal display method according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a video signal display method according to another embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of a video signal display device according to an embodiment of the present invention using an active matrix type liquid crystal display panel.
4 is a block diagram showing a more detailed configuration of the gate drive IC in FIG. 3;
5 is a timing chart of memory control signals input to the line memory in FIG. 3 and input / output image signals thereof.
6 is a timing chart of gate drive IC control signals input to the gate drive ICs 38 and 39 from the gate drive IC control circuit 36 in FIG. 3;
7 is a timing chart of gate drive IC control signals input to the gate drive ICs 38 and 39 from the gate drive IC control circuit 37 in FIG.
FIG. 8 is an explanatory diagram of a driving method according to the present invention.
FIG. 9 is an explanatory diagram of a video signal processing apparatus according to the present invention.
FIG. 10 is an explanatory diagram of a display device of the present invention.
FIG. 11 is a block diagram showing a configuration of a video signal display device according to an embodiment of the present invention using an active matrix type liquid crystal display panel.
FIG. 12 is an explanatory diagram of a video signal display method according to the present invention.
FIG. 13 is an explanatory diagram of a video signal display method according to the present invention.
FIG. 14 is an explanatory diagram of a video signal display method according to the present invention.
FIG. 15 is an explanatory diagram of a video signal display method according to the present invention.
FIG. 16 is a block diagram of a display device of the present invention.
FIG. 17 is a block diagram of a display device of the present invention.
FIG. 18 is an explanatory diagram of a video signal display method according to another embodiment of the present invention.
FIG. 19 is an explanatory diagram of a video signal display method according to another embodiment of the present invention.
FIG. 20 is an explanatory diagram of a video signal display method according to another embodiment of the present invention.
FIG. 21 is an explanatory diagram of a video signal display method according to another embodiment of the present invention.
FIG. 22 is an explanatory diagram of a video signal display method according to another embodiment of the present invention.
FIG. 23 is an explanatory diagram of the operation of a polymer dispersed liquid crystal.
FIG. 24 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 25 is a plan view of a display device according to another embodiment of the present invention.
FIG. 26 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 27 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 28 is a partial equivalent circuit diagram of a display device according to another embodiment of the present invention.
FIG. 29 is an explanatory diagram of a display device according to another embodiment of the present invention.
FIG. 30 is an explanatory diagram of P-polarized light and S-polarized light.
FIG. 31 is an explanatory diagram of P-polarized light and S-polarized light.
FIG. 32 is an explanatory diagram of a display device of the present invention.
FIG. 33 is an explanatory diagram of a display device of the present invention.
34 is an explanatory diagram of a driving method of a display device of the present invention. FIG.
FIG 35 is an explanatory diagram of a display device of the invention.
36 is an explanatory diagram of a display device of the present invention. FIG.
FIG. 37 is an explanatory diagram of a display device of the present invention.
FIG. 38 is a configuration diagram of a display device according to another embodiment of the present invention.
FIG. 39 is a sectional view of a display device according to another embodiment of the present invention.
FIG. 40 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 41 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 42 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 43 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 44 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 45 is a plan view of a display device according to another embodiment of the present invention.
FIG. 46 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 47 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 48 is an explanatory diagram of a video signal processing system according to the present invention.
FIG. 49 is an equivalent circuit diagram of the previous gate type structure.
FIG. 50 is an explanatory diagram of a video signal processing method according to the present invention.
FIG. 51 is an equivalent circuit diagram of a common electrode type structure.
52 is an explanatory diagram of a display device of the invention. FIG.
FIG. 53 is a sectional view of a display device according to another embodiment of the present invention.
FIG. 54 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 55 is a partial plan view of a display device according to another embodiment of the present invention.
FIG. 56 is a cross-sectional view of the switching element portion of the display device of the present invention.
FIG. 57 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 58 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 59 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 60 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 61 is a cross-sectional view of a display device according to another embodiment of the present invention.
62 is an explanatory diagram of a driving method of a display device of the present invention. FIG.
FIG. 63 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 64 is an explanatory diagram of a display device according to another embodiment of the present invention.
FIG. 65 is a cross-sectional view of a display device according to another embodiment of the present invention.
66 is an explanatory diagram of a display device of the present invention. FIG.
FIG. 67 is a sectional view of another embodiment of the present invention.
FIG. 68 is a sectional view of another embodiment of the present invention.
FIG. 69 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 70 is a cross-sectional view of a display device according to another embodiment of the present invention.
FIG. 71 is a block diagram of a projection display apparatus according to the present invention.
FIG. 72 is a block diagram of a projection display apparatus in another embodiment of the present invention.
FIG. 73 is an explanatory diagram of a driving method of the present invention.
FIG. 74 is a graph of VT characteristics.
75 is an explanatory diagram of a display state of a liquid crystal display panel. FIG.
FIG. 76 is an explanatory diagram of a drive circuit according to the present invention.
FIG. 77 is an explanatory diagram of the driving method of the present invention.
FIG. 78 is an explanatory diagram of the driving method of the present invention.
FIG. 79 is a block diagram of a projection display apparatus according to another embodiment of the present invention.
FIG. 80 is a configuration diagram of a projection display apparatus according to another embodiment of the present invention.
FIG. 81 is a configuration diagram of a projection display apparatus according to another embodiment of the present invention.
FIG. 82 is a perspective view of optical components of the projection display apparatus of the present invention.
FIG. 83 is an explanatory diagram of a method for improving the projection display apparatus of the present invention.
84 is a spectral characteristic diagram of reflecting the dichroic mirror of the projection display apparatus of the present invention shown in FIG. 83.
FIG. 85 is a spectral characteristic diagram of reflecting the dichroic mirror of the projection display apparatus of FIG.
FIG. 86 is an explanatory diagram of a projection display apparatus (when a color image is displayed on one display panel) in another embodiment of the present invention.
FIG. 87 is a configuration diagram of a projection display apparatus (when a color image is displayed on one display panel) in another embodiment of the present invention.
FIG. 88 is a block diagram of the projection display device of the present invention.
89 is a configuration diagram when a color image is displayed using the configuration of FIG. 90.
FIG. 90 is an explanatory diagram of a projection display apparatus according to another embodiment of the present invention.
91 is an explanatory diagram of FIG. 90. FIG.
FIG. 92 is an explanatory diagram of FIG. 90.
FIG. 93 is an explanatory diagram of FIG. 90.
FIG. 94 is an explanatory diagram of FIG. 90.
95 is an explanatory diagram of FIG. 90. FIG.
FIG. 96 is an external view of a viewfinder according to the present invention.
FIG. 97 is a sectional view of the viewfinder of the present invention.
FIG. 98 is a cross-sectional view of another embodiment of the viewfinder of the present invention.
FIG. 99 is a sectional view of another embodiment of the viewfinder of the present invention.
FIG. 100 is a sectional view of another embodiment of the viewfinder of the present invention.
FIG. 101 is a block diagram showing a configuration of a conventional video signal display device using an active matrix type liquid crystal display panel.
FIG. 102 is an explanatory diagram of problems of a conventional display device
103 is an explanatory diagram of a problem of a conventional display device. FIG.
104 is an explanatory diagram of a problem of a conventional liquid crystal display device. FIG.
FIG. 105 is an explanatory diagram of a problem of a conventional liquid crystal display device
[Explanation of symbols]
31 Display line selection circuit
32 Source signal processing circuit
33 Source drive circuit
35 Display method selection circuit
36, 37 Gate drive circuit control circuit
38 Gate drive circuit
40 A / D converter
41 line memory
42 D / A converter
43 Line memory control circuit
44 selector
81 LCD panel
86 TFT
87 Liquid crystal layer
88 Counter electrode
101 pixels
141 amplifier
142 Phase division circuit
143 Output switching circuit
144 Drive control circuit
151 Pixel electrode
153 Gate signal line
154 Source signal line
155 Light-shielding film
161 Counter substrate
162 Array substrate
163 Insulating film
171 Additional capacitor
181 Water droplet liquid crystal
182 polymer
231 Low dielectric film
232 Insulating film
263 Electric field lines
281 Liquid crystal molecules
311 Incident light
312 Normal
313 Vibration direction
315 P polarization axis
316 Light separation surface
317 P-polarized light
318 P polarization plane
319 Polarization axis of polarizing plate
331 Polarizing plate
332 Polarization axis
361 deflection beam splitter
372 Reflective electrode
373 connections
374 Insulating film
391 Transparent substrate
392 optical coupling layer
411 Convex
471 color filter
472 Dielectric thin film (UV absorbing film)
521 Light source
521a lamp
521b Concave mirror
521c UVIR cut filter
522 Relay lens
523 Dichroic Mirror
524 projection lens
526 aperture
531 Mirror
532 field lens
541 Optical axis
541a Incident ray (optical axis of incident ray)
541b Outgoing ray (optical axis of outgoing ray)
542 screen
551 Light separation surface
552 Auxiliary lens
553 Dichroic Prism
561 Light Absorption Film
562 Light entrance / exit surface
581 Micro lens array
582 Microlens
592 Luminescent body
594 Input unit convergence lens array
595 Central Converging Lens Array
596,598 aperture
597 Output unit convergence lens array
599 Converging lens for input section
600 Center convergent lens
601 Secondary light emitter
603 Real image
604 optical axis
663 condenser lens
665 eyepiece ring
666 eyepiece
667 body
668 Eyepiece rubber
669 mounting bracket
702 Reverse domain region

Claims (6)

A plurality of pixels arranged in a matrix;
A counter electrode facing the plurality of pixels;
A switching element connected to each pixel ;
A source signal line connected to the switching elements of the plurality of pixels arranged in a line direction of the matrix, and transmitting a video signal to the pixels connected to the switching elements ;
A gate signal line connected to the switching elements of the plurality of pixels arranged in a direction orthogonal to the line direction of the matrix, and controlling the pixels connected to the switching elements;
A source driving circuit for applying a video signal to the source signal line;
The gate signal line; and a gate drive circuit for applying a gate drive signal to the source driver circuit, a case of changing the polarity with respect to the potential of the counter electrode of the voltage held by the pixel, and when the polarity is the same in, for the same input video signal, when changing the polarity, as compared with the case where the polarity is the same, the liquid crystal display device, characterized by increasing the size of the video signal to be output. A first gate drive circuit;
A second gate driving circuit;
The first gate signal line for controlling the odd-numbered pixel row is connected to the first gate driving circuit,
2. The liquid crystal display device according to claim 1, wherein a second gate signal line for controlling the even-numbered pixel row is connected to the second gate driving circuit.   The liquid crystal display device according to claim 1, wherein an image display position can be moved within the display area. The source driving circuit includes the first source driving circuit and the second source driving circuit,
A first source signal line for applying a video signal to the odd pixel columns is connected to the first source driving circuit;
4. The liquid crystal display device according to claim 1, wherein a second source signal line for applying a video signal to an even-numbered pixel row is connected to the second source driving circuit. 5. . 5. The liquid crystal display device according to claim 1, wherein a phase difference film or a phase difference plate is disposed or formed on a light incident side or a light emission side to the liquid crystal layer. Light generating means;
The liquid crystal display device according to any one of claims 1 to 5, which modulates light emitted by the light generating means;
A projection display device, comprising: a projection lens that projects light modulated by the liquid crystal display device.

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