JP3211256B2 - Liquid crystal display device and liquid crystal projection television using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a projection type television (hereinafter referred to as a liquid crystal projection type television) for enlarging and projecting an image displayed on a small liquid crystal panel onto a screen, and mainly to this liquid crystal projection type television. LCD for TV
It relates to a display device.

[0002]

2. Description of the Related Art Since liquid crystal display devices have many features such as light weight and thinness, research and development have been active. However, there are many problems such as difficulty in increasing the screen. So in recent years,
Liquid crystal projection televisions that obtain a large-screen display image by enlarging and projecting a display image on a small liquid crystal panel with a projection lens or the like are attracting attention. Currently, commercially available liquid crystal projection televisions use tools that utilize the optical rotation characteristics of liquid crystals.
An istone nematic (hereinafter, referred to as TN) liquid crystal display device is used.

First, a general liquid crystal panel will be described. FIG. 29 is a plan view of the liquid crystal panel. (Figure 2
In 9), reference numeral 221 denotes a glass substrate (hereinafter, referred to as an array substrate) on which a thin film transistor (hereinafter, referred to as a TFT) as a switching element is formed, and 222 denotes an IT substrate.
A substrate on which a transparent electrode made of O or the like is formed (hereinafter, referred to as a counter substrate). A drive IC (hereinafter referred to as a source drive IC) 202 for applying a data signal to a source signal line on the array substrate 221; a polarizing plate film 223;
4 is a sealing resin.

FIG. 30 is a diagram for explaining the operation of a TN liquid crystal panel. In FIG. 30, 231 a and 231 b are polarizing plates, 232 is a polarization direction, 233 is a transparent electrode (hereinafter, I
234 is a liquid crystal molecule, 235 is a signal source, 2
36 is a switch. As shown in FIG. 30, the incident polarized light rotates 90 degrees in the off state, and transmits without rotating in the on state. Therefore, the two polarizing plates 231a, 231
If the polarization directions of 31b are orthogonal, light is transmitted in the off state and is blocked in the on state. Each other, however the polarization direction
If it is parallel to, the opposite is true. As described above, the TN liquid crystal panel modulates light to display an image.

Hereinafter, a conventional liquid crystal display device will be described. FIG. 28 is a block diagram of a conventional liquid crystal display device. In FIG. 28, reference numeral 211 denotes an amplifier for amplifying a video signal; 212, a phase division circuit for generating positive and negative video signals; 213, an output switching circuit for outputting an AC video signal having a polarity inverted for each field; 207
Denotes a liquid crystal panel, and 214 denotes a drive control circuit for synchronizing and controlling the source drive IC 202 and the gate drive IC 203.

Hereinafter, the operation of the conventional liquid crystal display device will be described. First, the gain of the video signal is adjusted by the amplifier 211 so that the video output amplitude corresponds to the electro-optical characteristics of the liquid crystal. Next, the gain-adjusted video signal enters the phase division circuit 212 to generate two video signals of positive polarity and negative polarity. These two video signals enter the output switching circuit 213, and output a video signal whose polarity is inverted for each field. The reason for inverting the polarity of the signal for each field is to prevent the liquid crystal from deteriorating by applying an AC voltage. Next, the video signal from the output switching circuit 213 is
In response to a control signal from the drive control circuit 214 , the source drive IC 202 performs processing such as level shift and sample hold of the video signal, and synchronizes with the gate drive IC 203 to make the liquid crystal panel 20
A predetermined voltage is applied to the source signal line 7.

FIG. 27 is an explanatory diagram for explaining a conventional liquid crystal display device in more detail. In FIG. 27, 201 is an X control circuit, and 203a, 203b, 203
c is a gate drive IC, 204, 205, and 206 are components of one pixel of a liquid crystal panel.
Liquid crystal as an additional capacitor and a display pixel. (FIG. 2
7) is a diagram in which the drive control circuit 214, the gate drive IC 203, the source drive IC 202, and a part of the liquid crystal panel 207 of FIG. 28 are extracted.

FIG. 31 is a timing chart for explaining the operation of the conventional liquid crystal display device. The X control circuit 201 outputs a start pulse to the start pulse signal line ST1 of the gate drive IC 203a. The gate drive IC 203a takes in the start pulse into the internal shift register circuit at the rising edge of the clock applied to the clock signal line. A voltage (hereinafter, referred to as an ON voltage) for turning on the TFT is output to the gate signal line of the liquid crystal panel 207 corresponding to the data position taken into the shift register. That is, on-voltage is outputted to gate signal lines G ₁ in the first clock. The output position of the ON voltage is sequentially shifted by a clock. Therefore, as shown in FIG. 31, the on-voltage output position is shifted to the gate signal lines G ₂ , G ₃ , G ₄ ... In synchronization with the clock. Note that a voltage (hereinafter, referred to as an off-state voltage) for turning off the TFT is output from another output signal line to which the on-state voltage is not output. Source drive IC 202
Outputs a video signal in synchronization with the aforementioned clock,
It writes the video signal to the pixels of the on-voltage position Murrell. In addition,
In this specification, the direction of a gate signal line is called a row direction, and the direction of a source signal line is called a column direction.

Hereinafter, a conventional liquid will be described with reference to FIG.
The driving method of the crystal display device will be described. FIG. 32 is an explanatory view of a driving method of a conventional liquid crystal display device . (FIG. 3
In 2), the pixels driven by the TFTs connected to the gate signal lines Gm (m is an integer) are Xm rows, and the source signal lines Sn
A pixel driven by a TFT connected to the LCD (where n is an integer) is called a Yn column. As mentioned in the previous method for driving a liquid crystal display device, signals X ₁ line is output the video signal from the source driver IC in synchronization when the on voltage is applied to that the gate signal line G ₁ a _i (where i = 1 to n) are written. Then Similarly signals in _two rows X output video signal from the source driver IC in synchronization with a turn-on voltage is applied to the gate signal line G ₂ b _i is write Murrell. The above processing is sequentially repeated, and a display image of one screen is completed.

[0010] A television image is displayed on one screen in one frame. One frame has two fields. Normally, the first field and the second field each have 24
There is a video signal corresponding to zero scanning lines or rows. A period in which one row is written in a field is called one horizontal scanning period, and a period in which one field is written is called one vertical scanning period. FIG. 32 shows a driving method when the liquid crystal panel has only 240 or less gate signal lines. That display image data is written from the first and second fields are likewise X ₁ line.

Hereinafter, a conventional liquid crystal projection television will be described with reference to the drawings. FIG. 33 is a configuration diagram of a conventional liquid crystal projection television. In FIG. 33, 26
1 is a condensing optical system, 262 is an infrared cut mirror for transmitting infrared light, 263a is a blue light reflecting dichroic mirror (hereinafter, referred to as BDM), 263b is a green light reflecting dichroic mirror (hereinafter, GDM), and 263c is red. Light reflecting dichroic mirror (hereinafter referred to as RDM) 264a, 264b, 264c, 266a, 26
6b, 266c are polarizing plates, 265a, 265b, 265
c is a transmissive TN liquid crystal display device, 267a, 267b,
267c is a projection lens system. Note that components unnecessary for the description, such as a field lens, are omitted from the drawings.

The operation of the conventional liquid crystal projection television will be described below with reference to FIG. First, blue light (hereinafter, referred to as B light) of white light emitted from the condensing optical system 261 is reflected by the BDM 263a, and this B light is incident on the polarizing plate 264a. Similarly, the light transmitted through the BDM 263a reflects green light (hereinafter referred to as G light) by the GDM 263b, and is reflected by the polarizing plate 264b.
The red light (hereinafter, referred to as R light) is reflected by 3c and is incident on the polarizing plate 264c. The polarizing plate transmits only one of the longitudinal wave component and the transverse wave component of each color light, and irradiates each liquid crystal display device with the polarization direction of the light aligned. At this time, 5
Light of 0% or more is absorbed by the polarizing plate, and the brightness of transmitted light is reduced to half or less at the maximum.

Each liquid crystal display device modulates the transmitted light by a video signal. The modulated light passes through the polarizing plates 266a, 266b, 266c according to the degree of modulation, enters the projection lens systems 267a, 267b, 267c, and is enlarged and projected on a screen (not shown) by the lens systems. .

[0014]

As is apparent from the above description, in a liquid crystal display device using a TN liquid crystal, it is necessary to make the above-mentioned liquid crystal enter linearly polarized light. I
Therefore, it is necessary to arrange polarizing plates before and after the liquid crystal display device. The polarizing plate theoretically absorbs 50% or more of the light. Therefore, as a first problem, there is a problem that only a low-luminance screen can be obtained when the image is enlarged and projected on a screen. In order to solve this problem, there is a method using a polymer-dispersed liquid crystal instead of a TN liquid crystal. A liquid crystal panel using a polymer-dispersed liquid crystal does not use a polarizing plate, so that the light use efficiency can be extremely increased. In addition, the liquid crystal display device is a CRT.
To display images as a set of line displays with an electron gun
There is also a problem that the display method is fundamentally different from spray.
You. In a liquid crystal display device, an image is displayed for one field period.
Holds the voltage written to the element. For this reason, the video display
Doing so causes a problem that the outline of the displayed image will be blurred
I do.

The polymer-dispersed liquid crystal will be briefly described below. Polymer-dispersed liquid crystals are roughly classified into two types depending on the dispersion state of the liquid crystal and the polymer. One is a type in which a liquid crystal in the form of water droplets is dispersed in a polymer. The liquid crystal exists in a discontinuous state in the polymer. Hereinafter, such a liquid crystal is referred to as PDLC, and a liquid crystal panel using the liquid crystal is referred to as a PD liquid crystal display device. The other type adopts a structure in which a polymer network is stretched around a liquid crystal layer. It looks just like a sponge with liquid crystal. Liquid crystals exist continuously without being in the form of water droplets. Hereinafter, such a liquid crystal is referred to as PNLC.
The liquid crystal display device using the liquid crystal is called a PN liquid crystal display device. In order to display an image on the two types of liquid crystal display devices, scattering and transmission of light are controlled.

[0016] PDLC utilizes the property that the refractive index varies in the direction in which the liquid crystal is oriented. In the state where no voltage is applied, the respective liquid crystal droplets are oriented 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. Here, when a voltage is applied, the alignment directions of the liquid crystals are aligned. If the refractive index when the liquid crystal is aligned in a certain direction is adjusted in advance to the refractive index of the polymer, incident light is transmitted without being scattered.

On the other hand, PNLC uses the irregularity of the alignment of liquid crystal molecules. In an irregular orientation state, that is, in a state where no voltage is applied, incident light is scattered.
On the other hand, when a voltage is applied to make the arrangement state regular, light is transmitted. The above description of the movement of the liquid crystal of PDLC and PNLC is based on a model-based concept. Although the present invention is not limited to one of the PD liquid crystal display device and the PN liquid crystal display device, the PD liquid crystal display device will be described as an example for ease of explanation. Also, PDL
C and PNLC are collectively called polymer dispersed liquid crystal.
The D liquid crystal display and the PN liquid crystal display are collectively called a polymer dispersed liquid crystal display. Further, liquids containing liquid crystal to be injected into the polymer dispersed liquid crystal display device are collectively referred to as a liquid crystal solution or a resin, and a state in which the resin component in the liquid crystal solution is polymerized and cured is referred to as a polymer.

Operation of polymer dispersed liquid crystal (FIG. 3)
This will be briefly described using (a) and (b)). (FIG. 3 (a)
(B) is an explanatory view of the operation of the polymer dispersed liquid crystal panel. 3 (a) and 3 (b), reference numeral 31 denotes an array substrate, 32 denotes a pixel electrode, 33 denotes a counter electrode, 34 denotes a liquid crystal in a droplet form, 35 denotes a polymer, and 36 denotes a counter substrate. A TFT or the like is connected to the pixel electrode 32, and a voltage is applied to the pixel electrode when the TFT is turned on and off, and the direction of liquid crystal alignment on the pixel electrode is changed to modulate light. As shown in FIG. 3A, when no voltage is applied, the liquid crystal droplets 34 are oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer 35 and the liquid crystal, and the incident light is scattered. Here, as shown in FIG. 3B, when a voltage is applied to the pixel electrode, the directions of the liquid crystals are aligned. If the refractive index when the liquid crystal is oriented in a certain direction is adjusted in advance to the refractive index of the polymer, the incident light is emitted from the array substrate 31 without being scattered.

As described above, since the polymer-dispersed liquid crystal panel does not use a polarizing plate, the light use efficiency is high, and a display image with extremely high luminance can be obtained. However, there are the following problems when trying to use the liquid crystal panel in a liquid crystal display device. It is the hysteresis property of polymer dispersed liquid crystal. The hysteresis characteristics are shown in FIG. As shown in FIG. 4, in the polymer dispersed liquid crystal, the curve of the applied voltage versus the transmittance when the absolute value of the applied voltage was gradually increased was the same as that when the absolute value of the applied voltage was gradually decreased. Not a trail. That is, it has a hysteresis characteristic. Therefore, the applied voltage V ₁ to V ₀
Transmittance when changing to is a T _2, the transmittance when changing from the applied voltage V ₂ to V ₀ becomes T _1. This phenomenon greatly hinders the gradation display of the display image.

As described above, when the polymer-dispersed liquid crystal is used, the light utilization factor is increased and a display image with high luminance can be obtained. However, desired good gradation display cannot be performed due to the hysteresis characteristic. For this reason, conventionally, it has been difficult to configure a high-quality liquid crystal display device and a liquid crystal projection television using a polymer-dispersed liquid crystal.

[0021]

When a TN liquid crystal is used, 50% or more of the light is absorbed by a polarizing plate, so that the light use efficiency is low, a high-luminance image cannot be displayed, and a large-screen display image cannot be displayed. There is a problem that it cannot be obtained. Therefore, in the present invention, a polymer dispersed liquid crystal is used. In this case, the polymer-dispersed liquid crystal is used without being affected by the hysteresis characteristics. Also, change the video display state
There is a feature in the point of improvement.

The liquid crystal display of the present invention has a
The magnitude of the signal applied to the pixels arranged in a matrix
This is a liquid crystal display device capable of performing multi-gradation display,
A switching element connected to a pixel in the liquid crystal panel; a first X signal line for transmitting a signal for activating the switching element and a second X signal line for transmitting a signal for inactivating the switching element;
X signal lines, a plurality of Y signal lines transmitting a video signal to the switching element, a first X drive means connected to the first X signal line, and a connection to the second X signal line Second X drive means connected to the Y signal line, and the Y drive means outputs a predetermined voltage for reducing the transmittance of the liquid crystal panel during a first period. , The first X drive means is provided with the first X drive means.
A signal for bringing the switching element into an operation state is provided on a signal line.
Outputs by applying a predetermined voltage to the pixels, the Y drive means said first output video signal in the second period other than the period, the second X drive means the second X signal A signal to activate the switching element is output to the line.
To apply the video signal to the pixel,
The polarity of the video signal applied to the pixel at a predetermined cycle.
Output video signals so that the signals have the opposite polarities .

According to another aspect of the present invention, there is provided a liquid crystal display device capable of performing multi-gradation display by the magnitude of a signal applied to pixels arranged in a matrix in the liquid crystal panel. A plurality of X signal lines for transmitting a signal for turning on and off the switching element, and a plurality of Y signals for transmitting a video signal to the switching element. A line, X drive means connected to the X signal line, and Y drive means connected to the Y signal line, wherein the Y drive means is connected to the Y signal line by a first shorter than one field period . in periods continuously outputs a predetermined voltage to reduce the transmittance of the liquid crystal panel, the X drive means out of the signal for the switching element to the operating state to the X signal line And said predetermined voltage is applied sequentially to without overlapping the pixel, the Y drive means the second
Wherein the predetermined voltage and the video signal in the second period other than the first time period and
Alternately, and the X drive means outputs a signal for activating the switching element to the X signal line,
The predetermined voltage is applied to a first pixel and the video signal is applied to a second pixel.
, Respectively . Still another liquid crystal display device of the present invention is a liquid crystal display device capable of performing multi-gradation display by the magnitude of a signal applied to pixels arranged in a matrix in a liquid crystal panel. A connected switching element, a plurality of X signal lines transmitting a signal for activating the switching element and a signal for deactivating the switching element, a plurality of Y signal lines transmitting a video signal to the switching element, X
X drive means connected to a signal line, and Y drive means connected to the Y signal line, wherein the Y drive means outputs a predetermined voltage for reducing the transmittance of the liquid crystal panel during a first period. The X drive means outputs a signal for activating the switching element to the X signal line to simultaneously apply the predetermined voltage to the pixels in a plurality of pixel rows, and applies the predetermined voltage to the pixels in the plurality of pixel rows. Are sequentially applied to pixels other than the plurality of pixel rows without overlapping, the Y drive unit outputs a video signal in a second period other than the first period, and the X drive unit outputs the video signal to the X signal line. The image signal is applied to the pixel by outputting a signal for activating a switching element.

[0024]

[0025]

The liquid crystal projection television of the present invention is
The liquid crystal display device is configured by using a liquid crystal display device as a light valve. And drive. In addition, a schlieren optical system is used as the projection optical system,
By shielding scattered light and projecting parallel light on a screen, a display image with high brightness and high contrast can be realized.

[0027]

The polymer-dispersed liquid crystal has a hysteresis characteristic as apparent from FIG. Therefore, the voltage V ₀
The transmittance at the time of application differs between when V _{2 is changed} to V ₀ and when V _{1 is changed} to V ₀ . However, once the voltage application time is always transmittance V ₀ if so using only applied to the rising direction voltage V ₃ may be a T ₂ of the C points. The use of only the falling direction so V ₄ conversely can always be a T ₁ of the point d. In the present invention,
A common voltage is applied to the pixels of a row or two rows to reduce the transmittance of the liquid crystal, and after a lapse of a predetermined period, display image data is written to the pixels of the row, that is, only the rising direction is used. Therefore, the hysteresis characteristic can be removed, and a good gradation display can be performed. In addition,
In the light, the common voltage is applied to the liquid crystal layer (see paragraph number 0043).
Or a voltage with a large absolute value (see paragraph number 0076)
To reduce the transmittance of the liquid crystal layer, and this transmittance decreases
The scanned position is scanned in synchronization with the field period (see FIG. 3).
4). This display state was implemented and one point on the screen was observed.
Consider the case. In this display state, an image is displayed for each field.
Image data display, transmittance reduction display (black display (paragraph number 00)
43)) is displayed repeatedly. In other words, image data
Display time is intermittently displayed (intermittent display)
Become. If you look at the video data display in this intermittent display state,
A good display state can be realized without the contour blur of the image.
Therefore, in the present invention, the polymer dispersed liquid crystal hysteresis
The video characteristics while realizing good video display
be able to.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of the liquid crystal display device according to the first embodiment of the present invention. FIG. 1 shows a part of the source drive IC 13, the liquid crystal panel 18, the gate drive IC 14, and the drive control circuit 26 of FIG. It is extracted and shown in detail.

The liquid crystal material of the liquid crystal panel used in the liquid crystal display device of the present invention is preferably a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal, and a mixture containing one or more liquid crystal compounds or a substance other than the liquid crystal compound. It may be. Note that among the liquid crystal materials described above, a cyanbiphenyl-based nematic liquid crystal is most preferable. As the resin material, a transparent polymer is preferable, and any of a thermoplastic resin, a thermosetting resin, and a photocurable resin may be used. However, an ultraviolet curing type is used in view of easiness of a manufacturing process, separation from a liquid crystal phase, and the like. It is preferred to use the resin of As a specific example, an ultraviolet curable acrylic resin is exemplified, and a resin containing an acrylic monomer or acrylic oligomer which is polymerized and cured by irradiation with ultraviolet light is particularly preferable.
When these are irradiated with ultraviolet rays, only the resin undergoes a polymerization reaction to become a polymer, and only the liquid crystal undergoes phase separation.
At this time, when the amount of liquid crystal is small compared to the resin component, independent droplet-like liquid crystal is formed. On the other hand, when the amount of liquid crystal is large, the resin matrix contains particles in the liquid crystal material.
The liquid crystal exists in a shape or a network, and is formed so that the liquid crystal forms a continuous layer. At this time, unless the particle size of the droplet-like liquid crystal or the pore size of the polymer network is uniform to some extent, and the size is not in the range of 0.1 μm to several μm, the scattering performance of incident light is poor and the contrast is low. Does not go up. Preferably, the particle size of the droplet-shaped liquid crystal or the pore size of the polymer network is in the range of 0.5 μm to 1.5 μm. For this reason, the material must be a material that can be cured in a short time, such as an ultraviolet curable resin. The orientation ratio between the liquid crystal material and the resin material is 9: 1 to 1: 9, and particularly, 2:
A range of 1-1: 2 is preferred.

The voltage generation circuit 22 is a circuit for generating a voltage having the same potential as the common voltage. Specifically, the voltage is extracted from a voltage source having a predetermined potential by a voltage dividing ratio of a resistor. However, the active matrix type liquid crystal panel has a parasitic capacitance and the like inside, and the OV potential applied to the pixel electrode does not become the common voltage. Therefore, the resistor is configured as a volume resistor so that the voltage can be adjusted and output. The voltage often deviates from the common voltage by about 1V. Here, for ease of explanation, it is assumed that when a common voltage is applied to the pixel electrode, no voltage is applied to the liquid crystal layer above the pixel electrode. That is, the voltage applied to the liquid crystal at the common voltage is regarded as OV.

The switching circuit 23 synchronizes with a clock for one half of one horizontal scanning period (hereinafter referred to as 1H) and outputs a video signal output from the gain control circuit 21 and a common signal output from the voltage generation circuit 22. The voltage is alternately switched and output. Therefore, a signal in which the video signal and the common voltage are alternately repeated is output.

Gate drive ICs 14a, 14b, 14
c has a shift register therein, and the data in the shift register is shifted by one bit at the rise of the clock applied to the clock signal line CK. Further, the start pulse applied to the start pulse signal line at the rising edge of the clock is taken into the shift register as data. When an “H” level logic signal is applied to the enable signal line, the data in the shift register is reflected,
An on-voltage is output to the gate signal. When the logic signal is at the “L” level, an off voltage is output to all gate signal lines connected to the output terminals of the gate drive IC regardless of the data in the shift register. The data in the shift register is shifted in synchronization with the clock,
When the shift is performed to the last stage, it is output from the carry pulse signal line and becomes the start pulse of the next gate drive IC.

The selection circuit 12 operates with a 1/2 H clock, performs a multiplexer operation based on the data of the X control circuit 11, and sends an "H" or "L" logic signal to an arbitrary enable signal line. I do. The selection circuit 12
Operate in synchronization with the switching circuit 23.

The X control circuit 11 performs one vertical scanning period (hereinafter, 1
Before the start of the gate drive IC 14a, a clear pulse is output, and the pulse becomes a start pulse of the gate drive IC 14a. This clear pulse is gradually shifted in synchronization with the shift register circuit of the gate drive IC to a clock, but the carry pulse is output from the gate drive IC 14 a, a start signal at the time this pulse becomes the start pulse of the gate drive IC14b A start pulse (hereinafter referred to as a V start pulse) is output to the line. The V start pulse serves as a start pulse for the gate drive IC 14a. The V start pulse is output so that the display image data in one vertical scanning period coincides with a certain point in time.

The gain control circuit 21 is an amplifier that amplifies the input video signal so as to be compatible with the electro-optical characteristic range of the liquid crystal panel. In general, a polymer-dispersed liquid crystal panel has a rise voltage of 1.5 to 2.0 V and a voltage at which the maximum transmittance is about 6.0 V to 7.0 V. Adjust the signal amplitude.

Hereinafter, (FIG. 1), (FIG. 2) and (FIG. 5)
The operation of the liquid crystal display device of the first invention will be described with reference to FIG. FIG. 5 is a timing chart of the liquid crystal display device according to the first embodiment of the present invention. The description will be made on the assumption that the number of gate signal lines of the liquid crystal panel is 240 or less.

First, while the gain of the video signal is adjusted by the gain control circuit 21 as described above,
The voltage generation circuit 22 outputs a common voltage. The switching circuit 23 switches between the video signal and the common voltage with a 1/2 H clock. The output signal waveform of the switching circuit 23 is shown as a video signal (S ₁ ) in FIG. Here, the video signal (S ₁ ) is assumed to be a signal applied to the source signal line S ₁ . The signal is input to the phase division circuit 24. The phase division circuit 24 outputs two video signals of positive polarity and negative polarity of the input video signal. Next, the phase division circuit 2
The two positive and negative video signals output from 4 are input to an output switching circuit 25. The output switching circuit 25 outputs a video signal whose polarity is inverted for each field, and outputs this video signal to the source drive IC 13. The source drive IC 13 performs a level shift, D / A conversion, and the like of the video signal according to a control signal from the drive control circuit 26, and applies the video signal to the liquid crystal panel 18 in synchronization with the gate drive IC 14.

The switching circuit 23 is inserted at the point a in FIG. 2 (FIG. 2), and the common voltage generated by the voltage generating circuit 22 and the video signal output from the output switching circuit 25 are synthesized at the point a. It is clear that the video signal (S ₁ ) of 5) can be realized.

The liquid crystal panel 18 displays an image from the position where the gate signal line G _i corresponds. First, when the gate drive IC 14c is writing display image data to the liquid crystal panel 18 at the bottom of the screen, a clear pulse is input from the X control circuit 11 to the gate drive IC 14a as a start pulse. The selection circuit 12 applies a logic signal to the enable terminals of the gate drive ICs 14a and 14c at a cycle of 1/2 H, and alternately outputs an ON voltage or an OFF voltage to the gate signal line based on the data of the shift register circuit ( Hereinafter, this state is referred to as an active state, and a state in which an off voltage is output to all gate signal lines (hereinafter, referred to as an active state).
(Called a non-active state) . When the display image data is applied to the source signal line, the gate drive IC 14c is controlled to the active state, and when the common voltage is applied, the gate drive IC 14a is controlled to the non-active state.

Therefore, when the start pulse becomes the start pulse of the gate drive IC 14b, the common voltage is applied to all the pixels connected to the output terminal of the gate drive IC 14a, and the voltage is not applied to the liquid crystal. Become. Next, the gate drive IC 14b
, A V start pulse is output at the timing of the display pixel data of the first row of the video signal, and this pulse is input as a start pulse of the gate drive IC 14a. This time, the selection circuit 12
The gate drive ICs 14a and 14b
The active state and the non-active state are alternately switched in a cycle . When the display pixel data is applied to the source signal line, the gate drive IC 14a is in the active state, and when the common voltage is applied, the gate drive IC 14a is in the active state.
C14b is activated. Gate drive I
C14c is constantly brought into the non-active state.

[0041] As described above, the image is displayed from the pixel connected to the gate signal lines G ₁ in sequence. When the clear pulse becomes the start pulse of the gate drive IC 14b, the V start pulse is changed to the gate drive IC 14b.
Although it is described that the voltage is applied to 14a, the invention is not limited to this. Since the fall time of the polymer-dispersed liquid crystal is about 1 millisecond for a high-speed liquid crystal , the transmission time of the clear pulse and the V start pulse may be at least 1 millisecond apart.

Hereinafter, a method of driving the liquid crystal display device according to the first embodiment of the present invention will be described with reference to the drawings .
You. (FIG. 6), (FIG. 7) and (FIG. 8) are explanatory diagrams of a driving method of the liquid crystal display device in the embodiment of the present invention. (FIG. 6)
(Figure 7) Oite (FIG. 8), one square represents one pixel, X marks indicate pixels where the common voltage is applied. Note that, for ease of explanation, the display content of blank display pixels is not limited. The above applies to the following drawings.

First, the clear pulse is applied to the gate drive I
The common voltage is applied to C14a and is output to each source signal line in synchronization with the shift of the clear pulse. Accordingly, the common voltage is written to the pixels from the upper row of the screen of the liquid crystal panel, and each display pixel to which the common voltage is written gradually scatters light due to the falling characteristic of the liquid crystal. In this embodiment, a description will be given on the assumption that the pixel performs black display in a light scattering state. After 0.5 ms or more, preferably 1 ms or more after the application of the clear pulse, the V start pulse is applied to the gate drive IC 14.
a. However, if the interval between the clear pulse and the V start pulse is too long, the black display portion of the display image becomes large and the display image becomes relatively dark. If the black display part is small, the display image will not be dark, and the black display part will not be visually seen because it moves at a period of 1/60 second. According to the experiment, good gradation display can be performed by using only the rising direction in the hysteresis characteristic of FIG.
Further, even if the display image is a moving image, it does not change so much as the display image of the next field. That is, if attention is paid to only one pixel, the amount of change in the written voltage is not large.
Therefore, once the common voltage is written to the pixel and the scattering of the liquid crystal of the pixel is increased by a predetermined amount, an image can be constantly displayed only in the rising direction, and it is not necessary to complete the scattering state.

Next, as shown in (Fig. 7), in turn sequentially writes the display image from the upper portion of the liquid crystal panel a _j, and b _j .......... Rows for writing the common voltage are also shifted sequentially. The image is displayed as described above. Therefore, display image data is written into each pixel after a predetermined time has elapsed after the common voltage has been written. FIG. 8 shows a state of the display image at a certain time.

FIG. 34 shows the method of driving the liquid crystal display device of the present invention more qualitatively. In FIG. 34 , the row A is a row where the common voltage is written, and the row A is a row where the display image data is written. Therefore, the row of the area A is the area where the common voltage is written, the area B is the area where the display image of the current field is displayed, and the area C is the area where the display image of the previous field is displayed. Rows a and b move in the scanning direction at a predetermined distance. As described above, a signal whose polarity is inverted for each field is applied to the liquid crystal panel 18.
In addition, signals of opposite polarities are applied to adjacent source signal lines. This reverse polarity means that if a positive signal is applied to the first source signal line at a certain time, a negative signal is applied to the second source signal line adjacent to the first source signal line. Means that it is. It goes without saying that the signals applied to the first and second source signal lines not only have different polarities, but also have different amplitude values of the video signal depending on the displayed image. The state at that time is shown in FIG. In FIG. 24, one square means one pixel, + display indicates that a positive voltage is maintained, and one display indicates that a negative voltage is maintained. . If the state of FIG. 24A is a driving state at a certain time, that is, a certain field, the driving state after one field is as shown in FIG. 24B. By performing the above driving, flicker can be significantly reduced. This driving method is used as the liquid crystal display device of the present invention and its driving method. In FIG. 24, the polarity of the pixel adjacent in the column direction is changed, but it is clear that the polarity of the pixel adjacent in the row direction may be changed.

Next, a liquid crystal display device according to a second embodiment of the present invention will be described. The second embodiment of the present invention is the same as the first embodiment of the present invention in the points shown by the blocks in FIG. (FIG. 9) is a diagram showing a portion corresponding to (FIG. 1) of the first invention. It is assumed that 240 or more gate signal lines of the liquid crystal panel 18 are formed.

FIG. 10 shows an operation timing chart of the gate drive IC. The difference from the gate drive 14C shown in FIG. 1 is that there is a field signal line FD. When the logic signal of the “H” level is applied to the field signal line FD, _two gate signal lines G ₁ , G ₂ , G ₃ , and G ₄ are output in response to the clock.
Further, when the logic signal of the “L” level is applied, the ON voltage is applied only to the gate signal line G ₁ during the first clock, and thereafter, the gate signal lines G ₂ and G ₃ are synchronized with the clock. , G ₄ , G _5, and two on-voltages are output. The other points are the same, for example, switching between the active state and the non-active state by the logic signal of the enable signal line.

FIG. 11 is a timing chart for explaining the operation of the liquid crystal display device according to the second embodiment of the present invention. A clear pulse is input to the gate drive IC 71a as a start pulse at the bottom of the screen, that is, when the gate drive IC 71C is writing the display image to the pixels for each row. The selection circuit 12 provides enable terminals EN1 and E of the gate drive ICs 71a and 71c at a cycle of 1/2 H.
A logic signal is applied to Nx to alternately switch between an active state and a non-active state . When a common voltage is applied to the source signal line, the gate drive IC 71
When a is active and display image data is being applied to the source signal line, the gate drive IC 71c is activated. In addition, as shown in FIG.
Since the number of ON voltages output to the gate signal lines is two each, a signal is written to two rows of pixels, and
It is shifted by 2 gate signal lines to 1H.

The clear pulse is a gate drive IC.
At the time when the start pulse of the pixel 71b is generated, the common voltage is applied to all the pixels connected to the output terminal of the gate drive IC 71a, and no voltage is applied to the liquid crystal 17 of the pixel.
A light scattering state to gradually in accordance with the falling characteristics of the liquid crystal. Next, after a clear pulse is input to the gate drive IC 71b, a V start pulse is applied to the gate drive IC 71b.
It is inputted as a start pulse of 71a. At this time, needless to say, the timing is adjusted so that the display image data to be written to the pixels in the first row is applied to the source signal lines. The selection circuit 12 alternately switches the gate drive ICs 71a and 71b between the active state and the non-active state at a period of 1/2 H. When the display image data is applied to the source signal line, the gate drive IC 71a is in an active state. When the common voltage is applied to the source signal line, the gate drive IC 71a is in the active state.
1b is activated. In the active state, two adjacent gate signal lines are simultaneously turned on.
The gate drive IC 71c is constantly brought into a non-active state.

As described above, when two gate signal lines are simultaneously turned on and the same signal is written to two rows of pixels,
In the field, there are only 240 lines of display image data and 2
One screen is completed in the field. CRT televisions display images one by one. Since the liquid crystal panel is a matrix type display panel, it is difficult to perform interlaced scanning for each line, and even if it is performed, it is not used because the display screen becomes dark. As described above, in the first field, the gate signal lines G _2i-1 and G _2i (where i is an integer) are turned on simultaneously as a set.
After a common voltage is applied to the pixel and a predetermined time elapses, display image data is written to the pixel to which the common voltage has been applied. In the second field, the gate signal line G
_2i-2 and G _2i-1 (where G ₀ does not exist) are turned on at the same time as a set, and after a predetermined time elapses after the common voltage is applied to the pixel, the display image data is applied to the common voltage. Are written to the pixels. Therefore, the display image of the pixels in each row is a display image of an average of the data of the first field and the data of the second field. As described above, in the liquid crystal display device according to the second embodiment of the present invention, the field clock signal line is provided in the gate drive IC, and the control is performed by the X control circuit 72. Driving can be performed at 1/2 H.

Hereinafter, the second embodiment of the present invention will be described with reference to the drawings.
Method for driving a liquid crystal display device in embodiment
I do. FIG. 12 shows a liquid crystal according to a second embodiment of the present invention.
FIG. 4 is an explanatory diagram of a driving method of the display device . First, a clear pulse is applied to the gate drive IC 71a, and a common voltage is output to each source signal line in synchronization with the shift of the clear pulse. At this time, the gate signal lines are G ₁ , G ₂ ,
G ₃ , G ₄ ,..., G _2i-1 , G _2i are applied with two ON voltages. The sync to be shifted is 1H. As described above, the common voltage is written to the pixels of two rows. The pixels to which the common voltage is written gradually scatter light due to the falling characteristics of the liquid crystal. When the liquid crystal scatters light, the light is shielded by the Schlieren optical system, so that the pixel displays black. If the number of gate signal lines of the liquid crystal panel is 480 and the number of output terminals of the gate drive IC is 60, 480/60 = 8 gate drive ICs are used for the liquid crystal panel. One volt is 1/60 ≒ 16 milliseconds. Therefore, the time during which data is shifted in the gate drive IC is 16/8/2 milliseconds. So Gate Drive I
The time when the clear pulse input to C71a becomes the start pulse of the gate drive IC 71b is about 2 milliseconds after the clear pulse is output from the X control circuit 72. After the clear pulse becomes a start pulse of the gate drive IC 71b, a V start pulse is output from the X control circuit 72 and becomes a start pulse of the gate drive IC 71a. That is, a V start pulse is output after a lapse of 2 milliseconds. Therefore, the range of the display area in which the common voltage is written is 2 milliseconds, which is 1/8 of the pixel display.

Next, from above the liquid crystal panel,
The gate signal line G1, G2, G3, G4, ···, G2i-
The on-voltage is output for each of two lines, ie, 1, G2i, and the displayed image is V
The start pulse is written by moving in the shift register. As is clear from the video signal (Si) in the timing chart of FIG. 11, the display image data is written to the pixels in the first half of 1H, and the common voltage is written in the second half. Therefore, it appears that the row in which the display image is written and the row in which the common voltage is written are sequentially shifted. In addition,
The writing order of the display image data and the common voltage may be reversed . This is the same in other inventions. (Figure 1
2) shows the state of the display image at a certain time. In FIG. 12, A is the area where the common voltage is written, B is the area where the display image data of the current field is written, and C is the area where the display image data of the previous field is written.

When the clear pulse becomes the carry pulse of the gate drive IC at the last stage, the next field is started. First, similarly to the above, the clear pulse output from the X control circuit 72 becomes the start pulse of the gate drive IC 71a. First, first only the gate signal line G ₁ is turned on, from the following _{G 2, G 3, G 4} , G 5 and the ON voltage by two is applied, have the common voltage is written into each pixel
Good. The cycle to be shifted is 1H. When the start pulse becomes the start pulse of the next stage gate drive IC 71b, the V start pulse is applied to the gate drive IC 71b.
a. A common voltage is written in the column direction as the clear pulse moves, and an image is displayed in the column direction as the V start pulse moves . Therefore, before to display fields and the current field shifted line by line, for example, x ₂ rows is the display pixel display was mixed in x ₂ rows x ₂ rows and the current field of the previous field. FIG. 13 shows a state of the display pixel at a certain time. As described above, one frame is completed in two fields, and the display of one screen is completed.

Next, a liquid crystal display device according to a third embodiment of the present invention will be described. Since the block diagram of the third embodiment of the present invention is substantially the same as that of the first embodiment (FIG. 2), the description will focus on the differences from the liquid crystal display device of the first or second embodiment. (Figure 1
4) is a diagram showing a portion corresponding to (FIG. 1) of the first present invention. The gate signal lines of the liquid crystal panel 18 are 240
It is assumed that more than one book is formed. (FIG. 15) and (FIG. 16) are timing charts for explaining the operation of the liquid crystal display device of the third invention.

One pixel is formed with two TFTs as switching elements. These two TFTs are connected to different gate signal lines. Two T
The source terminals of the FT are connected to the same source signal line. Gate drive ICs are mounted on the left and right sides of the liquid crystal panel. Gate signal lines are drawn left and right every other line,
It is connected to a gate drive IC. In FIG. 14 , the odd-numbered gate signal lines correspond to the gate drive IC (hereinafter referred to as left gate drive IC) stacked on the left, and the even-numbered gate signal lines correspond to the right gate drive IC (hereinafter, right gate drive IC). Connected).

The X control circuit 103 has a start pulse signal line, a clock signal line, and an enable signal line corresponding to the left / right gate drive IC. Note that the clock signal line may be shared.

Hereinafter, the operation of the liquid crystal display device according to the third embodiment of the present invention will be described. The video signal has a vertical blanking time (hereinafter, referred to as V blanking). Usually, V blanking is about 10% of 1V, so that time is about 2%.
Less than a millisecond. A start pulse is applied to the left gate drive IC 101a at the start of V blanking. At the same time, a common voltage is applied to each source signal line. First, the gate signal line G ₁₁ at the first clock is turned on, the common voltage to the TFT connected to the gate signal line G ₁₁ is written. That is, the common voltage is written to the pixels of two rows . Gate signal line G at next clock
₁₃ turns on, and the common voltage is written to the pixel connected to the gate signal line. That is, the common voltage is written to the pixels of two rows . As described above, the odd-numbered gate signal lines are sequentially turned on, and the common voltage is written to the pixels every two rows.

When the V blanking is completed, the timing is adjusted so that the video signal has display image data. The X control circuit 103 applies a start pulse to the right gate drive IC 101c. At the same time, common voltage and display image data are repeated at 1 / 2H cycle on each source signal line .
The resulting signal is applied. When display image data is applied to the source signal line, the even-numbered gate signal lines are turned on, and the display image data is written to the pixels of two rows.
For example, TFT gate signal lines G ₁₂ is connected to the gate signal line if the on is turned on, the display image data is written. Shifted by one bit in the next clock, the gate signal line G ₁₄ is turned on, TFT connected to the gate signal line is turned on, the display image data is written. Therefore, the left gate drive IC
Then, the common voltage is written to the pixels for each row, and the display image data is written to the pixels for each row by the right drive IC so as to follow the common voltage. The time until the display image data is written in the row where the common voltage is written is the V blanking time. Note that the video signal (S
In 1), the polarity is represented by negative polarity, but may be represented by positive polarity. However, in the next field, the display image data of the opposite polarity is written to the pixel, and apparently, the pixel needs to be driven by AC.

In the next field, the timing chart is as shown in FIG. First, with the start of V blanking, a start pulse is applied to the right gate drive IC 101c.
Is applied to At the same time, a common voltage is applied to each source signal line. After the start pulse is applied, at the first clock, the gate signal line G ₁₂ is turned on, the common voltage to the pixels connected to the gate signal line G ₁₂ is written.
Thereafter, the even-numbered gate signal lines are turned on in synchronization with the clock, and the common voltage is written to the pixels connected to the gate signal lines. That is, the common voltage is written every two rows.

When the V blanking ends, the X control circuit 103 sends a start pulse to the left gate drive IC 101
It applied to a. At the same time, a signal in which a common voltage and display image data are repeated at a 1 / 2H cycle is applied to each source signal line. When display image data is applied to the source signal line, the odd-numbered gate signal lines are in the ON state,
When the common voltage is applied, the even-numbered gate signal lines are turned on. That is, the common voltage and the display image data are alternately written to the pixels. The state is shown in a timing chart (FIG. 16). In the liquid crystal display device according to the third aspect of the present invention, a common voltage is applied to pixels by utilizing V blanking.
Write, and then display image data . The gate signal lines are also drawn alternately left and right. Therefore, the number of control signal lines of the gate drive IC can be reduced as compared with the second aspect, and the drive becomes easy. Note that the time from writing a common voltage to a pixel to writing display image data to the pixel is shorter than V blanking.
It may or may not be longer. This can be dealt with by changing the operation of the X control circuit.

Hereinafter, the third embodiment of the present invention will be described with reference to the drawings.
The driving method of the liquid crystal display device according to the embodiment is described. (FIG. 17) (FIG. 18) (FIG. 19)
FIG. 9 is an explanatory diagram of a driving method of the liquid crystal display device in the example of FIG. First, at the start of V blanking before the first field, the odd-numbered gate signal lines are sequentially turned on ,
The common voltage is written to the pixels connected to the gate signal line. The state is shown in FIG. When the V blanking is completed, the even-numbered gate signal lines and the odd-numbered gate signal lines are alternately turned on, and display image data is applied to each source signal line when the even-numbered gate signal line is on, When the odd-numbered gate signal lines are on, a common voltage is applied. This state (FIG. 18)
Shown in In FIG. 18, A is a display image area in which the common voltage is written, B is a display image area in which the display image data of the current field is written, and C is a display in which the display image data of the previous field is written. This is an image area.

In the next field, even-numbered gate signal lines are sequentially turned on at the start of V blanking, and the common voltage is written to the pixels connected to the gate signal lines. When the V blanking ends, the odd-numbered gate signal lines and the even-numbered gate signal lines become 1 /
It is turned on alternately in a cycle of 2H. When the odd-numbered gate signal lines are turned on, display image data is applied to each source signal line, and when the even-numbered gate signal lines are turned on, a common voltage is applied to the source signal lines. That is, the common voltage to the pixel connected to the even-numbered gate signal line,
The odd-numbered pixels connected to the gate signal line of the written display image data, respectively. This state (FIG. 19)
Shown in It can be seen that the writing position of the display image data is shifted by one line as compared with FIG.

Hereinafter, a liquid crystal projection television according to the present invention will be described with reference to the drawings. FIG. 20 is a configuration diagram of the liquid crystal projection television of the present invention. However, components unnecessary for the description are omitted. In FIG. 20, 131
Is a condensing optical system, which has a concave mirror and a metal halide lamp of 250 W as light generating means inside.
The concave mirror is configured to reflect only visible light . Further, an ultraviolet cut filter is arranged at an emission end of the light collecting optical system 131. Reference numeral 132 denotes an infrared cut mirror that transmits infrared light and reflects only visible light .
However, the infrared cut mirror 132 is a focusing optical system 131
Needless to say, it may be arranged inside the. Also,
133a is a blue dichroic mirror (hereinafter referred to as BDM), and 133b is a green dichroic mirror (hereinafter GD)
133c is a red dichroic mirror (hereinafter referred to as RDM). It should be noted that the R
The arrangement of the DM 133c is not limited to the order shown in the figure, and it goes without saying that the last RDM 133c may be replaced with a total reflection mirror.

Reference numerals 134a, 134b and 134c denote liquid crystal panels of the above-mentioned first, second or third liquid crystal display device of the present invention. In addition, among the liquid crystal panels,
The liquid crystal panel 134c that modulates the R light has a larger droplet-shaped liquid crystal particle diameter or a larger liquid crystal film thickness than other liquid crystal panels. This is because the scattering characteristic decreases as the light becomes longer in wavelength. The particle size of the water-droplet liquid crystal can be controlled by controlling the ultraviolet light at the time of polymerization or by changing the material used. The liquid crystal film thickness can be adjusted by changing the bead diameter. 135
a, 135b and 135c are lenses, 137a and 13
7b and 137c are projection lenses, 136a and 136b
And 136c are apertures as apertures. Incidentally, 135, 136 and 137 constitute a schlieren optical system. However, the schlieren optical system according to the present invention has an aperture, and has a different configuration from the original schlieren optical system. The set of 135, 136, and 137 is called a projection lens system unless there is a particular problem. The aperture is the FN of the lens 135.
o. Obviously this is not necessary when is large.

The arrangement of the projection lens system is as follows. First, the polymer dispersed liquid crystal panel 13 of the liquid crystal display device
The distance L between the lens 4 and the lens 135 and the distance between the lens 135 and the aperture 136 are substantially equal. The lens 135 is selected so that the light collection angle θ is about 8 degrees or less. Further, the opening diameter D of the aperture 136 is set to about 1 cm when the distance L is 10 cm. The above-described projection lens system plays a role of transmitting parallel rays transmitted through each liquid crystal panel and blocking light scattered by each liquid crystal panel. As a result, a high-contrast full-color display can be realized on the screen. If the aperture diameter D of the aperture is reduced, the contrast is improved. However, the image brightness on the screen decreases.

The thickness of the liquid crystal layer of the liquid crystal panel of the present invention is 10
In the case of １５15 μm, the condensing angle θ of the lens must be at least 8 degrees or less. Especially around 6 degrees is the best,
At that time, the contrast is 200: 1 at the center of the screen, and when projected on a 40-inch screen with a rear television, is 400 ft or more at a screen gain of 5, and
Compared with the T-projection television, the same or higher screen brightness was obtained. The aperture diameter of the aperture at that time is 1
cm and the distance L were around 10 cm. More specifically, the configuration diagram of FIG. 20 is shown by a perspective view shown in FIG. In FIG. 21, 141 and 142 are lenses, 1
43 is a mirror, and 144a, 144b and 144c are projection lenses or projection lens systems.

The operation of the liquid crystal projection television according to the present invention will be described below. Since the respective modulation systems of R, G, and B light have almost the same operation, the modulation system of B light will be described as an example. First, white light is emitted from the condensing optical system 131, and the B light component of this white light is BDM1.
It is reflected by 33a. This B light is incident on the polymer dispersed liquid crystal panel 134a. Polymer dispersed liquid crystal panel 134
a modulates the light by controlling the scattering and transmission state of the incident light by a signal applied to the pixel electrode as shown in FIGS. 3 (a) and 3 (b).

The scattered light is blocked by the aperture 136a, while the parallel light or light within a predetermined angle is
6a. The modulated light is enlarged and projected on a screen (not shown) by the projection lens 137a. As described above, the B light component of the image is displayed on the screen. Similarly, the polymer dispersed liquid crystal panel 134b modulates the light of the G light component, and the polymer dispersed liquid crystal panel 134c modulates the R component.
By modulating the light of the light component, a color image is displayed on the screen.

Hereinafter, a driving circuit and a driving method of the liquid crystal projection television according to the present invention will be described. FIG. 22 is an explanatory diagram of a drive circuit of the liquid crystal projection television according to the present invention. In FIG. 22, 134c is a liquid crystal panel that modulates R light, 134b is a liquid crystal panel that modulates G light, 134a is a liquid crystal panel that modulates B light, and R1 and R2 and a transistor Q input to the base. A phase division circuit for generating a video signal of a positive polarity and a video signal of a negative polarity is configured, and 24 in FIG. 2 corresponds thereto. Reference numerals 151a, 151b and 151c denote output switching circuits for outputting an AC video signal whose polarity is inverted for each field to the liquid crystal panel, and corresponds to 25 in FIG. After the gain of the video signal is adjusted to a predetermined value, the video signal is divided into signals corresponding to the R, G, and B lights. These video signals are referred to as a video signal (R), a video signal (G), and a video signal (B), respectively.
Each video signal (R), (G), (B) is input to each phase division circuit, and two positive and negative video signals are generated by this circuit.

Next, the above-mentioned three video signals are inputted to respective output switching circuits 151a, 151b, 151c, and output video signals of which polarity is inverted for each field by these circuits. The reason for inverting the polarity for each field is to prevent the deterioration of the liquid crystal by applying an AC voltage to the liquid crystal as described above. Next, the video signals output from the respective output switching circuits are input to the source drive IC 13. The drive control circuit 26 synchronizes the source drive IC 13 with the gate drive IC 14 and displays an image on a liquid crystal panel.

Next, the visibility of the human eye will be described.
The human eye has the highest sensitivity near the wavelength of 555 nm. Of the three primary colors of light, green is the highest, red is the next, and blue is the least sensitive. In order to obtain a luminance signal proportional to this sensitivity, it is sufficient to add 30% of red, 60% of green and 10% of blue. Therefore, in order to obtain white color in a television image, it is only necessary to add R: G: B = 3: 6: 1. Further, as described above, the liquid crystal needs to be driven by an alternating current. The AC drive is performed by alternately applying a positive polarity signal and a negative polarity signal to a voltage (ie, a common voltage) applied to the opposite electrode of the liquid crystal panel. In the present embodiment, the state in which a positive signal is applied to the liquid crystal panel to modulate the light having the luminosity n is + n, and the negative signal is applied to modulate the light having the luminosity n. The present state is represented by -n.

For example, light of R: G: B = 3: 6: 1 is applied to the liquid crystal panel, a positive signal is applied to the R and B liquid crystal panels, and a negative signal is applied to the G liquid crystal panel. If a sex signal is applied, it is expressed as + 3−−6 · + 1. Note that R: G: B = 3: 6: 1 is NTSC
In a liquid crystal projection television, the above ratio varies depending on the characteristics of a lamp and a dichroic mirror of a light source. (FIG. 22) shows + 3-6
As indicated by +1, light of R: G: B = 3: 6: 1 is applied, and the R and B liquid crystal panels receive a positive signal and the G liquid crystal panel receives a negative signal. This shows a state where the voltage is applied. After one field, -3 ・ +6 ・ −
A signal application state expressed as 1 is obtained.

FIG. 23 shows a waveform of a signal applied to each liquid crystal panel. (FIG. 23 (a)) is a signal waveform of the liquid crystal panel 134c for modulating the R light, (FIG. 23 (b)) is a signal waveform of the liquid crystal panel 134b for modulating the G light, (FIG. 23 (c))
Is a signal waveform of the liquid crystal panel 134a for modulating the B light. As is clear from FIGS. 23 (a), (b) and (c), the signal waveform for G light modulation has the opposite polarity to the signal waveform for R and B light modulation. Normally, even if the same signal is applied to the liquid crystal display device, there is a slight difference in the voltage held in the pixel between the even field and the odd field. this is,
This occurs because the on-current and off-current of the TFT differ depending on the polarity of the video signal, or the holding characteristics of the alignment film and the like in the positive electric field and the negative electric field differ. This difference causes a phenomenon called flicker. However, in the liquid crystal projection television of the present invention, as shown in FIGS. 24A and 24B, the polarity of the signal between adjacent source signal lines is changed, and as shown in FIG. The flicker is prevented from being visually recognized by making the polarity of the signal for the R and B light modulation opposite to that of the signal for the R and B light. The reason why the signal for G light modulation has the opposite polarity to the other is that the light intensity is R: G: B =
The ratio is 3: 6: 1, which is (R + B): G = (3 + 1): 6 = 4: 6 in consideration of the polarity of the signal and human vision, which is almost 1: 1 .

Although the liquid crystal display of this embodiment has been described as a transmissive liquid crystal panel, the present invention is not limited to this, and it is obvious that a reflective structure may be adopted. is there. In that case, the pixel electrode may be formed of a metal material.

In FIG. 14, each source terminal of the two TFTs connected to one pixel is connected to the same source signal line. However, the present invention is not limited to this.
You may connect to a different source signal line like 5).

In the liquid crystal display device and the method of driving the same according to the present invention, the common voltage is written to the pixel. However, the present invention is not limited to this, and a voltage having a large absolute value may be used. Is clear. This is because, as can be seen from FIG. 4, good gradation display is performed even when the voltage V ₄ is applied to cause the liquid crystal molecules to rise once, and to use the falling direction (the direction of the arrow below the figure). It is. In this case, in the liquid crystal projection television of the present invention (FIG. 26)
It is desirable to adopt a projection optical system and to configure so as to block transmitted light.

In FIG. 20 , the projection lens system is a schlieren optical system. However, the present invention is not limited to this. For example, as shown in FIG. Needless to say, a center shielding type optical system that projects scattered light on a screen may be used.

The structure of the liquid crystal display of the present invention is TF
The present invention is not limited to T, and is also effective for a liquid crystal display device using a two-terminal element such as a diode as a switching element.

In FIG. 20 , light is incident from the array substrate side. However, the present invention is not limited to this, and it is apparent that the same effect can be obtained by incident light from the opposite substrate. As described above, the liquid crystal display device and the liquid crystal projection television according to the present invention are not affected by the incident direction of light.

Further, in the embodiment of the liquid crystal projection television according to the present invention, the description has been made by describing as a rear type liquid crystal projection television. However, the present invention is not limited to this. It goes without saying that a liquid crystal projection television may be used. Furthermore, in the liquid crystal projection television of this embodiment, the color separation is performed by the dichroic mirror. However, the present invention is not limited to this. For example, the color separation may be performed using an absorption color filter.

Further, in the liquid crystal projection type television of this embodiment, one projection lens system is provided for each of the R, G and B light modulation systems. However, the present invention is not limited to this. It is needless to say that the display image modulated by the liquid crystal panel may be combined into one, and then may be incident on one projection lens system and projected.

[0082]

As described above, the liquid crystal display device of the present invention has the following features .
Since a polymer-dispersed liquid crystal is used, a high-luminance screen twice or more as compared with a liquid crystal display device using a TN liquid crystal can be obtained. In addition, the liquid crystal panel has good light scattering characteristics and transmission characteristics, and a contrast of 200: 1 or more can be obtained. Therefore, a large-screen display of 100 inches or more can be easily realized by configuring a liquid crystal projection television using the liquid crystal display device of the present invention.

Further, in the liquid crystal display device and the driving method of the present invention, the display image data is written after writing the common voltage to the pixel once and causing the liquid crystal to fall. Therefore, an image is displayed using only the rising direction of the liquid crystal. The polymer dispersed liquid crystal has a problem that the voltage-transmission characteristic curves at the time of rising and falling are not the same locus,
Conventionally, the gradation display characteristics were inferior. However, according to the present invention, the gradation display characteristics are improved, and image quality higher than that of a CRT can be realized. In particular, in the liquid crystal display device according to the second aspect of the present invention, a field signal line is provided in the gate drive IC, the drive start signal line position of the gate signal line is changed in the odd field and the even field, and the gate signal lines are turned on two by two. Therefore, even if there are 480 gate signal lines, a favorable image display can be realized with the same 1 / 2H clock as in the conventional non-interlaced scanning. In addition, the common voltage is applied to the liquid crystal layer.
Pressure is applied to decrease the transmittance of the liquid crystal layer, and this transmittance is reduced.
Whether to scan a slight position in synchronization with the field period
Then, the image data display state becomes the intermittent display state. That
Good image display without moving image outline
The state can be realized. Therefore, in the present invention, the polymer component
Removes the hysteresis characteristics of
Video display can be realized.

In the liquid crystal display device according to the third aspect of the present invention, a method of writing a common voltage from a pixel at the upper end of the screen at the start of V blanking prior to writing a display image is described by drawing out alternate gate signal lines to the left and right. Take. Therefore, as compared with the liquid crystal display device of the second aspect of the present invention, the control of the gate drive IC becomes easier and the configuration becomes simpler.

In the liquid crystal projection television of the present invention, since the liquid crystal display device of the present invention is used, high brightness of the screen can be realized, and high quality images can be realized because there is no hysteresis characteristic peculiar to the polymer dispersed liquid crystal. it can. Also, by making the signal phase of the liquid crystal panel for modulating G light and the signal phase of the liquid crystal panel for modulating R and B light opposite phases, and also making the phases of adjacent rows and columns opposite phases to each other. Image display without flicker can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a liquid crystal display device of the first invention.

FIG. 2 is a block diagram of a liquid crystal display device according to an embodiment of the first invention.

FIG. 3 is a diagram illustrating the operation of a polymer dispersed liquid crystal panel.

FIG. 4 is a voltage-transmittance characteristic diagram of a polymer-dispersed liquid crystal.

FIG. 5 is a timing chart of various signal waveforms according to the liquid crystal display device of the first invention.

FIG. 6 is an explanatory diagram of a driving method of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of a driving method of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram of a driving method of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram of a liquid crystal display device according to an embodiment of the second invention.

FIG. 10 is a timing chart of various signal waveforms according to the liquid crystal display device of the second invention.

FIG. 11 is a timing chart of various signal waveforms according to the liquid crystal display device of the second invention.

FIG. 12 is a diagram illustrating a driving method of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 13 is a diagram illustrating a method for driving a liquid crystal display device according to a second embodiment of the present invention.

FIG. 14 is an explanatory diagram of a liquid crystal display device according to an embodiment of the third invention.

FIG. 15 is a timing chart of various signal waveforms according to the liquid crystal display device of the third invention.

FIG. 16 is a timing chart of various signal waveforms according to the liquid crystal display device of the third invention.

FIG. 17 is an explanatory diagram of a driving method of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 18 is an explanatory diagram of a driving method of the liquid crystal display device according to the third embodiment of the present invention.

FIG. 19 is an explanatory diagram of a driving method of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 20 is an explanatory diagram of a liquid crystal projection television according to one embodiment of the present invention.

FIG. 21 is an explanatory diagram of a liquid crystal projection television according to one embodiment of the present invention.

FIG. 22 is a partial circuit diagram of a liquid crystal projection television according to the present invention.

FIG. 23 is an explanatory diagram of a driving method of a liquid crystal projection television according to the present invention.

FIG. 24 is an explanatory diagram of a driving method of a liquid crystal projection television according to the present invention.

FIG. 25 is an explanatory view of another embodiment of the liquid crystal display device of the present invention.

FIG. 26 is an explanatory view of another embodiment of the liquid crystal projection television according to the present invention.

FIG. 27 is an explanatory view of a conventional liquid crystal display device.

FIG. 28 is a block diagram of a conventional liquid crystal display device.

FIG. 29 is an external view of a liquid crystal panel.

FIG. 30 is an explanatory diagram of an operation of a TN liquid crystal.

FIG. 31 is a timing chart of the conventional liquid crystal display device shown in FIG.

FIG. 32 is an explanatory diagram of a driving method of a conventional liquid crystal display device .

FIG. 33 is an explanatory diagram of a conventional liquid crystal projection television.

FIG. 34 is an explanatory diagram of a driving method of a liquid crystal projection television according to the present invention.

[Explanation of symbols]

11, 72, 103, 201 X control circuit 12 selection circuit 14, 71, 101 Gate drive IC 22 Voltage generation circuit 23 Switching circuit 31 Array substrate 33 Counter electrode 34 Water droplet liquid crystal 35 Polymer 36 Counter substrate 134 Polymer dispersed liquid crystal panel 136 Aperture 192 Light shield 265 TN liquid crystal display 271 Display screen

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-204628 (JP, A) JP-A-2-79816 (JP, A) JP-A-1-121822 (JP, A) JP-A-4-204 186217 (JP, A) JP-A-53-38223 (JP, A) JP-A-53-61221 (JP, A) JP-A-61-275824 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) G09G 3/00-3/38 G02F 1/133 505-580 H04N 5/66-5/74

Claims (10)

(57) [Claims] 1. A liquid crystal display device capable of performing multi-gradation display by the magnitude of a signal applied to pixels arranged in a matrix in a liquid crystal panel, comprising: a switching element connected to the pixels in the liquid crystal panel; A first X signal line and a second X signal for transmitting a signal for bringing the switching element into an operation state and a signal for bringing the switching element into a non-operation state;
A signal line; a plurality of Y signal lines for transmitting a video signal to the switching element; a first X drive unit connected to the first X signal line; and a plurality of Y signal lines connected to the second X signal line A second X drive unit, and a Y drive unit connected to the Y signal line, wherein the Y drive unit outputs a predetermined voltage for reducing a transmittance of the liquid crystal panel during a first period, The first X drive means outputs a signal for activating the switching element to the first X signal line and applies the predetermined voltage to the pixel.
It is applied to the Y drive means outputs a video signal in the second period other than the first period, the second X drive means to the operating state of the switching element to the second X signal line outputs a signal which is applied to the video signal to the pixel, the Y drive means and outputs a video signal as the polarity of the video signal applied to the pixel at a predetermined period have opposite polarities Liquid crystal display. 2. A liquid crystal display device capable of performing multi-gradation display according to the magnitude of a signal applied to pixels arranged in a matrix in a liquid crystal panel, comprising: a switching element connected to the pixels in the liquid crystal panel; A plurality of X signal lines for transmitting a signal for bringing the switching element into an operation state and a signal for bringing the switching element into a non-operation state; a plurality of Y signal lines for transmitting a video signal to the switching element; X drive means, and Y drive means connected to the Y signal line, wherein the Y drive means continuously connects the Y signal line to the liquid crystal panel during a first period shorter than one field period. A predetermined voltage for reducing the transmittance is output, and the X drive unit outputs a signal for activating the switching element to the X signal line to apply the predetermined voltage to the pixel The Y drive means alternately outputs the predetermined voltage and the video signal during a second period other than the first period, and the X drive means applies the switching element to the X signal line. And outputs a signal for setting the predetermined voltage to the first pixel.
A liquid crystal display device comprising said applying each video signal to the second pixel. 3. A liquid crystal display device capable of performing multi-gradation display by the magnitude of a signal applied to pixels arranged in a matrix in a liquid crystal panel, comprising: a switching element connected to the pixels in the liquid crystal panel. A plurality of X signal lines for transmitting a signal for bringing the switching element into an operation state and a signal for bringing the switching element into a non-operation state; a plurality of Y signal lines for transmitting a video signal to the switching element; X drive means, and Y drive means connected to the Y signal line, wherein the Y drive means outputs a predetermined voltage for reducing the transmittance of the liquid crystal panel during a first period, means simultaneously applied to a pixel of the plurality of pixels row the predetermined voltage and outputs a signal to the operating state of the switching element to the X signal line and said plurality of pixels line said predetermined voltage Sequentially applied to the pixels other than the plurality pixel rows without overlapping the pixel <br/>, the Y drive means outputs a video signal in the second period other than the first period, the X drive means outputs a signal to the switching element to the operating state to the X signal line
And applying the video signal to the pixel . 4. The liquid crystal panel is arranged in a matrix in a liquid crystal panel.
Display is performed according to the magnitude of the signal applied to the pixel.
A liquid crystal display device obtain, connected to said pixel in the liquid crystal panel switching element
And a signal for activating the switching element and a non-operating state.
A first X signal line and a second X signal for transmitting a signal
A signal line, and a plurality of Y signals for transmitting a video signal to the switching element.
Route a, the first X signal line and X de connected to the second X signal line
A live means; and a Y drive means connected to the Y signal line, wherein the Y drive means reduces the transmittance of the liquid crystal panel.
X drive means alternately outputs a predetermined voltage and a video signal to the selected first X signal line.
By outputting a signal to activate the switching element
The predetermined voltage output by the Y drive means is applied to the first
Connected to the X signal line through the switching element.
The position of the first X signal line to be applied to the pixel and to be selected is sequentially determined.
And the X drive means shifts to the selected second X signal line.
By outputting a signal to activate the switching element
The video signal output from the Y drive means is transmitted to the second
Connected to the X signal line through the switching element.
The position of the second X signal line to be applied to the pixel and to be selected is sequentially determined.
Shifting, the X drive means and the Y drive means
The area to which the predetermined voltage is applied becomes a band and is
It is driven to move in the vertical direction of the surface.
Liquid crystal display device. 5. A liquid crystal display device comprising :
Display is performed according to the magnitude of the signal applied to the pixel.
A liquid crystal display device obtain, connected to said pixel in the liquid crystal panel switching element
And a signal for activating the switching element and a non-operating state.
A first X signal line and a second X signal for transmitting a signal
A signal line, and a plurality of Y signals for transmitting a video signal to the switching element.
Route a, the first X signal line and X de connected to the second X signal line
A live means; and a Y drive means connected to the Y signal line, wherein the Y drive means reduces the transmittance of the liquid crystal panel.
X drive means alternately outputs a predetermined voltage and a video signal to the selected first X signal line.
By outputting a signal to activate the switching element
The predetermined voltage output by the Y drive means is applied to the first
Connected to the X signal line through the switching element.
The first to apply and select sequentially without overlapping the pixels
The X signal line position is sequentially shifted, and the X drive means is connected to the selected second X signal line.
By outputting a signal to activate the switching element
The video signal output from the Y drive means is transmitted to the second
Connected to the X signal line through the switching element.
The position of the second X signal line to be applied to the pixel and to be selected is sequentially determined.
The video signal is shifted to the pixel to which the predetermined voltage is applied.
Characterized in that the time until the time is over 1 millisecond
Liquid crystal display. 6. A liquid crystal display device comprising :
Display is performed according to the magnitude of the signal applied to the pixel.
A liquid crystal display device obtain, connected to said pixel in the liquid crystal panel switching element
And an on-voltage and non-operating state for bringing the switching element into an operating state.
A first X signal line for transmitting an off-state voltage for operating
A second X signal line and a plurality of Y signals for transmitting a video signal to the switching element;
Route a, the first X signal line and X de connected to the second X signal line
A live means; and a Y drive means connected to the Y signal line, wherein the Y drive means reduces the transmittance of the liquid crystal panel.
X drive means alternately outputs a predetermined voltage and a video signal to the selected first X signal line.
Outputs an on-voltage for operating the switching element
The predetermined voltage output by the Y drive means
Connected to the first X signal line via the switching element
Applied to the selected pixel, and the X drive means applies the signal to the selected second X signal line.
Outputs an on-voltage for operating the switching element
And outputs the video signal output by the Y drive means to the
Connected to the second X signal line via the switching element.
On the first X signal line and the second X signal line.
The control of whether to output the output or the off voltage is performed by the X drive.
Logic signal applied to the enable signal line of the
A liquid crystal display device characterized by being more switchable. 7. The Y drive means applies a voltage to adjacent pixels.
Video signal output so that the polarity of the video signal is reversed
And applying a video signal of opposite polarity to the adjacent pixel.
Claim 2, Claim 3, Claim 4, Claim
The liquid crystal display device according to claim 5 or 6. 8. predetermined voltage, claim 1 in which the potential is equal to or is identical to the potential of the voltage applied to the counter electrode of the liquid crystal panel, according to claim 2, claim 3, claim 4, claim
The liquid crystal display device according to claim 5 or 6 . Claim 1 9. A liquid crystal panel, which is a polymer dispersed liquid crystal panel, according to claim 2, claim 3,請
The liquid crystal display device according to claim 4, claim 5, or claim 6 . 10. A liquid crystal display device as claimed in any one of claims 9, a light generating unit, a first optical element component for guiding the light said light generating means is generated in the liquid crystal display device And a projection unit for projecting light modulated by the liquid crystal display device.