JP5604073B2 - OLED display device - Google Patents

Description

  The present invention relates to an OLED (Organic light-emitting diode) display device using an organic light-emitting diode as a light-emitting element, and in particular, an OLED display device that realizes a moving image display without blurring and a long life and low power consumption. It is about.

  Conventionally, as a display device that prevents motion blur and suppresses increase in power consumption and shortening of service life, black insertion drive is performed in the case of moving images according to the value of an identification signal that identifies whether the input data is a moving image or a still image. In the case of a still image, black insertion is not performed, and when black insertion is performed, one frame is divided into front and rear subfields, video is displayed in the previous field, and black is inserted in the subsequent field ( For example, see Patent Document 1).

  Further, since the OLED display device is a self-luminous type, if the background portion is displayed in white and the character portion is displayed in black, the power consumption is lower than in the case where the background portion is displayed in black and the character portion is displayed in white. Some text data are displayed in black and white reversed to reduce power consumption (see, for example, Patent Document 2).

JP 2007-114286 A JP 2003-108076 A

  However, since the OLED is a data hold type drive similar to the LCD, moving image blur tends to occur, and smooth moving image display has a drawback. To cope with this, the drive frequency was increased and black data was inserted. However, the increase in the drive frequency promotes the deterioration of the OLED material due to the increase in the power consumption and the increase in the current density. It was.

  Also, since there is a turn-off time for preventing moving image blur, in order to keep the luminance constant, it is necessary to increase the luminance in inverse proportion to the turn-off time. For this reason, the current density which flows into OLED increases, and the problem that the degradation rate of OLED material increases generate | occur | produces.

  Furthermore, most portable devices are battery-driven, and low power consumption is essential. Although the user uses the battery while paying attention to the remaining battery level, there may be a situation where the user has to continue using the battery even when the remaining battery level is low. Therefore, if there is an effective function that can extend the usage time of the portable device, it will be very effective for the user, and it is desired to reduce the power consumption of the display device as much as possible.

  The present invention has been made in view of the above-described points, and consumes three display modes: a moving image mode in which a moving image can be enjoyed, a standard mode that suppresses shortening of the life of the OLED material, and a monochrome mode suitable for a self-luminous display device. An object of the present invention is to obtain an OLED display device that realizes a function that can be switched by a simple method without significantly increasing power.

The OLED display device according to the present invention is an OLED display device using an organic light emitting diode as a light emitting element, and inputs a moving image mode signal and a molo black mode signal for causing the driving circuit for driving the display panel to shift from the standard mode to the moving image mode. Mode switching means for switching between the standard mode, the moving image mode, and the monochrome mode based on the monochrome mode. In the monochrome mode, the sub-pixel of one color among the plurality of sub-pixels constituting each pixel is supplied from the driving IC. Data is supplied, and the black potential existing inside the display panel is supplied to the corresponding data line without supplying data from the driving IC to the sub-pixels of the remaining color among the plurality of sub-pixels of each pixel. And

  According to the present invention, the moving image mode, the standard mode, and the monochrome mode are properly used according to the application, so that a moving image display without blurring, longer life, and lower power consumption can be achieved.

It is a figure which shows the outline | summary of the 3 mode display apparatus applied as an OLED display apparatus based on this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a function of a driving IC, illustrating an OLED display device according to an embodiment of the present invention. It is a figure which shows the relationship between the increase in a drive current, and a black insertion rate. It is a figure which shows the display by the light emission area scroll method which always light-emits the image of 1 frame only to a certain ratio. It is a figure explaining the light extinction method and a drive waveform. It is a figure which shows the operation | movement waveform at the time of transfering from the standard mode (Standard Mode) to the moving image mode (Moving Picture Mode). It is explanatory drawing regarding the display method of the monochrome mode of the OLED display apparatus in this invention.

First, before describing specific embodiments, the gist of the present invention will be described as follows.
1. In the moving image mode, light emission and light extinction are performed in one frame so that driving can be performed without changing the driving frequency.
2. To convert from standard mode to video mode, set the extinction rate and video data adjustment coefficients (α, β),
a. Movie mode signal MPM (Moving Picture Mode),
b. Video data for video,
c. Pixel extinction start signal OFFST
Is generated by controlling light emission and extinction.
3. Conversion from the standard mode to the monochrome mode is performed by generating a monochrome mode signal MCM (MonoChrome Mode) and displaying a video signal of a material having the highest current-light conversion efficiency among self-luminous materials.
4). In the moving image mode, the luminance in the standard mode is controlled to a value inversely proportional to the turn-off rate.
5. The case where the MPM signal and the monochrome mode signal MCM are not generated is set as the standard mode.
6). Switching to each mode is open for direct user control.

  Here, the present invention provides a three-mode display device having a function capable of switching between a moving image mode, a standard mode, and a monochrome mode as a new function. FIG. 1 is a diagram showing an outline of a three-mode display device applied as an OLED display device according to the present invention. As shown in FIG. 1, the OLED display device according to the present invention has a function of switching between a moving image mode, a standard mode, and a monochrome mode.

Further, an outline of the OLED display device according to the present invention will be described below.
(1) In the data hold type OLED driving method, moving image blur tends to occur, and smooth moving image display has a drawback. To cope with this, the drive frequency was increased and black data was inserted. However, the increase in the drive frequency promotes the deterioration of the OLED material due to the increase in the power consumption and the increase in the current density. It was. Therefore, by turning on and off the light in one frame and flowing a current that matches the turn-off rate, a moving image display that can reduce moving image blur without changing the brightness, that is, without increasing power consumption, is achieved. Enable (this is called the Emission Scroll method). For this reason, it is not necessary to change the drive frequency in the standard mode.
(2) However, although the drive frequency is not changed, there is an extinguishing time, and in order to keep the luminance constant, it is necessary to increase the luminance in inverse proportion to the extinguishing time. For this reason, the current density which flows into OLED increases, and the problem that the degradation rate of OLED material increases generate | occur | produces. In order to reduce this, a selectable function of using the moving image mode only when necessary is added to the standard mode.
(3) Most portable devices are battery-driven, and low power consumption is essential. Although the user uses the battery while paying attention to the remaining battery level, there are situations where the user must continue to use the battery even when the remaining battery level is low. Therefore, if there is an effective function that can extend the usage time of the portable device, it is very effective for the user, and it is desired to reduce the power consumption of the display device as much as possible. The display device expresses a desired color by causing each color to emit light with a desired luminance based on the three primary colors of RGB. When there is no remaining battery power, it is sufficient to know the minimum information for operating the mobile device, so it is considered that there is no problem even if the three primary colors are set to one color. When reducing the display color to one color, in a self-luminous device such as an OLED, it is more effective for reducing power consumption to select a color having the highest current-light conversion efficiency. Green G is optimal, including the viewpoint of visibility. Furthermore, the monochrome mode does not input black data from the drive IC, but supplies power to the data line from the power supply prepared in the panel, so that the extra power consumption of the drive IC can be eliminated and the power consumption is further reduced. Electricity can be achieved. Also, by always using the monochrome mode, energy saving and battery charging opportunities can be reduced, and the effectiveness increases.
By providing such three modes that can be selected from the moving image mode, the standard mode, and the monochrome mode, it is possible to provide the user with unprecedented merit in use.

  Next, specific embodiments of the present invention will be described. FIG. 2 illustrates an OLED display device according to an embodiment of the present invention, and is a block diagram illustrating a function of a driving IC as a driving circuit for driving a display panel. The OLED display device shown in FIG. 2 has three driving modes: a moving image mode in which a smooth moving image can be enjoyed, a standard mode that can suppress the shortening of the life of the OLED material, and a monochrome mode that is a low power consumption mode. A three-mode OLED display device provided with switching means is shown, which is composed of a drive IC 10, a turn-off rate setting circuit 20, and a display panel 30. The standard mode is a mode in which the image quality is set to a bit rate around 4.6 Mbps.

  The driving IC 10 includes a logic circuit 11 having a configuration similar to the conventional one, a memory 14 for storing video data RGB, a DAC 16 for serial-parallel conversion of the video signal RGB, and a driver 17 as well as a mode switching means for video data A video data adjustment coefficient circuit 12 and a gamma adjustment coefficient circuit 13 for changing the calculation coefficient are provided with a turn-off start signal generator 15 for turning off the light and changing the drive control within one frame, and a monochrome mode signal. A monochrome mode signal supply line for supplying the MCM to the logic circuit 11, the memory 14, the DAC 16, the driver 17 and the display panel 30 to operate the logic circuit 11, the memory 14, the DAC 16, the driver 17 and the display panel 30 in the monochrome mode. It has.

  In the OLED display device shown in FIG. 2, the transition from the standard mode to the moving image mode is activated by the generation of a moving image mode signal (MPM signal, MPM: Moving Picture Mode). Generated based on the type of display data (moving image, still image, text, etc.) or a signal resulting from the type of application. When the MPM signal is activated, the video data adjustment coefficient circuit 12 changes the video data adjustment coefficient from the standard specification value (Standard) to the moving image mode value α. Similarly, in the gamma adjustment coefficient circuit 13, the gamma coefficient is changed from the standard specification value (Standard) to the moving image mode value β. In the logic circuit 11, video data is calculated based on the adjustment coefficient α from the video data adjustment coefficient circuit 12 and the adjustment coefficient β from the gamma adjustment coefficient circuit 13.

  The turn-off rate setting circuit 20 generates a turn-off time setting signal (TOFF signal) based on the turn-off rate δ, and the turn-off start signal generator 15 generates a turn-off start signal (TOFF signal) based on the turn-off time setting signal (TOFF signal). OFFST signal) is generated, and the extinction start signal (OFFST signal) has a function of activating a circuit for sequentially extinguishing the pixels. The turn-off rate setting circuit 20 and the turn-off start signal generator 15 may be created outside the drive IC 10 or may be created in the logic circuit 11 in the drive IC 10. The adjustment coefficients α and β are coefficients determined by determining the extinction rate δ.

  Next, the transition to the monochrome mode is activated by generation of a monochrome mode signal MCM (MonoChrome Mode) signal. The monochrome mode signal MCM is generated by a user instruction or a signal from the battery remaining amount monitoring system. When the monochrome mode signal MCM is activated, an operation of only the selected mono color is performed between the logic circuit 11 and the memory 14, and then a driver signal (CLK) required for the monochrome mode is sent from the driver 17 or the DAC 16. , X, Y drive signal, Mux signal, monochrome mode signal MCM) and video data are input to the panel 30.

  In the logic circuit 11, usually, arithmetic processing for various corrections is performed on the video data RGB. In the monochrome mode, calculation is performed only for one selected color. The calculation amount is reduced to one third or less, and the exchange of data between the memories 14 is also reduced. The driver 17 normally outputs a signal for writing video data of three colors. However, in the monochrome mode, only a signal necessary for writing one selected color is output. The DAC 16 normally outputs video data of three colors, but in the monochrome mode, only one selected color is output.

Next, details will be described below as the correspondence between the panel 30 and the input signals.
Moving picture mode
(A) Measures against moving image blur Measures against moving image blur by controlling the black insertion time in one frame without changing the drive frequency.
FIG. 3 is a diagram showing the relationship between the increase in drive current and the black insertion rate, where (a) shows the relationship between brightness and black insertion rate, and (b) shows the movement of the operating point when the drive current is multiplied several times. Show. If the set luminance is kept constant, the light emission time is shortened when the drive current is increased. For example, as shown in FIG.
In the case of black insertion 50% (point A → point B): twice the luminance and 50% light emission time.
In the case of 75% black insertion (point A → point C): 4 times the brightness and 25% light emission time.
Thus, as the light emission time becomes shorter, the input video voltage moves in a direction in which Vgs becomes larger.

Here, for example, black insertion 50% has the same meaning as the turn-off rate δ = 50%. That is, the brightness in the video mode is
Brightness in movie mode = Brightness in standard mode x (100 / light-off rate)
By controlling the luminance in the standard mode to a value inversely proportional to the extinction rate, it is possible to take a moving image blur countermeasure by controlling the black insertion time in one frame without changing the drive frequency.

(B) Video data when shifting from the standard mode to the moving image mode The drive current of the drive transistor Tr in the saturation region is expressed by the following equation.
I _DS = W / L · μ · C _ox · 1/2 · (V _GS −V _th ) ² (1)
Where W is the channel width, L is the channel length, μ is the mobility,
C _ox is the gate capacitance per unit area,
V _GS represents a gate-source voltage, and V _th represents a threshold voltage.
In the present invention, since black insertion is performed, the light emission time is shortened and the luminance is lowered. In order to keep the peak luminance in the standard mode and the luminance in the moving image mode constant, it is necessary to increase the driving current to increase the peak luminance. From equation (1), the parameter that can be changed by software is the gate-source voltage V _GS . In order to increase the gate-source voltage, the video data Vsig and Gamma are multiplied by adjustment coefficients α and β as follows.
・ Vsig = Vsig × α ・ Gamma = Gamma × β
Unlike the standard mode conversion coefficients, α and β are adjustment coefficients for normal display (brightness, gradation, etc.) in the moving image mode, and are constants influenced by the turn-off rate.

(C) Black data insertion method and display method (Emission Scroll method)
In the conventional black data insertion method, the driving frequency is increased. This indicates that the power consumption increases as the driving speed increases, and is not a good method. FIG. 4 shows a display by the light emitting area scroll method, which is a method of always emitting a certain frame of light at a certain rate. As shown in FIG. 4, one frame is divided into five screens, and the black insertion rate in each screen is set to 50%, and the 50% light emitting area is scrolled from top to bottom sequentially. Is done. In this way, moving image blur can be suppressed without increasing the drive frequency.

(D) Black data creation method (Emission Scroll method)
As a method for creating black data, a method for stopping light emission and turning it off is selected.
FIGS. 5A and 5B illustrate a light-off method and drive waveforms. FIG. 5A shows a light-off pixel circuit in the display panel 30 and FIG. 5B shows a drive line waveform. The extinguishing method is performed by turning off the driving transistor Tr2 in the pixel with one shot pulse within a period of 1V.
In this method, as shown in FIG. 5A, a stop transistor Tr off that stops a drive transistor Tr 2 that supplies current to an organic light emitting diode as a light emitting element, and a stop connected to the gate of the stop transistor Tr off An OFF shift register is required as a signal line drive circuit for driving the drive signal line OFF Line and the stop drive signal line OFF Line.

(E) Operation Waveform in Moving Picture Mode (MPM) FIG. 6 shows an operation waveform when shifting from the standard mode (Standard Mode) to the moving picture mode (Moving Picture Mode). When the recognition signal MPM indicating that the moving image mode is entered is activated (“L” in the figure), the OFF shift register is activated. In FIG. 6, VST represents a vertical period start signal, VOUT1 represents a vertical period end signal, and VOUT2 represents a light extinction period end signal.

Monochrome mode
(1) Features of the monochrome mode The points of the present invention regarding the monochrome mode are as follows.
a. Generating a monochrome mode signal MCM instructing monochrome mode display;
b. Write black data to the data line by the monochrome mode signal MCM.
c. The operation of the operation unnecessary circuit in the driving IC 10 is stopped by the monochrome mode signal MCM.
d. The monochrome mode is a mode that can be operated by a manufacturer's selection, a customer instruction, or a signal from the battery remaining amount monitoring system, and is a selectable function.
e. There are the following methods for writing black data to the data line.
A method of writing black data from the drive IC 10 as usual A method of writing a black potential existing in the panel 30 to a data line f. In the case of RGB, the monochrome mode color is effective for the color having the highest conversion efficiency, and in the case of RGB, the color is W (white).
g. The reduction of power consumption by the monochrome mode is a mode that is impossible for an LCD, and is a mode that can be more effective for RGBW pixels.
h. In the monochrome mode, the power consumption of the driving IC 10 as well as the panel 30 can be reduced.
i. 90% or more of the power consumption in the panel 30 portion is the power consumption in the OLED, and can be reduced to one third or less by the present invention.
j. With the monochrome mode, life-saving measures can be taken when the battery level is low, and emergency situations can be handled.

(2) Specific Circuit Example A method for introducing black data from the power supply inside the panel 30 is shown. This is a case where the OLED driving TFT in the pixel is p-ch Tr.
7A and 7B are explanatory diagrams relating to the monochrome mode display method of the OLED display device according to the present invention, in which FIG. 7A shows a data line drive circuit, and FIG. 7B shows a drive waveform in the monochrome mode. The OLED display device shown in FIG. 7 exemplifies a case where the G sub-pixel is set to a monochrome mode color as an appropriate one of the three primary colors RGB.

  In the configuration shown in FIG. 7, black data is generated using the monochrome mode signal MCM inside the panel 30 side. More specifically, a monochrome switch transistor MSW (Monochrome SW) is provided between the RGB data lines and the VDD line as a switch for switching to the monochrome mode.

When the monochrome mode signal MCM is “L” (that is, when mono color display is desired), the following operation is performed.
1) The Mux signals corresponding to R and B are received from the driving IC 10 as being fixed to “H”, and the number of operating is reduced to one of the G sub-pixels.
2) In the data lines R and B, when the monochrome switch transistor MSW is turned on, "H" data is input from the VDD line, and thereafter, there is no data change as long as the monochrome mode continues.
3) As a result, the R and B video data are “Don't care” and need not be driven by the driving IC 10.
As a result, black data can be written on the data line corresponding to the unselected sub-pixel on the panel 30 side, and the calculation load on the drive IC 10 side can be reduced.
Similarly, in the case of RGBW, only W-only video data has to be processed, and the power consumption is ¼ or less.

  Next, the operation on the drive IC 10 side will be described with reference to FIG. When the monochrome mode signal MCM is generated, the operation of only the selected mono color is performed between the logic circuit 11 and the memory 14, and then the driver 17 and the DAC 16 send the drive signals (CLK, X,. Y drive signal, Mux signal, monochrome mode signal MCM) and video data are input to the panel 30.

  The logic circuit 11 normally performs arithmetic processing for various corrections on R, G, and B video data. On the other hand, in the monochrome mode, calculation is performed for only one selected color. Accordingly, the calculation amount is reduced to one third or less, and the exchange of data with the memory 14 is also reduced.

  The driver 17 normally outputs a Mux signal for writing video data of three colors (R, G, B). However, in the monochrome mode, only the Mux signal necessary to write one selected color is output, and the other two colors are output as the “H” state.

  The DAC 16 normally outputs video data of three colors, but in the monochrome mode, only one selected color is output and reflected on the data line. On the other hand, for the other colors, the Mux signal is in the “H” state and the R and B data line drivers are in the OFF state (see FIGS. 7A and 7B). It doesn't matter if it's out. As a result, the calculation load on the drive IC 10 side can be reduced.

  Accordingly, it is possible to obtain an OLED display device having a configuration capable of selectively switching to the monochrome mode and switching the display mode to the monochrome mode as necessary, thereby reducing power consumption and extending the battery life. Can do.

  Further, by providing a configuration capable of switching to monochrome mode not only on the driver IC side but also on the panel side, the data lines corresponding to the sub-pixels that do not perform monocolor display are forced to have black data (that is, Data that does not emit light from the OLED), and arithmetic processing on the drive IC side can be reduced. That is, on the driving IC side, only one type of video data transfer (input / output) can be performed, and only one video data operation can be performed, thereby further reducing power consumption on the driving IC side.

As described above, according to the above embodiment, the following functions can be provided by providing three driving methods with one display device.
・ How to watch video without blurring ・ How to use for long life of OLED ・ How to use with low power consumption

Further, since the drive frequency is not changed between the drive modes, the following can be expected.
-Low power consumption drive can be realized without a large increase in power consumption.
-The design burden is light, and development costs are reduced and product development is easy.

Furthermore, the following can be expected by opening the mode switching to the user (or set maker).
-Power consumption can be finely managed by the user (or set maker) according to the remaining battery level, drive mode, and application.
・ Various options can be offered to the panel user.

Claims (4)

In an OLED display device using an organic light emitting diode as a light emitting element,
The drive circuit for driving the display panel is provided with mode switching means for switching the mode from the standard mode, the moving image mode, and the monochrome mode based on the input of the moving image mode signal and the monochrome mode signal to be shifted from the standard mode to the moving image mode .
In the monochrome mode, data is supplied from the driving IC to one color sub-pixel among a plurality of sub-pixels constituting each pixel, and the remaining color sub-pixels among the plurality of sub-pixels of each pixel An OLED display device, wherein a black potential existing inside a display panel is supplied to a corresponding data line without supplying data from the driving IC . The OLED display device according to claim 1,
The mode switching means includes a video data adjustment counting circuit and a gamma adjustment counting circuit for changing a calculation coefficient of video data based on an input of a moving image mode signal, and a drive control change by turning off the light within one frame. A turn-off start signal generator for performing, and a monochrome mode signal supply line for supplying a monochrome mode signal to the constituent circuits in the drive circuit and the display panel,
The moving image mode is activated when the moving image mode signal is input to the drive circuit, and a pixel turn-off start signal from the turn-off start signal generator is input to the display panel,
The monochrome mode is activated when the monochrome mode signal is input to the drive circuit and the display panel,
The OLED display device, wherein the standard mode is activated in a state where the moving image mode signal and the monochrome mode signal are not generated. The OLED display device according to claim 2,
The display panel includes a stop transistor that stops a drive transistor that supplies current to the light emitting element, a stop drive signal line connected to a gate of the stop transistor, and a signal line that drives the stop drive signal line An OLED display device comprising: a driving circuit for driving; and a switch circuit for receiving the black- and-white mode signal and supplying the black potential to a data line. In the OLED display device according to any one of claims 1 to 3,
The driving in the standard mode, the moving image mode, and the monochrome mode is switched based on a user instruction, a type of display data, a type of application used by the display device , and a signal resulting from a remaining battery level. OLED display device.

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