KR101255290B1 - Organic Light Emitting Diode Display device - Google Patents

Abstract

The present invention relates to an OLED display device that can switch between three display modes of a video mode, a standard mode, and a black and white mode by a simple method without a large increase in power consumption. The present invention relates to an OLED display device using an organic light emitting diode as a light emitting device. A mode switching means for performing mode switching of a standard mode, a video mode, and a black and white mode based on input of a video mode signal and a black and white mode signal to a driving IC for driving a display panel from a standard mode to a video mode, A video data adjustment coefficient circuit and a gamma adjustment coefficient circuit for changing the calculation coefficient of the video data in response to the input of the video mode signal, and an unlit start signal for changing the drive control by performing an unlit driving in one frame. And a generator, and at the same time, a monochrome mode signal in the driving circuit and the display panel And a black-and-white mode signal supply line for supplying to the.

Description

Organic Light Emitting Diode Display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OLED (Organic Light Emitting Diode) display device using an organic light emitting diode as a light emitting device. In particular, the present invention realizes low-power video display and long life while reducing power consumption. The present invention relates to an OLED display device.

In the prior art, as a display device that prevents the state of moving images and increases the power consumption and extends the lifespan of the moving image, the display device controls the black color in the case of moving images by the value of the identification signal for recognizing whether the input data is moving images or still images. Insertion drive is performed, and black images are not inserted in the case of a still image. In the case of black insertion, one frame is divided into the front and rear subfields, the image is displayed in the previous field, and the following ( Vi) Black insertion is carried out in a field (for example, refer patent document 1).

In addition, since the OLED display is a self-luminous type, when the background portion is displayed in white and the character portion is displayed in black, the power consumption is lower than when the background portion is displayed in black and the character portion is displayed in white. The display is inverted to achieve low power consumption (see Patent Document 2, for example).

Patent Document 1 Japanese Unexamined Patent Publication No. 2007-114286

Patent Document 2: Japanese Unexamined Patent Publication No. 2003-108076

However, since OLED is the same data hold type as LCD, it is easy to produce a video blur and has a drawback in smooth video display.

In order to solve this problem, black data is inserted by increasing the driving frequency. However, increasing the driving frequency becomes a problem of promoting acceleration of deterioration of OLED materials due to an increase in power consumption or an increase in current density.

In addition, in order to prevent a moving image, there is a light-off time, so in order to keep the brightness constant, it is necessary to increase the brightness in inverse proportion to the light-off time.

For this reason, the problem that the current density which flows through OLED increases, and the degradation rate of OLED material increases.

In addition, since most of the portable devices are battery-powered, lower power consumption is essential. The user is using it while paying attention to the battery level, but there is a situation in which the user must continue to use even when the battery level is low.

Therefore, if there is an effective function that can increase the use time of the portable device, it is a very effective means for the user, and it is desirable that the power of the display device can be minimized.

The present invention has been devised to solve the above problems, and consumes three display modes: a video mode for enjoying video, a standard mode for controlling short life of OLED materials, and a black and white mode suitable for a self-luminous display device. It is an object of the present invention to provide an OLED display which realizes a switchable function in a simple manner without greatly increasing the power.

The OLED display device according to the present invention for achieving the above object is in the OLED display device using an organic light emitting diode as a light emitting device, the moving picture mode signal for transitioning from the standard mode to the video mode to the drive circuit for driving the display panel and And mode switching means for changing modes of the standard mode, the moving picture mode, and the black and white mode according to the input of the black and white mode signal, wherein the mode switching means changes the calculation coefficient of the video data according to the input of the moving picture mode signal. A video data adjustment coefficient circuit and a gamma adjustment coefficient circuit, a lighting start signal generator for changing the driving control for lighting lighting in one frame, and a black and white mode signal to the driving circuit in the driving circuit and the display panel. And a black and white mode signal supply line, wherein the video mode is the moving picture. A mode signal is input to the driving circuit, and a pixel lighting start signal is activated from the lighting start signal generator to be input to the display panel, and the monochrome mode is such that the monochrome mode signal is input to the driving circuit and the display panel. And the standard mode is activated in a state where the video mode signal and the black and white mode signal do not occur.

According to the OLED display device according to the present invention, the following effects are obtained.

That is, according to the purpose, the video mode, standard mode, and black-and-white mode can be divided into a video display without dullness, long life, and low power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing an outline of a three mode display device applied as an OLED display device according to the present invention.
2 is a block diagram illustrating a function of a driving IC, illustrating an OLED display according to the present invention.
3A and 3B are graphs showing a relationship between an increase in driving current and a black insertion rate;
4 is a view showing a display using a light emitting area scrolling method in which a video of one frame is emitted by a corresponding ratio;
5A and 5B are diagrams for explaining the extinction method and the driving waveform.
Fig. 6 is a view showing an operating waveform when transitioning from the standard mode to the video mode.
7A and 7B are explanatory views of a display method of a black and white mode of an OLED display according to the present invention.

Hereinafter, an OLED display according to the present invention will be described in detail with reference to the accompanying drawings.

First, before describing the OLED display of the present invention, what is needed in the present invention will be described.

1. In the moving picture mode, the light is turned on and off in one frame so that the drive can be performed without changing the driving frequency.

2. In the conversion from the standard mode to the video mode, after setting the extinction rate and the adjustment coefficients (α, β) of the video data,

a. Moving picture mode signal MPM (Moving Picture Mode),

b. Video data for video,

c. The pixel off start signal OFFSET is generated and light emission and light off are controlled.

3. Switching from the standard mode to the monochrome mode is performed by generating the monochrome mode signal MCM (Monochrome Mode) and displaying the video signal of the material having the most current-light conversion efficiency among the self-luminous materials.

4. In video mode, the brightness in standard mode is controlled in inverse proportion to the extinction rate.

5. The video mode signal MPM and the black and white mode signal MCM do not occur.

6. Switching to each mode is open for direct user control.

Here, the present invention provides a three-mode display device having a function of switching between a video mode, a standard mode, and a black and white mode as a new function.

1 is a view 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 according to the present invention has a function of switching between a video mode, a standard mode, and a black and white mode.

Moreover, the outline | summary of OLED display device by this invention is demonstrated below.

(1) The OLED driving method of the data holder type tends to cause a video blur, and has a drawback in displaying a smooth video.

In order to solve this problem, black data is inserted by increasing the driving frequency. However, increasing the driving frequency promotes acceleration of degradation of OLED materials due to an increase in power consumption or an increase in current density.

Therefore, light emission and extinguishing are performed within one frame, and a current is flowed in accordance with the extinction rate so that video display can be reduced without changing the brightness, for example, without reducing the power consumption. It is called the Emission Scroll method). This does not require changing the drive frequency in standard mode.

(2) However, it is necessary to increase the luminance in inverse proportion to the extinction time in order to keep the luminance constant since there is an extinction time for not changing the driving frequency. This increases the current density flowing to the OLED, which increases the rate of degradation of the OLED material.

To alleviate this, we add a feature to standard mode that lets you select the video mode only when needed.

(3) In addition, most of portable devices are battery driven, and low power consumption is essential. The user is using it while paying attention to the battery level, but there is a situation that the user must continue to use even when the battery level is low. Therefore, if there is a valid function that can extend the use time of the portable device is very effective for the user, it is desirable to make the power consumption of the display device extremely small.

The display device expresses a desired color by emitting three primary colors of RGB at a desired luminance. If there is no battery level, the minimum information can be divided in the state of operating the mobile device, so it is not a problem even if the three primary colors are one color.

When changing the display color to one color, in a self-luminous device such as an OLED, selecting the color having the largest current-light conversion efficiency is more effective for lowering power consumption. Green (G) is optimal including the viewpoint of visibility.

In addition, the black and white mode does not input black data from the driver IC, but supplies the data line from the power supply used in the panel, thereby excluding the extra power consumption of the driver IC and further reducing the power consumption. In addition, the use of black and white mode at all times reduces the opportunity for energy saving and battery charging, increasing the effectiveness.

Providing three selectable modes, such as a video mode, a standard mode, and a black and white mode, can provide a user with an advantage that has not been available until now.

Next, specific embodiment of this invention is described.

Fig. 2 illustrates an OLED display device according to an embodiment of the present invention, which is a block diagram showing the function of a drive IC as a drive circuit for driving a display panel.

The OLED display shown in FIG. 2 is provided with a mode switching means of three driving modes: a video mode for viewing a smooth video, a standard mode capable of controlling long life of the OLED material, and a black and white mode, which is a low power consumption mode. A three-mode OLED display device is shown, and is composed of a driving IC 10, an extinction rate setting circuit 20, and a display panel 30.

On the other hand, the standard mode refers to a mode in which the image quality is set at a bit rate of around 4.6 Mbps.

The driving IC 10 is a video as mode switching means in addition to the logic circuit 11, the memory 14 storing the video data RGB, the DAC 16 and the driver 16 for serial-to-parallel conversion of the video signal RGB. The video data adjustment coefficient circuit 12 and the gamma adjustment coefficient circuit 13 to change the calculation coefficient of the data, and the light-off start signal generator 15 for changing the drive control for turning off the light within one frame. In addition, the monochrome mode signal MCM is supplied to the logic circuit 11, the memory 14, the DAC 16, the driver 17, and the display panel 30 to supply the logic circuit 11 and the memory. (14), a black and white mode signal supply line for operating the DAC 16, the driver 17, and the display panel 30 in the black and white mode is provided.

In the OLED display shown in Fig. 2, the transition from the standard mode to the moving picture mode is started by the generation of the moving picture mode signal (MPM signal), which is an instruction from the user and the type of display data (video, still image). Image, text, etc.) or a signal due to the type of application. When the MPM signal is activated, the video data adjustment coefficient 12 is changed from the value of the standard mode to the value α of the video mode.

Likewise, in the gamma adjustment coefficient circuit 13, the gamma coefficient is changed from the standard mode value to the value?. In the logic circuit 11, video data is calculated based on the adjustment coefficient? From the video data adjustment coefficient circuit 12 and the adjustment coefficient β from the gamma adjustment coefficient circuit 13.

Further, the extinction rate setting circuit 20 generates an extinction time setting signal (TOFF signal) in accordance with the extinguishing rate δ, and the extinguishing start signal generator 15 extinguishes the extinguishing start signal in accordance with the extinguishing time setting signal (TOFF signal). (OFFST signal) is generated, and the light-off start signal (OFFST signal) has a function of activating a circuit for turning off the pixels in sequence.

The extinction rate setting circuit 20 and the extinguishing start signal generator 15 may be configured outside the driving IC 10 or in the logic circuit 11 inside the driving IC 10. In addition, the adjustment coefficients (alpha), (beta) are coefficients by which the extinction ratio (delta) is decided.

Subsequently, the transition to the black and white mode is started by the generation of the black and white mode signal (MCM signal). The black-and-white mode signal MCM is generated by a user's instruction or a signal from a battery level monitoring system.

When the monochrome mode signal MCM is activated, only the selected mono-color operation is performed between the logic circuit 11 and the memory 14, and then the drive signal CLK necessary for the monochrome mode from the driver 17 or the DAC 16 is performed. , X, Y driving signals, Mux signals, monochrome mode signals (MCM)) or video data are input to the panel 30.

In the logic circuit 11, arithmetic processing is usually performed for various corrections of the video data RGB. In black and white mode, only one color is selected. The amount of calculation is reduced to less than one third, and the data between the memories 14 is also reduced. The driver 17 normally outputs a signal for writing video data of three colors.

However, in black and white mode, only the signal for the selected one color light is output. In addition, video data of three colors is normally output from the DAC 16, but only one selected color is output from the black and white mode.

Next, the panel 30 and the corresponding input signals will be described in detail below.

Moving Picture Mode

(a) Countermeasures in the state of vacancy

The black insertion time in one frame is controlled without changing the driving frequency to take a countermeasure against a state of blur.

3A and 3B are diagrams showing a relationship between an increase in driving current and a black insertion rate, and FIG. 3A shows a relationship between luminance and a black insertion rate, and FIG. 3B shows a movement of an operating point when the driving current is several times. . If the set luminance is kept constant, the driving current is increased and the light emission time is shortened.

For example, as shown in Figs. 3A and 3B, in the case of black insertion 50% (point A to point B): the luminance was doubled and the emission time was 50%. In the case of black insertion 75% (point A to point C): the luminance is four times and the light emission time is 25%, and as the light emission time is shortened, the input video voltage moves in a direction in which Vgs becomes larger.

Here, for example, black insertion 50% means the same as extinction ratio (delta) = 50%. That is, the luminance in the video mode is given by the following equation, and the luminance in the video mode = luminance in the standard mode × (100 / light extinction rate) and the luminance in the standard mode are controlled by a value inversely proportional to the extinction rate. By controlling the black insertion time in one frame without changing the frequency, it is possible to take a countermeasure against a state of blur.

(b) Video data when moving from standard mode to video mode

The driving current of the driving transistor Tr in the saturation region is represented by Equation 1 below.

Where W is channel width, L is channel length, μ is mobility, Cox is gate capacitance per unit area, V _GS is gate-to-source voltage, and Vth is threshold voltage.

In the present invention, since black insertion is performed, the light emission time is shortened, and the luminance decreases. When the peak luminance in the standard mode and the luminance in the video mode are held constant, it is necessary to increase the driving current to increase the peak luminance. The software-variable parameter from Equation 1 is the gate-to-source voltage V _GS . In order to make the gate-source voltage larger, the adjustment coefficients α and β are inserted into the video data Vsig and Gamma as follows.

 ? and? are different from the conversion coefficients in the standard mode, and are adjustment coefficients for performing normal display (luminance, gradation, etc.) in the moving picture mode, and are constants affected by the extinction 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 due to the higher speed of the drive, which is not a good method.

Fig. 4 shows a method of emitting one frame of video by a certain magnification, and shows the display by scrolling the light emitting area.

As shown in Fig. 4, one frame is divided into five screens, and the black insertion rate in each screen is set to 50%. The light emitting area of 50% is displayed by scrolling sequentially from top to bottom. In this way, it is possible to control the state of video blur without increasing the driving frequency.

(d) Method of creating black data (Emission Scroll method)

As a method of creating black data, a method of stopping light emission and turning off the light is selected.

5A and 5B illustrate the extinguishing method and the driving waveform. FIG. 5A shows the unlit pixel circuit in the display panel 30, and FIG. 5B shows the driving line waveform. The extinguishing method is performed by turning off the driving transistor (Tr) 2 in the pixel with one short pulse in the 1V period.

In this method, as shown in Fig. 5A, the stop drive signal Tr off for stopping the drive transistor 2 for supplying current to the organic light emitting diode as a light emitting element, and the stop drive signal connected to the gates of the stop transistor Tr off. An OFF shift register is required as a driving circuit for signal lines for driving an OFF line and an OFF driving signal line.

(e) Operation waveform in video mode (MPM)

Fig. 6 shows the operation waveform when the transition from the standard mode to the dynamic mode. The OFF shift register is activated by activating the recognition signal MPM, which means the moving image mode ("L" in the figure). 6, VST indicates a vertical synchronization start signal, VOUT1 indicates a vertical period end signal, and VOUT2 indicates an unlit period end signal.

Monochrome mode

(1) Features of black and white mode

The points of the present invention with respect to the monochrome mode are as follows.

a. Generating a monochrome mode signal (MCM) indicating monochrome mode indication.

b. The black data is written to the data line by the monochrome mode signal MCM.

c. Stopping the operation of the circuit in which the operation is unnecessary in the driving IC 10 by the monochrome mode signal MCM.

d. The black and white mode is a mode that can be operated by a manufacturer's selection, an audience's instruction, or a signal from a battery level monitoring system.

e. As a method of writing black data on a data line, there are conventional methods of writing black data from the driver IC 10 and a method of writing black potential existing in the panel 30 to the data line.

f. In the case of RGB, the color having the highest conversion efficiency is effective for RGB, and W (white) for RGB.

g. The low power consumption by the black and white mode is a mode that is impossible for LCD, and a mode that can be more effective with RGBW pixels.

h. In the black and white mode, not only the panel 30 portion but also the power consumption of the driving IC 10 can be reduced.

i. More than 90% of the power consumption in the panel 30 portion is power consumption in the OLED, and can be made less than one third by the present invention.

j. With the black-and-white mode, it is possible to extend the life when the battery level decreases and respond to emergencies.

(2) concrete circuit example

The method of introducing black data from the power supply of the panel 30 part is shown. This is the case where the OLED driving TFT is set to p-ch Tr in the pixel.

7A and 7B are explanatory views of the display method of the black and white mode in the OLED display device of the present invention. FIG. 7A shows the driving circuit of the data line, and FIG. 7B shows the driving waveform in the black and white mode. The OLED display shown in Figs. 7A and 7B exemplifies a case where the G sub-pixel is a color in black and white mode as one of the three primary colors of RGB.

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

When the monochrome mode signal MCM is " L " (that is, when the monochromatic display is to be performed), the following operation is performed.

1) Receiving and operating the Mux signals corresponding to R and B from the driver IC 10 with " H " fixed is reduced to one of the G sub pixels.

2) As for the data lines of R and B, when the monochrome switch transistor MSW is ON, "H" data is input from the VDD line and thereafter, there is no change of data as long as the monochrome mode continues.

3) As a result, the video data of R and B becomes "Don't care" and does not need to be driven by the drive IC 10.

As a result, black data can be written from the panel 30 side to the data line corresponding to the unselected sub-pixels, and the computation load on the driver IC 10 side can be reduced.

Similarly, in the case of RGBW, only video data of W may be processed, and power consumption is less than one quarter.

Next, the operation on the driver IC 10 side will be described with reference to FIG. 1. When the black-and-white mode signal MCM occurs, the operation of the selected mono-color only operation is performed between the logic circuit 11 and the memory 14, and then the drive signal required for the black-and-white mode from the driver 17 and the DAC 16 ( CLK, X, Y drive signal, Mux signal, monochrome mode signal (MCM)) and video data are input to the panel 30.

The logic circuit 11 usually performs arithmetic processing for various corrections on the video data of R, G, and B. On the other hand, in black and white mode, calculation is performed only for one selected color. Therefore, the amount of calculation is reduced to less than one third, so that the exchange of data with the memory 14 is also reduced.

In addition, the driver 17 normally outputs a Mux signal for writing three-color (R, G, B) video data. However, in the black and white mode, only the Mux signal necessary for writing one selected color is output, and the other two colors are output as the "H" state.

In addition, three-color video data is normally output from the DAC 16, but only one selected color is output from the black and white mode to be reflected on the data line.

On the other hand, since 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), any data can be used as the video data. As a result, the computational load on the driver IC 10 side can be reduced.

Therefore, an OLED display device having a configuration capable of selective switching to a black and white mode, and switching the display mode to a black and white mode as required, can achieve low power consumption and a longer battery life.

In addition, by having a configuration capable of selective conversion to monochrome mode not only on the driver IC 10 side but also on the panel 30 side, black data (i.e., Data that the OLED does not emit light) can be reduced to reduce the arithmetic processing on the driver IC 10 side.

In other words, on the driving IC 10 side, only one type of video data transmission (input and output) can be performed, and only one video data operation can be performed, further reducing power consumption on the driving IC side. can do.

As mentioned above, according to the said embodiment, the following functions can be provided by providing three drive methods with one display apparatus.

In other words, it is possible to watch a video image without any bleak state, to prolong the life of OLED and to reduce the power consumption.

In addition, since the driving frequency is not changed between the respective driving modes, the following can be expected.

That is, there is no large increase in power consumption, low power consumption driving can be realized, and the design burden is reduced, so that development costs can be reduced and product development is easy.

Moreover, the following can be expected by opening the conversion of each mode to the user (or set maker).

That is, the power consumption can be managed by the user (or set maker) in detail according to the remaining battery level, the driving mode, the application, and the like, and various options can be provided to the side using the panel.

10: drive IC 11: logic circuit
12: video data adjustment coefficient circuit 13: gamma adjustment coefficient circuit
14 memory 15 light start signal generator
16: DAC 17: Driver
20: extinction rate setting circuit 30: display panel

Claims (4)

In an OLED display using an organic light emitting diode as a light emitting element,
A driving circuit for driving the display panel;
And a mode switching means for performing mode switching between standard mode, video mode, and black and white mode in accordance with input of a video mode signal and a black and white mode signal for transitioning from the standard mode to the video mode.
The mode switching means
A video data adjustment coefficient circuit and a gamma adjustment coefficient circuit for changing the calculation coefficient of the video data in response to the input of the video mode signal;
An unlit start signal generator for changing the drive control which performs unlit driving in one frame;
And a black and white mode signal supply line for supplying the black and white mode signal to the driving circuit and the display panel.
The display panel includes a black and white switching transistor connected to two data lines selected from among RGB data lines and a VDD line to supply the voltage provided from the VDD line to the selected two data lines as black data when the monochrome mode signal is supplied. and,
The moving picture mode is activated by inputting the moving picture mode signal to the driving circuit and inputting the pixel off start signal to the display panel from the turn off start signal generator,
The monochrome mode is activated by inputting the monochrome mode signal into the driving circuit and the display panel.
And the standard mode is activated in a state where the video mode signal and the black and white mode signal do not occur. delete The display panel of claim 1, wherein the display panel
And a stop transistor for stopping the drive transistor for supplying current to the light emitting element, a stop drive signal line connected to the gate of the stop transistor, and a signal line drive circuit for driving the stop drive signal line. OLED display. The method of claim 1, wherein the driving of the standard mode, the moving picture mode, and the black and white mode is switched according to an instruction from a user, a type of display data, a signal resulting from a type of application using a display device, and a battery level monitoring system. OLED display, characterized in that.

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