KR101354325B1 - Organic Light Emitting Diode Display And Driving Method Thereof - Google Patents

Abstract

The present invention relates to an organic light emitting diode display device and a method of driving the same which adjust RGB gamma reference voltages according to color coordinates according to brightness of an input image.

According to an embodiment of the present invention, an organic light emitting diode display for driving an organic light emitting diode using gamma reference voltages between a high potential power voltage and a low potential power voltage includes a plurality of first organic light emitting diodes emitting red light; A display panel including a plurality of second organic light emitting diodes emitting green light and a plurality of third organic light emitting diodes emitting blue light, wherein the plurality of data lines and the plurality of gate lines cross each other; A first lookup table for selecting first digital data for adjusting each of the first gamma reference voltages for driving the first organic light emitting diode; A first digital-analog converter that selects voltages corresponding to the first digital data and outputs a plurality of first gamma reference voltages; A second lookup table for selecting second digital data for adjusting each of the gamma reference voltages of the second organic light emitting diode; A second digital-analog converter that selects voltages corresponding to the second digital data and outputs a plurality of second gamma reference voltages; A third lookup table for selecting third digital data for adjusting each of gamma reference voltages of the third organic light emitting diode; And a third digital-analog converter that selects voltages corresponding to the third digital data and outputs a plurality of third gamma reference voltages.

Description

Organic Light Emitting Diode Display And Driving Method Thereof

1 is a diagram illustrating a light emitting principle of a conventional organic light emitting diode display.

2 is a diagram illustrating adjusting a gamma reference voltage according to brightness of an input image to reduce display load.

3A to 3C are diagrams illustrating an example of adjusting the gamma reference voltage upward by R, G, and B. FIG.

4 is a block diagram of an organic light emitting diode display according to an exemplary embodiment of the present invention.

5A through 5C are circuit diagrams illustrating an example of the pixel illustrated in FIG. 4.

FIG. 6 is a detailed block diagram of the gamma reference voltage controller shown in FIG. 4. FIG.

FIG. 7 is a diagram illustrating a gamma reference voltage generator shown in FIG. 4. FIG.

8A to 8C show changes in gamma curve for each RGB after application of the present invention.

Description of the Related Art

110: high potential power voltage supply terminal 112: low potential power voltage supply terminal

120: organic light emitting diode display panel 122: gate driver

124: data driver 126: gamma reference voltage generator

128: sub-pixel 128-2: pixel driver circuit

30: timing control unit 132: gamma reference voltage control unit

32-2: luminance detector 132-4: adder

32-6: Average value calculation unit 132-8: Storage unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode display and a driving method thereof, and more particularly, to an organic light emitting diode display and a method of driving the RGB gamma reference voltages according to brightness of an input image.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. Such flat panel displays include liquid crystal displays (hereinafter referred to as "LCDs"), field emission displays (FEDs), plasma display panels (hereinafter referred to as "PDPs"). And organic light emitting diode displays.

Among these PDPs, PDPs are attracting attention as a display device that is most advantageous for large screen size but large screen size because of simple structure and manufacturing process, but it has disadvantage of low luminous efficiency, low luminance and high power consumption. In addition, an active matrix LCD having a thin film transistor (“TFT”) applied as a switching device has a disadvantage in that large screens are difficult to use due to a semiconductor process and power consumption is large due to a backlight unit.

In contrast, organic light emitting diode display devices are classified into inorganic light emitting diode display devices and organic light emitting diode display devices according to the material of the light emitting layer. The organic light emitting diode display devices are self-luminous devices that emit light and have high response speed, high luminous efficiency, high luminance, and a wide viewing angle. . In comparison with the organic light emitting diode display, the inorganic light emitting diode display has higher power consumption and cannot obtain high brightness, and cannot emit various colors of R (Red), G (Green), and B (Blue). On the other hand, the organic light emitting diode display is driven at a low DC voltage of several tens of volts, has a fast response speed, obtains high luminance, and emits various colors of R, G, and B, which is suitable for next-generation flat panel display devices. Do. The organic light emitting diode display includes an organic light emitting diode element in each of the pixels arranged in a matrix form.

1 is a diagram illustrating a light emitting principle of a general organic light emitting diode device. Referring to FIG. 1, when a voltage is applied between the anode 100 and the cathode 70 of the organic light emitting diode device, electrons generated from the cathode 70 are transferred through the electron injection layer 78a and the electron transport layer 78b. It is moved toward the organic light emitting layer 78c. Holes generated from the anode 100 move toward the organic light emitting layer 78c through the hole injection layer 78e and the hole transport layer 78d. Accordingly, in the organic light emitting layer 78c, light is generated by collision and recombination of electrons and holes supplied from the electron transport layer 78b and the hole transport layer 78d, and the light is emitted to the outside through the anode 100. The image is displayed.

On the other hand, the organic light emitting diode display has a property that is vulnerable to temperature. The temperature of the organic light emitting diode display increases as the display load increases, which is an important factor in determining the lifetime and display quality of the organic light emitting diode device. In general, the display load is larger when a bright image is implemented than when a dark image is implemented. Therefore, recently, a method of reducing the display load by adjusting the gamma reference voltage according to the brightness of the input image has been proposed.

2 shows that the gamma reference voltage is adjusted according to the brightness of the input image to reduce the display load.

Accordingly, the brightness information of the input image is analyzed so that when there is only a partially bright image as shown in FIG. 2A, since the display load is small, the highest gamma reference voltage is adjusted upward so as to produce peak luminance. On the other hand, when there is an overall bright image as shown in (b) of FIG. 2, since the display load is large, the uppermost gamma reference voltage is adjusted downward to decrease the luminance, thereby reducing the burden of the organic light emitting diode device. The highest gamma reference voltage is adjusted up or down by adjusting the power supply voltage to generate gamma reference voltages.

However, according to the brightness of the input image, the highest gamma reference voltage is uniformly adjusted up or down irrespective of the R, G, and B pixels, which is a major factor causing color distortion.

3A to 3C are diagrams illustrating examples of adjusting the gamma reference voltage upward by R, G, and B. FIG. 3A to 3C, the horizontal axis represents gray scale and the vertical axis represents luminance.

In the organic light emitting diode display device, the red organic light emitting diode device constituting the R subpixel, the green organic light emitting diode device constituting the G subpixel, and the blue organic light emitting diode device constituting the B subpixel each emit light with respect to a current. Since the capability, that is, the light efficiency, is different, the R, G, and B subpixels display an image with data voltages generated by gamma reference voltages independent of each other. Here, the gamma reference voltages adjusted according to the upward adjustment of the highest gamma reference voltage should be differentially controlled so as to reflect the difference in light efficiency for each of R, G, and B. Actually, as shown in FIGS. It is just a uniform upward adjustment along the voltage.

Therefore, when the peak luminance is realized or the display load is reduced by adjusting the conventional highest gamma reference voltage, a difference occurs between an ideal gamma curve for each of R, G, and B that matches color coordinates, and a gamma curve implemented through actual adjustment. As a result, there is a problem that the color balance is broken and the display quality is lowered.

In addition, in the case of realizing peak luminance or reducing the display load by adjusting the conventional highest gamma reference voltage, the conventional R, G, and B subpixels may display images by data voltages generated by using gamma reference voltages that are independent of each other. Since it is displayed, it is very difficult to adjust the gamma curve accurately matched to the color coordinates, which causes a problem that the gamma curve adjustment takes a long time.

Accordingly, an object of the present invention is to provide an organic light emitting diode display device and a method of driving the RGB gamma reference voltages that can be adjusted to match color coordinates according to brightness of an input image.

Another object of the present invention is to provide an organic light emitting diode display and a method of driving the same, which allow the RGB gamma reference voltages to be easily adjusted according to the brightness of an input image.

In order to achieve the above object, according to an embodiment of the present invention, an organic light emitting diode display for driving an organic light emitting diode using gamma reference voltages between a high potential power voltage and a low potential power voltage may include a plurality of light emitting red light. A display panel including a first organic light emitting diode, a plurality of second organic light emitting diodes emitting green light, and a plurality of third organic light emitting diodes emitting blue light, wherein the plurality of data lines and the plurality of gate lines cross each other; A first lookup table for selecting first digital data for adjusting each of the first gamma reference voltages for driving the first organic light emitting diode; A first digital-analog converter that selects voltages corresponding to the first digital data and outputs a plurality of first gamma reference voltages; A second lookup table for selecting second digital data for adjusting each of the gamma reference voltages of the second organic light emitting diode; A second digital-analog converter that selects voltages corresponding to the second digital data and outputs a plurality of second gamma reference voltages; A third lookup table for selecting third digital data for adjusting each of gamma reference voltages of the third organic light emitting diode; And a third digital-analog converter that selects voltages corresponding to the third digital data and outputs a plurality of third gamma reference voltages.

And an average value calculator for calculating average luminance of RGB digital data to be displayed on the display panel during one frame period.

The first to third lookup tables select the first to third digital data, respectively, corresponding to the average luminance.

Digital data listed in each of the first to third lookup tables is determined in a direction in which the gamma reference voltages are lowered as the average brightness is higher.

The digital data listed in each of the first to third lookup tables is determined in a direction in which the gamma reference voltages are increased as the average luminance is lower.

In order to achieve the above object, according to an embodiment of the present invention, a plurality of first organic light emitting diodes emitting red light, a plurality of second organic light emitting diodes emitting green light, and a plurality of third organic light emitting blue lights An organic light emitting diode display device including a light emitting diode and driving the organic light emitting diodes of a display panel where a plurality of data lines and a plurality of gate lines cross each other using gamma reference voltages between a high potential power voltage and a low potential power voltage. The driving method may include selecting the first digital data from a first lookup table including first digital data for adjusting each of the first gamma reference voltages for driving the first organic light emitting diode; Selecting the voltages corresponding to the first digital data to generate the first gamma reference voltages; Selecting the second digital data from a second lookup table including second digital data for adjusting each of the second gamma reference voltages for driving the second organic light emitting diode; Selecting voltages corresponding to the second digital data to generate the second gamma reference voltages; Selecting the third digital data from a third lookup table including third digital data for adjusting each of the third gamma reference voltages for driving the third organic light emitting diode; And selecting the voltages corresponding to the third digital data to generate the third gamma reference voltages.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 8C.

4 is a configuration diagram of an organic light emitting diode display according to an exemplary embodiment of the present invention, and FIGS. 5A to 5C are circuit diagrams illustrating an example of the pixel illustrated in FIG. 4.

Referring to FIG. 4, an organic light emitting diode display according to an exemplary embodiment of the present invention includes R and G arranged in regions defined by intersections of a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm. And an organic light emitting diode display panel 120 including B subpixels 128, a gate driver 122 supplying scan pulses to gate lines GL1 to GLn of the organic light emitting diode display panel 120. The timing for controlling the driving timing of the data driver 124, the gate driver 122, and the data driver 124 to supply analog data voltages to the data lines DL1 to DLm of the organic light emitting diode display panel 120. A gamma reference voltage controller 132 for controlling the voltage levels of the R, G, and B gamma reference voltages RGMA, GGMA, and BGMA to be changed according to color coordinates according to the brightness of the input image; Data under control of the controller 132 A gamma reference voltage generator 126 for generating a plurality of R, G, and B gamma reference voltages RGMA, GGMA, and BGMA supplied to the driver 124 is provided.

Sub-pixels 128 are arranged in a matrix in the organic light emitting diode display panel 120. The organic light emitting diode display panel 120 includes a high potential power supply voltage supply terminal 110 that receives a high potential driving voltage VDD from the driving voltage generator 134, and a base voltage from a base voltage source (not shown). The low potential power voltage supply terminal 112 supplied with (VSS) is provided. The high potential driving voltage VDD supplied to the high potential power voltage supply terminal 110 and the base voltage VSS supplied to the low potential power voltage supply terminal 112 are supplied to the respective subpixels 128. Each of the subpixels 128 receives an analog data voltage from the data line DL when the gate signal is supplied to the gate line GL, and generates light corresponding to the data voltage. Each of the subpixels 128 may include any one of R, G, and B organic light emitting diodes. R subpixel 128R has an R organic light emitting diode, G subpixel 128G has a G organic light emitting diode, and B subpixel 128B has a B organic light emitting diode. The color implementation for one pixel consists of a combination of these three subpixels. The R subpixel 128R having the R organic light emitting diode OLED-R has an anode electrode connected to a high potential power voltage supply terminal 110 that supplies a high potential driving voltage VDD as shown in FIG. 5A. The low potential power supply voltage terminal 112 and the R organic light emitting diode (OLED-R), which are connected to the gate line GL and the data line DL and supply a ground voltage VSS. And a pixel driver circuit 128-2 connected to the cathode electrode of the OLED-R for driving the R organic light emitting diode OLED-R. The pixel driver circuit 128-2 includes a switching thin film transistor having a gate electrode connected to the gate line GL, a drain electrode connected to the data line DL, and a source electrode connected to the node N. TFT " (ST), a gate electrode at node N, a drain electrode at cathode electrode of R organic light emitting diode (OLED-R), and a source electrode at low potential power supply voltage 112. A connected driving TFT DT, and a storage capacitor Cst connected between the cathode electrode of the R organic light emitting diode OLED-R and the node N are provided. During the scan period, the switching TFT ST is turned on in response to the scan pulse supplied to the gate line GL to supply the node N with the analog data voltage supplied to the data line DL. The analog data voltage supplied to the node N is charged to the storage capacitor Cst and supplied to the gate electrode of the driving TFT DT. The driving TFT DT is turned on in response to the analog data voltage supplied to the gate electrode to control the amount of driving current I flowing through the R organic light emitting diode OLED-R, thereby controlling the R organic light emitting diode OLED-R. The amount of light emitted is adjusted. During the non-scan period, even when the switching TFT ST is turned off, the driving TFT DT is discharged due to the discharge of the analog data voltage stored in the storage capacitor Cst until the analog data voltage of the next frame is supplied. The light emission of the organic light emitting diode OLED-R is maintained. Pixel 128G having G organic light emitting diode (OLED-G) and pixel 128B having B organic light emitting diode (OLED-B) are as shown in FIGS. 5B and 5C, respectively. Since their functions and functions are substantially the same as those of the pixel 128R having the above-described R organic light emitting diode OLED-R, detailed description thereof will be omitted. The pixel driver circuit 128-2 may be replaced with various structures in addition to the above-described structure.

The timing controller 130 controls the data control signal DDC and the gate driver 122 to control the data driver 124 using the vertical and horizontal synchronization signals HV Sync and the input dot clock DCLK. The gate control signal GDC is generated. The data control signal DDC includes a source shift clock SSC, a source start pulse SSP and a source output enable signal SOE, and the gate control signal GDC includes a gate start pulse GSP and A gate output enable signal GOE and the like. The data control signal DDC generated by the timing controller 130 is supplied to the data driver 124 to control the data driver 124. The gate control signal GDC generated by the timing controller 130 is supplied to the gate driver 122 to control the gate driver 122. In addition, the timing controller 130 rearranges the digital video data RGB supplied from the scaler (not shown) and supplies the digital video data RGB to the data driver 124 and the gamma reference voltage controller 132.

The gate driver 122 turns off the gate high voltage and the switching TFT in the subpixel 128 to turn on the switching TFT in the subpixel 128 in response to the gate control signal GDC from the timing controller 130. Generates a scan pulse swinging between the gate low voltages. The gate driver 122 supplies the generated scan pulses to the gate lines GL1 to GLn to sequentially drive the gate lines GL1 to GLn.

The gamma reference voltage controller 132 detects luminance values of each subpixel 128 using the input digital video data RGB and calculates a maximum luminance value of each subpixel 128 among the detected luminance values. do. The gamma reference voltage controller 132 adds all the calculated maximum luminance values of the sub-pixels 128 and then calculates the average luminance of the current frame by using the added values. The gamma reference voltage controller 132 reads the R gamma reference voltage control data, the G gamma reference voltage control data, and the B gamma reference voltage control data stored in the lookup table, using the calculated average luminance data of the current frame as the read address. To the gamma reference voltage generator 126. The RGB gamma reference voltage control data are control data for varying the voltage level of the RGB gamma reference voltages according to the color coordinates according to the average luminance of the input digital video data RGB. The gamma reference voltage controller 132 may be built in the timing controller 130. The gamma reference voltage controller 132 will be described in detail with reference to FIG. 6.

The gamma reference voltage generator 126 generates a plurality of R gamma reference voltages, a plurality of G gamma reference voltages, and a plurality of B gamma reference voltages in response to the control data from the gamma reference voltage controller 132. To this end, the gamma reference voltage generator 126 may include a digital-to-analog converter for generating a plurality of R gamma reference voltages, a digital-to-analog converter for generating a plurality of G gamma reference voltages, and a plurality of B gamma reference voltages. Digital-to-analog converter for generation. The gamma reference voltage generator 126 will be described in detail with reference to FIG. 7.

The data driver 124 generates a plurality of R, G, and B gamma voltages by dividing the R, G, and B gamma reference voltages from the gamma reference voltage generator 126 by gray levels. These multiple gamma voltages are voltages at which the gamma reference voltages between the high potential supply voltage and the low potential supply voltage are subdivided by the plurality of voltage divider resistors. The data driver 124 converts the digital video data RGB input in response to the data control signal DDC from the timing controller 130 into R, G, and B analog data voltages using R, G, and B gamma voltages. Convert. The data driver 124 supplies the converted analog data voltages to the data lines DL1 to DLm in synchronization with the timing at which the scan pulses are supplied.

FIG. 6 is a detailed block diagram of the gamma reference voltage controller 132 shown in FIG. 4.

Referring to FIG. 6, the gamma reference voltage controller 132 according to an exemplary embodiment of the present invention detects luminance values of each sub-pixel 128 by using digital video data RGB of an input current frame. Among the luminance values, both the luminance detector 132-2 for calculating the maximum luminance value of each subpixel 128 and the maximum luminance value of each subpixel 128 detected by the luminance detector 132-2 Calculation of an average value for calculating the average luminance data Avi (br) of the current frame using the addition unit 132-4 for adding and the addition value of the maximum luminance values added by the adding unit 132-4. A plurality of R, G, and B gamma reference voltage control data CR1 selected by using the unit 132-6 and the average luminance data Avi (br) from the average value calculator 132-6 as the lead address. And a storage unit 132-8 for storing CR8, CG1 to CG8, and CB1 to CB8.

The luminance detector 132-2 analyzes the gradation levels of the digital video data RGB of the current frame input from the system for each subpixel 128 and then uses the gradation levels of the analyzed digital video data RGB. Detect the RGB luminance values of each pixel. When the RGB luminance value is detected in this way, the luminance detector 132-2 calculates the maximum luminance value among the RGB luminance values of each subpixel 128, and adds the calculated maximum luminance value of each subpixel 128. Output to (132-4).

The adder 132-4 adds all the maximum luminance values of each sub-pixel 128 detected by the luminance detector 132-2, and outputs the added value of the maximum luminance values to the average value calculator 132-6. do.

The average value calculator 132-6 divides the sum of the maximum luminance values input from the adder 132-4 into a predetermined resolution, and divides the quotient into the average luminance of the current frame (that is, the average luminance of each sub-pixel). The calculated average luminance data Avi (br) is output to the storage unit 132-8.

The storage unit 132-8 stores a plurality of R, G, and B gamma reference voltage control data CR1 ˜ selected from the average luminance data Avi (br) from the average value calculator 132-6 as a read address. CR8, CG1 to CG8, CB1 to CB8) are stored. The storage unit 132-8 stores the first lookup table LUT1 and the average luminance data Avi for selecting the R gamma reference voltage control data CR1 to CR8 according to the average luminance data Avi (br). br) gamma reference voltage control data CB1 according to the second lookup table LUT2 for selecting the G gamma reference voltage control data CG1 to CG8 and the average luminance data Avi (br). And a third lookup table LUT3 for selecting CB8). The first to third lookup tables LUT1 to LUT3 may be implemented as a nonvolatile memory capable of updating and erasing data, for example, an electrically erasable programmable read only memory (EEPROM) and / or an extended display identification data ROM (EDID ROM). do. The control data may be updated by an electrical signal applied from the outside through a user interface (not shown). In this way, the user can easily adjust the RGB gamma reference voltages, thereby greatly reducing the time required to adjust the gamma curve. On the other hand, the number of control data corresponding to each of the average luminance listed in the first to third lookup tables (LUT1 to LUT3) is only one embodiment, and the average luminance according to the number of gamma reference voltages to be adjusted The number of control data corresponding to each is variable.

Eight R gamma reference voltage control data corresponding to each of a plurality of average luminance data serving as read addresses are listed in the first lookup table LUT1. The control data listed in the first lookup table LUT1 is determined to lower the R gamma reference voltages as the average luminance data Avi (br) is higher, and as the average luminance data Avi (br) is lower, the R gamma reference. It is determined to raise the voltages. In particular, these control data are experimentally predetermined values with color coordinates optimized for the average luminance in consideration of driving characteristics of R organic light emitting diodes, panel characteristics according to resolution and panel size, and the like.

Eight G gamma reference voltage control data corresponding to each of a plurality of average luminance data serving as read addresses are listed in the second lookup table LUT2. The control data listed in the second lookup table LUT2 is determined to lower the G gamma reference voltages as the average luminance data Avi (br) is higher, and as the average luminance data Avi (br) is lower, the G gamma reference. It is determined to raise the voltages. In particular, these control data are experimentally predetermined values in which color coordinates are optimized for each average luminance in consideration of driving characteristics of the G organic light emitting diode, panel characteristics according to resolution or panel size, and the like.

Eight B gamma reference voltage control data corresponding to each of a plurality of average luminance data serving as read addresses are listed in the third lookup table LUT3. The control data listed in the third lookup table LUT3 is determined to lower B gamma reference voltages as the average luminance data Avi (br) is higher, and as the average luminance data Avi (br) is lower, the B gamma reference. It is determined to raise the voltages. In particular, these control data are experimentally predetermined values with color coordinates optimized for each average luminance in consideration of driving characteristics of B organic light emitting diodes, panel characteristics according to resolution and panel size, and the like.

FIG. 7 is a diagram illustrating a gamma reference voltage generator shown in FIG. 4.

Referring to FIG. 7, the gamma reference voltage generator 126 may include an R gamma reference voltage generator 126R for outputting a plurality of R gamma reference voltages RGMA1 to RGMA8 in response to the R gamma reference voltage control data. G gamma reference voltage generator 126G for outputting a plurality of G gamma reference voltages GGGMA1 to GGMA8 in response to the G gamma reference voltage control data, and a plurality of B gamma references in response to the B gamma reference voltage control data. A B gamma reference voltage generator 126B for outputting the voltages BGMA1 to BGMA8 is provided.

The R gamma reference voltage generator 126R is implemented as a first digital-to-analog converter DAC1. The first digital-to-analog converter DAC1 includes a plurality of switch elements that are switched in response to the R gamma reference voltage control data. The plurality of switch elements may be composed of N-type transistors, or may be composed of P-type transistors. The first digital-to-analog converter DAC1 switches a plurality of switch elements in response to each of the eight R gamma reference voltage control data, thereby converting eight of the input voltages Vs1 to Vsn to the R gamma reference voltages RGMA1 to. RGMA8). The output R gamma reference voltages RGMA1 to RGMA8 have voltage values at which color coordinates are optimized according to the average luminance of the current frame.

The G gamma reference voltage generator 126G is implemented as a second digital-to-analog converter DAC2. The second digital-to-analog converter DAC2 includes a plurality of switch elements that are switched in response to the G gamma reference voltage control data. The plurality of switch elements may be composed of N-type transistors, or may be composed of P-type transistors. The second digital-to-analog converter DAC2 switches a plurality of switch elements in response to each of the eight G gamma reference voltage control data, thereby converting eight of the input voltages Vs1 to Vsn to the G gamma reference voltages GGGMA1 to. Output to GGMA8). The output G gamma reference voltages GGMA1 to GGMA8 have voltage values at which color coordinates are optimized according to the average luminance of the current frame.

The B gamma reference voltage generator 126B is implemented with a third digital-to-analog converter DAC3. The third digital-to-analog converter DAC3 includes a plurality of switch elements that are switched in response to the B gamma reference voltage control data. The plurality of switch elements may be composed of N-type transistors, or may be composed of P-type transistors. The third digital-to-analog converter DAC3 switches a plurality of switch elements in response to each of the eight B gamma reference voltage control data, thereby converting eight of the input voltages Vs1 to Vsn to the B gamma reference voltages BGMA1 to. BGMA8). The output B gamma reference voltages BGMA1 to BGMA8 have voltage values at which color coordinates are optimized according to the average luminance of the current frame.

8A to 8C are diagrams showing the change of the gamma curve for each RGB after application of the present invention. In FIG. 8A to FIG. 8C, the horizontal axis represents gray scale and the vertical axis represents luminance (cd / m 2). The curve following Δ is a default gamma curve before application of the present invention, and the curve following s is According to the present invention, a gamma curve after upward adjustment of gamma reference voltages is shown.

FIG. 8A shows an R gamma curve, FIG. 8B shows a G gamma curve, and FIG. 8C shows a B gamma curve. As shown in FIG. It does not increase and increases gradually. 8A to 8C, the present invention can easily and accurately match color coordinates by generating differential gamma reference voltages for each RGB to reflect the light efficiency difference for each RGB, using control data of the lookup table.

As described above, the organic light emitting diode display and the driving method thereof according to the present invention use the control data that are experimentally determined to be the value of the color coordinate optimized for each of the average luminance calculated in consideration of driving characteristics, panel characteristics, and the like. By generating gamma reference voltages for each RGB, gamma reference voltages for each RGB may be adjusted to match color coordinates.

Furthermore, the organic light emitting diode display and the driving method thereof according to the present invention are gamma-by-RGB gamma using control data that are experimentally predetermined as color coordinates optimized for each average luminance calculated by considering driving characteristics and panel characteristics. By adjusting the reference voltages to match the color coordinates, it is easy to adjust the RGB gamma reference voltages, which can greatly reduce the time required for adjusting the gamma curve.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. For example, in the embodiment of the present invention, the number of control data corresponding to each of the average luminance of the lookup table is described as eight, but this is variable according to the number of generated gamma reference voltages, and the technical concept of the present invention is not limited thereto. Do not. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims (10)

An organic light emitting diode display device which drives an organic light emitting diode using gamma reference voltages between a high potential power voltage and a low potential power voltage. A plurality of first organic light emitting diodes emitting red light, a plurality of second organic light emitting diodes emitting green light, a plurality of third organic light emitting diodes emitting blue light, and a plurality of data lines and a plurality of gate lines Display panels intersecting each other; A first lookup table for selecting first digital data for adjusting each of the first gamma reference voltages for driving the first organic light emitting diode; A first digital-analog converter that selects voltages corresponding to the first digital data and outputs a plurality of first gamma reference voltages; A second lookup table for selecting second digital data for adjusting each of the gamma reference voltages of the second organic light emitting diode; A second digital-analog converter that selects voltages corresponding to the second digital data and outputs a plurality of second gamma reference voltages; A third lookup table for selecting third digital data for adjusting each of gamma reference voltages of the third organic light emitting diode; And A third digital-analog converter configured to select voltages corresponding to the third digital data and output a plurality of third gamma reference voltages; And an average value calculator for calculating average luminance of the RGB digital data to be displayed on the display panel for one frame period. And the first to third lookup tables select the first to third digital data corresponding to the average luminance, respectively. delete delete The method of claim 1, And the digital data listed in each of the first to third lookup tables is determined in a direction of decreasing the gamma reference voltages as the average brightness is higher. The method of claim 1, And the digital data listed in each of the first to third lookup tables is determined in a direction of increasing the gamma reference voltages as the average luminance is lower. A plurality of first organic light emitting diodes emitting red light, a plurality of second organic light emitting diodes emitting green light, a plurality of third organic light emitting diodes emitting blue light, and a plurality of data lines and a plurality of gate lines A method of driving an organic light emitting diode display device in which the organic light emitting diodes of the display panel are crossed using gamma reference voltages between a high potential power voltage and a low potential power voltage. Selecting the first digital data from a first lookup table including first digital data for adjusting each of the first gamma reference voltages for driving the first organic light emitting diode; Selecting the voltages corresponding to the first digital data to generate the first gamma reference voltages; Selecting the second digital data from a second lookup table including second digital data for adjusting each of the second gamma reference voltages for driving the second organic light emitting diode; Selecting voltages corresponding to the second digital data to generate the second gamma reference voltages; Selecting the third digital data from a third lookup table including third digital data for adjusting each of the third gamma reference voltages for driving the third organic light emitting diode; And Selecting the voltages corresponding to the third digital data to generate the third gamma reference voltages; Calculating an average luminance of the RGB digital data to be displayed on the display panel for one frame period, And the first, second, and third lookup tables select the first, second, and third digital data corresponding to the average luminance, respectively. delete delete The method of claim 6, The digital data listed in each of the first to third lookup tables is determined in a direction in which the gamma reference voltages are lowered as the average brightness is higher. The method of claim 6, The digital data listed in each of the first to third lookup tables is determined in a direction in which the gamma reference voltages are increased as the average brightness is lower.

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