KR20150075605A - Organic light emitting display device and method for driving thereof - Google Patents

Abstract

An organic light-emitting display device including a white sub-pixel according to an aspect of the present invention can prevent a color coordinate change and afterimage caused by degradation of a white organic light-emitting device, and comprises: a display panel including a plurality of unit pixels consisting of red, green, blue, and white sub-pixels having organic light-emitting devices; a 4-color data converting unit for converting red, green, and blue input data into red, green, blue, and white input data by using a first lookup table (LUT); a degradation compensating unit for generating red, green, blue, and white output data by reflecting a particular gain value to the red, green, blue, and white input data, accumulating and storing the red, green, blue, and white output data in every set accumulation period, calculating a color ratio value of red, green, and blue colors according to the accumulated white output data, and feeding back the same to the 4-color data converting unit; and a panel driving unit for outputting a particular image through the display panel by supplying the red, green, blue, and white output data to a corresponding sub-pixel. The 4-color data converting unit renews the first lookup table based on the fed back color ratio value so that a color temperature of the white sub-pixel can become a target color temperature.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting diode (OLED) display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display including a white sub-pixel.

Recently, with the development of multimedia, the importance of flat panel display devices is increasing. In response to this, flat panel display devices such as liquid crystal display devices, plasma display devices, and organic light emitting display devices have been commercialized. Of these flat panel display devices, the organic light emitting display device has a high response speed and has self-luminescence, so there is no problem in the viewing angle, and has been attracting attention as a next generation flat panel display device.

A general organic light emitting display device includes sub-pixels of red (R), green (G), and blue (B) as one unit pixel (Unit Pixel) As shown in FIG.

Recently, a four-color organic light emitting display device in which white (W) sub-pixels are added to a unit pixel to increase the luminance of a unit pixel has been developed. In such a four-color organic light emitting display, three-color input data of red, green, and blue are converted into four-color data of red, green, blue, and white and displayed.

In the conventional four-color organic light emitting diode display, when white color driving is performed, white sub-pixels are always emitted, while two sub-pixels among red, green, and blue sub-pixels are selectively emitted to emit a desired white color . At this time, the red, green, blue, and white output data are recorded on a lookup table (LUT) for each of the red, green, and blue input data and the target color temperature.

The above-described conventional four-color organic light emitting display device is proposed under the assumption that the color coordinates of the white sub-pixels are uniform. However, since the white organic light emitting device included in the white sub-pixel actually emits light at all times unlike the other sub-pixels, the organic light emitting device can be deteriorated relatively faster than other sub-pixels depending on the material properties and the light emission time. Degradation causes white luminance drop and color coordinate change.

Therefore, in the conventional four-color organic light emitting diode display, yellowish phenomenon occurs due to the shift of the color coordinates (CIEx, CIEy) according to the deterioration of the white organic light emitting device, and such a change in color coordinates is seen as a residual image .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an organic light emitting diode (OLED) display device and a method of driving the same, which can prevent a color coordinate change and an afterimage due to deterioration of a white organic light emitting diode The present invention has been made in view of the above problems.

According to an aspect of the present invention, there is provided an organic light emitting diode display comprising: a display panel including a plurality of unit pixels including red, green, blue, and white sub-pixels having organic light emitting elements; A four-color data converter for converting red, green, and blue input data into red, green, blue, and white input data using a first lookup table (LUT); Green, blue, and white output data by reflecting a predetermined gain value to the red, green, blue, and white input data, and outputting the red, green, A deterioration compensation unit for calculating the three color ratio values of red, green, and blue according to the accumulated white output data and feeding back the calculated three color ratio values to the four-color data conversion unit; And a panel driver for supplying the red, green, blue, and white output data to the corresponding sub-pixel and outputting a predetermined image through the display panel, wherein the four-color data converter converts the color temperature of the white sub- And the first lookup table is updated based on the fed-back three-color ratio value so that the target color temperature becomes the target color temperature.

According to another aspect of the present invention, there is provided a method of driving an organic light emitting display including a unit pixel including red, green, blue, and white sub-pixels having organic light emitting elements, The method comprising: converting red, green, and blue input data into red, green, blue, and white input data using a first lookup table; Generating red, green, blue, and white output data by reflecting a predetermined gain value on the red, green, blue, and white input data; And accumulating and storing the red, green, blue, and white output data in a memory for every set accumulation period; Calculating three color ratio values of red, green, and blue according to the accumulated white output data; And updating the first look-up table based on the calculated three-color ratio value so that a color temperature of the white sub-pixel becomes a target color temperature.

According to the present invention, the deterioration of the organic light emitting element can be compensated based on the cumulative data of each sub-pixel.

According to the present invention, the three color ratio values of red, green, and blue according to the cumulative data of white subpixels are fed back, and the three color input data is converted into four color input data based on the fed- The color temperature of the white sub-pixel can be corrected to be the target value, thereby preventing the color coordinate change and the yellowish phenomenon due to deterioration of the white organic light emitting device, There is an effect that a residual image can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining a configuration of an organic light emitting display according to an embodiment of the present invention; FIG.
2 is a circuit diagram showing the structure of a pixel circuit according to an embodiment of the present invention;
FIG. 3 is a block diagram schematically showing the configuration of a four-color data conversion unit in FIG. 2;
4 is a block diagram schematically showing the configuration of the deterioration compensator shown in FIG. 2. FIG.
5 is a graph for explaining a gain value calculation method according to the first embodiment of the present invention.
6 is a graph for explaining a gain value calculation method according to the second embodiment of the present invention;
7 is a graph for explaining a gain value calculation method according to the third embodiment of the present invention.
8 is a graph showing changes in color temperature before and after applying the color temperature correction technique according to the present invention.
9 is a flowchart illustrating a method of driving an organic light emitting display according to an exemplary embodiment of the present invention.
10 is a flowchart showing a first lookup table updating method shown in FIG.

The meaning of the terms described herein should be understood as follows.

The word " first, "" second," and the like, used to distinguish one element from another, are to be understood to include plural representations unless the context clearly dictates otherwise. The scope of the right should not be limited by these terms.

It should be understood that the terms "comprises" or "having" does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, Means any combination of items that can be presented from more than one.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a configuration of an organic light emitting diode display according to an embodiment of the present invention.

1, an OLED display according to an exemplary embodiment of the present invention includes a display panel 100, a four-color data converter 200, a deterioration compensator 250, a panel driver 300, 400).

The display panel 100 includes a plurality of unit pixels, and each unit pixel includes a plurality of sub pixels (SPs). The plurality of subpixels SP are formed in a pixel region defined by a plurality of gate lines GL and a plurality of data lines DL intersecting with each other. The display panel 100 is formed with a plurality of driving power lines PL1 that are arranged in parallel to the plurality of data lines DL and are supplied with the driving voltage from the panel driving unit 300. [

Each of the plurality of sub-pixels SP may be any one of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. One unit pixel for displaying one image may include an adjacent red subpixel, a green subpixel, a blue subpixel, and a white subpixel, or may include a red subpixel, a green subpixel, and a blue subpixel. Hereinafter, it is assumed that one unit pixel is composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel.

Each of the plurality of sub-pixels SP includes an organic light emitting element OLED and a pixel circuit PC.

The organic light emitting diode OLED is connected between the pixel circuit PC and the second driving power supply line PL2 and emits a predetermined color light by emitting light in proportion to the amount of data current supplied from the pixel circuit PC. To this end, the organic light emitting device OLED includes an anode electrode (or a pixel electrode) connected to the pixel circuit PC, a cathode electrode (or a reflective electrode) connected to the second driving power supply line PL2, And a light emitting cell formed between the electrodes and emitting light of any one of red, green, blue, and white. Here, the light emitting cell may have a structure of a hole transporting layer / an organic light emitting layer / an electron transporting layer or a structure of a hole injecting layer / a hole transporting layer / an organic light emitting layer / an electron transporting layer / an electron injecting layer. Furthermore, a functional layer for improving the luminous efficiency and / or lifetime of the organic light emitting layer may be additionally formed in the light emitting cell.

The pixel circuit PC supplies the data voltage DL from the panel driver 300 to the data line DL in response to the gate signal GS of the gate-on voltage level supplied from the panel driver 300 to the gate line GL Vdata) to the organic light emitting diode OLED. At this time, the data voltage Vdata has a voltage value in which the deterioration characteristic of the organic light emitting diode OLED is compensated. To this end, the pixel circuit PC comprises a switching transistor, a driving transistor, and at least one capacitor formed on a substrate by a thin film transistor forming process. Here, the switching transistor and the driving transistor may be an a-Si TFT, a poly-Si TFT, an oxide TFT, an organic TFT, or the like.

An example of such a pixel circuit PC is shown in Fig. Hereinafter, the configuration of the pixel circuit PC will be briefly described with reference to FIG.

2 is a circuit diagram showing a structure of a pixel circuit according to an embodiment of the present invention.

The switching transistor Tsw supplies the data voltage Vdata supplied to the data line DL to the gate electrode GL of the driving transistor Tdr in accordance with the gate signal GS of the gate- .

The driving transistor Tdr controls the data current Ioled flowing to the organic light emitting element OLED by being turned on according to the gate-source voltage including the data voltage Vdata supplied from the switching transistor Tsw.

The capacitor Cst is connected between the gate electrode and the source electrode of the driving transistor Tdr to charge the difference voltage between the gate and the source of the driving transistor Tdr and then switches the driving transistor Tdr according to the charged voltage.

The pixel circuit PC shown in Fig. 2 is only one example, and the number of transistors and capacitors constituting the pixel circuit PC may be variously modified.

Referring again to FIG. 1, the four-color data conversion unit 200 converts red, green, and blue based on a timing synchronization signal TSS input from an external system body (not shown) or a graphics card (not shown) Green and blue colors to be supplied to the red subpixel, the green subpixel, the blue subpixel and the white subpixel constituting one unit pixel based on the three-color input data (R, G, B) , And four-color input data Ri, Gi, Bi, Wi of white.

In one embodiment, the four-color data converter 200 converts red, green, and blue three-color input data R, G, and B into red, green, and blue using a first lookup table (LUT) Green, blue, and white four-color input data Ri, Gi, Bi, Wi.

In particular, when the degradation compensation unit 250 determines that the white sub-pixel is deteriorated, the four-color data conversion unit 200 according to the present invention may detect the white, And updates the first lookup table so that the color temperature of the white sub-pixel becomes the target color temperature based on the RGB three-color ratio value (RGB Portion).

That is, when it is determined that deterioration of the white sub-pixel occurs in the present invention, in the process of converting the three-color input data R, G, B into the four-color input data Ri, Gi, Bi, The color temperature of the white subpixel can be corrected so that the color temperature of the white subpixel becomes the target color temperature by adjusting the color ratio value, thereby preventing the afterimage due to the color coordinate change.

A more detailed description of the four-color data conversion unit 200 according to an embodiment of the present invention will be described later with reference to FIG.

The deterioration compensating unit 250 reflects a predetermined gain value to four color input data Ri, Gi, Bi, and Wi of red, green, blue, and white output from the four- Color output data (Ro, Go, Bo, Wo) of green, blue, and white.

In particular, the deterioration compensation unit 250 according to the present invention accumulates and stores the four-color output data (Ro, Go, Bo, Wo) of red, green, blue and white in the memory unit 400 every set accumulation period , And calculates the three color ratio values of red, green, and blue according to the accumulated white output data, and feeds back the result to the four-color data conversion unit 200.

A more detailed description of the deterioration compensating unit 250 according to an embodiment of the present invention will be described later with reference to FIG.

The panel driving unit 300 generates the gate control signal GCS and the data control signal DCS based on the timing synchronization signal TSS and generates the gate signal GS in accordance with the gate control signal GCS, And outputs the four color output data Ro, Go, Bo, and Wo supplied from the deterioration compensating unit 250 to the data voltage Vdata in accordance with the data control signal DCS, (DL). For this, the panel driver 300 includes a timing controller 320, a gate driver circuit 330, and a data driver circuit 340.

The timing controller 320 controls the timing of driving the gate driving circuit 330 and the data driving circuit 340 according to a timing synchronization signal TSS input from an external system body (not shown) or a graphic card (not shown) . That is, the timing controller 320 generates a gate control signal (TSS) based on a timing synchronization signal TSS such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, a dot clock DCLK, GCS and a data control signal DCS and controls the driving timing of the gate driving circuit part 330 through the gate control signal GCS and controls the data driving circuit part 340 As shown in Fig.

The timing control unit 320 outputs the four color output data Ro, Go, Bo, and Wo of red, green, blue, and white supplied from the deterioration compensating unit 250 to the pixel arrangement structure And supplies the aligned data (DATA) to the data driving circuit portion 340 based on a predetermined interface method.

Meanwhile, the timing controller 320 may include the deterioration compensator 250. In this case, the deterioration compensating unit 250 may be embedded in the timing control unit 320, and in this case, the deterioration compensating unit 250 may be embodied in a program form or a logic form.

The gate driving circuit unit 330 generates a gate signal GS corresponding to the display order of the image based on the gate control signal GCS supplied from the timing control unit 320 and supplies the generated gate signal GS to the corresponding gate line GL . The gate driving circuit unit 330 may be formed in the form of a plurality of integrated circuits or may be formed directly on the substrate of the display panel 100 together with the transistor forming process of each sub pixel SP, (GL), respectively.

The data driving circuit unit 340 receives the data DATA and the data control signal DCS from the timing controller 320 and receives a plurality of reference gamma voltages from an external reference gamma voltage supply unit. The data driving circuit 340 converts the alignment data DATA into an analog data voltage Vdata using a plurality of reference gamma voltages in accordance with the data control signal DCS, ) To the data line DL of the corresponding sub-pixel SP. As such, the data driving circuit portion 340 may be formed in a plurality of integrated circuits (ICs) and connected to one side and / or both sides of the data line DL.

Hereinafter, the configuration of the four-color data conversion unit shown in Fig. 2 will be described in more detail with reference to Fig.

3 is a block diagram schematically showing a configuration of a four-color data conversion unit according to an embodiment of the present invention.

3, the four-color data conversion unit 200 according to an exemplary embodiment of the present invention includes a data conversion unit 201, a comparison unit 202, a correction amount calculation unit 203, and a table update unit 204).

First, the data converting unit 201 converts the three-color input data (R, G, B) of red, green, and blue so that the color temperature of the white subpixel becomes the target color temperature by using the first lookup table 205, Into four color input data Ri, Gi, Bi, Wi of red, green, blue, and white.

In one embodiment, the first lookup table 205 records the target three color ratio values to be applied to the three color input data (R, G, and B) and the target color temperature of the white sub-pixel. According to this embodiment, the data conversion section 201 selects the target color ratio value matching the target color temperature of the white sub-pixel and the three-color input data (R, G, B) on the first lookup table 205 And generates the four-color input data Ri, Gi, Bi, Wi by applying the selected target color ratio value to the three-color input data R, G,

The comparator 202 receives a three-color ratio value fed back from the deterioration compensator 250 (hereinafter, referred to as a 'fed-back three-color ratio value'). The comparator 202 compares the three-color ratio value (hereinafter, referred to as 'target three-color ratio value'), which causes the color temperature of the white sub-pixel to be the target color temperature, with the fed three- .

The correction amount calculation unit 203 receives the deviation calculated by the comparison unit 202 from the comparison unit 202 and calculates the deviation calculated by the comparison unit 202 on the second lookup table 206 and the target color temperature And acquires the corresponding three-color ratio value correction amount. At this time, the second lookup table 206 records the target color temperature and the three-color ratio value correction amount to be applied to each deviation. Therefore, the correction amount calculating section 203 extracts the three-color ratio value correction amount matched to the deviation calculated by the comparing section 202 and the target color temperature on the second look-up table.

The table updating unit 204 receives the three-color ratio value correction amount from the correction amount calculating unit 203 and outputs the received three-color ratio value correction amount to the target three-color ratio Value and corrects the target three-color-ratio value to update the first look-up table.

In the embodiment described above, the table updating unit 204 corrects the target three-color ratio value by reflecting the three-color ratio value correction amount to the target three-color ratio value recorded in the first look-up table 205, 1 look-up table 205 is updated.

However, in another embodiment, the data conversion unit 201 does not include the separate table updating unit 204 and the three-color ratio value correction amount is added to the target three-color ratio value on the first look- (Ri, Gi, B) by selecting another target three-color ratio value having the same value as the reflected result value and applying the selected other target three-color ratio value to the three-color input data , Bi, Wi).

Hereinafter, the configuration of the deterioration compensator shown in FIG. 2 will be described in more detail with reference to FIG.

4 is a block diagram schematically illustrating a configuration of a deterioration compensator according to an embodiment of the present invention.

4, the deterioration compensating unit 250 according to an embodiment of the present invention includes a data compensating unit 410, a data accumulating unit 420, an address controlling unit 430, a gain value calculating unit 440, And an arithmetic unit 450.

The data compensating unit 410 receives the red image data, the green image data, the blue image data, and the white four-color input data Ri, Gi, Bi, Wi from the four- Or in parallel.

The data compensator 410 generates four-color output data Ro, Go, Bo, and Wo by reflecting a predetermined gain value to the received four-color input data Ri, Gi, Bi, and Wi.

In one embodiment, the data compensator 410 multiplies the four-color input data Ri, Gi, Bi, Wi of each sub-pixel by a predetermined gain value to generate four-color output data Ro, Go, Bo, Wo) can be generated.

At this time, the predetermined gain value may be generated by the gain value calculating unit 440 and stored in the memory unit 400. Accordingly, the data compensating unit 410 reads a predetermined gain value to be applied to the corresponding sub-pixel in the memory unit 400 and reflects the gain value to the four-color input data Ri, Gi, Bi, Wi of each sub-pixel.

In one embodiment, the predetermined gain value may be updated on a frame-by-frame basis. The predetermined gain value to be initially reflected on the four-color input data Ri, Gi, Bi, Wi of each sub-pixel may be predetermined or set to "1".

The data compensator 410 provides the generated four-color output data Ro, Go, Bo, and Wo to the panel driver 300, i.e., the timing controller 320 described above.

The data accumulating unit 420 accumulates the four color output data Ro, Go, Bo, and Wo output from the data compensating unit 410 to compensate for deterioration of the organic light emitting diode included in each sub- And accumulates them in the memory unit 400 every time.

That is, the data accumulation unit 420 accumulates the accumulated output data Adata of the corresponding sub-pixel SP corresponding to the output data Ro, Go, Bo, Wo of each sub-pixel from the memory unit 400, And the output data Ro, Go, Bo and Wo are accumulated again in the accumulated output data Adata of the read corresponding subpixel SP and stored in the memory unit 400, And stores the accumulated output data (Adata) in the memory unit 400 to the current frame.

The address control unit 430 designates the address of the memory unit 400 in which the output data of each sub-pixel generated by the data accumulation unit 420 is accumulated and stored. That is, the address control unit 430 controls a read operation or a write operation of the memory unit 400 and controls the data accumulation unit 420 to accumulate And stores the accumulated output data of each subpixel newly generated by the data accumulation unit 420 in the corresponding address of the memory unit 400. [

The gain value calculator 440 calculates a gain value of each pixel based on four color output data (Ro, Go, Bo, Wo) of red, green, blue and white accumulated in the memory unit 400, And calculates a gain value DCG for compensating the deterioration of the organic light emitting diode OLED included in each subpixel according to the driving time amount.

In one embodiment, the gain value calculation unit 440 compares the gain value calculated for each sub-pixel with the gain value of each sub-pixel previously stored in the memory unit 400, and stores the calculated gain value The gain value stored in the memory unit 400 is updated to the newly calculated gain value. If the calculated gain value is equal to the previously stored gain value, the gain value is stored in the memory unit 400 Keep the gain value.

Hereinafter, a method of calculating the gain value for each sub-pixel by the gain value calculating unit 440 will be described in detail with reference to FIGS. 5 to 7. FIG.

5 is a graph for explaining a gain value calculation method according to the first embodiment of the present invention.

The gain value calculating unit 440 calculates the luminance A of each subpixel SP based on the cumulative output data of the subpixels SP stored in the memory unit 400 It is possible to calculate the gain value DCG of each sub-pixel SP for increasing the set initial brightness Yint. For example, the gain value calculator 440 compares the accumulated output data of the corresponding sub-pixel SP with the accumulated output data Ref1, Ref2, Ref3 at a plurality of set compensation points, The luminance A of the sub-pixel SP is increased to the set initial luminance Yint when the accumulated output data of the pixel SP is equal to or greater than the accumulated output data Ref1, Ref2, Ref3 at the respective compensation points (DCG) is calculated.

Each of the accumulated output data Ref1, Ref2 and Ref3 at the plurality of compensation points has a gradually increasing value so as to correspond to the set luminance drop value Yset with respect to the initial luminance Yint of the organic light emitting diode OLED. Up table or a relational expression made up of predictive data for a constant luminance lowering time with respect to the initial luminance Yint of the organic light emitting diode OLED as the set prediction data.

The gain value calculator 440 may include a look-up table in which a gain value DCG having a real value exceeding 1 is mapped according to the accumulated output data, And logic to perform an operation of deriving a gain value (DCG) having a real number value exceeding 1 according to data.

As a result, in the case of the first embodiment, the gain value calculator 440 repeatedly performs the above-described process so that the accumulated output data of each subpixel SP is accumulated in the accumulation output data Ref1, Ref2 , Ref3), a gain value (DCG) having a real number value exceeding 1 is generated.

6 is a graph for explaining a gain value calculation method according to the second embodiment of the present invention.

6, the gain value calculation unit 440 calculates the gain value of each sub-pixel SP (SP) based on the cumulative output data of the sub-pixels SP stored in the memory unit 400, Of the luminance Y_SP of the sub-pixel having the most deteriorated organic light emitting device OLED to the same luminance as the luminance Y_ref of the sub-pixel having the most deteriorated organic light emitting device OLED.

For example, in the case of the second embodiment, the gain value calculator 440 calculates the maximum output data (hereinafter referred to as " maximum output data ") having the maximum value among the accumulated output data of all the subpixels SP stored in the memory unit 400, (Ref1, Ref2, and Ref3) at a plurality of compensation points, and outputs the maximum output data to the accumulation output unit 130 at a point of time when the maximum output data is accumulated at the compensation point (DCG) of each sub-pixel SP based on the difference between the maximum output data and the accumulated output data of each sub-pixel SP when the output data Ref1, Ref2, and Ref3 are equal to or greater than the output data Ref1, Ref2, Ref3.

Each of the accumulated output data Ref1, Ref2 and Ref3 at the plurality of compensation points is used as predictive data corresponding to the set luminance drop points t1, t2 and t3 with respect to the initial luminance Yint of the organic light emitting diode OLED Up table or a relational expression that derives predictive data for a constant luminance lowering time with respect to the initial luminance Yint of the organic light emitting diode OLED.

In the case of the second embodiment, the gain value calculator 40 calculates a gain value (DCG) having a real number less than 1 according to the difference between the accumulated output data and the maximum output data, (DCG) having a real number less than 1 according to the difference value between the accumulated output data and the maximum output data is included in the Look-Up Table, or an operation logic Lt; / RTI >

As a result, in the case of the second embodiment, the gain value calculator 440 repeatedly performs the above-described process so that the maximum output value is obtained every time the maximum output data is equal to or greater than the accumulated output data Ref1, Ref2, Ref3 at the compensation time Generates a gain value DCG of each sub-pixel SP having a real number less than 1 according to the difference between the data and the accumulated output data of the sub-pixel SP, The luminance (Y_SP) is adjusted to be equal to the luminance (Y_ref) of the reference sub-pixel (SP) having the maximum output data.

7 is a graph for explaining a gain value calculation method according to the third embodiment of the present invention.

7, in the third embodiment, the gain value calculator 440 calculates the maximum value among the cumulative output data of all the sub-pixels SP stored in the memory unit 400 at each degradation compensation time (Hereinafter, referred to as " maximum output data ") is set as reference data, the cumulative difference value between the accumulated output data of each sub-pixel (Y_ref) is calculated on the basis of the set reference data, The gain value DCG of each sub-pixel SP can be calculated according to the accumulated difference value of each sub-pixel SP. Here, the gain value (DCG) of each subpixel SP is set such that the luminance (Y_SP1, Y_SP2) of the subpixel having the cumulative difference value is reduced to the luminance (Y_ref) of the subpixel having the maximum output data , For example, the gain value DCG of each sub-pixel SP may be set to a real number value of less than 1, which is greater than zero. The gain value DCG of each subpixel SP is calculated differently depending on the cumulative difference value of each subpixel SP and is updated to a new value at each of the deterioration compensation points by the calculation process described above.

The gain value calculator 440 can calculate the gain value DCG of each subpixel SP using various algorithms in addition to the gain value DCG calculation method according to the embodiment described above.

Referring again to FIG. 4, the operation unit 450 reads the accumulated white output data from the memory unit 400 and determines whether the accumulated white output data is equal to or greater than a threshold value. In one embodiment, the threshold value may be set to predictive data whose luminance of the white sub-pixel corresponds to a point of time when the luminance of the white sub-pixel is lower than the initial luminance. That is, the threshold value is set to the experimentally calculated accumulated white output data at the time when the yellowish phenomenon occurs as the color coordinates (CIEx, CIEy) shift as the white organic light emitting device of the white sub- .

When it is determined that the accumulated white output data is equal to or more than the threshold value, the operation unit 450 calculates the three color ratio values of red, green, and blue according to the accumulated white input data, To the color data converter 200.

In one embodiment, the operation unit 450 may calculate the three color ratio values of red, green, and blue according to the accumulated white input data using Equation 1 below.

RL, gL, and bL represent the color ratios of red, green, and blue, respectively, and rX, rY, and rZ represent the red, green, and blue color ratios of the red color included in the accumulated white output data on the chromaticity coordinates, GX, gY, and gZ represent the X, Y, and Z coordinates of the green included in the accumulated white output data on the chromaticity coordinates, bX, bY, and bZ represent the accumulated white Y, and Z coordinates included in the output data, and wX, wY, and wZ represent the X, Y, and Z coordinates of the accumulated white output data on the color coordinate system.

As described above, the OLED display and the driving method thereof according to an embodiment of the present invention compensate for the deterioration of the OLED based on accumulated output data of each sub-pixel, When the cumulative output data of the pixels is equal to or more than the threshold value, it is determined that deterioration has occurred in the white sub-pixels, and based on the accumulated output data of the white sub-pixels of each unit pixel, G, and B are converted into the four-color input data Ri, Gi, Bi, and Wi by feeding back the three-color input data R, G, and B to the four- The color temperature of the white sub-pixel can be corrected so that the color temperature of the white organic light emitting device becomes the target color temperature, thereby preventing the color coordinate change and the yellowish phenomenon due to deterioration of the white organic light emitting device, A residual image caused by can be prevented.

8 is a graph showing changes in color temperature before and after applying the color temperature correction technique according to the present invention.

8, when the color temperature of the white sub-pixel is converted into the target color temperature in the process of converting the three-color input data R, G, B into the four-color input data Ri, Gi, Bi, Wi, It can be seen that when the color ratio value is corrected, the color temperature is improved compared to before the correction.

Hereinafter, a driving method of the OLED display according to the present invention will be described with reference to FIG.

9 is a flowchart illustrating a method of driving an OLED display according to an exemplary embodiment of the present invention.

First, as shown in FIG. 9, the three-color input data R, G, and B of red, green, and blue are received (S900).

Subsequently, the three-color input data (R, G, B) is converted into four-color input data Ri, Gi, Bi, Wi of red, green, blue and white using the first lookup table (S910).

In one embodiment, the first look-up table records the target three-color ratio values to be applied to the three-color input data (R, G, and B) and the target color temperature of the white sub-pixel. According to this embodiment, a target color ratio value matching the target color temperature of the three-color input data (R, G, B) and the white sub-pixel is selected on the first lookup table, And generates the four-color input data Ri, Gi, Bi, and Wi by applying the input data to the input data R, G, and B, respectively.

Thereafter, it is determined whether or not the gain value to be reflected is updated in the four-color input data Ri, Gi, Bi, Wi (S920). As a result of the determination, if there is no update of the gain value, the four-color output data (Ro, Go, Bo, Wo) is generated by reflecting the gain value generated in the previous frame on the four-color input data Ri, Gi, Go, Bo, and Wo are generated by reflecting the updated gain values to the four-color input data Ri, Gi, Bi, and Wi when there is an update of the gain value (S925) ).

At this time, the gain value to be initially reflected in the four-color input data Ri, Gi, Bi, Wi may be preset and stored in the memory unit.

Thereafter, output data of each of the accumulated sub-pixels up to the previous frame in which the four-color output data (Ro, Go, Bo, Wo) of red, green, After the read (S940), the four-color output data (Ro, Go, Bo, Wo) generated in S930 and the output data of each sub-pixel read in S940 are summed and stored again at the corresponding address in the memory S950). Accordingly, the output data of each sub-pixel accumulated up to the current frame is recorded in the corresponding address of the memory unit.

Thereafter, the accumulated output data of the white sub-pixels up to the current frame stored in the memory unit is read (S960), and it is determined whether the accumulated output data of the white sub-pixels is equal to or greater than the threshold value (S970) .

As a result of the determination in S970, if the cumulative output data of the white sub-pixel is equal to or greater than the threshold value, it is determined that the white sub-pixel has deteriorated. Based on the accumulated output data of the white sub- (S980). At this time, the three-color ratio value can be calculated using the above-described equation (1).

In one embodiment, the threshold value may be set to predictive data whose luminance of the white sub-pixel corresponds to a point of time when the luminance of the white sub-pixel is lower than the initial luminance. That is, the threshold value is set to the experimentally calculated accumulated white output data at the time when the yellowish phenomenon occurs as the color coordinates (CIEx, CIEy) shift as the white organic light emitting device of the white sub- .

Next, the first lookup table is updated based on the three-color ratio value calculated in S980 so that the color temperature of the white sub-pixel becomes the target color temperature (S990), and the newly inputted three-color input data R, The above-described process is repeatedly performed.

In one embodiment, the first three-color ratio values are recorded in the first look-up table, which are the red, green, and blue color ratio values that cause the color temperature of the white sub-pixel to become the target color temperature, The first look-up table can be updated by correcting the target three-color ratio value recorded in the first look-up table.

Although not shown in FIG. 9, the method of driving an organic light emitting display according to the present invention may further include a step of outputting accumulated red, green, blue, and white output data to compensate for deterioration of the organic light emitting elements included in each sub- The gain value of each sub-pixel is calculated, and the calculated gain value is compared with the gain value of each sub-pixel previously stored in the memory unit, and the gain value of each sub-pixel previously stored in the memory unit And a step of updating the data.

The method of calculating the gain value of each sub-pixel has been described above with reference to Figs. 5 to 7, and thus a detailed description thereof will be omitted.

Hereinafter, a method of updating the first lookup table will be described with reference to FIG.

10 is a flowchart illustrating a first lookup table updating method according to an embodiment of the present invention.

10, the three-color ratio value calculated from the cumulative output data of the white sub-pixel and the target three-color ratio value for making the color temperature of the white sub-pixel to be the target color temperature are compared to calculate the deviation (S1000).

Then, a three-color ratio value correction amount corresponding to the deviation calculated in S1000 and the target color temperature on the second lookup table is selected (S1100). At this time, the second lookup table 206 records the target color temperature and the three-color ratio value correction amount to be applied to each deviation. Therefore, the three-color ratio value correction amount matching the deviation calculated in S1100 and the target color temperature on the second lookup table is extracted.

Then, the first lookup table is updated by reflecting the three-color ratio value correction amount to the target three-color ratio value (S1200).

In the embodiment described above, the first look-up table is updated by reflecting the three-color ratio value correction amount to the target three-color ratio value recorded in the first look-up table and correcting the target three-color ratio value.

However, in another embodiment, another target three-color ratio value having the same value as the result of reflecting the three-color ratio value correction amount to the target three-color ratio value is selected on the first lookup table, It is possible to generate the four-color input data Ri, Gi, Bi, Wi by applying the color ratio value to the three-color input data R, G,

The driving method of the OLED display may be implemented in a form of a program that can be performed using various computer means. The program for performing the driving method of the OLED display may be a hard disk, a CD-ROM, Readable recording medium such as a DVD, a ROM, a RAM, or a flash memory.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: display panel 200: four-color data conversion section
250: deterioration compensating unit 300: panel driving unit
201: data conversion unit 202: comparison unit
203: correction amount calculating unit 204: table updating unit
205: first lookup table 206: second lookup table
400: memory part 410: data compensating part
420: Data accumulation unit 430: Address control unit
440: gain value calculation unit 450:

Claims (10)

A display panel including a plurality of unit pixels constituted by red, green, blue and white sub-pixels each having an organic light emitting element;
A four-color data converter for converting red, green, and blue input data into red, green, blue, and white input data using a first lookup table (LUT);
Green, blue, and white output data by reflecting a predetermined gain value to the red, green, blue, and white input data, and outputting the red, green, A deterioration compensation unit for calculating the three color ratio values of red, green, and blue according to the accumulated white output data and feeding back the calculated three color ratio values to the four-color data conversion unit; And
And a panel driver for supplying the red, green, blue, and white output data to the corresponding sub-pixel to output a predetermined image through the display panel,
Wherein the four-color data converter updates the first look-up table based on the fed-back three-color ratio value so that a color temperature of the white sub-pixel becomes a target color temperature. The method according to claim 1,
Wherein the first lookup table records a target three color ratio value which is a color ratio value of red, green, and blue so that a color temperature of the white subpixel becomes the target color temperature,
Wherein the four-color data conversion unit corrects the target three-color ratio value recorded on the first look-up table based on the fed-back three-color ratio value. The method according to claim 1,
Wherein the four-
A comparison unit for calculating a deviation by comparing the target three-color-ratio value so that the feedback color-temperature ratio and the color temperature of the white sub-pixel are the target color temperature;
A correction amount calculating unit that calculates a three-color ratio value correction amount corresponding to the deviation calculated by the comparing unit on the second look-up table and the target color temperature; And
And a table updating unit for updating the first lookup table by reflecting the three-color ratio value correction amount to the target three-color ratio value. The method according to claim 1,
Wherein the deterioration compensator comprises:
And a gain value calculation unit for calculating the predetermined gain value for each sub-pixel based on the accumulated output data of red, green, blue, and white to compensate for deterioration of the organic light emitting diode included in each sub-pixel And the organic light emitting display device. The method according to claim 1,
Wherein the deterioration compensator comprises:
Determining whether the accumulated white output data is equal to or greater than a threshold value and calculating three color ratio values of red, green, and blue according to the accumulated white input data when the accumulated white output data is equal to or greater than a threshold value And an arithmetic unit for feeding back the data to the four-color data converter. A method of driving an organic light emitting display including a unit pixel including red, green, blue, and white sub-pixels each having an organic light emitting element,
Converting the red, green, and blue input data into red, green, blue, and white input data using a first lookup table;
Generating red, green, blue, and white output data by reflecting a predetermined gain value on the red, green, blue, and white input data; And
Accumulating and storing the red, green, blue, and white output data in the memory every predetermined accumulation period;
Calculating three color ratio values of red, green, and blue according to the accumulated white output data; And
And updating the first look-up table based on the calculated three-color ratio value so that a color temperature of the white sub-pixel becomes a target color temperature. The method according to claim 6,
Wherein the first lookup table records a target three color ratio value which is a color ratio value of red, green, and blue so that a color temperature of the white subpixel becomes the target color temperature,
Wherein the updating step corrects the target three-color ratio value recorded in the first look-up table based on the calculated three-color ratio value. The method according to claim 6,
Wherein the updating comprises:
Calculating a deviation by comparing the calculated three-color ratio value and a target three-color ratio value such that a color temperature of the white sub-pixel is the target color temperature;
Calculating a three-color ratio value correction amount corresponding to the calculated deviation and the target color temperature on a second look-up table; And
And updating the first lookup table by reflecting the three-color ratio value correction amount to the target three-color ratio value. The method according to claim 6,
Wherein the predetermined gain value is calculated for each sub-pixel based on the accumulated red, green, blue, and white output data to compensate for deterioration of the organic light emitting diode included in each sub-pixel Wherein the organic light emitting display device comprises: The method according to claim 6,
In the calculating step,
Determining whether the accumulated white output data is equal to or greater than a threshold value and calculating three color ratio values of red, green, and blue according to the accumulated white input data when the accumulated white output data is equal to or greater than a threshold value Wherein the organic light emitting display device comprises:

Images