KR102042531B1 - Organic light emitting diode display device and method of driving the same - Google Patents

Abstract

The present invention relates to an organic light emitting diode display and a driving method thereof capable of compensating for characteristics variation between pixels due to deterioration by quickly and accurately sensing the characteristics of each pixel even during a display period. A display panel having a structure in which a plurality of subpixels each having a different color in a plurality of horizontal lines is repeatedly arranged in a horizontal direction; The data driver includes a data driver having a sensing unit for dividing each horizontal line into a plurality of groups composed of a plurality of spatially distributed subpixels to sense characteristics of each subpixel for each group. When driving in the sensing mode to drive the remaining group in the display mode.

Description

Organic light emitting diode display and its driving method {ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE AND METHOD OF DRIVING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode display, and more particularly, to an organic light emitting diode display and a method of driving the same, capable of compensating for characteristics variation between pixels due to degradation by quickly and accurately sensing pixel characteristics without a limitation of a sensing period. .

An organic light emitting diode (OLED) display device is a self-luminous device that emits an organic light emitting layer by recombination of electrons and holes. The organic light emitting diode (OLED) display device is expected to be a next generation display device because of its high brightness, low driving voltage, and ultra-thin film.

Each of the plurality of pixels constituting the OLED display device includes an OLED device composed of an organic light emitting layer between an anode and a cathode, and a pixel driving circuit driving the OLED device independently. The pixel driving circuit mainly includes a switching thin film transistor (hereinafter, referred to as TFT), a capacitor, and a driving TFT. The switching TFT charges the capacitor with a voltage corresponding to the data signal in response to the scan pulse, and the driving TFT controls the amount of light emitted from the OLED element by controlling the amount of current supplied to the OLED element according to the magnitude of the voltage charged in the capacitor. . The amount of light emitted by the OLED element is proportional to the current supplied from the driving TFT.

However, OLED display devices have a problem of luminance non-uniformity between pixels due to various causes. For example, characteristic variations such as threshold voltages (hereinafter referred to as Vth) and mobility of the driving TFTs due to process variations, deviations in power supply voltages due to line resistances according to pixel positions, and driving appearing as the driving time elapses. The luminance non-uniformity problem occurs due to deterioration variation of the TFT or OLED element. In general, the characteristic variation of the initial driving TFT causes spots or patterns on the screen, and the characteristic variation due to deterioration of the driving TFT or the OLED element generated while driving the OLED element reduces the lifespan of the OLED display panel or causes image retention. There is a problem that occurs.

In order to solve this problem, a prior patent such as US Pat. No. 7,834,825 discloses an external data compensation method of sensing input current based on a sensing result by sensing a driving current of each pixel. However, the prior patent uses a method of measuring the current flowing to the power line (VDD or VSS line) of the panel while lighting up each pixel, so that the current sensing time is increased due to parasitic capacitors present in parallel in the power line when the resolution is increased. There is a problem that high speed sensing is difficult due to delay.

For this reason, the prior art patent can sense and compensate for the characteristic deviation between the initial driving TFTs in the inspection process before shipment of the product, but the deterioration deviation of the driving TFT generated while driving the OLED display device after the shipment of the product is measured and Compensation is difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problem, and an object of the present invention is to solve the characteristic variation between pixels due to degradation by quickly and accurately sensing the characteristics of each pixel even during the display period. A display device and a driving method thereof are provided.

In order to solve the above problems, an OLED display device according to an embodiment of the present invention includes a display panel having a structure in which a plurality of sub-pixels each having a different color, the plurality of horizontal lines are arranged repeatedly in a horizontal direction; Built-in sensing unit that senses the characteristics of each subpixel by dividing each horizontal line into a plurality of groups composed of a plurality of spatially distributed subpixels, and driving one group in the sensing mode in each horizontal line. And a data driver for driving the remaining groups in display mode.

The sensing unit includes a first group of 5n-4th subpixels (n is a natural number), a second group of 5n-3th subpixels, and a third group of 5n-2th subpixels of each horizontal line. A group is divided into a fourth group consisting of 5n-1 subpixels, and a fifth group consisting of 5nth subpixels to sense each group.

Each of the plurality of groups includes subpixels of different colors constituting different pixels.

The sensing unit selects and senses one of a plurality of groups in response to a sensing channel selection signal from the outside, and a selection order of the plurality of groups by the sensing channel selection signal may be randomly changed at least in one horizontal line or at least one frame unit. have.

The OLED display according to the exemplary embodiment of the present invention generates the sensing channel selection control signal and calculates the luminance correction value by calculating the luminance reduced by the group driven in the sensing mode in each horizontal line, and calculating the luminance correction value. A data processor which compensates for luminance of surrounding pixels; By supplying the input data from the data processing unit to the data driver, controlling the driving of the data driver, inputting the sensed data from the subpixels of each group through the sensing unit, and calculating the data compensation value using the sensed data. And a timing controller for storing and compensating for data to be supplied to the data driver with the stored data compensation value.

The data processor calculates luminance reduced by each group driven in the sensing mode in units of at least five pixels, and distributes the calculated luminance value from at least five pixels to neighboring pixels driven in the display mode for each pixel. The luminance compensation value is calculated.

The data processor analyzes input data corresponding to at least five pixels, and maps sensing data to subpixels driven in a sensing mode among the at least five pixels, and subpixels of the input data into subpixels driven in the display mode. Selectively change the location to map.

The data processing unit distributes the luminance average value of two adjacent pixels in at least five pixels to the peripheral pixels driven in the display mode and applies the luminance correction value of each peripheral pixel.

The timing controller repeats sensing of each subpixel through the sensing unit to calculate a data compensation value corresponding to each subpixel.

Each of the plurality of groups includes R / W / G / B subpixels constituting different pixels or R / G / B subpixels constituting different pixels.

In the method of driving an OLED display device according to an exemplary embodiment of the present invention, for a display panel having a structure in which a plurality of horizontal pixels are arranged in a horizontal direction, a plurality of subpixels having different colors are spatially arranged in each horizontal line. Dividing into a plurality of groups of distributed plurality of subpixels; And sensing the characteristics of each subpixel for each group divided in each horizontal line, and driving the other group in the display mode when driving one group in the sensing mode in each horizontal line.

The OLED display and the driving method thereof according to the present invention divides each horizontal line HLi into a plurality of groups each having different colors and spatially separated subpixels, thereby sensing characteristics of each subpixel for each group. When one group is driven in the sensing mode, the other group may be driven in the display mode.

Accordingly, the OLED display and the driving method thereof according to the present invention can sense the characteristics of the subpixels in the entire period of the vertical synchronization signal (each frame) irrespective of the display period. The period of time to be reduced can be significantly shortened. Accordingly, deterioration of the subpixels can be compensated in real time by fast sensing of the entire subpixels, or more accurate values can be sensed by repetitive sensing of the same subpixels to compensate for the degradation of the subpixels.

In addition, the OLED display and the driving method thereof according to the present invention can minimize the deterioration of image quality by compensating for the luminance reduced by the subpixels driven in the sensing mode through data modulation of peripheral pixels.

1 is a diagram schematically illustrating a method of sensing pixel characteristics of an OLED display device according to the related art.
2 is a diagram illustrating a method of sensing pixel characteristics of an OLED display according to an exemplary embodiment of the present invention.
3A through 3E are diagrams illustrating a sensing method using a sensing unit provided in an OLED display according to an exemplary embodiment of the present invention.
4A and 4B are diagrams illustrating the sensing period of the prior art and the OLED display device according to the present invention.
5A and 5B illustrate a method of compensating for luminance reduced by a subpixel sensed in an OLED display according to an exemplary embodiment of the present invention.
6 is a diagram illustrating a sensing sequence of first to fifth groups according to sensing channel selection signals in each horizontal line of the OLED display according to an exemplary embodiment of the present invention.
7 is a block diagram schematically illustrating a configuration of an OLED display device according to an exemplary embodiment of the present invention.
8 is a block diagram showing an internal configuration of a data processing unit shown in FIG.
9 is a flowchart illustrating a data processing method of the data processing unit shown in FIG. 8 in stages.

Prior to the description of the embodiments of the present invention, the prior art related to the present invention will be described first to help understand the present invention.

1 is a view briefly illustrating a method of sensing pixel characteristics of an OLED display device according to the related art.

Referring to FIG. 1, only a sensing method for one horizontal line (HLi, i is a natural number) among a plurality of horizontal lines constituting the OLED display panel is representatively shown. One horizontal line HLi has a structure in which pixels consisting of four subpixels of red (hereinafter R), white (hereinafter W), green (hereinafter G) and blue (hereinafter B) are repeatedly arranged in the horizontal direction.

The sensing unit embedded in the data driver senses pixel characteristics of each R / W / G / B group by grouping the R / W / G / B subpixels of one horizontal line HLi by color.

For example, for one horizontal line HLi, an R group composed of R subpixels is sequentially sensed in a subpixel unit in the first sensing period SP1, and the W subpixels in the second sensing period SP2. Sequentially sensing the W group in subpixel units, sequentially sensing the G group composed of the G subpixels in the third sensing period SP3 in the subpixel unit, and B subpixels in the fourth sensing period SP4. The B group consisting of the sub-pixels are sequentially sensed.

As the color group selected in each sensing period SP is driven in the sensing mode and does not emit light, the luminance of the horizontal line sensed is reduced. For this reason, each sensing period SP is limited to a non-display period except the display period, that is, the blank period of the vertical synchronization signal, so that the luminance reduction due to the sensing mode is not recognized by the viewer, and one of the horizontal lines in each blank period is also included. Only color groups are sensed.

Accordingly, in order to sense all the subpixels of one horizontal line HLi, blank periods of four frames corresponding to the first to fourth sensing periods SP1 to SP4 are required, so that k (k is a natural number) In order to sense all subpixels in an OLED display panel having horizontal lines, a blank period of k * 4 frames is required. For example, in an OLED display panel having 1080 horizontal lines, a blank period of 1080 * 4 frames is required to sense all subpixels.

Therefore, since the OLED display device according to the prior art needs to take a long time to sense all the subpixels, it is difficult to sense the characteristics of the subpixels to compensate data in real time.

In order to solve the problems of the prior art, the present invention is to propose an OLED display device and a driving method thereof that can quickly and accurately sense the characteristics of the sub-pixel even in the display period without the limitation of the sensing period.

The present invention also proposes an OLED display device and a driving method thereof capable of compensating the luminance of adjacent pixels so that the luminance reduction due to the sensing mode of the subpixel is not recognized by the user.

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

FIG. 2 is a diagram schematically illustrating a method of sensing pixel characteristics of an OLED display according to an exemplary embodiment of the present invention.

Referring to FIG. 2, each horizontal line HLi in which R / W / G / B subpixels are alternately arranged repeatedly is divided into a plurality of groups and sensed, and each group has a different color and is spatially dispersed in R. The / W / G / B subpixels are mixed, and when one group is driven in the sensing mode in each horizontal line HLi, the other group can be simultaneously driven in the display mode.

In detail, each horizontal line HLi is divided into first to fifth groups sensed according to the continuous sensing channel selection signal SCS.

According to the sensing channel selection signal (SCS), a first group of 5n-4 (n is a natural number) subpixels, a second group of 5n-3 subpixels, and 5n-2 subpixels A third group, a fourth group of 5n-1 subpixels, and a fifth group of 5nth subpixels are sequentially or randomly selected and sensed. Subpixels included in each selected group are sensed sequentially.

Referring to FIG. 2, in one horizontal line HLi of the OLED display of the present invention, R1 corresponding to 5n-4th subpixels as a first group in response to the sensing channel selection signal SCS [000]. / W2 / G3 / B4... The characteristics of the subpixels are sequentially sensed, and W1 / G2 / B3 / R5..., Corresponding to the 5n-3rd subpixels of the second group in response to the sensing channel selection signal SCS [001]. The characteristics of the subpixels are sequentially sensed, and in response to the sensing channel selection signal SCS [010], the third group includes G1 / B2 / R4 / W5... Corresponding to 5n-2th subpixels. The characteristics of the subpixels are sequentially sensed, and B1 / R3 / W4 / G5..., Corresponding to the fourth group of 5n-1 subpixels in response to the sensing channel selection signal SCS [011]. The characteristics of the subpixels are sequentially sensed, and R2 / W3 / G4 / B5... Corresponding to the 5th subpixels of the fifth group in response to the sensing channel selection signal SCS [100]. The characteristics of the subpixels are sequentially sensed. Accordingly, R / W / G / B subpixels are mixed in the sensed group.

When one group is driven in the sensing mode in each horizontal line HLi, the other group may be driven in the display mode. Accordingly, the OLED display device of the present invention does not limit the sensing period to the blank period (non-display period) of the vertical synchronization signal, and the characteristics of the subpixels in the entire period of the vertical synchronization signal (each frame) regardless of the display period. Since the sensing can be performed, the time required for sensing the entire subpixels can be significantly shorter than the above-described prior art. Accordingly, deterioration of the subpixels can be compensated in real time by fast sensing of the entire subpixels, or more accurate values can be sensed by repetitive sensing of the same subpixels to compensate for the degradation of the subpixels.

3A through 3E are diagrams illustrating a sensing method using a sensing unit provided in an OLED display according to an exemplary embodiment of the present invention.

3A to 3E, the OLED display device of the present invention includes a display panel 10 and a sensing unit 40, and the sensing unit 40 is usually embedded in a data driver.

The sensing unit 40 includes an input channel selector 22 for selecting an input channel, an output channel selector 24 for selecting an output channel, and a multiplexer sequentially supplying output signals of the output channel selector 24 ( MUX) and an analog-to-digital converter (hereinafter, ADC) for converting an output signal from the MUX into digital data and outputting the sensed data.

The input channel selector 22 includes first to fifth switches SW1 to SW5 for selecting input channels of the first to fifth groups, respectively, in response to the sensing channel select signal SCS.

The output channel selector 24 includes first to fifth sampling and hold groups SH1 to SH5 for selecting output channels of the first to fifth groups, respectively, in response to the sensing channel selection signal SCS. do.

Referring to FIG. 3A, in response to the channel select signal SCS [000], the first switch SW1 group is selected by the input channel selector 22, and the first sampling & Hold (SH1) group is selected. The sensing signal SS is supplied to the 5n-4th data line DL5n-4 of the display panel 10 through the selected first switch SW1 group to be the first group in one horizontal line of the display panel 10. The 5n-4th subpixels are driven in the sensing mode. The OLED device does not emit light in the subpixel driven in the sensing mode. The 5n-4th subpixels driven in the sensing mode output a signal reflecting the characteristics of each subpixel through the 5n-4th sensing line SL5n-4, and the output signal is the first sampling & hold group SH1. After sampling and holding, the signals are sequentially output to the ADC through MUX, converted into digital data by the ADC, and output as sensed data.

Referring to FIG. 3B, in response to the channel selection signal SCS [001], the second switch SW2 group is selected by the input channel selector 22, and the second sampling & Hold (SH2) group is selected. The sensing signal SS is supplied to the 5n-3rd data line DL5n-3 of the display panel 10 through the selected second switch SW2 group to be the second group in one horizontal line of the display panel 10. The 5n-3th subpixels are driven in the sensing mode. The signal output from the 5n-3rd subpixels driven in the sensing mode via the 5n-3rd sensing line SL5n-3 is sampled and held by the second sampling & hold group SH2, and then MUX Through sequentially output to the ADC, the ADC is converted to digital data and output as the sensed data.

Referring to FIG. 3C, in response to the channel select signal SCS [010], the third switch SW3 is selected by the input channel selector 22, and the third sampling & Hold (SH3) group is selected. The sensing signal SS is supplied to the 5n-2nd data line DL5n-2 of the display panel 10 through the selected third switch SW3 group to be the third group in one horizontal line of the display panel 10. The 5n-2th subpixels are driven in the sensing mode. The signal output from the 5n-2th subpixels driven in the sensing mode via the 5n-2th sensing line SL5n-2 is sampled and held by the third sampling & hold group SH3 and then MUX. Through sequentially output to the ADC, the ADC is converted to digital data and output as the sensed data.

Referring to FIG. 3D, in response to the channel selection signal SCS [011], the fourth switch SW4 group is selected in the input channel selector 22, and the fourth sampling & Hold (SH4) group is selected. The sensing signal SS is supplied to the 5n-1th data line DL5n-1 of the display panel 10 through the selected fourth switch SW4 group to be the fourth group in one horizontal line of the display panel 10. The 5n-1th subpixels are driven in the sensing mode. The signal output from the 5n-1th subpixels driven in the sensing mode via the 5n-1th sensing line SL5n-1 is sampled and held by the fourth sampling & hold SH4 group, and then MUX. Through sequentially output to the ADC, the ADC is converted to digital data and output as the sensed data.

Referring to FIG. 3E, in response to the channel select signal SCS [100], the fifth switch SW5 is selected by the input channel selector 22, and the fifth sampling & Hold (SH5) group is selected. The sensing signal SS is supplied to the 5nth data line DL5n of the display panel 10 through the selected fifth switch SW5 group so that the 5nth subpixel as the fifth group in one horizontal line of the display panel 10. Are driven in the sensing mode. The signal output from the 5nth subpixels driven in the sensing mode via the 5nth sensing line SL5n is sampled and held by the fifth sampling & hold group SH5 and then sequentially transmitted to the ADC through MUX. The data is converted into digital data by the ADC and output as sensed data.

Here, the sensing lines SL5n-4 to SL5n are reference lines for supplying a reference voltage when driving each subpixel, or data lines DL5n-4 to DL5n for supplying the sensing signals, or are different from these lines. It may be a sensing line provided separately.

3A to 3E, the subpixels of the other groups except one group among the horizontal lines are supplied with the corresponding data signal through the data driver and driven in the display mode to emit light. Therefore, each horizontal line may be divided into a group driven in the sensing mode and a group driven in the display mode and driven simultaneously.

4A and 4B are diagrams illustrating the sensing period of the prior art and the OLED display device according to the present invention.

Referring to FIG. 4A, the sensing period in the OLED display according to the prior art is limited to the blank period A of the vertical synchronization signal Vsync. Because of this, if the display panel has 1080 horizontal lines and is driven at a frequency of 120 Hz, the time taken to sense the entire subpixel is "(1080 * 4 * A) / 120Hz" (where 4 is the number of division groups, A Is a sensing period of one group).

Referring to FIG. 4B, the OLED display according to the present invention can sense the entire period B of the vertical synchronization signal Vsync. Accordingly, if the display panel has 1080 horizontal lines and is driven at a frequency of 120 Hz, the time taken to sense the entire subpixel is "(1080 * 5 * A) / (120Hz * B)" (where 5 is divided). Since the number of groups, A, is a sensing period of one group), it can be seen that 0.8 * B times is reduced compared to the prior art of FIG. 4A.

5A and 5B illustrate a method of compensating for luminance reduced by a subpixel sensed in an OLED display according to an exemplary embodiment of the present invention.

When the OLED display according to the present invention senses the characteristics of the subpixels regardless of the display period in groups, the luminance reduced according to the off of the sensed subpixels is compensated by modulating the data of the remaining pixels driven in the display mode. Can be.

Referring to FIG. 5A, when the 5n-4th subpixels, which are the first group of the five pixels P1 to P5, are driven in the sensing mode and turned off, and the subpixels of the remaining group are driven in the display mode, 5 pixels It can be seen that the luminance corresponding to one pixel is reduced than when all of P1 to P5 are driven in the display mode. In order to compensate for the reduced luminance, the position of the subpixel to which each data is mapped is selectively changed, and the luminance compensation value is distributed and applied to the remaining four pixels driven in the display mode.

For example, sensing data is mapped to each of the R / W / G / B subpixels corresponding to the group driven in the sensing mode in the five pixels P1 to P5 and the R / W / of the first pixel P1 is mapped. In the G / B data, only the R data is changed in the position of the subpixel and mapped to the W / G / B / R subpixel, respectively. In the R / W / G / B data of the fourth pixel P4, the position of the subpixel of only the B data is changed and mapped to the B / R / W / G subpixel, respectively. The R / W / G / B data of the fifth pixel P5 is mapped to each of the R / W / G / B subpixels as it is.

In addition, since the R / W / G / B data of the second and third pixels P2 and P3 should be overlapped with the G / B / R / W subpixel of one pixel, the second and third pixels P2, The luminance average value "(YP2 + YP3) / 2 = α" is calculated from the R / W / G / B data of P3), and the R / W / G / B data corresponding to the luminance average value α is converted into G / B /. Can be mapped to R / W subpixels. In this case, when the luminance average value α of the two pixels P2 and P3 is applied to only one pixel among the four pixels driven in the display mode, the luminance average value α is higher than that of driving the five pixels in the display mode. The luminance is insufficient as much.

Therefore, as shown in FIG. 5B, the luminance average value α of the two pixels P2 and P3 corresponding to the luminance decrease during driving of the sensing mode is divided into four equal parts, and the luminance average value α / 4 divided into four equal parts is displayed in the display mode. The luminance is compensated by adding to the luminances YP1, (YP2 + YP3) / 2, YP4, and YP5 of each of the four pixels driven by. Accordingly, even if the subpixels driven in the sensing mode are turned off, the deterioration of image quality can be minimized by compensating for the luminance of the remaining subpixels driven in the display mode.

In addition, since the OLED display according to the present invention can compensate for the luminance reduced by the subpixels driven in the sensing mode by data modulation of the remaining pixels driven in the display mode, the group of sensed subpixels does not emit light during the corresponding frame. Can be turned off. In this case, more sensing time can be secured, and the OLED device of the corresponding subpixel is turned off during sensing, thereby extending the life of the OLED device.

6 is a diagram illustrating a sensing sequence of first to fifth groups according to a sensing channel selection signal SCS in each horizontal line of the OLED display according to an exemplary embodiment of the present invention.

Referring to FIG. 6, first to fifth groups may be sequentially sensed according to a sensing channel selection signal SCS in each horizontal line. In this case, as each group is sensed, the subpixels of the group are turned off, so that the resolution of each horizontal line is reduced to 1/5, which may be recognized by the user.

In order to prevent this, the OLED display device according to the present invention dithers the sensing order of the first to fifth groups for at least one horizontal line unit and / or at least one frame unit to randomly change the sensing order. Accordingly, since the subpixels driven in the sensing mode on one screen are spatially randomly distributed, the reduction in resolution can be prevented from being recognized by the user.

7 is a block diagram schematically illustrating a configuration of an OLED display device according to an exemplary embodiment of the present invention.

The OLED display shown in FIG. 7 includes a display panel 10, a data driver 30, a gate driver 40, a gamma voltage generator 50, a timing controller 60, and a data processor 70.

The luminance is selectively compensated for and output to the timing controller 60 according to whether the input data from the outside of the data processor 70 corresponds to the sensing line and the sensing group. To this end, the data processing unit 70, as shown in Figure 8, the data input unit 72, the sensing control unit 74, the buffer 75, the data mapping unit 76, the brightness correction unit 78 and the data output unit 80. Data processing is performed according to the flowchart of the data processing method shown in FIG. It demonstrates with reference to FIG. 8 and FIG.

The sensing controller 74 generates a sensing line selection signal indicating a horizontal line to be sensed using preset dithering information, and a sensing channel selection signal indicating a subpixel of a group sensed in the sensing horizontal line, and sensing the sensing line selection signal. Using the line selection signal and the sensing channel selection signal, it is determined whether the input data corresponds to the horizontal line to which the data is sensed and the subpixels of the sensing group (S2 and S6). If it is determined that the input data do not correspond to the sensing horizontal line, the sensing controller 74 outputs the input data to the data output unit 80 through the buffer 75 (S4). The buffer 75 serves to match timing between circuit blocks. If it is determined that the input data corresponds to the subpixels of the sensing horizontal line and the sensing group, the sensing controller 74 outputs the data to the data mapping unit 76 and the data mapping unit 76 instead of the input data in the corresponding subpixels. Maps and outputs the data to the data output unit 80 (S7). On the other hand, if it is determined that the input data corresponds to the sensing horizontal line but the sensing group is not a subpixel, the sensing controller 74 outputs the input data to the data mapping unit 76 and the luminance corrector 78. The sensing controller 74 also supplies a sensing line selection signal and a sensing channel selection signal to the timing controller 60.

As described above with reference to FIGS. 5A and 5B, the data mapping unit 76 analyzes data in units of five pixels so that the subpixels of the remaining four pixels except for the four subpixels to which the sensing data is mapped for the sensing mode. The position of the subpixel to which the input data is mapped is selectively changed so as to correspond to (S8). Since five pixels of data must be mapped to four pixels, two pixels of data are redundantly mapped to one pixel.

The luminance correction unit 78 calculates a luminance average value from data of two pixels overlapped with one pixel in the data mapping unit 76, and divides the luminance average value into four equal parts to calculate luminance correction values of four pixels. (S10). The luminance corrector 78 corrects the luminance of each pixel using the luminance correction value and outputs the luminance to the data output unit 80 (S12). In this case, since the RWGB data input from the outside is grayscale data, the luminance corrector 78 converts the RWGB data into 2YCbCr data including the luminance component Y through color space conversion to calculate the luminance average value and the luminance correction value. After compensating for the luminance of each pixel with the calculated luminance correction value, the RWGB data with luminance compensated for is output to the data output unit 80 by inverting the color space. On the other hand, the brightness correction unit 78 outputs the sensing data from the data mapping unit 76 to the data output unit 80 as it is.

The data output unit 80 outputs the output data from the buffer 75 and the luminance corrector 78 to the timing controller 60 (S14).

The timing controller 60 generates and outputs a data control signal and a gate control signal for controlling the driving timing of the data driver 30 and the gate driver 40, respectively, using the plurality of synchronization signals from the data processing unit 70. . The timing controller 60 outputs input data from the data processing unit 70 to the data driver 30.

The timing controller 60 outputs the sensing channel selection signal to the data driver 30 in response to the sensing horizontal line selection signal from the data processing unit 70 so that the data driver 30 corresponds to the sensing channel selection signal in the corresponding horizontal period. Controls to output the characteristics of the subpixels of the sensing group. The output signal (ie, sensed data) of each subpixel sensed through the data driver 30 corresponds to a pixel current that varies according to Vth, mobility, OLED characteristics, etc. of the driving TFT that determines the characteristics of each subpixel. Since the data sensed from each subpixel is detected, the characteristics of each subpixel may be detected and compensated for. To this end, the timing controller 60 includes a compensation value detector and a compensation unit.

The compensation value detector detects a compensation value for compensating Vth and mobility deviation of the driving TFT according to each pixel current using the sensed data of each subpixel output from the data driver 30 and stores the compensation value in the memory. For example, the compensation value detector detects the Vth and mobility deviation of the TFT by using a function of obtaining pixel current according to Vth and mobility, as described in US Patent Publication US 7,982,695, and offset for compensating the detected Vth. The value and the gain value for compensating for the mobility deviation are detected as the compensation value and stored in the memory in the form of a look-up table.

The compensation unit compensates the data input from the data processing unit 70 by using the compensation value stored in the memory and supplies the data to the data driver 30. For example, the compensator compensates the input data by multiplying the gain value with the input data and adding the offset value to the input data.

The compensation value detector and the compensation unit may be embedded in the timing controller 60, but may be provided as separate circuit components between the timing controller 60 and the data driver 30.

In addition, the timing controller 60 determines the peak luminance according to an average picture level (hereinafter referred to as APL) of the input data and supplies it to the gamma voltage generator 50 to reduce power consumption.

The gamma voltage generator 50 generates a gamma voltage set including a plurality of gamma voltages having different levels and supplies the gamma voltage set to the data driver 30. The gamma voltage generator 50 adjusts the maximum gamma voltage (gamma high potential power supply) in response to the peak luminance supplied from the timing controller 60, and divides the adjusted maximum gamma voltage through a resistor string to thereby provide a plurality of gamma. A gamma voltage set including the voltage is generated and output.

The data driver 30 converts digital data from the timing controller 60 into an analog data signal in response to a data control signal from the timing controller 60, and supplies the digital data to the plurality of data lines of the display panel 10. In this case, the data supply unit of the data driver 30 subdivides the gamma voltage set from the gamma voltage generator 50 into grayscale voltages corresponding to the grayscale values of the data, and then divides the digital data using the divided grayscale voltages. Convert to an analog data signal.

The sensing unit 20 described above with reference to FIGS. 3A to 3E of the data driver 30 is further provided. The sensing unit 20 divides each horizontal line HLi into five groups in response to the sensing channel selection signal SCS from the timing controller 60, and supplies sensing data to each subpixel for each divided group. After driving in the sensing mode, the characteristics of each subpixel are sensed and output to the timing controller 60.

The gate driver 8 sequentially drives a plurality of gate lines of the display panel 10 in response to a gate control signal from the timing controller 2. The gate driver 8 supplies a scan pulse of a gate-on voltage to each gate line in response to a gate control signal in a corresponding scan period, and supplies a gate-off voltage in the remaining period.

The display panel 10 includes a pixel matrix in which R / W / G / B subpixels connected to a data line, a gate line, a high potential power (ELVDD) line, and a low potential power (ELVSS) line are arranged in a matrix form. . Each subpixel has an OLED element and pixel circuits for driving the OLED element. The pixel circuit includes at least a switching transistor and a driving transistor and a storage capacitor. The switching transistor charges the storage capacitor with a voltage corresponding to the data signal from the data line in response to a scan pulse from the gate line, and the driving transistor controls the current supplied to the OLED element according to the voltage charged in the storage capacitor to the OLED. Adjust the amount of light emitted from the device. The amount of light emitted by the OLED element is proportional to the current supplied from the driving transistor.

In the above embodiment, only the OLED display device having the R / W / G / B subpixel has been described. However, the present invention is not limited thereto and may be applied to the OLED display device having the R / G / B subpixel.

As described above, the OLED display device and the driving method thereof according to the exemplary embodiment of the present invention divide each horizontal line HLi into a plurality of groups each having a different color and including spatially dispersed subpixels. By sensing the characteristics of the subpixels, when one group is driven in the sensing mode, the other group may be driven in the display mode.

Accordingly, the OLED display and the driving method thereof according to the present invention can sense the characteristics of the subpixels in the entire period of the vertical synchronization signal (each frame) irrespective of the display period. The period of time to be reduced can be significantly shortened. Accordingly, deterioration of the subpixels can be compensated in real time by fast sensing of the entire subpixels, or more accurate values can be sensed by repetitive sensing of the same subpixels to compensate for the deterioration of the subpixels.

In addition, the OLED display and the driving method thereof according to the present invention can minimize the deterioration of image quality by compensating for the luminance reduced by the subpixels driven in the sensing mode through data modulation of peripheral pixels.

Although illustrated and described in the specific embodiments to illustrate the technical idea of the present invention, the present invention is not limited to the same configuration and operation as the specific embodiment as described above, and various modifications do not depart from the scope of the present invention. It can be carried out within. Therefore, such modifications should also be regarded as belonging to the scope of the present invention, and the scope of the present invention should be determined by the claims below.

10: display panel 20: sensing unit
22: input channel selector 24: output channel selector
30: data driver 40: gate driver
50: gamma voltage generator 60: timing controller
70: data processing unit 72; Data input
74: sensing control unit 75: buffer
76: data mapping unit 78: luminance correction unit
80: data output unit

Claims (18)

A display panel having a structure in which a plurality of subpixels each having a different color in a plurality of horizontal lines is repeatedly arranged in a horizontal direction;
Built-in a sensing unit for dividing each horizontal line into a plurality of groups composed of a plurality of spatially distributed subpixels to sense characteristics of each subpixel for each group, and driving one group in the sensing mode in each horizontal line. And an organic light emitting diode (hereinafter referred to as OLED) display device having a data driver for driving the remaining groups in display mode. The method according to claim 1,
The sensing unit
Each horizontal line includes a first group of 5n-4th (n is a natural number) subpixels, a second group of 5n-3th subpixels, and a third group of 5n-2th subpixels. And a fourth group composed of 5n-1th subpixels, and a fifth group composed of 5nth subpixels to sense each group. The method according to claim 1,
And each of the plurality of groups includes subpixels of different colors constituting different pixels. The method according to claim 1,
The sensing unit senses by selecting one of the plurality of groups in response to a sensing channel selection signal,
And an order in which the plurality of groups are selected by the sensing channel selection signal is randomly changed every at least one horizontal line or at least one frame unit. The method according to claim 4,
Data for generating the channel selection control signal and calculating a luminance correction value by calculating the luminance reduced by the group driven in the sensing mode on each horizontal line, and using the luminance correction value to compensate for the luminance of the surrounding pixels. A processing unit;
The input data from the data processor is supplied to the data driver, the driving of the data driver is controlled, the data sensed from the subpixels of each group is input through the sensing unit, and the data is compensated using the sensed data. And a timing controller for calculating and storing a value and compensating for data to be supplied to the data driver with the stored data compensation value. The method according to claim 5,
The data processing unit
The luminance reduced by each group driven in the sensing mode is calculated in units of at least five pixels, and the calculated luminance value is distributed from the at least five pixels to neighboring pixels driven in the display mode, thereby obtaining luminance for each pixel. OLED display to calculate the compensation value. The method according to claim 6,
The data processing unit
Analyzing input data corresponding to the at least five pixels to map sensing data to subpixels driven in the sensing mode among the at least five pixels, and subpixels of the input data to subpixels driven in the display mode. OLED display for selectively changing and mapping pixel positions. The method according to claim 7,
The data processing unit
And dividing the luminance average value of two adjacent pixels in the at least five pixels into peripheral pixels driven in the display mode, and applying the luminance correction value of each of the peripheral pixels. The method according to claim 5,
And the timing controller repeats sensing of each subpixel through the sensing unit to calculate the data compensation value corresponding to each subpixel. The method according to any one of claims 1 to 9,
Each of the plurality of groups includes red, white, green and blue subpixels constituting different pixels or red, green and blue subpixels constituting different pixels. For a display panel having a structure in which a plurality of horizontal lines each having a different color and a plurality of subpixels are repeatedly arranged in the horizontal direction, each horizontal line is divided into a plurality of groups consisting of a plurality of spatially dispersed subpixels Dividing;
Sensing the characteristics of each subpixel for each of the divided groups in each of the horizontal lines, and driving the other group in the display mode when driving one group in the sensing mode on each of the horizontal lines. Driving method. The method according to claim 11,
Each horizontal line includes a first group of 5n-4th subpixels (n is a natural number), a second group of 5n-3th subpixels, and a third group of 5n-2th subpixels And a fourth group composed of 5n-1th subpixels, and a fifth group composed of 5nth subpixels. The method according to claim 11,
And each of the plurality of groups includes subpixels of different colors constituting different pixels. The method according to claim 11,
One of the plurality of groups is selected and sensed in response to a sensing channel selection signal,
And a method of selecting the plurality of groups by the sensing channel selection signal is randomly changed at least in one horizontal line or at least one frame unit. The method according to claim 14,
The luminance correction value is calculated by generating the sensing channel selection control signal and calculating the luminance reduced by the group driven in the sensing mode on each horizontal line, and compensating the luminance of the peripheral pixel with the luminance correction value. A data processing step;
The input data from the data processing step is supplied to the display panel through a data driver, and the data sensed from the subpixels of each group is input through a sensing unit built in the data driver, and the sensed data is used. And compensating for data to be supplied to the data driver. The method according to claim 15,
The data processing step
The luminance reduced by each group driven in the sensing mode is calculated in units of at least five pixels, and the calculated luminance value is distributed from the at least five pixels to neighboring pixels driven in a display mode for each pixel. A method of driving an OLED display device for calculating a luminance compensation value. The method according to claim 16,
The data processing step
Analyzing input data corresponding to the at least five pixels to map sensing data to subpixels driven in the sensing mode among the at least five pixels, and subpixels of the input data to subpixels driven in the display mode. And selectively changing and mapping pixel positions. The method according to claim 17,
The data processing step
And a luminance average value of two adjacent pixels in the at least five pixels is distributed to peripheral pixels driven in the display mode and applied as luminance correction values of each of the peripheral pixels.

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