KR20160041527A - Orgainc emitting diode display device - Google Patents

Abstract

The present invention relates to an organic light emitting diode (OLED) display device capable of enhancing compensation performance without an increase in a number of a bit of a compensation value. According to the present invention, the OLED display device comprises a data processing unit configured to process and perform dithering of a sensed first sensing value from each sub pixel and apply the same to a first compensation value, when the first compensation value is updated, and apply an average value of a first compensation value of a relevant sub pixel and first compensation values of adjacent sub pixels to data, when the OLED display device compensates for the data to be provided to each sub pixel.

Description

[0001] ORGANIC EMITTING DIODE DISPLAY DEVICE [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode (OLED) display device, and more particularly, to an OLED display device capable of improving a compensation capability without increasing the number of bits of a compensation value.

2. Description of the Related Art Recently, flat panel display devices that display images using digital data include liquid crystal displays (LCDs) using liquid crystals, OLED display devices using OLEDs, electrophoretic displays (EPDs) using electrophoretic particles ).

Of these, OLED display devices are self-luminous devices that emit organic light-emitting layers by recombination of electrons and holes, and are expected to be a next-generation display device because of their high luminance, low driving voltage, and ultra thin films.

Each of the plurality of pixels or subpixels constituting the OLED display device includes at least an OLED element composed of an organic light emitting layer between the anode and the cathode, at least a switching thin film transistor (TFT) and a storage capacitor And a pixel circuit including a driving TFT.

The OLED display has a problem that the luminance is not uniform due to the difference in driving characteristics for each sub-pixel due to various causes. For example, there are differences in sub-pixel-by-sub-pixel driving characteristics such as a threshold voltage (hereinafter referred to as Vth) and mobility of the driving TFT due to process variations and the like, The driving characteristics for each subpixel are varied due to deterioration or the like, so that the current for each subpixel is not uniform with respect to the same data, resulting in non-uniformity of luminance. In order to solve this problem, an OLED display device uses an external compensation method for sensing driving characteristics of each sub-pixel and compensating data using sensed characteristic information.

Specifically, the current Ids of the driving TFT is expressed by the following equation (1).

&Quot; (1) "

Ids =? (Vgs - Vth) ²

Here,? Is a proportional coefficient including the mobility and channel width (W) / length (L) component of the driving TFT, Vgs is the gate-source voltage of the driving TFT, and Vth is the threshold voltage of the driving TFT. Since Vth and? Are different for each driving TFT and Vth and? Are varied depending on the elapsed time of driving time and the like, the OLED display device uses an external compensation method for sensing and compensating for Vth and? Of each driving TFT.

The compensation value applied to each subpixel can compensate more accurately as the number of bits increases, but there is a limit to increase the number of bits due to the capacity limitation of the memory. Accordingly, there is a problem that image quality is deteriorated due to insufficient compensation capability due to a lack of compensation resolution that each compensation value of each subpixel can compensate.

For example, there is a problem that the level difference between consecutive compensation values is recognized as a boundary line due to the lack of resolution of the compensation value due to the limitation of the number of bits, thereby deteriorating the image quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an OLED display device capable of improving a compensation capability without increasing the number of bits of a compensation value.

According to an aspect of the present invention, there is provided an OLED display including: a display panel including a plurality of sub-pixels having different colors; A memory for storing a first compensation value for compensating mobility of each subpixel and a second compensation value for compensating a threshold voltage of each subpixel; When updating the first compensation value, the first sensing value sensed from each subpixel is subjected to a post-processing dithering process to apply the first sensing value to the first compensation value, and the first and second compensation values are applied to each subpixel And a data processing unit for applying the average value of the first compensation values of the subpixels adjacent to the subpixel to the data when the data is compensated.

The data processing unit includes a compensation unit and a data driver.

The compensation unit compensates the voltage data by applying the average value and the second compensation value when the display mode and the sensing mode are in operation, and supplies the compensated voltage data to the corresponding subpixel of the display panel through the data driver.

When the sensing unit is in the sensing mode, the signal output from the sub-pixel is sensed by the data driver to detect the first sensing value, the difference between the first sensing value and the reference value from the memory is calculated, And adds the dither value selected according to the position of the corresponding subpixel to the difference value, thereby dithering the difference value. Then, the compensation unit computes the dithered difference value with a predetermined proportional coefficient and applies it to the first compensation value.

The compensation unit reads the first compensation values of the corresponding subpixel and the surrounding subpixels included in the predetermined pixel region from the memory, calculates an average value, and calculates a gain value by an operation using the average value and the compensation coefficient from the memory. The compensation unit compensates the data to be supplied to the corresponding subpixel using the gain value, and further compensates using the second compensation value from the memory.

If the difference between the first compensation value of the corresponding subpixel and the first compensation value of the neighboring subpixels is equal to or greater than a preset reference value, the compensating unit compensates the data by applying the first compensation value of the corresponding subpixel instead of the average value.

The reference value for the first sensing value stored in the memory is a first sensing average value obtained by averaging the initial first sensing value for the subpixels of the display panel by color. The average value for the first compensation values is an average value for the first compensation values of the neighboring subpixels having the same color as the corresponding subpixel.

The OLED display according to the present invention may dither the stored compensation values and store the sensed compensation values to reduce the level difference of the compensation values spatially.

In addition, the OLED display according to the present invention can prevent the level difference of the compensation value from being recognized as a boundary by smoothing the compensated value read from the memory during compensation and applying the smoothed value to the image data.

Therefore, the OLED display according to the present invention can increase the resolution of the compensation value without increasing the number of bits of the compensation value, thereby improving the compensation capability and improving the image quality.

1 is a block diagram schematically illustrating an OLED display according to an embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram illustrating the R / W / B / G subpixel structure shown in FIG.
3 is a diagram illustrating a real-time sensing period in an OLED display according to an exemplary embodiment of the present invention.
4 is a block diagram specifically showing an internal configuration of the image processing unit shown in Fig.
FIG. 5 is a diagram showing comparison of? Correction values before and after application of dithering according to an embodiment of the present invention.
FIG. 6 is a diagram showing a comparison of the a compensation values before and after the smoothing application according to the embodiment of the present invention.
FIG. 7 is a view illustrating a sensing method and a compensation method of an OLED display according to an exemplary embodiment of the present invention.
8 is a view showing a comparison result of the a compensation result of the OLED display according to the prior art and the embodiment of the present invention.
FIG. 9 is a graph illustrating a comparison result of? Compensation using only dither and smoothing in an OLED display according to an exemplary embodiment of the present invention. Referring to FIG.

1 is a block diagram schematically illustrating an OLED display according to an embodiment of the present invention.

1 includes a timing controller 10 including a control signal generating unit 100 and an image processing unit 200 and a display unit including a memory M, a data driver 20, a gate driver 30, Panel 40 and the like. Here, the image processing unit 200 and the data driver 20 can be represented by a data processing unit.

1, the image processing unit 200 may be built in the timing controller 10 and may be constituted by one IC, or may be constituted by a separate IC separated from the timing controller 10 (not shown). In this case, the timing controller 10 May be connected between the image processing section 200 and the data driver 20. [ Hereinafter, a case where the timing controller 10 includes the image processing unit 200 will be described as an example.

In the memory M, compensation information set according to the characteristics of each subpixel is stored for a uniform current of each subpixel. The compensation information includes a Vth compensation value for compensating the Vth of the driving TFT of each subpixel and an a compensation value (? Cmp) for compensating the? Of the driving TFT.

The compensation information (Vth,? _Cmp) is preset in the memory (M) based on a sensing value obtained by sensing the characteristics (Vth,?) Of each subpixel before shipment. After the product is shipped, the compensation information (Vth,? _Cmp) stored in the memory (M) is updated by sensing the characteristics of each subpixel again through the sensing mode for each desired drive time. The sensing mode is executed every at least one desired driving time including the power-on boot time, the power-off end time, the blanking period of each frame, etc. and the compensation information (Vth, a_cmp) stored in the memory M is updated .

For example, since α is affected by temperature and light, which are external environmental conditions, it is sensed at least one of the boot time at power-on and the blanking period of each frame, and the α compensation value α_cmp May be updated. The Vth compensation value Vth stored in the memory M may be updated by sensing at least one of the blanking period and the power-off time end time of each frame.

Further, in the memory M, an alpha compensation value D used together with the alpha compensation value alpha_cmp is preset and stored for each color and gradation when correcting the voltage data, and the alpha compensation value alpha_cmp is updated The alpha sensing average value alpha_avg is preset and stored for each color as a reference value used at the time of printing. The? compensation coefficient D is optimized in accordance with the voltage data Vdata of each gradation for each color by using a characteristic in which? varies according to the gradation, and is set in advance and serves to prevent? and compensation.

In the timing controller 10, the control signal generator 100 generates data for controlling the timing of driving the data driver 20 and the gate driver 30 using a plurality of timing signals input to an external system (not shown) And outputs the generated control signal and gate control signal to the data driver 20 and the gate driver 30. [ For example, the control signal generator 100 controls the driving timing of the data driver 20 using a plurality of timing signals, such as a clock signal, a data enable signal, a horizontal synchronizing signal, a vertical synchronizing signal, A plurality of data control signals including a source start pulse, a source shift clock, a source output enable signal, and the like, and a plurality of gates including a gate start pulse and a gate shift clock for controlling the driving timing of the gate driver 30 And generates and outputs a control signal.

In the timing controller 10, the image processing unit 200 compensates the image data input from the external system using the compensation information of the memory M, and outputs the compensated data to the data driver 20. [ The image processing unit 200 processes the sensed information of each sub-pixel sensed by the data driver 20 according to a predetermined computation, converts it into compensation information, and updates compensation information of the memory M. [

In particular, the image processing unit 200 stores the compensation information in the memory M by applying a dithering process when updating the compensation information, smoothing the compensation information read from the memory M when compensating the data, To be applied. Accordingly, the compensation information detected from the sensing information is spatially dispersed through the dithering process and is stored in the memory M, and the compensation information from the memory M is smoothed and applied to the data, Can be reduced. Therefore, the resolution of the compensation information can be increased without increasing the number of bits of the compensation information.

The compensation information of each subpixel includes a Vth compensation value and an? Compensation value. For example, when the compensation information of each subpixel uses 16 bits, 10 bits are used as the Vth compensation value, and the remaining 6 bits are used as the a compensation value. Accordingly, the Vth compensation value using 10 bits can compensate Vth with 1024 levels (0 to 1023), while the α compensation value using 6 bits is compensated for 64 levels (0 to 63) The compensation resolution of the compensation value is insufficient. In order to solve this problem, the image processing unit 200 can increase the compensation resolution of the a compensation value without increasing the number of bits by applying the dithering process and the smoothing process to the a compensation value. The image processing unit 200 may or may not apply the dithering processing and the smoothing processing to the Vth compensation value.

In order to reduce power consumption, the image processing unit 200 determines the peak luminance according to the image of each frame using the input image data, calculates the total current, determines the high-potential voltage according to the peak luminance and the total current And supplies it to the data driver 20.

When the R / G / B data is input as image data to the external system, the image processing unit 200 converts the R / G / B data into R / G / B / W data through a predetermined operation, It can be used for processing.

The data driver 20 converts the data supplied from the timing controller 10 into analog data signals using the data control signals supplied from the timing controller 10 in the display mode and the sensing mode and supplies them to the display panel 40 do. The data driver 20 converts the digital data into an analog data voltage using a gamma voltage set from a built-in gamma voltage generator (not shown).

The data driver 20 converts the digital high-potential voltage supplied from the current controller 210 of the timing controller 10 into an analog high-potential voltage in the display mode and the sensing mode, or converts the analog high- And supplies it to the display panel 40 by adjusting the voltage. The gamma voltage generator divides the analog high voltage by a resistor string to generate a gamma voltage set including a plurality of gamma voltages.

The data driver 20 converts the voltage (or current) sensed through the sensing line from each sub-pixel of the display panel 50 in the sensing mode into a digital sensing value and supplies the digital sensing value to the timing controller 10. As the sensing line for outputting the current including the characteristics of each subpixel to the data driver 20, any one of a data line, a reference line, and a power supply line connected to each subpixel may be used.

The data driver 20 includes at least one data drive IC and is mounted on a circuit film such as a tape carrier package (TCP), a chip on film (COF), or a flexible printed circuit (FPC) (Tape Automatic Bonding) method, or on a non-display area of the display panel 40 by a COG (Chip On Glass) method.

The gate driver 30 drives the plurality of gate lines of the display panel 40 using the gate control signal supplied from the timing controller 10. [ The gate driver 30 supplies the gate-on voltage to the respective gate lines using the gate control signal, and supplies the gate-off voltage during the remaining periods. The gate driver 30 may receive a gate control signal directly from the timing controller 10 or may receive a gate control signal from the timing controller 10 via the data driver 20. [

The gate driver 30 is composed of at least one gate drive IC and mounted on a circuit film such as TCP, COF, FPC or the like to be attached to the display panel 40 in a TAB manner or a non-display Area. ≪ / RTI > Alternatively, the gate driver 30 may be formed in a non-display region of the TFT substrate together with the TFT array formed in the pixel array of the display panel 40, thereby forming a gate in panel (GIP) type built in the display panel 40 .

The display panel 40 includes a pixel array in the form of a matrix. Each pixel of the pixel array is comprised of R / W / B / G subpixels. Alternatively, each pixel may comprise R / G / B subpixels.

FIG. 2 is an equivalent circuit diagram illustrating the R / W / B / G subpixel structure shown in FIG.

The R / W / B / G subpixels are respectively connected to the data lines DL1 to DL4, share one gate line GL1, and share one reference line RL. Alternatively, the R / W / B / G subpixels may share a pair of gate lines or may be connected to different reference lines, respectively, although these are not shown. The pair of data lines DL1 and DL2 are arranged side by side between the R / W subpixels and the other pair of data lines DL3 and DL4 are arranged side by side between the B / G subpixels.

One power supply line PL disposed on the left side of the R subpixel is commonly connected to the R / W subpixels, and another power supply line PL disposed on the right side of the G subpixel is commonly connected to the B / G subpixel And supplies a high potential voltage (EVDD).

Each of the R / W / B / G subpixels includes an OLED element and first and second switching TFTs ST1 and ST2, a driving TFT DT and a storage capacitor Cst for independently driving an OLED element And a pixel circuit.

The first and second switching TFTs ST1 and ST2 and the driving TFT DT may be formed of an amorphous silicon (a-Si) TFT, a poly-Si TFT, an oxide TFT, Etc. may be used.

The OLED element has an anode connected to the driving TFT (DT), a cathode connected to the low potential voltage (EVSS), and a light emitting layer between the anode and the cathode. The anode is formed independently for each subpixel, but the cathode is formed so that all the subpixels share. The light emitting layer may include a hole injecting layer, a hole transporting layer, an organic light emitting layer, an electron transporting layer, and an electron injecting layer sequentially stacked between the anode and the cathode, and may include a functional layer for improving the light emitting efficiency and / . In the OLED element, when a positive bias is applied between the anode and the cathode, electrons from the cathode are supplied to the organic light emitting layer via the electron injection layer and the electron transport layer, and holes from the anode are injected into the organic light emitting layer via the hole injection layer and the hole transport layer . Accordingly, the organic light emitting layer emits fluorescence or phosphorescent material by recombination of the supplied electrons and holes, thereby generating light proportional to the amount of current supplied from the driving TFT DT.

The first and second switching TFTs ST1 and ST2 are simultaneously driven by the scan signal of one gate line GL1 to drive the data voltage Vdata from the corresponding data line DL and the data voltage Vdata from the corresponding reference line RL And supplies the reference voltage Vref to the gate and the source node of the driving TFT DT, respectively. Alternatively, the first and second switching TFTs ST1 and ST2 may be driven by different gate lines, respectively. The second switching TFT ST2 is further used as a path for outputting the current from the driving TFT DT to the reference line RL in the sensing mode.

The storage capacitor Cst is connected between the gate node and the source node of the drive TFT DT. The storage capacitor Cst is connected between the data voltage Vdata supplied to the gate node through the first switching TFT ST1 and the reference voltage Vref supplied to the source node through the second switching TFT ST2 Vdata-Vref) and supplies it as the driving voltage Vgs of the driving TFT DT.

The driving TFT DT controls the current supplied from the high potential voltage supply line PL in accordance with the driving voltage Vgs supplied from the storage capacitor Cst so that the current Ids proportional to the driving voltage Vgs ) To the OLED element to emit the OLED element.

Since the second switching TFT ST2 of each of the R / W / B / G subpixels shares one reference line RL, the characteristics of each of the R / W / B / May be sensed via the shared reference line RL. For example, when sensing the characteristics of one of the R, W, B, and G subpixels, the sensing data voltage is supplied to the subpixel, Black data voltage) may be supplied and turned off.

The high potential voltage (EVDD) supplied to the display panel 40 through the data driver 20 is varied by the timing controller 10 in accordance with the brightness of the input image, so that power consumption can be reduced.

3 is a diagram illustrating a real time sensing period of the OLED display according to the present invention.

Referring to FIG. 3, each frame includes a writing period and a blanking period. In each lighting period, image data is written to each subpixel in a line sequential manner. The characteristic of the subpixels for one horizontal line in each blanking period is sensed, and the compensation information of the memory M is updated.

For example, in the blanking period of the n-frame, the characteristics of the n-line sub-pixels are sensed to update the a-compensation value (? _Cmp) of the corresponding sub-pixels in the memory M, (N + 2) -th line in the blanking period of the (n + 2) -th frame by sensing the characteristics of the subpixels in the line M) of the corresponding subpixels.

On the other hand, in each blanking period, subpixels of the horizontal line can be separated for each color and sensed. For example, when the display panel has N horizontal lines, R sub-pixels are sensed in horizontal line units every N blanking periods, and W sub-pixels are arranged in units of horizontal lines in every N blanking periods And then sense the B sub-pixels in the same way, and then sense the G sub-pixels.

FIG. 4 is a block diagram specifically showing an internal configuration of the image processing unit 200 shown in FIG.

The image processing unit 200 shown in FIG. 4 includes a current control unit 210, a data conversion unit 220, a compensation unit 230, and the like. In addition, the image processing unit 200 includes a four-color conversion unit (not shown) for converting the R / G / B data input from the external system into R / G / B / W data through a predetermined calculation, May also be included.

The current controller 210 determines the peak luminance and the total current of each frame by using the image data input from the external system, determines a high potential voltage according to the peak luminance and the total current, and supplies the determined high luminance voltage to the data driver 20.

The current controller 210 detects the average picture level (APL) indicating the number of pixels having peak luminance in each frame, i.e., the area occupied by white pixels in one screen, using the gray-scale data as the input image data , And determines the peak luminance according to the detected APL. The current controller 210 determines the peak luminance corresponding to the APL using an LUT in which the peak luminance for the APL is previously stored in an internal memory (not shown). For power saving, peak luminance is determined to be inversely proportional to APL. That is, the larger the APL is (the bright image), the smaller the peak luminance is determined, and the larger the APL (the darker the image), the larger the peak luminance is determined.

In addition, the current controller 210 calculates the total current per frame by summing the current values for the gray-scale data using the LUT in which the current values for the gray-scale data per R / G / B / W are previously stored in the internal memory. The current controller 210 determines the final peak luminance by adjusting the peak luminance determined according to the APL according to the total current, determines a high potential voltage corresponding to the final peak luminance, and outputs the determined high peak voltage to the data driver 20. In addition, the current controller 210 outputs the gradation data to the data converter 220.

The data converter 220 converts the gradation data, which is image data input from the current controller 210, into voltage data and outputs the voltage data to the compensator 230. Specifically, the data converting unit 220 converts the R / G / B / W gradation data into an internal memory (not shown) using the LUT in which the voltage data for the gradation data for each R / G / R / G / B / W voltage data and outputs it to the compensation unit 230. Since the compensation information stored in the memory M, i.e., the Vth compensation value and the a compensation value a_cmp are all voltage values, image data which is grayscale data is converted into voltage data for compensation using them.

The compensation unit 230 compensates the voltage data input from the data conversion unit 220 using the compensation information stored in the memory M and outputs the compensated voltage data to the data driver 20. [ The compensation unit 230 updates the compensation information of the memory M using the sensing value sensed from each sub pixel of the display panel 40 through the data driver 20. [ In particular, the compensation unit 230 applies a dithering process when storing the compensation information, and applies a smoothing process when compensating the data. The compensating unit 230 can apply the dithering process and the smoothing process only to the a compensation value for which the number of bits is smaller than the Vth compensation value in the compensation information.

Specifically, the compensation unit 230 includes a compensation value detection unit 232 and a compensation value application unit 324.

In the compensating unit 230, the compensation value detecting unit 232 detects at least one of the Vth sensing value and the? Sensing value? _Sen of the driving TFT of each subpixel from the sensing information sensed through the data driver 20 , The Vth compensation value Vth of the memory M is updated using the Vth sensing value and the a compensation value α_cmp is updated using the α sensing value α_sen.

The compensation value detection unit 232 detects the Vth sensing value from the sensing information of each subpixel supplied from the data driver 20 and converts the Vth sensing value into a Vth compensation value of a compensable unit through a predetermined calculation, The Vth compensation value Vth of the Vth compensation value Vth is updated.

In particular, the compensation value detector 232 detects the alpha sensing value from the sensing information of each subpixel supplied from the data driver 20, processes the alpha sensing value and converts the alpha sensing value into the alpha compensation value, And stores it in the memory (M).

Specifically, as shown in the following Equation 2, the compensation value detector 232 detects the difference between the α-sensing value α_sen detected from the sensing information of each sub-pixel and the α-average value α_avg read from the memory M as a reference value, And calculates the value DELTA alpha.

&Quot; (2) "

Δα = α_sen - α_avg

Δα '= Δα + D

α_cmp '= α_cmp + Δα' / γ

Also, as shown in Equation (2), the compensation value detector 232 dithers the difference value? To spatially disperse the difference value?. For example, as shown in FIG. 5 (b), the compensation value detector 232 may use a dither pattern in which different dither values (0, 0.25, 0.5, 0.75) are distributed so that the same values are not adjacent to each other (D) according to the position of the corresponding subpixel, and adds the difference value [Delta] [alpha] to the selected dither value (D), thereby dithering the difference value [Delta] [alpha].

The compensation value detector 232 updates the compensation value ?_cmp of the memory M using the dithered difference value? 'As shown in Equation (2). The compensation value detection unit 232 corrects the a compensation value a_cmp by adding the dithered difference value? 'And the a compensation value a_cmp read from the memory M, and outputs the corrected a compensation value a_cmp' ) To the memory M to update the a compensation value alpha_cmp. At this time, the compensation value detector 232 calculates the compensation value?? '/? To be actually used by calculating the ratio?' /? Between the dithering difference value? 'And the predetermined proportional coefficient? /?) and then updates the? compensation value? _cmp by adding the correction value ?? '/? to the? compensation value? _cmp. The predetermined proportional coefficient? Varies depending on the characteristics (e.g., sensing voltage, sensing period, etc.) of the product model. For example, the proportional coefficient γ is 1 when Δα 'changes by eight when the α compensation value α_cmp changes by one.

5A and 5B, in contrast to the actual correction value? /? Table of the prior art calculated without the dithering process of the difference value? As shown in FIG. 5A, It can be seen that the level difference between the correction values in the actual correction value ?? '/? Table of the present invention calculated by dithering the difference value ?? as shown in FIG. 5 (b) decreases.

Thus, without increasing the number of bits of the a compensation value a_cmp stored in the memory M, the level difference of the continuous a compensation value a_cmp is spatially dispersed and reduced by dithering the difference value? Compensation resolution is increased.

The compensation value application unit 234 in the compensation unit 230 applies the compensation information of each subpixel read from the memory M to the voltage data of each subpixel inputted from the data conversion unit 220 Compensates the voltage data and outputs it to the data driver 20. The compensation value application unit 234 compensates the voltage data Vdata in the display mode and the sensing mode and outputs the compensation data to the data driver 20. [ The compensation value application unit 234 applies smoothing processing to the voltage compensation data (? _Cmp) among compensation information (Vth,? _Cmp) of each subpixel.

Meanwhile, the compensation value application unit 234 may apply the Vth compensation value to the voltage data by smoothing processing. For convenience of explanation, the smoothing process for the a compensation value (? _Cmp) will be described below as an example.

Specifically, the compensation value application unit 234 applies the compensation value ?_cmp of the corresponding subpixel corresponding to the voltage data input from the data conversion unit 220 and the compensation value? (a_cmp) of peripheral subpixels of the same color included in a pixel region of a predetermined number of pixels (for example, k is a natural number) is read from the memory M and smoothed by averaging, and the averaged a compensation value Compensates the voltage data.

For example, as shown in FIG. 6 (b), the a compensation value (? _Cmp) of the corresponding subpixel included in the 3 × 3 pixel region and the a compensation values (? And uses the average compensation value ?_cmp 'as the? Compensation value ?_cmp' of the corresponding subpixel.

In order to remove the defective subpixel, if the difference between the corresponding? Compensation value (? _Cmp) and the surrounding? Compensation values (? Cmp) included in the pixel region is greater than a preset reference value, , And uses the corresponding? Compensation value (? _Cmp) without smoothing processing.

The compensation value application unit 234 performs a predetermined operation on the smoothed a compensation value alpha_cmp and the alpha compensation coefficient D read from the memory M to calculate a gain value g .

&Quot; (3) "

g = D x (alpha_cmp '- 1) + 1

Vdata '= gxVdata + Vth

Then, the voltage data (Vdata) is compensated using the calculated gain value (g) and the Vth compensation value (Vth) of the corresponding sub pixel read from the memory (M) And outputs the data (Vdata ') to the data driver 20. The compensation value application unit 234 compensates the voltage data Vdata by multiplying the voltage data Vdata by the gain value g and then adding the Vth compensation value Vth.

6A and 6B, in contrast to the prior art a compensation value? _Cmp, which does not consider the? Compensation values? _Cmp of neighboring subpixels as shown in FIG. 6A, As shown in FIG. 6 (b), it can be seen that the level difference from the adjacent compensation values is reduced in the smoothing-processed? Compensation value? - cmp in consideration of the? Compensation values?

Therefore, the compensation resolution can be increased without increasing the number of bits of the compensation value by further decreasing the stepwise continuous a-compensation values (? _Cmp) difference by the smoothing processing of the compensation value a_cmp.

FIG. 7 is a flowchart illustrating a method and a method for real-time sensing of an OLED display according to an exemplary embodiment of the present invention.

The real time sensing method shown in Fig. 7 (a) and the image driving compensation method shown in Fig. 7 (b) will be described with reference to the OLED display device shown in Figs. 1 and 4. Fig.

In the sensing mode, in step S2, the compensating unit 230 smoothes the a compensation value? Cmp of the corresponding subpixel considering the compensation values? Cmp of the neighboring subpixels. In other words, the compensating unit 230 averages the? Compensation values? _Cmp of the surrounding subpixels of the same color as the corresponding subpixel included in the specific pixel region read from the memory M, (? _cmp ') is used as the a compensation value of the corresponding subpixel.

In step S4, the compensating unit 230 uses the smoothing processed? Compensation value ?_cmp 'and the Vth compensation value Vth of the corresponding subpixel read from the memory M to calculate the sensing voltage data Vdata ), And outputs the compensated voltage data (Vdata ') to the data driver 20.

The compensation unit 230 reads the a compensation coefficient D corresponding to the sensing voltage data Vdata from the memory M and outputs the smoothed a compensation value a_cmp ' The gain value g is calculated by performing an operation as in Equation 2 and the sensing voltage data Vdata is calculated using the calculated gain value g and the Vth compensation value Vth read from the memory M, And supplies the compensated voltage data (Vdata ') to the data driver 20.

In step 6 (S6), the data driver 20 converts the compensated sensing voltage data Vdata 'into an analog signal and supplies the analog signal to each subpixel of the display panel 40, 20 to sense the characteristics of each subpixel. The data driver 20 senses the voltage (or current) output through the sensing line from each subpixel of one horizontal line supplied with the sensing voltage data Vdata ', converts the sensing value into digital data, (230). As the sensing line, any one of a data line, a reference line, and a power supply line connected to each subpixel in the display panel 40 is used.

In step 8 (S8), the compensating unit 230 detects the? Sensing value? _Sen from the sensing value supplied from the data driver 20 and outputs the? Average value read from the memory M (? _avg), dithering the difference value?, and correcting the? compensation value ?_cmp read from the memory M by using the dithered difference value? ' And stores it in the memory M to update the a compensation value a_cmp.

In the image display mode, in step 12 (S12), the compensating unit 230 obtains the? Compensation value ?_cmp of the corresponding subpixel and the? Compensation values? ), And uses the average compensation value (? _Cmp ') as the a compensation value of the corresponding subpixel.

In step 14 (S4), similarly to step 4 (S4) described above, the compensation unit 230 stores the smoothed? Compensation value ?_cmp 'and the? Compensation coefficient D read from the memory M The gain value g is calculated by using the equation (2), the display voltage data Vdata is compensated by using the gain value g and the Vth compensation value Vth read from the memory M, (Vdata ') is supplied to the data driver 20.

The data driver 20 converts the voltage data Vdata 'supplied from the compensating unit 230 to an analog signal and supplies the analog data to each subpixel in step 16 (S16), whereby the display panel 40 displays an image.

FIG. 8 is a graph comparing a result obtained by compensating? According to the prior art and a result compensated according to an embodiment of the present invention.

8 (a) shows the levels of the initial a compensation value in color, and it can be seen that the initial a compensation values of the sub pixels are not uniform.

8B shows a result obtained by sensing α of each subpixel according to the prior art. Even though the difference between the initial α compensation values is compensated for, but the compensating capability is insufficient, contour lines due to the difference in levels of the α compensation values are still It can be seen that it remains.

8 (c) shows the a compensation values updated through the dithering process according to the embodiment of the present invention. By contrast with the initial a compensation values shown in Fig. 8 (a) It can be seen that the contour line is blurred.

8 (d) shows a compensation result obtained by applying smoothing processing to the a compensation value updated by the dithering process according to the embodiment of the present invention. As shown in Fig. 8 (b) It can be seen that the contour line is not recognized.

FIG. 9 is a diagram showing a result of using only one of the dithering and the smoothing processing on the a compensation value in the embodiment applied to the present invention.

9A is a representation of updated? Compensation values through a dithering process as shown in FIG. 8C, and FIG. 9B is a view showing a compensation obtained by applying an? Compensation value updated by a dithering process as shown in FIG. As a result, it can be seen that contour lines still remain only by the dithering process.

FIG. 9 (c) shows the a compensation values updated according to the prior art without the dithering process, and FIG. 9 (d) shows the compensation results obtained by smoothing the a compensation value of the prior art shown in FIG. It can be seen that contour lines still remain even with the smoothing process alone.

Therefore, the OLED display according to the present invention can increase the resolution of the compensation value without increasing the number of bits of the compensation value by updating the compensation value using the dithering process, smoothing the compensation value, and applying the smoothing process to the data Therefore, the compensation ability is improved and the image quality can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of illustration, Can be carried out within a range. Accordingly, such modifications are deemed to be within the scope of the present invention, and the scope of the present invention should be determined by the following claims.

10: timing controller 20: data driver
30: gate driver 40: display panel
100: control signal generation unit 200: image processing unit
210: current control unit 220:
230: compensation section 232: compensation value detection section
238: compensation value application part M: memory

Claims (5)

A display panel including a plurality of sub-pixels having different colors,
A memory for storing a first compensation value for compensating mobility of each subpixel and a second compensation value for compensating a threshold voltage of each subpixel;
A first sensing value is sensed from each subpixel and applied to the first compensation value, and the first compensation value and the second compensation value are applied to each of the subpixels to update the first compensation value, And a data processor for applying to the data an average value of the first compensation values of the subpixels adjacent to the first compensation value of the corresponding subpixel when compensating the data to be supplied to the pixel, OLED) display device. The method according to claim 1,
Wherein the data processing unit includes a compensation unit and a data driver,
The compensation unit
Compensating the voltage data by applying the average value and the second compensation value in a display mode and a sensing mode,
Supplying the compensated voltage data to the corresponding sub-pixel of the display panel through the data driver,
Wherein the first sensing value is detected by sensing the signal output from the corresponding subpixel through the data driver when the sensing mode is selected,
Calculating a difference value between the first sensing value and a reference value from the memory,
A difference value is added to the difference value by adding any one of the dither values selected according to the position of the corresponding subpixel in the dither pattern in which different dither values are distributed and arranged,
And calculates a dithered difference value with a predetermined proportional coefficient to apply the calculated difference value to the first compensation value. The method of claim 2,
The compensation unit
Calculating a mean value by reading first compensation values of the corresponding subpixel and neighboring subpixels included in a predetermined pixel region from the memory,
Calculating a gain value by an operation using an average value for the first compensation values and a compensation coefficient from the memory,
Compensates data to be supplied to the corresponding subpixel using the gain value, and further compensates the data using the second compensation value from the memory. The method of claim 3,
The compensation unit
If the difference between the first compensation value of the corresponding subpixel and the first compensation value of the neighboring subpixels is equal to or greater than a preset reference value, the first compensation value of the corresponding subpixel is used instead of the average value, And the OLED display device. The method of claim 3,
Wherein the reference value for the first sensing value stored in the memory is a first sensing average value obtained by averaging an initial first sensing value for subpixels of the display panel,
Wherein an average value of the first compensation values is an average value of first compensation values of neighboring subpixels having the same color as the corresponding subpixel.

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