Non-uniformity compensation apparatus and method and data processing circuit for non-uniformity compensation

Abstract

This invention provides an unevenness compensation apparatus and method, as well as a data processing circuit for unevenness compensation. The data processing circuit according to an embodiment may include a receiving circuit configured to receive image data comprising grayscale values ​​associated with pixels arranged in a display panel. The data processing circuit may include a compensation circuit configured to calculate a final compensation value by multiplying representative compensation values ​​of each region by a global gain, and to generate converted image data. The data processing circuit may include a memory storing representative compensation values ​​associated with grayscale values ​​of each region of the display panel, and may include a transmission circuit configured to transmit the converted image data to a data driving circuit.

Description

Technical Field

[0001] This disclosure relates to a non-uniformity compensation method and data processing circuit of a non-uniformity compensation device, and to a non-uniformity compensation device and data processing circuit for detecting and compensating for non-uniformity in a display panel. Background Technology

[0002] Various types of panels, such as liquid crystal display (LCD) panels and organic light-emitting diode (OLED) panels, can be used in display devices, and the panels can be controlled by the data processing circuitry of the display device.

[0003] Multiple pixels are arranged in the panel, and the data processing circuit can control the light-emitting elements (such as organic light-emitting diodes (OLEDs)) of each pixel, or can control the open elements (such as liquid crystals (LCs)) to control the brightness of each pixel.

[0004] The display panel driver can control the brightness of the image displayed in the control panel by changing the data voltage supplied to each pixel based on the grayscale value.

[0005] Although the same data voltage is provided to each pixel, brightness differences may occur between pixels in the panel due to various internal and external factors (such as faults and defects in the manufacturing process of the display panel, design flaws, changes in physical characteristics during panel operation, etc.).

[0006] If the difference in brightness caused by the change in the characteristics of some pixels in the display panel relative to the characteristics of adjacent pixels is defined as a mura defect, then the pixels or areas of the panel with the mura defect can be detected and compensated.

[0007] To detect unevenness in a display panel, the pixels of the display panel are operated on the same grayscale, and images of them are captured. Patterns such as spots or images that are not displayed in the same color can be detected as unevenness.

[0008] The desired technology is one that compensates for unevenness in the image displayed across the entire panel by identifying its brightness, color, etc., in order to uniformly maintain the characteristics of the screen.

[0009] However, the memory capacity required to store the characteristics of all the pixels in the entire panel in memory in order to compensate for unevenness in the display panel, or to calculate the unevenness compensation value through complex operations in order to determine the characteristics of unevenness, may be too high, which is a drawback. Summary of the Invention

[0010] In this context, one aspect of the embodiments of this disclosure is to provide a non-uniformity compensation device and a data processing circuit that can efficiently utilize memory by determining non-uniformity for each block based on image data and using representative compensation values ​​for each block.

[0011] Another aspect of the embodiments of this disclosure is to provide a non-uniformity compensation device and a data processing circuit that can efficiently utilize memory by calculating a single global gain and calculating a final compensation value.

[0012] To this end, a first embodiment may provide a data processing circuit, comprising: a receiving circuit configured to receive image data including grayscale values ​​associated with pixels arranged in a display panel; a memory storing representative compensation values ​​associated with the grayscale values ​​of each block of the display panel; a compensation circuit configured to calculate a final compensation value by multiplying the representative compensation value of each block by a global gain and to generate converted image data; and a transmission circuit configured to transmit the converted image data to a data driving circuit.

[0013] A second embodiment may provide an unevenness compensation device, comprising: a receiving circuit configured to obtain a plurality of brightness values ​​corresponding to a plurality of grayscale values ​​associated with a single block of a display panel; and a calculation circuit configured to calculate a compensation value for the grayscale values ​​to resolve unevenness caused by the difference between a target brightness value and the brightness values, and to calculate a final compensation value by generating representative compensation values ​​for each block.

[0014] A third embodiment may provide an unevenness compensation method, comprising: calculating a brightness compensation value for a plurality of pixels in an uneven block in image data; using the brightness compensation value for the plurality of pixels to calculate a representative compensation value for each uneven block; calculating a global gain for each gray level based on a single uneven block; and generating a final unevenness compensation value by multiplying the representative compensation value for each uneven block by the global gain.

[0015] As described above, according to embodiments of the present disclosure, a data processing circuit and a method for non-uniformity compensation of the data processing circuit are provided, which can improve the accuracy of non-uniformity compensation and minimize the memory capacity used for non-uniformity compensation. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the configuration of a display device according to an embodiment;

[0017] Figure 2 This is a diagram illustrating the signal flow of the non-uniformity compensation process according to an embodiment;

[0018] Figure 3 This is a diagram illustrating the structure of pixels according to an embodiment;

[0019] Figure 4 This is a diagram illustrating the configuration of the unevenness compensation device according to an embodiment;

[0020] Figure 5 This is a diagram illustrating the configuration of a data processing circuit according to an embodiment;

[0021] Figure 6 This is a flowchart illustrating a non-uniformity compensation method for a data processing circuit according to an embodiment;

[0022] Figure 7 This is a graph showing how the panel changes as the grayscale value varies within a non-uniform patch;

[0023] Figure 8 This is a diagram illustrating a first example of a method for calculating representative values ​​of uneven blocks according to an embodiment;

[0024] Figure 9 This is a diagram illustrating a second example of a method for calculating representative values ​​of uneven blocks according to an embodiment;

[0025] Figure 10 This is a diagram illustrating the traditional unevenness compensation method;

[0026] Figure 11 A diagram illustrating a non-uniformity compensation method according to an embodiment; and

[0027] Figure 12 This is a diagram illustrating variations in the memory based on global gain according to an embodiment. Detailed Implementation

[0028] Figure 1 This is a diagram illustrating the configuration of a display device according to an embodiment.

[0029] refer to Figure 1 The display device 100 may include a display panel 110, a data driving circuit 120 for driving the display panel 110, a pixel sensing circuit 130, a gate driving circuit 140, a data processing circuit 150, a host 160, etc.

[0030] In the display panel 110, multiple data lines (DL), gate lines (GL), and sensing lines (SL) can be arranged, and multiple pixels (P) can be arranged.

[0031] Depending on the circumstances, the display panel 110 may be configured to be removable from or integrated with the touch panel (not shown). Various types of panels, such as liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs), can be used as the display panel 110.

[0032] The data driving device 120 can supply data voltage to the pixel (P) via a data line (DL). The data voltage supplied to the data line (DL) can be transmitted to the pixel (P) connected to the data line (DL) according to the scan signal of the gate driving circuit 140. Depending on the situation, the data driving circuit 120 can be defined as a source driver.

[0033] The pixel sensing circuit 130 can receive analog signals (e.g., voltage, current, etc.) formed in each pixel (P) via a sensing line (SL), and can determine the characteristics of the pixel (P). Furthermore, the pixel sensing circuit 130 can sense the changes in the characteristics of each pixel (P) over time, and can transmit them to the data processing circuit 150.

[0034] The gate drive circuit 140 can supply a scan signal with an on or off voltage via a gate line (GL). If a scan signal with an on voltage is supplied to a pixel (P), the corresponding pixel (P) can be connected to the data line (DL). If a scan signal with an off voltage is supplied to a pixel (P), the corresponding pixel (P) is disconnected from the data line (DL). Depending on the situation, the gate drive circuit 140 can be defined as a gate driver.

[0035] The data processing circuit 150 can supply various control signals to the data driving circuit 120 and the gate driving circuit 140. The data processing circuit 150 can transmit a data control signal (DCS) or a gate control signal (GCS) to the gate driving circuit 140, wherein the data control signal (DCS) is used to control the data driving circuit 120 to correctly supply data voltage to each pixel (P) at various timings. Depending on the situation, the data processing circuit 150 can be defined as a timing controller (T-Con).

[0036] The data processing circuit 150 can output image data (RGB) to the data driving circuit 120 by converting externally input image data into a data signal format suitable for use in the data driving circuit 120.

[0037] The data processing circuit 150 can convert image data (RGB) in blocks defined based on the areas divided by the display panel 110. Furthermore, in order to compensate for differences in luminance or brightness associated with the grayscale values ​​of each block, a compensation value associated with the grayscale can be calculated, and the converted image data (RGB') can be generated.

[0038] The data processing circuit 150 can store at least one compensation value for each block and can perform compensation associated with the grayscale values ​​of each pixel in the block. Because at least one compensation value for each block is stored, the storage capacity of the compensation values ​​can be minimized. However, depending on the situation, compensation values ​​can be stored for each pixel.

[0039] The data processing circuit 150 can perform compensation associated with image data (RGB) based on the characteristics of the pixel (P) determined by the pixel sensing circuit 130, can transmit the compensation, and can receive sensing data from the pixel sensing circuit 130.

[0040] The data processing circuit 150 can control the brightness of each pixel arranged in the display panel 150 by using the converted image data (RGB').

[0041] The data processing circuit 150 can process digital signals to adjust the output of the analog signals from the data drive circuit 120. The data processing circuit 150 can calculate brightness values ​​or compensation values ​​for individual blocks on the panel to address unevenness. A block can be a region on the panel categorized by location. The data processing circuit 150 can obtain the final compensation value by calculating the brightness value or compensation value for each block in response to changes in grayscale values.

[0042] The host 160 can generate image data and transmit the image data to the data processing circuit 150. The host can be a central processing unit (CPU) and can include various types of processing devices such as microprocessors.

[0043] Figure 2 This is a diagram illustrating the signal flow of the non-uniformity compensation process according to an embodiment.

[0044] refer to Figure 2 In the unevenness compensation according to the embodiment, the camera device 10 can capture an image displayed on the display device 100, and the unevenness compensation device 20 can calculate a compensation value (DCp) for unevenness compensation and transmit the calculated compensation value to the display device 100 to compensate for the unevenness of the display panel 110. Depending on the situation, the unevenness compensation device 20 may be included in the display device 100.

[0045] The data processing circuit 150 can transmit image data (RGB) with a constant grayscale value to the data driving circuit 120. The data driving circuit 120, which receives the image data (RGB), can convert the image data (RGB) into a data voltage (Vd) and supply the data voltage (Vd) to the display panel 110. For example, the data voltage (Vd) can be a gamma voltage.

[0046] The display panel 110 can provide test images for each grayscale level for unevenness compensation. Signals with the same grayscale value can be supplied to the display panel 110, and a reference image can be displayed. A panel inspection device (not shown) determines the quality of the display panel or whether the display panel is operating normally based on a picture or image obtained by capturing the reference image.

[0047] The camera device 10 can capture test images of the display panel and can measure and store brightness values ​​for individual pixels or for individual blocks. Depending on the situation, the brightness values ​​can be stored in memory (not shown).

[0048] The unevenness compensation device 20 can receive a detection image obtained by capturing a test image displayed on the display panel 110, and can determine whether unevenness occurs in the display panel 110. Furthermore, the unevenness compensation device 20 can receive brightness values ​​(DLx) obtained from the camera device 10, calculate brightness values ​​for individual blocks or individual pixels, and calculate compensation values ​​to eliminate unevenness. Depending on the situation, the above processing can be repeated for predetermined grayscale values. For example, in addition to the brightness difference of the captured image, the unevenness characteristic can also be defined as the color difference of the captured image.

[0049] The unevenness compensation device 20 can determine whether unevenness occurs in the display panel 110 based on various reference values ​​such as the brightness, luminosity, lightness intensity, and color of the detected image.

[0050] The unevenness compensation device 20 can determine whether unevenness occurs based on image data of the entire panel. However, the required storage capacity increases rapidly. Therefore, by dividing the entire panel into (4×4) blocks to determine whether unevenness occurs for each block, the amount of memory used can be reduced. Depending on the situation, each block may include N×M pixels (N and M are natural numbers).

[0051] For example, the total number of blocks can be defined as (horizontal size) × (vertical size) × (number of subpixels) / (4×4 block size).

[0052] The brightness (Lx) or color of each pixel of the display panel 110, which receives a data voltage (Vd) corresponding to a grayscale value, can be controlled based on the data voltage (Vd). For example, the brightness difference (Lx) between pixels can be defined as unevenness.

[0053] The grayscale value can be selected from a range of 0 to 255. The brightness value (DLx) for each pixel or block can be calculated for each of the major grayscale values ​​(e.g., 32, 64, 128, 192, and 224), and the corresponding value can be stored in the unevenness compensation device 20.

[0054] The unevenness compensation device 20 can obtain multiple brightness values ​​(DLx) corresponding to multiple gray values, and can calculate compensation values ​​(DCp) corresponding to multiple gray values ​​to remove the unevenness caused by the difference between the target brightness value and the brightness value (DLx).

[0055] For example, the target brightness value can be determined primarily based on the brightness value of a block located at the center of the display panel. Depending on the situation, to reduce the amount of calculation associated with the brightness value of the block, a representative brightness value for the block can be defined, the brightness value of a specific pixel can be defined as the target brightness value, or the target brightness value can be determined by calculating the average of the brightness values ​​of multiple pixels.

[0056] The unevenness compensation device 20 can transmit the calculated compensation value (DCp) to an external device so that the compensation value (DCp) is stored in the memory 157 of the data processing circuit 150.

[0057] Figure 3 This is a diagram illustrating the structure of pixels according to an embodiment.

[0058] refer to Figure 3 The pixels (P) arranged in the display panel 110 may include organic light-emitting diodes (OLED), driving transistors (DRT), switching transistors (SWT), sensing transistors (SENT), storage capacitors (Cstg), etc.

[0059] The data driving circuit 120 can transmit a driving voltage (Vd) to each pixel (P) via a data line (DL), and the pixel sensing circuit 130 can receive the analog signals formed in each pixel (P) and determine the characteristics of the pixel (P). The data processing circuit 150 can analyze the pixel sensing data, identify the characteristics of each pixel (P), and control the driving signal.

[0060] Controlled by a driving transistor (DRT), the anode electrode is connected to the driving voltage (EVDD) and the cathode electrode is connected to the base voltage (EVSS), thus emitting light. The driving transistor (DRT) can control the driving current supplied to the OLED and can also control the brightness of the OLED.

[0061] According to an embodiment, the driving transistor (DRT) controls the driving current to change the brightness of the OLED, thereby compensating for unevenness.

[0062] The sensing transistor (SENT) can connect the first node (N1) of the driving transistor (DRT) and the sensing line (SL), and the sensing line (SL) can transmit a reference voltage (Vref) to the first node (N1) and can transmit an analog signal (e.g., voltage or current) formed in the first node (N1) to the pixel sensing circuit 130.

[0063] The pixel sensing circuit 130 can use analog signals (Vsense or Isense) transmitted via sensing lines (SL) to measure the characteristics of a pixel (P). The pixel sensing circuit 130 can measure the current transmitted from or to the first node (N1) and can transmit pixel sensing data (which is a digital signal associated with the measured value) to the data processing circuit 150.

[0064] The characteristics of the OLEDs and transistors included in each pixel (P) may vary over time or depending on the surrounding environment. Differences in brightness and color may occur in the display panel 110 due to manufacturing errors, variations in pixel (P) characteristics, external factors, etc., and this phenomenon can be defined as non-uniformity. Non-uniformity may occur when electrical and optical characteristics are not maintained equally in each pixel, and different criteria for determining non-uniformity can be set based on the non-uniformity characteristics.

[0065] The technical concept disclosed herein is not limited to the resolution of unevenness in OLED display panels, but can be applied to various types of display panels.

[0066] Figure 4 This is a diagram illustrating the configuration of the unevenness compensation device according to an embodiment.

[0067] refer to Figure 4 The unevenness compensation device 20 may include a receiving circuit 21, a calculation circuit 23, a transmission circuit 25, etc.

[0068] The receiving circuit 21 can obtain multiple brightness values ​​corresponding to multiple grayscale values ​​for each block of the display panel 110. The receiving circuit 21 can receive the brightness values ​​via communication with the camera device 10.

[0069] The receiving circuit 21 can obtain the brightness values ​​of the pixels in the block in order to calculate the representative compensation value defined for each block.

[0070] The computing circuit 23 can calculate a compensation value (DCp) for grayscale values ​​to resolve the unevenness caused by the difference between the target brightness value and the measured brightness value.

[0071] The computing circuit 23 can calculate compensation values ​​for grayscale values ​​to resolve unevenness caused by the difference between the target brightness value and the brightness value, and can generate representative compensation values ​​for each block. Here, a block can have representative compensation values ​​corresponding to grayscale values ​​or multiple representative compensation values ​​corresponding to different grayscale values. The technical idea of ​​this disclosure is to use representative compensation values ​​instead of compensation values ​​for all grayscale values ​​to reduce memory capacity requirements, and is not limited to the above example.

[0072] The computing circuit 23 can select one of a plurality of blocks on the display panel and can generate a global gain based on a plurality of brightness values ​​corresponding to a plurality of grayscale values.

[0073] The calculation circuit 23 can obtain the final compensation value by multiplying the representative compensation value for each block by the global gain. Depending on the circumstances, this can be processed by the data processing device 150.

[0074] The computational circuit 23 can generate an interpolation function based on multiple brightness values ​​corresponding to multiple grayscale values. The interpolation function can be a quadratic function or a higher-order function. However, this increases computational complexity and memory usage; therefore, the interpolation function can be configured as a linear function. Using an interpolation function allows for a reduction in the actual number of compensation values ​​obtained for each grayscale. Furthermore, a spectrum of compensation values ​​for various grayscale values ​​can be obtained as needed.

[0075] The computing circuit 23 can calculate a compensation value used to convert the measured brightness value into a grayscale value for compensation. For example, the data processing circuit can generate a grayscale value for compensation by applying the grayscale value to a linear function, and can calculate a gain value and an offset value applied to the linear function as compensation values.

[0076] The compensation value (DCp) can ultimately be inserted into the memory 157 of the data processing circuit 150 to drive the display panel. For this purpose, the transmission circuit 25 can transmit these compensation values ​​to means for storing the compensation values ​​in the memory 157 of the data processing circuit 150.

[0077] Depending on the circumstances, the unevenness compensation device 20 may be arranged inside the display device 100, or the unevenness compensation device 20 may be arranged separately from the display device 100 and may be configured as a separate device together with the camera device 10.

[0078] Figure 5 This is a diagram illustrating the configuration of a data processing circuit according to an embodiment.

[0079] refer to Figure 5 The data processing circuit 150 may include a receiving circuit 151, a compensation circuit 153, a transmission circuit 155, a memory 157, etc.

[0080] The receiving circuit 151 can receive image data. The receiving circuit 151 can receive image data via communication with the host 160 or the like.

[0081] The compensation circuit 153 can convert image data. The compensation circuit 153 can convert image data to compensate for pixel degradation and can also convert image data to add predetermined effects to the image. The compensation circuit 153 can convert image data in pixels or blocks to compensate for unevenness appearing in the panel.

[0082] If the grayscale value included in the image data corresponds to a predetermined grayscale value, the compensation circuit 153 can convert the corresponding grayscale value based on the compensation value. For other grayscale values ​​that are different from the predetermined grayscale value, the compensation circuit 153 can calculate the compensation value according to the interpolation scheme and can convert the corresponding grayscale value based on the calculated compensation value.

[0083] The compensation circuit 153 can identify the position of the pixel corresponding to the gray value included in the image data, select a block based on the corresponding position, identify the compensation value of the corresponding block from the memory 157, and perform compensation associated with the gray value.

[0084] When the converted image data is generated, the compensation circuit 153 can use a global gain defined based on multiple compensation values ​​corresponding to multiple grayscale values ​​for a block. Furthermore, the compensation circuit 153 can convert the image data based on a final compensation value obtained by multiplying the global gain by a representative compensation value for the block.

[0085] When calculating the final compensation value, the compensation circuit 153 can reuse a global gain, and the storage capacity of the memory 157 can be reduced when a global gain obtained in one block is applied to the calculation. In cases where the non-uniformity characteristics of the blocks are determined to be similar, the compensation circuit 153 can repeatedly use the same global gain for the calculation.

[0086] The converted image data can be obtained based on the calibrated grayscale values, and the transmission circuit 155 can transmit the converted image data to the data driving circuit.

[0087] Compensation values ​​used for converting image data can be stored in memory 157. Compensation values ​​used for unevenness compensation for individual blocks can be stored in memory 157. Memory 157 can store compensation values ​​for a predetermined grayscale value referred to as a "plane", or a set of compensation values ​​for multiple grayscale values.

[0088] Figure 6 This is a flowchart illustrating a non-uniformity compensation method 200 for a data processing circuit according to an embodiment.

[0089] The non-uniformity compensation method 200 of the data processing circuit or non-uniformity compensation device may include an operation S201 of calculating non-uniformity compensation values ​​for each block, an operation S203 of calculating representative non-uniformity compensation values ​​for each block, an operation S205 of calculating global gain, and an operation S207 of calculating final non-uniformity compensation values.

[0090] In operation S201, which calculates the unevenness compensation value for each block, test images for each grayscale are provided to the display panel for unevenness compensation, and the shape and size of the unevenness can be identified based on the brightness or color of the image data obtained by capturing the test images.

[0091] Furthermore, in the operation S201 of calculating the unevenness compensation value for each block, it is possible to determine whether unevenness has occurred by determining various unevenness factors such as brightness, luminance, and color of the image data for each uneven block including multiple pixels.

[0092] Here, uneven blocks can be defined as regions of the same size obtained by dividing the display panel. The size of the blocks can be uniformly increased, for example, by a factor of N (where N is a natural number), as needed.

[0093] In operation S203, which calculates the representative unevenness compensation value for each block, the region or pixels for which the unevenness compensation value is to be calculated can be defined for each block. The representative compensation value for each uneven block can be determined based on the data of the selected pixels or region.

[0094] In a normally operating display panel, if signals of the same grayscale are supplied, it is normal to obtain image data with the same characteristics (such as the same brightness, color, etc.).

[0095] If unevenness occurs, the characteristics of each pixel or region change. Therefore, unevenness compensation values ​​can be calculated for the uneven pixels or blocks, and compensation can be applied to calibrate the data of the uneven pixels or regions to have the same characteristics. Depending on the situation, unevenness compensation can be performed to bring the panel within the normal display range.

[0096] As a reference value for pixel-related compensation, the average pixel brightness value or the brightness value of the pixel located at the center of the panel can be used. The magnitude of the unevenness compensation value can be calculated to correspond to the magnitude of brightness values ​​that are larger or smaller than the reference value.

[0097] If compensation values ​​are calculated for each pixel of the display panel, the memory capacity may be insufficient. Therefore, it is necessary to determine whether unevenness occurs for each block and to generate compensation values ​​for unevenness for each block.

[0098] Furthermore, when the unevenness in each block has similar characteristics, instead of calculating the compensation value for all blocks, the compensation value for one block is calculated and used, which can improve the calculation speed and reduce memory usage.

[0099] In the operation S205 of calculating the global gain, a global gain can be calculated as a reference for compensation associated with the unevenness, so as to calibrate the representative compensation value of the unevenness based on the compensation reference value of the display panel. For example, the compensation reference value of the panel is defined as the average pixel brightness value, but it is not limited to this.

[0100] According to the embodiments, the same global gain can be applied to all blocks, and the final compensation value can be obtained by applying the same global gain to the corresponding representative compensation value of each uneven block.

[0101] According to the embodiment, if global gain is used, a single lookup table (LUT) is used based on a single block, which can reduce the amount of computation performed, which is advantageous.

[0102] Here, global gain can be the ratio or difference of the compensation value corresponding to the brightness value.

[0103] In operation S207, which calculates the final non-uniformity compensation value, the final compensation value can be obtained by multiplying the representative compensation value calculated in operation S203 with the global gain calculated in operation S205, and the non-uniformity of the non-uniform block can be removed.

[0104] Figure 7 This is a graph showing how the panel changes as the grayscale value changes within a non-uniform patch.

[0105] To calculate unevenness, a compensation value can be calculated for the entire area of ​​the display panel. However, to reduce the number of operations and memory usage, the compensation value can be calculated for each individual block.

[0106] In this case, if different gray values ​​are transmitted through the same block, different brightness values ​​or different compensation values ​​can be generated.

[0107] For example, when the grayscale values ​​of each pixel (A1, B1, C1, D1, E1, F1, G1, H1, I1, J1, K1, L1, M1, N1, O1, and P1) in block 1 are 32, 64, and 128 respectively in the corresponding cases, the brightness difference of the display panel in these cases can be calculated.

[0108] Figure 8 This is a diagram illustrating a first example of a method for calculating representative values ​​of uneven blocks according to an embodiment.

[0109] refer to Figure 8According to an embodiment, the representative value of the uneven block can be calculated by averaging the compensation values ​​of multiple pixels.

[0110] For example, the entire panel can be divided into blocks, each block having a 4×4 block size and comprising 16 pixels. Depending on the situation, each block can comprise N×M pixels (N and M are natural numbers). The block size is inversely proportional to the memory capacity. Therefore, if the block size increases, the memory capacity used decreases. The block size used as a reference can be adjusted as needed.

[0111] To calculate the representative value of a block, some pixels 401-1 of the block in the entire panel 410-1 are selected, and the representative compensation value of the block can be calculated. Depending on the situation, the representative compensation value of the block can be calculated by averaging the unevenness compensation values ​​of the selected pixels 401-1. In this case, when calculating the representative compensation value of a block for each block, compensation values ​​based on the same grayscale value can be used, but compensation values ​​based on different grayscale values ​​can also be used.

[0112] For example, for block 1, the representative value of the block can be calculated based on the compensation value at grayscale value 32. For block 2, the representative value of the block can be calculated based on the compensation value at grayscale value 64.

[0113] Figure 9 This is a diagram illustrating a second example of a method for calculating representative values ​​of uneven blocks according to an embodiment.

[0114] refer to Figure 9 According to an embodiment, the representative value of the uneven block can be calculated based on the compensation value for pixels 401-2 arranged at predetermined positions.

[0115] In this case, the compensation value for the unselected pixel 402-2 does not need to be calculated, thus reducing the number of processor operations and the amount of memory used.

[0116] For example, you can select pixels located in J1 in block 1, and you can select pixels located in J2 in block 2. However, the selected positions can be defined differently depending on the situation.

[0117] The compensation value is determined to be a single representative value for each block. In this case, the number of variables used is reduced, and therefore the required memory capacity can be reduced. Depending on the situation, the compensation value for each block can be easily calculated by defining it as a single matrix.

[0118] The unevenness compensation value can be on the order of 8 bits, ranging from -128 to 127. Depending on the situation, the compensation value can be on the order of 10 bits, ranging from -512 to 511, and on the order of 12 bits, ranging from -2048 to 2047. The required memory level can be adjusted based on the desired precision.

[0119] Figure 10 This is a diagram illustrating the traditional unevenness compensation method.

[0120] refer to Figure 10 The curve 500 shows the distribution of the non-uniformity compensation values ​​for each gray level.

[0121] In the case of compensation values ​​for each grayscale, if the grayscale value is set in the range of 0 to 255, the change in the compensation value of block 1 can be calculated by performing a total of 256 operations in block 1.

[0122] If compensation values ​​are calculated for all grayscale values, the number of operations required can increase rapidly. According to conventional non-uniformity compensation methods, such as those disclosed in Korean Patent Application KR 10-2020-0079920 A, non-uniformity compensation values ​​can be calculated by plotting based on five measurements. In conventional methods, the coefficients of the quadratic function used for each block are stored in memory; therefore, memory usage can increase proportionally to the number of coefficients in the quadratic function.

[0123] In other words, if a quadratic function is used for unevenness compensation, it may require a memory size of (horizontal size) × (vertical size) × (number of subpixels) / (4 × 4 block size) × (24 bits) to store the coefficients a of the quadratic term, b of the linear term, and c of the constant term.

[0124] Furthermore, if a quadratic function is used to calculate the unevenness compensation value according to the traditional unevenness compensation method, the accuracy of the calculation may vary for each block. For example, in the case of block 4, whose characteristics differ from those of its adjacent blocks, the distribution of the unevenness compensation value for block 4 may differ from the distribution of the compensation values ​​for blocks 1 to 3. Calculation errors can be used as a factor that reduces the accuracy of unevenness compensation. When the unevenness of the display panel is more severe, the accuracy of calculating the unevenness compensation value using a quadratic function may decrease.

[0125] Figure 11 This is a diagram illustrating the non-uniformity compensation method according to an embodiment.

[0126] refer to Figure 11 The curve 600 shows the distribution of the unevenness compensation values ​​for each grayscale value.

[0127] Traditionally, non-uniformity compensation is performed by configuring three to five lookup tables (LUTs). However, the data processing circuit 150 according to the embodiment can generate a single lookup table (LUT) for non-uniformity compensation.

[0128] According to the embodiment, the data processing circuit 150 can provide a method for calculating unevenness compensation value, which improves the accuracy of unevenness compensation and reduces the amount of memory used by using global gain as a global variable.

[0129] Here, the global gain can be a set of compensation values ​​or compensation ratios stored in a lookup table.

[0130] The unevenness compensation device 20 can select a single block and calculate compensation values ​​for each gray level of the block to generate a global gain. For example, the global gain can be calculated by selecting block 1. However, the global gain can be obtained based on other blocks.

[0131] If the non-uniformity characteristics are identified as similar and the non-uniformity intensities are different in each block by recognizing the non-uniformity characteristics of all gray levels, then global gain can be used and the amount of memory used can be reduced.

[0132] If the blocks have similar properties, the lookup table (LUT) obtained based on a single block can be applied equally to the calculation of unevenness compensation values ​​for each block.

[0133] In a different block than the one used to obtain the lookup table (LUT), a single unevenness compensation value is calculated for each grayscale value. A global gain can be applied based on these unevenness compensation values, and the required unevenness compensation values ​​for all grayscale values ​​can be calculated.

[0134] For example, a single lookup table (LUT) can be configured as follows: calculate the unevenness compensation value D21 at grayscale value 32 in block 1, calculate the unevenness compensation value D22 at grayscale value 64 in block 1, calculate the unevenness compensation value D23 at grayscale value 128 in block 1, calculate the unevenness compensation value D24 at grayscale value 192 in block 1, and calculate the unevenness compensation value D25 at grayscale value 224 in block 1. Depending on the circumstances, the unevenness compensation value D25 at grayscale value 224 can be defined as the representative compensation value of block 1, but this is not a limitation.

[0135] Subsequently, if the same operation is repeated in blocks 2 through 4, the number of operations performed can increase proportionally to the number of blocks. However, if the global gain according to the embodiment is used, the number of operations performed by the data processing device and the amount of memory used can be reduced by using only a single lookup table (LUT).

[0136] To apply the global gain, the ratio of the unevenness compensation value can be calculated for each block. For example, if the unevenness compensation value at grayscale value 32 in block 1 is 10 and the unevenness compensation value at grayscale value 32 in block 2 is 5, then the ratio of the unevenness compensation value is defined as 0.5.

[0137] Furthermore, unlike calculating unevenness compensation values ​​at all grayscale values, the unevenness compensation method of the data processing apparatus according to the embodiment can calculate unevenness compensation values ​​representing some grayscale values, and can interpolate them to reduce the number of operations performed and the amount of memory used. For example, when the compensation value changes with the grayscale value, the number of variables used can be reduced by linear interpolation.

[0138] According to another embodiment, a lookup table (LUT) can be configured by obtaining a global gain based on a single block using the quadratic function plotting method described above. In this case, the quadratic function plotting method is not applied to other blocks, and the obtained global gain is applied, which can reduce the number of variables used.

[0139] Considering the intervals of grayscale values ​​and compensation values, the error in the interpolation part is irrelevant; therefore, the obtained unevenness compensation value can be used without additional data processing.

[0140] By using the global gain according to the embodiment, errors in block-based operations associated with blocks having similar non-uniform characteristics (such as block 4) can be reduced. Using the global gain can prevent... Figure 8 The above-mentioned plotting errors.

[0141] If the global gain based on a single lookup table (LUT) according to the embodiment is used, a single plane is required, and therefore, a memory size of (horizontal size) × (vertical size) × (number of subpixels) / (4 × 4 block size) × (8 bits) may be required.

[0142] Depending on the circumstances, each block comprises N×M pixels (N and M are natural numbers), and the required memory size can be 8 to 12 bits, depending on the precision of the compensation values. Uneven blocks can be defined as having at least two regions of the same size obtained by dividing the display panel, but are not limited to this.

[0143] Compared to traditional memory sizes that require multiple planes, the required memory size can be reduced proportionally to the reduction in the number of planes.

[0144] The unevenness compensation device can define a global gain differently for each sub-pixel, and can define a global gain for sub-pixel R, a global gain for sub-pixel GL, a global gain for sub-pixel GR, and a global gain for sub-pixel B.

[0145] The grayscale values ​​required to calculate the compensation value can be defined as "planes". In this case, the number of registers for the global gain can be obtained based on (number of planes) × (number of subpixels).

[0146] For example, with 5 planes and 4 sub-pixels, the total number of registers for global gain can be 5 × 4 = 20.

[0147] The final non-uniformity compensation value can be obtained by multiplying the representative compensation value for each block calculated in the non-uniformity compensation device 20 with the global gain.

[0148] The unevenness compensation device 20 can obtain representative compensation values ​​for each block at the same grayscale value, and can also obtain representative compensation values ​​for each block at different grayscale values. The individual values ​​obtained according to the above-described representative compensation value calculation method can be stored in the memory 157.

[0149] Depending on the circumstances, the unevenness compensation device 20 can compare the unevenness compensation values ​​obtained at different grayscale values.

[0150] The unevenness compensation device according to the embodiment can store only a single representative compensation value for each block, and can reduce the amount of memory 157 used. Furthermore, the unevenness compensation device can generate a single lookup table (LUT) as a single global gain, and can further reduce the amount of memory 157 used. Here, a lookup table means a plane, and can be physically or logically divided into multiple parts.

[0151] The circuit described above may be included in the unevenness compensation device 20, or may be included separately in the display device 100 or the data processing circuit 150.

[0152] Figure 12 This is a diagram illustrating variations in the memory based on global gain according to an embodiment.

[0153] refer to Figure 12 There is a comparison between the memory usage capacity 700A according to the conventional non-uniformity compensation method and the memory usage capacity 700B according to the non-uniformity compensation method based on the embodiment.

[0154] According to the conventional non-uniformity compensation method disclosed in Korean Patent Application 10-2020-0079920A, it is necessary to store all the coefficients of the quadratic function. For example, if a quadratic function is used for non-uniformity compensation, the memory capacity may consume 8 bits of memory for each parameter to store the coefficient 'a' of the quadratic term, the coefficient 'b' of the linear term, and the coefficient 'c' of the constant term, and the entire memory 700A may consume 24 bits.

[0155] Unlike the above, the memory capacity required for operation using a single lookup table (LUT) according to the embodiment can be 8 bits, which is one-third of the memory capacity required by conventional methods. Therefore, memory is used more efficiently. For example, 8 bits of memory capacity can be consumed to store the global gain calculated based on a single block, and another block needs a single brightness value corresponding to a single grayscale value; therefore, no additional memory capacity is required.

[0156] The terms “compensation value” and “brightness compensation value” used in this specification may be defined differently depending on the measurement method of the panel, and may mean compensation value used for unevenness compensation.

[0157] The term "block" as used in this specification can be defined as a group of at least one pixel, and its shape or size is not limited. A block can be defined as a region or a group of pixels as needed.

[0158] The term "lookup table" used in this specification can refer to a data set and can be defined in various ways. For example, the number of lookup tables can be determined based on the size of the lookup table for the data set. A lookup table can be considered as a plane and can be physically and logically divided into multiple parts.

[0159] Cross-references to related applications

[0160] This application claims priority to Korean Patent Application No. 10-2020-0166598, filed on December 2, 2020, which is incorporated herein by reference for all purposes, as fully set forth herein.

Claims

1. A data processing circuit, comprising: A receiving circuit is configured to receive image data including grayscale values ​​associated with pixels arranged in a display panel. The memory stores representative compensation values ​​associated with grayscale values ​​of various regions of the display panel, wherein the representative compensation values ​​are compensation values ​​for specific pixels in a region of the display panel or the average of compensation values ​​for multiple pixels. The compensation circuit is configured to calculate a final compensation value by multiplying the representative compensation value of each region by a global gain, the global gain being a gain factor defined based on multiple compensation values ​​corresponding to multiple grayscale values ​​associated with a single region of the display panel, and to generate converted image data. as well as A transmission circuit is configured to transmit the converted image data to a data driving circuit.

2. The data processing circuit according to claim 1, wherein, The global gain is obtained via a single lookup table, and the global gain includes a compensation value obtained by linear interpolation of a compensation value for a predetermined grayscale value.

3. The data processing circuit according to claim 1, wherein, The memory stores the global gain and the final compensation value calculated by the compensation circuit.

4. The data processing circuit according to claim 1, wherein, The compensation circuit selects regions based on the position of each pixel, determines whether unevenness occurs in each region, and generates converted image data.

5. The data processing circuit according to claim 1, wherein, The compensation circuit repeatedly applies the same global gain to the final compensation value for each region.

6. The data processing circuit according to claim 1, wherein, The representative compensation value for the grayscale value of a region is calculated based on the difference between the brightness value of a pixel in each region and the target brightness value.

7. A non-uniformity compensation device, comprising: The receiving circuit is configured to obtain multiple brightness values ​​corresponding to multiple grayscale values ​​associated with a single area of ​​the display panel; as well as A computing circuit is configured to calculate a compensation value for the grayscale value to resolve unevenness caused by the difference between the brightness value and the target brightness value, and to calculate a final compensation value by generating representative compensation values ​​for each region. The representative compensation value is either a compensation value for a specific pixel in a region of the display panel, or an average of compensation values ​​for multiple pixels. The computing circuit is further configured to generate a global gain based on multiple brightness values ​​corresponding to multiple grayscale values ​​associated with a single area of ​​the display panel. This global gain is obtained from a lookup table or interpolation function and is applied as a gain factor to the multiple areas. The calculation circuit is further configured to calculate the final compensation value by multiplying the representative compensation value of each region by the global gain, wherein the global gain is applied to each region of the display panel. The computing circuit is further configured to calculate the final compensation value by applying the global gain to the representative compensation value.

8. The unevenness compensation device according to claim 7, wherein, In order to calculate the representative compensation value defined for each region, the receiving circuit obtains the brightness value of one or more pixels in the region.

9. The unevenness compensation device according to claim 7, wherein, The computational circuit generates an interpolation function based on multiple brightness values ​​corresponding to multiple grayscale values.

10. The unevenness compensation device according to claim 9, wherein, The interpolation function includes a linear function, and the computational circuit uses the interpolation function to obtain the global gain.

11. The unevenness compensation device according to claim 7, wherein, The calculation circuit stores the ratio of the compensation value corresponding to the brightness value in a lookup table (LUT) and uses the lookup table to obtain the final compensation value.

12. A non-uniformity compensation method, comprising: Calculate the brightness compensation value for multiple pixels in uneven regions of image data; The brightness compensation values ​​for the plurality of pixels are used to calculate a representative compensation value for each uneven region, which is either a compensation value for a specific pixel in a region of the display panel or an average of the compensation values ​​for the plurality of pixels. The global gain for a predetermined grayscale value is calculated based on a single uneven region. The global gain is a gain factor defined based on multiple compensation values ​​corresponding to multiple grayscale values ​​associated with the single uneven region. as well as The final non-uniformity compensation value is obtained by multiplying the representative compensation value for each non-uniform region by the global gain.

13. The unevenness compensation method according to claim 12, wherein, The image data is obtained by displaying a reference image with the same grayscale on the display panel and capturing the reference image.

14. The unevenness compensation method according to claim 12, wherein, The representative compensation value for each uneven region is obtained by using the brightness data stored in memory for each region.

15. The unevenness compensation method according to claim 12, wherein, The global gain for a predetermined grayscale value in an uneven region is obtained via a single lookup table.

16. The unevenness compensation method according to claim 12, wherein, The uneven area is obtained by dividing the display panel into at least two areas of the same size, and the brightness compensation value is a brightness compensation value for each gray value in the uneven area.

Images