KR101953262B1 - Apparatus and Method for Generating of Luminance Correction Data - Google Patents

Abstract

The present invention relates to an apparatus and method for generating luminance correction data capable of preventing image quality distortion such as spot defects.
According to an embodiment of the present invention, an apparatus for generating luminance correction data includes: an intermediate value calculator configured to receive an luminance correction value of a first point and a second point and calculate an intermediate value; A reference value calculator for checking whether the intermediate value input from the intermediate value calculator is a final value and outputting the intermediate value as a final value or calculating a new reference value; And an output unit for outputting a final value from the reference value calculator as luminance correction data of a third point located between the first point and the second point.

Description

Apparatus and Method for Generating of Luminance Correction Data

The present invention relates to an apparatus and method for generating luminance correction data capable of preventing image quality distortion such as spot defects.

The flat panel display includes a liquid crystal display device (LCD), a field emission display device (FED), a plasma display panel (PDP), and an organic light emitting diode display (OLED). emitting diode display device) has been developed.

Among the flat panel display devices, the organic light emitting diode display device of the self-emission type is attracting attention as a next generation display device because of its advantages of high speed response speed, low power consumption, high resolution, and large screen.

1 is a circuit diagram schematically illustrating a pixel structure of an organic light emitting diode display according to the related art.

Referring to FIG. 1, a pixel of a conventional organic light emitting diode display includes a switching thin film transistor ST, a driving thin film transistor DT, a capacitor C, and a light emitting device OLED.

The switching thin film transistor ST is switched according to a scan signal supplied to the scan line SL to supply a data voltage Vdata supplied to the data line DL to the driving thin film transistor DT.

The driving thin film transistor DT is switched according to the data voltage Vdata supplied from the switching thin film transistor ST to control the data current idata flowing from the driving power supply Vdd to the light emitting device OLED.

The capacitor C is connected between the gate terminal of the driving thin film transistor DT and the ground line VL to store a voltage corresponding to the data voltage Vdata supplied to the gate terminal of the driving thin film transistor DT, and stores the stored voltage. As a result, the turn-on state of the driving thin film transistor DT is kept constant for one frame.

The light emitting device OLED is electrically connected between the source terminal of the driving thin film transistor DT and the ground power supply Vss to emit light by the data current idata supplied from the driving thin film transistor DT. In this case, the data current idata flowing in the light emitting device OLED may include the voltage Vgs between the gate and the source of the driving thin film transistor DT, the threshold voltage Vth of the driving thin film transistor DT, and the data voltage Vdata. Is determined by).

The pixel of the conventional organic light emitting diode display includes a data current idata flowing from the driving power supply Vdd to the light emitting device OLED by switching the driving thin film transistor DT according to the data voltage Vdata. By controlling the size, the light emitting device OLED emits light, thereby displaying a predetermined image.

In general, when the same manufacturing process is applied, all the OLED panels produced should have the same brightness characteristics, but in actual manufacturing process, there is a deviation so that all the OLED panels do not show the same brightness characteristics. In addition, deviations may occur between the initially designed luminance characteristics and the luminance characteristics after the manufacture is completed. Such variation in luminance characteristics may be different for each OLED panel and may be different for each pixel in one OLED panel.

As a result, even when the same data voltage Vdata is supplied to all the pixels, a difference is generated in the threshold voltage deviation and channel mobility of the driving thin film transistor DT included in each pixel. Accordingly, there is a problem in that luminance deviation occurs and image quality distortion phenomenon such as mura occurs.

2 and 3 are views illustrating a luminance correction method of an organic light emitting display device according to the prior art.

2 and 3, after the manufacture of the OLED panel is completed, the screen inspection of the OLED panel is performed before the product is released to the product to correct spot defects for all pixels. At this time, in order to reduce the amount of calculation for calculating the luminance correction data, as shown in FIG. 2, the luminance correction data Q (X1) at the first point X1 and the luminance correction data at the second point X2. The interpolation method is applied to (Q (X2)) to generate luminance correction data Q (X) of the target point X3.

As shown in FIG. 3, gray interpolation and block interpolation are generally used for Mura compensation of the entire screen.

First, the gray interpolation method is different from the correction data according to gray, so that luminance compensation data is generated for the reference luminance (for example, 32, 64, 128, 255 gray), and then the rest is performed. Gray luminance compensation data is generated by applying an interpolation method using reference luminance.

Second, block interpolation is a method of reducing hardware burden. Instead of calculating compensation data for all pixels, all pixels are divided into m × n pixel units such as 4 × 4 pixel units or 8 × 8 pixel units. It divides into blocks and produces | generates the luminance correction data represented by each block. Thereafter, interpolation is applied to representative luminance correction data of each block to generate and apply luminance correction data of pixels included in the block.

The gray interpolation method and the block interpolation method according to the related art described above may basically be implemented by hardware logic that calculates an expression including multiplication. Since high speed / high resolution models using multiple image data ports are more likely to be used, gray interpolation must be applied to the red (R), green (G), blue (B), white (W) subpixels, and every port. A number multiplier is required, which increases the hardware logic of the luminance compensation data generating device.

Gray interpolation requires two multipliers for four ports and four reference grays (32, 64, 128, and 255 grays) if one pixel consists of four color sub-pixels of RGBW. 4RGBW x 4port x 4gray x 2 Multiplier = 128ea Multiplier).

In the block interpolation method, when one pixel is composed of four color subpixels of RGBW, eight multipliers are required for each of four ports, and thus, a total of 128 multipliers (4 RGBW × 4port × 8Multiplier = 128ea Multiplier) are required.

Accordingly, there is another problem that the memory is increased and the manufacturing cost is increased. In addition, it takes a long time to generate and load the luminance correction data, which makes it difficult to apply to high speed / high resolution products. Accordingly, there is a need for a new apparatus and method capable of improving or preventing image quality distortion caused by uneven luminance of each pixel of a display device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide an apparatus and method for generating luminance correction data capable of reducing hardware logic for generating luminance correction data.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an apparatus and method for generating luminance correction data capable of preventing image quality distortion such as spot defects.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is a technical object of the present invention to provide a luminance correction method of an organic light emitting display device.

In addition to the technical task of the present invention mentioned above, other features and advantages of the present invention will be described below, or from such description and description will be clearly understood by those skilled in the art.

According to an aspect of the present invention, there is provided an apparatus for generating luminance correction data, the apparatus including: an intermediate value calculator configured to calculate an intermediate value by receiving luminance correction values of first and second points; A reference value calculator for checking whether the intermediate value input from the intermediate value calculator is a final value and outputting the intermediate value as a final value or calculating a new reference value; And an output unit for outputting a final value from the reference value calculator as luminance correction data of a third point located between the first point and the second point.

According to an aspect of the present invention, there is provided a method of generating luminance correction data, the method comprising: calculating an intermediate value by receiving luminance correction values of a first point and a second point; Checking whether the input intermediate value is a final value, outputting the input intermediate value as a final value or calculating a new reference value according to a result of checking the final value; And if the final value is satisfied, outputting the final value as luminance correction data of a third point located between the first point and the second point.

According to the above solution, the apparatus and method for generating luminance correction data according to an embodiment of the present invention can reduce hardware logic for generating luminance correction data.

According to the solving means of the above, the apparatus and method for generating luminance correction data according to an embodiment of the present invention can improve or prevent image quality distortion caused by luminance unevenness of pixels.

In addition to the features and effects of the present invention mentioned above, other features and effects of the present invention may be newly understood through the embodiments of the present invention.

1 is a circuit diagram schematically illustrating a pixel structure of an organic light emitting diode display according to the related art.
2 and 3 are views illustrating a luminance correction method of an organic light emitting display device according to the prior art.
4 is a diagram illustrating an apparatus for generating luminance correction data according to an embodiment of the present invention.
5 and 6 illustrate a method of generating luminance correction data according to an exemplary embodiment of the present invention.
7 is a diagram illustrating an organic light emitting display device to which luminance correction data is applied according to an exemplary embodiment of the present invention.

Hereinafter, a luminance correction method of an organic light emitting display device according to the present invention and a preferred embodiment of the luminance correction data generating device and method will be described in detail with reference to the accompanying drawings.

4 is a diagram illustrating an apparatus for generating luminance correction data according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the apparatus 100 for generating luminance correction data according to an exemplary embodiment of the present invention includes an intermediate value calculator 110, a reference value calculator 120, and an outputter 130.

Although not shown in the drawing, the test image is supplied to the OLED panel using the test image supply unit, and the luminance of the image displayed on the OLED panel is measured using the luminance measuring device. The luminance measuring device may be a digital camera or an image sensor.

The luminance correction data generating apparatus 100 according to an exemplary embodiment may implement an interpolation method using an adder and a bit shift operation using the luminance value measured by the luminance measuring device as an input value.

The test image supply unit (not shown) generates first to fourth test images having different gray scale values, and supplies data of the generated first to fourth test images to the organic light emitting display device. For example, the first test image may be displayed in 32 gray levels, the second test image in 64 gray levels, the third test image in 128 gray levels, and the fourth test image in gray levels.

In this case, the test image supply unit may sequentially supply the first to fourth test images to the organic light emitting display device, or may supply one test image of the first to fourth test images to the organic light emitting display device.

The OLED panel displays a test image supplied from the test image supply unit, and the luminance measuring device measures the luminance of the test image displayed on the OLED panel. In this case, the OLED panel may sequentially display the first to fourth test images, or may display one test image.

The luminance measuring apparatus provides the luminance detection unit 210 with image data of the test image obtained by capturing the test image displayed by being positioned in front of the OLED panel. In this case, when the first to fourth test images are displayed on the OLED panel, the first to fourth image pickup data corresponding to the first to fourth test images are generated, that is, the reference luminance value for luminance correction is generated to generate the luminance correction data generating apparatus 100. To provide.

Meanwhile, when only one test image is displayed among the first to fourth test images on the OLED panel, one imaging data corresponding thereto is generated, that is, a reference luminance value for luminance correction is generated to generate a luminance correction data generating apparatus. Provided at 100.

5 and 6 illustrate a method of generating luminance correction data according to an exemplary embodiment of the present invention. Hereinafter, an apparatus and method for generating luminance correction data according to an exemplary embodiment of the present invention will be described with reference to FIGS. 5 and 6.

The luminance measuring apparatus provides a reference luminance value to the intermediate value calculator 110 of the luminance correction data generating apparatus 100. In this case, instead of generating reference luminance values for all pixels, reference luminance values may be generated in a predetermined number of pixels and provided to the intermediate value calculator 110.

The median value calculator 110 calculates a median value for the input A and B reference values as a Median filter (S10). Specifically, the intermediate value calculation unit 110 calculates the luminance correction value A at the X1 point and the luminance correction value B at the X2 point, as shown in the following equation Q (X3) = (X1 + X2) / 2. After that, by dividing by 2, the X3 point located between the X1 point and the X2 point is detected, and the luminance correction value of the X3 point is calculated. At this time, the luminance correction value at the X3 point is output as the first intermediate value. The first intermediate value of the X3 point calculated by the intermediate value calculator 110 is provided to the reference value calculator 120.

The reference value calculator 120 checks whether the output value of the intermediate value calculator 110 reaches a final value (S20).

As a result of checking in S20, when the output value reaches the final value, the last calculated luminance value is provided to the output unit 130 as the final value.

On the other hand, as a result of confirming in S20, the reference value calculator 120, if the output value (for example, the first intermediate value) of the intermediate value calculation unit 110 does not reach the final value, the new reference value (a, b) is calculated and provided to the intermediate value calculating unit 110 (S30).

The intermediate value calculating unit 110 uses the first intermediate value of the X3 point and the luminance correction value of the X2 point provided from the reference value calculating unit 120 to generate a new intermediate value (for example, the second intermediate value) (a, calculate b).

Specifically, the intermediate value calculating unit 110 adds the first intermediate value of the point X3 and the luminance correction value B of the point X2, as shown in the following equation Q (X4) = (X3 + X2) / 2. By dividing by 2, the X4 point is detected, and the luminance correction value (for example, the second intermediate value) of the X4 point is calculated. Therefore, the intermediate value calculator 110 provides the calculated luminance correction value (eg, the second intermediate value) at the X4 point to the reference value output unit 120.

Subsequently, when the second intermediate value calculated in the previous step does not reach the final value, the reference value calculator 120 calculates the first intermediate value of the X3 point and the second intermediate value of the X4 point as a new reference value. The intermediate value calculator 110 is provided.

If the first intermediate value of the X3 point and the second intermediate value of the X4 point are input as new values from the reference value calculator 120, the intermediate value calculator 110 repeats the operation of S10. At this time, as shown in the following equation Q (X) = (X4 + X3) / 2, the first intermediate value of the X3 point and the second intermediate value of the X4 point are added, and then divided by 2 to obtain the luminance correction value of the X point ( QX) is calculated. Thereafter, the calculated luminance correction value QX at the X point is provided to the reference value calculator 120.

 The reference value calculator 120 performs the step S20 again to check whether the luminance value QX of the X point output from the intermediate value calculator 110 reaches a final value.

As a result of the check, when the output value does not reach the final value, the reference value calculator 120 performs the step S30 again to calculate a new intermediate value, and then the intermediate value calculator 110 and the reference value calculator 120 repeats the above-described step S10, S20.

On the other hand, when the output value reaches the final value as a result of the check, the reference value calculator 120 provides the output value 130 to the output value 130 as the final value, that is, the luminance value QX of the last point, that is, the X point do.

Thereafter, the output unit 130 generates and outputs the input final value QX as luminance correction data at the X point.

Luminance correction data for luminance correction of a plurality of points generated and output by the output unit 130 may be stored in a memory of the display apparatus, so that luminance correction may be performed on pixels in which luminance distortion is generated.

Here, N and outputting the value to reach the final value is the number of times of calculating the maximum number of times that is, intermediate values to go through the calculation unit (110) Median filter the median satisfy the following equation: X2-X1 = 2 ^N Should be In addition, since the latency required to calculate the final output value is very important for pipelined operation without interruption of the operation flow, the number of times to filter the final output value of S20 is expressed by Equation X2-X1. It should be equal to N satisfying = 2 ^N.

On the other hand, if the final value is calculated before the number of passes of the Median filter for pipelined (N), the delay filter for matching the latency of the final output may be further included. have.

In the present invention, the number of filtering passes through the intermediate value calculation unit 110 and the reference value calculation unit 120 is ^{N such} that X2-X1 = ^2N is always satisfied. This enables interpolation with simple hardware logic that uses only adders and shift operations, thereby reducing hardware logic and thus reducing the manufacturing cost of an ASIC chip or FPGA.

The generation of luminance correction data for an arbitrary point may be generated for four representative gray levels, that is, 32 gray levels, 64 gray levels, 128 gray levels, and 256 gray levels, among all grays.

In addition, generation of luminance correction data for an arbitrary point may be performed by dividing the entire screen, that is, all pixels into a plurality of blocks, and for each block. In this case, each block may be configured in units of 4 × 4 pixels or 8 × 8 pixels.

That is, after calculating the luminance correction values of the X1 and X2 points in two adjacent blocks, as described above, the addition operation and the shift operation using the luminance correction values of the X1 and X2 points are repeatedly performed to perform the luminance of the final target pixel. The correction value can be calculated.

As the size of the block increases, the size of the luminance correction data can be reduced, but the error of the luminance correction data increases in proportion to the size of the block. Therefore, in the present invention, the size of the block is set in units of 4x4 pixels or 8x8 pixels as the magnitude of the negligible error.

The luminance correction data generated by the above-described luminance correction data generating device corrects the luminance so that a gray level according to the input image data is displayed on the pixel. The luminance is corrected by subtracting the gradation of the input image data. On the contrary, when a luminance deviation that lowers the actual luminance from the input image data is generated, the luminance is corrected by adding the gray level of the image data input to the pixel.

7 is a diagram illustrating an organic light emitting display device to which luminance correction data is applied according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the organic light emitting display device 200 includes an OLED panel 210 and a panel driver. The panel driver includes a gate driver 220, a data driver 230, a timing controller 240, and a memory 250. The panel driver generates a data signal corresponding to input data input from the outside and supplies the same to each pixel.

The OLED panel 210 emits an organic light emitting diode OLED formed in each sub pixel according to a data voltage Vdata supplied from the data driver 230 to display an image. To this end, the OLED panel 210 is formed to cross each other and a plurality of first data lines DL, a plurality of scan lines SL, and a plurality of first lines formed side by side in a plurality of data lines DL to define a pixel area. And a plurality of second power lines PL2 formed to intersect the power line PL1 and the plurality of first power lines PL1.

The plurality of data lines DL are formed at regular intervals along the first direction, and the plurality of scan lines SL are formed at regular intervals along the second direction crossing the first direction. The first power line PL1 is formed to be adjacent to each of the plurality of data lines DL so as to receive the first driving power from the outside.

Each of the plurality of second power lines PL2 is formed to cross the plurality of first power lines PL1 to receive a second driving power source from the outside. In this case, the second driving power source may have a lower potential voltage level lower than that of the first driving power source or may have a ground (or ground) voltage level.

Meanwhile, the OLED panel 210 may include a common electrode instead of the plurality of second power lines PL2. In this case, the common electrode may be formed in the entire display area of the OLED panel 210 to receive the second driving power from the outside.

As an example, the sub-pixel may be divided into a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the red sub-pixel, the green sub-pixel, and the blue sub-pixels constitute one pixel.

As another example, a sub pixel may be divided into a red sub pixel, a green sub pixel, a blue sub pixel, and a white sub pixel, and the red sub pixel, the green sub pixel, the blue sub pixel, and the white sub pixels may be divided into one. It constitutes a pixel.

The organic light emitting diode OLED is formed between an anode electrode (or a pixel electrode) connected to the pixel circuit, a cathode electrode (or a reflective electrode) connected to the second driving power supply line PL2, and between the anode electrode and the cathode electrode and is red. And an organic light emitting cell emitting light of any one of green, blue, and white colors.

Here, the organic light emitting cell may be formed to have a structure of a hole transport layer / organic light emitting layer / electron transport layer or a structure of a hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer. In addition, the organic light emitting cell may be further formed with a functional layer for improving the luminous efficiency and / or lifespan of the organic light emitting layer.

The pixel circuit corresponds to the data signal Vdata supplied from the data driver 230 to the data line DL in response to the scan signal SS supplied from the gate driver 220 to the scan line SL. Flows through the organic light emitting element OLED.

To this end, the pixel circuit PC includes a switching transistor, a driving transistor, and at least one capacitor formed on a substrate by a thin film transistor forming process.

The switching transistor is switched according to the scan signal SS supplied to the scan line SL to supply a data voltage Vdata supplied from the data line DL to the driving transistor.

The driving transistor is switched according to the data voltage Vdata supplied from the switching transistor to generate a data current based on the data voltage Vdata and to supply the OLED to the organic light emitting diode OLED so that the driving transistor is proportional to the amount of data current. Emits light. The at least one capacitor maintains the data voltage supplied to the driving transistor for one frame.

The timing controller 240 controls driving timing of each of the gate driver 220 and the data driver 230 according to a timing synchronization signal sync input from an external system main body (not shown) or a graphics card (not shown). do.

The timing controller 240 generates a scan control signal and a data control signal based on timing synchronization signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable DE, a clock DCLK, and the like. The driving timing of the gate driver 220 is controlled through the scan control signal. Then, the driving timing of the data driver 230 is controlled through the data control signal DCS.

The memory 250 is configured to be included in the organic light emitting display device, and the memory 250 stores luminance correction data to prevent image quality distortion such as spot defects due to luminance unevenness of all pixels of the OLED panel.

The timing controller 240 loads the luminance correction data stored in the memory 250 and corrects the luminance of all pixels by reflecting the luminance correction data in the image data supplied to the OLED panel 210. At this time, the timing controller 240 aligns the red, green, blue, and white data to be suitable for driving the OLED panel, and supplies the aligned data RGBW to the data driver 230. The memory 250 in which the luminance correction data is stored may be implemented in a form embedded in the timing controller 240.

Meanwhile, although the above-described luminance correction data generating apparatus and the luminance correction data generating method using the same are described as correcting the luminance of the pixels of the OLED panel, the present invention is not limited thereto, and each sub pixel may be formed of a liquid crystal cell or a discharge cell. That is, a liquid crystal panel or a plasma display panel may be applied in place of the OLED panel described above, and a method of generating luminance correction data and correcting the luminance of a pixel using the same may be applied even if the display panel is changed.

As described above, the apparatus for generating luminance correction data and the method for generating luminance correction data using the same may reduce the hardware logic for calculating the luminance correction data, thereby increasing the price competitiveness of the product. In addition, the luminance correction method of the organic light emitting display device according to an embodiment of the present invention can improve or prevent image quality distortion caused by the luminance unevenness of the OLED pixel.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive.

The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: luminance correction data generating device 110: intermediate value calculation unit
120: reference value calculation unit 130: output unit
200: organic light emitting display device 210: OLED panel
220: gate driver 230: data driver
240: timing controller 250: memory

Claims (10)

An intermediate value calculator configured to receive the luminance correction values of the first and second points as reference values and calculate intermediate values;
A reference value calculator for checking whether the intermediate value input from the intermediate value calculator is a final value, outputting the intermediate value as a final value, or calculating a new reference value and providing the new reference value to the intermediate value calculator; And
And an output unit for outputting a final value provided from the reference value calculator as luminance correction data of a third point located between the first point and the second point. The method of claim 1,
If the first intermediate value input from the intermediate value calculator is not the final value, the reference value calculator calculates and supplies the new reference value to the intermediate value calculator.
And the intermediate value calculator calculates a second intermediate value using the input new reference value. The method of claim 1,
The intermediate value calculation unit,
And after adding the luminance correction value of the first point and the luminance correction value of the second point, dividing by two, calculating a first intermediate value and providing the first intermediate value to the reference value calculator. The method of claim 3, wherein
If the first intermediate value is not the final value, the reference value calculator calculates and provides a new reference value to the intermediate value calculator.
And the intermediate value calculator calculates a second intermediate value by dividing by 2 after adding the luminance correction value and the first intermediate value of the second point. The method of claim 2,
The intermediate value calculator is configured to calculate the intermediate value until the number of calculations of the intermediate value satisfies X2-X1 = ^2N (X1 is the luminance correction value at the first point, and X2 is the luminance correction value at the second point). Iterate over the median,
And the reference value calculator is configured to output the N-th calculated intermediate value as the final value. (1) calculating an intermediate value by receiving the luminance correction values of each of the first and second points as reference values;
(2) checking whether the input intermediate value is a final value and outputting the input intermediate value as a final value or calculating a new reference value according to a result of checking the final value;
(3) repeating step (1) based on the new reference value if the intermediate value is not the final value; And
(4) if the intermediate value satisfies the result of checking the final value, outputting the final value as luminance correction data of a third point located between the first point and the second point; How to generate data. The method of claim 6,
The step (2) includes the step of calculating the new reference value if the first intermediate value calculated in the step (1) does not satisfy the result of the confirmation of the final value,
The step (3) includes the step of calculating the second intermediate value by repeating the step (1) based on the new reference value. The method of claim 6,
And the step (1) includes adding the luminance correction value of the first point and the luminance correction value of the second point, and then dividing by two to calculate a first intermediate value. The method of claim 8,
Step (2) includes the step of calculating a new reference value if the first intermediate value is not the final value,
Step (3) includes the step of adding the luminance correction value of the second point and the first intermediate value, and then dividing by two to calculate a second intermediate value. The method of claim 7, wherein
In the step (1), the number of calculations of the intermediate value is ^N until X2-X1 = 2 ^N (X1 is the luminance correction value of the first point, and X2 is the luminance correction value of the second point). Repeating the operation;
The step (2) includes the step of outputting the N-th calculated intermediate value as the final value.

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