KR100773017B1 - Method for eliminating noise of horizontal lines and calibrating gamma in OLED panel - Google Patents

Abstract

According to an aspect of the present invention, there is provided an OLED horizontal noise removing and gamma correction method, comprising: setting a black level data value in an OLED device in which color reproduction and brightness levels differ according to R, G, and B input levels; Dividing the OLED display panel into a central region and all other regions, and measuring the A / D output value of the OLED driver IC while increasing the white luminance value for each of the divided regions; Obtaining a slope offset addition coefficient by using the A / D output value and the block level data value of the OLED driver IC for each of the divided regions; Setting the black level data value and slope offset addition coefficient value in a corresponding register of a driver IC; Outputting a white pattern for each horizontal line and measuring an A / D output value of the driver IC to obtain a line offset and to set the offset in the internal SRAM of the driver IC; The OLED driver IC removing the interference noise between lines using the black level, slope offset addition factor and line offset; And measuring gamma values by measuring luminance of each of R, G, and B, calculating luminance region coefficients based on the measured luminance.

Slope Offset, Line Offset, Line Noise, Gamma Adjustment

Description

Method for eliminating noise of horizontal lines and calibrating gamma in OLED panel

1 is a flow chart showing the overall procedure of the OLED horizontal noise cancellation and gamma correction method according to the present invention.

2 is a block diagram showing an internal configuration of an OLED.

3 is a view showing a state in which an OLED display panel is divided into nine regions.

4 shows slope offset measurements in the center region of an OLED display panel.

5 shows slope offset measurements in all areas except the center area of an OLED display panel.

6 shows coefficients Ca and Cb in the central region of an OLED display panel.

7 is a diagram illustrating a process of obtaining a slope offset addition factor.

8 is a view showing a white pattern for each line to measure a line offset, and accordingly, an A / D output value and a correction value of a driver IC.

9 is a diagram illustrating a configuration of a gamma adjustment system according to the present invention.

10A shows high luminance range measurements for R, G, and B. FIG.

10B shows a low luminance range measurement for G. FIG.

11 is a flow chart of gamma adjustment in accordance with the present invention.

12 illustrates a process of calculating a low luminance region coefficient.

FIG. 13 is a diagram illustrating a process of calculating a high luminance range coefficient for R; FIG.

14 is a diagram illustrating a process of calculating a high luminance region coefficient for G;

15 is a diagram illustrating a process of calculating a high luminance region coefficient for B;

FIG. 16 is a graph showing gamma data obtained by gamma calculation of luminance values measured by a specific OLED panel. FIG.

 <Description of the symbols for the main parts of the drawings>

11: OLED panel 12: OLED driver IC

13: microprocessor 14: SDRAM

15: flash memory 21: PC

22: color analyzer 23: probe

24: target device

The present invention relates to organic light emitting diodes (OLED) horizontal noise removal and gamma correction method, and in particular, to remove line noise of OLED devices having different color temperature and brightness levels for each module, and uniformly to the color temperature and brightness levels required by the user. The present invention relates to a method for automatically adjusting OLED horizontal noise cancellation and gamma correction.

Gamma adjustment refers to the ability to correct the brightness level of relatively dark scenes when viewing in a brightly lit room. For example, when watching a movie, night scenes that are beautifully reproduced in a dark room may not be fully reproduced with the subtle light and darkness of the image when viewed in a bright room at home.

However, in the related art, gamma adjustment is performed with R (Red), G (Green), and B (Blue) output values including noise values due to interference between horizontal lines, so that the color representation of the image is uneven and noise between lines is reduced. Problems that look serious occurred.

The present invention has been made to solve the above problems, the present invention is to remove the line noise of the OLED device, OLED horizontal noise removal and gamma correction method that can be automatically uniformly adjusted to the color temperature and brightness level required by the user The purpose is to provide.

OLED horizontal noise cancellation and gamma correction method according to the present invention comprises the steps of setting a black level data value; Dividing the OLED display panel into a central region and all other regions, and measuring the A / D output value of the OLED driver IC while increasing the white luminance value for each of the divided regions; Obtaining a slope offset addition coefficient by using the A / D output value and the block level data value of the OLED driver IC for each of the divided regions; Setting the black level data value and slope offset addition coefficient value in a corresponding register of a driver IC; Outputting a white pattern for each horizontal line and measuring an A / D output value of the driver IC to obtain a line offset and to set the offset in the internal SRAM of the driver IC; The OLED driver IC removing the interference noise between lines using the black level, slope offset addition factor and line offset; And measuring gamma values by measuring luminance of each of R, G, and B, calculating luminance region coefficients based on the measured luminance.

The slope offset of the center region is characterized by measuring the A / D output value of the driver IC until the A / D output value of the driver IC measured while increasing the white luminance value by the predetermined value a becomes a predetermined value b.

The slope offset of all regions except the center region is a white luminance value obtained by subtracting a predetermined value c from a white luminance value when the A / D output value of the driver IC exceeds a predetermined value b, and the A / D of the driver ICs of the entire region. It is characterized by measuring the output value.

The line offset may be a value obtained by subtracting the A / D output value of the corresponding line from the maximum value of the A / D output values of the driver ICs for all horizontal lines.

The line offset may be moved and stored from an internal memory of the OLED driver IC to a flash memory.

The adjusting of the gamma value may include: initializing the OLED driver IC and setting a linear gamma value, and then storing the expected white pattern luminance value in the final gamma adjustment in an internal memory of the OLED driver IC; Setting a contrast intermediate value for R (Red) and measuring the luminance value of R in the high luminance region; Setting a contrast medium value for G (Green) and measuring the luminance value of G in the high luminance region and the luminance value of G in the low luminance region; Setting a contrast intermediate value for B (Blue) and measuring the luminance value of B in the high luminance region; Calculating coefficients of a low luminance region and coefficients of a high luminance region of each R, G, B with the measured luminance values of each R, G, B; Calculating gamma values of R, G, and B using the coefficients of the low luminance region and the coefficients of the high luminance region and storing the calculated gamma values in an internal memory of a driver IC; The gamma value of each of R, G, and B may be moved to and stored in a flash memory.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

1 is a flow chart showing the overall procedure of the OLED horizontal noise removal and gamma correction method according to the present invention, Figure 2 is a block diagram showing the internal configuration of the OLED.

As shown in FIG. 1, the OLED horizontal noise removing and gamma correction method according to the present invention measures a black level value of the OLED (S1), and measures and calculates a slope offset. (S2), the line offset of the horizontal line (Line) of the OLED is measured to remove the interference noise between the horizontal lines (S3), and finally, the luminance of each of the R, G, B by measuring the gamma In step S4, adjustment is performed.

As shown in FIG. 2, the OLED is an OLED panel 11, an OLED driver IC 12 that supplies R, G, and B signals to the OLED panel 11, and a microcontroller that controls the OLED driver IC 12. It consists of a processor 13, an SDRAM 14 which is a storage device, and a flash memory 15.

Hereinafter, a process from black level measurement to noise cancellation between OLED lines will be described.

First, the microprocessor 13 resets the driver IC 12 and initializes the driver IC 12 through a serial port interface (SPI). Then, the linear gamma values 0 to 1023 are set in the SRAM 14 inside the driver IC 12 through SPI for luminance measurement.

In the process of obtaining the black level data, when the input signal is applied, clamp D / A data is set to 8 (about 0.7 to 0.8%) from the initial value 800 (about 75 to 80% of the clamp level). While reducing, the A / D (Analog to Digital) output data of the OLED driver IC 12 is measured, wherein the measured A / D output value is the initial A / D output value and 4 (0.3 to 0.5% of the A / D output). The black level data is defined by adding the constant 128 (approximately 12 to 13%) to the clamp D / A data when an abnormal difference occurs. Hereinafter, the black level measurement value will be referred to as BAD.

Next, the slope offset is divided into nine regions of the OLED display panel 11 as shown in FIG. 3, and then the A / A of the driver IC 12 is increased while increasing only the white luminance component in the divided regions. Measure the D output value. Here, the slope offset measurement is performed by dividing the center area measurement and the full area measurement.

First, as shown in FIG. 4, the slope offset in the center region is measured until the A / D output value of the driver IC 12 becomes constant 768 while increasing the white luminance value by four. The CAD3 to CAD9F values in the table represent measured values of the A / D output of the driver IC 12.

As shown in FIG. 5, the slope offset in all regions except the center region is the white luminance obtained by subtracting the constant 16 from the white luminance when the A / D output value of the driver IC 12 exceeds the constant 768 value. The A / D output value of the driver IC 12 corresponding to the value is measured.

For example, if the white luminance value at the time when the A / D output value of the driver IC 12 exceeds the constant 768 value is 0x43, the white luminance value 0x43 minus 0x10, i. Measure A / D output value of 12). In the table, AAD1 to AAD9 represent A / D output measurements of the driver IC 12.

Next, SOACa, SOACb, and SOACc which are slope offset addition coefficients are obtained.

In order to calculate the slope offset addition coefficients, coefficients Ca and Cb in the central region are obtained by the table shown in FIG. In the table, BAD is a black level measurement.

As shown, in order to obtain the center area coefficients Ca and Cb, the variables SAD1, SADx, SADxx, SADy, and SADxy, which are combined by subtracting the black level measurement value from the A / D output value according to the white luminance input value, are expressed as follows. Obtained by

The formulas for obtaining the coefficients Ca and Cb in the central region are as follows.

The slope offset addition coefficients SOACa, SOACb, and SOACc, which are obtained using the coefficients Ca and Cb of the center region obtained as described above, are obtained by the equation shown in FIG. Where BAD is the black level measurement.

FIG. 8 is a view showing a white pattern for each line to measure a line offset, and correspondingly, an A / D output value and a correction value of the driver IC 12.

In order to measure the line offset of the entire OLED line, the black level measurement value and the slope offset addition coefficient value obtained in the above process are set in the corresponding register of the driver IC 12. The A / D output value of the driver IC 12 is measured by outputting a white pattern (Pattern) one line for a total of 218 horizontal lines of OLED (different panels).

At this time, a value obtained by subtracting the A / D output value of the corresponding line from the maximum value among the A / D output values of the driver IC 12 is defined as a correction value. The correction value of the corresponding line for all the lines is stored in the internal memory (SRAM) of the OLED driver IC 12. When the target device is not powered, the line correction value stored in the internal memory of the driver IC 12 is erased. Finally, the flash memory 15 is stored in a flash memory 15 in order to prevent it from being stored.

Then, the driver IC 12 may remove the inter-line interference noise by using the black level measurement value, the slope offset addition coefficient value, and the correction value.

9 is a diagram illustrating a configuration of a gamma adjustment system according to the present invention.

As shown, the gamma adjustment system is composed of a computer (PC) 21, a color analyzer 22, a probe 23, and a target device 24. The target device 24 refers to a display element such as a portable multimedia player (PMP), a PDA, an OLED, a TV, or the like.

First, when the probe 23 measures color coordinate (x, y) and luminance (Lv) values of the target device 24 and transmits the values to the color analyzer 22, the color analyzer 22 measures the measured color coordinates. The (x, y) and luminance (Lv) values are digitized and transferred to the computer (PC) 21 through the USB interface.

The computer (PC) 21 functions to initialize the OLED driver IC 12, set a linear gamma, and control luminance for each RGB through a USB interface. In addition, the color analyzer 22 transmits the measured color coordinates (x, y) and luminance (Lv) measured values to the target device 24 and performs a white pattern command.

When the color coordinate (x, y) and luminance (Lv) measurements received from the computer 21 for each RGB are stored in the target device 24, the target device 24 uses its own gamma adjustment algorithm. After performing the calculation internally, the gamma value unique to the OLED panel is set in the internal SRAM of the OLED driver IC 12. When the target device 24 is not powered on, the gamma value inherent to the OLED panel stored in the SRAM of the OLED driver IC 12 is erased, and thus the gamma value is finally stored in the flash memory 15. Save it.

Meanwhile, in the present invention, luminance measurement for gamma adjustment is performed by dividing into a high luminance region measurement and a low luminance region measurement.

When the high luminance region is determined 0.1cd / in m ² 60cd / m ² luminance of the white (White) The 8bit (0 ~ 255) in a region having a luminance value between (about 50 to 55% of the total intensity), The luminance (HYR, HYG, HYB) for each RGB (Red, Green, Blue) is measured with a color analyzer while increasing the white luminance from 0x0F to 0xFF by 0x10.

On the other hand, the low luminance region measurement indicates that the luminance component of the white is 8 bits (0 to 255) in the region having a luminance value between 0.1 cd / m ² and 4 cd / m ² (about 3 to 4% of the total luminance). When the white luminance initial value 0x17 to 0x8F is increased by 0x04 in increments of 0x04, the luminance LYG is measured only with respect to G (Green) by the color analyzer 22.

In this case, the luminance measurement is performed in order of high luminance region measurement for R, high luminance region measurement for G, low luminance region measurement for G, and high luminance region measurement for B.

The process of measuring the brightness is as follows.

As described above with reference to FIG. 2, the driver IC 12 is first reset, and the driver IC 12 is initialized through the serial port interface (SPI). Then, the black level, slope offset and line correction value are set in the internal register of the driver IC 12 to remove the line interference noise, and then the linear gamma values (0 to 1023) are measured through the SPI for luminance measurement. It is set in the SRAM inside the driver IC 12. The expected white pattern luminance at the time of final gamma adjustment is stored in the target device 24.

First, the intermediate value is set in the contrast resist for R of the driver IC 12 through SPI and the value of 0 is set in the contrast resist for G and B through the SPI.

And, the luminance measurement for R performs a high luminance region measurement. High luminance region is determined to increment of the output value of the white luminance microprocessor 0x10 (hex 10: 16) to set to a region of high luminance value (brightness value between 60cd / m ² at 0.1cd / m ²⁾ for each of R It measures with the color analyzer 22. Here, when the measured luminance value is 60 cd / m ² or more, the HYR value is stored as a value of zero. The measurement is stored in the internal memory of the target device 24, which is as shown in FIG.

Next, an intermediate value is set in the contrast resist for G of the driver IC 12 and a value of 0 is set in the contrast resist for R and B through the SPI.

In addition, the luminance measurement for G performs the high luminance region measurement and the low luminance region measurement. The high luminance area measurement for G is first performed, the method being the same as the high luminance area measurement for R, and the measurement is as shown in FIG.

Subsequently, a low luminance area measurement is performed on G. The increase in the white luminance output value of the microprocessor is set to 0x4 (decimal: 4) so that the low area luminance value (0.1 cd / m ² to 4 cd / m) for each G is set. luminance value between m ² ) is measured by the color analyzer 22. Here, when the measured luminance value is 4 cd / m ² or more, the LYG value is stored as a value of zero. In addition, the measured values are stored in the internal memory of the target device 24 as shown in FIG.

Next, an intermediate value is set in the contrast resist for B of the driver IC 12 through SPI, and a value of 0 is set in the contrast resist for R and G.

And, the luminance measurement for B performs a high luminance region measurement, the method is the same as the high luminance region measurement for R and the measurement is as shown in Fig. 10.a.

The flowchart of the gamma adjustment described above is shown in FIG. 11. In summary, the OLED driver IC 12 is reset and initialized, and then the black level value, the slope offset, the line offset, and the linear gamma value are set (S31). Then, set the intermediate contrast value for R (S32) to measure the high luminance region (S33), set the contrast medium value for G (S34) and measure the high luminance region and the low luminance region (S35, S36). ), A median contrast for B is set (S37) and a high luminance region is measured (S38) to calculate gamma (S39). The calculated gamma value is set in the driver IC 12 and stored in the flash memory 15 (S40). As above, the luminance for R, G, and B is measured, and then the intrinsic gamma of the OLED panel is calculated.

In order to obtain the gamma value, first, a linear gamma increase value is obtained in each luminance region measurement. In the measurement of the high luminance region, the equation for calculating the linear gamma value increase value with respect to the increase value 0x10 of the white luminance input value is as follows.

Linear gamma maximum value (0x3FF): White luminance maximum value (0xFF) = Linear gamma increase value: White luminance increase value (0x10)

Therefore, the linear gamma increase value in the high luminance region is Ox40.

In the low luminance region measurement, the equation for calculating the linear gamma value increase value with respect to the increase value (0x4) of the white luminance input value is as follows.

Linear gamma maximum value (0x3FF): White luminance maximum value (0xFF) = Linear gamma increase value: White luminance increase value (0x4)

Therefore, the linear gamma increase in the low luminance region is Ox10.

The coefficient of each luminance region is obtained using the linear gamma increase value thus obtained.

12 is a view illustrating a process of calculating a low luminance region coefficient.

As shown, SLYG1, SLYGx, SLYGxx, SLYGxy, and SLYGy can be obtained by combining the SLYG (Sum Low Luminance Green) variable values by combining the luminance values of the low region for G according to the respective white luminance input values.

The low luminance region coefficient value CLG is obtained using SLYG1, SLYGx, SLYGxx, SLYGxy, and SLYGy as follows.

FIG. 13 is a diagram illustrating a process of calculating a high luminance region coefficient for R. FIG.

As shown, SHYR (Sum High Luminance Red) variable values are obtained by combining the luminance values of the high region with respect to R according to each of the white luminance input values.

When the high luminance region coefficient values CHRa and CHRb are obtained using the SHYR1, SHYRx, SHYRxx, SHYRxy, and SHYRy, they are as follows.

14 is a diagram illustrating a process of calculating a high luminance region coefficient for G.

As shown, SHYG1, SHYGx, SHYGxx, SHYGxy, and SHYGy can be obtained by combining SUMG (Sum High Luminance Green) variable values by combining luminance values of the high region for G according to the white luminance input values.

The high luminance region coefficient values CHGa and CHGb are obtained using the SHYG1, SHYGx, SHYGxx, SHYGxy, and SHYGy as follows.

15 is a diagram illustrating a process of calculating a high luminance region coefficient for B. FIG.

As shown, SHYB (Sum High Luminance Blue) variable values are obtained by combining the luminance values of the high region for B according to each of the white luminance input values, thereby obtaining SHYB1, SHYBx, SHYBxx, SHYBxy, and SHYBy.

When the high luminance region coefficient values CHBa and CHBb are obtained using the SHYB1, SHYBx, SHYBxx, SHYBxy, and SHYBy, they are as follows.

Next, the gamma of the OLED is calculated using the low luminance area coefficients obtained as described above and the high luminance area coefficients of R, G, and B, respectively.

First, the gamma value for R is obtained by the following equation.

Second, the gamma value for G is obtained by the following equation.

Third, the gamma value for B is obtained by the following equation.

FIG. 16 is a graph illustrating gamma data obtained by calculating a luminance value measured by a specific OLED panel using the above formula.

As described above, the gamma calculated data value is stored in the internal memory (SRAM) of the OLED driver IC 12, and stored in the internal memory of the OLED driver IC 12 when there is no power supply of the target device 24. In order to prevent the gamma adjustment value from being erased, it is finally stored in the flash memory 15.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

The OLED horizontal noise removal and gamma correction method according to the present invention can greatly reduce noise components between lines of an OLED display, and perform gamma adjustment in a state in which interference between signals is eliminated between lines, thereby making color representation of an image more natural. Can be. In addition, the color temperature and brightness level desired by the user is different depending on the market situation, and by setting the color temperature and brightness level required by the user by the OLED line noise removal and gamma adjustment method according to the present invention, it is automatically adjusted to the market situation It can be shipped uniformly suitably.

Claims (6)

In an OLED device in which color reproduction and brightness levels differ from module to module according to the R, G, and B input levels, Setting a black level data value; Dividing the OLED display panel into a central region and all other regions, and measuring the A / D output value of the OLED driver IC while increasing the white luminance value for each of the divided regions; Obtaining a slope offset addition coefficient by using the A / D output value and the block level data value of the OLED driver IC for each of the divided regions; Setting the black level data value and slope offset addition coefficient value in a corresponding register of a driver IC; Outputting a white pattern for each horizontal line and measuring an A / D output value of the driver IC to obtain a line offset and to set the offset in the internal SRAM of the driver IC; The OLED driver IC removing the interference noise between lines using the black level, slope offset addition factor and line offset; Measuring luminance of each of R, G, and B, and calculating gamma values by calculating luminance region coefficients based on the measured luminance. The method of claim 1, The slope offset of the center region is measured by increasing the white luminance value by a predetermined value a until the A / D output value of the driver IC measured by the predetermined value b is measured. How to remove horizontal noise and correct gamma. The method of claim 1, The slope offset of all regions except the center region is a white luminance value obtained by subtracting a predetermined value c from a white luminance value when the A / D output value of the driver IC exceeds a predetermined value b, and the A / D of the driver ICs of the entire region. OLED horizontal noise cancellation and gamma correction method characterized by measuring the output value. The method of claim 1, And the line offset is a value obtained by subtracting the A / D output value of the corresponding line from the maximum value of the A / D output values of the driver ICs for all the horizontal lines. The method of claim 4, wherein And the line offset is shifted and stored from an internal memory of the OLED driver IC to a flash memory. The method of claim 1, Adjusting the gamma value, After initializing the OLED driver IC and setting the linear gamma value, storing the expected white pattern luminance value at the time of the final gamma adjustment in the internal memory of the OLED driver IC; Setting a contrast intermediate value for R (Red) and measuring the luminance value of R in the high luminance region; Setting a contrast medium value for G (Green) and measuring the luminance value of G in the high luminance region and the luminance value of G in the low luminance region; Setting a contrast intermediate value for B (Blue) and measuring the luminance value of B in the high luminance region; Calculating coefficients of a low luminance region and coefficients of a high luminance region of each R, G, B with the measured luminance values of each R, G, B; Calculating gamma values of R, G, and B using the coefficients of the low luminance region and the coefficients of the high luminance region and storing the calculated gamma values in an internal memory of a driver IC; And shifting and storing the gamma values of the R, G, and B data into a flash memory.

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