JP2008008949A - Method of preparing screen correction data in image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preparing screen correction data in image display apparatus capable of obtaining uniform display quality in which the luminance irregularity and color irregularity are suppressed even in a display apparatus which has an in-plane distribution of chromaticity in respective colors of R, G, B with respect to the image display apparatus capable of color display. <P>SOLUTION: The method of preparing screen correction data in image display apparatus which permits a color display by combining a plurality of monochromes including at least three colors of R, G, B comprises: a procedure 1 of displaying the respective monochromes in the whole screen with the image display apparatus and obtaining luminance data and chromaticity data of the respective monochromes every divided small divisions of the screen; a procedure 2 of determining chromaticity correction data every small divisions so as to become a uniform white balance in the whole screen from the chromaticity data obtained by the procedure 1; and a procedure 3 of determining screen correction data that corrects luminances of the respective monochromes every small divisions from the luminance data obtained by the procedure 1 and the chromaticity correction data determined by the procedure 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for creating screen correction data in a color image display device such as an organic EL display device, and more particularly to a method for creating screen correction data for correcting luminance unevenness and color unevenness over an entire screen having a chromaticity distribution. Is.

  As image display devices, liquid crystal (LCD) display devices, organic EL display devices, and the like have been put into practical use, and improvement of image quality is an important issue.

  In an image display apparatus, a method of creating correction data for luminance unevenness and color unevenness and controlling display has been proposed.

  As a conventional example, Patent Document 1 below discloses a method of compensating display unevenness by measuring the luminance of each liquid crystal cell in an LCD display device.

  FIG. 4 is a schematic diagram showing a compensation method for display unevenness of the LCD display device in Patent Document 1. In FIG.

  As shown in FIG. 4, a luminance meter 32 is installed in front of the display panel 31 of the LCD display device, and the luminance data of each liquid crystal cell of the display panel 31 that outputs a test image (for example, full white) is acquired at a predetermined timing. . Based on the luminance data, correction data is calculated via the A / D converter 33 and the arithmetic circuit 34 and stored in the RAM 35. By performing this operation while sequentially moving the luminance meter, data for correcting luminance variations over the entire screen is obtained. Further, by reflecting the correction data of the entire screen on the image data input to the display panel 31, display unevenness due to variations in characteristics of each liquid crystal cell in the display panel 31 is compensated.

  Patent Document 2 discloses a projection type image display apparatus that improves luminance unevenness of the three primary colors red, green, and blue (R, G, B) on the screen and color unevenness caused by superimposing these. .

  FIG. 5 is a block diagram showing a method for creating correction data of the projection-type image display device in Patent Document 2.

A single color of each of R, G, and B colors is displayed on the entire screen 42. The imaging unit 43 captures luminance data of R, G, and B on the screen 42. The screen 42 is divided into hundreds of areas in a grid pattern in advance, and the correction data creation unit 44 calculates brightness unevenness correction data for each color for each area from the captured R, G, B brightness data. The video signal for driving the display element is corrected based on the correction data input to the memory device of the display device. By using the luminance unevenness correction data in this way, color unevenness is corrected.
JP 61-243495 A JP-A-8-328147

  Here, in the case of the method in Patent Document 1 described above, display unevenness due to variations in luminance of each liquid crystal cell is compensated for in the display device, but it is not intended to correct color unevenness particularly in color display.

  In the case of the technique disclosed in Patent Document 2, the precondition is that the chromaticity (emission spectrum) of each color of R, G, and B is almost the same in the entire display region in correcting the color unevenness. This is because in a type using a color filter such as an LCD display device, the chromaticity of the color filter alone has little error in the entire display area, so it is often not a problem even if it is assumed that “the chromaticity is the same over the entire surface”. . Therefore, if even the luminance variation caused by the backlight and the drive circuit can be corrected, the color unevenness can be corrected over the entire display area.

  However, depending on the display device, there may be variations in chromaticity within the display area even when displaying R, G, B colors in a single color. In this case, the above-described method cannot compensate for the color unevenness even if the brightness unevenness of the entire screen can be compensated.

  For example, in an organic EL display device, uneven distribution may occur not only in the luminance of each color of R, G, and B but also in chromaticity due to the non-uniformity of the film forming process. In the organic EL display device, since the light emitting layer of the light emitting device and other functional films are very thin, this uneven brightness and chromaticity are likely to occur. In particular, the chromaticity (emission spectrum) of the organic EL is influenced by the optical interference effect inside the device. For this reason, the film thickness error at the nm level reverses the wavelength that interferes and strengthens and reverses the wavelength that weakens, so that color unevenness tends to occur.

  Therefore, the present invention provides a uniform display quality in which luminance unevenness and color unevenness are suppressed, even in an image display device capable of color display, even if the display device has an in-plane distribution of chromaticity for each of R, G, and B colors. The purpose is to get.

The present invention has been made in view of such problems,
A method for creating screen correction data for an image display device capable of color display by combining a plurality of single colors including at least three colors of R, G, and B,
Procedure 1 for displaying each single color on the entire screen on an image display device and obtaining luminance data and chromaticity data of each single color for each of the divided small sections of the screen;
Procedure 2 for obtaining chromaticity correction data for each small section from the chromaticity data acquired in Procedure 1 so as to achieve uniform white balance over the entire screen;
Procedure 3 for obtaining screen correction data for correcting the luminance of each single color for each small section from the luminance data acquired in Procedure 1 and the chromaticity correction data obtained in Procedure 2;
It is characterized by comprising.

  According to the present invention, in an image display device capable of color display, the luminance and chromaticity of each of the R, G, and B colors are measured and the screen correction data is calculated. Even a display device having a distribution can achieve uniform display quality with reduced brightness and color unevenness.

  Next, embodiments of the present invention will be described below. In this embodiment, an organic EL display device will be described as an example of an image display device.

  FIG. 1 is a diagram showing a screen correction data calculation system to which a screen correction data creation method for an image display device is applied according to an embodiment of the present invention.

  11 is a camera device, 12 is a camera control block, 13 is a system control block, 14 is a calculation block, 15 is a luminance / chromaticity data memory, 16 is a panel control block, 17 is an organic EL display panel, and 18 is a correction data memory. is there. The camera device 11 is, for example, a 3CCD (charge coupled device). The camera control block 12 outputs luminance data and chromaticity data synthesized based on the data from the camera device 11 to the system control block 13. At this time, the emission spectrum data cannot be calculated with, for example, 3CCD, but if R, G, B are measured in advance and a correction table is provided, the calculation can be performed as x, y chromaticity data of the CIE color system. Is possible. The camera device 11 preferably measures the entire effective display area of the organic EL display panel 17 at a time. However, when the resolution of the camera device 11 is insufficient, the effective display area may be divided and measured.

  Next, the flow of screen correction data calculation will be described.

  FIG. 2 is a flowchart showing the flow of the screen correction data calculation procedure.

  First, the organic EL display panel 17 is displayed on the entire surface R (luminance data 100%). The luminance data and chromaticity data at the time of R display are measured by the camera device 11 for each divided small section of the screen of the organic EL display panel 17 and stored in the luminance / chromaticity data memory 15. Similarly, display is performed on the entire surface G (luminance data 100%) to measure the luminance data and chromaticity data, and further displayed on the entire surface B (luminance data 100%) to measure the luminance data and chromaticity data. The data is stored in the data memory 15. This is procedure 1.

  In the luminance / chromaticity data memory 15, as shown in Table 1, the coordinate values of the measurement points and the luminance and chromaticity of each color of R, G, B are stored. The inside of the organic EL display panel 17 is divided into small sections of a predetermined size. In the example of Table 1, all 1000 × 1000 pixels are divided into 100 sections, and 100 × 100 pixels are defined as one section. The center position ((50, 50), (50, 150)...) Of each section is the measurement position. The number of pixels and the number of sections may be other numerical values.

ＥＬ素子では、色度が膜厚にも依存するので、膜厚にムラがあると、輝度だけでなく色度も場所によって異なる。そこで、本発明においては、画面全体を一括してホワイトバランスをとるのではなく、場所毎にホワイトバランスをとる。

In an EL element, since chromaticity depends on the film thickness, if the film thickness is uneven, not only luminance but also chromaticity varies depending on the location. Therefore, in the present invention, white balance is taken for each place instead of white balance for the entire screen at once.

  Hereinafter, how to obtain white balance will be described.

  Assume that the luminance and chromaticity of R at a certain place are measured as luminance = Lr and chromaticity = (Crx, Cry), respectively.

  Similarly, it is assumed that the luminance and chromaticity of G are measured as luminance = Lg and chromaticity = (Cgx, Cgy), and the luminance and chromaticity of B are measured as luminance = Lb and chromaticity = (Cbx, Cby).

  Since the white luminance Lw at the place is the total value of the luminances of the respective colors, it is given by the following equation (1).

Lw = Lr + Lg + Lb (1)
White chromaticity (Cwx, Cwy) is given by the following equations (2) and (3), which are average values of chromaticity weighted by the luminances of R, G, and B.

Cwx = (Lr · Crx + Lg · Cgx + Lb · Cbx) / (Lr + Lg + Lb)
………… (2)
Cwy = (Lr · Cry + Lg · Cgy + Lb · Cby) / (Lr + Lg + Lb)
………… (3)
In this state, when the entire surface is displayed in white, the luminance is not uniform and the color varies depending on the location. That is, it does not become uniform white.

  That is, white where the luminance of R is relatively high and G and B are low luminance is reddish white, and where G is high luminance and R and B are low luminance, greenish white become.

  White balance is to optimize white chromaticity. Since the chromaticity is determined depending on the material of the light emitting element and the film thickness of each place, it is difficult to adjust the chromaticity by making it variable, but the brightness, that is, the luminance is the driving current for each element. Can be adjusted by value. In the above formulas (2) and (3), (Crx, Cry), (Cgx, Cgy), and (Cbx, Cby) are fixed, but changing Lr, Lg, and Lb changes the chromaticity of white. be able to.

  When adjusting the white balance for each location, if the brightness of R is too high compared to G and B, white will be reddish. However, the following method is used here.

The predetermined white chromaticity is (Cnx, Cny).
Cnx = (Lr ′ · Crx + Lg ′ · Cgx + Lb ′ · Cbx) / (Lr ′ + Lg ′ + Lb ′) (2 ′)
Cny = (Lr ′ · Cry + Lg ′ · Cgy + Lb ′ · Cby) / (Lr ′ + Lg ′ + Lb ′) (3 ′)
Is solved as a simultaneous equation for Lr ′, Lg ′, and Lb ′.

  However, since the simultaneous equations have three unknowns and two equations, only the ratio of Lr ′: Lg ′: Lb ′ is determined, and the absolute value of the luminance is not determined.

The absolute value of the luminance is determined so that the entire screen has a uniform luminance when white is displayed on the entire screen. That is, a predetermined uniform white luminance value is Lw0,
Lw0 = Lr ′ + Lg ′ + Lb ′ (1 ′)
The luminances Lr ′, Lg ′, and Lb ′ of each color are determined so that

  When the equations (1 ') to (3') are solved for Lr ', Lg', and Lb ', the absolute value of luminance at each location is determined. When each color emits light with this luminance, the brightness is Lw0 in all places, and the entire screen has a uniform brightness. Further, the chromaticity of white is (Cnx, Cny) in all places, and is aligned to a predetermined white. That is, it is possible to obtain a display that is white balanced and uniform in brightness.

  The luminance values Lr ′, Lg ′, Lb ′ calculated as described above are stored in the correction data memory 18 as chromaticity correction data as shown in Table 2. This is procedure 2.

測定のときには最大輝度の電流を供給したので、Ｌｒ，Ｌｇ，Ｌｂはそれぞれ１００％の階調データに該当する。

Since the maximum luminance current was supplied during measurement, Lr, Lg, and Lb correspond to 100% gradation data, respectively.

  On the other hand, the luminance obtained from (1 ') to (3') is less than that. The gradation data is Lr ′ / Lr × 100 (%) for R, Lg ′ / Lg × 100 (%) for G, and Lb ′ / Lb × 100 (%) for B.

  Gradation data of 0% to 100% input from the outside is converted into gradation data in this range and sent to the display panel. For example, since the maximum luminance for R is Lr '/ Lr × 100 (%), this is again set to a gradation level of 100%, and intermediate gradation data is also converted to gradation data multiplied by Lr' / Lr. Thus, the screen correction is performed by calculating the ratio between the luminance of each color of R, G, B for each small block acquired in step 1 and the luminance of each color of R, G, B for each small block calculated in step 2 as a correction coefficient. Get the data. This is procedure 3.

  FIG. 3 is a block diagram showing a configuration of an EL display device provided with the white balance and luminance correction means of the present invention.

  In FIG. 3, 21 is an organic EL display device, 22 is a screen correction data memory, 23 is an image signal control block, 24 is a panel drive circuit, and 25 is a display panel.

  The correction coefficient that is the screen correction data is stored in the form shown in Table 3 in the screen correction data memory 22 of the organic EL display device 21 shown in FIG.

有機ＥＬ表示装置２１は、各画素へのビデオ信号に対し、画面補正データメモリ２２から各画素へ対応するＲ，Ｇ，Ｂ各色の補正データを取り出し、その補正データをビデオ信号に乗算して、補正済みビデオ信号としてデータ線制御回路に出力する。有機ＥＬ表示装置２１の各画素は、輝度及び色度を補正したビデオ信号をもとに発光する。

For the video signal to each pixel, the organic EL display device 21 takes out correction data for each color of R, G, B corresponding to each pixel from the screen correction data memory 22 and multiplies the video signal by the correction data. The corrected video signal is output to the data line control circuit. Each pixel of the organic EL display device 21 emits light based on a video signal whose luminance and chromaticity are corrected.

  In this way, in the image display device capable of color display, the luminance and chromaticity of each of the R, G, and B colors are measured to calculate the screen correction data, whereby the chromaticity in-plane distribution is obtained for each of the R, G, and B colors. Even with a display device having a large thickness, uniform display quality with reduced luminance and color unevenness can be obtained.

  In the above description, the screen correction data is calculated from the single measurement data. However, the present invention is not limited to this, and the screen correction data is re-calculated by measuring again the output data with reference to the correction data calculated once. May be. By repeating this process several times, correction data can be created with high accuracy.

  In this embodiment, the display panel is divided into small sections of a predetermined size to have correction data. The size of the small section can be set within a range where the luminance and chromaticity are relatively uniform. There are also restrictions on memory capacity and cost.

  If necessary, the R, G, and B correction data may be stored in all pixel units with the small section as one pixel.

  In the above description, the screen correction data calculation is performed at a single luminance.

  The present invention is not limited to this, and the same screen correction data calculation may be performed for each of a plurality of gradations. In a display device that displays up to 255 gradations, the correction data described in this embodiment may be created for each of several gradation levels such as gradation 255, gradation 150, and gradation 50. The correction of intermediate gradation without generating correction data is calculated by linear interpolation based on the correction data possessed by each gradation. This effect makes it possible to obtain uniform display quality even when the luminance unevenness and the color unevenness appear depending on the gradation level.

  In the present embodiment, the image display apparatus for outputting three colors of R, G, and B has been described. However, the present invention is not limited to this. Even if the number of colors increases, the chromaticity calculation when the colors are mixed can be performed in the same manner, and therefore, an image display device capable of outputting three or more colors may be used. For example, the present invention is also applicable to a four-color output level display device of R, G1, G2, and B.

The figure which shows the screen correction data calculation system with which the screen correction data creation method of an image display apparatus is applied in embodiment of this invention. Flowchart showing the procedure of screen correction data calculation flow The block diagram which shows the structure of the organic electroluminescence display provided with the correction means of the white balance and brightness | luminance of this invention Schematic showing a compensation method for display unevenness of a conventional LCD display device A block diagram showing a method of creating correction data of a projection type image display apparatus which is another conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Camera apparatus 12 ... Camera control block 13 ... System control block 14 ... Calculation block 15 ... Luminance / chromaticity data memory 16 ... Panel control block 17 ... Organic EL display panel 18 ... Correction data memory 21 ... Organic EL display apparatus 22 ... Screen correction data memory 23 ... Image signal control block 24 ... Panel drive circuit 25 ... Display panel

Claims (5)

A method for creating screen correction data for an image display device capable of color display by combining a plurality of single colors including at least three colors of R, G, and B,
Procedure 1 for displaying each single color on the entire screen on an image display device and obtaining luminance data and chromaticity data of each single color for each of the divided small sections of the screen;
Procedure 2 for obtaining chromaticity correction data for each small section from the chromaticity data acquired in Procedure 1 so as to achieve uniform white balance over the entire screen;
Procedure 3 for obtaining screen correction data for correcting the luminance of each single color for each small section from the luminance data acquired in Procedure 1 and the chromaticity correction data obtained in Procedure 2;
A method for creating screen correction data in an image display device comprising:   The chromaticity correction data in the procedure 2 is luminance data calculated so that the total value of luminance and the average value of chromaticity obtained by weighting the luminance for each single color in each subsection become constant luminance and white of chromaticity, respectively. The screen correction data of the procedure 3 includes the correction coefficient calculated as a ratio between the luminance of each single color for each small section acquired in the procedure 1 and the luminance of each single color for each small section calculated in the procedure 2 The method of creating screen correction data in the image display device according to claim 1, wherein:   The method for creating screen correction data in the image display device according to claim 1, wherein the screen correction data is calculated for each of a plurality of gradations.   4. The method for creating screen correction data in an image display device according to claim 1, wherein the divided small section of the screen is one pixel.   An organic EL display device comprising a screen correction data memory storing screen correction data obtained by the method for creating screen correction data in the image display device according to claim 1.

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