JP2005283908A - Method for extending sticking life of display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for extending sticking life of a display which extends the sticking life of the display. <P>SOLUTION: In the method for extending the display having a function for combining a fixed pattern with an input video image and displaying it, which is used for a display device and causes emission luminance deterioration according to display luminance and display time, aging processing of the display is performed at a state that a simple reserve video of the fixed pattern is displayed on the display. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a method for extending the life of a display that causes deterioration in light emission luminance according to display luminance and display time, such as an organic EL panel, an inorganic EL panel, and a PDP, and in particular, a fixed pattern is synthesized with an input video. The present invention relates to a method for prolonging the life of a display used in a display device having a function of displaying information.

  In the organic EL element, the light emission luminance decreases according to the drive current amount and the display time. For this reason, in a digital camera or a mobile phone using an organic EL panel as a display panel, there is a problem that a burn-in phenomenon occurs when the same image such as an icon is continuously displayed.

  FIG. 1 shows a deterioration characteristic SL of an organic EL element when a low-luminance image such as a background is continuously displayed, and a deterioration characteristic SH of an organic EL element when a high-luminance image such as characters is continuously displayed. Show.

  As shown in FIG. 2A, it is assumed that a character M (fixed pattern, icon) is displayed in an arbitrary background H. In this example, when the gradation is represented by 8 bits (the higher the gradation is, the higher the luminance is), the luminance of the character portion M is 192 gradations. The luminance of the background portion H has various gradations, but in this example, it is 64 gradations.

  If it is assumed that various images are displayed in the background portion H, it is considered that the background portion H is generally a solid image even though the average luminance is large or small. When such a fixed pattern continues to be displayed for a long period of time and then an all-white image is displayed, the luminance deterioration of the pixel where the character M is displayed is larger than the luminance deterioration of the pixel where the background H is displayed. As shown in FIG. 2B, the luminance of the pixel MG on which the character M is displayed is comparable to that of, for example, 64 gradations, whereas the pixel HG on which the background H is displayed. The brightness of the image becomes the same level as that of 192 gradations, and the character portion is visually recognized as a burn-in image.

As shown in FIG. 1, the period until the difference between the deterioration rates of two adjacent pixels reaches a limit width (image-recording visibility limit width) ΔQ _{LIM at} which the image-sticking phenomenon becomes visible is shown. It is called a life span.

  An object of the present invention is to provide a method for extending the life of seizure of a display that can prolong the life of seizure of the display.

  The invention according to claim 1 is a method for extending the life of a display which is used in a display device having a function of combining and displaying a fixed pattern on an input image and causing deterioration in light emission luminance in accordance with display luminance and display time. The display aging process is performed in a state in which a simple inverted image of a fixed pattern is displayed on the display.

  The invention according to claim 2 is a method for extending the life of a display that is used in a display device having a function of combining and displaying a fixed pattern on an input image and that causes emission luminance deterioration depending on display luminance and display time. , A simple inverted video of a fixed pattern is generated as a first inverted image, and the image data of the first inverted video is reduced so that the luminance of the lowest luminance portion of the obtained first inverted video is 0. A second inverted video shifted to the luminance side is generated, and the display aging process is performed in a state where the second inverted video is displayed on the display.

  According to a third aspect of the present invention, there is provided a method for extending the life of a display which is used in a display device having a function of synthesizing and displaying a fixed pattern on an input image and which causes a deterioration in light emission luminance according to display luminance and display time. , A simple inverted video of a fixed pattern is generated as a first inverted image, and the image data of the first inverted video is reduced so that the luminance of the lowest luminance portion of the obtained first inverted video is 0. A second inverted video shifted to the luminance side is generated, and the image data of the second inverted video is gain-adjusted so that the luminance value of the highest luminance portion of the second inverted video becomes the maximum luminance value. The display is aged, and the display is subjected to the aging process with the third inverted video displayed on the display.

  In the invention according to claim 4, in the invention according to claims 1 to 3, when there are a plurality of types of fixed patterns to be displayed on the display, the frequency of appearance of each fixed pattern is considered and A fixed pattern composite image is generated, and a simple reverse image of the obtained composite image is used as a fixed pattern simple reverse image.

  According to the present invention, the burn-in life of the display can be extended.

  Hereinafter, with reference to FIGS. 3 to 9, an embodiment in which the present invention is applied to an organic EL panel used in a display device having a function of combining and displaying a fixed pattern on an input image will be described.

[1] Description of the basic concept of the present invention In the organic EL panel, the organic EL panel is applied with a voltage before being shipped as a product for the purpose of stably outputting the image. The EL panel is deteriorated. Thus, degrading the organic EL panel in advance is called aging.

  In the present invention, the organic EL panel used in a display device having a function of synthesizing and displaying a fixed pattern (icon) on the input image is subjected to special aging that is different from usual, and the organic EL panel is printed. The service life is extended. In other words, the image pattern displayed on the organic EL panel at the time of aging is made to be a pattern different from normal aging, thereby extending the burn-in life of the organic EL panel.

  FIG. 3A shows an example of an image when an icon (fixed pattern) is displayed. The position where the icon (fixed pattern) is displayed is fixedly determined. In this example, the icon A is composed of characters “TV”. Assuming that the input video signal is represented by 8 bits, the video signal value of the background H is 64, for example, and the image data of the icon A is 192, for example. If such an icon is continuously displayed, as described above, the deterioration rate of the organic EL corresponding to the display position of the high-luminance icon becomes larger than the deterioration rate of the organic EL of the low-luminance background portion. The seizure phenomenon will occur.

  Therefore, the reverse image of the icon image is displayed on the organic EL panel at the time of aging, and the reverse image is printed. That is, the deterioration rate of the background portion is made larger than the deterioration rate of the icon portion by aging using the reverse video.

  FIG. 3B shows the reverse image of FIG. In the reverse video, the video signal value of the background H is 191 (= 255-64), and the image data of the icon A is 63 (= 255-192).

  FIG. 4 shows the deterioration rate characteristics of an organic EL panel subjected to aging using an inverted image.

  In FIG. 4, SL is a deterioration characteristic SL of the organic EL element when the background image of low luminance is continuously displayed, and a deterioration characteristic SH of the organic EL element when the image of the high luminance icon is continuously displayed. Is shown.

At the start of use of the organic EL panel, the deterioration rate in the region (background region) where the low-luminance background image is displayed is larger than the deterioration rate in the region (icon region) where the high-luminance icon image is displayed. It has become. When the organic EL panel is used, the deterioration rate per hour in the icon region is larger than the deterioration rate per short time in the background region, so the deterioration rate in both regions gradually becomes equal, and After the two deterioration rates become equal, the deterioration rate of the icon area gradually becomes larger than the deterioration rate of the background area, and the difference between the deterioration rates reaches the burn-in visual recognition limit width ΔQ _LIM. .

  Comparing FIG. 1 and FIG. 4, it can be seen that the seizure life is longer in the case of performing the aging using the reverse image as in the present embodiment.

As shown in FIG. 4, the aging using the reverse video is a region (icon region) in which a deterioration rate in a region (background region) where a low-luminance background image is displayed and a high-luminance icon image is displayed. difference Delta] Q ₀ of the deterioration rate on until a value close to Delta] Q _LIM below seizing visual threshold width Delta] Q _LIM, it is preferable to perform. This is because if ΔQ ₀ becomes larger than ΔQ _LIM , the seizure phenomenon is visually recognized immediately after the start of use.

The time until ΔQ ₀ becomes substantially equal to ΔQ _LIM (aging time using an inverted image) is calculated based on the deterioration characteristic when the deterioration characteristic of the organic EL panel is known in advance. When the deterioration characteristics of the organic EL panel are unknown, the deterioration rate of the background area and the deterioration ratio of the icon area are monitored with an optical measuring instrument during aging, and the difference ΔQ ₀ between the two is the burn-in visibility limit. Aging may be performed until the width ΔQ _LIM becomes substantially equal.

  Instead of a simple inverted video (simple inverted video) as shown in FIG. 3B, as shown in FIG. 3C, a simple inverted video so that the minimum image data value of the simple inverted video is 0. Inverted video (low-level inverted video) obtained by shifting each image data value to the lower level side may be used. In FIG. 3B, since the image data of the icon A is the smallest, in the low-level inverted image shown in FIG. 3C, the image data of the icon A is 0 and the video signal value of the background H is 128 (= 191-63).

  When aging is performed using such a low-level inverted video, the deterioration rate of the entire organic EL panel at the end of aging can be suppressed lower than when aging is performed using a simple inverted video. it can.

  Further, as shown in FIG. 3 (d), an inverted video (low level and gain) obtained by adjusting the gain of each image data of the low level inverted video so that the highest image data value of the low level inverted video is 255. (Adjusted reverse video) may be used. In FIG. 3C, since the image data of the background H is the smallest, the image data of the background H is 255 and the image data of the icon A is 0 in the low level and gain adjustment inverted image shown in FIG. It becomes.

  When aging is performed using such a low-level and gain-adjusted inverted video, the aging time can be shortened compared to when aging is performed using a low-level inverted video.

  It should be noted that only aging using inverted video (low-level inverted video, low-level and gain-adjusted inverted video) may be performed, or after normal aging, reverse video (low-level inverted video, low-level inverted video, low-level inverted video) Aging using leveling and gain adjustment inverted video) may be performed.

[2] In the above [1], the case where only one type of icon (fixed pattern) exists has been described, but usually there are a plurality of types of icons that can be displayed. Therefore, a method of generating a reverse video (simple reverse video, low-level reverse video and low-level and gain adjustment reverse image) used for aging when there are a plurality of displayable icons will be described.

  Here, a case will be described in which there are two types of icons, such as the icon shown in FIG. 5A and the icon shown in FIG. Assume that the input video signal is represented by 8 bits.

  The first icon A1 shown in FIG. 5A is a circular image, and the image data is 255. The video signal value of the first background H1 is 128. The second icon A2 shown in FIG. 5B is a rectangular image, and its image data is 255. The video signal value of the second background H2 is 128.

  When a plurality of icons are prepared in this way, a combined image of these icon images is generated in consideration of the ratio (display frequency) at which those icons are displayed.

  First, a case where the ratio between the display frequency of the first icon (the number of display frames per unit time) and the display frequency of the second icon is 1: 1 will be described. When the ratio between the display frequency of the first icon (the number of display frames per unit time) and the display frequency of the second icon is 1: 1, the composite image is as shown in FIG.

  The composite image of the first icon image and the second icon image includes an icon area A11 that does not overlap the second icon A2 in the first icon A1, and an icon area that overlaps the first icon A1 and the second icon A2. A 12, an icon area A 22 that does not overlap the first icon A 1 in the second icon A 2, and a background area H 12.

  When the display ratio of the first icon and the second icon is 1: 1, the image data value of the icon area A11 is obtained by multiplying the image data value (255) of the first icon A1 by 1/2. The sum (192) of the value (255/2) and the value (128/2) obtained by multiplying the image data value (128) of the second background H2 by 1/2. The image data value of the icon area A22 is 1/2 of the value (64/2) obtained by multiplying the image data value (64) of the second icon A2 by 1/2 and the image data value (128) of the first background H1. The sum (96) with the value (128/2) multiplied by.

  The image data value of the icon area A12 is half the image data value (255/2) obtained by multiplying the image data value (255) of the first icon A1 by 1/2 and the image data value (64) of the second icon A2. The sum (160) with the value (64/2) multiplied by. The image data value of the background region H12 is a value (128/2) obtained by multiplying the image data value (128) of the first background H1 by 1/2, and the image data value (128) of the second background H2 is 1/2. The sum (128) with the value (128/2) multiplied by.

  Then, as shown in FIG. 6B, a simple inverted image of the composite image is generated. In the simple inverted image, the image data value of the icon area A11 is 63, the image data value of the icon area A22 is 159, the image data value of the icon area A12 is 95, and the image data value of the background area H12 is 127.

  The low-level inverted video is as shown in FIG. In the low-level inverted image, the image data value of the icon area A11 is 0, the image data value of the icon area A22 is 96, the image data value of the icon area A12 is 32, and the image data value of the background area H12 is 64. Become.

  The low level and gain adjustment inversion video is as shown in FIG. In the low-level and gain adjustment inverted image, the image data value of the icon area A11 is 0, the image data value of the icon area A22 is 255, and the image data value of the icon area A12 is 85 (= 32 × 255/96). The image data value of the background area H12 is 170 (= 64 × 255/96).

  Next, a case where the ratio between the display frequency of the first icon (the number of display frames per unit time) and the display frequency of the second icon is 1: 3 will be described. When the ratio between the display frequency of the first icon (the number of display frames per unit time) and the display frequency of the second icon is 1: 3, the composite image is as shown in FIG.

  The image data value of the icon area A11 is 3/4 of the image data value (255/4) obtained by multiplying the image data value (255) of the first icon A1 by 1/4 and the image data value (128) of the second background H2. The sum (160) with the value obtained by multiplying (128 × 3/4). The image data value of the icon area A22 is 3/4 of the value (128/4) obtained by multiplying the image data value (128) of the first background H1 by 1/4 and the image data value (64) of the second icon A2. The sum (80) with the value obtained by multiplying (64 × 3/4).

  The image data value of the icon area A12 is 3/4 of the value (255/4) obtained by multiplying the image data value (255) of the first icon A1 by 1/4 and the image data value (64) of the second icon A2. The average value (112) with the value obtained by multiplying (64 × 3/4). The image data value of the background region H12 is 3/4 of the value (128/4) obtained by multiplying the image data value (128) of the first background H1 by 1/4 and the image data value (128) of the second background H2. Is the sum (128) of the value multiplied by (128 × 3/4).

  Then, as shown in FIG. 7B, a simple inverted image of the composite image is generated. In the simple inverted image, the image data value of the icon area A11 is 95, the image data value of the icon area A22 is 175, the image data value of the icon area A12 is 143, and the image data value of the background area H12 is 127.

  The low-level inverted video is as shown in FIG. In the low-level inverted image, the image data value of the icon area A11 is 0, the image data value of the icon area A22 is 80, the image data value of the icon area A12 is 48, and the image data value of the background area H12 is 32. Become.

  The low level and gain adjustment inversion video is as shown in FIG. In the low level and gain adjustment inverted image, the image data value of the icon area A11 is 0, the image data value of the icon area A22 is 255, and the image data value of the icon area A12 is 153 (= 48 × 255/80). The image data value of the background area H12 is 102 (= 32 × 255/80).

[3] Explanation of optimization of aging time [3-1] When a composite image of an icon is an image as shown in FIG. 6A, a simple inverted video as shown in FIG. 6B is used. The aging time optimization when aging is performed will be described.

It is assumed that the deterioration rate characteristic of the organic EL panel shortens the lifetime at a ratio of 1.4 to the increase in luminance. Further, as shown by a curve S (255 gradations) in FIG. 8, when the initial condition is 255 gradations, it is assumed that the luminance is 100 cd / m ² and has a half-life of 1000H. Further, it is assumed that the seizure visual recognition limit width is 10 gradations.

A case where the γ value of the γ characteristic is 1.0 will be described. The luminance difference corresponding to the burn-in visual recognition limit width (10 gradations) is about 4 {= 100 × (10/255)} cd / m ² . When aging is performed using the simple inverted image of FIG. 6B, the luminance difference is the largest between the area A22 with the maximum gradation 160 and the area A11 with the minimum gradation 63. The luminance of 160 gradations is about 63 {= 100 × (160/255)}, and the luminance of 63 gradations is about 25 {= 100 × (63/255)}.

Therefore, the half-life when the luminance is 63 (160 gradations) is (100/63) ^1.4 × 1000 = 1910, and the half-life when the luminance is 25 (63 gradations) is (100/25 ) ^1.4 × 1000 = 6904

  Based on this result and the curve S (255 gradations) in FIG. 8, as shown in FIG. 8, the deterioration characteristic curve S (160 gradations) in the case of 160 gradations and 63 gradations are shown. A deterioration characteristic curve S (63 gradations) is created.

Based on the deterioration characteristic curve S (160 gradations) and the deterioration characteristic curve S (63 gradations), the time when the difference between the deterioration rates is 4 cd / m ² is defined as the aging time.

  When the curve S (255 gradations) is formulated in advance, the luminance difference corresponding to the burn-in visual recognition limit width (10 gradations), the luminance is 63 (160 gradations), and the luminance is 25 (63 The optimization time can be derived based on the lifetime at the time of (gradation).

[3-1] Optimizing the aging time when aging is performed using a simple inverted video as shown in FIG. 6C when the composite image of the icon is an image as shown in FIG. The conversion will be described.

The deterioration rate characteristic of the organic EL panel is assumed to be shortened by a power of 1.4 every time the luminance increases by 1 cd / m ² . Further, as shown by the curve S (255 gradations) in FIG. 9, when the initial condition is 255 gradations, the luminance is 100 cd / m ² and the half-life is 1000H. Further, it is assumed that the seizure visual recognition limit width is 10 gradations.

A case where the γ value of the γ characteristic is 1.0 will be described. The luminance difference corresponding to the burn-in visual recognition limit width (10 gradations) is about 4 {= 100 × (10/255)} cd / m ² . When aging is performed using the simple inverted image of FIG. 6C, the luminance difference is the largest between the area A22 with the maximum gradation 97 and the area A11 with the minimum gradation 0. The brightness of 97 gradation is about 24.7 {= 100 × (97/255)}, and the brightness of 0 gradation is 0.

Therefore, the half-life when the luminance is 24.7 (97 gradations) is (100 / 24.7) ^1.4 × 1000 = 7083.

  Based on this result and the curve S (255 gradations) in FIG. 9, as shown in FIG. 9, the deterioration characteristic curve S (97 gradations) in the case of 97 gradations and the case of 0 gradations are shown. A deterioration characteristic curve S (0 gradation) is created.

Then, based on the deterioration characteristic curve S (97) and the deterioration characteristic curve S (0), the time when the difference between the deterioration rates is 4 cd / m ² is defined as the aging time.

  When the curve S (255) is expressed in advance, the luminance difference corresponding to the burn-in visual recognition limit width (10 gradations) and the lifetime when the luminance is 24.7 (97 gradations) Based on this, an optimization time can be derived.

It is a graph which shows the deterioration characteristic SL of the organic EL element at the time of continuing displaying a low-intensity image, such as a background, and the deterioration characteristic SH of the organic EL element at the time of continuing displaying a high-intensity image, such as a character. . It is a schematic diagram which shows that a character part is visually recognized as a burn-in image. It is a schematic diagram which shows an icon image, a simple inversion video, a low level inversion video, and a low level and gain adjustment inversion image. It is a graph which shows the deterioration rate characteristic of the organic electroluminescent panel in which the aging using the reverse image | video was given. It is a schematic diagram which shows a 1st icon image and a 2nd icon image. Schematic showing icon composite image, simple inverted video, low level inverted video, and low level and gain adjustment inverted image when the ratio of the display frequency of the first icon and the display frequency of the second icon is 1: 1. FIG. Schematic showing icon composite image, simple inverted video, low-level inverted video, and low-level and gain-adjusted inverted image when the ratio between the display frequency of the first icon and the display frequency of the second icon is 1: 3 FIG. It is a schematic diagram for demonstrating optimization of the aging time in the case of aging using a simple inversion image | video. It is a schematic diagram for demonstrating optimization of the aging time in the case of performing aging using the low-level inverted video.

Claims (4)

In a method for extending the life of a display that is used in a display device having a function of combining and displaying a fixed pattern on an input image and causing a deterioration in light emission luminance according to display luminance and display time,
A method for extending the life of a display, comprising: aging the display in a state in which a simple inverted image of a fixed pattern is displayed on the display. In a method for extending the life of a display that is used in a display device having a function of combining and displaying a fixed pattern on an input image and causing a deterioration in light emission luminance according to display luminance and display time,
A simple inverted image of a fixed pattern is generated as a first inverted image, and the image data of the first inverted image is reduced to the low luminance side so that the luminance of the lowest luminance portion of the obtained first inverted image becomes 0 A method for extending the life of a display, comprising: generating a second inverted video shifted to, and performing an aging process on the display in a state where the second inverted video is displayed on the display. In a method for extending the life of a display that is used in a display device having a function of combining and displaying a fixed pattern on an input image and causing a deterioration in light emission luminance according to display luminance and display time,
A simple inverted image of a fixed pattern is generated as a first inverted image, and the image data of the first inverted image is reduced to the low luminance side so that the luminance of the lowest luminance portion of the obtained first inverted image becomes 0 A second inversion image that is shifted to the second inversion image is generated, and the image data of the second inversion image is gain-adjusted so that the luminance value of the highest luminance portion of the second inversion image becomes the maximum luminance value. A method for extending the life of a display, comprising: generating an image and performing an aging process on the display in a state where a third inverted image is displayed on the display. When there are multiple types of fixed patterns displayed on the display, a composite image of all the fixed patterns is generated in consideration of the appearance frequency of each fixed pattern, and a simple inverted image of the obtained composite image is generated as a fixed pattern. 4. The display life extension method according to claim 1, wherein the display life is extended as a simple inverted image.

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