JP5313066B2 - Electronic devices that prevent pixel burn-in - Google Patents

Description

The present invention relates to an electronic device that can prevent burn-in of pixels of a self-luminous display.

  Flat panel display (FPD) light emission methods include non-self light emitting type represented by liquid crystal display (LCD) and self light emitting type such as plasma display panel (PDP) and organic electroluminescence display (OELD). Can be broadly classified. In a self-luminous FPD, deterioration of a light emitting element forming a pixel progresses as the light emission time elapses, so that even if the same energy is supplied, so-called luminance deterioration occurs in which the luminance is lower than that at the beginning of light emission. When the luminance deterioration of the light emitting element of a certain pixel progresses more than the light emitting elements of surrounding pixels, so-called burn-in becomes possible when the same color is displayed on these pixels and the presence of the issuing element deteriorated by human eyes can be recognized The phenomenon that occurs. For example, when displaying a color display icon as a still image for a long time on a gray desktop screen, the pixel that displayed the icon is displayed when the same gray as the desktop screen is displayed in the area where the icon is displayed. A difference in brightness occurs due to image sticking between the gray and the pixels that originally displayed the desktop screen.

  The image sticking occurs due to a difference in progress of deterioration between the light emitting elements. Since gray drives each light emitting element of red, green, and blue with the same energy, three light emitting elements in one pixel are equally deteriorated. Therefore, if the entire background image such as a desktop screen is displayed in gray with uniform luminance, the burn-in problem does not occur. However, the pixels for displaying icons emit light for the same amount of time as the background image because the luminance is higher than that of the background image, or because there is a difference in the brightness of the light-emitting elements that make up red, green, and blue for color display. Even if it is done, a difference appears in the degree of luminance degradation.

  Patent Document 1 discloses a technique for displaying a plurality of color arrangement patterns that make the amount of deterioration of an element uniform on a screen in order to prevent burn-in that occurs in a self-luminous element due to a fixed pattern displayed on an organic EL display. In this document, the basic colors of R (red), G (green), and B (blue) that display the character part are displayed at the same luminance for 1/3 hour, and the background part is 1/3 of the luminance of RGB. By continuously displaying the images, the deterioration amount of the element contributing to the display of the character portion is matched with the deterioration amount contributing to the display of the background portion. The document also describes mixing R and G, G and B, and B and R when switching between RGB.

  Patent Document 2 discloses a technique for changing the display color of information statically displayed on a display panel with the passage of display time in order to prevent image sticking in a display device such as an instrument panel of an automobile. To do. Patent Document 3 describes that the luminance life half-life (life) of an organic EL element is inversely proportional to the square of the initial luminance. Non-Patent Document 1 describes that a luminance deterioration curve of an organic EL element can be fitted with an expanded exponential function.

JP 2007-286296 A JP 2008-139897 A Japanese Patent No. 3687393

Luminance degradation mechanism in organic EL elements Masahiko Ishii R & D Review of Toyota CRDL Vol.38 No.2

  The method described in Patent Document 1 makes the deterioration amount of each organic EL element uniform by a combination of luminance and display time, but in order to make the deterioration amount uniform, the color of the character portion which is a fixed pattern Changes by 1/3 hour. Therefore, it is good if the fixed pattern does not matter the color change, but it cannot be used if the color of the fixed pattern is not to be changed. For example, an icon that provides predetermined information by a pattern or pattern formed by a combination of colors is not preferable because the color changes because the wrong information is conveyed to the user or the user feels strange when the color changes. Further, when the fixed pattern is a symbol of an automobile measurement panel, the change in color is further undesirable because the time for the driver to view the symbol during driving is short.

  An organic EL light emitting element (hereinafter simply referred to as a light emitting element) employed for OELD increases in the amount of deterioration in luminance as the light emission time increases and the initial luminance increases. Pixels that display a background image and pixels that display a fixed pattern such as a computer icon, taskbar, or car measurement panel symbol emit light continuously during OELD operation, so the initial luminance of the subpixel This difference appears as the degree of deterioration of the light emitting element.

  Accordingly, an object of the present invention is to provide an electronic device capable of preventing pixel burn-in when a fixed pattern is displayed over a background image in a self-luminous display. A further object of the present invention is to provide an electronic device that can prevent pixel burn-in without changing the color of a fixed pattern.

  The electronic device according to the present invention displays a pixel and a fixed pattern for displaying the background image while keeping the color of the fixed pattern unchanged when displaying the fixed color pattern on the background image of the self-luminous display. The luminance deterioration amount of the pixel to be processed is advanced equally. Here, the fact that the color of the fixed pattern does not change means that the color recognized by the user does not change substantially, and does not mean that the display state of the pixel does not change. In the light emitting element, the longer the light emission time is, and the higher the luminance is, the more the luminance deterioration amount is. Both the pixels that display the background image and the pixels that display the fixed pattern emit light continuously while the display is operating, but the type and brightness of the light-emitting subpixels vary depending on the image being displayed, so the emission time Even if they are the same, the luminance deterioration amount changes for each sub-pixel.

  In the present invention, the background image is displayed by shortening the light emission time of the pixel displaying the fixed pattern with respect to the background image and increasing the luminance higher than that of the background image while time-dividing the pixels displaying the fixed pattern. The luminance degradation amount of the pixel to be displayed and the pixel to display the fixed pattern is made the same. If the light emission time of the pixel that displays the fixed pattern is shortened, the color of the fixed pattern has been changed until now, but in the present invention, the pixel that displays the fixed pattern is changed to the light emission pattern corresponding to the target color. The display pixel is composed of a pixel that displays a light emission pattern corresponding to an unintended color, and the light emission pattern is periodically cycled between the pixels. In the present invention, the fixed pattern is displayed by a time-division cyclic method that combines time-division light emission and cyclic light emission patterns.

  In order to make the luminance degradation amount the same as the light emitting element that continuously emits light when the light emitting time is shortened, it is not necessary to reduce the initial luminance to an extent that is inversely proportional to the degree of shortening the light emitting time. It has. In the present invention, by utilizing this property, a target color is displayed by dominating a color perceived by a human to a pixel whose light emission time is shortened. The display may be built in the electronic device or may be of a type connected to the outside. A pixel matrix is formed on the display, and a background image and a fixed pattern are simultaneously displayed on the pixel matrix.

  A plurality of pixels arranged adjacent to each other on the pixel matrix form a unit pixel group. The unit pixel group is composed of a plurality of pixels arranged continuously, and the plurality of pixels are preferably arranged in the horizontal line direction or the vertical line direction. However, the present invention is not limited to such an arrangement, and unit pixel groups may be regularly arranged in an oblique direction. The unit pixel group displays a plurality of light emission patterns. Each of the plurality of light emission patterns is composed of luminance information of sub-pixels, and the number of light emission patterns is equal to the number of pixels forming the unit pixel group. All the pixels included in the unit pixel group display the fixed pattern by sequentially switching each of the plurality of light emission patterns at a predetermined timing.

  According to such a display method, by setting the number of times each pixel displays a predetermined light emission pattern, the relative light emission time of each light emission pattern can be obtained when the unit pixel group makes a cycle of displaying a plurality of light emission patterns. Can be controlled. If two or more of the plurality of light emission patterns are set to the same luminance information so that the luminance integration effect is exhibited, the color displayed by the unit pixel group is controlled at any timing. be able to. In order to increase the degree of identity of luminance degradation, it is desirable to set the timing for switching the light emission pattern for each same elapsed time.

  In one example, the plurality of light emission patterns include a plurality of first light emission patterns that display the first color and a second light emission pattern that is different from the first light emission pattern, and the pixels that display the first light emission pattern. By making the sum of the luminances higher than the sum of the luminances of the pixels displaying the second light emission pattern, it is possible to make the human feel the first color strongly. By setting the number of first light emission patterns to 3 and the number of second light emission patterns to 1, or setting the number of first light emission patterns to 5 and the number of second light emission patterns to 1, When the pixel group is developed on the spatial axis to form a pixel matrix, the display position of the second color with respect to the first color can be set in a spatially balanced manner.

  The background image can be displayed in gray so that the three sub-pixels can be displayed with the same luminance and the luminance deterioration amount of each sub-pixel can be made the same. Alternatively, a unit pixel group is arranged in an area for displaying a background image, and the background image is displayed by time-division cyclic display in which each unit pixel group switches each of a plurality of light emission patterns different from a light emission pattern for displaying a fixed pattern. You may make it display. The plurality of light emission patterns includes a third light emission pattern for displaying the first color, a fourth light emission pattern for displaying the second color, and a fifth light emission pattern for displaying the third color. You may make it the sum total of the brightness | luminance of the pixel which displays a light emission pattern become higher than any of the sum total of the brightness | luminance which displays a 4th light emission pattern, and the brightness | luminance of the pixel which displays a 5th light emission pattern. At this time, the second light-emitting pattern may show a non-light-emitting state in which none of the sub-pixels emit light.

  According to the present invention, it is possible to provide an electronic device that can prevent pixel burn-in when a fixed pattern is displayed over a background image in a self-luminous display. Furthermore, according to the present invention, it is possible to provide an electronic apparatus capable of preventing pixel burn-in without changing the color of the fixed pattern.

It is a figure which shows an example of the fixed pattern displayed on OELD. It is a figure which shows a mode when four pixels which display a part of fixed pattern light-emit by time-sharing in time with a comparatively long period. FIG. 3 is a diagram depicting a light emission state of a sub-pixel of a unit pixel group displaying the unit pattern shown in FIG. 2. A state when the sub-pixel emits light at various relative light emission times is shown. It is a graph which shows the relationship between relative light emission time and a luminance ratio. It is a figure explaining the luminance integration effect. It is a figure explaining the display method of the fixed pattern 10 when an adjustment period is set to 4 and the number of light emission patterns is set to 2. FIG. It is a figure which shows the pixel matrix which shows a part of pixel area of the fixed pattern displayed on OELD. It is a figure which shows the mode of the screen which the pixel matrix of FIG. 8 displays. It is a figure which shows an image pattern when the unit pattern of various adjustment periods is applied to a pixel matrix. FIG. 3 is a diagram showing a pixel matrix in which a plurality of unit pixel groups shown in FIG. 2 are arranged adjacent to a vertical space axis. It is a figure which shows the example which light-emits the sub pixel which comprises the color dominant pixel of a unit pixel group by different brightness | luminance. It is a functional block diagram of the outline of the electronic device which performs the display method of the fixed pattern concerning this Embodiment.

[Relative luminance deterioration amount]
According to Non-Patent Document 1, when the organic EL light emitting element is caused to emit light, the relative luminance Lr corresponding to the ratio of the luminance decreasing with respect to the initial luminance in the normalized elapsed time is expressed by Expression (1). Here, Tn is the relative light emission time normalized with the lifetime half-life being 1. Tn is 1 for continuous light emission up to a predetermined elapsed time, and Tn is 0.75 for light emission for 75% of the time. Further, the coefficient α is 1.85 and the coefficient β is 0.58 for the target light emitting element. According to Patent Document 3, since the lifetime of the light emitting element is inversely proportional to the square of the initial luminance ratio Li, the light emitting element that emits light for the relative luminance time Tn at the initial luminance ratio Li continuously for a predetermined elapsed time. The relative luminance deterioration amount Ld with respect to the light emitting element that emits light is expressed by Expression (2). The initial luminance ratio Li is a ratio of the initial luminance of the light emitting element to the initial luminance of the light emitting element having a relative light emission time of 1.

  Here, the light emitting element A that continuously emits light at the initial luminance ratio Lio for a predetermined elapsed time (Tn = 1), and only 75% of the predetermined elapsed time (Tn = 0.75) at the initial luminance ratio Lib. It is assumed that there is a light emitting element B that emits light and a light emitting element C that emits light for an initial luminance ratio Lic for 25% of a predetermined elapsed time (Tn = 0.25). When the relative luminance decrease amount Ld of the light emitting element A and the light emitting element B is calculated based on the formula (2), the initial luminance ratio Lib of the light emitting element B is used to equalize the relative luminance deterioration amount Ld of the two at a predetermined elapsed time. Is 1.06 times the initial luminance ratio Lio of the light emitting element A. Since the light emitting element B has a relative light emission time Tn shorter than that of the light emitting element A, the relative luminance deterioration amount Ld can be matched by increasing the initial luminance ratio. The ratio of the initial luminance ratio Lib and the initial luminance ratio Lio (= 1) at this time is called the luminance ratio Li.

  Similarly, if the initial luminance ratio Lic of the light emitting element C is set to 1.37 times the initial luminance ratio Lio of the light emitting element A, the light emitting element C and the light emitting element at a predetermined elapsed time. The relative luminance deterioration amount Ld of A can be matched. Since the light emitting element C has a shorter relative light emission time than the light emitting element B, the initial luminance ratio Lic at which the relative luminance deterioration amount Ld matches that of the light emitting element A is further increased. At this time, the relative luminance deterioration amounts of the light emitting element B and the light emitting element C also coincide.

  It should be noted that although the light emitting element B has a relative light emission time Tn that is three times longer than that of the light emitting element C, the luminance ratio of the light emitting element B is set to the luminance ratio of the light emitting element C in order to match the relative luminance deterioration amount Ld. It is not necessary to lower it to 1/3 times, and in this case, it is only necessary to lower it to 77%. The present invention is based on the knowledge of the characteristics of a light emitting element that the rate of reduction in relative light emission time and the rate of increase in initial luminance are not inversely proportional when the relative luminance deterioration amount is the same.

[Brightness degradation of fixed pattern]
FIG. 1 is a diagram illustrating an example of a fixed pattern displayed on the OELD. The OELD according to the present embodiment employs a light-emitting method having a structure in which red, green, and blue light-emitting materials are independent in sub-pixels. When the pixel emits an arbitrary color, the sub-pixel emits light with an independent luminance, so that the relative luminance deterioration amount of the sub-pixel increases independently of each other. The fixed pattern 10 is displayed so as to overlap the background image 11. The fixed pattern 10 is an image expressed in color, and is formed of three regions having different colors from each other: a star region 13, a cross region 15, and a circular region 17. The fixed pattern 10 is intended for an image that causes inconvenience to the user when the hue changes with time. For example, an icon or a task bar displayed on the desktop of a personal computer can be exemplified. Or the fixed pattern 10 can illustrate the character and symbol displayed on the indicator mounted in the motor vehicle.

  The background image 11 is displayed in gray. When a pixel displays a white, black, or gray achromatic color that is generated by combining red, green, and blue with the same luminance in additive color mixing, the three sub-pixels that constitute each pixel have the same luminance and the same time. Since only the light is emitted, the relative luminance deterioration amounts of the sub-pixels displaying the background image 11 are equal to each other, and the image sticking problem does not occur between them. In the present invention, the background image 11 does not need to be limited to gray, and the background image 11 has a hue different from the fixed pattern by applying the method of displaying the fixed pattern 10 by the time-division cyclic method described below. It may be. On the other hand, since the color of the image of the fixed pattern 10 is determined by the hue, saturation, and brightness (luminance), if the color of the image of the fixed pattern 10 does not change for a long time, A difference in the relative luminance deterioration amount occurs between pixels displaying different color areas and between pixels displaying a fixed pattern and pixels displaying a background image, thereby causing a burn-in problem.

  Therefore, in order to prevent burn-in of the light emitting elements, it is necessary to control the relative light emission time and the luminance ratio so that the relative luminance deterioration amount is the same for the sub-pixels of each pixel displaying the background image 11 and the fixed pattern 10. . Since the pixel displaying the fixed pattern 10 displays a color, three sub-pixels of a certain pixel emit light with different luminance ratios. In order to adjust the light emission time and the luminance ratio of each sub-pixel so that the luminance deterioration amount becomes equal, it is necessary to change the color of the fixed pattern 10 unless an achromatic color is displayed. In this embodiment, a time-division cyclic display method described below is adopted, the relative light emission time and the luminance ratio of each sub-pixel are set so that the luminance degradation amount is the same as that of the background image 11, and a fixed pattern Do not change the color.

[Time division patrol display method]
FIG. 2 is a diagram showing a state in which four pixels displaying a part of the fixed pattern 10 emit light by a time-division cyclic method with a relatively long period. FIG. 2 shows a unit pixel group 20 in which four pixels 21, 23, 25, and 27 are arranged adjacent to each other on the space axis. The spatial axis can be a horizontal line or a vertical line of the pixel matrix. Alternatively, the spatial axis can be an oblique line of the pixel matrix. Each pixel is composed of three sub-pixels of red, green, and blue. Each of the pixels 21, 23, 25, and 27 displays with one of the light emission patterns A, B, C, and D characterized by the color of the sub-pixel that emits light and its luminance ratio.

  In an arbitrary pixel of the unit pixel group 20, the light emission patterns A, B, C, and D transition in the order of A → D → C → B on the time axis, and further repeat the transition. For example, the light emission pattern displayed by the pixel 21 transitions from A → D → C → B → A → D. In other words, the light emission patterns A, B, C, and D repeat the same transition in the unit pixel group 20 on the spatial axis. Here, a set of four light emission patterns displayed by the unit pixel group 20 arranged on the space axis at a predetermined timing on the time axis is referred to as a unit pattern. There are as many unit patterns as there are transitions of the light emission patterns on the time axis, and there are four unit patterns. Accordingly, the light emission patterns of specific pixels in each of the unit patterns 1 to 4 are shifted by one pixel in the spatial axis direction in the order of transition. The unit patterns 1 to 4 determine the color displayed by the unit pixel group 20 based on the light emission pattern included therein.

  Each of the unit patterns 1 to 4 is displayed in the unit pixel group 20 for the same time. The time during which each unit pattern is displayed is referred to as a unit light emission time. The four unit patterns are displayed in units of unit light emission time in order from unit pattern 1 and make a transition. When unit pattern 4 is reached, unit pattern 1 is returned to, and this cycle is repeated thereafter. The time for displaying all unit patterns once is called an adjustment cycle. The adjustment period represents the time until the relative luminance deterioration amount of each pixel 21, 23, 25, 27 becomes the same as that of the pixel displaying the background image 11.

  On the spatial axis, the unit pattern displayed by the unit pixel group 20 moves to the right by one pixel each time it is switched on the time axis. When the number of unit patterns and the number of pixels of the unit pixel group 20 are matched, each pixel 21, 23, 25, 27 of the unit pixel group 20 has the light emission patterns A, B, C, D during the adjustment period. Are displayed for the same unit emission time. Here, assuming that each unit pattern emits light in a unit light emission time, the adjustment period can be expressed by the number of unit patterns included therein. When the four light emission patterns included in each unit pattern are appropriately selected, the relative light emission time of the selected light emission pattern can be adjusted in units of 1/4 with respect to the adjustment period. For example, if two light emission patterns are made the same, the relative light emission time of the sub-pixel displaying it is 2/4, and if three light emission patterns are made the same, the relative light emission time of the sub-pixel emitting it is 3 /. 4 If the four light emission patterns are made the same, the amount of relative luminance deterioration cannot be made the same as that of a pixel that continuously emits light and displays a background image.

  Here, all of the light emission patterns A, B, and C emit only red and green sub-pixels, and their luminance ratio with respect to the sub-pixels of the background image 11 is set to 1.06. In the light emission pattern D, only the blue subpixel emits light, and the luminance ratio of the background image 11 to the subpixel is set to 1.37. When one adjustment cycle is completed, the sub-pixels of the pixels 21, 23, 25, and 27 emit light for 3/4 of the relative light emission time in the light emission patterns A, B, and C, and 1/4 in the light emission pattern D. It emits light for the relative light emission time of.

  The sub-pixels that display the light emission patterns A, B, and C are all red and green and the luminance ratio is 1.06, so the relative luminance deterioration amount is equal to the pixel that displays the background image. In addition, since the luminance ratio of the sub-pixel displaying the light emission pattern D is 1.37, the relative luminance deterioration amount is equal to that of the pixel displaying the background image. At this time, the sub pixels that emit light in red and green are additively mixed, whereby the pixels that display the light emission patterns A, B, and C display yellow, and the pixels that display the light emission pattern D display blue. At this time, the color perceived by humans for the unit pixel group 20 displaying each unit pattern is examined. Each unit pattern includes three pixels that display yellow and one pixel that displays blue, and the relative positions of the blue and yellow pixels are different between the unit patterns.

  When the period of time-division light emission is long to some extent, humans perceive brightness with the integrated luminance of each pixel in the spatial axis direction, so the overall screen color is also governed by the color displayed by the pixel with high integrated luminance. The integrated luminance can be calculated by the product of the number of pixels that emit light with the same light emission pattern and the luminance ratio. The integrated luminance of the pixels that display the light emission patterns A, B, and C is 1.06 × 3 = 3.18, and the integrated luminance of the pixels that display the light emission pattern D is 1.37. Since there is a difference of 32 times, humans strongly perceive yellow in any unit pattern displayed during the adjustment period.

  Since the position of the pixel that displays blue during the adjustment cycle changes four times in the unit pixel group 20, the unit pixel group 20 that displays each unit pattern displays the same color strictly. Although it cannot be said that the difference in integral luminance does not change, the color recognized by human beings hardly changes. In this specification, the colors displayed in this way are described as the same color. Pixels that emit light emission patterns A, B, and C have the significance of governing the color of the unit pattern, and such pixels are hereinafter referred to as color dominant pixels. On the other hand, a pixel that emits the light emission pattern D has the significance of making the luminance deterioration amount of each sub-pixel uniform, and the color dominant pixel displays a color different from the target color. Hereinafter, such a pixel is referred to as a deterioration adjustment pixel. The unit pixel group 20 always includes color dominant pixels and deterioration adjustment pixels. Although the color dominant pixel is always composed of a plurality of pixels, the number of deterioration adjusting pixels may be one or more as long as a significant difference can be provided in the integrated luminance.

  FIG. 3 is a diagram depicting the light emission state of the sub-pixels of the unit pixel group 20 that displays the unit pattern shown in FIG. FIG. 3 also shows a pixel 29 for displaying a background image. The length of the bar corresponding to red (R), green (G), and blue (B) corresponds to the luminance ratio.

[Number of unit patterns]
So far, the time-division cyclic display method when the number of unit patterns and the number of pixels constituting the unit pixel group is four has been described, but the present invention is also applicable to cases where the number of unit patterns is other than that. can do. Table 1 shows the result of calculating the luminance ratio Li based on the formula (2) for the pixels displayed with various relative light emission times, so that the relative luminance deterioration amount becomes equal to the pixels that emit light continuously. The adjustment period P is represented by the number of unit patterns included therein. The number Q of light emission patterns indicates the number of the same light emission patterns in which each pixel emits light in one adjustment period P. The relative light emission time of pixels displaying the same light emission pattern can be calculated by Q / P. Further, the integrated luminance of the pixels displaying the same light emission pattern can be calculated by Li × Q.

  FIG. 4 shows a state in which the sub-pixel emits light with various relative light emission times. FIG. 4 illustrates four adjustment periods of 3, 4, 5, and 6. The unit light emission time is a time during which each unit pattern is displayed. In FIG. 4, the unit light emission time is drawn so that the absolute values are equal for all the adjustment cycles. However, in order to make the relative luminance deterioration amounts of the sub-pixels the same, it is only necessary to adjust the relative light emission time in the adjustment cycle. Therefore, the absolute value of the unit light emission time may be different depending on the adjustment cycle. For example, in the case where the number of adjustment cycles is 3 and 6, if the unit light emission time is made the same, the latter adjustment cycle is doubled. Therefore, the adjustment cycle is determined first and the unit light emission time is adjusted accordingly. You may set as follows.

  FIG. 5 is a graph showing the relationship between the relative light emission time and the luminance ratio shown in Table 1. According to FIG. 5, when any two points are extracted from the graph, in order to make the relative luminance deterioration amount the same, the ratio of increasing the luminance ratio is smaller than the ratio of shortening the relative light emission time. I understand. In order for a human to feel the color strongly due to the effect of the integrated luminance in the spatial axis direction of the color displayed by the color dominant pixel, it is more effective that the ratio of the integrated luminance of the deterioration adjustment pixel and the color dominant pixel is large. If the number of deterioration adjustment pixels is 1 and the number of color dominant pixels is 5 when the adjustment cycle is 6, the difference in integrated luminance is 5.20 / 1.52, which is 3.42 times as shown in Table 1. On the other hand, if the number of deterioration adjustment pixels is 1 and the number of color dominant pixels is 2 when the adjustment period is 3, the difference in integrated luminance is 2.18 / 1.28 from Table 1. Double. Therefore, since the effect of the color dominant pixel can be enhanced by increasing the ratio between the number of color dominant pixels and the number of deterioration adjusting pixels, humans strongly feel the color displayed by the color dominant pixels.

  As long as the unit pixel group 20 displays a fixed pattern with the same unit pattern, a human will not feel a change in the color of the fixed pattern. When the unit pattern transitions, the position of the deterioration adjustment pixel changes, so that a human may feel a slight color difference. In that case, it is conceivable that the unit light emission time for displaying one unit pattern is relatively long. If an attempt is made to secure a long unit light emission time, the adjustment period becomes longer, so the time until the relative luminance deterioration amount becomes equal becomes longer, and the luminance deterioration amount becomes unbalanced during that time. Furthermore, as shown in FIG. 5, it is necessary to increase the luminance ratio of the deterioration adjustment pixels as the relative light emission time is shortened. In order to increase the luminance ratio, it is necessary to employ a light emitting element with sufficient luminance margin or to reduce the luminance of the pixel displaying the background image. The ratio of numbers must be selected taking these into account.

  The unit pattern can have the same fixed pattern color as perceived by humans due to the integration effect, while maintaining the same relative luminance degradation between the sub-pixel displaying the background image and the sub-pixel displaying the fixed pattern. As described above, the ratio of the luminance deterioration amount with respect to the relative light emission time of the light emitting element is different from the ratio of the luminance deterioration amount with respect to the luminance ratio. FIG. 6 is a diagram for explaining the luminance integration effect. In FIG. 6, it is assumed that the luminance ratio of the pixel group 31 that emits light at the relative light emission time T1 is a, and the luminance ratio of the pixel 33 that emits light at the relative light emission time T2 is b. In order for a human to feel the color emitted by the pixel group 31 more strongly than the color emitted by the pixel 33, the condition of aT1> bT2 needs to be satisfied. Therefore, (b / a) × (T2 / T1) <1 needs to be satisfied.

  This inequality means that if the ratio of the relative light emission time is smaller than the ratio of the luminance ratio, even if two types of colors are included in the unit pattern, one can feel one color. . Specifically, the case where the adjustment cycle is 4 will be described. It is assumed that the luminance ratio a of the pixel group 31 is 4/3 when the relative light emission time T1 is 3/4. Further, it is assumed that the luminance ratio b of the pixel 33 is 4 when the relative light emission time T2 is 1/4. In this case, the integrated luminance of the pixel group 31 is (4/3) × 3 = 4, the integrated luminance of the pixel 33 is 4 × 1 = 4, and both are equal (b / a) × (T2 / T1). = 1. When three sub-pixels of red, green, and blue are displayed under such conditions, the color perceived by humans becomes gray and the hue disappears, so that the color cannot be displayed. Therefore, when the light emitting element deteriorates so that the ratio of the relative light emission time and the ratio of the luminance ratio are in inverse proportion, the integration effect cannot be expected. When the adjustment cycle is set to 2, the number of unit patterns is also 2. For example, the sub-pixels of red and green are emitted by the color dominant pixel and blue is displayed by the deterioration adjustment pixel, and the relative luminance of each sub-pixel is displayed. When adjustment is performed so that the deterioration amount proceeds in the same manner, the unit pixel group displays gray, so the minimum value of the adjustment cycle needs to be 3.

[Example of number of emission patterns 2]
FIG. 7 is a diagram illustrating a display method of the fixed pattern 10 when the adjustment period is 4 and the number of light emission patterns is 2. FIG. FIG. 7 differs from FIG. 2 in that the light emission pattern C prevents any sub-pixels from emitting light, and the pixels emitting light in the light emission patterns A and B have the luminance ratio of red and green sub-pixels as shown in Table 1. It is only a point made 1.16 based on. This is because the relative light emission time of the light emission pattern D does not change at 1/4, but the light emission patterns A and B change to 2/4, so the luminance ratio is changed accordingly. Therefore, each unit pattern includes a color dominant pixel displayed by the light emission patterns A and B, a deterioration adjusting pixel displayed by the light emission pattern D, and an intermediate pixel emitting light by the light emission pattern C. An intermediate pixel is a pixel that has stopped emitting light. Even if it displays in this way, when one adjustment cycle is completed, each pixel 21, 23, 25, 27 will display each light emission pattern A, B, C, D by unit light emission time, From Table 1, the relative luminance deterioration amounts of the sub-pixels included in each of the pixels 21, 23, 25, and 27 are equal.

[Pixel matrix]
FIG. 8 is a diagram showing a pixel matrix 100 showing a part of pixels that display the fixed pattern 10 displayed on the OELD. The pixel matrix 100 is shown with 5 horizontal lines and 10 vertical lines. In the pixel matrix 100, a plurality of unit pixel groups 20 repeatedly arranged adjacent to each horizontal line displays the unit pattern described with reference to FIGS. The unit pixel groups on the even horizontal lines and the unit pixel groups on the odd horizontal lines have the same light emission pattern on the vertical lines. The unit pixel group on the even horizontal line and the unit pixel group on the odd horizontal line are out of phase by two pixels in the horizontal direction. Each pixel of the pixel matrix 100 displays four image patterns 1 to 4 on the time axis during the adjustment period. In FIG. 8, light emission patterns of 10 × 5 pixels that display the image pattern 1 are indicated by AD.

  FIG. 9 is a diagram showing a state of the screen displayed by the pixel matrix 100 of FIG. In FIG. 9, white pixels display yellow, and patterned pixels display blue. In this example, the adjustment period is 4, and the number of light emission patterns for the color dominant pixel and the number of light emission patterns for the deterioration adjustment pixel are 3 to 1. In odd horizontal lines and even horizontal lines, pixels on the same vertical line display the same color. Further, the colors displayed by the pixels on the even numbered horizontal lines and the pixels on the odd numbered horizontal lines are shifted in phase by two light emission patterns in the horizontal direction. By displaying in this way, the adjustment pixels for displaying blue are arranged evenly in a plane in the pixel matrix 100, and the color displayed by the color dominant pixels recognized by the user can be made more uniform.

[Image pattern for other adjustment cycles]
FIG. 10 is a diagram illustrating an image pattern when unit patterns having various adjustment periods are applied to the pixel matrix 100. The image pattern in FIG. 10A is composed of unit patterns including two light emission patterns that display yellow with an adjustment period of 3 and one light emission pattern that displays blue. Since two pixels for displaying the yellow light emission pattern are inserted between the pixels for displaying the blue light emission pattern, the phase of the horizontal line is sequentially shifted by one pixel. As a result, the blue pixels become diagonal stripes.

The image pattern in FIG. 10B includes four light emission patterns that display yellow with an adjustment period of 5, and one light emission pattern that displays blue. Since four pixels for displaying the yellow light emission pattern are inserted between the pixels for displaying the blue light emission pattern, the spatial density of the pixels for displaying the blue light emission pattern is partially biased. The image pattern in FIG. 10C includes five light emission patterns for displaying yellow and one light emission pattern for displaying blue with an adjustment period of 6. Since five pixels for displaying the yellow light emission pattern are inserted between the pixels for displaying the blue light emission pattern, the phase of the horizontal line is sequentially shifted by three pixels. As a result, the light emission patterns on the vertical lines match between the even horizontal lines and the odd horizontal lines, and the blue pixels are arranged in a spatially balanced manner.

[Pixel matrix with spatial axis as vertical line]
FIG. 11 is a diagram showing a pixel matrix 200 in which a plurality of unit pixel groups shown in FIG. 2 are arranged adjacent to a vertical space axis. In this case, the light emission patterns A, B, C, and D transition in order on the vertical line every time the image pattern is switched on the time axis. Also, pixels on even vertical lines and pixels on odd vertical lines emit the same light emission pattern on the same horizontal line. The phases of the light emission patterns displayed by the pixels on the odd vertical lines and the light emission patterns emitted by the pixels on the even vertical lines are shifted by two pixels in the vertical direction. Up to now, only one example of the deterioration adjustment pixel has been shown, but it is only necessary that the integrated luminance of the color dominant pixel is larger than the integrated luminance of the deterioration adjustment pixel, and therefore it is not necessary to limit the deterioration adjustment pixel to one. .

  In addition, although an example in which yellow is displayed in the color dominant pixel, the red and blue sub-pixels can emit light with the same luminance to be magenta and the deterioration adjustment pixel can be green in the color dominant pixel. In addition, the blue and green sub-pixels can emit light with the same luminance to be cyan in the color dominant pixel, and the deterioration adjustment pixel can be red. If the time-division cyclic method according to the present invention is adopted, a plurality of colors can be displayed in this way, so that the star area 13 is displayed in yellow and the cross area 15 is displayed in magenta for the fixed pattern 10 in FIG. It is also possible to display the circular area 17 in cyan. Furthermore, in each pixel constituting the color dominant pixel, the example in which the two sub pixels emit light with the same luminance has been described. However, the two sub pixels in each pixel of the color dominant pixel can also emit light with different luminance.

[Example of displaying colors with different color dominant pixels]
FIG. 12 is a diagram illustrating an example in which the sub-pixels constituting the color dominant pixel of the unit pixel group 20 emit light with different luminance. As in the example of FIG. 3, the adjustment period is set to 4, the red sub-pixel has a relative light emission time of 3/4 and a luminance ratio of 1.06, and the green sub-pixel has a relative light emission time of 2/4 and a luminance ratio. 1.16, the blue sub-pixel has a relative light emission time of 1/4 and a luminance ratio of 1.37, so that the relative luminance deterioration amount of each sub-pixel and the relative luminance deterioration amount of the pixel displaying the background image can be reduced. Can be matched. Here, as an example, in the light emission patterns A and C shown in FIG. 2, the luminance ratio of the red sub-pixel is 1.06 and the luminance ratio of the green sub-pixel is 1.16. In the light emission pattern B, the luminance ratio of the red sub-pixel is set to 1.06. In the light emission pattern D, the luminance ratio of the blue sub-pixel is set to 1.37 . Then, if the unit pixel group 20 displays each unit pattern in a time-division cyclic manner as shown in FIG. 12, the integrated luminance obtained by combining the light emission patterns A and C becomes the highest, and the overall color is controlled. The pattern B and the light emission pattern D are interspersed therein, and the unit pixel group 20 that displays the light emission patterns A, B, C, and D displays a color different from the color of FIG. 2 as a whole.

[Configuration of electronic equipment]
FIG. 13 is a schematic functional block diagram of an electronic apparatus 300 that executes the fixed pattern display method described with reference to FIGS. The electronic device 300 can be a display device including an OELD such as a portable personal computer, a mobile phone, and a display panel of an automobile. Alternatively, the electronic device 300 can be a display device that is used by connecting an OLED to an external connection terminal. The electronic device 300 includes an image data generation unit 301, a pattern / data storage unit 303, a switching event generation unit 305, an image data output unit 307, and an OELD 309.

  The image data generation unit 301 includes a processor, a main memory, a computer program, and the like. The image data generation unit 301 generates data for displaying an image other than the fixed pattern on the OELD 309 and outputs the data to the image data output unit 307. The pattern data storage unit 303 is configured by a nonvolatile memory or the like, and stores data for displaying a plurality of image patterns corresponding to the fixed pattern. The data stored in the fixed pattern includes the position on the pixel matrix and the gradation information related to the initial luminance adjusted by the luminance ratio with respect to the initial luminance of the background image.

  The switching event generation unit 305 generates a switching event that is a timing for switching an image pattern and notifies the pattern / data storage unit 303 of the switching event. The switching event generation unit 305 acquires information on the OELD operating time from the time measuring device, calculates the timing for switching the image pattern, and generates a switching event. In this embodiment, the unit light emission time can be selected as a relatively long time such as about 10 hours to several days. Since the unit light emission time does not need to be managed so strictly, the switching event generation unit 305 is a power-on timing in the case of a portable personal computer in which the electronic device operates only for an almost constant time every day. A switching event may be generated.

  The pattern data storage unit 303 switches the image pattern to be sent to the image data output unit 307 every time a switching event is received. The image data output unit 307 includes a buffer, expands the image data received from the image data generation unit 301 and the image pattern data received from the pattern / data storage unit 303 into the buffer, and displays the OELD in a display order at a predetermined timing. Output to. The OELD 309 displays the image data generated by the image data generation unit 301 and the image pattern output from the pattern / data storage unit 303. So far, OELD has been exemplified and described as a display. However, the present invention can also be applied to other self-luminous type displays such as PDP (Plasma Display Panel).

  Although the present invention has been described with the specific embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and is known so far as long as the effects of the present invention are achieved. It goes without saying that any configuration can be adopted.

DESCRIPTION OF SYMBOLS 10 ... Fixed pattern 11 ... Background image 20 ... Unit pixel group 21, 23, 25, 27 ... Pixel 100, 200 ... Pixel matrix 300 ... Electronic device

Claims (8)

An electronic device that displays a fixed color pattern on a background image of a self-luminous display,
A plurality of pixels arranged adjacent to each other on a pixel matrix constitute a unit pixel group displaying a part of the fixed pattern,
The unit pixel group is formed by including a plurality of first light emission patterns configured by luminance information of sub-pixels each emitting light and displaying a first color and a second light emission pattern different from the first light emission pattern. The unit pixel group displays a plurality of light emission patterns corresponding to the number of pixels,
The total luminance of the pixels displaying the first light emission pattern is higher than the total luminance of the pixels displaying the second light emission pattern;
All the pixels included in the unit pixel group display the background image while keeping the color of the fixed pattern from changing by sequentially switching and displaying each of the plurality of light emission patterns at a predetermined timing. An electronic device that progresses the luminance deterioration amount of the pixels displaying the fixed pattern equally . The electronic device according to claim 1 number is 1 of the second light emission pattern number 3 of the plurality of first light emission pattern. It said first emission pattern electronic device according to claim 1 number is the number of the second light emitting pattern 5 is one of. A plurality of the unit pixel groups are arranged adjacent to each other on a horizontal line of the pixel matrix in order to display the fixed pattern, and a position of a pixel displaying the second light emission pattern between the adjacent horizontal lines is predetermined. The electronic device according to claim 1 , wherein the electronic device is shifted in the horizontal direction by the number of pixels. A plurality of the unit pixel groups are arranged adjacent to each other on a vertical line of the pixel matrix in order to display the fixed pattern, and a position of a pixel that displays the second light emission pattern between the adjacent vertical lines is predetermined. The electronic device according to claim 1 , wherein the electronic device is shifted in the vertical direction by the number of pixels. The unit pixel group is arranged in a pixel matrix for displaying the background image, and the unit pixel group switches the background image by switching each of a plurality of light emission patterns different from the light emission pattern for displaying the fixed pattern at a predetermined timing. The electronic device according to claim 1 , wherein the electronic device is displayed.   The plurality of light emission patterns include a third light emission pattern for displaying a first color, a fourth light emission pattern for displaying a second color, and a fifth light emission pattern for displaying a third color. The sum of the luminances of the pixels that display the third light emission pattern is higher than both the total luminance of the pixels that display the fourth light emission pattern and the total luminance of the pixels that display the fifth light emission pattern. 1. The electronic device according to 1. The electronic device according to claim 7 , wherein the fourth light emitting pattern indicates a non-light emitting state in which none of the sub-pixels emit light.

Images