JP2009075563A - Display method of light emitting display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the life of a display panel by restraining image persistence of a pixel. <P>SOLUTION: A light emitting display device having a display panel in which a plurality of pixels 11 including one or more sub-pixels 11a, 11b, 11c are disposed can be controlled by combination of a first display method in which light is emitted only by pixel P(i, j) at the luminescence center and a second display method in which the luminance of the pixel P(i, j) at the luminescence center is apportioned to neighborhood pixels in the periphery. According to the spatial change, temporal change, light emission time, deterioration speed, temperature, light emission luminance and display time of image input data, a high resolution mode having a higher proportion of the first display method or a long life mode having a higher proportion of the second display method is selected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-emitting display device using an organic EL, and more particularly to a display method of a light-emitting display device characterized by a pixel structure control method.

  In a flat panel image display device (flat panel display) such as an organic EL display, when the same still image is displayed for a long time, a phenomenon called “burn-in” occurs. “Burn-in” means that only a part of the screen is deteriorated (decrease in light emission luminance) so that an image trace (afterimage) becomes visible, and is likely to appear at an edge portion of a still image.

  In addition, in an organic EL display having a plurality of subpixels having different emission wavelengths, deterioration characteristics often do not match for each color. Furthermore, since the content of the image displayed on the display is not uniform, the deterioration is likely to partially progress. In this case, since the decrease in light emission luminance is different for each color, a “color shift” that appears to be colored due to a shift in white balance occurs.

  Factors that accelerate deterioration include fixed pattern display, non-uniform light emission time for each sub-pixel, light emission time, ambient temperature, light emission brightness, and so on. It is a cause.

  As a method for suppressing the image sticking phenomenon, it is preferable to improve the light emission lifetime of the constituent material, but it is difficult to say that the image sticking phenomenon can be sufficiently suppressed only by improving the material. The following documents are disclosed as techniques for suppressing the burn-in phenomenon.

  First, a technique is disclosed in which the emission luminance of each color is controlled according to the accumulated emission time, and the deterioration progress of each color is made uniform to make the burn-in less noticeable (see Patent Document 1).

  Secondly, a technique is disclosed in which the burn-in is made inconspicuous by detecting the brightness of a pixel that has deteriorated due to high-luminance emission and matching the brightness of other pixels to the brightness of the deteriorated pixel (see Patent Document 2).

JP 2000-356981 A JP 2001-175221 A

  However, the technique described in Patent Document 1 simply reduces the brightness of the entire screen according to the display time length, and the occurrence of the “burn-in” phenomenon cannot be essentially avoided. The technique described in Patent Document 2 is effective in suppressing color misregistration because the luminance of other pixels is matched with the luminance of pixels deteriorated by high luminance light emission, but the luminance of pixels is deteriorated. There is no effect to suppress itself. In addition, it is necessary to add a sensor to detect the luminance, resulting in an increase in cost and a decrease in resolution.

  In the organic EL display, when the same still image is displayed for a long time, only a part of the screen deteriorates and a burn-in phenomenon occurs. In addition, when a plurality of sub-pixels having different emission wavelengths are used, the color shift often occurs because the deterioration characteristics do not match for each color.

  The present invention has been proposed in view of the above-described problems, and provides a light-emitting display device capable of improving the life of a display panel by suppressing pixel burn-in.

The light-emitting display device of the present invention has the following features in order to achieve the above-described object. That is, the light-emitting display device of the present invention is a light-emitting display device having a display panel in which a plurality of pixels composed of one or more sub-pixels are arranged, and the vertical coordinate is i and the horizontal coordinate is j. Then, the image input data D ^a (i, j) is displayed for the sub-pixel Sp ^a (i, j) having the display color a constituting the pixel P (i, j) at the position (i, j). In this case, there are two display methods. In the first display method, the image input data D ^a (i, j) is displayed only by the sub-pixel Sp ^a (i, j). In the second display method, the display color a included in the neighboring pixel group P (i ′, j ′) arranged around the pixel P (i, j) is displayed for the image input data D ^a (i, j). This is performed by a neighboring sub-pixel group Sp ^a (i ′, j ′) consisting of a group of sub-pixels having The light emitting device of the present invention is characterized in that display control is performed by combining the first display method and the second display method, and that the combination ratio can be changed and controlled.

  In the light emitting display device of the present invention, by switching between the high resolution mode in which the ratio of the first display method is high and the long life mode in which the ratio of the second display method is high, image burn-in can be suppressed. The lifetime can be improved.

  Hereinafter, preferred embodiments of a light emitting display device of the present invention will be described with reference to the drawings.

The light emitting display device according to the embodiment of the present invention includes a display panel in which a plurality of pixels each including one or more subpixels are arranged. Here, the vertical coordinate is i and the horizontal coordinate is j. Then, the image input data D ^a (i, j) is displayed for the sub-pixel Sp ^a (i, j) having the display color a constituting the pixel P (i, j) at the position (i, j). In this case, there are two display methods. In the first display method, the image input data D ^a (i, j) is displayed only by the sub-pixel Sp ^a (i, j). In the second display method, the display color a included in the neighboring pixel group P (i ′, j ′) arranged around the pixel P (i, j) is displayed for the image input data D ^a (i, j). This is performed by a neighboring sub-pixel group Sp ^a (i ′, j ′) consisting of a group of sub-pixels having In the light emitting device of the present invention, display control is performed by combining the first display method and the second display method, and the combination ratio can be changed and controlled. Further, the combination ratio of the first display method and the second display method in the display panel can be controlled to be different for each image input data D ^a (i, j).

<First Embodiment>
1 to 15 are schematic views showing a pixel structure in the light emitting display device according to the first embodiment of the present invention.

The light-emitting display device shown in FIGS. 1 to 9 shows 3 × 3 pixels 11, and R, G, and B subpixels 11 a, 11 b, and 11 c are arranged for each pixel. An image for a sub-pixel Sp ^a (i, j) having a display color a constituting a pixel P (i, j) at a position (i, j), where i is a vertical coordinate and j is a horizontal coordinate. The input data D ^a (i, j) is displayed.

Here, the sub-pixel Sp ^a (i, j) refers to, for example, each of R, G, and B pixels that form the pixel P (i, j). The neighboring pixel group P (i ′, j ′) is, for example, neighboring pixels P (i−1, j), (i + 1, j), (i, j−1) surrounding the pixel P (i, j). ), (I, j + 1). Further, the neighboring sub-pixel group Sp ^a (i ′, j ′) is a neighboring pixel P (i−1, j), (i + 1, j), ( i, j-1) and R, G, and B pixels of (i, j + 1).

FIG. 1 shows a high-resolution display mode in which image input data D ^a (i, j) is displayed using only the first display method. In the display mode shown in FIG. 1, the sub-pixel Sp ^a (i, j) that is the emission center emits light with 100% luminance, and only the sub-pixel Sp ^a (i, j) that is the emission center emits light. Therefore, a clear image with a clear outline can be projected. However, current density is concentrated on one pixel, and there is a possibility that burn-in due to deterioration occurs.

Here, the emission luminance L ^a subpixel ^{Sp a (i, j) (} i, j), the maximum emission luminance L ^a _MAX (i, j), the gradation ^{ω a (i, j) {} 0 ≦ When ω ^a (i, j) ≦ 1}, the light emission luminance L ^a (i, j) in the case of displaying only by the first display method can be expressed by Expression (1).

FIG. 5 shows a long-life display mode in which the image input data D ^a (i, j) is displayed using only the second display method. In the display mode shown in FIG. 5, the sub-pixel P (i, j), which is the emission center, does not emit light, and adjacent neighboring pixels P (i-1, j), (i + 1, j), (i, j -1) and (i, j + 1) each emit light with a luminance of 25%.

  The current density applied to the pixel P (i, j), which is the emission center, is applied to adjacent neighboring pixels P (i−1, j), (i + 1, j), (i, j−1), and (i, j + 1). Since the pixels are evenly distributed, deterioration of the pixels P (i, j) can be reduced. Further, since the emission luminance is flattened to neighboring pixels P (i−1, j), (i + 1, j), (i, j−1), and (i, j + 1) adjacent to each other, the display mode shown in FIG. Then, the boundary of the contour line becomes smooth, and it becomes difficult to recognize a change in luminance deterioration. That is, the burn-in of the display panel can be suppressed by the synergistic effect of reducing the deterioration and smoothing the boundary between the contour lines.

FIG. 3 shows an intermediate mode between the high resolution mode and the long life mode in which the image input data D ^a (i, j) is displayed with the combination ratio of the first display method and the second display method set to 50%, respectively. It is. In the display mode shown in FIG. 3, the pixel P (i, j) that is the emission center emits light with a luminance of 50%, and the adjacent pixels P (i−1, j), (i + 1, j), (i , J−1) and (i, j + 1) emit light with a luminance of 12.5%.

  In the display mode shown in FIG. 3, the light emission luminance of the pixel P (i, j) is reduced to 50%, and the reduced luminance is equally distributed to adjacent neighboring pixels. For this reason, image sticking is suppressed as compared with the high resolution mode, but the sharpness of the image is slightly deteriorated.

Further, the combination ratio of the first display method and the second display method in the intermediate mode is not limited to the ratio shown in FIG. 3, and the ratio can be changed according to the application. 2 and 4 show display methods in which the image input data D ^a (i, j) is combined with the first display method and the second display method, and the ratio of the first display method is 80%. And an intermediate mode set to 20%.

  As the ratio of the first display method is higher, a clear image with a sharp outline can be displayed. However, a large current density is applied to the pixel P (i, j) that is the emission center, and burn-in is likely to occur. In addition, in a low-resolution display panel, there is a possibility that an adverse effect such as a jagged line becomes jagged. On the contrary, the lower the ratio of the first display method, the smoother the boundary of the contour line and the longer life display with little deterioration, but the image becomes totally blurred. However, in the case of a low-resolution display panel, there is also an effect that the contour becomes smooth and the resolution is enhanced. When combining and displaying the 1st display method and the 2nd display method, it is necessary to satisfy the following formulas (2) and (3). Here, α is the luminance distribution rate of the pixel P (i, j) and neighboring pixels.

  Further, the pixels for distributing the light emission luminance by the second display method are not limited to the pixels P (i−1, j), (i + 1, j), (i, j−1), and (i, j + 1). Absent. For example, as shown in FIG. 6, pixels P (i−1, j−1), (i + 1, j−1), (i−1, j + 1), which are positioned obliquely with respect to the pixel P (i, j), The luminance may be distributed to (i + 1, j + 1). Moreover, if the said Formula (2) and Formula (3) are satisfy | filled, there will be no restriction | limiting in the position of the allocated pixel, a number, and a ratio. For example, as shown in FIGS. 7 and 8, the total number of pixels to which the luminance is distributed by the second display method may be any number, and as shown in FIG. 9, the ratio of the luminance to be distributed by the second display method is different for each pixel. May be.

  Further, the pixels for distributing the light emission luminance in the second display method are not limited to pixels arranged in 3 × 3, and may be applied to pixels in a 5 × 5 array as shown in FIG. You may apply to the pixel of a delta arrangement | sequence as shown in FIG.

  When performing display by combining the first display method and the second display method, there may be a pixel that needs to emit light with a luminance of 100% or more. For example, FIG. 12 shows a 3 × 4 pixel, and the pixel located at the position (i, j) and the pixel located at the position (i, j + 1) emit light with 100% luminance. Here, when 40% of the second display method is applied only to the pixel at the position (i, j), as shown in FIG. 13, the pixels (i, j−1), (i−1, j), ( i + 1, j) emits light with a luminance of 10%, and the pixel (i, j + 1) emits light with a luminance of 110%. However, since the pixel cannot emit light with a luminance of 100% or more, it is necessary to correct the light emission luminance. As one means of luminance correction, there is a method of causing all pixels exceeding 100% to emit light with 100% luminance, as shown in FIG. When this method is used, a pixel whose luminance is reduced to 100% by correction is displayed at a lower luminance than usual. In particular, when the ratio of the second display method is large, there is a demerit that the decrease in luminance is also large.

  As another method of correcting the luminance, there is a method of distributing the luminance of the excess pixel exceeding 100% to the surrounding pixels. For example, as shown in FIG. 13, the second display method is applied only to the pixel at the position (i, j) on the pixel at the position (i, j) and (i, j + 1) emitting light with 100% luminance. Assume that 40% is applied. In this case, the pixels (i, j−1), (i−1, j), (i + 1, j) emit light with a luminance of 10%, and the pixels (i, j + 1) emit light with a luminance of 110%. Become. Here, since the luminance of the pixel (i, j + 1) exceeds 100%, correction for distributing the excess luminance of 10% to surrounding pixels is performed. As shown in FIG. 15, 10% of the excess luminance of the pixel (i, j + 1) is distributed to surrounding pixels by 2.5%. In this case, the pixel (i, j + 1) is 100%, the pixels (i-1, j + 1), (i, j + 2), (i + 1, j + 1) are 2.5%, and the pixel (i, j) is 62.5%. Emits light with a brightness of. When this method is used, an image can be clearly displayed and the luminance is reduced less than the correction method in which all pixels exceeding 100% are displayed with a luminance of 100%.

  As another method for correcting the luminance, there is a method of emitting light at a lower luminance in advance. This method is a method in which the maximum luminance of the display panel is set to be low in advance so that pixels that emit light with a luminance higher than 100% do not exist even when luminance distribution is performed. For example, as illustrated in FIG. 13, when a pixel (i, j + 1) that emits light with 110% luminance appears due to luminance distribution, it is necessary to correct the pixel (i, j + 1) so as to have a luminance of 100%. is there. That is, by setting the original luminance to about 90%, it is possible to prevent the luminance from exceeding 100% even if pixel distribution is performed. Although this method makes it possible to use the display method of the present invention, there is a problem that the luminance of the display panel itself decreases.

  According to the present invention, the high resolution mode, the long life mode, and the intermediate mode are selectively used depending on the application and environment, thereby reducing pixel burn-in and improving the display panel life.

For example, the second display method is used in accordance with an increase in spatial change of the image input data D ^a (i, j), ^a decrease in time change, and an increase in the light emission time of the image input data D ^a (i, j) in each pixel. It is preferable to increase the ratio. Each sub-pixel preferably increases the combination ratio of the second display method as the deterioration rate increases, and increases the combination ratio of the first display method as the deterioration rate decreases. . In addition, it is preferable to increase the combination ratio of the second display method in accordance with an increase in temperature, an increase in maximum light emission luminance, and an increase in display time.

That is, the larger the spatial change of the image input data D ^a (i, j), the larger the ratio of the second display method in the corresponding subpixel Sp ^a (i, j). In addition, the smaller the time change of the image input data D ^a (i, j), the larger the ratio of the second display method in the corresponding subpixel Sp ^a (i, j). In addition, the ratio of the second display method is increased as the image input data D ^a (i, j) has a longer emission time. Further, when there are two or more sub-pixels constituting each pixel, the combination ratio of the second display method is increased as the sub-pixel deterioration rate is faster than other sub-pixel deterioration rates, and the sub-pixel deterioration rate is increased. Is slower than the deterioration rate of the other subpixels, the combination ratio of the first display method is increased. In addition, regarding the combination ratio of the first display method and the second display method in at least one sub-pixel, the combination ratio of the second display method is increased as the temperature increases. In addition, regarding the combination ratio of the first display method and the second display method in at least one sub-pixel, the combination ratio of the second display method is increased as the maximum light emission luminance increases. In addition, regarding the combination ratio between the first display method and the second display method in at least one sub-pixel, the combination ratio of the second display method is increased as the display time increases. The ratio of the combination ratio of the first display method and the second display method in at least one subpixel is, for example, 1: 2.

  Specifically, for example, when displaying on a high-resolution display panel or displaying a fast moving video, it is preferable to use a high-resolution mode in which the emission ratio of the emission center pixel is 100%. In addition, when a fixed pattern is displayed or when a high resolution is not required, it is preferable to suppress pixel burn-in using a long life mode in which the light emission ratio of each pixel is dispersed. In addition, it is preferable to use an intermediate mode by switching to a display mode suitable for the application and environment at the standard time.

The high resolution mode, long life mode, and intermediate mode are not only switched depending on the projected image, but the display panel life can be improved by switching the display mode according to the amount of accumulated light emission, temperature, light emission brightness, etc. it can. That is, according to the spatial change and temporal change of the image input data D ^a (i, j), the light emission time of the subpixel, the deterioration rate, the temperature, the light emission brightness, the display time, etc., the high resolution mode, long life mode, intermediate mode By switching, the life of the display panel can be improved. The integrated light emission amount is an integrated value when the light emission time is the x-axis and the light emission luminance is the y-axis.

  When the deterioration characteristic of each sub-pixel changes depending on the integrated light emission amount, the life of the display panel can be improved by increasing the ratio of the second display method in the time region in which the deterioration speed increases. For example, since the deterioration rate generally decreases as the integrated light emission amount increases, when the integrated light emission amount is short, a display mode in which the light emission ratio of the light emission center pixel is low and the light emission ratio of the neighboring pixels is high is applied. By switching to a display mode in which the light emission ratio of the light emission center pixel is high and the light emission ratio of the neighboring pixels is low as the integrated light emission amount increases, a high-definition image can be displayed for a long time. Further, in the case where the deterioration characteristics of the pixels change depending on the ambient environmental temperature, the display panel lifetime can be improved by increasing the ratio of the second display method when the environmental temperature reaches a fast deterioration rate. For example, in general, when the temperature rises, the deterioration rate of the pixel increases, so when the environmental temperature is low, a display mode in which the light emission ratio of the light emission center pixel is high and the light emission ratio of the neighboring pixels is low is applied. When the environmental temperature rises, it is preferable to switch to a display mode in which the light emission ratio of the light emission center pixel is low and the light emission ratio of the neighboring pixels is high.

  Further, in the case where the deterioration characteristic changes depending on the magnitude of the light emission luminance, the display panel life can be improved by increasing the ratio of the second display method for the pixels having the light emission luminance that has a high deterioration speed. For example, it is generally considered that when the emission luminance is high, the deterioration rate of the pixels is fast. For image input data with low emission luminance, a display mode in which the emission ratio of the emission center pixel is high and the emission ratio of the neighboring pixels is low. Apply. In addition, it is preferable to apply a display mode in which the light emission ratio of the light emission center pixel is low and the light emission ratio of the neighboring pixels is high for image input data having a high light emission luminance.

  Next, a control method for displaying the first display method and the second display method will be described. FIG. 30 is a block diagram showing a configuration of a light emitting display device according to an embodiment of the present invention. As shown in FIG. 30, the light emitting display device according to the embodiment of the present invention includes a signal input unit 1, a luminance distribution unit 2, an A / D conversion unit 3, and a display unit 4. The signal input unit 1 receives an input of a video signal, and the luminance distribution unit 2 performs a luminance distribution process on the video signal input to the signal input unit 1 and outputs it. The A / D conversion unit 3 performs A / D conversion on the signal output from the luminance distribution unit 2, and the display unit 4 displays a video based on the video signal output from the A / D conversion unit 3. Furthermore, the light emitting display device according to the embodiment of the present invention includes a heat detection unit 5 that detects the ambient temperature, a current detection unit 6 that counts the light emission luminance and the cumulative light emission time of the display unit, and a cumulative light emission time detection unit 7. And.

  The luminance distribution unit 2 is a conversion unit that adjusts the ratio between the first display method and the second display method, and can select and use the high resolution mode, the long life mode, and the intermediate mode according to the environment and application. preferable.

  The heat detector 5 is a sensor for sensing temperature, and is used to measure the temperature of the light emitting display device. When the temperature of the light-emitting display device becomes a fast deterioration rate, the ratio of the second display method can be increased to suppress burn-in.

  The current detection unit 6 is used to measure the current consumed by the display device, and can increase the ratio of the second display method to the pixel unit emitting light with high luminance and suppress burn-in. Become. In addition, the accumulated light emission time detector 7 counts the accumulated light emission time, and the second display method can be applied to a portion where pixel deterioration is severe to suppress burn-in.

<Second Embodiment>
Next, a light-emitting display device according to a second embodiment of the present invention will be described. 16 to 18 are schematic views showing a pixel structure in a light emitting display device according to the second embodiment of the present invention.

FIG. 16 shows a pixel structure in a high-resolution display mode in which the image input data D ^a (i, j) is displayed using only the first display method, and 3 × 3 pixels are shown. For each pixel 11, R, G, and B sub-pixels 11a, 11b, and 11c are arranged. An image for a sub-pixel Sp ^a (i, j) having a display color a constituting a pixel P (i, j) located at a position (i, j), where i is a vertical coordinate and j is a horizontal coordinate. Assume that the input data D ^a (i, j) is displayed.

  When the deterioration characteristics of a plurality of sub-pixels having different emission wavelengths do not match, if the R, G, and B sub-pixels included in a certain pixel are always illuminated with a constant luminance, light is emitted from a sub-pixel with a fast deterioration speed and a slow sub-pixel. Luminance changes and causes color shift. In the present embodiment, the color shift of the display panel due to deterioration can be suppressed by adjusting the combination ratio of the first display method and the second display method for each sub-pixel of the light emission center pixel and the neighboring pixels.

In the high-resolution display mode shown in FIG. 16, the subpixels Sp ^a (i, j) for each RGB included in the pixel P (i, j), which is the light emission center, emit light uniformly with a luminance of 100%. It is possible to project a clear image with a clear outline. However, when the deterioration characteristics of the respective RGB colors are different, since the sub-pixels of the three colors emit light with 100% luminance, color misregistration due to luminance deterioration occurs.

The pixel P (i, j) the emission luminance of the display color a in L ^a (i, j), the maximum emission luminance _{^{L a MAX (i, j)}} , the gradation ω ^a (i, j) When, the The light emission luminance L ^a (i, j) when displayed by only the display method 1 can be expressed by the following formulas (4), (5), and (6).

FIG. 18 shows a pixel structure in the long-life display mode in which the image input data D ^a (i, j) is used for the B sub-pixel only in the second display method. As shown in FIG. 18, the R and G sub-pixels Sp ^r (i, j) and Sp ^g (i, j) included in the pixel P (i, j) which is the emission center emit light with 100% luminance. , B subpixels Sp ^b (i, j) emit no light. Instead, subpixels Sp ^b (i−1, j) included in adjacent neighboring pixels P (i−1, j), (i + 1, j), (i, j−1), and (i, j + 1), respectively. , Sp ^b (i + 1, j), Sp ^b (i, j−1), and Sp ^b (i, j + 1) each emit light with a luminance of 25%. Since the emission luminance of only the B sub-pixel is distributed to neighboring pixels, the current density applied to the B sub-pixel is flattened and deterioration can be suppressed. This display mode is effective when the deterioration rate of the B subpixel is particularly faster than the other R and G subpixels, and suppresses color shift due to burn-in by bringing the B deterioration rate closer to the R and G deterioration rates. Effect is obtained.

FIG. 17 shows a pixel structure in the intermediate mode in which the image input data D ^a (i, j) is displayed only on the B sub-pixel at a combination ratio of the first display method and the second display method by 50%. It is. As shown in FIG. 17, the R and G sub-pixels Sp ^r (i, j) and Sp ^g (i, j) included in the pixel P (i, j) which is the emission center emit light with 100% luminance. , B sub-pixel Sp ^b (i, j) emits light with a luminance of 50%. Instead, B subpixels Sp ^b (i−1, j) included in adjacent neighboring pixels P (i−1, j), (i + 1, j), (i, j−1), (i, j + 1), respectively. j), (i + 1, j), (i, j-1), and (i, j + 1) each emit light with a luminance of 12.5%. The light emission luminance of the B subpixel Sp ^b (i, j) is reduced to 50%, and the decreased luminance is the adjacent neighboring subpixel Sp ^b (i−1, j), (i + 1, j), (i , J−1), (i, j + 1). For this reason, image sticking is suppressed as compared with the high resolution mode, but the sharpness of the image is lowered. This display mode is effective when the deterioration rate of the B subpixel is faster than the other R and G subpixels. By bringing the deterioration rate of the B subpixel closer to the R and G deterioration rates, Color shift can be suppressed.

In the case where the first display method and the second display method are combined and displayed on the sub-pixel of the display color a, the light emission luminance L ^a (i, j) is expressed by the following formula (7), formula (8), formula ( 9), formula (10), formula (11), and formula (12) must be satisfied. Here, the pixel P (i, j) the emission luminance of the display color a in L ^a (i, j), the maximum emission luminance _{^{L a MAX (i, j)}} , the gradation ω ^a (i, j), α ^a (i, j) is the luminance distribution rate of the pixel P (i, j) and neighboring pixels.

The lower the emission ratio of the sub-pixels Sp ^r (i, j), Sp ^g (i, j), Sp ^b (i, j) included in the pixel P (i, j) that is the emission center, the more the current density is dispersed. Thus, the luminance deterioration is suppressed. However, it is necessary to adjust the light emission ratio so that the white balance does not shift according to the degradation characteristics of RGB.

  The combination ratio of the first display method and the second display method in the intermediate mode is not limited to the values shown in FIG. 18, and an optimum ratio is selected according to the deterioration characteristics of the sub-pixels of each color and the surrounding environment. It is preferable to select.

  For example, when displaying a fixed pattern, it is preferable to increase the ratio of the second display method in which the light emission luminances of sub-pixels that are quickly deteriorated are dispersed. Further, when displaying an intermediate color between the display colors R, G, B and white (hereinafter referred to as an intermediate color), the influence of the color shift due to the deterioration of the sub-pixel is easily noticeable. Therefore, it is preferable to increase the ratio of the second display method when displaying intermediate colors.

  Further, the second display method is not limited to one color subpixel, and may be applied to two or more color subpixels. For example, when the deterioration rate is fast in the order of display colors R <G <B, B is the second display method, G is the intermediate mode between the first display method and the second display method, and R is the first display method. By applying to the above, it is possible to suppress color misregistration by matching the deterioration rates of the respective colors.

  The combination ratio of the first display method and the second display method is not changed only by the projected image, but by changing the display mode according to the integrated light emission amount, temperature, light emission luminance, etc., the life of the display panel Can be improved.

  When the deterioration characteristic of each sub-pixel changes depending on the integrated light emission amount, the color misregistration can be suppressed by increasing the ratio of the second display method in the time region in which the deterioration speed increases. For example, when the integrated light emission amount is small, the deterioration rate of B is faster than other colors, and when the integrated light emission amount is large, the deterioration rate of R is faster than other colors. Therefore, in order to suppress the color shift of the element, a display mode in which the ratio of the second display method is high in the B subpixel is applied when the integrated light emission amount is small. Then, as the integrated light emission amount increases, the ratio of the second display method in the R sub-pixel is increased, thereby suppressing color shift due to luminance deterioration.

  In addition, when the deterioration characteristics of each sub-pixel change depending on the surrounding environmental temperature, the ratio of the second display method is increased to the sub-pixel having a high deterioration speed depending on the environmental temperature, thereby suppressing color shift due to luminance deterioration. be able to. For example, it is assumed that the deterioration rate of R is faster than other colors in a high temperature environment, and the deterioration rate of B is faster than other colors in a low temperature environment. In this case, a display mode in which the ratio of the second display method is high in the R subpixel is used in the high temperature environment, and a display mode in which the ratio of the second display method is high in the B subpixel in the low temperature environment. Thus, it is possible to suppress color misregistration due to luminance degradation.

  In addition, when the deterioration characteristics of each sub-pixel change depending on the magnitude of the light emission luminance, the ratio of the second display method is increased to the sub-pixel whose deterioration speed has been increased depending on the light emission luminance, thereby reducing the luminance deterioration. It is possible to suppress color misregistration due to. For example, a case is assumed in which the deterioration rate of R is high in high luminance light emission and the deterioration rate of B is high in low luminance light emission. In this case, a display mode in which the ratio of the second display method is high in the R sub-pixel is used in the pixel that emits high luminance, and a display in which the ratio of the second display method is high in the B sub-pixel in the low luminance emission By using the mode, color misregistration due to luminance deterioration can be suppressed.

  The light-emitting display device of the present invention suppresses color misregistration caused by deterioration characteristics of each color of RGB by applying a high resolution mode, a long life mode, and an intermediate mode for each subpixel. For example, when the deterioration rate of B is significantly faster than RG, the long life mode is applied only to the B sub-pixel, and RG uses the normal high resolution mode to realize a long life display panel without color misregistration. Can do.

<Specific examples applied to actual devices>
Next, a specific example in which the light-emitting display device according to the embodiment of the present invention is applied to an actual element will be described. 19 to 22 are luminance deterioration graphs when the light-emitting display device according to the embodiment of the present invention is applied to an actual element.

  FIG. 19 is an explanatory diagram showing normalized deterioration time data for each color when each of the R, G, and B sub-pixels is turned on to display white. As shown in FIG. 19, when it is assumed that burn-in occurs when the luminance difference between adjacent pixels exceeds 10%, burn-in is recognized in 45 hours for R, 28 hours for G, and 5 hours for B. . If all the sub-pixels are lit only by the first display method, the B sub-pixel burns in 5 hours and the G sub-pixel burns in 28 hours, resulting in a color shift in the display panel. End up. In this case, the lifetime of the display panel is 5 hours when burn-in is recognized in the B subpixel.

  Therefore, a display mode in which the first display method and the second display method are combined is used, and adjustment is performed so that the deterioration rates of the sub-pixels coincide with each other.

In the calculation used for this adjustment, a model that assumes that element destruction due to current proceeds to a current value or more (1.5 times the current value) is applied as a deterioration model of the organic EL. Expression 13 below is an expression representing an empirical model that element degradation depends on the current density to the power of 1.5. Here, τ ₁ and τ ₂ are degradation times, I ₁ and I ₂ are current densities, and L ₁ and L ₂ are emission luminances. Although it is assumed that the current density and the light emission luminance are approximately proportional, it is originally desirable to derive the current density from the IL characteristic.

FIG. 23 shows a pixel structure when the light-emitting display device according to the embodiment of the present invention is applied to an actual element. In the example shown in FIG. 23, the R subpixel Sp ^r (i, j) included in the pixel P (i, j) that is the emission center is caused to emit light by the first display method. The G subpixel Sp ^g (i, j) displays the first display method at a ratio of 70% and the second display method at a ratio of 30%. The B subpixel Sp ^b (i, j) displays the first display method at a rate of 20% and the second display method at a rate of 80%. That is, in the example shown in FIG. 23, the R subpixel Sp ^r (i, j) included in the pixel P (i, j) emits light with 100% luminance, and the G subpixel Sp ^g (i, j). Emits light with a luminance of 70%, and the B sub-pixel Sp ^b (i, j) emits light with a luminance of 20%. Further, G subpixels Sp ^g (i−1) included in adjacent neighboring pixels P (i−1, j), (i + 1, j), (i, j−1), and (i, j + 1), respectively. , J), (i + 1, j), (i, j−1), and (i, j + 1) each emit light with a luminance of 7.5%. The B subpixels Sp ^b (i−1, j), (i + 1, j), (i, j−1), and (i, j + 1) each emit light with a luminance of 20%. Since the B and G subpixels included in the pixel P (i, j), which is the emission center, disperse the emission luminance in the surrounding neighboring pixels, deterioration is suppressed. The deterioration of the B subpixel having a high dispersion ratio is further suppressed.

  FIG. 20 is a luminance deterioration graph when 30% of the second display method is incorporated into the G sub-pixel and 80% of the second display method is incorporated into the B sub-pixel. When white is displayed by such a display method, burn-in occurs in 48 hours for the R subpixel, 47 hours for the G subpixel, and 50 hours for the B subpixel. In this display mode, R, G, and B all have the same deterioration time, and display can be performed with almost no color shift due to luminance deterioration.

  FIG. 21 shows normalized deterioration time data when white is displayed in an environment of 25 ° C. and an environment of 60 ° C. Assuming that the burn-in occurs when the luminance difference between adjacent pixels exceeds 10%, burn-in is recognized in an environment of 25 ° C. for 42 hours and in an environment of 60 ° C. for 3 hours.

  Therefore, a display mode in which the first display method and the second display method are combined is used, and adjustment is performed so that the deterioration time is suppressed in an environment of 60 ° C. where the deterioration speed is high.

  FIG. 22 is a luminance deterioration graph when 80% of the second display method is incorporated in an environment of 60 ° C. This is a display mode in which the pixel at the light emission center emits light with a luminance of 20%, and the remaining 80% is distributed to surrounding neighboring pixels. When white is displayed by such a display method, burn-in is improved to 40 hours in an environment of 60 ° C. Therefore, when the ambient environmental temperature is high, the life of the display panel can be extended by applying the display mode in which the ratio of the second display method is high.

<Specific effects>
Next, detailed effects of the light emitting display device according to the embodiment of the present invention will be described.

  24 to 29 show a pixel structure for explaining detailed effects of the light emitting display device according to the embodiment of the present invention.

  FIG. 24 shows 3 × 3 pixels, where the vertical coordinate is i, the horizontal coordinate is j, and the pixel located at the position P (i, j) is 100 by the first display method. Assume that the lamp is turned on for a certain period of time. The luminance of the pixel P (i, j) before lighting for 100 hours is set to 1, and the luminance of the pixel P (i, j) after lighting for 100 hours is set to 1−α. Here, α (0 <α <1) is a luminance deterioration ratio. After lighting for 100 hours, as shown in FIG. 25, when all the pixels emit light uniformly, the luminance L (i, j) of the pixel P (i, j) is 1−α, and the neighboring neighboring pixel P ( The luminance L (i ± 1, j), (i, j ± 1) is 1 at i ± 1, j), (i, j ± 1). For this reason, if the luminance ratio at which burn-in is recognized is x, the conditions under which burn-in is not recognized when all pixels emit light can be expressed by the following equations 14 and 15. Therefore, when the display is performed only by the first display method, the deterioration due to burn-in is recognized when the luminance deterioration ratio α is higher than the burn-in recognition luminance ratio x.

  Here, consider a case where the second display method is applied and the lamp is lit for 100 hours. FIG. 26 shows a display mode in which the first display method is incorporated into the pixel P (i, j) at a rate of 1-4s and the second display method is incorporated at a rate of 4s. That is, out of the luminance applied to the pixel P (i, j), neighboring pixels P (i + 1, j), P (i-1, j), P (i, j + 1), P (i, j-1) Are turned on for 100 hours in a display mode that is distributed by s. Assume that after lighting for 100 hours in such a display mode, all pixels emit light uniformly as shown in FIG. In this case, the luminance of the pixel P (i, j) is L (i, j) = 1−α (1−4s). The luminance of the pixels P (i + 1, j), P (i-1, j), P (i, j + 1), and P (i, j-1) is L (i + 1, j), L (i-1, j), L (i, j + 1), and L (i, j-1) are 1-sα. Also, the luminances L (i + 1, j + 1), L (i + 1) of the pixels P (i + 1, j + 1), P (i + 1, j-1), P (i-1, j + 1), P (i-1, j-1). , J−1), L (i−1, j + 1), and L (i−1, j−1) are 1. For this reason, if the luminance ratio at which burn-in is recognized is x, the conditions under which burn-in is not recognized when all pixels emit light are as shown in the following formulas (16), (17), and (18).

From the above equations (16), (17), and (18), it can be seen that the ratio at which deterioration is hardly recognized is when δ ₁ = δ ₂ and s = 1/6. Therefore, it can be seen that the display method in which the deterioration is hardly recognized when light is emitted on the full screen is the display of the first display method and the second display method in a ratio of 1: 2. Further, the luminance deterioration ratio α and the luminance ratio x at which burn-in is recognized have a relationship represented by the following Expression 19, and even if the ratio of the second display method is increased, the luminance deterioration ratio α is the burn-in recognition luminance ratio x. If it is more than 6 times larger than the deterioration, the deterioration is recognized.

FIG. 28 shows a pixel structure when a vertical coordinate i is set to i and a horizontal coordinate j is lit and a pixel with j ≧ ω ₁ is lit for 100 hours. As shown in FIG. 28, the luminance of each pixel before lighting for 100 hours is set to 1, and the luminance of the pixel P (i, j) {j ≧ ω ₁ } after lighting for 100 hours is set to 1-α. Here, α (0 <α <1) is a luminance deterioration ratio. After lighting for 100 hours, as shown in FIG. 29, the area of the pixel {i ≦ ω ₂ } is caused to emit light in the display mode in which the first display method is incorporated at 1-4 s and the second display method at 4 s. It was. That is, the pixel that becomes the light emission center emits light at a rate of 1-4 s, and the current density is distributed at a rate of s to neighboring pixels that are adjacent vertically and horizontally. Here, the current density at the rate of 1 to i <omega ₂ of the pixels in the region to emit light are distributed, i = omega 1 ratio-s to ₂ pixels, adjacent to i = ω ₂ i = ω _The current density is distributed to the ₂ + 1 pixels at a rate of s. If i ≧ ω ₂ +2, no light is emitted.

  Accordingly, the luminance of each pixel is as shown in the following formula (20), formula (21), formula (22), formula (23), formula (24), and formula (25).

  Here, the conditions for recognizing burn-in between the pixel deteriorated by lighting for 100 hours and the other pixels are expressed by the following equations (26), (27), (28), and (29). Furthermore, by applying the second display method, the conditions under which the light emitting region can be seen uniformly are expressed by the following formulas (30), (31), and (32). From Expression (26), Expression (27), Expression (28), and Expression (29), since the current density distribution ratio s is 0 <s <1/4, burn-in occurs between pixels that are not degraded pixels. The recognized condition is α ≦ x. Further, the condition in which the inside of the region looks uniform due to the application of the second display method is s ≦ x.

  As described above, based on the relationship among the current density distribution rate s, the luminance deterioration ratio α, and the burn-in recognition luminance ratio x, the deterioration due to burn-in is recognized by using the second display method of the optimal current density distribution rate s. A light-emitting display device that is difficult to be formed can be manufactured.

  In the light emitting display device of the present invention, the high resolution mode in which the ratio of the first display method is high, the long life mode in which the ratio of the second display method is high, and the intermediate mode that is intermediate between them can be switched. it can.

  In the high resolution mode, a clear image with a clear outline can be displayed. However, since a load is applied to one pixel, burn-in is promoted. On the other hand, in the long-life mode, the light emission luminance of the pixels is distributed to neighboring neighboring pixel groups, so that the current density applied to the pixels is flattened and an effect of suppressing deterioration can be obtained. Further, since the light emission luminance is flattened, the boundary of the contour line becomes smooth, and the change due to luminance deterioration can be made inconspicuous.

  Therefore, by applying the long life mode in fixed pattern display or the like and switching to the high resolution mode only when a natural image or high resolution display is desired, the life of the display panel itself can be extended.

  Further, when the deterioration characteristics are different for each luminescent color, it is possible to obtain an effect of suppressing color shift by increasing the ratio of the second display method in the luminescent color whose deterioration progresses quickly.

  Other factors related to the deterioration of the luminance of the pixel include light emission time, temperature, maximum light emission luminance, and the like. When the progress of deterioration changes due to such factors, the combination ratio of the first display method and the second display method is adjusted so that the progress of deterioration is uniform for each emission color. In addition, a display panel having a longer life can be realized.

1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a first embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a second embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a second embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a pixel structure in a light emitting display device according to a second embodiment of the present invention. The luminance degradation graph at the time of applying the light emission display apparatus which concerns on embodiment of this invention to a real element. The luminance degradation graph at the time of applying the light emission display apparatus which concerns on embodiment of this invention to a real element. The luminance degradation graph at the time of applying the light emission display apparatus which concerns on embodiment of this invention to a real element. The luminance degradation graph at the time of applying the light emission display apparatus which concerns on embodiment of this invention to a real element. 1 is a schematic diagram illustrating a pixel structure when a light-emitting display device according to an embodiment of the present invention is applied to an actual element. FIG. 4 is a schematic diagram illustrating a pixel structure for explaining a detailed effect of the light emitting display device according to the embodiment of the invention. FIG. 4 is a schematic diagram illustrating a pixel structure for explaining a detailed effect of the light emitting display device according to the embodiment of the invention. FIG. 4 is a schematic diagram illustrating a pixel structure for explaining a detailed effect of the light emitting display device according to the embodiment of the invention. FIG. 4 is a schematic diagram illustrating a pixel structure for explaining a detailed effect of the light emitting display device according to the embodiment of the invention. FIG. 4 is a schematic diagram illustrating a pixel structure for explaining a detailed effect of the light emitting display device according to the embodiment of the invention. FIG. 4 is a schematic diagram illustrating a pixel structure for explaining a detailed effect of the light emitting display device according to the embodiment of the invention. 1 is a block diagram illustrating a configuration of a light emitting display device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Signal input part 2 Luminance distribution means 3 A / D conversion part 4 Display part 5 Heat | fever detection part 6 Current detection part 7 Cumulative light emission time detection part 11 Pixel 11a The 1st subpixel (R) of a pixel
11b Second sub-pixel (G) of the pixel
11c 3rd sub-pixel (B)

Claims (11)

A display method for a light emitting display device having a display panel in which a plurality of pixels each having one or more subpixels are arranged,
The vertical coordinate is i, the horizontal coordinate is j, and the subpixel Sp ^a (i, j) having the display color a constituting the pixel P (i, j) at the position (i, j). When displaying the image input data D ^a (i, j),
A first display method for displaying the image input data D ^a (i, j) only by the sub-pixel Sp ^a (i, j);
The display of the image input data D ^a (i, j) is displayed for sub-pixels having a display color a included in the neighboring pixel group P (i ′, j ′) arranged around the pixel P (i, j). A display method of a light emitting display device, comprising: a second display method performed by ^a neighboring sub-pixel group Sp ^a (i ′, j ′) composed of ^a group.   The display method of the light-emitting display device according to claim 1, wherein a combination ratio of the first display method and the second display method is changed. The light emitting display according to claim 1 or 2, wherein a combination ratio of the first display method and the second display method in the display panel is different for each image input data D ^a (i, j). Device display method. As the spatial change of the image input data D ^a (i, j) in each pixel increases, the ratio of the second display method in the corresponding subpixel Sp ^a (i, j) is increased. The display method of the light emission display apparatus of Claim 1 or 2. The ratio of the second display method in the corresponding sub-pixel Sp ^a (i, j) is increased as the time change of the image input data D ^a (i, j) in each pixel decreases. The display method of the light emission display apparatus of Claim 1 or 2. The display method of the light emitting display device according to claim 1, wherein the ratio of the second display method is increased as the light emission time of the image input data D ^a (i, j) increases. There are two or more subpixels constituting each pixel,
Each sub-pixel increases the combination ratio of the second display method as its deterioration rate increases,
The display method of the light-emitting display device according to claim 1, wherein a combination ratio of the first display methods is increased as the deterioration rate decreases.   The combination ratio of the second display method is increased as the temperature rises with respect to the combination ratio of the first display method and the second display method in at least one sub-pixel. Or the display method of the light emission display apparatus of 2.   The combination ratio of the second display method is increased as the maximum light emission luminance is increased with respect to the combination ratio of the first display method and the second display method in at least one sub-pixel. Item 3. A display method for a light-emitting display device according to Item 1 or 2.   The combination ratio of the second display method is increased with an increase in display time with respect to a combination ratio of the first display method and the second display method in at least one sub-pixel. The display method of the light emission display apparatus of 1 or 2.   The display method of the light emitting display device according to claim 1, wherein a ratio of a combination of the first display method and the second display method in at least one subpixel is 1: 2.

Images