JP2007323966A - Organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an organic EL element emit light of the same emission light intensity by carrying the same current thereto. <P>SOLUTION: This organic EL display device has a display panel 20. R pixel regions 23r, G pixel regions 23g and B pixel regions 23b are two-dimensionally arranged on a surface of the display panel 20. Luminescent regions 24 are respectively formed on the R pixel regions 23r, the G pixel regions 23g and the B pixel regions 23b. Each luminescent region 24 is formed with an organic EL layer. The organic EL layer has a luminescent layer. The areas of the luminescent regions 24 of the R pixel regions 23r, the G pixel regions 23g and the B pixel regions 23b are defined according to luminous efficiency of the luminescent layer, the service life of the luminescent layer, and filter efficiency of a color filter covering the pixel regions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic EL display device in which a display surface is formed by pixels having organic EL elements.

  An organic EL display device using an organic EL element is known. On the display surface of the organic EL display device, for example, pixels that emit red, green, and blue light are two-dimensionally arranged. Each pixel is provided with an organic EL element that emits red light, an organic EL element that emits green light, and an organic EL element that emits blue light. By controlling the amount of light emitted from each pixel according to the received video signal, an image corresponding to the video signal is displayed on the display surface.

  Since organic EL elements use different materials depending on the light emission color, the light emission efficiency differs depending on the light emission color. In order to emit light having the same luminance, it was necessary to pass a larger current in some organic EL elements than in other organic EL elements. As a result, it has been a problem that the organic EL element that allows a large current to flow deteriorates more rapidly than other organic EL elements.

In order to solve this problem, it has been proposed to change the area of the opening of the pixel in accordance with the light emission efficiency (see Patent Document 1). However, only by changing the area of the opening in accordance with the light emission efficiency, it has been impossible to cause light of the same luminance to be emitted by flowing a current of the same magnitude.
JP 2001-290441 A

  Accordingly, an object of the present invention is to provide an organic EL display device that emits light having the same luminance by flowing a current having the same magnitude regardless of the type of light to be emitted.

  The first organic EL display device of the present invention has a first and second pixels having first and second organic EL elements that emit light of first and second color components, respectively, two-dimensionally on a display surface. The light emitting area that is the area of the light emitting portion that emits the light of the first and second color components in the first and second pixels is the element life that is the life of the first and second organic EL elements. It is characterized by being determined accordingly.

  The light emitting area is preferably determined so as to be inversely proportional to the element lifetime.

  The second organic EL display device of the present invention includes first and second organic EL elements that emit light of the first and second color components and a partial band of light of the first and second color components, respectively. First and second pixels having first and second color filters that transmit light in a two-dimensional manner on the display surface, and the first and second color components of the first and second pixels The first and second organic EL elements emit radiances of light of the first and second color components that have a light emitting area that is an area of a light emitting portion that emits light and passes through the first and second color filters. It is determined according to the filter efficiency calculated by dividing by the radiance of the light of the first and second color components.

  The light emitting area is preferably determined so as to be inversely proportional to the filter efficiency. Furthermore, it is preferable that the light emission area is determined according to the light emission efficiency of the first and second organic EL elements. Furthermore, it is preferable that the light emission area is determined to be inversely proportional to the light emission efficiency.

  A third organic EL display device of the present invention is a color pixel repeating unit in which first and second pixels having first and second organic EL elements that emit light of first and second color components are arranged. Is provided, and the number of first and second pixels arranged in a color pixel repeating unit is determined according to predetermined characteristics of the first and second organic EL elements. .

  In addition, it is preferable that a predetermined characteristic is the element lifetime which is the luminous efficiency of a 1st, 2nd organic EL element, or the lifetime of a 1st, 2nd organic EL element. Alternatively, the first and second pixels have first and second color filters that transmit light in a part of the band of the first and second color components, and the predetermined characteristics are the first and second colors. By dividing the radiance of light of the first and second color components transmitted by the two color filters by the radiance of light of the first and second color components emitted by the first and second organic EL elements. The calculated filter efficiency is preferred.

  In addition, it is preferable to reduce the number of pixels having organic EL elements with higher luminous efficiency. Alternatively, it is preferable to reduce the number of pixels having an organic EL element having a longer element lifetime. Alternatively, it is preferable to reduce the number of pixels having organic EL elements with higher filter efficiency.

  According to the present invention, the light of each color component in the entire display panel can be made to have the same amount of emitted light while flowing the same amount of current through each organic EL element.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram schematically showing a configuration of an organic EL display device to which the first embodiment of the present invention is applied.

  The organic EL display device 10 includes a display panel 20, a display panel drive circuit 11, an anode line drive circuit 12, and a cathode line scanning circuit 13. In FIG. 1, the vertical direction is the vertical direction, and the horizontal direction is the horizontal direction.

  The display panel 20 is provided with anode lines 21 extending in the vertical direction and cathode lines 22 extending in the horizontal direction. A plurality of anode lines 21 are arranged in a horizontal direction. Further, the plurality of cathode lines 22 are arranged in the vertical direction. A pixel region 23 is formed at the intersection of the anode line 21 and the cathode line 22. A plurality of pixel regions 23 are arranged in a matrix on the display surface of the display panel 20.

  An organic EL element (not shown), which is a light emitting element capable of controlling the light emission amount, is provided in each pixel region 23. As will be described later, the organic EL element is formed by connecting one end of an organic EL layer (not shown in FIG. 1) to the anode line 21 and the other end to the cathode line 22. By controlling the light emission amount of the organic EL layer in each pixel region 23, a desired image is displayed on the display surface.

  The anode line 21 is connected to the anode line drive circuit 12. The cathode line 22 is connected to the cathode line scanning circuit 13. The anode line drive circuit 12 is provided with a plurality of anode line switches 12sw. Each anode line switch 12sw is connected to each anode line 21. Further, the cathode ray scanning circuit 13 is provided with a plurality of cathode ray switches 13sw. Each cathode line switch 13sw is connected to each cathode line 22. By switching ON / OFF of each anode line switch 12sw and each cathode line switch 13sw and controlling the current flowing through each anode line 21, the amount of light emitted from each organic EL layer is controlled.

  As will be described later, the anode line drive circuit 12 controls ON / OFF switching of each anode line switch 12sw and the value of a current flowing through each anode line 21. Further, switching of ON / OFF of each cathode ray switch 13sw is controlled by the cathode ray scanning circuit 13. The anode line drive circuit 12 and the cathode line scanning circuit 13 are driven by the display panel drive circuit 11.

  An operation performed in the organic EL display device 10 when displaying an image will be described. The organic EL display device 10 receives video data sent from an external device or the like. The video data is sent to the display panel drive circuit 11. In the display panel drive circuit 11, the video data is converted into drive control data. Drive control data is sent to the anode line drive circuit 12 and the cathode line scanning circuit 13.

  The cathode ray scanning circuit 13 sequentially switches ON / OFF of each cathode ray switch 13sw in accordance with input drive control data. By switching ON / OFF, each cathode line 22 is scanned in the vertical direction. The cathode line 22 in the ON state can be energized. The cathode line 22 is scanned from the top to the bottom or from the bottom to the top in order to display the screen for one frame.

  The anode line drive circuit 12 switches on / off of each anode line switch 12sw in accordance with input drive control data. A current flows through the anode wire 21 in the ON state. A current flows through the organic EL layer disposed at a position where the cathode line 21 switched to be energized and the anode line 21 through which the current flows intersect.

  The value of current flowing through each anode line 21 is adjusted for each cathode line 22 to be scanned. Adjustment of the value of the current passed through each anode line 21 is controlled according to drive control data. A current corresponding to the video data is supplied to all the organic EL layers during one frame scan, whereby an image corresponding to the video data is displayed on the display panel 20.

  Next, the configuration in the thickness direction of the organic EL element will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view in the thickness direction of the organic EL element. The organic EL element 30 is configured by laminating an anode line 21, an organic EL layer 32, a cathode line 22, and a color filter 33 on a substrate 31.

  The substrate 31 is formed of a light-transmitting member such as glass or resin. The anode line 21 and the cathode line 22 are transparent electrodes, and are formed by, for example, ITO (Indium Tin Oxide), ATO (Antimony Doped Tinoxide), or the like. The color filter 33 transmits light in a specific band from the same type of color component as the light emitted from the organic EL element 30 toward the outer surface of the display panel 20.

  In the organic EL layer 32, the hole injection layer 34, the hole transport layer 35, the light emitting layer 36, the electron transport layer 37, and the electron injection layer 38 are in close contact with each other in the order from the anode line 21 side to the cathode line 22 side. Are stacked.

  Holes injected from the anode wire 21 are taken in by the hole injection layer 34. Holes injected from the anode wire 21 are effectively injected into the light emitting layer 36 by the hole transport layer 35. Electrons injected from the cathode line 22 are taken in by the electron injection layer 38. Electrons injected from the cathode line 22 are effectively injected into the light emitting layer 36 by the electron transport layer 37.

  The color component of the light to be emitted is determined for each pixel region 23, and the light emitting layer 36 is formed of a different material for each color component of the light to be emitted. The light emitting layer 36 is either a red light emitting layer that emits red light, a green light emitting layer that emits green light, or a blue light emitting layer that emits blue light.

  The holes and electrons injected into the light emitting layer 36 are recombined in the light emitting layer 36. By recombination, light corresponding to the material forming the light emitting layer 36, that is, light of red light, green light, or blue light is emitted.

  As the color filter 33, any of an R color filter that transmits red light in a predetermined band, a G color filter that transmits green light in a predetermined band, and a B color filter that transmits blue light in a predetermined band is used. The type of the color filter 33 is different for each pixel region 23, and the color filter 33 that transmits light of the same color component as the color component of the light emitted from the light emitting layer 36 is used.

  Next, the configuration of the display surface of the display panel will be described with reference to FIG. FIG. 3 is a plan view of the display panel. On the display surface of the display panel 20, an R pixel region 23r that emits red light, a G pixel region 23g that emits green light, and a B pixel region 23b that emits blue light are arranged according to a stripe method.

  In each pixel region 23, a light emitting region 24, which is a region where an organic EL element is formed, is provided. Each light is emitted from the light emitting region 24. The area of the light emitting region 24 is adjusted to be different depending on the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b. The area of the light emitting region 24 is adjusted by changing the area of the light emitting layer 36 in the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b.

  The area of the light emitting region 24 is determined according to the light emitting efficiency of the light emitting layer 36 in each pixel region 23, the light emitting lifetime of the light emitting layer 36, and the filter efficiency of the color filter 33 for the light emitted from the light emitting layer 36. As the luminous efficiency increases, the area of the light emitting region 24 is reduced. Further, the light emitting region 24 is formed so that the area thereof becomes smaller as the light emitting lifetime becomes longer. Further, the area of the light emitting region 24 is reduced as the filter efficiency of the color filter 33 with respect to the light emitted from the light emitting layer 36 increases.

  The luminous efficiency is the amount of light emitted from the organic EL layer 32 with respect to the current supplied to the organic EL layer 32. Further, the light emission lifetime may be any index as long as it is an index indicating the deterioration state of the light emitting layer 36. In the present embodiment, an index obtained by dividing the light emission amount of the light emitting layer 36 after a predetermined time by the light emission amount of the light emitting layer 36 in the initial state is used. The filter efficiency is an index obtained by dividing the amount of light emitted from the color filter 33 in the color filter 33 integrated with the organic EL element 30 by the amount of light incident from the light emitting layer 36 and incident on the color filter 33. is there.

  The light emission efficiency of the light emitting layer 36, the light emission lifetime of the light emitting layer 36, and the filter efficiency of the color filter 33 with respect to the light emitted from the light emitting layer 36 are constant in the same type of pixel region 23, and are different depending on the pixel regions 23 of different types. Is different. Therefore, the area of the light emitting region 24 in each pixel region 23 is the same, and the areas of the light emitting regions 24 in the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b are different.

  The areas of the light emitting regions 24 of the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b are determined to be proportional to the reciprocal of the product of the light emission efficiency, the light emission lifetime, and the filter efficiency in each pixel region 23.

  For example, in the present embodiment, the light emission efficiencies in the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b are 15, 30, 5 (cd / A), respectively, and the light emission lifetimes are 0.3, 0.6,. 9. The filter efficiencies are 0.8, 0.3 and 0.6, respectively. The product of the light emission efficiency, light emission lifetime, and filter efficiency of the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b is 15 × 0.3 × 0.8, 30 × 0.6 × 0.3, and 5 × 0. .9x0.6.

  Therefore, the area of the light emitting region 24 in the R pixel region 23r, the G pixel region 23g, and the B pixel region 23b is 1 / (15 × 0.3 × 0.8): 1 / (30 × 0.6 × 0.3). ): 1 / (5 × 0.9 × 0.6) = 1.5: 1: 2.

  According to the organic EL display device 10 of the present embodiment as described above, it is possible to emit the same amount of emitted light to each pixel region 23 with higher accuracy while flowing the same amount of current. This is because the light emission area is determined in consideration of not only the light emission efficiency but also factors that affect the amount of light emitted from the entire pixel region 23.

  Next, a second embodiment of the present invention will be described. In the present embodiment, the configuration of the display surface of the display panel 200 is different from that of the first embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment. In addition, the same code | symbol is attached | subjected to the site | part which has the same function as 1st Embodiment.

  The configuration of the display surface of the display panel 200 in the organic EL display device to which the second embodiment is applied will be described with reference to FIG. FIG. 4 is a plan view of the display panel of the second embodiment. On the display surface of the display panel 200, an R pixel region 230r that emits red light, a G pixel region 230g that emits green light, and a B pixel region 230b that emits blue light are arranged. Unlike the first embodiment, the areas of the light emitting regions (not shown in FIG. 4) in the R pixel region 230r, the G pixel region 230g, and the B pixel region 230b are the same.

  In addition, the light emission efficiency of the light emitting layer 36 in each pixel region 230, the light emission lifetime of the light emitting layer 36, and the filter efficiency of the color filter 33 with respect to the light emitted from the light emitting layer 36 are the same as those in the first embodiment.

  A single color pixel repeating unit 25 is formed by the three R pixel regions 230r, the two G pixel regions 230g, and the four B pixel regions 230b. An R pixel region 230r, a G pixel region 230g, and a B pixel region 230b are arranged on the display surface so that the color pixel repeating unit 25 is repeated in a matrix.

  In the single color pixel repeating unit 25, the area ratios of all the light emitting regions of the R pixel region 230r, all of the light emitting regions of the G pixel region 230g, and all of the light emitting regions of the B pixel region 230b are 3: 2: 4 (= 1. 5: 1: 2).

  As in the first embodiment, any one of the R pixel region 230r, the G pixel region 230g, and the B pixel region 230b is formed at the intersection of the anode line 21 and the cathode line 22. Therefore, it is possible to control the light emission amount of the organic EL layer for each pixel region.

  Even with the organic EL display device of the present embodiment having the above-described configuration, the amount of light emitted from the entire R pixel region 230r in the color pixel repeating unit 25 and the light emitted from the entire G pixel region 230g while flowing the same current. The amount of light and the amount of light emitted from the entire B pixel region 230b can be made the same.

  Note that, unlike the first embodiment, since the area of the light emitting region in all the pixel regions 230 is the same, manufacturing is easier compared to a configuration in which the area of the light emitting region is changed for each pixel region.

  In the first and second embodiments, the color components of light emitted to the pixel areas 23 and 230 are three colors of red, green, and blue. In addition, light of other color components may be emitted.

  Further, the ratio of the area of the light emitting region in the first embodiment or the ratio of the number of pixel regions included in a single color pixel repeating unit in the second embodiment is the light emission efficiency, the element lifetime, and the filter efficiency, respectively. However, it is not necessary to make it in inverse proportion. The area of the light emitting region in the first embodiment or the number of pixel regions included in a single color pixel repeating unit in the second embodiment is such that the larger the light emitting efficiency, the longer the device life, or the filter efficiency. Any configuration may be used as long as it increases.

  In addition, when not making it in inverse proportion, what is necessary is just to adjust the electric current value sent through the organic EL element 30 for every color component. Compared to the conventional case where the areas of all the light emitting regions are the same, it is possible to emit light having the same luminance with the same current value.

  In the first embodiment, the area of the light emitting region 24 in each pixel region 23 is determined based on the light emitting efficiency, the element lifetime, and the filter efficiency, but may be determined based on at least one of them.

  In the second embodiment, the number of R pixel regions 230r, G pixel regions 230g, and B pixel regions 230b that form a single color pixel repeating unit 25 is determined based on light emission efficiency, element lifetime, and filter efficiency. However, it may be determined based on at least one of them.

  In the second embodiment, the light emission amount of the organic EL layer in each of the R pixel region 230r, the G pixel region 230g, and the B pixel region 230b is controlled, but at the intersection of the anode line 21 and the cathode line 22 The color pixel repeating unit 25 may be formed to control the light emission amount of all the organic EL layers included in the color pixel repeating unit 25.

  According to such a structure, since it becomes a simpler structure than 2nd Embodiment, manufacture becomes easy. Moreover, although the light emitted by such a configuration is white light, it is possible to display an image that does not require color display. Even with such a configuration, it is possible to display a color image if the color pixel repeating unit 25 is covered with different color filters.

1 is a block diagram schematically showing a configuration of an organic EL display device to which a first embodiment of the present invention is applied. The typical sectional view of the thickness direction of an organic EL element is shown. It is a top view of the display panel of a 1st embodiment. It is a top view of the display panel of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Organic EL display device 20, 200 Display panel 23 Pixel area 23r, 230r R pixel area 23g, 230g G pixel area 23b, 230b B pixel area 24 Light emitting area 30 Organic EL element

Claims (15)

First and second pixels having first and second organic EL elements that respectively emit light of the first and second color components are provided in a two-dimensional form on the display surface;
The light emitting area, which is the area of the light emitting portion that emits the light of the first and second color components, in the first and second pixels corresponds to the element life that is the life of the first and second organic EL elements. An organic EL display device characterized by the above.   2. The organic EL display device according to claim 1, wherein the light emitting area is determined so as to be inversely proportional to the element lifetime. First and second organic EL elements that emit light of first and second color components, respectively, and first and second light that transmit a part of the band of light of the first and second color components. The first and second pixels having the color filter are provided two-dimensionally on the display surface,
In the first and second pixels, a light emitting area that is an area of a light emitting portion that emits light of the first and second color components is transmitted through the first and second color filters. It is determined according to the filter efficiency calculated by dividing the radiance of the light of the two color components by the radiance of the light of the first and second color components emitted from the first and second organic EL elements. An organic EL display device characterized by that.   4. The organic EL display device according to claim 3, wherein the light emitting area is determined so as to be inversely proportional to the filter efficiency.   5. The organic EL display device according to claim 3, wherein the light emitting area is determined according to an element lifetime which is a lifetime of the first and second organic EL elements.   6. The organic EL display device according to claim 5, wherein the light emitting area is determined so as to be inversely proportional to the element lifetime.   7. The organic EL display device according to claim 1, wherein the light emitting area is determined according to light emission efficiency of the first and second organic EL elements.   8. The organic EL display device according to claim 7, wherein the light emission area is determined so as to be inversely proportional to the light emission efficiency. A display surface in which a color pixel repeating unit in which first and second pixels having first and second organic EL elements that respectively emit light of first and second color components are arranged is repeated;
An organic EL display device, wherein the number of the first and second pixels arranged in the color pixel repeating unit is determined according to predetermined characteristics of the first and second organic EL elements.   The organic EL display device according to claim 9, wherein the predetermined characteristic is light emission efficiency of the first and second organic EL elements.   The organic EL display device according to claim 10, wherein the number of pixels having an organic EL element having a higher luminous efficiency is reduced.   10. The organic EL display device according to claim 9, wherein the predetermined characteristic is an element lifetime which is a lifetime of the first and second organic EL elements.   The organic EL display device according to claim 12, wherein the number of pixels having an organic EL element having a longer element lifetime is reduced. The first and second pixels have first and second color filters that transmit a part of the light of the first and second color components.
The first and second organic EL elements emit the radiance of the light of the first and second color components transmitted through the first and second color filters. The organic EL display device according to claim 9, wherein the filter efficiency is calculated by dividing by the radiance of light of the two color components.   The organic EL display device according to claim 14, wherein the number of pixels having an organic EL element having a higher filter efficiency is reduced.

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