JP2009020362A - Organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-lived organic EL display device by preventing seizure of pixels of fixed display parts at the upper and lower ends of a display part. <P>SOLUTION: In the organic EL display device 10, pixels 181 in a central part 141 of the display part 14 of an organic EL display element 12 have a structure different from that of pixels 182 in a remaining part 142. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic EL display device, and is particularly intended to reduce burn-in of pixels that appear prominently in a partial region.

There exists patent document 1 in the conventional organic electroluminescence display.
Patent Document 1 discloses a four-color light-emitting device, that is, an R-G-B-W-W method in which white (W) organic EL elements are added to red (R), green (G), and blue (B) organic EL elements. A technique relating to improvement of the driving circuit for the four-color light emitting device is disclosed. In particular, it is disclosed that W is an RGB laminate.
JP 2007-41578 A

Organic EL display devices are used in mobile phone display devices, digital still camera display devices, and music player display devices. In these applications, a specific image such as a task bar (for example, a fixed display pattern such as an antenna and a remaining battery level) is often displayed. Such a pattern has a high display frequency and emits light with high luminance. Therefore, there was a problem that image sticking is likely to occur. As a countermeasure, when not in use, the entire display area is controlled to be extinguished in a predetermined time (for example, about 15 seconds). Although this extinction setting can be expected to be effective as a countermeasure against burn-in of the icon part for fixed display on the task bar, it is necessary to re-operate the start button etc. to redisplay the display area, and the operability is not reduced. Inevitably, there was a problem of delay in response time.
An object of the present invention is to provide a long-life organic EL display device having excellent display characteristics by preventing image sticking in a frequently used region.

Among the means included in the present application, typical means are as follows.
(1) In an organic EL display device in which a subpixel is configured by an organic EL element including an organic light emitting layer between a pair of electrodes, a first subpixel that emits a first color and a second that emits a second color A first region that includes a subpixel, a third subpixel that emits a third color in one pixel, and a second region that constitutes one pixel by a subpixel that emits fewer colors than the first region; In this way, by reducing the colors used, it is possible to increase the number of pixels of the same color. Since the number of sub-pixels that emit light increases even if the amount of current flowing through each sub-pixel is reduced, even if the luminance of each sub-pixel is lowered, the same brightness can be maintained for the entire second region. Life expectancy can be realized.
(2) In (1), when the second area is the end of the display area, the pixels of the second area can be allocated to a frequently used part such as a task bar. It is effective in extending the life of
(3) In (1), a sub-pixel in the first area, which is provided with a color filter between the display area and the organic EL element, and is a sub-pixel in the second area, the sub-pixel in the display area and the organic EL element. If the color filter is not provided between them, the transmittance of the second region is increased, and thus the luminance is more easily increased than that of the second region.
(4) In an organic EL display device in which a subpixel is configured by an organic EL element including an organic light emitting layer between a pair of electrodes, a first subpixel that emits a first color and a second color that emit light A second sub-pixel, a third sub-pixel that emits a third color, and a fourth sub-pixel that emits a fourth color, wherein some of the pixels in the display area include the first sub-pixel, The second subpixel is composed of the third subpixel, and the other pixels in the display area are composed of the fourth subpixel. In this way, by reducing the colors used, it is possible to increase the number of pixels of the same color. Since the number of sub-pixels that emit light increases even if the amount of current flowing through each sub-pixel is reduced, even if the luminance of each sub-pixel is lowered, the same brightness can be maintained for the entire second region. Life expectancy can be realized. Further, since the stacked structure is adopted in the second region, the subpixels in the second region are thicker than the subpixels in the first region. Therefore, when the same voltage is applied, a smaller current flows in the second region than in the first region. Therefore, if a fixed pattern such as an icon is displayed in the second area, a long-life organic EL display device with excellent display characteristics that reduces partial image sticking in the display area can be realized.
(5) The pixel including the fourth subpixel in (4) is present in either or both of the upper and lower sides of the display area. This arrangement is suitable for displaying a fixed pattern such as an icon and is more effective.
(6) In (4), the first subpixel emits red, the second subpixel emits green, the third subpixel emits blue, and the fourth subpixel emits white.

  According to the present invention, there is provided a long-life organic EL display device having excellent display characteristics in which unevenness of the entire display area is suppressed by reducing the burning of a part of the display area.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings of the examples. In the following embodiments, a top emission type organic EL display device is taken as an example, but the same applies to a bottom emission type.

FIG. 1 to FIG. 6 are schematic views for explaining the configuration of an embodiment of the organic EL display device of the present invention. FIG. 1A is a schematic plan view of the organic EL display device, and FIG. 2A is a cross-sectional view taken along the line AA in FIG. 1A, FIG. 2B is a cross-sectional view taken along the line BB in FIG. 3 is an enlarged cross-sectional view showing a part of FIG. 2, and FIGS. 4 to 6 are enlarged cross-sectional views of the organic EL layer.
1 to 6, the organic EL display device 10 includes an organic EL display element 12 in a housing 11. Reference numeral 13 denotes a control button, 14 denotes a display area, and the display area 14 has a substantially rectangular shape and is composed of the sealing substrate 15 of the organic EL display element 12.
The central portion 141 of the rectangular display area 14 displays main information including a moving image or the like as a main display portion, and the remaining portions 142 displayed by hatching are present at the upper and lower end portions of the display portion 14. It is called a task bar, and is generally configured to display a fixed pattern, for example, a sub display such as a battery remaining amount display and antenna sensitivity.

  As schematically shown in FIGS. 2A and 2B, the organic EL display element 12 includes the sealing substrate 15 preferably made of a transparent glass material, an insulating substrate 16 opposed thereto, an adhesive, and the like. The sealing material 17 is provided, the sealing substrate 15 and the insulating substrate 16 are sealed with the sealing material 17, and the internal space 19 in which the display pixels 18 are arranged is isolated from the external atmosphere. . A number of pixels 18 for displaying an image displayed on the display unit 14 are disposed on the main surface 161 of the insulating substrate 16. These pixels 18 are composed of a combination of a pixel 181 corresponding to the central portion 141 and a pixel 182 corresponding to the remaining portion 142. The pixel 181 corresponding to the central portion 141 includes red pixels 181R, blue pixels 181B, and green pixels 181G having three primary red, blue, and green light emitting EL display layers 18R, 18B, and 18G arranged in a specific arrangement. It has a set structure. Each of these pixels 181R to 181G includes electrodes on the upper and lower sides. In the display area, each pixel emits light in red, blue, and green, and a plurality of colors are displayed.

  On the other hand, the pixel 182 corresponding to the remaining portion 142 has a configuration in which the red light emitting EL display layer 18R, the blue light emitting EL display layer 18B, and the green light emitting EL display layer 18G are stacked. Each of the pixels 182 also includes electrodes on the upper and lower sides. In this laminated structure, the display unit 14 has a white or black monochrome display, and has a different display color number from the central unit 141.

An example of the configuration of the insulating substrate 16 on which the pixels 18 are mounted is shown in FIG. In FIG. 3, reference numeral 21 is a counter electrode (anode electrode), 22 is a pixel electrode (cathode electrode), 23 is a bank, 24 is an organic EL light emitting layer, 25 is an insulating planarizing film, 26 is an insulating film, 27 Is a first gate, 28 is a second gate, 29 is a gate insulating film, 30 is a wiring between switching elements, 31 is a wiring between switching elements (a part also serving as a light shield), and 16 is an insulating substrate. Between the insulating film 26 and the pixel electrode 22, there is a reflective member in which aluminum is laminated on a molybdenum tungsten alloy, but this is not shown. The insulating substrate 16 includes a substrate preferably made of transparent glass with silicon nitride SiN and silicon oxide SiO ₂ formed on the main surface, and serves as the TFT substrate described above. A first gate 27 is formed by patterning the semiconductor film in the switching element region on the silicon oxide SiO ₂ film. The first gate 27 is a film obtained by annealing an amorphous silicon film, and a polysilicon film is preferable from the viewpoint of mobility. A gate insulating film 29 is formed so as to cover the first gate 27, a second gate 28 is patterned on the gate insulating film 29, and an insulating planarizing film 25 is formed so as to cover the second gate 28. The second gate 28 is made of MoW. A wiring 30 is a drain electrode of the switching element, and a wiring 31 is a source electrode, and is connected to the first gate 27 through a contact hole that penetrates the planarization film 25 and the gate insulating film 29. The wiring 30 and the wiring 31 are MoW / AlSi / MoW laminated films. An insulating film 26 is formed to cover the inter-switch wiring 30 and the inter-switch wiring / shield member 31. A flat pixel electrode 22 connected to the inter-switch wiring / shield member 31 through a contact hole provided in the insulating film 26 extends to the light emitting area.
The pixel electrode 22 is made of an Mg—Ag alloy. The pixel electrode 22 may be configured to improve the light absorption function by blackening the surface facing the light emitting area.

  On the pixel electrode 22, an organic EL light emitting layer 24 constituting a light emitting area is disposed so as to be surrounded by a bank-like bank 23. The organic EL light emitting layer 24 is arranged in a matrix in the X direction and the Y direction.

  On the organic EL light emitting layer 24 constituting the light emitting area, a translucent counter electrode 21 made of, for example, an ITO film is disposed. Here, the counter electrode 21 is an anode electrode. The counter electrode 21 is arranged on the organic EL light emitting layer 24 so as to continuously cover the top surface from the side wall of the bank 23.

  The bank 23 is made of an inorganic insulating material such as a silicon oxide film or a silicon nitride film, and has a shape having an opening (bank opening) in a light emitting area. Therefore, the bank 23 has a shape having a recess in its opening.

  The bank 23 has a bank shape surrounding the pixel 18, and an organic EL light emitting layer 24 is filled in a region surrounded by the bank 23.

  The upper electrode 21 is formed so as to cover the organic EL light emitting layer in common.

  By applying an electric field between the lower electrode 22 and the upper electrode 21 to the pixel configured as described above, colored light is emitted in the direction of the thick arrow 32.

  An example of the organic EL light emitting layer 24 disposed in the bank 23 is shown in FIG. This example is a top emission type.

  In FIG. 4, the organic EL light-emitting layer 24 has an electron transport layer 33 disposed in contact with the pixel electrode 22, and a light-emitting layer 34, a hole transport layer 35, and a hole injection layer 36 are sequentially stacked on the organic EL light-emitting layer 24. A counter electrode 21 is formed on the entire surface. The organic EL light emitting layer 24 is formed in contact with the inner edge of the bank opening.

  In the above configuration, the transparent counter electrode 21 functions as an anode and the pixel electrode 22 functions as a cathode. The counter electrode 21 that is an anode may be made of a transparent electrode material having a high work function. However, other transparent conductive materials may be used. On the other hand, for the pixel electrode 22 which is a cathode, Al, Mg, Mg—Ag alloy, Al—Li alloy, or the like having a low work function can be used. Further, in order to improve the characteristics, an alkali metal compound such as an extremely thin lithium fluoride LiF may be used between the organic layer and not an Al single substance. Note that the pixel electrode 22 is preferably made of a material having low light reflectance in order to suppress reflection of light emitted from the light emitting layer.

  The light emitting layer 34 is made of a material that emits light in a desired color when a predetermined voltage is applied between the transparent counter electrode 21 that is an anode and the pixel electrode 22 that is a cathode.

Another example of the organic EL light emitting layer 24 is shown in FIGS. First, in FIG. 5, the organic EL light-emitting layer 24 has a three-layer structure of an electron transport layer 33, a light-emitting layer 34, and a hole transport layer 35, on which a counter electrode 21 made of a V ₂ O ₅ material is laminated, The EL light emitting layer 24 is configured to have a light absorption function in the electron transport layer 33 on the back side of the light emitting layer 34. Other configurations may be the same as those in FIG. 4 or the pixel electrode 22 may not have a light absorption function.

  Next, in another example of the organic EL light emitting layer 24 shown in FIG. 6, the pixel electrode 22 serving as the anode electrode is disposed on the back surface side, and the counter electrode 21 serving as the cathode electrode is disposed on the front surface side. The pixel electrode 22 is configured to have a light absorption function as in FIG. In the organic EL light emitting layer 24 of this example, a hole injection layer 36, a hole transport layer 35, a light emitting layer 34, and an electron transport layer 33 are sequentially laminated from the pixel electrode 22 side. With this configuration, the counter electrode 22 disposed on the front surface (display surface) side uses a transparent electrode.

  FIG. 7 is a schematic cross-sectional view for explaining the configuration of another embodiment of the organic EL display device of the present invention. The same reference numerals are given to the same functions or the same parts as those in the above-mentioned drawings. In FIG. 7, in the second embodiment, the pixel 181 that displays the central portion 141 of the display unit 14 has a configuration in which red, blue, and green color filters 18CR, 18CB, and 18CG are stacked on the white light emitting EL layer 18W, respectively. In the region, each pixel emits light in red, blue and green, and a plurality of colors are displayed.

  On the other hand, the portion of the pixel 182 corresponding to the remaining portion 142 has only the white light emitting EL display layer 18W. Each of the pixels 182 also includes electrodes on the upper and lower sides. In this stacked structure, the remaining portion 142 has a white or black monochrome display, and has a different display color number from the central portion 141.

  FIG. 8 is a schematic cross-sectional view for explaining the configuration of still another embodiment of the organic EL display device of the present invention. The same reference numerals are given to the same functions or the same parts as those in the above-described drawings. In FIG. 8, in Example 3, the pixel 181 that displays the central portion 141 of the display unit 14 is a red pixel 181 </ b> R and a blue pixel 181 </ b> B having three primary colors of red, blue, and green light emitting EL display layers 18 </ b> R, 18 </ b> B, and 18 </ b> G. , Green pixels 181G are arranged side by side in a specific arrangement. Each of these pixels 181R to 181G includes electrodes on the upper and lower sides. In the display area, each pixel emits light in red, blue, and green, and a plurality of colors are displayed.

  On the other hand, the pixel 182 corresponding to the remaining portion 142 has a configuration in which two of the three primary colors, in this example, blue and green light-emitting EL display layers 18B and 18G are stacked, and the display region is blue. The combined color light of green is displayed, and the display color number is different from that of the central portion 141.

  Various combinations such as red-green, red-blue, etc. are possible for the combination of the two colors of light-emitting EL display layers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining a configuration of an example of an organic EL display device according to the present invention, FIG. 1A is a schematic plan view of the organic EL display device, and FIG. 1B is a side view of FIG. . 2A is a schematic cross-sectional view taken along line AA in FIG. 1A, and FIG. 2B is a schematic cross-sectional view taken along line BB in FIG. 1A. It is a schematic cross section which expands and shows a part of FIG. It is a model expanded sectional view of an example of an organic electroluminescent light emitting layer. It is a model expanded sectional view of the other example of an organic electroluminescent light emitting layer. It is a model expanded sectional view of other examples of an organic electroluminescent light emitting layer. It is a schematic cross section explaining the structure of the other Example of the organic electroluminescence display of this invention. It is a schematic cross section explaining the structure of the further another Example of the organic electroluminescence display of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Organic EL display device, 12 ... Organic EL display element, 14 ... Display area, 141 ... Center part, 142 ... Remaining part, 15 ... Sealing substrate, 16 ... Insulating substrate, 17 ... sealing material, 18, 181, 182 ... pixel, 21 ... counter electrode, 22 ... pixel electrode, 23 ... bank, 24 ... organic EL light emitting layer.

Claims (6)

In an organic EL display device in which a sub-pixel is configured with an organic EL element including an organic light emitting layer between a pair of electrodes,
A first subpixel that emits a first color; a second subpixel that emits a second color; and a first region that includes a third subpixel that emits a third color in one pixel;
An organic EL display device comprising: a second region that constitutes one pixel with sub-pixels that emit fewer colors than the first region. In claim 1,
The organic EL display device, wherein the second region is an end of a display region. In claim 1,
The subpixel of the first region includes a color filter between the display region and the organic EL element,
The organic EL display device, wherein the sub-pixel of the second region is formed by stacking a display region and an organic EL element. In an organic EL display device in which a sub-pixel is configured with an organic EL element including an organic light emitting layer between a pair of electrodes,
A first subpixel emitting a first color;
A second sub-pixel emitting a second color;
A third subpixel emitting a third color;
A fourth subpixel emitting a fourth color;
With
A part of pixels of the display area includes the first subpixel, the second subpixel, and the third subpixel.
The other pixel in the display area is configured by the fourth sub-pixel. In claim 4,
The organic EL display device, wherein the pixels including the fourth sub-pixel are present in one or both of the upper and lower sides of the display area. In claim 4,
The organic EL display device, wherein the first subpixel emits red, the second subpixel emits green, the third subpixel emits blue, and the fourth subpixel emits white.

Images