JP2014127353A - El display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deterioration in picture quality due to color mixture even in a high definition or compact display device in which individual pixels are fine, in a color filter type EL display device.SOLUTION: An EL display device includes: an array substrate 1 including lower electrodes 4 formed on a front face per each pixel, a pixel separation film 5 separating the lower electrodes 4, and a white light emitting EL layer 6 formed on the upper layer of the lower electrodes 4 and the pixel separation film 5; a sealing substrate 9 including a black matrix 10, color filters 11R, 11G, 11B, and an overcoat layer 12, on the rear face; and a sealing layer 8 filled between the array substrate 1 and the sealing substrate 9, while a portion having a thickness different from other portion is formed in the overcoat layer 12.

Description

  The present invention relates to an EL display device.

  Currently, various types of electroluminescence (hereinafter referred to as “EL”) display devices have been developed and put into practical use. In particular, when a high-definition and small size is required such as mounting a full-color EL display device on a small device such as a portable device, the size of each pixel is reduced, and an EL layer that is a light-emitting layer is provided. It becomes difficult to paint separately on the pixels having different colored light.

  Accordingly, a color filter type EL display device has been proposed. As shown in FIG. 1, the EL layer 6 which is a light emitting layer formed on the array substrate 1 of the top emission type EL display device 400 is made to be a white light emitting common layer across all pixels, and sealed. Color filters 11R, 11G, and 11B, which are color elements, are provided on a sealing substrate 9 disposed with a stop layer 8 therebetween. As indicated by an arrow A in the figure, the white light generated from the EL layer 6 is emitted and recognized as green light by passing through the green color filter 11G.

A partial cross-sectional view showing a pixel portion of the conventional color filter type top emission EL display device 400 shown in FIG. 1 includes a circuit layer 2, a reflective layer 3,
A lower electrode 4, a pixel separation film 5, an EL layer 6, and an upper electrode 7 are shown, and a black matrix 10, color filters 11 R, 11 G, and 11 B formed on a sealing substrate 9, an overcoat layer 12, and a columnar spacer 13 is shown.

  In the EL display device 400 shown in FIG. 1, as indicated by an arrow B in the figure, color mixing occurs when light rays emitted in an oblique direction from the EL layer 6 enter the adjacent color filter 11B. In a high-definition or small-sized display device in which individual pixels are fine, this color mixture becomes more conspicuous because the interval between adjacent pixels becomes narrow, and in some cases, this is a practical problem. To reduce the degree of color mixing, the distance from the EL layer 6 to the color filters 11R, 11G, and 11B may be shortened. However, the height of the columnar spacer 13 that determines the thickness of the sealing layer 8 depends on the manufacturing process. There is a limit and cannot be lower than a certain level. Although it is conceivable to omit the columnar spacers 13 and make the sealing layer 8 thin, in that case, the influence of the unevenness on the surface of the array substrate 1 becomes strong, and the resin forming the sealing layer 8 is replaced with the array substrate 1. It is difficult to evenly fill between the sealing substrates 9.

  In order to solve the above-mentioned problem of color mixing, for example, Patent Document 1 proposes to provide a light-shielding portion that also serves as a spacer between each light emitting pixel and another light emitting pixel.

JP 2002-299044 A

  In the technique of Patent Document 1, a black resin material is used for the light shielding member and is processed into a desired pattern by a technique such as etching. However, in the case of a thick film that also serves as a spacer, the film profile tends to be tapered or undercut at the time of etching, and fine processing is difficult. Further, since the black resin material has a low ultraviolet transmittance, photolithography processing by making the black resin material itself photosensitive is difficult in the case of a thick film. For this reason, the technique described in this document cannot be applied to a high-definition or small-sized display device in which individual pixels are fine.

  The present invention has been made in view of such a viewpoint, and an object of the present invention is to reduce image quality deterioration due to color mixing even in a high-definition or small-sized display device in which individual pixels are fine in a color filter type EL display device. It is to reduce.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  (1) An array including a lower electrode formed for each pixel on the front surface, a pixel separation film separating the lower electrode, and a white light emitting EL layer formed on the lower electrode and the pixel separation film. A substrate, a black matrix on the rear surface, a color filter, a sealing substrate having an overcoat layer, and a sealing layer filled between the array substrate and the sealing substrate, and the overcoat layer And an EL display device provided with portions having different thicknesses.

  (2) In (1), the portion having a different thickness is a thin film portion where the thickness of the overcoat layer is thin or an opening portion where the overcoat layer is removed, and the thin film portion or the An EL display device in which a columnar spacer is formed in an opening portion.

  (3) The EL display device according to (2), wherein the columnar spacer is formed at a position not overlapping the color filter in a plan view.

  (4) The EL display device according to (1), wherein the portion having the different thickness is a protruding portion formed at a position overlapping the black matrix in a plan view.

  (5) The EL display device according to (1), wherein the portions having different thicknesses are provided in a shape complementary to the concavo-convex structure on the front surface of the array substrate.

  According to the above (1), in a color filter type EL display device, it is possible to reduce image quality degradation due to color mixing even in a high-definition or small-sized display device in which individual pixels are fine.

  According to (2) above, the height of the columnar spacer can be substantially reduced.

  According to the above (3), the height of the columnar spacer can be further reduced substantially.

  According to the above (4), the columnar spacer can be replaced by the shape of the overcoat layer.

  According to the above (5), filling of the resin forming the sealing layer between the array substrate and the sealing substrate can be performed smoothly.

It is a fragmentary sectional view showing a pixel portion of a conventional color filter type top emission type EL display device. 1 is a schematic exploded perspective view of an EL display device according to a first embodiment of the present invention. 1 is a partial cross-sectional view showing a pixel portion of an EL display device according to a first embodiment of the present invention. It is a fragmentary sectional view which shows the columnar spacer vicinity in the modification of the EL display apparatus which concerns on the 1st Embodiment of this invention. It is a fragmentary sectional view which shows the pixel part of the EL display apparatus which concerns on the 2nd Embodiment of this invention. It is a fragmentary sectional view which shows the pixel part of the EL display apparatus which concerns on the 3rd Embodiment of this invention.

  Hereinafter, an EL display device 100 according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic exploded perspective view of the EL display device 100 according to the first embodiment of the present invention. In the EL display device 100, a rectangular display area 21, which is an area where the pixels 20 are arranged, is provided on the front surface of the rectangular array substrate 1. A scanning circuit 22 is disposed adjacent to one of the left and right sides or both sides of the display area 21. In the present embodiment, the scanning circuit 22 is provided only on the left side of the display area 21. A number of scanning signal lines 23 extend from the scanning circuit 22 to the display area 21. As shown in the figure, the scanning circuit 22 may be provided by directly forming the circuit itself on the surface of the array substrate 1 by a so-called SOG (System On Glass) method or by mounting a semiconductor chip. It may be provided. A drive circuit 24 is provided adjacent to the front side of the display area 21. A large number of video signal lines 25 extend from the drive circuit 24 to the display area 21 and are orthogonal to the scanning signal lines 23. One pixel 20 is arranged in connection with the scanning signal line 23 and the video signal line 25. The drive circuit 24 may be formed and provided directly on the surface of the array substrate 1 in the same manner as the scanning circuit 22, but in this embodiment, the drive circuit 24 is provided by mounting a semiconductor chip. An FPC (Flexible Printed Circuit) 26 is connected to the drive circuit 24 so that image data is supplied to the drive circuit 24 from an external device.

  Further, a sealing substrate 9 is disposed on the front side of the array substrate 1. On the rear surface of the sealing substrate 9, color filters 11R, 11G, and 11B are formed at positions corresponding to the respective pixels 20 in the display area 21 (shown by broken lines in the figure). Further, the sealing substrate 9 is smaller in size than the array substrate 1, and the drive circuit 24 and the FPC 26 are exposed without being covered by the sealing substrate 9. In the present embodiment, the dimension of the sealing substrate 9 in the depth direction (long side) in the figure is smaller than the dimension of the array substrate 1 in the depth direction, and the width direction (short side) of the sealing substrate 9 in the figure. These dimensions are the same as the dimensions of the array substrate 1 in the width direction. In this specification, “front surface” is used as a term indicating a surface of the EL display device 100 facing the observer, and “rear surface” is a surface facing the opposite direction.

  Image data supplied from an external device is converted into a voltage signal indicating the luminance of each pixel 20 by the driving circuit 24 and output to the video signal line 25, and corresponds to the scanning signal line 23 selected by the scanning circuit 22. Supplied to the pixel 20. The pixel 20 emits light with luminance according to the supplied voltage signal by a pixel circuit provided in each pixel 20. In this way, the EL display device 100 forms an image in the display area 21 by the large number of pixels 20 provided in a grid pattern in the display area 21 emitting light with luminance corresponding to given image data.

  FIG. 3 is a partial cross-sectional view showing a pixel portion of the EL display device 100 according to the first embodiment of the present invention.

  In the EL display device 100, a large number of pixels are regularly arranged on the insulating array substrate 1, and an image is formed by controlling the light emission amount of the EL layer 6 at a position corresponding to each pixel. Therefore, on the array substrate 1, electrical circuits including TFTs (Thin Film Transistors) for controlling the amount of current flowing to each pixel are regularly arranged (in the case of this embodiment, in a lattice shape). Circuit layer 2 is formed. The array substrate 1 is a glass substrate in this embodiment, but the material is not particularly limited as long as it is an insulating substrate, and may be a synthetic resin or other materials. Moreover, the transparency and the opaqueness are not questioned.

  The circuit layer 2 includes an appropriate insulating layer, wiring composed of scanning signal lines, video signal lines, power supply lines, ground lines, and the like, and TFTs composed of gate, source, and drain electrodes and semiconductor layers. Since the electric circuit constituting the circuit layer 2 and its cross-sectional structure are well known, the details thereof are omitted here, and these are simplified and shown only as the circuit layer 2.

  On the circuit layer 2, the reflective layer 3 is provided independently for each pixel. The reflective layer 3 has a function of reflecting light emitted from the EL layer 6 provided in the upper layer. The reflective layer 3 may be formed of an appropriate metal film, and for example, aluminum, chromium, silver, or an alloy thereof may be used. In addition, you may abbreviate | omit the reflection layer 3 as what serves as the lower electrode 4 demonstrated below. Alternatively, when the reflective layer 3 and the lower electrode 4 are insulated by an arbitrary insulating layer or the like, the reflective layer 3 does not necessarily have to be provided independently for each pixel. For example, the display region 21 (see FIG. 2). ) It may be provided so as to cover the entire surface.

  A lower electrode 4 is provided for each pixel on the upper layer of the reflective layer 3. The lower electrodes 4 are separated from each other by a pixel isolation film 5 (also called a bank) and insulated. The lower electrode 4 is a transparent conductive film, and is preferably a conductive metal oxide such as ITO (indium tin oxide) or InZnO (zinc tin oxide), or a metal such as silver mixed in the conductive metal oxide. Used for. When the lower electrode 4 also serves as the reflective layer 3, it may be a simple metal thin film. The pixel isolation film 5 may be any insulating material, and may be formed of an organic insulating material such as polyimide or acrylic resin, or silicon nitride. The pixel separation film 5 is disposed along the boundary of each pixel and separates each pixel from each other.

  An EL layer 6 is provided on the lower electrode 4 and the pixel separation film 5. The EL layer 6 is not independent for each pixel, and is provided so as to cover the entire display region 21 (see FIG. 2). Further, the emission color of the EL layer 6 is white. Such white light emission is generally obtained as a composite color by laminating a plurality of colors, for example, red, green, and blue, or EL materials that emit yellow and blue. The specific configuration of the layer 6 is not particularly limited, and any single layer / stacked layer structure or layer structure may be used as long as white light emission can be obtained as a result. Moreover, although the material which comprises EL layer 6 may be organic or inorganic, in this embodiment, the organic material is used.

  Further, an upper electrode 7 is provided on the EL layer 6. The upper electrode 7 is also independent of each pixel and is provided so as to cover the entire display area 21 (see FIG. 2). The upper electrode 7 is also a transparent conductive film, a conductive metal oxide such as ITO (indium tin oxide) or InZnO (zinc tin oxide) mixed with a metal such as silver or magnesium, a metal thin film such as silver or magnesium, A laminate of conductive metal oxides or a simple metal thin film is preferably used.

  With this structure, the upper electrode 7 located on the front surface of the array substrate 1 has a structure with irregularities. In FIG. 3, the portion corresponding to the pixel isolation film 5 is shown as convex and the other portions are shown as flat concaves, but in addition to this, TFTs and through-holes formed in the circuit layer 2 are shown. The unevenness due to various structures is reflected. Note that a protective layer made of any material may be formed on the upper layer of the upper electrode 7, but in this case, the protective layer has the same uneven structure as the upper electrode 7.

  A sealing layer 8 is provided on the front side of the array substrate 1 to prevent and protect oxygen and moisture from entering each layer including the EL layer 6. The sealing layer 8 may be composed of an organic material having excellent protection performance, or the sealing layer 8 may be composed by laminating a plurality of different materials. A transparent material is selected for the sealing layer 8.

  A sealing substrate 9 is provided so as to face the array substrate 1 with the sealing layer 8 interposed therebetween. The rear surface of the sealing substrate 9, that is, the surface facing the array substrate 1, serves as a pixel boundary. A black matrix 10 is formed in the portion, and color filters 11R, 11G, and 11B of colors corresponding to the light emission colors of the pixels are formed at positions corresponding to the pixels so as to cover the black matrix 10. The sealing substrate 9 is made of glass or synthetic resin and is transparent to visible light. The black matrix 10 may be any material that is black with respect to visible light, that is, a light-absorbing material. For example, a material obtained by mixing carbon in polyimide or an acrylic synthetic resin is used. It's okay. The color filters 11R, 11G, and 11B are colored red, green, and blue, respectively, by mixing a dye material into an arbitrary synthetic resin, for example, an acrylic synthetic resin.

  Further, an overcoat layer 12 is formed so as to cover the color filters 11R, 11G, and 11B, and the color filters 11R, 11G, and 11B are protected and the rear surface of the sealing substrate 9 in the display region 21 is flattened. . In the position where the overcoat layer 12 overlaps with the black matrix 10 in plan view, an opening portion 14 where the overcoat layer 12 is partially removed is provided as a portion having a different thickness of the overcoat layer 12. The color filters 11R, 11G, and 11B are exposed from the overcoat layer 12. Further, columnar spacers 13 are formed in the opening portion 14. For the overcoat layer 12 and the columnar spacer 13, an appropriate synthetic resin such as acrylic or polyimide may be used.

  With such a structure, the EL layer 6 at the position corresponding to each pixel of the EL display device 100 has the amount of holes and electrons controlled by the electric circuit arranged in the circuit layer 2 so that the lower electrode 4 and the upper electrode When injected by 7, light is emitted with a luminance corresponding to the amount of current. The polarities of the lower electrode 4 and the upper electrode 7 are not particularly limited, but in the present embodiment, the lower electrode 4 functions as an anode and the upper electrode 7 functions as a cathode. As is clear from the above description and FIG. 1, the EL display device 100 is a so-called top emission type, and emits light to the front side of the array substrate 1.

  Here, the sealing layer 8 is formed by filling the sealing resin between the array substrate 1 and the sealing substrate 9 and then curing, and at that time, the array substrate 1 and the sealing substrate 9 are pressed against each other. Therefore, the thickness of the sealing layer 8 is mainly determined by the height of the columnar spacers 13. In the present embodiment, since the opening 14 is provided in the overcoat layer 12 at the position where the columnar spacer 13 is formed, the height of the columnar spacer 13 is substantially equal to the thickness of the overcoat layer 12. It is low. Therefore, the distance between the array substrate 1 and the sealing substrate 9 is shortened by the thickness of the overcoat layer 12, and the degree of color mixing is reduced.

  In this embodiment, the opening portion 14 from which the overcoat layer 12 is removed is provided at the position where the columnar spacer 13 is formed. Instead, the thickness of the opening portion 12 is removed without completely removing the overcoat layer 12. You may make it provide the thin film part which reduced this. The opening portion 14 and the thin film portion are formed by performing etching or so-called half exposure using a photolithography technique when the overcoat layer 12 is formed.

  In the example shown in FIG. 3, the columnar spacers 13 are formed on the surfaces of the color filters 11R, 11G, and 11B. However, as shown in FIG. 4, the columnar spacers 13 are not overlapped with the color filters 11R, 11G, and 11B. It may be formed directly on the surface of the matrix 10. If the width of the black matrix 10 is thick enough to allow the columnar spacers 13 to be formed even if the overlap with the color filters 11R, 11G, and 11B is taken into account, the columnar spacers 13 are further formed by adopting such a structure. Is substantially lower.

  In FIG. 3, the columnar spacers 13 are shown as being in contact with the surface (upper electrode 7) of the array substrate 1, but the columnar spacers 13 do not necessarily have to hit the surface of the array substrate 1.

  Next, an EL display device 200 according to a second embodiment of the present invention will be described with reference to the drawings. The appearance of the EL display device 200 is the same as that shown in FIG. 2 as that of the EL display device 100 according to the first embodiment. In the description of the EL display device 200 according to the present embodiment, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 5 is a partial cross-sectional view showing a pixel portion of an EL display device 200 according to the second embodiment of the present invention. In the EL display device 200, in the position overlapping the black matrix 10 of the overcoat layer 12 in a plan view, as a portion where the thickness of the overcoat layer 12 is different, here, a protruding portion where the thickness of the overcoat layer 12 is partially thick. 15 is provided. The protruding portion 15 substitutes for the function of the columnar spacer in the background art or the first embodiment described above, and plays a role of determining the thickness of the sealing layer 8 when the EL display device 200 is manufactured. ing.

  When the overcoat layer 12 is formed, the protruding portion 15 can be formed by performing etching or so-called half exposure using a photolithography technique. That is, in the case of etching, the entire overcoat layer 12 may be formed with the same thickness as the protruding portion 15, and then the portion other than the protruding portion 15 may be removed by etching to reduce the thickness. Further, in the case of half exposure, after the resin for forming the overcoat layer 12 is applied on the sealing substrate 9, the portions other than the protruding portions 15 are subjected to half exposure with a halftone mask and then developed. . Since the thickness of the overcoat layer 12 can be determined relatively freely, the height of the columnar spacer can be substantially reduced even in this way.

  Subsequently, an EL display device 300 according to a third embodiment of the present invention will be described with reference to the drawings. The appearance of the EL display device 300 is also the same as that of the EL display device 100 according to the first embodiment shown in FIG. In describing the EL display device 300 according to the present embodiment, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 6 is a partial cross-sectional view showing a pixel portion of an EL display device 300 according to the third embodiment of the present invention. In the EL display device 300 according to the present embodiment, a concavo-convex shape that is complementary to the concavo-convex structure on the front surface of the array substrate 1 is provided on the rear surface of the overcoat layer 12 as a portion having a different thickness of the overcoat layer 12. Yes. That is, a concave portion is formed on the rear surface of the overcoat layer 12 in a portion where the front surface of the array substrate 1 is convex, such as immediately above the pixel separation film 5, and a convex portion is formed on the rear surface of the overcoat layer 12 in other flat and concave portions. It is formed. As a result, the distance d1 between the front surface of the array substrate 1 and the rear surface of the sealing substrate 9 at the portion where the front surface of the array substrate 1 is convex (which is equal to the thickness of the sealing layer 8), and the front surface of the array substrate 1 The difference between the distance d2 between the front surface of the array substrate 1 and the rear surface of the sealing substrate 9 in the concave portion is reduced or equalized. This also means that the in-plane thickness change of the sealing layer 8 is reduced.

  According to such a structure, when the sealing resin is filled between the array substrate 1 and the sealing substrate 9 in order to form the sealing layer 8, the space between the front surface of the array substrate 1 and the rear surface of the sealing substrate 9. Occurrence of a region not filled with the sealing resin due to the uneven distance is prevented.

  The uneven shape in the overcoat layer 12 in this embodiment is also formed by performing etching or so-called half exposure using a photolithography technique when forming the overcoat layer 12. Can do.

  In addition, the specific shape, arrangement, number, and the like of each member shown in the embodiment described above are examples, and the present invention is not limited to these. In carrying out the present invention, those skilled in the art may arbitrarily design and change the shape and the like of each member according to the embodiment.

  DESCRIPTION OF SYMBOLS 1 Array substrate, 2 Circuit layer, 3 Reflective layer, 4 Lower electrode, 5 Pixel separation film, 6 EL layer, 7 Upper electrode, 8 Sealing layer, 9 Sealing substrate, 10 Black matrix, 11R, 11G, 11B Color filter , 12 Overcoat layer, 13 Columnar spacer, 14 Opening portion, 15 Protrusion portion, 20 Pixel, 21 Display area, 22 Scan circuit, 23 Scan signal line, 24 Drive circuit, 25 Video signal line, 26 FPC, 100, 200, 300,400 EL display device.

Claims (5)

An array substrate comprising a lower electrode formed for each pixel on the front surface, a pixel separation film separating the lower electrode, and a white light emitting EL layer formed on the lower electrode and the pixel separation film;
A black matrix on the back, a color filter, a sealing substrate with an overcoat layer,
A sealing layer filled between the array substrate and the sealing substrate;
Have
An EL display device in which portions having different thicknesses are provided on the overcoat layer. The portion having a different thickness is a thin film portion where the thickness of the overcoat layer is reduced or an opening portion where the overcoat layer is removed,
The EL display device according to claim 1, wherein a columnar spacer is formed in the thin film portion or the opening portion.   The EL display device according to claim 2, wherein the columnar spacer is formed at a position that does not overlap the color filter in plan view.   2. The EL display device according to claim 1, wherein the portion having the different thickness is a protruding portion formed at a position overlapping the black matrix in a plan view.   2. The EL display device according to claim 1, wherein the portions having different thicknesses are provided so as to have a complementary shape to the concave-convex structure on the front surface of the array substrate.

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