JP2013047720A - Color filter and method for manufacturing color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter and a method for manufacturing the color filter, in which, when a plurality of colored transparent pixels constituting the color filter extend and overlap or adjoin to each other in a pixel boundary part, cracks are prevented from being generated in a transparent conductive film that covers the whole color array region of the colored transparent pixels, in particular, on the pixel boundary part.SOLUTION: A color filter comprises: three or more colors of monochromatic colored transparent pixels being arrayed in regular repetition of colors on a substrate; and a transparent conductive film provided to cover the whole surface of the color array region. Exclusively on a pixel boundary part where edges of pixels in two different colors from each other overlap or adjoin each other, an overcoat layer comprising a colored transparent pixel material in a color different from the above two colors constituting the pixel boundary part is disposed under the transparent conductive film.

Description

  The present invention relates to a color filter used for a liquid crystal display device or the like.

  Color liquid crystal display devices are rapidly spreading as thin and light display devices necessary for multicolor display, centering on computer terminals and television image displays. Various configurations have been proposed as a liquid crystal display panel that is a main part of a color liquid crystal display device, and a liquid crystal display panel for an active matrix drive type TN (Twisted Nematic) type or VA (Vertical Alignment) type display device. Is commonly used.

  The liquid crystal display panel for the TN type or VA type multicolor display device performs multicolor pixel division driving by the electrodes provided on each of the two substrates sandwiching the liquid crystal, and the liquid crystal is driven by the function of the liquid crystal alignment film. Selectively oriented to display the image. The structure on the side of the color filter (hereinafter abbreviated as CF) is, as shown in a schematic sectional view of a typical example in FIG. As a common electrode layer that provides colored transparent pixels such as red pixels 3r, green pixels 3g, and blue pixels 3b that selectively fill the openings to form color pixels to separate display colors and cover the entire effective area The transparent conductive film 4 is provided. Further, the liquid crystal display panel for the multicolor display device can be configured by covering the liquid crystal alignment film on the CF and performing alignment treatment, and then placing the liquid crystal display panel in contact with the liquid crystal.

  On the other hand, in particular, in order to realize high definition of a small color liquid crystal display device, the pitch of pixels is reduced and the line width of a black matrix (hereinafter abbreviated as BM) is being reduced. Conventionally, a colored transparent pixel overlapping on a BM hardly extends until it overlaps with a colored transparent pixel of a different color, and is arranged with a gap from the adjacent colored transparent pixel within the line width of the BM. In many cases, however, with the thinning of the BM, a design that allows colored transparent pixels of different colors to overlap each other on the BM has been made. As shown in FIG. It is likely to exhibit a cross-sectional shape with large irregularities.

  In the structure of the liquid crystal display panel, it is preferable to flatten the surface of the color filter in order to maintain high display quality of the panel. Accordingly, when it is allowed that different colored transparent pixels overlap on the BM as described above, the overlapping portion is polished in a later process, or the edge portion of the colored transparent pixels constituting the overlapping portion is gently set with respect to the BM surface. The effect of unevenness on the surface was reduced by means of providing a gentle slope (see Patent Documents 1 and 2).

JP-A-9-230124 JP 2006-227295 A

The fact that the colored transparent pixels of the color filter extend on the black matrix so that different colored transparent pixels overlap each other and are likely to cause surface irregularities is unavoidable even with the above measures. In addition, depending on the form of the arrangement of the colored transparent pixels, not only the overlapping of the two colored transparent pixels but also the overlapping of the three colored transparent pixels occurs, and the rise is further increased. In addition, a minute concave portion is likely to be generated at the edge portion of the colored transparent pixel in which the rising of the overlapping portion is increased.

  When a transparent conductive film is formed as a common electrode layer that covers the entire color arrangement region of the colored transparent pixels having such surface irregularities, including the black matrix, heat treatment during the production process or after the formation of the transparent conductive film, etc. In the step, cracks may occur in the transparent conductive film. In many cases, the crack starts from an overlapping portion or an adjacent portion of the colored transparent pixels on the black matrix surface. Also, it tends to easily extend from the starting point to the pixel surface of the black matrix opening, and when a color filter having cracks generated in the transparent conductive film is incorporated in the liquid crystal display panel, the liquid crystal alignment drive is not uniform. This causes display defects.

  The present invention is proposed in view of the above-mentioned problems, and the problem to be solved by the present invention is that a plurality of colored transparent pixels constituting a color filter extend or overlap each other at a pixel boundary portion. In such a case, the present invention provides a color filter that does not cause cracks on a transparent conductive film that covers the entire surface of the color array region of colored transparent pixels, particularly on the pixel boundary, and a method for manufacturing the same.

  As a means for solving the above-mentioned problems, the invention according to claim 1 is characterized in that colored transparent pixels of a single color are arranged in color by regular repetition of three or more colors on the substrate, and the entire surface of the color arrangement area is covered. A color filter provided with a transparent conductive film so as to cover, and is limited to a pixel boundary portion where two different pixel edge portions overlap or are adjacent to each other, and is colored in a color different from the two colors constituting the pixel boundary portion A color filter comprising an overcoat layer made of a transparent pixel material under a transparent conductive film.

  According to a second aspect of the present invention, in the color filter according to the first aspect, the pixel boundary portion is defined in advance by a black matrix pattern as a light-shielding base of the pixel edge portion.

  According to a third aspect of the present invention, the color arrangement of the colored transparent pixels consists of three colors of red, green and blue, and the overcoat layer is made of a blue material on the pixel boundary between the red pixel and the green pixel. The color filter according to claim 1, wherein the color filter is configured.

  According to a fourth aspect of the present invention, after forming colored transparent pixels in the order of red and green by photolithography, an overcoat layer made of the same material is formed simultaneously with the formation of blue pixels. The color filter manufacturing method according to claim 1, wherein the color filter is formed on a pixel boundary portion between a red pixel and a green pixel by a photolithography method.

  The present invention relates to a color filter provided with a transparent conductive film, and is limited to a pixel boundary portion where pixel edge portions of two different colors overlap or are adjacent to each other, and is colored transparently different from the two colors constituting the pixel boundary portion. Since the overcoat layer made of the pixel material is provided under the transparent conductive film, it is possible to provide a color filter that does not cause cracks in the transparent conductive film on the pixel boundary.

It is a schematic cross section which shows an example of the color filter of this invention. It is a schematic cross section showing an example of a conventional color filter. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram for demonstrating in detail the structure of the color filter of this invention by the state before transparent conductive film formation, Comprising: (a) is the expanded top view, (b) is further in the dotted-line circle of (a). It is sectional drawing expanded.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of the color filter of the present invention in a partially enlarged manner. The aspect ratio in the figure is exaggerated and greatly shows the vertical expansion in the film thickness direction.

  The color filter of the present invention is a color filter in which colored transparent pixels of a single color are arranged in color by regular repetition of three or more colors on the substrate 1 and a transparent conductive film 4 is provided so as to cover the entire surface of the color arrangement region. The overcoat layer 5 made of a colored transparent pixel material having a color different from the two colors constituting the pixel boundary portion is transparent, limited to the pixel boundary portion where the pixel edge portions of two different colors overlap or are adjacent to each other. It is provided below the conductive film 4.

  In this example, the pixel boundary portion shows a most general form preliminarily defined by the pattern of the black matrix (BM) 2 as a light-shielding base at the pixel edge portion. BM can improve display quality by partitioning each pixel of a liquid crystal display panel by shading, and is a photo that is exposed and developed after applying a photosensitive resin containing a light-shielding pigment such as carbon. A pattern can be formed by a lithography method or by a photolithography method and an etching method after forming an inorganic thin film such as a metal or a metal oxide.

  In this example, the color arrangement of the colored transparent pixels is composed of three colors of a red pixel 3r, a green pixel 3g, and a blue pixel 3b, and the overcoat layer 5 has a blue material on the pixel boundary portion between the red pixel 3r and the green pixel 3g. Consists of. The colored transparent pixel can be formed by a photolithography method using a transparent resin having photosensitivity containing a pigment, in the same manner as in the first manufacturing method described for the BM pattern formation, using a desired coloring pigment as a material. In consideration of the arrangement of each color pixel and the alignment accuracy of the BM, it is necessary to overlap a part of the BM line width so as not to create a gap in the opening, but the pixels are narrowed and the BM is thinned. As in this example, which is often adopted when advancing, a design is also made in which different colored transparent pixels adjacent to each other extend on the BM surface and have overlapping portions.

  The transparent conductive film 4 is formed of a thin film such as ITO (indium / tin / oxide), and a general thin film forming method such as a sputtering method or a vacuum evaporation method is used. The phenomenon of cracks in the transparent conductive film is seen as a result of the inorganic thin film transparent film covering the surface with the colored layer containing the organic resin film as the base, especially the base of the inorganic thin film. It tends to occur easily starting from minute irregularities of the organic layer. It is also possible to reduce cracks to some extent by relaxing the internal stress of the film as much as possible depending on the film forming conditions of the thin film forming process such as sputtering or vacuum deposition for forming a transparent conductive film. However, it is difficult to select conditions that achieve both excellent electro-optical characteristics of the transparent electrode layer and complete prevention of cracks.

  In addition to the above-described morphological factors such as surface irregularities, as a factor for generating cracks in the transparent conductive film 4 on the pixel boundary portion, during the transparent conductive film formation process or after the formation of the transparent conductive film During processing steps such as heat treatment, shrinkage due to heat received by the resin constituting the colored transparent pixels of the base can be considered. In particular, when the content of the resin having a high thermal contraction rate is large, the stress exerted on the transparent conductive film from the base is increased. Furthermore, at the pixel border where the two color pixel edges made of different materials overlap or are adjacent to each other, the morphological factors combined with the factors associated with the heat shrinkage change generate the most cracks in the transparent conductive film. It will be easy to do.

3A and 3B are schematic views for explaining the configuration of the color filter of the present invention in more detail before the transparent conductive film is formed, in which FIG. 3A is an enlarged plan view, and FIG. 3B is a dotted line in FIG. It is sectional drawing which further enlargedly displayed the inside of the circle.
As shown in FIG. 3A, among the pixel boundaries defined by the black matrix 2, colored transparent pixels 3r formed in stripes of red, green, and blue on the vertical BM in the drawing. Each edge of the 3g and 3b columns constitutes a pixel boundary where two different pixel edges overlap or are adjacent. When the pixel boundary is not defined by the BM, an overlapping portion or an adjacent region of the pixel edge substantially corresponding to the BM width is defined as the pixel boundary.

  Further, in this example, the overlapping portion 8 of the colored transparent pixels shown in FIG. 3B is overlapped with the edge of the red pixel 3r and the edge of the green pixel 3g on the black matrix 2 on the substrate 1. A minute concave portion 9 indicated by a lead line is formed. As described above, since the concave portion 9 is the place where the crack is most likely to occur in the transparent conductive film, the overcoat layer 5 is formed of the same material as the blue pixel 3b.

Next, a method for producing the color filter of the present invention will be described.
As the substrate 1, a transparent substrate such as non-alkali glass used in a general liquid crystal display device can be used. When the BM pattern is formed by the above-described photolithography method, for example, titanium black 12S manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd. can be used as a light-shielding pigment. Among the materials used when the colored transparent pixels are formed by the photolithography method described above, examples of the pigment of each color include C.I. I. Pigment Red 254, and C.I. I. Pigment Red 177, as a green pigment, C.I. I. Pigment Green 36, and C.I. I. Pigment Yellow 150, as a blue pigment, C.I. I. Pigment Blue 15, and C.I. I. Pigment Violet 23 can be used.

  A varnish containing an acrylic resin is added to the color pigments of each color to prepare a dispersion of each color, and then a photocurable monomer, a photopolymerization initiator, a sensitizer, and a solvent are added as appropriate, and mixed and filtered uniformly. A photosensitive coloring material for coating is obtained. The red pixel 3r for the first color is formed at a predetermined position by means of ordinary photolithography, and the same means is repeated to form the green pixel 3g for the second color at a predetermined position adjacent to the red pixel 3r. When forming the third color, the blue pixel 3b of the third color is formed at a predetermined position between the red pixel 3r and the green pixel 3g, and at the same time, the overcoat layer 5 is formed between the red pixel and the green pixel in the same process. It is formed on the pixel boundary. In the case of using the photo-curable photosensitive material of this example, the openings of the photomask used in the exposure process are provided in a region corresponding to the blue pixel 3b and a region corresponding to the overcoat layer 5. Simultaneous formation is possible. That is, it is possible to take measures to prevent cracks in the transparent conductive film without increasing any load on the process.

  Next, as the final step of manufacturing the color filter, an ITO transparent conductive film is uniformly sputtered to a thickness of about 100 nm on the clean surface of the color filter on which the black matrix and the colored transparent pixel pattern are formed. Can do.

  In this example, the overcoat layer 5 is provided only on the pixel boundary portion between the red pixel 3r and the green pixel 3g and is not provided on another type of pixel boundary portion. It does not prevent the overcoat layer from being provided on the pixel boundary between the pixel 3g and the blue pixel 3b or on the pixel boundary between the blue pixel 3b and the red pixel 3r. However, in the case of providing on a plurality of kinds of pixel boundary portions, it is inevitable that the manufacturing process becomes complicated.

  On the other hand, in this example, an overcoat layer made of a blue material of the third color, which is convenient in the order of formation of the colored transparent pixels, is formed, and the blue material has a resin ratio in the dispersion dispersed in other colored materials. Since it can be made lower than the body, it can be produced with a relatively small thermal shrinkage. For this reason, providing the overcoat layer 5 with the same material as that of the blue pixel 3b on the pixel boundary portion between the red pixel 3r and the green pixel 3g can provide the most effective countermeasure.

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Black matrix 3r ... Red pixel 3g ... Green pixel 3b ... Blue pixel 4 ... Transparent conductive film 5 ... Overcoat layer 8 ... Colored transparent pixel Overlapping part 9 ... concave part

Claims (4)

  A color filter in which colored transparent pixels of a single color are arranged in a color by regularly repeating three or more colors on a substrate, and a transparent conductive film is provided so as to cover the entire surface of the color arrangement region. An overcoat layer made of a colored transparent pixel material having a color different from the two colors constituting the pixel boundary portion is provided under the transparent conductive film, limited to the pixel boundary portion where the pixel edge portions overlap or are adjacent to each other. Color filter.   The color filter according to claim 1, wherein the pixel boundary part is defined in advance by a black matrix pattern as a light-shielding base of the pixel edge part.   The color arrangement of the colored transparent pixels is composed of three colors of red, green, and blue, and the overcoat layer is formed of a blue material on a pixel boundary portion between the red pixel and the green pixel. Or the color filter of 2.   After the colored transparent pixels are patterned in the order of red and green by photolithography, when forming the blue pixels, simultaneously with the formation of the blue pixels, an overcoat layer made of the same material is formed on the pixel boundary between the red and green pixels. The method for producing a color filter according to claim 1, wherein the color filter is formed by photolithography.