Compositions – Light transmission modifying compositions – Inorganic crystalline solid
Patent
1994-06-09
1996-04-30
Tucker, Philip
Compositions
Light transmission modifying compositions
Inorganic crystalline solid
252582, 427162, 427164, G02B 520, B05D 506
Patent
active
055122159
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a shading film for a black matrix for a color filter used in colored liquid crystal display devices, electroluminescence displays, colored fluorescent display devices, plasma display panels, operation analysis (OA) sensors, solid-state image sensors, and the like, and, to a coating for forming a shading pattern film.
BACKGROUND ART
A liquid crystal display device is provided with a color filter of a structure whereby, for example, picture elements of the colors red, green, and blue, which are three of the basic colors of light (hereinafter RGB color picture elements) are arranged systematically on a transparent substrate of a material such as glass, plastic, or the like.
The picture elements of a color filter are formed by means of a dyeing method in which a resin layer on which patterns have been formed using a photolithography method is dyed; a colored resist method whereby patterns are formed using a photolithography method on a previously colored plastic; a silver chloride photographic method for developing color in a silver chloride photograph; an electrodeposition method for forming patterns by electrophoresis of a coloring material; or an interference film method for forming patterns of a multilayered interference film. In addition, these picture elements can also be formed by methods wherein the above-mentioned methods are combined.
One criterion which can be given as for the image quality of a color filter for the above-mentioned type of liquid crystal display device is the contrast ratio. The contrast ratio is obtained by comparing the brilliance of a picture element dot onto which no beam is shone with the brilliance of a picture element dot onto which a beam is shone, and expressing the result as a ratio. The larger the contrast ratio of a picture, the better the picture quality. Another criterion is the variation in the spectral diffraction as discussed in Japanese Laid-Open Patent No.62-280806. In this case, the smaller the variation in the spectral diffraction, the better the image quality.
In order to increase the above-mentioned contrast ratio for the color filter, a method is known whereby a shading pattern film (black matrix) 2 is formed on the part of the picture on which no picture elements are formed, specifically, on the periphery of each of a plurality of picture elements 3 on a substrate 1, so that leakage of light is prevented, and the brilliance is reduced when no beam is shone on a picture element dot, as shown in FIG. 1.
For this type of shading pattern film, a thin film is formed on a substrate by means of a vapor deposition method, sputtering, or an ion plating method, using a metal such as chromium, aluminum, tantalum, or the like, or using a metallic oxide of copper oxide or the like. Then, the thin film is formed into the pattern film by selective removal in accordance with a photo-etching method. Or, the thin film is formed by an application in accordance with a photolithography method, a printing method, an electrodeposition method, or the like, using a coating which is a mixture of a black dye or pigment with a resin. The performance of the black matrix is evaluated by means of the reflection and shading characteristics and the like of the shading film. The shading characteristics can be illustrated by means of the optical density (extinction) value. An optical density=1 means that 10% of the incident light is passed through; an optical density=2 means that 1% of the incident light is passed through; and an optical density=3 means that 0.1% of the incident light is passed through. Specifically, the larger the numerical value of the optical density, the better the shading characteristics.
Of the conventional methods of forming the black matrix described above, in the method whereby a thin film is formed on a substrate by means of a vapor deposition method, sputtering, or an ion plating method, using a metal or a metallic oxide and then etched, a substrate for the color filter is placed in a vacuum system. For this reas
REFERENCES:
patent: 3734728 (1973-05-01), Kachel
patent: 5387573 (1995-02-01), Oldfield et al.
Kobayashi, Syunsuke, "Color Liquid Crystal Display", Display Technology Series, published by Sangyo Tosho, (1992).
Gakkai, Nihon Shikisai, Color Science Handbook, Japanese Society of Color Science, published by Tokyo Daigaku Syuppankai, (1980).
Aoki Minoru
Chiyoda Hironobu
Kotera Shigeo
Tachizono Shinichi
Takashima Shigeo
Hitachi Powdered Metals Co. Ltd.
Tucker Philip
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