Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Patent
1996-02-21
1999-03-09
Sikes, William L.
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
G02F 11333
Patent
active
058807993
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a resin black matrix for color filters used in liquid crystal display devices, and more specifically relates to a resin black matrix for color filters that has high displaying characteristics.
BACKGROUND OF THE INVENTION
Generally, a color filter for liquid crystal display consists of a large number of color triplets, each made up of three color pixels (red, green, and blue), formed on a transparent substrate. To enhance the contrast of the display, these pixels are distributed with specific intervals over a light-shielding region, which is called the black matrix because of its color on the screen.
Most of the conventional color filters use a black matrix produced by the photolithography, and comprise a thin metal film with a fine pattern. The metals used for such black matrices include Cr, Ni, and Al, and the methods used for producing them include such vacuum film forming methods as sputtering and vacuum deposition. To form a fine pattern, the photolithography is used in most cases to form a pattern on photoresist, and this photoresist pattern is then used as etching mask to etch thin metal film. The thin metal film produced by this process has the same fine pattern as that on the photoresist.
The methods for producing pixels include the dyeing of a dyeable medium formed by the photolithography, the use of a photosensitive composition consisting of dispersed pigment, the etching of non-photosensitive composition consisting of dispersed pigment, and the electrodeposition of pigment onto a patterned electrode, as well as such low-cost methods as the formation of colored portions by ink jet or other printers.
SUMMARY OF THE INVENTION
However, a black matrix made of thin metal film requires large costs for the thin metal film forming process, which is responsible for the high prices of color filters. In addition, chrome, which is generally used in thin metal film for black matrices, is high in reflectance, leading to strong reflection from the chrome plane in places where strong light comes in from the surroundings. In particular, the displaying performance may be largely reduced if a color filter is used with a transmission type display device. A method has been proposed wherein a layer of such material as chrome oxide is provided between the chrome layer and the transparent substrate with the aim of reducing the reflectance of the black matrix. This, however, further increases the cost for the black matrix production, and cannot serve for price reduction.
To solve this problem, other methods have been proposed wherein, for example, a black matrix is formed by patterning resin that is colored with a light shading material, followed by the formation of color pixels to produce a color filter. Carbon black, which has good light-shading properties, is generally used as such a light shading material, but it has not been possible to achieve a sufficiently high light-shading performance as compared with thin metal film. As a result, part of the backlight may pass the black matrix and reach the display surface. In addition, the transmitted light from carbon black has a color, and when such colored light reaches the display surface, it will be impossible to show the intended colors, particularly for black or other low-brightness colors. The light shading performance can be enhanced by increasing the thickness of the black matrix, but this will reduce the flatness of the surface, leading to other problems of picture quality deterioration.
The present invention was made in view of these problems and with the object of providing a highly light shading black matrix with achromatic characteristics.
This object of the invention is met by using such a black matrix for liquid crystal display device as described below. Specifically, the invention relates to a resin black matrix for liquid crystal display device wherein the black matrix for liquid crystal display device contains dispersed light shading agents, wherein the chromaticity coordinates (x, y) in the XYZ color
REFERENCES:
IBM Technical Disclosure Bulletin, vol. 34, No. 4A, 1 Sep. 1991, pp:122-123, XP000210850 "Black Matrix for LCDS," the whole document.
Database WPI Section Ch. Week 9212, Derwent Publications Ltd., London, GB; Class A26, AN 92-094155, XP002029603 & JP 04 040 420 A (Seiko Epson Corp), 10 Feb. 1992, abstract.
Patent Abstracts of Japan, vol. 11, No. 49 (P-547) & JP 61 215525 A (Matsushita) Abstract.
Goto Tetsuya
Inoue Keijiro
Tomita Fumio
Dudek James A.
Sikes William L.
Toray Industries Inc.
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