Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-07-19
2001-03-27
Dudek, James A. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S156000
Reexamination Certificate
active
06208401
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal panel and a method for producing the same and, more particularly to a liquid crystal panel which is produced by lithography and electro-deposition and a method for producing the same.
2. Description of the Related Art
Personal computers and monitors prevail in recent years because of the rapid development of information and multimedia. A liquid crystal display (LCD), as a solution of reducing environmental pollution, has been proposed to replace a display tube as a main display device. Therefore, it is required that LCD should be as high display quality as the display tube is. However, there are lots of problems to be overcome in reaching the goal.
A liquid crystal panel, especially color one shown in
FIG. 1
, includes a color filter substrate
10
, a liquid crystal driving substrate
8
, and a liquid crystal material
9
in cells within the gap between the color filter substrate
10
and the liquid crystal driving substrate
8
. The cell gap, usually from several microns to dozens of microns in length, is formed by spacers
7
. Conventionally, the spacers are plastic or glass pellets distributed on a second conductive film
2
′. It is hard to distribute the pellets uniformly in this method, and thus nonuniform cell gap and poor display quality arise, especially in large scale display panels. Furthermore, the light is subject to scattering and thus inducing a poor contrast because the pellets may be distributed on a red filter
4
, a green filter
5
and a blue filter
6
. Still, the pellets will move in cells while the liquid crystal material
9
is filled, and will disconnect driving wires.
U.S. Pat. No. 4,874,461 discloses a liquid display panel in which the spacers are produced by photolithographic process. The spacers are easy to shed since photocure process incompleteness may occur in production, and uniformity in size is poor. Japanese Patent Publication No. HEI-6-222370 discloses stripy stria spacers. The resolution is poor because of utilizing negative photoresist and the spacer patterns are limited.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a liquid crystal panel in which the thickness and uniformity of the spacer are easy to control and small cell gap and excellent display quality could be obtained.
Another object of the present invention is to provide a liquid crystal panel in which no spacer is placed on effective display filters and display quality can be improved.
A further object of the present invention is to provide a process for producing a liquid crystal panel in which the thickness and uniformity of spacers can be effectively controlled. A small and uniform cell gap could be obtained.
Another further object of the present invention is to provide a process for producing a liquid crystal panel in which spacers are all positioned on a black matrix rather than effective display filters.
A still further object of the present invention is to provide an improved process for producing a liquid crystal panel. The process improves the product yield and display quality, and can be applied in large-scale LCDs.
To achieve the above objects, the present invention discloses a liquid crystal panel, comprising a liquid crystal driving substrate, a color filter substrate disposed under the liquid crystal driving substrate, a liquid crystal material disposed between the liquid crystal driving substrate and the color filter substrate and a plurality of spacers; in which the color filter substrate comprises a glassy substrate, a first conductive film disposed on the glassy substrate, color filters, a black matrix and a second conductive film disposed on the color filters; and characterized in that each color filter is compartmentalized by the black matrix, the spacers are positioned on the region confined by the black matrix, and the bottom of the spacer contacts the first conductive film. In preferred embodiments of the invention, the spacers are polymeric compositions and made by electro-deposition and the thickness of the spacer is controlled by electro-deposition. The spacers are light or thermal hardened resins which are black or opaque. Alternatively, the spacers are light or thermal hardened resins which are transparent or colored.
To achieve the above objects, the present invention discloses a process for producing a liquid crystal panel, comprising producing a liquid crystal driving substrate, a color filter substrate disposed under the liquid crystal driving substrate, a liquid crystal material disposed between the liquid crystal driving substrate, and the color filter substrate, and a plurality of spacers; wherein the process of producing the color filter substrate comprising the step of producing a glassy substrate, a first conductive film disposed on the glassy substrate, color filters, a black matrix, and a second conductive film disposed on the color filters; and characterized in that the color filters and spacers are produced by: coating four-level photoresist on the first conductive film, exposing the photoresist for the first time with four-level photoresist, producing the red, green and blue regions by repetitive development and electro-deposition, exposing the photoresist for the second time with a spacer reticle, revealing the first conductive film within a region confined by the black matrix by development, and electrodeposition coating compositions on the revealed first conductive film. In another embodiment of the invention, the electro-deposition compositions are light or thermal hardened resins which are black or opaque, or are light or thermal hardened resins which are transparent or colored. The position and size of the spacer are determined by the spacer reticle and the spacer thickness of the spacer is controlled by electrodeposition conditions coating compositions for producing the spacers. The four-level photoresist is positively photosensitive resin.
REFERENCES:
patent: 4874461 (1989-10-01), Sato et al.
patent: 6002462 (1999-12-01), Sato et al.
patent: 1-94320 (1989-04-01), None
patent: 6-222370 (1994-08-01), None
patent: 10-48643 (1998-02-01), None
Chan Ming-Hsiang
Cheng Hua-Chi
Cheng Shu-Huei
Kuwahara Hajime
Wen Chun-Hsiang
Alston & Bird LLP
Dudek James A.
Industrial Technology Research Institute
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