Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-08-27
2004-09-28
Ngo, Huyen (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S106000, C349S139000
Reexamination Certificate
active
06798486
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device, and particularly to a liquid crystal display device provided with spacers sandwiched between a pair of opposing substrates with a liquid crystal layer interposed therebetween.
Placement of spacers between a pair of opposing substrates with a liquid crystal layer therebetween can establish a uniform thickness of the liquid crystal layer and thereby prevent occurrence of non-uniformity in a displayed image.
Beads, for example, are used as spacers. Initially beads are dispersed on a surface of one of a pair of substrates facing toward a liquid crystal layer, and then the other of the pair of substrates is overlapped over the one of the pair. But the surfaces of the substrates are uneven, some spacers are positioned in indented portions in the surfaces of the substrates, others are positioned in raised portions in the surfaces in the substrates, and consequently, the desired spacing between the pair of substrates are not sometimes obtained.
There is another type of spacers which are fixed at predetermined positions on a surface of one of a pair of substrates facing toward a liquid crystal layer before the other of the pair of substrates is overlapped over the one of the pair. The spacers are formed only on indented portions in the uneven substrate, for example, and consequently, the desired spacing between the pair of substrates is obtained.
Spacers are disclosed in Japanese Patent Application Laid-open No. Hei 8-76131 (laid-open on Mar. 22, 1996), Japanese Patent Application Laid-open No. Hei 8-114809 (laid-open on May 7, 1996) and Japanese Patent No. 2,907,137 (registered on Apr. 2, 1999).
SUMMARY OF THE INVENTION
The spacers of the above-explained type having the spacers fixed on a substrate have the above advantage and can also improve the display quality further by optimizing the arrangement of the spacers.
The present invention has been made in this situation, and the purpose of the present invention is to provide a liquid crystal display device having the quality of a displayed image improved.
The representative ones of the inventions disclosed in this specification can be summarized as follows.
To accomplish the above object, in accordance with an embodiment of the present invention, there is provided a liquid crystal display device comprising: a pair of opposing substrates, at least one of said pair of opposing substrates being transparent, a liquid crystal film sandwiched between said pair of opposing substrates, a plurality of electrodes of a first kind disposed on an inner surface of one of said pair of opposing substrates for defining a plurality of pixels, at least one electrode of a second kind disposed on an inner surface of one of (1) said one of said pair of opposing substrates so as to be adjacent to, but spaced from said plurality of electrodes of said first kind and (2) another of said pair of opposing substrates so as to face said plurality of electrodes of said first kind, and at least one spacer disposed approximately at a center of at least one of said plurality of pixels for establishing a spacing between said pair of opposing substrates, said at least one spacer being fixed to one of said pair of opposing substrates and covered with one of (1) a corresponding one of said plurality of electrodes of said first kind and (2) a corresponding one of said at least one electrode of said second kind.
To accomplish the above object, in accordance with another embodiment of the present invention, there is provided a liquid crystal display device comprising: a pair of opposing substrates, at least one of said pair of opposing substrates being transparent, a liquid crystal film sandwiched between said pair of opposing substrates, a plurality of electrodes of a first kind disposed on an inner surface of one of said pair of opposing substrates for defining a plurality of pixels, at least one electrode of a second kind disposed on an inner surface of one of (1) said one of said pair of opposing substrates so as to be adjacent to, but spaced from said plurality of electrodes of said first kind and (2) another of said pair of opposing substrates so as to face said plurality of electrodes of said first kind, and at least one spacer disposed approximately at a center of at least one of said plurality of pixels for establishing a spacing between said pair of opposing substrates, said at least one spacer being fixed to one of said pair of opposing substrates and covered with one of (1) a corresponding one of said plurality of electrodes of said first kind and (2) a corresponding one of said at least one electrode of said second kind, and another of said corresponding one of said plurality of electrodes of said first kind and said corresponding one of said at least one electrode of said second kind being patterned so as not to face said at least one spacer.
To accomplish the above object, in accordance with still an embodiment of the present invention, there is provided a liquid crystal display device comprising: a pair of opposing substrates, at least one of said pair of opposing substrates being transparent, a liquid crystal film sandwiched between said pair of opposing substrates, a plurality of electrodes of a first kind disposed on an inner surface of one of said pair of opposing substrates for defining a plurality of pixels, a plurality of wiring lines of a first kind coupled to said plurality of electrodes of said first kind, at least one electrode of a second kind disposed on an inner surface of one of (1) said one of said pair of opposing substrates so as to be adjacent to, but spaced from said plurality of electrodes of said first kind and (2) another of said pair of opposing substrates so as to face said plurality of electrodes of said first kind, at least one wiring line of a second kind coupled to said at least one electrode of said second kind, and at least one spacer disposed approximately at a center of at least one of said plurality of pixels for establishing a spacing between said pair of opposing substrates, said at least one spacer being fixed to one of said pair of opposing substrates and covered with one of (1) a corresponding one of said plurality of electrodes of said first kind and (2) a corresponding one of said at least one electrode of said second kind, and said at least one spacer being disposed so as to face one of (1) said plurality of wiring lines of said first kind and (2) said at least one wiring line of said second kind.
In the liquid crystal display device employing a spacer covered with an electrode, directions of electric fields generated between the side wall of the spacer and another electrode are different from directions of electric fields generated by the electrode and the another electrode in the remaining region of one pixel associated with the spacer, and consequently, the so-called “multi-domain” effect is produced in the region in the vicinity of the side wall. The reversal in transmitted light intensity through the liquid crystal layer occurs at viewing angles deviating considerably from the main anticipated viewing angle due to the angular dependence of the electro-optic characteristics of the liquid crystal layer. The so-called multi-domain effect is that obtained by subdividing one pixel into a plurality of regions provided with different angular dependence of the electro-optic characteristics to reduce the angular dependence of the one pixel as a whole and thereby to eliminate or reduce the above-mentioned reversal in transmitted light intensity.
And in the liquid crystal display device of the horizontal electric field type described subsequently, the optimum arrangement of spacers is secured.
REFERENCES:
patent: 5949511 (1999-09-01), Park
patent: 6097467 (2000-08-01), Fujimaki et al.
patent: 6211937 (2001-04-01), Miyachi et al.
patent: 6317188 (2001-11-01), Shibahara
patent: 6411360 (2002-06-01), Matsuyama et al.
patent: 08076131 (1996-03-01), None
patent: 08114809 (1996-05-01), None
patent: 10048636 (1998-02-01), None
Ashizawa Keiichiro
Hikiba Masayuki
Ishii Masahiro
Yanagawa Kazuhiko
A. Marquez, Esq. Juan Carlos
Fisher Esq. Stanley P.
Hitachi , Ltd.
Ngo Huyen
Reed Smith LLP
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