Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Optical excitation
Reexamination Certificate
1998-01-07
2001-05-15
Sikes, William L. (Department: 2515)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Optical excitation
C349S133000
Reexamination Certificate
active
06233027
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a liquid crystal device suitably used in a photo-writing type device for writing data therein by light illumination, and a process for producing such a liquid crystal device.
Hitherto, there has been proposed a photo-writing type liquid crystal device or a space light modulation for writing data therein by light illumination (hereinafter inclusively called an “SLM”).
The SLM is a kind of liquid crystal device including a photoelectric conversion semiconductor layer and a liquid crystal layer and designed for writing data by illumination with writing light and reading data by illumination with readout light.
The SLM may be classified into a transmission-type one to be illuminated with readout light incident thereto from a side opposite to an observer, and a reflection-type one to be illuminated with readout light incident thereto from the side of an observer.
A transmission-type SLM is reported in Journal of Photopolymer Science and Technology, Volume 5, Number 2, 1992, pp. 397-405 and Japanese Laid-Open Patent Application (JP-A) 3-275723.
As shown in
FIG. 1
, such an SLM
1
includes a pair of transparent glass substrates
2
and
3
disposed with a prescribed gap therebetween and having transparent electrodes
5
and
6
, respectively, of ITO (indium-tin oxide) on their inner surfaces. Further, one transparent electrode
5
is coated with a 2 &mgr;m-thick photoconductive polymer film
7
as a photoelectric conversion semiconductor layer, and the other transparent electrode
6
is coated with an alignment film
12
. These substrates
2
and
3
are applied to each other with a sealant (not shown), and the gap therebetween is filled with a ferroelectric liquid crystal
9
.
The above-mentioned photoconductive polymer film
7
and alignment film
12
both have been subjected to a rubbing treatment and a heat treatment at a temperature and a heat treatment at a temperature around 300° C. for crystallization.
In the SLM shown in
FIG. 1
, the photoconductive polymer film
7
is formed from a polyimide film forming a uniaxial alignment film through rubbing and heat treatment, so that additives, such as a charge generation substance and a charge transportation substance, have to be selected in consideration of their heat resistance and chemical resistance. Accordingly, the latitude of selection of these additives is narrow so that the sensitivity thereof are liable to be lower. Further, in case of using a chiral smectic liquid crystal having a bookshelf layer structure capable of providing a high contrast, alignment defects are liable to occur.
As a liquid crystal device different from an SLM and having no photoelectric conversion semiconductor layer, there has been known a type of display devices comprising a plurality of scanning electrodes and a plurality of data electrodes arranged so as to form an electrode matrix for multiplexing drive.
Among such liquid crystal display devices, a display device using a chiral smectic liquid crystal is promising as a high resolution display device but has been known to require a difficult technique for alignment of liquid crystal molecules without alignment defects. Particularly, a sophisticated technique is required for aligning a chiral smectic liquid crystal into a bookshelf layer structure, e.g., as disposed in U.S. application Ser. No. 08/509,929 filed on Aug. 1, 1995 and entitled “Liquid Crystal Device” (or EP-A 0695965). However, the alignment technique still cannot be said as a sufficient process for providing a liquid crystal display device having a bookshelf layer structure at a low cost and a good reproducibility. The remaining problems may include: obtaining a bookshelf layer structure free from alignment defects, obtaining good liquid crystal injection performance, and suppressing a thermal distribution generated by flowing drive currents.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a liquid crystal device allowing a simple and inexpensive production process.
Another object of the present invention is to provide a liquid crystal device having good display quality through suppression of deterioration of display performance due to temperature change and with good alignment state.
Another object of the present invention is to provide a liquid crystal device of photo-writing type having a good sensitivity.
A further object of the present invention is to provide a liquid crystal device of photo-writing type having a good light transmissivity.
According to the present invention, there is provided a liquid crystal device comprising a pair of substrates each having a liquid crystal-contacting layer thereon, and a liquid crystal disposed between the pair of substrates, one of the liquid crystal-contacting layers comprising a photoelectric conversion semiconductor layer free from a uniaxial alignment characteristic, and the other of the liquid crystal-contacting layers comprising a uniaxial alignment film.
In a preferred embodiment, the liquid crystal comprises a chiral smectic liquid crystal aligned to assume a bookshelf layer structure.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
REFERENCES:
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patent: 5128228 (1992-07-01), Ueda et al.
patent: 5153761 (1992-10-01), Marlor
patent: 5338632 (1994-08-01), Hashimoto et al.
patent: 5666217 (1997-09-01), Kaneko et al.
patent: 5686019 (1997-11-01), Nakamura
patent: 5731797 (1998-03-01), Akiyama et al.
patent: 5786118 (1998-07-01), Terrell et al.
patent: 5825447 (1998-10-01), Hanyu et al.
patent: 6031655 (2000-02-01), Yagyu
patent: 695965 (1996-02-01), None
patent: 59-216126 (1984-12-01), None
patent: 03275723 (1991-12-01), None
Journal of Photopolymer Science and Technology, vol. 5, No. 2 (1992), pp. 397-405.
Journal of Nippon Settsuyaki Kyokai, vol. 8, No. 3 (1972), p. 131.
Hashimoto Yuichi
Unno Akira
Yagyu Mineto
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Nguyen Dung
Sikes William L.
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