Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified...
Reexamination Certificate
1999-08-09
2001-08-14
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
C252S299010, C252S299630, C252S299660, C252S299670, C349S035000, C349S169000
Reexamination Certificate
active
06274208
ABSTRACT:
This application is based on application No. 10-231923 filed in Japan, the contents of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal composition which exhibits a cholesteric phase at room temperature and a bistable/reflective type liquid crystal display device provided with the liquid crystal composition.
2. Description of Related Art
Recently, studies have been made to develop reflective liquid crystal displays by using chiral nematic liquid crystal which is produced by adding a chiral agent to nematic liquid crystal to cause the liquid crystal to exhibit a cholesteric phase at room temperature. Such a liquid crystal display operates by switching between a planar state and a focal-conic state in accordance with the level of the pulse voltage applied thereto. The planar state and the focal-conic state can be maintained after the application of the pulse voltage (which is referred to as bistability or non-volatility), whereby the display can be maintained even after stoppage of the application of the voltage.
At present, however, in such a reflective liquid crystal display, the reflectance is low, and the contrast between the planar state and the focal-conic state is not sufficiently high, and liquid crystal displays of this type which are satisfactory in performance such as color purity (excitation purity), etc. are yet to be developed. To this type of liquid crystal displays, it is also important to have a wide temperature compensation range.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a liquid crystal composition which, when used for a liquid crystal display device, has good bistability, color purity, reflectance, etc. and has high contrast.
Another object of the present invention is to provide a liquid crystal composition which, when used for a liquid crystal display device, has a wide temperature compensation range.
Another object of the present invention is to provide a liquid crystal display device which has good bistability, color purity, reflectance, etc. and has high contrast.
Further, another object of the present invention is to provide a liquid crystal display device which has a wide temperature compensation range.
In order to attain the objects, a liquid crystal composition according to the present invention is a chiral nematic liquid crystal composition which contains a liquid crystal tolan compound, a liquid crystal ester compound, a liquid crystal phenylcyclohexane compound and a chiral agent.
Also, a liquid crystal display device according to the present invention comprises a pair of substrates, at least one of which is transparent, the above mentioned liquid crystal composition provided between the substrates, and a device for applying an electric field to the liquid crystal composition.
By using the liquid crystal composition, the characteristics such as color purity, reflectance, etc. can be improved, and a display with high contrast becomes possible. Also, if a plurality of chiral agents are contained in the liquid crystal composition, the temperature compensation range can be widened.
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Caplus 1995: 498303.
Iwamatsu Masako
Kobayashi Nobuyuki
Ueda Hideaki
Minolta Co. , Ltd.
Sidley & Austin
Wu Shean C.
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