Optical: systems and elements – Optical computing without diffraction
Patent
1992-10-05
1994-07-19
Sikes, William L.
Optical: systems and elements
Optical computing without diffraction
359 38, 359 70, G02F 113
Patent
active
053314484
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device which can be used, for example, for a TV screen, various office automation instruments and other display panels, a process for preparing the same and use of the same, for example, as a variable traffic control sign, a light-adjusting window and a liquid crystal glare-proof mirror.
DESCRIPTION OF THE PRIOR ART
Hitherto, a liquid crystal display device has been formed by injecting a liquid crystal material between a pair of transparent electrodes which are fixed with a gap of several micrometers. However, such structure does not enable the production of the display having a large area. In addition, brightness of the screen and an angle of view field are insufficient, since it is necessary to attach polarization plates having polarization axes which are perpendicular to each other to a pair of glass substrates enclosing the liquid crystal material.
In addition, in the conventional liquid crystal display device except one using a ferroelectric liquid crystal, an orientated state has no memory so that an active matrix driving such as TFT which is produced in a low yield should be used to produce a display screen having a large number of picture elements. Therefore, the production cost increases. When the ferroelectric liquid crystal is used, a very thin cell gap control of 1 to 2 .mu.m and a uniform orientation of liquid crystal molecules are necessary, so that the ferroelectric liquid crystal cannot provide a satisfactory display even in a small area.
Recently, a new liquid crystal display device has been developed (cf. Japanese Patent Kokai Publication Nos. 193115/1990 and 127494/1990, Chem. Lett., 817 (1989) and Polymer Preprints, Japan, 39 (8), 2373 (1990)). This device is prepared by cast coating a solution of a side chain type liquid crystalline polymer having a side chain to which a moiety corresponding to a liquid crystal compound is bonded and a conventional low molecular weight liquid crystal in a solvent on a plate-form support or a film such as a transparent electrode, drying and solidifying the solution to form a mixture film of the liquid crystalline polymer and the low molecular weight liquid crystal and placing another support thereon.
In the above liquid crystal display device, when a low frequency or a direct current is applied on the mixture film, ions move in accordance with an electric field in the mixture film so that the orientation of the liquid crystal molecules is disturbed to strongly scatter an incident light and the film becomes opaque. When a high frequency is applied on the mixture film of the liquid crystalline polymer and the low molecular weight liquid crystal, the liquid crystal molecules in the film are homeotropically orientated by the electro-optic effect in a direction of an electric field, so that the incident light passes through the film without being scattered and the film becomes transparent. In this liquid crystal display device, after the electric field is removed, the display device has memory and maintains scattered or non-scattered states of light stably.
In the conventional mixture film of the liquid crystalline polymer and the low molecular weight liquid crystal, since a single low molecular weight liquid crystal is used, a temperature range of the smectic phase which exhibits the memory is narrow and it does not function at room temperature. Polym. Preprints, Japan, 39 (8), 2373 (1990) discloses a system comprising two low molecular weight liquid crystals. A function of one of the two low molecular weight liquid crystals is to replace the mesogen groups of the liquid crystalline polymer.
The change from the transparent state to the opaque state of the above mixture film is caused by the movement of the ions which present in a slight amount in the mixture film in accordance with the direct current or low frequency field. But, a response speed of this change is low so that stability and reproducibility of the response to the application of the electric field are poor.
One
REFERENCES:
patent: 4822143 (1989-04-01), Zondler
patent: 5034153 (1991-07-01), Uchida
F. Schneider and N. K. Sharma, Influence of the Amino Substituent on the Induction of Smectic Phases, Aug. 13, 1981, A. Naturforsch, 30n, 1086-1091 (1981).
Hara Kouji
Kajiyama Tisato
Kashiwagi Tohru
Ono Junichi
Takata Kensaku
Mai Huy
Sikes William L.
Sumitomo Electric Industries Ltd.
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