Liquid crystal cells – elements and systems – Cell containing liquid crystal of specific composition
Reexamination Certificate
2001-04-06
2004-10-05
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Cell containing liquid crystal of specific composition
C428S001100
Reexamination Certificate
active
06801292
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a liquid crystal device for use in a flat panel display, a paper display, a projection display, a light valve for printer, etc.; a liquid crystal composition for use in the liquid crystal device; and a liquid crystal apparatus including the liquid crystal device. The present invention further relates to a phase compensation plate, a viewing angle compensation plate, a liquid crystal switching device, an active-type liquid crystal device, and a liquid crystal apparatus using the liquid crystal device.
CRTs (cathode ray tubes) have been extensively used as most popular display devices, for motion picture display for television and video tape recorder, and monitors for personal computers. Based on the operation characteristic, however, a CRT is accompanied with difficulties such that the recognizability of a static picture is lowered due to flicker and scanning fringes caused by an insufficient resolution, and the fluorescent screen thereof is deteriorated due to burning or sticking. Other problems of the CRT are possible adverse effect of electromagnetic wave emitted therefrom and large power consumption. Further, the CRT structurally has a large rearward volume behind the display surface, thus restricting the facility of information apparatus including the CRT and being unsuitable for space economization in office or home use.
As a type of device solving such problems of the CRT, there has been known a liquid crystal display device including a type using a twisted nematic (TN)-mode liquid crystal as disclosed by M. Schadt and W. Helfrich, “Applied Physics Letters”, Vol. 18, No. 4 (Feb. 15, 1971), pp. 127-128. There are also known other liquid crystal device modes, inclusive of in-plane switching mode (IPS), multi-domain vertical alignment mode (MVA), and high-speed switching modes using a smectic liquid crystal, such as ferroelectric liquid crystal (FLC) or anti-ferroelectric liquid crystal (AFLC).
In recent years, as a type of liquid crystal device, TFT-liquid crystal devices have been developed and commercialized. The TFT-liquid crystal device includes a matrix of pixels each provided with a TFT (thin-film transistor) for solving the problem of crosstalk and is produced in display sizes of 10-13 inches at a good productivity owing to a rapid progress in production technology. However, the TFT-liquid crystal device has left problems in production of a larger size panel with a good viewing angle characteristic and in response speed for allowing a frame frequency of 60 Hz or higher desired for satisfactory motion picture reproduction
These technical problems involved in liquid crystal devices are attributable to viscoelasticities and optical birefringence characteristic of known liquid crystal materials, and there are incessant desires for novel liquid crystal materials, and alignment states thereof, and novel switching modes of liquid crystal devices.
As another problem to be considered, the above-mentioned conventional liquid crystal devices are ordinarily used as a display panel in combination with a backlight (device) by optically modulating a transmitted light passing through the liquid crystal device. Accordingly, the backlight for the liquid crystal device is required to emit a strong light. Further, a consumption power of liquid crystal display apparatus is largely occupied by the backlight. Even when a lithium ion-secondary battery is used for such a liquid crystal display apparatus, a continuous (successive) operation time for, e.g., mobile computing is approximately several hours at the best. Thus, if backlight devices for various liquid crystal devices can be omitted, low power consumption for many information equipment and office equipment is realized, thus leading to suppression of global warming and a terrestrial environment protection.
In the circumstances, a low power consumption-type reflection liquid crystal device without using a backlight has been developed but still leaves room for improvement in its characteristics at present. Further, various products using a projection-type liquid crystal device as a projector have been commercially available from electrical equipment manufacturers as a large picture-size display. In the field of such a liquid crystal projector, however, a further improvement in brightness (luminance) and/or contrast is required. In order to provide a high-brightness liquid crystal device without using a polarizer, light scattering-type liquid crystal devices, such as one of a polymer-dispersed type and one of a polymer network-type have been developed and proposed (e.g., “'93 Eurodisplay”, p. 397-). However, these liquid crystal devices are still desired to improve driving characteristics, scattering performance and other characteristics.
SUMMARY OF THE INVENTION
In view of the above-mentioned state of the art, an object of the present invention is to provide a liquid crystal device showing a good viewing angle characteristic, a high contrast and a high resolution at a high productivity.
Another object of the present invention is to provide a liquid crystal device capable of exhibiting high performances, such as a high luminance and a low power consumption.
Another object of the present invention is to provide an optical modulation device, a display device and a liquid crystal apparatus using such a liquid crystal device.
A further object of the present invention is to provide a liquid crystal composition suitably used as a functional material in such a liquid crystal device.
According to the present invention, there is provided a liquid crystal device comprising: a layer of discotic liquid crystal placed in an edge-on and uniaxial alignment state.
According to another aspect of the present invention, there is provided a liquid crystal composition comprising: a discotic liquid crystal and a rod-shaped liquid crystal disposed in mutually separate phases, wherein the discotic liquid crystal is in a nematic discotic phase.
The present invention further provides a liquid crystal device, including a liquid crystal layer comprising a discotic liquid crystal and a rod-shaped liquid crystal disposed in mutually separate phases, wherein the discotic liquid crystal is in a nematic discotic phase.
The present invention further provides a liquid crystal apparatus including a liquid crystal device as described above.
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.
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'93 Eurodisplay, p. 397, Reflective mode PDLC displays—Paper white display P.Nolan, M. Tillin, D. Coates, E. Ginter *, E. Lueder, *, T. Kallfass Merck Ltd, Poole, England *Universitat Stuttgart, Stuttgart, Germany.
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Canon Kabushiki Kaisha
Dudek James
Fitzpatrick ,Cella, Harper & Scinto
Rude Timothy L
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