Photocopying – Contact printing – Light boxes
Patent
1985-06-10
1990-05-22
Miller, Stanley D.
Photocopying
Contact printing
Light boxes
350350R, 350331R, 350 9624, 355 71, G02F 113
Patent
active
049272420
ABSTRACT:
A high-speed responsive liquid crystal optical device with improved light transmissivity is provided. The device includes a liquid crystal panel including an optically active liquid crystal material having dielectric anisotropy which becomes zero at a crossing frequency ("fc") of 100 KHz or below. The dielectric anisotropy of the liquid crystal is positive at frequencies lower than fc ("fl") and negative at frequencies higher than fc ("fh"). Crossed polarizers are disposed on each side of the liquid crystal panel. A liquid crystal driving circuit selectively applies a signal of a frequency fh to open the device and a signal of a frequency fl to close the device. The optical device is particularly well suited for use as a light valve in a printer device. Response time within 1 m sec. permits a printing speed of 10 prints of A4 size to be produced per minute with a resolving power of about 10 dots per 1 m/m. This amounts to a printing speed of approximately 500 lines in one second with each line being written into m sec. or less. The optically active nematic liquid crystal is a composition comprising an optically inactive nematic liquid crystal and an optically active liquid crystal material added thereto.
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Aoki Kenji
Miura Teiji
Nagata Mitsuo
Nakamura Haruo
Kaplan Blum
Miller Stanley D.
Seiko Epson Corporation
Thantu Napoleon
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