Liquid crystal cell with opaque mask for printing device
US4810062A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 16, 1987 |
| Grant date | Mar 7, 1989 |
| Priority date | — |
| Expiry date | Dec 16, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/13439
- WIPO fieldOptics
- WIPO sectorInstruments
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 a optically inactive nematic liquid crystal and an optically active liquid crystal m…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.