Transient state liquid crystal image bar with contrast enhanceme

Details Transient state liquid crystal image bar with contrast enhanceme Transient state liquid crystal image bar with contrast enhanceme

Filed on

1986-12-04

Date issued

1988-08-30

Examiner

Miller, Stanley D.

Other Related Categories

350331R, 350334, G02F 113

Type

Patent

Status

active

Patent number

047671904

Description

ABSTRACT:
An improved transient state liquid crystal image bar having enhanced contrast with lower required driving voltage. The image bar is of the type having a nematic liquid crystal cell configured as a single array of dot shutters energizable by a single freqency voltage with crossed polarizer and analyzer. The polarizing axis of the polarizer is at 45 degrees with the liquid crystal molecules in their rest state. Thus, when all the image bar shutters are energized, it is in the non-transmission condition. For bursts of light to pass, the voltage to selected dot shutters are interrupted and reapplied. In one embodiment, the improvement is achieved by an optical compensator or thin prism placed between the polarizer and the liquid crystal cell. In another embodiment, a quarterwave plate is placed between the liquid crystal cell and the analyzer, with the analyzer being rotated about the image bar's optical axis a predetermined angle from its initial crossed position with respect to the polarizer, so that there is increased extinction of the light exiting from the liquid crystal cell, when the liquid crystal material is in its normally stable energized state.

REFERENCES:
patent: 3784280 (1974-01-01), Bigelow
patent: 3863246 (1975-01-01), Trcka
patent: 3900248 (1975-08-01), Nagasaki
patent: 3912369 (1975-10-01), Kashnow
patent: 4019808 (1977-04-01), Scheffer
patent: 4212048 (1980-07-01), Castleberry
patent: 4408839 (1983-10-01), Wiener-Avnear
patent: 4497542 (1985-02-01), Kaye
patent: 4595259 (1986-06-01), Perregaux
patent: 4701028 (1987-10-01), Clerc et al.
"Performance of a Matrix Display Using Surface Mode;" J. L. Fergason; 1980 Biennial Display Research Conference; pp. 177-179, 1980 IEEE.

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