Browse Prior Art Database

GUEST-HOST LIGHT VALVE

IP.com Disclosure Number: IPCOM000025516D
Original Publication Date: 1985-Dec-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 74K

Publishing Venue

Xerox Disclosure Journal

Abstract

An optically addressed liquid crystal light valve based on the guest-host effect is disclosed in the figure. Generally, in the absence of imaging light the electric field drops essentially across the photoconductor; however, when the photoconductor is imagewise exposed, the field drops imagewise across the liquid crystal film inducing optical changes which can be read-out with the aid of polarizers (twisted nematic effect). Between the photoconductor and the liquid crystal is in some cases an optical blocking layer to prevent the read-out light from interfering with the imaging light. In other cases, depending on the photoconductor, or the wavelength of read-out light used, a blocking layer is not required. See U.S. Patent No. 4,037,932.

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XEROX DISCLOSURE JOURNAL

GUEST-HOST LIGHT VALVE Proposed Werner E. Haas Classification

U.S. Cl. 250/213R Int. C1. HOlj 31/50

POLARIZER 0'

+ +POLARIZER 900

INDIUM \I

OXIDE \ I GLASS \ I I SILICON MONOXIDE
PHENOXY

    A GLASS INDIUM/ I

r

I

Volume 10 Number 6 November/December 1985 323

1 OXIDE

IMAGING LIGHT

[This page contains 1 picture or other non-text object]

Page 2 of 2

GUEST-HOST LIGHT VALVE (Cont'd)

An optically addressed liquid crystal light valve based on the guest-host effect is disclosed in the figure. Generally, in the absence of imaging light the electric field drops essentially across the photoconductor; however, when the photoconductor is imagewise exposed, the field drops imagewise across the liquid crystal film inducing optical changes which can be read-out with the aid of polarizers (twisted nematic effect). Between the photoconductor and the liquid crystal is in some cases an optical blocking layer to prevent the read-out light from interfering with the imaging light. In other cases, depending on the photoconductor, or the wavelength of read-out light used, a blocking layer is not required. See U.S. Patent No. 4,037,932.

Since the figure is a light valve based on the liquid crystal guest-host effect this effect will not be discussed in detail. Generally, in the guest-host effect, pleochroic dye molecules (guest) are dispersed in the liquid crystal (host). Under the influence of electric fields the liquid crystal molecules could become aligned and in tu...