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Twisted Nematic Liquid Crystal Replacement for Overhead Transparency Disclosure Number: IPCOM000039043D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01

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Wallace, SE Whittle, DJ [+details]


This article describes techniques for improving the contrast of a projection display system consisting of a twisted nematic liquid crystal display (TNLCD) used as an electronic transparency, or liquid crystal foil (LCF), on a conventional overhead projector. The LCF shares the desirable characteristics of disposable thermal film transparencies such as previewing before and during projection, as well as direct annotation. Advantages of this system over alternate projection systems for this business meeting application include portability, the inversion of contrast polarity through rotation of one of the polarizers, simple extension to color, and low system cost through the use of mature liquid crystal technology, and the widespread availability of overhead projectors.