Rockwell Collins, Inc.

University of Rochester

Sushil Krishnamurthy

Michael H Kalmanash

Shaw H Chen

Hongqin Shi

Gayathri Sundaresan

John C Mastrangelo

The projection screen assembly minimizes speckle while preserving high ambient viewability. The screen assembly, having a light-source side and a viewing side, includes a screen layer, a polarizing contrast filter, and a speckle contrast reducing layer. The screen layer disperses light passing through the screen assembly from the light-source side. The polarizing contrast filter is disposed on the viewing side of the screen layer and reduces ambient glare. The speckle contrast reducing layer is disposed on the light-source side of the screen layer and reduces speckle formed in projected images on the viewing side of the screen assembly.

Projection screen with reduced speckle

A secondary image suppression system (SISS) for minimizing secondary ghost images in a screen assembly for a rear projection system. The secondary image suppression system includes a circular polarizing assembly positioned to receive light from a rear projection lens of a rear projection system. The circular polarizing assembly includes a linear polarizer and a quarter wave retarder. The linear polarizer and the quarter wave retarder are serially positioned relative to each other and are assembled with a high power Fresnel lens using index matching media such that internal reflections are minimized. The high power Fresnel lens is positioned to receive output from the circular polarizing assembly. During use, light from a projection lens of a rear projection system is introduced through the circular polarizing assembly and through the high power Fresnel lens toward a viewing screen. Any significant secondary ghost images are eliminated by the circular polarizing assembly. The SISS may be combined with a high contrast screen assembly to improve high ambient contrast while avoiding the necessity for beaded films or other structured screens that could cause viewing artifacts.

System for eliminating secondary images in rear projection systems

A thermotropic chiral nematic liquid crystalline copolymer composition comprises ##STR1## wherein --NEM-- and --NEM'-- are each independently nematogenic units of formula ##STR2## wherein R is H or CH.sub.3, --Q-- is an alkylene radical having 1 to about 8 carbon atoms,

Growing community of inventors

Sunnyvale, CA, United States of America

Sushil Krishnamurthy