<title>Gray-scale and contrast compensator for LCDs using obliquely oriented anisotropic network</title>

Abstract

Birefringent optical compensators containing layers with substantially inclined optic axes can improve not only the contrast but also the gray scale and chromatic stability of 900twisted nematic LCDs over a large field of view. We present the detailed architecture of such a compensator. It consists of multiple birefringent layers, including one with an in-plane optic axis, one with its optic axis normal to the plane, and two with optic axes inclined at about 400 from the plane. The in-plane and inclined layers are fabricated by photopolymerization of oriented liquid crystal monomers to form anisotropic networks. The precise thicknesses and azimuthal orientations of the various layers are determined by computer optimization. Laboratory measurements of compensated display units show good contrast, gray level, and chromatic stability over a large field of view. The performance is suitable for demanding avionics applications. These compensators are currently being fabricated at the Rockwell Science Center.