Patent ID: 7267849

Claim:
A compensator for a liquid crystal display comprising at least one layer of a birefringent material wherein the birefringent material has a crystal structure formed by at least one polycyclic organic compound with conjugated π-system, and an intermolecular spacing of 3.4±0.3 Å is in the direction of at least one of optical axes, wherein the organic compound is an acenaphtho[1.2-b]quinoxaline sulfoderivative of the general structural formula: where n is an integer in the range of 1 to 4; m is an integer in the range of 0 to 4; z is an integer in the range of 0 to 6, and m+z+n≦10; X and Y are individually selected from the group consisting of CH 3 , C 2 H 5 , OCH 3 , OC 2 H 5 , Cl, Br, OH, and NH 2 ; M is a counterion; and j is the number of counterions in the molecule.