Patent ID: 7456918
Filing Date: 2008-11-25
Classification: G02F

Abstract:
1. A compensator for use in a liquid crystal display (LCD) of the bend mode, comprising at least one retardation film having a film plane and an extraordinary axis substantially parallel to the film plane thereof (A plate), at least one retardation film having a film plane and an extraordinary axis tilted at an angle θ between 0° and 90° relative to the film plane thereof (O plate), and at least one retardation film having a film plane and an optical axis substantially perpendicular to the film plane thereof and having a refractive index in the direction perpendicular to the film plane thereof that is smaller than the refractive indices in the directions parallel to the film plane thereof (negative C plate), wherein the optical retardation of the individual A, O and C plates of the compensator are selected such that the following equations are fulfilled wherein d is the layer or film thickness, Δn is the birefringence, d A ·Δn A is the retardation of the A plate, d O ·Δn O is the retardation of the O plate, d C ·Δn C is the retardation of the of the negative C plate, and d LC ·Δn LC is the retardation of the switchable LC cell of the display.