Patent ID: 7456919
Filing Date: 2008-11-25
Classification: G02F

Abstract:
1. An optical film comprising: a polarizer having an absorption axis; and at least three retardation films, each having a slow axis, wherein the absorption axis of the polaration intersects the slow axis of each of the least three retardation films at right angles and is parallel to the slow axis of each of the at least three retardation films, the slow axis of each of the at least three retardation films are parallel to each other, a total amount of Nz value of each of the at least three retardation films, the Nz value being defined by formula (I), is half as many as the number of the at least three retardation films, and an in-plane retardation Re wherein, on condition that a direction in which the in-plane refractive index of each of the at least three retardation films is maximized is taken as an X axis; a direction perpendicular to the X axis is taken as an a Y axis; and a thickness-direction of the retardation films is taken as a Z axis, nx 1 , ny 1 , nz 1 are refractive index achieved along the X axis, the Y axis and the Z axis, respectively, and d 1 is a thickness of each of the at least three retardation films.