Patent ID: 8139188

Claim:
A biaxial retardation film, wherein the biaxial retardation film satisfies the following equations: 220 nm≦ Rxy (550)≦330 nm 110 nm≦ Rxz (550)≦165 nm 0.75 ≦Rxy (450)/ Rxy (550)≦0.97 1.03 ≦Rxy (650)/ Rxy (550)≦1.25 where in said equations Rxy(λ), Rxz(λ) represent the retardation Rxy, Rxz of the biaxial retardation film at wavelength λnm respectively, and are defined as Rxy=(nx−ny)×d, Rxz=(nx−nz)×d, where nx, ny(nx>ny) are principal refractive indices in an in-plane direction, nz is a principal refraction index in an out of plane direction, and “d” is a thickness in the biaxial retardation film.