Patent ID: 8284358

Claim:
A retardation film comprising: an optical axis out of plane and where extraordinary ray refraction index>ordinary ray refraction index, wherein the retardation film satisfies the following equations (e) to (h): 0 nm≦ Rxy (550)≦10 nm (e) −107 nm≦ Rxz (550)≦−71 nm (f) 0.75 ≦Rxz (450)/ Rxz (550)≦0.97 (g) 1.03 ≦Rxz (650)/ Rxz (550)≦1.25 (h), in equations (e) to (h), Rxy(λ), Rxz(λ) represent the retardation Rxy, Rxz of the retardation film at wavelength λnm respectively, and are defined as Rxy=(nx−ny)×d, Rxz=(nx−nz)×d, where nx, ny (nx>ny) are the principal refraction indexes in the in-plane direction, nz is the principal refraction index in the out of plane direction, and “d” is a thickness in the retardation film.