Patent ID: 7428029

Claim:
An optical film comprising a transparent polymer film layer and a birefringent layer formed of a non-liquid crystalline polymer that are laminated together, wherein the birefringent layer satisfies conditions represented by the following formulas (1) and (2), and the transparent polymer film layer has an in-plane retardation of not more than 50 nm: nx≧ny>nz (1) Δ n ( a )>Δ n ( b )×10 (2) in the formula (1), nx, ny and nz indicate respectively refractive indices in an X-axis direction, a Y-axis direction and a Z-axis direction in the birefringent layer; the X-axis direction is a direction showing a maximum refractive index within the plane of the birefringent layer, the Y-axis direction is a direction perpendicular to the X-axis direction within the plane, and the Z-axis direction is a thickness direction and is perpendicular to the X-axis direction and the Y-axis direction, and in the formula (2), Δn(a) indicates a birefringence of the birefringent layer and Δn(b) indicates a birefringence of the transparent polymer film layer.