Patent ID: 7625612

Claim:
A retardation film comprising a stretched film of a polymer film having an absolute value of photoelastic coefficient (m 2 /N) of 50×10 −12 or less measured by using light of a wavelength of 550 nm at 23° C., which satisfies the following expressions (1) and (2): Re[450]<Re[550]<Re[650] (1) Rth[550]<Re[550] (2) in the expressions (1) and (2): Re[450], Re[550], and Re[650] respectively represent in-plane retardation values measured by using light of wavelengths of 450 nm, 550 nm, and 650 nm at 23° C.; and Rth[550] represents a thickness direction retardation value measured by using light of a wavelength of 550 nm at 23° C.; and which has an Nz coefficient of 0.2 to 0.8; wherein the Nz coefficient is a ratio of Rth[550]/Re[550] between the thickness direction retardation value and the in-plane retardation value measured by using light of a wavelength of 550 nm at 23° C.