Patent ID: 7588807

Claim:
A retardation film comprising a stretched polymer film containing a styrene-based resin and a polycarbonate-based resin, which satisfies the following expressions (1) and (2): 100 nm≦Re[590]≦350 nm (1) 0.2 ≦Rth[ 590 ]/Re[ 590]≦0.8 (2) (in the expressions (1) and (2) , Re [590] and Rth[590] respectively represent in-plane retardation and thickness direction retardation values of the film measured by using light of a wavelength of 590 nm at 23° C.); wherein a content of the styrene-based resin is 10 to 40 parts by weight with respect to 100 parts by weight of a total solid content; and wherein an absolute value of photoelastic coefficient of the retardation film measured by using light of a wavelength of 590 nm at 23° C. is 2.0×10 − to 8.0×10 −11 m 2 /N.