Patent ID: 7105213

Claim:
An optical compensation film comprising a cellulose ester film comprising cellulose ester wherein (a) each of photoelastic coefficient C(md) in a mechanical direction and photoelastic coefficient C(td) in a transverse direction of the cellulose ester film is 1×10 −9 to 1×10 −13 Pa −1 , and C(md)<C(td), (b) retardation R 0 within a plane of the cellulose film defined by Formula (I) is 20 to 70 nm, (c) retardation R t of the cellulose ester film in a thickness direction defined by Formula (II) is 70 to 400 nm, (d) each of a dimensional variation ratio S(md) in the mechanical direction and a dimensional variation ratio S(td) in the transverse direction of the cellulose ester film prior to and after being allowed to stand at ambient conditions of 80° C. and 90 percent relative humidity for 50 hours are −1 to 1 percent, |S(md)|>|S(td)|, and (e) C(td)×|S(td)|<C(md)×|S(md)|, wherein R 0 =( nx−ny )× d (I) R t ={( nx+ny )/2− nz}×d (II) wherein nx is a refractive index in a transverse direction within a plane, ny is a refractive index in a mechanical direction within a plane, nz is a refractive index in a thickness direction of the film, and d is a thickness of the film in nm.