Patent ID: 7541074

Claim:
An optical film comprising a polycarbonate copolymer, the polycarbonate copolymer comprising a repeating unit represented by formula (A) and a repeating unit represented by formula (B), the repeating unit represented by formula (A) amounting to 30 to 80 mol % of the polycarbonate copolymer, the optical film satisfying formulae (1) to (4): 0.1 <Re (450)/ Re (550)<0.95 (1) 1.03 <Re (650)/ Re (550)<1.93 (2) 0.54<( Re (450)/ Rth (450))/( Re (550)/ Rth (550))<0.72 (3) 1.18<( Re (650)/ Rth (650))/( Re (550)/ Rth (550))<1.47 (4) wherein Re(λ) represents an in-plane retardation value by nm of the optical film for a light having a wavelength of λnm, and Rth (λ) represents a retardation value by nm in a thickness direction of the optical film for a light having the wavelength of λnm; wherein R 1 to R 8 each independently represents an at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group containing from 1 to 6 carbon atoms, and X represents formula (X): wherein R 9 and R 10 each independently represents a hydrogen atom, a halogen atom or an alkyl group containing from 1 to 3 carbon atoms; wherein R 11 to R 18 each independently represents an at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group containing from 1 to 22 carbon atoms, and Y represents a group selected from the following groups: wherein R 19 to R 21 , R 23 and R 24 each independently represents at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group containing from 1 to 22 carbon atoms, R 22 and R 25 each independently represents an at least one group selected from the group consisting of hydrocarbon groups containing from 1 to 20 carbon atoms, and Ar 1 to Ar 3 each independently represents at least one group selected from the group consisting of aryl groups containing from 6 to 10 carbon atoms.