| US 7,541,074 B2 | ||
| Optical film and optical compensatory film, polarizing plate and liquid crystal display using same | ||
| Hajime Nakayama, Minami-Ashigara (Japan); and Yusuke Ohashi, Minami-Ashigara (Japan) | ||
| Assigned to Fujifilm Corporation, Minato-Ku, Tokyo (Japan) | ||
| Filed on Aug. 16, 2006, as Appl. No. 11/504,631. | ||
| Claims priority of application No. 2005-236856 (JP), filed on Aug. 17, 2005. | ||
| Prior Publication US 2007/0190268 A1, Aug. 16, 2007 | ||
| Int. Cl. G02F 1/13363 (2006.01) | ||
| U.S. Cl. 428—1.3 [428/412; 349/117; 349/118] | 15 Claims |

| 1. 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;
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