| US 7,538,841 B2 | ||
| Optical film, liquid crystal panel, and liquid crystal display apparatus | ||
| Nao Murakami, Ibaraki (Japan); Kentarou Takeda, Ibaraki (Japan); Yoshiyuki Kiya, Ibaraki (Japan); and Hiroyuki Yoshimi, Ibaraki (Japan) | ||
| Assigned to Nitto Denko Corporation, Ibaraki-shi, Osaka (Japan) | ||
| Filed on May 10, 2006, as Appl. No. 11/430,907. | ||
| Claims priority of application No. 2005-152311 (JP), filed on May 25, 2005; and application No. 2006-044888 (JP), filed on Feb. 22, 2006. | ||
| Prior Publication US 2006/0268208 A1, Nov. 30, 2006 | ||
| Int. Cl. G02F 1/1335 (2006.01); G02F 1/1347 (2006.01) | ||
| U.S. Cl. 349—117 [349/118; 349/75] | 18 Claims |
| 1. An optical film comprising a first transparent protective film, a polarizer, a second transparent protective film, and
a birefringent layer having a relationship of nx>ny=nz and positive uniaxial property in the stated order, wherein
the second transparent protective film has a thickness direction retardation (Rth) represented by the formula (1) of 10 nm
or less
Rth=(nx−nz)×d (1);
d (nm) represents a thickness of the second transparent protective film;
nx refers to a refractive index in a direction providing a maximum in-pane refractive index (a slow axis direction);
ny refers to a refractive index in a direction perpendicular to the slow axis in the same plane (a fast axis direction);
nz refers to a refractive index in a thickness direction.
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