| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase difference plate which generates λ/4 phase differ ence in a wide wavelength range by one sheet of a polymer film and which increases the viewing angle of a liquid crystal display device, and which shows no changes in the optical characteristics. SOLUTION: The phase difference plate consists of one sheet of a polymer film which has retardation (Re450) measured at 450 nm wavelength ranging from 100 to 125 nm and retardation (Re590) measured at 590 nm wavelength ranging from 120 to 160 nm and satisfies the relation of Re590-Re450>=2 nm. The refractive index nx in the direction of the slow phase axis in the film plane, the refractive index ny in the direction perpendicular to the slow phase axis in the plane, and the refractive index nz in the thickness direction satisfy the relation of 1<=(nx-nz)/(nx-ny)<=2. The thickness of the polymer film ranges from 10 to 70 μm. |
