| 摘要 |
PROBLEM TO BE SOLVED: To solve problems of changes due to the phase difference by double refraction of a liquid crystal and to the viewing angle as well as of the dependence of these characteristics on wavelengths by using a combination of two or more kinds of phase difference films having different refractive index characteristics. SOLUTION: As for the phase difference plate, a combination of two or more kinds of phase difference films having different refractive index characteristics is used. The phase difference film used shows the refractive index characteristics of nx=ny>nz, nx>ny>nz, nx>ny=nz, nx>nz>ny, nx=nz>ny, nz>nx>ny or nz>nx=ny, wherein nx and ny are the principal refractive indices (nx>=ny) in the plane and nz is the refractive index in the thickness direction. Thereby, the wavelength dependence can be controlled by using the combination of the films having different wavelength dependence. By disposing the slow phase axes of the film in a crossing state, (pseudo) optical rotatory property can be imparted, and the problem of the difference in the double refraction characteristics depending on the aligned state of the liquid crystal can be solved. Thus, not only changes due to the phase difference by double refraction of the liquid crystal or to the viewing angle but the wavelength dependence of these characteristics can be compensated. |
