Patent ID: 6853423
Filing Date: 2005-02-08
Classification: G02B,G02F

Abstract:
1. A quarter wave plate comprising an optically anisotropic layer A and an optically anisotropic layer B, said optically anisotropic layer A having a retardation value in the range of 210 to 300 nm when the retardation value is measured at the wavelength of 550 nm, and said optically anisotropic layer B having a retardation valve in the range of 115 to 150 nm when the retardation value is measured at the wavelength of 550 nm, said quarter wave plate having a ratio of a retardation value to a wavelength in the range of 0.2 to 0.3 when the retardation value is measured at the wavelength of 450 nm, 550 nm and 650 nm, wherein one of the optically anisotropic layers A and B is a layer made from liquid crystal molecules, and the other is a polymer film.