| 摘要 |
PURPOSE:To provide a good contrast, brightness and wide visual field angle by respectively specifying the product of the refractive index anisotropy and thickness of liquid crystals and the refractive indices of three directions of double refractive plates. CONSTITUTION:This color liquid crystal element has a liquid crystal layer which has a twist angle of 150 to 300 deg. by nematic liquid crystals which contain optically rotatory materials clamped between a pair of substrates with transparent electrodes arranged in nearly parallel and having orientation control films, and have positive dielectric anisotropy and a driving means for impressing voltage between the transparent electrodes of the upper and lower substrates clamping this liquid crystal layer. A pair of polarizing plates 1, 2 are installed on the outer sides of the liquid crystal layer and a pair of the double refractive plates 4A, 4B are arranged on both outer sides of the liquid crystal layer and on the inner sides of a pair of these polarizing plates 1, 2. The inside surfaces of the cells are provided with color filters. The product DELTAn1.d1 of the refractive index anisotropy DELTAn1 of the liquid crystals in the liquid crystal layer and the thickness d1 of the liquid crystal layer is specified to 0.4 to 1.5mum. The double refractive plates 4A, 4B vary in the refractive indices in the three directions and are so formed as to attain nx>nz>ny when the main refractive indices of three pieces are defined as nx, ny, nz, and nx, ny are defined as the refractive indices in the intra-surface direction of the double refractive plates (nx>ny) and nz is defined as the refractive index in the thickness direction. |
