Liquid Crystal color display devices for positive type are investigated. Guest Host Mode characterized by specific molecular alignment is proposed. Display devices are designed so that without applied voltage, the molecular aligment of Nn LCs is quasi homeotropic through alignment layers, and shows a twisted-like structure between substrates. While with a voltage applied, the molecular alignment is transited from quasi homeotropic twisted stage to planer twisted stage, keeping the twisted-like structure. Therefore, the pleochroic dye added in Nn Lcs absorbs the incident light when the voltage applied, thus providing a positive type display from the colorless state to the colored state. In this paper, optical properties, particularly, effects of optical anisotropy and thickness are discussed compared with conventional Nn type Guest Host Mode.
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