| 摘要 |
PURPOSE:To elevate a display contrast, by reversing the twisted direction of a 2-layer twisted pneumatic liquid crystal cell, between 2 layers, so that the visual angle ranges for giving a contrast after converting the orientation are made to conform to each other, and adequately selecting the product of double refraction DELTAn and layer thickness (d). CONSTITUTION:As for an upper liquid crysral layer 2a and a lower liquid crystal layer 2b, the layer thickness da, db is about 6mum, their twisted directions are reverse to each other, and in the figure, the liquid crystal layer 2a shows twist in the right direction, and the liquid crystal layer 2b shows twist in the left direction. When the orientation processing as shown in the figure is executed, and a tilt angle is selected within the range of about 2-5 deg., both the directions being satisfactory in a contrast of each liquid crystal cell coincide with each other, and the angle of rotation becomes 0 deg. extending over a visible light wavelength range, by 2 layers of liquid crystal, therefore, an interference color in the background is little, and a display contrast becomes satisfactory. As for the product of layer thickness of the liquid crystal layer, and double refraction, it is desirable that it is within the range between 0.36mum and 0.65mum in the respective layers, and the ratio of the respective values is >=0.8 and <=1.2. |
