Electrooptic properties of nematic liquid crystal displays

Liquid Crystal Displays are suitable candidates for the application in flat panels as well as in projection systems. There is a large variety of electrooptic effects mainly based on thin nematic layers with a twist ranging from 0 to 270 degree. In order to optimize a display it is necessary to adapt the electrooptic effect to the requirements addressing scheme used for the specific application. The electrooptic properties are strongly dependent on material and cell parameters such as elastic and dielectric constants, the viscosities, the ratio of pitch over cell thickness, the overall twist and the pretilt at the substrate. In addition the refractive index anisotropy must be adjusted to the specific liquid crystal configuration. Based on Berremans work some general guide lines for the optimization of twisted structures will be discussed. In addition results will be presented of a detailed analysis of twisted structures adapted to the application in flat panels and to transmissive as we ll as reflective type projection systems.