LIGHT-SCATTERING AND CONTRAST IN THERMALLY ADDRESSED LIQUID-CRYSTAL DISPLAYS

The effects of structural order on the light scattering characteristics of liquid crystal display cells containing smetic p-n-octyl-p prime -cyanobiphenyl were investigated. The scattering characteristics of different structures in the cell due to surface treatments are qualitatively analyzed for their effects on the contrast ratio when used in the thermally addressed liquid crystal display (TALC). Of the four structures investigated, i. e. , homeotropic, fan-like, uniaxial rods and spherulites, the spherulitic structure was found to exhibit the scattering profile best suited for high contrast because of the near-zero scattering near the incident beam. Based on the light scattering theory for spherulites, optimization of structural parameters such as size and order of spherulites, and device design such as collecting angle of projection lens for maximum display contrast was predicted. Methods to improve contrast are also discussed.