Pages 47-52
We investigated influences of the protective layers of polarizers on the viewing angle characteristics of STN-LCDs using a numerical simulation based on Berreman's 4x4 matrix formulation. Usually triacetylcellulose (TAC) is used for the protective layers since its in-plane retardation is small enough not to affect optical properties in normal direction. However, its out-of-plane retardation is relatively large so that it affects the viewing angle characteristics. We found that the conventional protective layers worsen the viewing angle characterisitics of STN-LCDs, and that the viewing angle characereistics can be improved remarkably by increasing the twist angle and optimizing the out-of-retandation of both the protective layers and compensation films.
