폴리이미드 표면에서의 네마틱 액정의 틸트 제어를 이용한 High Tilted OCB(HTOCB) 모드

Abstract

In this paper, we have improved a novel high tilted optically compensated bend (OCB) (HTOCB) mode by using high tilt angle that was generated by the unique baking condition on the homeotropic alignment layer. The high tilt angle of liquid crystal (LC) was generated by new alignment process that tilt angle changed homeotropic state to homeogenous state using Hot-plate equipment; we obtained about <TEX>$40\~50^{\circ}$</TEX> tilt angle with negative and positive dielectric anisotropy on the homeotropic polyimide (PI), and then LC tilt angle decreased as increasing baking temperature and time. At last, we obtained about <TEX>$10^{\circ}$</TEX> with positive type NLC <TEX>$({\Delta}n>0)$</TEX>. Also, the LC tilt angle of positive type NLC <TEX>$({\Delta}n>0)$</TEX> decreased as increasing rubbing strength at the same baking temperature and time. The novel LC operating mode (HTOCB) that used the high tilt angle by the new alignment method was improved. The response time of the novel HTOCB cell was faster than that of conventional OCB cell. We suggest that the developed the novel HTOCB cell using control of tilt angle on the homeotropic surface is a promising technique for the achievement of a fast response time and a high contrast ratio.