PB29 Optimization of Chiral Pitch of LC Material for the Bistable Twisted Nematic LCD by Using N^*LC of Δε<0

Abstract

Novel type of bistable LCD by using the N^* LC material with Δε<0 is investigated. There is a possibility that an optical high contrast ratio is obtained, because the pure black image is simply able to obtain by using the vertical alignment state. Such as display holding time and the d/P₀ ratio to induce the bistable states are important parameters for the bistable LCD. In this paper, the observation and the evaluation of the display in the wedge shaped cell were carried out to achieve the improvement of display holding time when the cell thickness d and d/P₀ ratio were varied. As a result, the region of d/P_0 for obtaining the bistable state was extended within d/P₀=0.52〜0.84 (Δ[d/P₀]=0.32) in the cell with P₀=12.48μm, however, d/P₀=0.68〜0.94 (Δ[d/P_0]=0.26) in the cell with P₀=7.21μm.