Bi and multi stable ferroelectric liquid crystal displays

Ferroelectric liquid crystal (FLC) attracted more and more interesting for display application long time ago. Because of good bistability and very fast switching time, FLC display has potential in field sequential color (FSC) and bistable display applications. However, there are two problems to stop FLC technology popular in display market for these years. First is how to receive good alignment on large size substrate. Second is how to achieve analog gray scales. The purpose of this thesis is trying to solve these two problems for FLC technology in bistable display application. In order to avoid “surface destroy” and static charge accumulation problems, two non-contacting methods are proposed, which are photo-alignment technology and SiO2 thin films by ion beam deposition method. At the same time, SiOx surface using oblique evaporation method is investigated, in order to compare with characteristics of SiO2 thin films. After discussion for these non contacting techniques, we will investigate the multi stable effects in FLC cells for analog gray scale generation in FLCDs. Domain structures are much more stable for LPI’s materials, compared with Felix mixtures in the experiments. Theory description will be given to explain the reason. Uniform model is set up to describe the switching process of FLC molecule director under electrical pulse. From this model, intrinsic analog gray scale is forecasted and simulated. Driving principles will be discussed for gray scale generation and stabilization. Based on the results, we successfully demonstrated a passive 160x160 multiplex addressing photo-aligned 5μm reflective FLCD with high contrast and four memorized gray scale levels