表面特性對表面穩定型鐵電性液晶影響之研究

Abstract

近年來液晶顯示器挾其輕薄之優勢已成功取代傳統桌上型映像管顯示器，並積極上下延伸至各種尺寸之顯示器應用。然而在大尺寸應用上，動態表現因受限於扭轉型液晶較慢的反應速度，而無法提升影像品質。因此具有快速應答速度的鐵電性液晶已然成為下一波備受矚目的液晶材料。表面穩定型鐵電性液晶顯示器是目前廣為使用的技術，除了反應時間快，視角範圍也較傳統液晶顯示器大，然而結構上不易排列及衍生出的缺陷卻是目前亟欲解決的問題。 表面穩定的機制是在極狹小的液晶盒間隙中，利用表面的配向力將SmC*液晶相的螺旋結構破壞並固定液晶分子的方向，因此表面的特性對於鐵電性液晶的排列來說是非常重要亦值得深究。本篇論文特別針對配向膜的正負極性以及和自發性極化的耦合作用做探討，並依此建構出一可控制自發性極化方向之液晶盒結構。利用此種液晶盒結構，可形成單一方向排列之層結構，並解決水平山形袖章結構之缺陷進而提升對比。除此之外，本篇論文亦針對表面平坦度的改善及摩擦配向對鐵電性液晶排列之影響提出討論。

Fast switching LCD technology is essential for achieving high dynamic image quality. For this reason, ferroelectric liquid crystal (FLC) which has fast response speed is highly concerned. Surface stabilized ferroelectric liquid crystal (SSFLC) is a widely used technique and promising solution for the next generation of LC displays, but the occurrence of alignment defects bring down the practicability. In this thesis, the influences of surface properties such as sign of surface polarity, surface roughness and surface rubbing conditions on alignment in SSFLC device were studied. In addition, by utilization of sign of surface polarity, a uni-direction layer model was proposed to control the direction of spontaneous polarization. Based on this model, the hybrid cell structure succeeded in eliminating the horizontal chevron defect without application of electric field and higher contrast ratio, over 100, was also achieved.