摩擦配向膜的扭轉向列型液晶盒中之離子特性

Abstract

本論文藉由電壓保持率量測以及相位差量測來分析扭曲向列型液晶盒中的離子特性，使用離子產生與傳輸模型搭配理論分析求得液晶混合物與配向膜中各自的高、低解離率雜質離子濃度、離子遷移率等相關物理參數及其溫度效應。本論文的傳輸模型可準確地求出離子濃度、離子遷移率等相關物理參數，並且解決了傳統模型無法解釋的各種離子對扭曲向列型液晶盒光電效應的影響。 目前並不清楚存在於液晶混合物與配向膜中的高、低解離率雜質的來源，我們相信使用本論文所揭示的實驗與分析方法，搭配不同的材料以及製程參數的改變，作進一步的研究，就有可能確認這些高、低解離率雜質離子的來源及其化學結構，更深入的研究可以達成無影像殘留的高品質的液晶顯示器。本論文的量測方法與理論分析也可以應用到採用非接觸式配向膜的液晶盒，探討其所含離子的物理參數和所導致的光電效應。

We have studied ionic effects within rubbed-ITO- and rubbed-polyimide(PI)- aligned twisted nematic (TN) liquid crystal (LC) cells by using heterodyne-phase and voltage-holding-ratio (VHR) measurements on these TN cells as a function of temperature. We have developed numerical analyses based on ion generation and transport equations to fit our measured VHR data to derive temperature-dependent ion concentration and mobility for both high-ionization-rate (HIR) and low-ionization-rate (LIR) impurities within the TN LC mixture and PI alignment layers, respectively. The results of our investigation have shown that both HIR and LIR ions existed in the rubbed-ITO- and rubbed-PI-aligned TN cells containing the same nematic LC mixture. The derived HIR and LIR ionic properties from rubbed-PI-aligned TN cell were different from those obtained from the rubbed- ITO-aligned TN cell implying that there existed ions within the PI alignment layers. In this thesis, we have obtained HIR and LIR ionic properties within the rubbed PI alignment layers of the TN cell. By applying the experimental methods and theoretical model proposed in this thesis to do further studies on samples made of different process steps and various chemical compositions, we hope to reveal the origins and chemical structures of observed HIR and LIR impurities within the LC mixture and PI alignment layers, respectively. Our methods can also be applied to study the ionic properties of LC cells made of non-contact alignment layers. The reduction or elimination of ions in LCDs can accomplish high-quality LCDs without image sticking.