探討扭曲配向液晶盒及垂直配向液晶盒內雜質離子之特性

Abstract

本論文分析了垂直配向液晶盒及扭曲配向液晶盒內部的離子效應，實驗量測上使用外差干涉儀、電感電容電阻量測儀、半導體參數分析儀，理論分析上使用T. C. Chieu和K. H. Yang提出之離子運動方程式，將實驗與理論進行結合後即可得出離子的物理參數。 利用外差干涉儀來量測高頻(1 kHz)下相位差與電壓之關係(Ph-V)，接著在低頻(0.1 Hz)下施加一方波電壓量測相位差隨時間之變化(Ph-T) ，將上述得到之實驗結果進行分析後，即可得知液晶盒內之離子效應是由配向層中的離子所主導或是液晶層中的離子所主導。 將實驗結果及理論進行擬合分析後，即可推導出液晶盒中配向層及液晶層中之高、低解離率離子之方程式，進行計算後可得到液晶盒中高、低解離率離子之離子濃度、遷移率及活化能，並從擬合的R-square可展示實驗數據與理論推導的吻合程度。

We have studied ionic phenomena of rubbed-polyimide(PI)-aligned liquid crystal(LC) cells, a vertical alignment (VA) and a twisted nematic(TN). We have used a heterodyne interferometer, a LCR meter, an ammeter and semiconductor-parameter analyzers to measure all the ion-related data and analyzed data by using ion generation and transport equations published by Chieu and Yang. The heterodyne interferometer was used to measure phase versus RMS voltage (at 1 kHz) (Ph-V), and phase versus time(Ph-t) by applying a middle-gray-scale voltage to the cell at 0.1 Hz. From data of Ph-V and Ph-t curves, we can differentiate if the electro-optical behaviors of the cell were dominated by either ions in PI alignment layers or ions in the LC medium within the cell. We have used a VA cell for the investigation of the former, and a TN cell for the investigations of the former at room temperature and for the latter at 60o C. By fitting experimental results to theoretical analyses, we have derived the physical parameters of high-ionization–rate (HIR) and low-ionization–rate (LIR) ions in the alignment layers and the LC medium with the LC cell. We have obtained physical parameters of ion concentrations, ion mobility, the associated activation energies of HIR ions and LIR ions, and other parameters for both the PI- and LC-ion-dominated cases. We have calculated R-square values to indicate the discrepancy between our experimental results and theoretical analyses.