臺灣博碩士論文加值系統

離子效應一直是影響液晶顯示器顯示品質主要因數，在過去由於TN(Twist Nematic)LCD最先被發展出來，因此文獻中大多是研究TN LCD，隨著VA(Vertical Alignment) LC材料的增加，且VALCD對比度佳，被應用在LCD上的也越來越多，在過去VA鮮少被完整討論，所以我們將探討垂直排列負型液晶材料(Δε<0)在低頻之下的離子效應。
本論文將對不同配向膜厚度、材料及不同液晶材料、不同液晶盒厚度所產生的離子效應來作研究及測量，包括：1. 光學量測，2. 電流量測，3. 電容量測。由光學量測可以確定DMR(Depressed molecular reorientation)是由液晶層中離子電荷形成EDL所引起的光學現象；而EMR（Enhanced molecular reorientation）是由配向膜中離子電荷形成EDL（Electric double layer）所引起的光學現象；由I-t電流量測得到離子電荷漂移到界面時的傳輸時間（transit time）以及求得DMR cell及EMR cell的平均遷移率；由電容量測來分析影像殘留部分，DMR cell的影像殘留比EMR cell嚴重且配向膜越厚影像殘留也越嚴重。
另外我們藉由數值分析模擬，找出液晶樣品近似的離子電荷密度（charge density）、界面捕捉率（trap factor）及與配向膜厚度之間的關係。利用不同離子電荷濃下等效電壓增加量對界面捕捉率模擬曲線，找出最小等效電壓增加量時離子電荷密度與界面捕捉率值。

Ionic effects always affect the property of LCD. Since TNLCD was invented earlier than the other LCD products, it has been studied extensively in literature. Recently, VALC (Vertical Alignment Liquid Crystal) materials were proposed for its excellent advantages in high contrasts. More and more applications have adopted VALC materials; however, fewer studies were endeavored in VALC materials. Therefore we focused in the negative (Δε<0) VALC and its ionic effect in low frequency.
This thesis discusses the ionic effects in AL (Alignment Layer) and cell gap of different thickness, including different kinds of AL and LC materials. There are three parts of measurement in the thesis：1. Optical measurement, 2. I-t measurement, 3. C-t measurement. Two optical properties, DMR and EMR, were investigated in the optical measurement. The DMR effect is produced by the EDL which is formed by the ions in the LC layer. The EMR effect is produced by the EDL which is formed by ions in the AL layers. In the I-t measurement, the ions transit time and the average mobility were calculated for the DMR cells and the EMR cells. In the C-t measurement, the DMR cell was more significant than the EMR cell, no matter for the charged time or the discharged time. Hence the image-sticking effect for the DMR cells was shown to be more significant than the EMR cells.
In addition, the relation between the ionic charge density, trap factor and AL thickness can be obtained from the numerical analysis. The effective incensement voltage versus the trap factor for different charge densities was also obtained. The charge density and the trap factor can be obtained when the minimum value of the increased effect voltage was found.

摘 要i
Abstractii
誌 謝iv
目 錄v
圖目錄viii
表目錄xi
縮寫及符號對照表xii
第一章 緒論1
1. 1前言 1
1. 2文獻探討3
1.2. 1電雙極層模型（Electric Double Layers Mode-EDL Mode）3
1.2. 2基本原理說明 5
1.2. 3離子電荷在液晶層中運動行為6
1.2. 4離子電荷在配向膜中運動行為7
1. 3電流部分8
1. 4電容部分9
1. 5數值分析模式（Numerical Analysis Mode）11
1. 6論文研究重點及目的12
第二章 實驗方法13
2. 1樣品製作流程13
2.1. 1製作流程13
2.1. 2不同厚度及材料的配向膜與液晶15
2. 2實驗裝置18
2.2. 1光學架設18
2.2. 2電流量測架設24
2.2. 3電容量測架設25
2. 3實驗量測結果及討論27
2.3. 1 EMR、DMR量測結果27
2.3. 2 EMR光學量測結果及討論28
2.3. 3電流量測結果及討論29
2.3. 4電容量測結果及討論35
第三章 基本理論與模擬38
3.1 理論模型39
3.2 模擬結果與討論45
第四章 結論與展望49
第五章 參考文獻51
附錄一 程式原始檔53
附錄二 配向膜參數57

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