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研究生： 林進龍
Lin, Chin-Lung
論文名稱： 以幾何模型法估算溝槽面與液晶層間之表面方位角錨定能
Evaluation of surface azimuthal anchoring energy between grating surface and nematic liquid crystal layer using geometric model
指導教授： 陳鐵城
Chen, Tei-Chen
學位類別： 博士
Doctor
系所名稱： 工學院 - 機械工程學系
Department of Mechanical Engineering
論文出版年： 2017
畢業學年度： 105
語文別： 英文
論文頁數： 50
中文關鍵詞： 液晶 、方位角錨定能 、溝槽表面 、表面形貌 、幾何模型
外文關鍵詞： liquid crystal, azimuthal anchoring energy, grating surface, Berreman’s theory, surface topography, geometric model
相關次數： 點閱：108  下載：2 
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    • 由於液晶具有特殊的光電性質，使得其在許多領域中有無限的應用潛能，且幾乎所有的液晶元件均需做表面配向，而使液晶分子的排列方向一致，本文中只針對溝槽配向的機制做探討，由於長形的液晶分子會有沿著溝槽排列的傾向，因為液晶分子的長軸平行溝槽的時候，其形變最小且能量最低。所以溝槽面與液晶層間的作用機制是我們所感興趣的。
    本研究提出了一個簡單的幾何模型，用以估算液晶顯示器元件中的溝槽面與液晶層間之表面方位角錨定能。模型的參數可經由實驗數據或有限元素法模擬所得的結果確定，且該模型可用於預測具有不同週期、高度和形狀(包括正弦形、方形、V形和梯形)的溝槽之表面方位角錨定能。由結果顯示出表面方位角錨定能的預測和實驗數據之間存在良好的一致性。
    此外，在估算結果以及從Berreman表達式和有限元素法模擬獲得的結果之間也觀察到良好的一致性。整體來說，由實驗和數值結果得知，對於本研究中考慮的向列型液晶5CB，其表面方位角錨定能會隨著溝槽高度的增加以及溝槽週期的減小而增加。

    A simple geometric model is proposed for estimating the azimuthal anchoring energy between grating surface and nematic liquid crystal layer of a liquid crystal display (LCD) device as a function of the grating height and grating pitch. The model parameters are determined directly from experimental or finite element method (FEM) data, and the model is then used to predict the surface azimuthal anchoring energy for gratings with various pitches, heights and shapes (sinusoidal relief, rectangular, V-shaped and trapezoidal grating). It is shown that a good agreement exists between the predicted results for the surface azimuthal anchoring energy and the experimental data. Moreover, a good agreement is also observed between the estimated results and those obtained from Berreman’s expression and FEM simulations, respectively. A saturation tendency of the surface azimuthal anchoring energy is observed as the square of the grating height increases for all three calculation methods (i.e., Berreman’s model, FEM simulations and geometric model). Overall, the experimental and numerical results show that for the nematic liquid crystal considered in the present study (4-n-pentyl-4'-cyanobiphenyl (5CB)), the surface azimuthal anchoring energy increases with an increasing grating height or a reducing grating pitch.

    摘要 I Abstract II 誌謝 III Contents IV List of Tables V List of Figures VI Nomenclature VIII Chapter 1 Introduction 1 1.1 Motivation 1 1.2 Literature Review 3 1.3 Objectives of the Research 4 1.4 Organization of this work 5 Chapter 2 Theoretical Approach 6 2.1 Geometric Model 6 2.1.1 Sinusoidal Relief Grating 10 2.1.2 Rectangular Grating 12 2.1.3 V-shaped Grating 15 2.1.4 Trapezoidal Grating 17 Chapter 3 Application of Finite Element Method 21 3.1 Two-dimensional Model 21 3.2 Elastic Distortion Energy 22 Chapter 4 Results and Discussion 24 4.1 Sinusoidal Relief Grating 24 4.2 Rectangular Grating 30 4.3 V-shaped Grating 37 4.4 Trapezoidal Grating 38 Chapter 5 Conclusions and Future Work 41 5.1 Conclusions 41 5.2 Future Work 42 References 43 Vita 48

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