臺灣博碩士論文加值系統

光學響應時間太慢是目前液晶光學元件的主要瓶頸，除了p-cell（或OCB-cell）外一般液晶顯示器（LCD）無法達到動畫顯示需求（響應時間<16.7豪秒），如典型TN TFT-LCD的響應時間為30~50豪秒。雖然 p-cell在bend state下具快速光學響應，但讓其轉變到Bend state耗時數分鐘，且bend state在低電壓下並不穩定，使得p-cell一直無法實用。利用實驗和理論推演計算，我們深入且完整的研究p-cell及3p/2-cell的快速響應機制，並且設計了一個具快速光學響應且穩定的twisted p-cell，也進一步提昇3p/2-cell的光學響應速度。另外我們也解釋了光學響應較慢的VA-90°， VA-180°以及VA-270°液晶元件的機制。

Liquid crystal devices have been widely used in our daily life, however the drawback of slow response limits the application of liquid crystal devices (such as true video-rate TV). Recently, the p-cell or OCB-cell had drawn consideration. However, the bend state of p-cell is not stable at low voltage. Therefore it takes a long warm-up time before working this cell and there are domains emerge between the pixels to damage the image quality when working it. We investigated the fast-response mechanism of p-cell and 3p/2-cell in detail. And designed a twisted p-cell witch possesses fast optical response as p-cell but without the unstable problem. We also improved the optical response of 3p/2-cell to 2.0 ms. Finally we explained the slow response mechanism of VA-90°, VA-180° and VA-270°.

Contents
Chinese abstract (摘要) i
Abstract iv
Chinese acknowledgements (致謝) vii
Acknowledgements viii
Contents ix
List of figures xiii
List of tables xxv
List of symbols xxvii
Chapter 1 Introduction 1
1.1 Typically liquid crystal devices 2
1.2 Properties of liquid crystal 5
1.3 Jones matrix method 11
1.4 Estimate of response time in the pure rotational system 15
1.5 Influence of the flow effect on the dynamics of liquid crystal devices 17
1.6 Definition of optical response time 18
References of chapter 1 21
Chapter 2 Dynamic theory and numerical calculation 23
2.1 Dynamic theory 23
2.1.2 Continuous theory of liquid crystal 23
2.1.2 Static director distribution-“Euler-Lagrange equation” 24
2.1.3 Dynamic theory-“Erickson-Leslie theory” 27
2.1.4 Dynamic deformation equation ignore the flow effect 30
2.1.5 1-D Dynamic deformation equations 31
2.1.6 The relation of viscous coefficients 32
2.2. Numerical calculation 33
2.2.1 1-D dynamic equations 33
2.2.2 The numerical method 34
References of chapter 2 40
Chapter 3 Dynamics of p-cell liquid crystal devices 41
3.1 Sample preparation and measured method 42
3.2 State transition of p-cells 46
3.3 Electro-optical properties 51
3.4 Dynamic properties 54
3.5 Simulated results 58
3.6 Conclusion 62
References of chapter 3 63
Chapter 4 Experimental method and results of the fast optical response twisted nematic liquid crystal p-cells 65
4.1 Sample preparation 65
4.2 Measurement method of alignment layer thickness 72
4.3 Measurement method of pretilt angle 72
4.4 Measurement method of phase retardation and cell gap 74
4.5 Experimental results of electro-optical properties 75
4.6 Summary of the experimental results 83
References of chapter 4 84
Chapter 5 Numerical calculation and results of the fast optical response twisted nematic liquid crystal p-cells 85
5.1 Numerical calculation 85
5.2 Calculated results 89
5.3 Corresponding director distribution 89
5.3.1 Director distribution in the optical rising process 91
5.3.2 Director distribution in the optical decay process 95
5.4 Transient flow velocity distribution 98
5.5 Summary of the calculated results 103
References of chapter 5 104
Chapter 6 Dynamic mechanism and application consideration of the fast optical response twisted nematic liquid crystal p-cells 105
6.1 Analysis of dynamic mechanism 106
6.1.1 Dynamic mechanism in the optical rising process 106
6.1.2 Dynamic mechanism in the optical decay process 112
6.2 Consideration of application 115
6.3 Conclusion 116
References of chapters 6 116
Chapter 7 Optical response of the super twisted nematic liquid-crystal 3p/2 cells 117
7.1 Introduction 117
7.2 Experiment 118
7.3 Calculated results and theoretical analysis 125
7.4 Further improvement on the optical response 134
7.5 Conclusion 134
References of chapter 7 139
Chapter 8 Dynamics of the vertical-alignment liquid crystal modes 141
8.1 Introduction 141
8.2 Experiment 143
8.2.1 Experimental results of VA-90° Lcell 145
8.2.2 Experimental results of VA-180° Lcell 145
8.2.3 Experimental results of VA-270° Lcell 148
8.3 Simulation 150
8.3.1 Calculated results of VA-90° Lcell 151
8.3.2 Calculated results of VA-180° Lcell 157
8.3.3 Calculated results of VA-270° Lcell 162
8.4 Discussion and conclusion 166
References of chapter 8 169
Chapter 9 Conclusion

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