Preface ................................................................. ix Acknowledgements ........................................................ xi Notations .............................................................. xvi 1 Overview ................................................................. 1 KOHKI TAKATOH 1.1 Development of the LCD Market ........................................ 1 1.2 Improvement of Viewing Angle Dependence of the Contrast Ratio ........ 2 1.3 Ferroelectric and Antiferroelectric Liquid Crystals .................. 2 1.4 Development of Novel Alignment Method ................................ 3 1.5 The Characteristics of this Book ..................................... 4 2 Rubbing Technologies: Mechanisms and Applications ........................ 7 MASAKI HASEGAWA 2.1 Introduction ......................................................... 7 2.2 Rubbing Mechanisms ................................................... 8 2.2.1 Observations of rubbed surfaces ................................ 8 2.2.2 Definition of rubbing strength ................................ 23 2.2.3 Alignment mechanisms .......................................... 30 2.2.4 Pretilt mechanisms ............................................ 32 2.3 Applications ........................................................ 36 2.3.1 Alignment defects of actual devices ........................... 36 2.3.2 Characteristics of the rubbing process ........................ 43 2.3.3 Alignment material ............................................ 47 3 Non-rubbing Methods ..................................................... 55 3.1 Introduction ........................................................ 55 MASAKI HASEGAWA 3.2 Photoalignment ...................................................... 57 MASAKI HASEGAWA 3.2.1 Introduction .................................................. 57 3.2.2 Overview ...................................................... 59 3.2.3 Photoalignment using polyimide ................................ 65 3.2.4 Influence of UV light on display device characteristics ....... 70 3.2.5 Light source .................................................. 72 3.2.6 Comparison of photoalignment and rubbing ...................... 73 3.2.7 Current status of photoalignment .............................. 75 3.3 Oblique Evaporation Method .......................................... 76 MASANORI SAKAMOTO 3.3.1 Alignment mechanism ........................................... 76 3.3.2 Evaporation apparatus ......................................... 78 3.3.3 Material scientific view point ................................ 78 3.4 Liquid Crystal Alignment on Microgroove Surfaces .................... 79 KOHKI TAKATOH 3.4.1 Liquid crystal alignment on microgroove surfaces .............. 79 3.4.2 Control of the pretilt direction by a "hybrid cell" ........... 79 3.4.3 Microgroove surface control of pretilt angle direction ........ 83 3.5 LB Membranes for the Alignment Layer ................................ 84 KOHKI TAKATOH 3.5.1 LB membranes for the alignment layer .......................... 84 3.5.2 Polyimide LB alignment film ................................... 85 3.5.3 Structure of polyimide LB films and liquid crystalline alignment on the film ......................................... 85 3.6 PTFE Drawn Films for Alignment Layers ............................... 87 KOHKI TAKATOH 3.7 Liquid Crystalline Alignment on Chemically Treated Surfaces ......... 89 KOHKI TAKATOH 3.7.1 Addition of surface active agents into liquid crystalline materials ..................................................... 90 3.7.2 Treatment of the substrate surface by active surface agents ... 90 4 Applications of Nematic Liquid Crystals ................................. 99 4.1 Summary of Molecular Alignment and Device Applications .............. 99 RAY HASEGAWA 4.1.1 Molecular alignment in nematic phases ......................... 99 4.1.2 Device applications .......................................... 102 4.2 Twisted Nematic (TN) ............................................... 102 RAY HASEGAWA 4.2.1 Basic operation .............................................. 103 4.2.2 OFF state .................................................... 104 4.2.3 ON state ..................................................... 105 4.2.4 Dynamic response ............................................. 105 4.2.5 Reverse domains .............................................. 106 4.3 Super Twisted Nematic (STN) ........................................ 106 NOBUYUKI ITOH 4.4 The IPS (In-Plane Switching) Mode .................................. 110 MITSUHIRO KODEN 4.5 Vertical Alignment (VA) Mode and Multi-domain Vertical Alignment (MVA) Mode ............................................... 111 KOHKI TAKATOH 4.5.1 Vertical alignment (VA) mode ................................. 111 4.5.2 MVA method (Multi-domain vertical alignment method) .......... 112 4.6 Pi Cell ............................................................ 117 MASAKI HASEGAWA 4.6.1 LC configuration ............................................. 118 4.6.2 Dynamics ..................................................... 120 4.7 Multi-domain Mode .................................................. 121 KOHKI TAKATOH 4.7.1 Improvement of the viewing angle dependence of TN-LCDs ....... 121 4.7.2 Mechanism of viewing angle dependence of TN-LCDs ............. 122 4.7.3 Reduction of the viewing angle dependence by the multi-domain mode ............................................ 123 4.7.4 Formation of two kinds of regions possessing different alignment directions in one pixel ............................ 125 4.7.5 Formation of two kinds of region with different pretilt angles in one pixel .......................................... 127 4.8 Polymer Dispersed Liquid Crystals (PDLC) ........................... 132 RAY HASEGAWA 5 Alignment Phenomena of Smectic Liquid Crystals ......................... 139 5.1 Layer Structure and Molecular Orientation of Ferroelectric Liquid Crystals .................................................... 139 NOBUYUKI ITOH 5.1.1 Introduction ................................................. 139 5.1.2 Ferroelectric SmC* liquid crystals ........................... 139 5.1.3 Surface-Stabilized Ferroelectric Liquid Crystals (SSFLCs) .... 141 5.1.4 Smectic layer structure study ................................ 142 5.1.5 Molecular orientational states and optical properties ........ 149 5.1.6 Summary ...................................................... 162 5.2 Alignment and Bistability of Ferroelectric Liquid Crystals ......... 163 KOHKI TAKATOH 5.2.1 Introduction ................................................. 163 5.2.2 Driving scheme of SSFLCs ..................................... 163 5.2.3 FLC materials for excellent alignment and bistability ........ 165 5.2.4 Polymer crystallinity, linearity and molecular structures .... 166 5.2.5 Polarity on polymer surfaces ................................. 172 5.2.6 Rubbing and annealing process ................................ 177 5.2.7 Electric double layer influence .............................. 179 6 Applications of Ferroelectric and Antiferroelectric Liquid Crystals ........................................................ 187 6.1 Molecular Orientations and Display Performance in FLC Displays ....................................................... 187 MITSUHIRO KODEN 6.1.1 Introduction ................................................. 187 6.1.2 The DHF mode ................................................. 188 6.1.3 The bookshelf orientation .................................... 189 6.1.4 C1-uniform (C1U) orientation ................................. 195 6.1.5 C2-uniform (C2U) orientation ................................. 197 6.1.6 Shock stability of FLC displays .............................. 202 6.1.7 The layer-rotation phenomenon ................................ 206 6.1.8 Summary ...................................................... 208 6.2 Alignment and Performance of AFLCD ................................. 209 KOHKI TAKATOH 6.2.1 AFLC materials and Devices ................................... 209 6.2.2 Alignment of AFLC ............................................ 212 6.2.3 Driving margin hysteresis and threshold properties ........... 216 6.3 Application of FLC/AFLC Materials to Active matrix Devices ......... 219 KOHKI TAKATOH 6.3.1 Introduction ................................................. 219 6.3.2 Specifications of liquid crystalline materials with spontaneous polarization for TFT driving ..................... 220 6.3.3 Active matrix driving for FLC or AFLC materials .............. 225 Index .................................................................... 257