Addressing Techniques of Liquid Crystal Displays

Temkar N. Ruckmongathan, Raman Research Institute, Bangalore, India Dr. Ruckmongathan is a Senior Professor at the Raman Research Institute, Bangalore, India. He has over 30 years' experience of research and development in the area of addressing techniques for driving LCDs. Professor Ruckmongathan has authored approximately 50 publications on driving matrix LCD. He has 16 US and European patents.

Series Editor s Foreword xiii Acknowledgements xv 1 Introduction 1 2 Liquid Crystal Displays 3 2.1 Matrix Displays 3 2.2 Display Fonts and Formats 5 2.3 Liquid Crystals 8 2.4 Physical Properties of Liquid Crystals 9 2.5 Basics of Electro-optic Effects with Liquid Crystals 10 2.6 Twisted Nematic Effect 11 2.7 Super Twisted Nematic (STN)-LCD 13 2.8 STN-LCD with a 270 Twist (STN-270) 13 2.9 STN-LCD with a 180 Twist (STN-180) 14 2.10 In-plane Switching 14 2.11 Ferroelectric LCD (FLCD) 14 2.12 Summary 15 3 Review of Addressing Techniques 17 3.1 Addressing Techniques 17 3.2 Matrix Addressing 18 3.3 Nonlinear Characteristics 19 3.4 Cross-Talk in a Matrix LCD 21 3.5 Driving Matrix Displays 22 3.6 Bi-phase Addressing 23 3.7 Line-by-Line Addressing (LLA) 25 3.8 Half-Select Technique 27 3.9 Two-Third-Select Technique (TTST) 29 3.10 Selection Ratio (SR) and the Maximum Selection Ratio 30 3.11 Limitations of Matrix Addressing 37 3.12 Principle of Restricted Pattern Addressing 38 3.13 Pulse Coincidence Technique (PCT) 40 3.14 Pseudo Random Technique (PRT) 42 3.15 Restricted Pattern Addressing Technique (RPAT) 43 3.16 Addressing Technique for Dial Type Displays 47 3.17 Frame Frequency 47 3.18 Large Area Display 48 3.19 Dielectric Relaxation 48 3.20 Supply Voltage of Drivers 49 3.21 Nonuniformity Due to Resistance Mismatches 49 3.22 Need for Multiline Addressing Techniques 51 4 Binary Addressing 53 4.1 Principle 53 4.2 Binary Addressing Technique (BAT) 55 4.3 Analysis of the BAT 58 4.4 Practical Aspects of the BAT 66 4.5 Drivers for Driving the LCD with the BAT 69 5 Orthogonal Functions and Matrix Addressing 71 5.1 Orthogonal Functions 71 5.2 Multiplexing 78 5.3 Matrix Addressing 80 5.4 Line-by-Line Addressing 81 5.5 Multiline Addressing 82 5.6 Discussion 85 6 Active Addressing 87 6.1 Principle 87 6.2 Active Addressing Technique (AAT) 87 6.3 Summary 93 7 Hybrid Addressing 95 7.1 Principle 95 7.2 Hybrid Addressing Technique (HAT) 96 7.3 Analysis of the HAT 98 7.4 Drivers of the Hybrid Addressing Technique 103 7.5 Discussion 103 8 Improved Hybrid Addressing 105 8.1 Principle 105 8.2 Improved Hybrid Addressing Technique (IHAT) 106 8.3 Analysis of IHAT 108 8.4 Discussion 115 9 Improved Hybrid Addressing Special Case 3 119 9.1 Principle 119 9.2 Analysis 120 9.3 Summary 126 10 Improved Hybrid Addressing Special Case 4 127 10.1 Principle 127 10.2 Analysis 127 10.3 Summary 136 11 Sequency Addressing 137 11.1 Principle 137 11.2 Technique 137 11.3 Discussion 141 12 Restricted Pattern Addressing 145 12.1 Principle 145 12.2 Technique 145 12.3 Analysis 149 12.4 Summary 152 13 Review of Methods to Display Greyscales 153 13.1 Greyscales in Liquid Crystal Displays 153 13.2 Basics of Greyscale 153 13.3 Frame Modulation 155 13.4 Pulse Width Modulation 157 13.5 Row Pulse Height Modulation 157 13.6 Data Pulse Height Modulation 159 13.7 Summary 161 14 Amplitude Modulation 163 14.1 Principle 163 14.2 Amplitude Modulation Split Time Interval 164 14.3 Amplitude Modulation in Multiline Addressing 170 14.4 Pulse Height Modulation 172 14.5 Discussion 173 15 Successive Approximation 175 15.1 Principle 175 15.2 Technique 177 15.3 Analysis 179 15.4 Discussion 181 16 Cross-Pair Method 183 16.1 Principle 183 16.2 Technique 186 16.3 Analysis 187 16.4 Cross Pairing with Four Pairs of Data Voltages 190 16.5 Discussion 196 17 Wavelet-Based Addressing 197 17.1 Principle 197 17.2 Line-by-line Addressing with Wavelets 201 17.3 Analysis 207 17.4 Principle of Multiline Addressing with Wavelets 210 17.5 Technique 215 18 Bit Slice Addressing 223 18.1 Principle 224 18.2 Bit Slice Addressing Technique 229 18.3 Bit Slice Addressing with a Light Source 231 18.4 Bit Slice Addressing with Multiple Light Sources 232 18.5 Merits of Bit Slice Addressing 236 18.6 Demerits of Bit Slice Addressing 238 18.7 Discussion 239 19 Multibit Slice Addressing 241 19.1 Principle 241 19.2 Dual Bit Addressing of the LCD 242 19.3 Nibble Slice Addressing 246 19.4 Summary 248 20 Micro Pulse Width Modulation 249 20.1 Principle 249 20.2 Micro Pulse Width Modulation 250 20.3 Results 261 20.4 Summary 266 21 Comparison of Addressing Techniques 267 21.1 Line-by-Line Addressing 267 21.2 Multiline Addressing 268 21.3 Methods to Display Greyscales 271 21.4 Summary 272 22 Low Power Dissipation 273 22.1 Background 273 22.2 Principle 274 22.3 Multistep Waveform for Low Power 275 22.4 Static Drive with a Multistep Waveform 278 22.5 Power Dissipation in a Multiplexed Matrix LCD 278 22.6 Waveforms to Reduce Power Dissipation 281 22.7 Low Power Dissipation in the Successive Approximation Method 283 22.8 Summary 290 23 Low Power Consumption of Backlight 291 23.1 Principle of Backlight Switching 291 23.2 Reduction of Power with White Backlight and Monochrome Images 292 23.3 Power Reduction in the Colour Sequential Mode 300 23.4 Power Reduction of Backlight with Micro Pulse Width Modulation 300 23.5 Power Reduction with Micro PWM in the Colour Sequential Mode 304 23.6 Summary 308 24 Drivers for Liquid Crystal Displays 309 24.1 Basics 309 24.2 Drivers for Direct Drive 310 24.3 Drivers for the Matrix LCD 313 24.4 Drivers for Multiline Addressing Techniques 315 24.5 Summary 317 25 Active and Passive Matrix Addressing 319 25.1 Switched Passive Matrix Addressing (Line-by-Line) 319 25.2 Switched Passive Matrix Addressing (Line-by-Line) with Reduced External Connections 321 25.3 Multiplexed Active Matrix Addressing 322 25.4 An Ideal Active Matrix LCD 323 26 Conclusion 325 Bibliography 329 Index 333