LCD introduction1.ppt

Liquid Crystal Displays Introduction Presented by Henry Wu Oct. 28, 2004 The Order Parameter LCD : 一種光電顯示裝置 藉由改變電壓(VLC)來控制光通過的量,可以將video信號(電)轉換成亮暗顯示(光) Color LCD Panel 基本元件 Color LCD 顯示原理 Direct/Multiplex LCD 基本構造 Passive/Active Matrix LCD 基本構造 Passive/Active Matrix LCD Driving Structure TFT LCD Panel 技術 TFT LCD Panel Structure TFT LCDs 的電光效應Direct Addressing (Vcom Constant) TFT I-V 特性 TFT 電容效應的影響 TFT 電容效應的影響 TFT Feedthrough Effect - 補償驅動法 TFT Feedthrough Effect - Cs on Gate 電壓補償方式 Simple Matrix Common Drive Circuit Simple Matrix Segment Drive Circuit 振幅選擇驅動法(APT) Optimization of Amplitude Selection Since the optical response is determined by the rms voltage across the pixel, it is advantageous to make the selection ratio, on/off, as large as possible Optimization of Amplitude Selection APT/IAPT Waveform Comparison STN LCD 驅動電壓 (APT/IAPT) Signals of LCD Driver Hi-FAS Design for STN Driver Morphing STN into TFT TFT advantages over STN ... TFT transistors isolate Source Line signals to only the intended pixel rows, and block them from other rows. Gate line shape and accuracy is not very critical (VON/VOFF – 1) of TN has 5~8x wider ratio than STN = Shading step size can be much bigger S/H architecture supports fast LC material well What STN controller faces ... No active device to “isolate” row from row = the SEG switching distortion must be minimized Pixel voltage is determined by both Column (SEG) and Row (COM) = Distortion in both pixel electrodes will show up as crosstalk VON/VOFF of STN is 5~8x smaller than TN = Shading step size error tolerance is very small Video rate Liquid Crystal requires very fast refresh rateto avoid “frame response” Active Matrix OLED LCD Introduction LCD Driving Scheme TFT LCD Driver STN LCD Driver Future of LCD OUTLINE Aspect Ratio of LTPS and α-TFT Larger Aspect Ratio due to Smaller TFT area in LTPS. TFT LCD Driver Waveform 因為Gate Driver IC負責每列電晶體的開關，所以又稱為Row Driver或Scan Driver。當Gate Driver逐列動作時，Source Driver IC負責在每一列中將資料