《LCD驱动系统》PPT课件.ppt

液晶顯示器驅動系統講師:,課程大綱液晶物質簡介液晶的電光效應液晶基本驅動原理STN LCDs 驅動原理TFT LCDs 驅動原理影響TFT LCDs 畫面品質的因素Driver IC 簡介TFT LCDs 模組及介面技術簡介,液晶物質的相變化,固體結晶,液晶,液體,加熱,加熱,冷卻,冷卻,液晶分子的種類,液晶分子的排列,Crystalline,Liquid Crystalline,Liquid,K SmC SmA N L,Biaxial,Unaxial,Isotropic,Temperature,液晶的分類,液晶的電光特性,異向性(Anisotropic)排列因數()折射率()黏滯係數()介電係數()電導係數 磁化率彈性係數(),液晶的光學特性,Optical Positive,Optical Negative,Helical AxisOptical Axis,Optical Axis,液晶驅動原理,電極,電極,液晶,Field OFF,Field ON,液晶顯示器主要優缺點,優點低電壓驅動。低消耗電流。體積薄，重量輕。可實現大面積化。彩色化容易。缺點視角限制。外加被光源或投射光源。溫度操作範圍限制。,液晶顯示器的種類,液晶顯示器,扭轉型(Twinst Nematic,TN)1971超扭轉型(Super Twinst Nematic,STN)1984 雙層雙扭轉型(Double Layer STN,DSTN)1987 光相位補償超扭轉型(Film STN,FSTN)1988 主動驅動超扭轉型(AASTN or MLS STN)1992強介電型(Ferroelectric Liquid Crystal:FLC)1980PDLC(Polymer Dispersive LC)1988 PSCT(Polymer Stabilized Cholesteric Texture)1993Other DS(Dynamic Scattering)1968 PC(Phase Change)1968 GH(Guest Host)1968 ECB(Elcetrical Control Birefregency)1971BTN(Bistable Twist Nematic)1995IPS(In Plane Switch)1995VA(Vertical Alignment)1996,TN 型 LCDs 顯示原理,液晶分子,Field OFF,Field ON,利用液晶的旋光特性調變穿透光線,液晶的旋光特性消失,STN LCDs 顯示原理,液晶分子,Field OFF,利用液晶的雙折射特性調變穿透光線,TN&STN 電光轉移曲線V-T Curve,100%,90%,10%,VnsSTN,VsSTN,VsTN,VnsTN,T,V,TN 與 STN 的電壓漂移,T,100%,V,STN Mode,LCDs 驅動方式,直接驅動法(Direction Addressing)靜態驅動法(Static Addressing)多工驅動法(Multiplex Addressing)主動驅動法(Active Addressing/Multi-Line Selection)主動矩陣驅動法(Active Matrix Addressing)兩端元件(MIM,Diode.)三端元件(A-Si:H TFT,Ploy-Si TFT.)Plasma Addressing(PALC)熱掃描驅動法(雷射掃描)光掃描驅動法(電子速掃描,LCDs 靜態驅動法,Vsig,Vc,Vs,Vc-Vs,ON,OFF,多工驅動法(振幅選擇驅動法,APT),多工驅動法的限制,APT 驅動波形,IAPT 驅動波形,APT Addressing,IAPT Addressing,APT 與 IAPT 方式比較,APT AddressingLow Voltage Segment Driver:2DHigh Voltage Common Driver:2FIAPT AddressingOffset+D for Positive PolarityOffset+F for Negative PolarityVoltage Range of Segment Driver:F+DVoltage Range of Common Driver:F+D,高容量多工驅動的對策,STN LCDs 規格,Operation Voltage Vop:,Bias Ratio:,Steepness:,Selection Ratio:,STN LCDs 驅動電壓計算,If Voff=2V,N=240 rows,Then:,APT:Segment Driver:2.96V,Common Driver:44.40VIAPT:Segment&Common Drivers:23.68V,STN LCDs Drivers 架構,.移位暫存器(Shifter Register),DCLK,串列輸入訊號,.閂鎖暫存器(Latch Register),LP,F+D,0,F-D,2D,偏,壓,位,準,.,.,DF,(HLHL.H),.,H,L,H,H,並列輸出,垂直訊號電極,2D,0,2D,2D,IAPT 參考電壓,IAPT 驅動 IC,灰階顯示 FRC,Frame Rate Control,FRC:,灰階顯示 PWM,Pulse Width Modulation,PWM:,灰階顯示 PHM,Pulse High Modulation,PHM:,液晶的頻率響應,Vertical Crosstalk of STN LCDs,Vertical Crosstalk 的抑制(一),每兩條水平線變換一次驅動電壓極性,Vertical Crosstalk 的抑制(二),採用補償驅動週期,Vertical Crosstalk 的抑制(三),一條水平掃描線的掃描週期分割成兩部份，一半的掃描時間是採用正極性的驅動訊號，另一半的時間是採用負極性的驅動訊號。,Horizontal Crosstalk of STN LCDs,A,B,A,B,Horizontal Crosstalk 的抑制,A,B,Frame Response of STN LCDs,Active Addressing for STN LCDs,Active Addressing 驅動電壓,If Voff=2V,N=240 rows,Then:F=0.730 X 2V=1.460V|G|=0.954 X 2V=21.909VOutput Range of Segment Driver is about 44V.Common Driver of Common Driver is about 3V.,Segment Voltage of Active Addressing,Active Addressing 的矩陣運算,列向量（Column）,時間（Time）,行向量（Row）,Bit-Map Image Matrix,Row Function Matrix,時間（Time）,列（Column）,Column Voltage Matrix,矩陣運算方式,行（Row）,行向量（Row）,列向量（Column）,Bit-Map Image Matrix,Row Vector,時間（Time）,列（Column）,Time=Dtk,行向量（Row）,列向量（Column）,第j列,Row Function Matrix,時間（Time）,列（Column）,Column Vector,垂直序列運算Column Sequential,時間序列運算Time Sequential,Column Sequential 硬體架構,Time Sequential 硬體架構,主動矩陣式液晶顯示器AM-LCDs,TFT LCDs 等效電路,Row Drivers,Column Driver,Arrangement of Color Filter,Stripe,Triangle,Pixel Structure of TFT LCDs,Cs on Common 與 Cs on Gate 架構,Timing Chart of TFT LCDs,Frame Time,Gate123N,Time,TFT LCDs Driving Method,Column Inversion,Dot Inversion,Row Inversion,Frame Inversion,Direct Driving of TFT LCDs,DC Bias of Common,GrayScale Voltage,AC Modulation Addressing of TFT LCDs,Common Waveform,Graylevel Voltage,1Frame/1 Line,TFT LCDs 的電光效應Direct Addressing,TFT LCDs 的電光效應AC Addressing,TFT LCDs Driving Waveform Cs on Common(一),TFT LCD 驅動波形(Cs on Common,Common=DC Bias),TFT LCDs Driving Waveform Cs on Common(二),TFT LCDs Driving Waveform Cs on Gate,TFT 電容效應的影響,液晶電容的效應,液晶電容 CLC 會隨液晶作用電壓的改變而變化，因此在驅動液晶時會有殘存的 DC 成份，其所造成的影響：Image Sticking.Picture Flicker.液晶作用電壓大時，液晶分子趨向平行電場方向排列：液晶作用電場小時，液晶分子趨向垂直電場方向排列：,二階驅動方式的效應,Cs,Clc,Cgd,Csd,Cgs,Vct,Ch(N-1),Ch(N),Vs,垂直影像訊號,水平掃描訊號,Vg,水平掃描訊號,Vg,TFT 補償驅動法,3 Level Addressing,4 Level Addressing,3 Level Addressing,4 Level Addressing,Vst=Vct,B(+),B(-),B(-),B(+),W(+),W(+),W(-),W(-),B(+),W(-),B(-),W(+),Vp(+),Vp(-),Vp=CgdVghl/Ct,CsVge(-)/Ct,CsVge(+)/Ct,正極性,負極性,正極性,負極性,Ct=Cs+Clc+Cgd,Cs on Gate 電壓補償方式,Comparsion of Addressing Method,Horizontal Line Crosstalk,A,B,Csc,Csc,Csc,TFT Substrate,Color Filter Substrate,Horizontal Area Crosstalk,A,B,Vertical Area Crosstalk,Shading Crosstalk,Shading Crosstalk 的抑制,Gate Pulse 的傳遞延遲,Gate(Scan)Line 的等效阻抗為一連串的串聯 RC 網路，因此 Gate Pulse 在傳遞時會造成波形的傳遞延遲失真。,液晶畫素邊際電場效應(一),Reverse Tilt,畫素電極,鄰近電極,共通電極,VP,VL,VA,VA VL:Disclination DisappearedVP LC Threshold Voltage,Reverse Tilt,液晶畫素邊際電場效應(二),改善方法1.增加液晶分子的 預傾角(Pretilt Angle)2.增加 Black Mask 的 遮蔽面積,驅動 IC Scan Driver,Bidirectional Shift Register,Level Shift Circuit,Output Buffer,G1 G2 G3.,STVR,STVL,CPV,R/L,VDDD,VSSD,VDDA,VSSA,STVR,STVL,G1,G2,Gx,Serial In Serial Out Analog Data Driver,Multiplexer,Pro:Very simple.Fewer external connections.Con:Many analog inputs.Reduced pixel charging time.System Note:Sample clock:(Dot clock)/N,N Phases.Video Phase:N,Variation on MultiplexerPro:Video Input.Con:Fast data line charging needed.Reduced pixel charging time.System Note:Shift Clock:(Dot Clock)/3 for Mono.Video Phase:3 for Mono.,Sample and Hold,Serial In Parallel OutAnalog Data Driver(一),Serial In Parallel OutAnalog Data Driver(二),Double Sample and Hold/Multi-Phase,Por:Reduced operation frequency.System Note:Video In:NVideo Phase:NShift Clock:(Dot Clock)/N.,Digital Data Driver(一),Digital-to-analog Converters,Por:Digital input.Con:Complex.Requires sufficient precision to correct for LC response variation.,Ramp In,Sampled Ramp,Por:Digital input.Programmable ramp.Con:Complex circuit.High speed digital circuits.Reduced pixel charging time.,Digital Data Driver(二),1-of-n Selector,Simple DACPro:Digital input.Programmable external voltages.Con:Complex circuit.High speed digital circuits.Many pass gates per data line.,Digital Data Driver(三),All Digital Circuit,Gamma Correction of LCD,Analog Correction:2 3 Segment Approach.Digital Correction:External fixed voltage.,Gamma Correction Simple Case,Transmission,Voltage,The Block Diagram of the TFT LCD Module,The TFT LCD Module Type,Classified into two kinds by data driverAnalog type TFT-LCD moduleThe analog data driversThe analog interface to PCOnly NECDigital type TFT-LCD moduleThe digital data driversThe ADC/LVDS/PanelLink interface to PCMainstream,The Analog Interface,The ADC Interface,The LVDS/PanelLink Interface,Analog/ADC/LVDS/PanelLink,Analog InterfaceTrue ColorSampling Error Low Edge SharpnessNoise in the Analog Signal Transmission,Analog/ADC/LVDS/PanelLink,ADC InterfaceMainstream in the Desktop LCD Monitor InterfaceSampling Error Low Edge SharpnessNoise in the Analog Signal TransmissionEMI Issue for High Resolution FormatLow Image Quality and High Cost,Analog/ADC/LVDS/PanelLink,LVDS InterfaceMainstream in the Notebook PC InterfaceHigh Edge SharpnessReducing EMI&Number of Cable LineHigh Image Quality and Low CostShort Transmission Length&Low Noise MarginCompatible Issue,PanelLink InterfaceApplication in the Desktop LCD Monitor InterfaceHigh Edge SharpnessReducing EMI&Number of Cable LineHigh Image Quality and Low CostSecond Supply Source Issue,Analog/ADC/LVDS/PanelLink,TFT Module 設計考慮(一),顯示的影像訊號時序規格(Image Format)圖框重複率(Frame Rate)水平掃描線掃描時間TFT 的 ION/IOFF 電流水平掃描脈線的RC時間常數灰階誤差直流漂移,TFT Module 設計考慮(二),選擇適合的驅動方式(Cs on Gate or COM)選擇適合的極性轉換方式驅動IC(Scan&Source)的選取TFT LCDs 模組介面技術的選擇,大面積高解析度 TFT LCDs 的開口率影響因素,Plasma Addressing LCDs,In-Plane-Switch Mode LCDs,Vertical Alignment Mode LCDs,未加電場OFF 狀態,施加電場ON 狀態,入射光,偏光板,液晶分子,玻璃基板,出射光之極化狀態,解偏板,出射光,Comparison of Liquid Crystal Modes,Slightly dependent on viewing angle,廣視角,液晶反應速度慢,Off(Black)On(White),畫面對比低,畫面品質差,TN,IPS,VA,