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1、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2021/9/211液晶物質的相變化固體結晶液晶液體加熱加熱冷卻冷卻2021/9/212液晶分子的種類Smectic LC 層狀液晶Nematic LC 線狀液晶Cholesteric LC膽固醇狀液晶2021/9/213液晶分子的排列CrystallineLiquid CrystallineLiquid K SmC SmA N LBiaxialUnaxialIsotropi
2、cTemperature2021/9/214液晶的分類2021/9/215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()2021/9/216液晶的光學特性Optical PositiveOptical NegativeHelical AxisOptical AxisOptical Axis2021/9/217液晶驅動原理電極電極液晶Field OFFField ON2021/9/218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
3、圍限制。2021/9/219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)
4、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)19962021/9/2110TN 型 LCDs 顯示原理Twist 90液晶分子Field OFFField 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2021/9/2111STN LCDs 顯示原理
5、Twist 270液晶分子Field OFFField ON利用液晶的雙折射特性調變穿透光線2021/9/2112TN&STN 電光轉移曲線V-T Curve100%90%10%VnsSTN VsSTNVsTNVnsTNTV2021/9/2113TN 與 STN 的電壓漂移T100%VTN ModeT100%VSTN Mode2021/9/2114LCDs 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 Sel
6、ection)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2021/9/2115LCDs 靜態驅動法LC CellXORVsVcVsigVcVsigVcVsVc-VsONOFF2021/9/2116多工驅動法(振幅選擇驅動法,APT)1 2 3 4N 1 2 3Frame 1Frame 2F0DT水平掃描訊號+D-D0垂直影像訊號Row 1Row 2Row 3Row NColumn 1ONO
7、FFONOFFF+DF-DF+DF-D+D-D0+D-D0+D-D0+D-D01 2 3 4NFrame 1液晶畫素電壓T2021/9/2117多工驅動法的限制1.01.11.21.31002002021/9/2118APT 驅動波形2021/9/2119IAPT 驅動波形APT AddressingIAPT Addressing2021/9/2120APT 與 IAPT 方式比較APT AddressingLow Voltage Segment Driver:2DHigh Voltage Common Driver:2FIAPT AddressingOffset+D for Positive
8、 PolarityOffset+F for Negative PolarityVoltage Range of Segment Driver:F+DVoltage Range of Common Driver:F+D2021/9/2121高容量多工驅動的對策(a)(b)(c)(d)(e)2021/9/2122STN LCDs 規格Operation Voltage Vop:Bias Ratio:Steepness:Selection Ratio:2021/9/2123STN LCDs 驅動電壓計算If Voff=2V,N=240 rows,Then:APT:Segment Driver:2.9
9、6V,Common Driver:44.40VIAPT:Segment&Common Drivers:23.68V2021/9/2124STN 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)LPF+D 0F-D 2D偏壓位準.DF(HLHL.H).HLHH並列輸出垂直訊號電極2D 02D2DIAPT 參考電壓IAPT 驅動 IC2021/9/2125灰階顯示 FRCFrame Rate Control,FRC:2021/9/2126灰階顯示 PWMPulse Width Modulation,PWM
10、:2021/9/2127灰階顯示 PHMPulse High Modulation,PHM:2021/9/2128液晶的頻率響應2021/9/2129Vertical Crosstalk of STN LCDs2021/9/2130Vertical Crosstalk 的抑制(一)每兩條水平線變換一次驅動電壓極性2021/9/2131Vertical Crosstalk 的抑制(二)採用補償驅動週期2021/9/2132Vertical 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。2021/9/
11、2133Horizontal Crosstalk of STN LCDs垂直驅動訊號L Line水平掃描波形液晶畫素波形(a)(b)(c)(d)ABABL2021/9/2134Horizontal Crosstalk 的抑制垂直驅動訊號L Line水平掃描波形液晶畫素波形(a)(b)(c)(d)傳統驅動方式水平掃描補償波形補償之液晶畫素波形(e)(f)GVLAB2021/9/2135Frame Response of STN LCDs2021/9/2136Active Addressing for STN LCDs2021/9/2137Active Addressing 驅動電壓If Voff
12、=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.2021/9/2138Segment Voltage of Active Addressing2021/9/2139Active Addressing 的矩陣運算列向量（Column）時間（Time）行向量（Row）Bit-Map Image MatrixRow Function Matrix時間（T
13、ime）列（Column）Column Voltage Matrix2021/9/2140矩陣運算方式行（Row）行向量（Row）列向量（Column）Bit-Map Image MatrixRow 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 Sequential2021/9/2141Column Sequential 硬體架構 NM圖框記憶體 NM圖框記憶體影像資訊
14、輸入IjNXOR陣列N加法邏輯陣列NM STN LCDs液晶層間隙4.5um液晶材料：低黏滯係數水平驅動函數唯讀記憶體Row Function ROMNSTN LCDs垂直驅動晶片TFT LCDs 垂直驅動晶片1轉2多工器2轉1解多工器2021/9/2142Time Sequential 硬體架構 NM圖框記憶體 NM圖框記憶體影像資訊 輸入IjNXOR陣列N加法邏輯陣列水平驅動函數唯讀記憶體Row Function ROMN1轉2多工器2轉1解多工器NM圖框緩衝記憶體NM圖框緩衝記憶體NM STN LCDs液晶層間隙4.5um液晶材料：低黏滯係數STN LCDs垂直驅動晶片TFT LCDs
15、垂直驅動晶片N2021/9/2143主動矩陣式液晶顯示器AM-LCDs2021/9/2144TFT LCDs 等效電路Row DriversColumn Driver2021/9/2145Arrangement of Color Filter R G B R G BR G B R G BR G B R G BRBG RGBRBGRBG RGBRBGRBG RGBRBGRGGBRGGBRGGBRGGBRGW BRGW BRGW BRGW BStripe Triangle 2021/9/2146Pixel Structure of TFT LCDs2021/9/2147Cs on Common 與
16、 Cs on Gate 架構液晶畫素TFTGate LineData LineCsCs液晶畫素TFTCommonCommonGate LineData LineCsCs Cs on CommonCs on Gate2021/9/2148Timing Chart of TFT LCDsFrame TimeGate123NTime2021/9/2149TFT LCDs Driving MethodColumn InversionDot InversionRow InversionFrame Inversion2021/9/2150Direct Driving of TFT LCDs DC Bias
17、 of CommonGrayScale Voltage V0V1V2V3V4V5V6V7V7V6V5V4V3V2V1V01 Frame/1 Line2021/9/2151AC Modulation Addressing of TFT LCDsV0V1V2V3V4V5V6V7V7V6V5V4V3V2V1V0Common WaveformGraylevel Voltage1Frame/1 Line2021/9/2152TFT LCDs 的電光效應Direct Addressing2021/9/2153TFT LCDs 的電光效應AC Addressing2021/9/2154TFT LCDs Dr
18、iving Waveform Cs on Common(一)TFT LCD 驅動波形(Cs on Common,Common=DC Bias)2021/9/2155TFT LCDs Driving Waveform Cs on Common(二)2021/9/2156TFT LCDs Driving Waveform Cs on Gate 2021/9/2157TFT 電容效應的影響PixelCgdCgsCsdCsdbCsdb2021/9/2158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.
19、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：2021/9/2159二階驅動方式的效應CsClcCgdCsdCgsVctCh(N-1)Ch(N)Vs垂直影像訊號水平掃描訊號Vg水平掃描訊號VgVshVslVstVthVth正極性驅動負極性驅動負極性驅動正極性驅動資料驅動晶片輸出訊號電位液晶畫素電位Vct=Vst-VpVpBlack(+)White(+)White(+)Black(+)Black(-)Black(-)White(-)White(-)2021/9/2160TFT 補償驅動法Ch(N-1)Ch(N)Vs
20、t=Vct影像訊號波形 Vs水平脈波掃描波形VgeVgeVghlCh(N-1)Ch(N)Vst影像訊號波形VsVge(+)Vge(-)VghlVghl3 Level Addressing4 Level Addressing2021/9/21613 Level AddressingB(+)W(-)B(-)W(+)正極性負極性Vst=VctB(+)B(-)W(+)W(-)B(+)W(-)B(-)W(+)Vp=CgdVghl/Ct正極性負極性正極性Ct=Cs+Clc+Cgd負極性CsVge/CtCsVge/Ct2021/9/21624 Level AddressingVst=VctB(+)B(-)B
21、(-)B(+)W(+)W(+)W(-)W(-)B(+)W(-)B(-)W(+)Vp(+)Vp(-)Vp=CgdVghl/CtCsVge(-)/CtCsVge(+)/Ct正極性負極性正極性負極性Ct=Cs+Clc+Cgd2021/9/2163Cs on Gate 電壓補償方式經由 Cs 將前一條水平脈波的補償波形耦合到動作的液晶畫素,補償 Cgd 造成的電壓漂移及改善液晶畫素內的直流電電壓殘餘.經由 TFT 的 Cgd 造成的電壓漂移經由 TFT 的 Cgd 造成的電壓漂移2021/9/2164Comparsion of Addressing Method2021/9/2165Horizonta
22、l Line CrosstalkABCscCscCscTFT SubstrateColor Filter Substrate2021/9/2166Horizontal Area CrosstalkAB2021/9/2167Vertical Area CrosstalkUpLowUpLow2021/9/2168Shading Crosstalk2021/9/2169Shading Crosstalk 的抑制2021/9/2170Gate 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。RCRC
23、RCRCN2021/9/2171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VPVLVAVA VL:Disclination DisappearedVP LC Threshold VoltageReverse Tilt 2021/9/2172液晶畫素邊際電場效應(二)TFT水平驅動電極垂直驅動電極RubbingDirectionDisclinationLineReverse TiltDomain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2021/9/2173驅動 IC Scan DriverBidi
24、rectional Shift RegisterLevel Shift CircuitOutput BufferG1 G2 G3.STVRSTVLCPVR/LVDDDVSSDVDDAVSSASTVRSTVLG1G2Gx2021/9/2174Serial In Serial Out Analog Data DriverSelectData jData j+1MultiplexerPro:Very simple.Fewer external connections.Con:Many analog inputs.Reduced pixel charging time.System Note:Samp
25、le clock:(Dot clock)/N,N Phases.Video Phase:NShift RegisterVideo InQiQi+1Variation 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 Hold2021/9/2175Serial In Parallel OutAnalog
26、 Data Driver(一)Shift RegisterQiQi+1Qi+2Qi+3Video InTransferDouble Sample and Hold/Single PhaseSample NSample N+1Sample N+2TTTNN+1N+2Out N-1Out NOut N+1Pro:Video Input.Small load on fast sample-and-holds.Full line time to charge pixel.Con:Complex analog circuit.Physical size.System Note:Shift Clock:D
27、ot Clock.Video Phase:Single Phase.2021/9/2176Serial In Parallel OutAnalog Data Driver(二)Shift RegisterQiQi+1Video InTransferDouble Sample and Hold/Multi-PhasePor:Reduced operation frequency.System Note:Video In:NVideo Phase:NShift Clock:(Dot Clock)/N.2021/9/2177Digital Data Driver(一)Shift RegisterDA
28、CDACDACDACDAC Serial Data BusDigital-to-analog ConvertersPor:Digital input.Con:Complex.Requires sufficient precision to correct for LC response variation.Shift RegisterCount Count Count Count CountRamp InSampled RampPor:Digital input.Programmable ramp.Con:Complex circuit.High speed digital circuits.
29、Reduced pixel charging time.2021/9/2178Digital Data Driver(二)Shift RegisterDecodeDecodeExternal Fixed voltages1-of-n SelectorSimple DACPro:Digital input.Programmable external voltages.Con:Complex circuit.High speed digital circuits.Many pass gates per data line.2021/9/2179Digital Data Driver(三)All D
30、igital Circuit 2021/9/2180Gamma Correction of LCDXY取像元件取像電路顯像電路顯像元件攝像機測受像機測Analog Correction:2 3 Segment Approach.Digital Correction:External fixed voltage.2021/9/2181Gamma Correction Simple CaseXY取像元件取像電路顯像電路顯像元件攝像機測受像機測TransmissionVoltage2021/9/2182The Block Diagram of the TFT LCD ModuleCCFL Backl
31、ightTFT-LCDPANELTiming ControllerScan DriverData DriverRGBCLKHsxVsxTFTLCD Module2021/9/2183The TFT LCD Module TypeClassified 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
32、/PanelLink interface to PCMainstream2021/9/2184The Analog InterfaceGraphicsControllerTFT-LCDPANELTiming ControllerScan DriverAnalog Data DriverHsVsAnalogRGBAnalogRGBCLKHsxVsxPreAmpLevelShifterControllerPLLPCAnalog ModuleTFTLCD ModuleOSDCCFL Backlight2021/9/2185The ADC InterfaceGraphicsControllerTFT-
33、LCDPANELTiming ControllerScan DriverDigital Data DriverHsVsAnalogRGBDigitalRGBCLKHsxVsxADCBufferControllerPLLPCADC ModuleTFTLCD ModuleOSDCCFL Backlight2021/9/2186The LVDS/PanelLink InterfaceGraphicsControllerLVDS/PanelLinkTxLVDS/PanelLinkRxTFT-LCDPANELTiming ControllerScan DriverCABLEClockHsVsDigita
34、lRGBDigitalRGBClockHsVsPCTFT-LCD ModuleDigital Data DriverCCFL Backlight2021/9/2187Analog/ADC/LVDS/PanelLinkAnalog InterfaceTrue ColorSampling Error Low Edge SharpnessNoise in the Analog Signal Transmission2021/9/2188Analog/ADC/LVDS/PanelLinkADC InterfaceMainstream in the Desktop LCD Monitor Interfa
35、ceSampling Error Low Edge SharpnessNoise in the Analog Signal TransmissionEMI Issue for High Resolution FormatLow Image Quality and High Cost2021/9/2189Analog/ADC/LVDS/PanelLinkLVDS InterfaceMainstream in the Notebook PC InterfaceHigh Edge SharpnessReducing EMI&Number of Cable LineHigh Image Quality
36、 and Low CostShort Transmission Length&Low Noise MarginCompatible Issue2021/9/2190PanelLink InterfaceApplication in the Desktop LCD Monitor InterfaceHigh Edge SharpnessReducing EMI&Number of Cable LineHigh Image Quality and Low CostSecond Supply Source IssueAnalog/ADC/LVDS/PanelLink2021/9/2191TFT Mo
37、dule 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2021/9/2192TFT 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2021/9/2193大面積高解析度 TFT LCDs 的開口率影響因素大尺寸面積增加水平驅動電極阻值增加水平驅動波形的時間常數增加水平掃描線減少液晶畫素的有效充放電時間增加解析度增加
38、Cgd/CLC的比值增加 Vgd 增加 Reverse Tilt Domain 與畫素面積的比例增加 Black Matrix 的遮蔽面積降低畫面品質增加水平驅動電極的寬度增加 TFT 的尺寸增加儲存電容 CS 的面積降低開口率2021/9/2194Plasma Addressing LCDsCathode-200VAnode0-200Negative ClowPositive ColumnFaraday DarkCathodeAnode-200V VirtualConnectionSamplingCapacitorAnalogSignal2021/9/2195In-Plane-Switch
39、Mode LCDs偏光版解偏版液晶分子作用電極玻璃基板入射光作用電場方向出射光之極化狀態 未加電場OFF 狀態 施加電場ON 狀態出射光2021/9/2196Vertical 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2021/9/2197Comparison of Liquid Crystal ModesStrongly dependent on viewing angle低驅動電壓視角窄小Off(White)On(Black)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Slightly dependent on viewing angle畫面對比高廣視角Off(Black)On(White)液晶反應速度快彩色畫面顯像佳TNIPSVA2021/9/2198