TFT驱动原理介绍

TFT驅動原理介紹©ChiMeiOptoelectronicsPDD1/PD2Page2大綱圖像顯示原理LCD基本驅動方式驅動系統架構及組成LCD驅動方式的應用©ChiMeiOptoelectronicsPDD1/PD2Page3圖像顯示原理©ChiMeiOptoelectronicsPDD1/PD2Page4圖像組成dotPixel1pixel=3dot(sub-pixel)©ChiMeiOptoelectronicsPDD1/PD2Page5混色效果用RGB三種顏色光的亮暗比例可混出無數種顏色三角形越大所能顯示的顏色越豐富©ChiMeiOptoelectronicsPDD1/PD2Page6ColorDepthRedGreenBlueWhiteGrayScale0816243240485663Forcolordepth8bitsThereare28x28x28=16,777,216colorsForcolordepth6bits,Thereare26x26x26=262,144colorsWhatisthedifference?©ChiMeiOptoelectronicsPDD1/PD2Page7Truecolor256colorColorDepth©ChiMeiOptoelectronicsPDD1/PD2Page8圖像顯示原理--小結圖案由Pixel組成Pixel由RGBdot組成眼睛有混色效果分別控制RGBdot亮度自由組成各種圖案©ChiMeiOptoelectronicsPDD1/PD2Page9LCD基本驅動方式©ChiMeiOptoelectronicsPDD1/PD2Page10LCD如何控制亮度以90度TN為例資料來源：SHARP’swebsite©ChiMeiOptoelectronicsPDD1/PD2Page11光源垂直偏光板玻璃電極玻璃電極液晶水平偏光板EGDSLCD如何控制亮度CLC©ChiMeiOptoelectronicsPDD1/PD2Page12TFTWhatkindoffunctiondoesTFTplay?VgVdVsTFTCLCCSTWrite&HoldThinkasaswitch!!!GDSGDS©ChiMeiOptoelectronicsPDD1/PD2Page13TFTLCD驅動原理架構©ChiMeiOptoelectronicsPDD1/PD2Page14•不同壓差有不同穿透率•相同壓差，不同極性的電壓穿透率差不多•為了避免液晶極化，需以AC電壓操作Transmittance(%)穿透率(Vcom)(Vs)Voltage(Vs-Vcom)0©ChiMeiOptoelectronicsPDD1/PD2Page15TFT-LCD的穿透率：TFT-LCD面板的宿命：光学穿透率不佳。開口率：液晶分子中光線能透過的有效區域的比例。即液晶分子中有效的透光區域與全部面積的比例，就稱之爲開口率。100%開口率=B/A*100%AB©ChiMeiOptoelectronicsPDD1/PD2Page16光学穿透率不佳原因：1，TFT的开口率：约60%以上。2，CF的滤光效率：约1/3以下。3，偏光板的极化效率（含两片吸收）：约40%上下。三項相乘60%×1/3×40%約為8%所以，在TFTLCD的設計中，要盡量提高開口率，因爲只有提高開口率，便可以增加亮度，而同時背光板的亮度也不用那麽高，可以節省耗電及花費。©ChiMeiOptoelectronicsPDD1/PD2Page17Line-by-lineDisplay©ChiMeiOptoelectronicsPDD1/PD2Page18TimingofChargingGDSDatalineVcomClcCstCgsVdVsVcomVgVdVsΔVVghVgl1line1frameΔV©ChiMeiOptoelectronicsPDD1/PD2Page19FeedThroughGDSDatalineScanlineVstVcomClcCstCgsVgVdVsΔV=(Vgh-Vgl)•Cgs+Cst+ClcCgsVgh-Vgl由電荷不滅定律,可求得feedthroughΔV©ChiMeiOptoelectronicsPDD1/PD2Page20ΔV+Voltage-VoltageTransmittanceVdVsVcomOptimizedVcomforeachgrayVCOM液晶本身感受到的電壓是Vcom與Gamma電壓之間的壓差。但實際上，每一灰階是由Vcom與兩正負周期的GammaVoltage組成。所以當正負周期的壓差不一樣時，就會產生Flicker的現象©ChiMeiOptoelectronicsPDD1/PD2Page21VCOM©ChiMeiOptoelectronicsPDD1/PD2Page22LCD驅動方式基礎—小結亮度控制液晶電場強弱控制CFpanel/TFTpanel間電壓差控制利用TFT作為開關液晶需要AC電壓驅動以Linebyline方式顯示Feedthrough造成optimizedVCOM偏移©ChiMeiOptoelectronicsPDD1/PD2Page23驅動系統架構及組成©ChiMeiOptoelectronicsPDD1/PD2Page24TimingControllerDataDriverTFT-LCDPanelScanDriverRGBpixelSTHSTVDC/DCConverterGammaCorrectionVccTTLRSDSMiniLVDSTTLLVDSTMDS(DVI)驅動電路三大區塊PCBACKT包含三大block:1.TimingController(TCON)2.GammaCorrection3.DC/DCConverter©ChiMeiOptoelectronicsPDD1/PD2Page25GAMMATCONDC/DCInputSignal(LVDS)驅動電路三大區塊©ChiMeiOptoelectronicsPDD1/PD2Page26驅動系統架構-1TFT-LCDPanelTCONRGBdataSTHSTVDC/DCGammaFPCDataDriverScanDriver1PATH架構:©ChiMeiOptoelectronicsPDD1/PD2Page272PATH架構:TFT-LCDPanelTCONDataDriverRGBdataFSTHDC/DCGammaBSTHScanDriverSTV驅動系統架構-2目的:lowerclockrateforEMI©ChiMeiOptoelectronicsPDD1/PD2Page28TimingController（LVDSInput）DC/DCConverter&ReferenceVoltageTFTLCDPanel（1280*3*1024）LampConnector（JST）InputConnector（JAE）ScanDriverICDataDriverICBacklightUnitLVDSData（8-bit）LVDSclockVccGNDSELLVDSVLDataEDIDCLKEDIDVEDIDEDIDEEPROM©ChiMeiOptoelectronicsPDD1/PD2Page29InputDataConversionOutputDataFormattingDataDriverControlScanDriverControlSyncLCPolarityControldeRGBDatainclkckvstvoegvongvoffRGBdataout(a)RGBdataout(b)dinva_ckh/b_ckha_sth/b_stha_tp1/b_tp1polLineBufferMemorymanagementTCON架構©ChiMeiOptoelectronicsPDD1/PD2Page30Input/OutputTimingCPVSTVVGHCPVOEOut©ChiMeiOptoelectronicsPDD1/PD2Page31G-IC工作原理–單一顆IC內部架構主要用來控制水平線的開關控制機制為一次一條線的開,其他線都是關的主要由移位暫存器來完成主要架構水平和水平線之間不可以overlapOutputbufferLevelshifterBi-directionalshifterregisterLevelshifterOut123…………..254255256CPVOEMODEXAOSTV2STV1L/R…….…….…….VCOMVDDVSSVLVEEOutputbufferLevelshifterBi-directionalshifterregisterLevelshifterOut123…………..254255256CPVOEMODEXAOSTV2STV1L/R…….…….…….VCOMVDDVSSVLVEE1.STV:一個畫面開始通知2.CKV:通知每個暫存器單元動作,當有上緣觸發3.L/R:決定移位方向(TV機種可以作反轉機制,但OA機種已經固定方向)4.OE:清掉overlap處5.Mode:選用channel數©ChiMeiOptoelectronicsPDD1/PD2Page32ScanDriverTiming©ChiMeiOptoelectronicsPDD1/PD2Page33DataDriver架構Sample&hold©ChiMeiOptoelectronicsPDD1/PD2Page34DQCKDQCKDQCKDQCKDQCKDQCKDQCKDQCKCLKState1State2State3State4State5State6State7State8STHILinebufferNo1pixelRGBNo2pixelRGBNo3pixelRGBNo4pixelRGBNo5pixelRGBNo6pixelRGBNo7pixelRGBNo8pixelRGBRGBRSDSdataOnehorizontallinedataobtaininLinebufferLevelshiftTP1POLDAC&OutbufferOutputMultiplexerTP1Data1Data2Data3CLKSTHISTHOSTHISTHOSTHISTHOPanel©ChiMeiOptoelectronicsPDD1/PD2Page35DC/DCConverterDC-DCConverterinputpowerSourceDriveranalogGateOnvoltageGateOffvoltage©ChiMeiOptoelectronicsPDD1/PD2Page36PowerDC架构电源PatternGPWMICVaaV5V5VVglVghPanelGammaVcc3.3VChargePumpT-CONVCOM©ChiMeiOptoelectronicsPDD1/PD2Page37Power種類•首先,先了解整個panel需要哪些電壓VinNB:3.3VMonitor:5VTV:5Vor12VVAABoostcircuitVGHPChargebumpVGLChargebump(TV機種)(OA機種只有2.5V,給TCONI/O,SDRAM,EEPROM,D-IC,TCONcore,G-IC)TurnoffTFTTurnonTFTVref(431circuit)OPcircuitD-ICanalogpowerGammavoltage&Vcomvoltage(電阻分壓產生)3-StepVGH©ChiMeiOptoelectronicsPDD1/PD2Page38T-CONRegularIC©ChiMeiOptoelectronicsPDD1/PD2Page39VCCV5V1©ChiMeiOptoelectronicsPDD1/PD2Page40PowerDCV