液晶显示器驱动原理forFATeamppt课件教案.ppt

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1、液晶显示器驱动原理液晶显示器驱动原理For:NBLCM F.A.TeamAuthor:Jessica _ LinDate:2009/1/8液晶显示操作原理液晶显示操作原理TFT-LCDTFT-LCD驱动原理驱动原理Storage Capacitor(Cst)Feed-through与与Vcom补偿补偿液晶极性反转驱动与液晶极性反转驱动与FlickerGamma调整调整常见的问题常见的问题 Q&AOutline液晶显示操作原理液晶显示操作原理图像组成图像组成RedGreenBlueWhiteGray Scale 0816243240485663对6 bit显示器而言,共可以显示26x 26x 2

2、6=262,144对8 bit显示器而言,共可以显示28x 28x 28=16,777,216LCD可显示的颜色数目可显示的颜色数目TFTPolarizer偏光板 CFPolarizer偏光板 PCB灯管LC cellTFT-LCD结构示意图结构示意图光源垂直偏光板玻璃电极玻璃电极液晶水平偏光板LCD如何控制亮度如何控制亮度EGDSTFT-LCD制造流程制造流程TFT-LCD驱动原理驱动原理Response TimeStorage Capacitor(Cst)Feed-through与与Vcom补偿补偿 Flicker与液晶极性反转驱动与液晶极性反转驱动Gamma调整调整Scan Line扫描

3、线Data Line讯号线Response TimeVonVoffDrivingsignalLCD opticresponseResponse time of MVA test cellTrTfGDSData lineScan lineVstVcomClcCstCgsVgVdVsTFT LCD Cell让液晶显示器正确显示让液晶显示器正确显示如何充电到正确的电压准位如何充电到正确的电压准位?如何保持正确的电压准位如何保持正确的电压准位?液晶极性反转驱动液晶极性反转驱动液晶必须以交流信号驱动液晶必须以交流信号驱动否则液晶将受破坏否则液晶将受破坏odd frameevenframe16.67mst

4、imeVcomVcomVgVdVsVVghVglFeed-through:V=(Vgh-Vgl)*Cgs/(Cgs+Cst+Clc)1 line1 frameFeed-throughGDSData lineScan lineVst VcomClcCstCgsVgVdVsScan line signaldata line signalLC所见电压CF电极电压Transmittance+V-VIdeal VcomV+V-VTransmittanceVdVsVcomOptimized VcomTransmittanceData VoltageData Voltage调整调整Vcom可补偿可补偿V各灰

5、阶各灰阶Clc不一样大不一样大,各阶最佳各阶最佳Vcom值也会不一样值也会不一样适当调整各灰阶正负极性电压适当调整各灰阶正负极性电压,使各阶最佳使各阶最佳Vcom值尽量接近值尽量接近Flickertime16.67msVcom正负极性电压不均衡正负极性电压不均衡正负极性亮度不均衡正负极性亮度不均衡Flicker调整调整调整调整VcomVcom有效果有效果有效果有效果但整片但整片但整片但整片panelpanel的的的的VcomVcom并非完全一样并非完全一样并非完全一样并非完全一样!Applied voltage shifts液晶极性反转驱动液晶极性反转驱动+Frame inversion-Lo

6、wer power-Sensitive to flicker due to lack of spatial averaging-Sensitive to horizontal and vertical cross-talk+-+-Row inversion-+-+-Higher power-Reduced flicker-Lower vertical cross-talk-Sensitive to horizontal cross talk液晶极性反转驱动液晶极性反转驱动液晶极性反转驱动液晶极性反转驱动+-+-+-+-+-+-+-+-Column inversion-+-+-+-+-+-+-+

7、-+-Lower power-Reduced flicker-Lower horizontal cross-talk+-+-+-+-+-+-+Dot inversion-+-+-+-+-+-+-Higher power-Minimum flicker-Highest image quality液晶极性反转驱动液晶极性反转驱动液晶极性反转驱动液晶极性反转驱动+-+-+-+-+-+-+-+2 line inversion-+-+-+-+-+-+-+-Higher power-Minimum flicker-High image qualityWhat Is Gamma CurveRedGreenB

8、lueWhiteGray Scale 0816243240485663The gamma curve is the curve that presents the luminance ofeach gray scale.LGray scaleTimingControllerData DriverTFT-LCD PanelScan DriverRGB pixelSTHSTVDC/DCConverterGammaCorrectionVccTTLRSDSTTLLVDSTMDSTFT-LCD驱动电路简介驱动电路简介GAMMATCONDC/DCInput Signal(LVDS)TAB ICTFT-LC

9、D驱动电路驱动电路TFT LCD PanelTHE EDNTHANKS FOR YOUR ATTENDANCE5.常见的问题常见的问题 1.Flicker2.Cross Talk3.Image Sticking4.3-level VGH的作用的作用1.Flicker产生的原因+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Frame 1Frame 1Frame 2Frame 2如何破解FlickerPattern(2 line inversion)+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

10、-+-+-+-+-+-+-+-+Frame 1Frame 1Frame 2Frame 22.CrossTalk产生的原因2.1 Vaa 电压不稳2.2 ScanPulse overlapeScan NScan N+1Scan NScan N+1Scan NScan N+1Scan NScan N+1可由OE 控制3.Image StickingAns:加速VGL放电至GND因若Scan Pulse的准位维持在VGL,其漏电流很小4.3-level Scan Pulse的功用VGHVGLVfh=V xCgdCgd+Clc|CstVAns:同一个画面各dot的Vfh愈小愈容易找到一组Vcom去满足画面中各dot,其Flickler现象愈小5.Debug Process1.Get a good test fixture:6/8 bit pattern generator2.Know the I/F(TTL,LVDS,TMDS)3.Know the connector pin define4.Light on5.Fail analysis6.Find the wrong sourcea.Power Check(Vaa,Vcom,Vgh,Vgl,Vcc)b.Signal Check(The abnormal display)7.Timing Analysis