STN TFT_LCD knowledge training

1、 STN、TFT_LCD工作原理讲解LCD技术支援部 沈文全2005/11/03Technology for Easy Living !Page23、TFTLCD认识2、STN-LCD工作原理1、SUNPLUS Driver认识STN工作原理STN产品的驱动波形STN常见应用问题CSTN知识灰度显示原理Technology for Easy Living !Page3SUNPLUS Driver IC： SPLC780A/B/C/D SPLC100A SPLC063A SPLC783ACharacterFAXCordless PhoneGraphicMobile PhonePDA/DC SPL

2、C560C SPLC562C SPLC563A SPLC564A SPLD803B SPLD804ACOBCOGCOBCOGCOGPDA/dic. SPLC782A SPLC093C/D SPLC095A SPLC701B SPLC501C SPLC502A SPLC506B SPLC550A SPLC086A SPLD1080A SPLD1120ATechnology for Easy Living !Page4LCDLCD的基本结构：的基本结构：液晶盒中间会均匀撒布间隙物质spacer, 支撑两片玻璃，使之间间隙均匀。Glass Substrate Liquid Crystal Glass

3、 Substrate Polarizer/Diffusive Reflector Polarizer spacerspacerTechnology for Easy Living !Page5 偏光片的功能：偏光片的功能：Technology for Easy Living !Page6定向层的作用：定向层的作用：可使液晶分子呈现规则的排列 达到扭转的功能；不同型态之LCD有不同的扭转角。 Technology for Easy Living !Page7LCDLCD的工作原理：的工作原理： 液晶与偏光片的效应组合 未加电压未加电压 : : 当光线通过上层偏光片, 以一特定的方向进入LCD后,

4、 藉由液 晶的扭转将光路径旋转至特定之角度, 而得以穿透下层偏光片的轴向。 施加电压施加电压 : : 原有液晶分子排列的状态经过施加电压后, 已失去了旋转光 路径的功能,因此光线无法透过直交的偏光片。Technology for Easy Living !Page8100%90%10%TNTNTechnology for Easy Living !Page9STNSTN驱动波形（驱动波形（分为三大类）分为三大类）：1.1.B BTYPETYPE（还有还有A A、C CTYPETYPE两种两种）2.Hi2.HiFAS FAS (high frequency amplitude selection

5、)(high frequency amplitude selection)3.MLA 3.MLA （multi-line addressing)multi-line addressing)Technology for Easy Living !Page10 BIAS的波形算法： A type、 B type波形1/a从COM算出： (Vlcd V1)/(Vlcd V5)=1/aA typeB typeTechnology for Easy Living !Page11B BTYPETYPE：comcomsegseg1 framev0v0v1v1v2v2v3v3v4v4v5v5Technolog

6、y for Easy Living !Page12HiHiFAS FAS (high frequency amplitude selection)(high frequency amplitude selection)1 frameVHVHVLVLV0V0V1V1VMVMTechnology for Easy Living !Page13MLA MLA （multi-line addressing)multi-line addressing)Technology for Easy Living !Page14液晶盒等效电路负载SegcomLCTechnology for Easy Living

7、 !Page15LCD Bias Circuit StructureVLCDV1V2V3V4OPOPOPOPRRRRNRV0OPBias AdjustV1V2V3V4V5VLCDThe Optimum LCD Bias Voltage equation :(V12 - V22 ) + (V52 - V42) = 0VSSTechnology for Easy Living !Page16升压电容ITO阻值S1S2S1S2所以：当回路中阻抗过大时，RC效应明显，升压的效能下降。 VOUTV0=VLCDTechnology for Easy Living !Page17GNDV DDVSSVDDS

8、PLC093CSPLC093CITO LAYOUT NG ExampleITO LAYOUT NG Example（SPLC093CSPLC093C） : :Technology for Easy Living !Page18 设VDD=3V，RVDD=RVSS=500ohm；产品全黑画面耗电流为100uA，在 雪花画面为150uA,等效图为：ICVDDVSSRRVDD2此时实际加在IC上的电压： VDD2=(VDD-VSS)- IDD*2R=3-0.1= 2.9V当显示耗电流大的雪花画面时： VDD2 = 2.85V (前章节有介绍雪花画面耗电流大的问题)故当Vout=3*VDD=9.0V(

9、3倍压)时，以雪花画面来测Vout=3* VDD2 =7.55V (若VLCD电压为8.0V，故此时会显示淡)ITO LAYOUT NG ExampleITO LAYOUT NG Example（SPLC093CSPLC093C）说明说明 : :Technology for Easy Living !Page19CSTNCSTN相关知识：相关知识：Glass Substrate (0.40.7 mm)Liquid Crystal (6 mm)Glass Substrate (0.4 0.7mm)ITO 电极PI 配向膜Polarizer/Diffusive Reflector (0.3 mm)

10、ColorFilterPolarizer (0.3 mm)内部结构: FSTN + Color Filter: FSTN + Color FilterTechnology for Easy Living !Page20Technology for Easy Living !Page21Technology for Easy Living !Page22CSTN就是: 灰度显示 +color-filter灰度显示有两种方式：FRCFRC: Frame Rate Control（具有FRC调制灰度的 controller+一般的mono pure driver)PWMPWM: Pulse Widt

11、h Modulation(一般的controller具有PWM调制灰度的pure driver.FRC & PWM can be combinedFRC & PWM can be combined. Technology for Easy Living !Page23 1stFrame 2ndFrame 3rdFrame 4thFramePixel 1Pixel 2Pixel 3Pixel 4Pixel 55/5 ON4/5 gray3/5 gray2/5 gray1/5 OFFResultTimeTechnology for Easy Living !Page241/32/3

12、3/3Vnon_sVselect我们看到的效果Technology for Easy Living !Page25RMS voltageRMS voltageTransmissionVoffbackgrounddark stateVonV1V2gray 1gray 2灰度与V_T的关系：Technology for Easy Living !Page26Technology for Easy Living !Page27TFT-LCD认识：TFT-TFT-薄膜薄膜电晶体电晶体( (Thin Film Thin Film Transistor)Transistor)非晶硅非晶硅a-a-SiSi:

13、 :目前产品的主流，但目前产品的主流，但迁移率低；多晶硅多晶硅p-p-SiSi ：由于a-Si TFT的主要缺点是迁移率低，原因是薄膜中硅粒很小，并且晶粒结构是随时机的，如果使a-Si薄膜 中的硅粒在高温下再结晶，使用权晶粒长在到微米量级，允许电子更加自由地流动，称为多晶硅，迁移率增大100倍。高温多晶硅（高温多晶硅（HTPSHTPS）：制程温度达1000度。所以必须采用昂贵的石英玻璃，故未能获得广泛应用。低温多晶硅（低温多晶硅（LTPSLTPS）Low Temperature Ploy SiliconLow Temperature Ploy Silicon ：首先是在玻璃基板上形成一层a-S

14、i ，然后采用激光热处理，将a-Si 转变为多晶硅p-Si。由于太多的优点，将是未来的主流！ TFTTFTLCDLCD分类：分类：Technology for Easy Living !Page28Advantages of LTPS TFT-LCD 较高的电子迁移率 可靠度高 消耗功率小 高解析及高开口率 较简单的模组结构Technology for Easy Living !Page29GDSDSG (Cr或Mo)DSG（a-Si）或（p-Si）n+a-Si:HSiO2Technology for Easy Living !Page30TFT LCDResolutionSource : S

15、ID TutorialPixel ArrangementTechnology for Easy Living !Page31Arrangement of Color FilterChoose Different Color Filter ArrangementStripe Triangle/Delta Pentile RGBW For Text DisplayFor Graphic DisplayBrightness EnhancementTechnology for Easy Living !Page32Array面板說明comITOCLCGate DriverSource DriverTe

16、chnology for Easy Living !Page33Equivalent Circuit of TFT LCDCS on Common CS on GateEquivalent CircuitClcCsClcCsCommonCommon (N-1)thScan Line (N-1)thScan LineNth Scan LineNth Scan LineCs on Common Mode Cs on Gate ModeCgdCgd液晶電容儲存電容掃描電極資料電極共通電極Mth Data LineMth Data Line資料電極掃描電極:Clc:Cs:Common:Cgd寄生電容液

17、晶畫素電容:Clc+CsClcCsCommon1 (N-1)thScan LineNth Scan LineCs on Gate ModeCgdMth Data Line資料電極Common2Technology for Easy Living !Page34液晶畫素TFTGate LineData LineCsCs液晶畫素TFTCommonCommonGate LineData LineCsCs Cs on CommonCs on GateTechnology for Easy Living !Page35TFT LCDs驱动波形Cs on CommonSourceDrainGateVgpp

18、VsppVgon-minVgoff-minVshVdhVslVdlVgdVghVglVgdCommonVstVst:影像訊號的直流位準TgTFT LCD 驱动波形 (Cs on Common, Common = DC Bias)Technology for Easy Living !Page36TFT LCDs 驱动波形Cs on Gate SourceDrainGateVgppVsppVgon-minVgoff-minVshVdhVslVdlVgdVghVglVgdCommonVstVst:影像訊號的直流位準VdVdTgVc:Technology for Easy Living !Page3

19、71 2 3 4 512345Frame NColumnsLines+ + + + + + + + + + + + + + + + + + + + +1 2 3 4 512345Frame N+1 ColumnsLines 1 2 3 4 512345Frame NColumnsLines+ + + + + + + + + + + + +1 2 3 4 512345Frame N+1 ColumnsLines + + + + + + + + + 1 2 3 4 512345Frame NColumnsLines+ + +1 2 3 4 512345Frame N+1 ColumnsLines

20、+ + + + + + + + + + + + + + + + + + + 1 2 3 4 512345Frame NColumnsLines+ + +1 2 3 4 512345Frame N+1 ColumnsLines+ + + + + + + + + + + + + + + + + + + +Column InversionDot InversionRow InversionFrame InversionTechnology for Easy Living !Page38Direct Driving and AC Modulation AddressingDC VCOMLarge Si

21、ze Panel : 9v15v HV Source Driver DC Bias of CommonGrayScale Voltage V0V1V2V62V63V63V62V2V1V01 Frame / 1 LineV0V1V2V62V63V63V62V2V1V0Common WaveformGraylevel Voltage1Frame / 1 LineAC VCOMSmall Size Panel : 5v LV Source DriverTechnology for Easy Living !Page39Gate DriverGate Driver Architecture: Bidi

22、rectional Shift RegisterLevel Shift CircuitOutput BufferG1 G2 G3 .STVRSTVLCPVR/LVDDDVSSDVDDAVSSASTVRSTVLG1G2GxTechnology for Easy Living !Page40Source Driver & Gamma BufferDACSDDACSDDACSDDataDataDataDACSDDACSDDACSDDataDataDataDACDACDACDataDataDataChoosing Suitable Source Driver Architecture to s

23、ave powerNeed ultra low power source driver OP designNeed to optimize the OP driving periodGamma buffer stability issueTechnology for Easy Living !Page41Gamma & Gamma BufferUse Gamma Buffer to provide Different Gamma CurveV0V1V2VnV3GSN0GSN1GSN2GSN3GSN255GSN254Technology for Easy Living !Page42Charge PumpBasic Idea of PumpTechnology for Easy L