LCD_驱动原理

null液晶顯示器驅動系統 講師 :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種類液晶分子的排列液晶分子的排列CrystallineLiquid CrystallineLiquid K SmC SmA N LBiaxialUnaxialIsotropicTemperature液晶的分類液晶的分類液晶的電光特性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 ( ) 液晶的光學特性液晶的光學特性Optical PositiveOptical NegativeHelical Axis Optical AxisOptical Axis液晶驅動原理液晶驅動原理電極電極液晶Field OFFField ON液晶顯示器主要優缺點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) 1980 PDLC (Polymer Dispersive LC) 1988 PSCT (Polymer Stabilized Cholesteric Texture) 1993 Other DS (Dynamic Scattering) 1968 PC (Phase Change) 1968 GH (Guest Host) 1968 ECB (Elcetrical Control Birefregency) 1971 BTN (Bistable Twist Nematic) 1995 IPS (In Plane Switch) 1995 VA (Vertical Alignment)1996TN 型 LCDs 顯示原理TN 型 LCDs 顯示原理液晶分子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STN LCDs 顯示原理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 CurveTN & STN 電光轉移曲線 V-T Curve100%90%10%Vns STN Vs STNVs TNVns TNTVTN 與 STN 的電壓漂移TN 與 STN 的電壓漂移T100%VSTN ModeLCDs 驅動方式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LCDs 靜態驅動法VsigVcVsVc-VsONOFF多工驅動法 (振幅選擇驅動法, APT)多工驅動法 (振幅選擇驅動法, APT)多工驅動法的限制多工驅動法的限制APT 驅動波形APT 驅動波形IAPT 驅動波形IAPT 驅動波形APT AddressingIAPT AddressingAPT 與 IAPT 方式比較APT 與 IAPT 方式比較APT Addressing Low Voltage Segment Driver : 2D High Voltage Common Driver : 2F IAPT Addressing Offset +D for Positive Polarity Offset +F for Negative Polarity Voltage Range of Segment Driver : F+D Voltage Range of Common Driver : F+D 高容量多工驅動的對策高容量多工驅動的對策STN LCDs 規格STN LCDs 規格Operation Voltage Vop :Bias Ratio : Steepness : Selection Ratio : STN LCDs 驅動電壓計算STN LCDs 驅動電壓計算If Voff=2V, N=240 rows, Then : APT : Segment Driver : 2.96V, Common Driver : 44.40V IAPT : Segment & Common Drivers : 23.68VSTN LCDs Drivers 架構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)LPF+D 0F-D 2D偏壓位準........................................................DF(HLHL...H)............................HLHH並列輸出垂直訊號電極2D02D2DIAPT 參考電壓IAPT 驅動 IC灰階顯示 ─ FRC灰階顯示 ─ FRCFrame Rate Control, FRC : 灰階顯示 ─ PWM灰階顯示 ─ PWMPulse Width Modulation, PWM :灰階顯示 ─ PHM灰階顯示 ─ PHMPulse High Modulation, PHM : 液晶的頻率響應液晶的頻率響應Vertical Crosstalk of STN LCDsVertical Crosstalk of STN LCDsVertical Crosstalk 的抑制 (一)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)Vertical Crosstalk 的抑制 (二)採用補償驅動週期Vertical Crosstalk 的抑制 (三)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 LCDsHorizontal Crosstalk of STN LCDsABABHorizontal Crosstalk 的抑制Horizontal Crosstalk 的抑制ABFrame Response of STN LCDsFrame Response of STN LCDsActive Addressing for STN LCDsActive Addressing for STN LCDsActive Addressing 驅動電壓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 = 21.909V Output Range of Segment Driver is about 44V. Common Driver of Common Driver is about 3V.Segment Voltage of Active AddressingSegment Voltage of Active AddressingActive Addressing 的矩陣運算Active 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（Time）列（Column）Column Voltage Matrix矩陣運算方式矩陣運算方式行（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 SequentialColumn Sequential 硬體架構Column Sequential 硬體架構Time Sequential 硬體架構Time Sequential 硬體架構主動矩陣式液晶顯示器 AM-LCDs主動矩陣式液晶顯示器 AM-LCDsTFT LCDs 等效電路TFT LCDs 等效電路Row DriversColumn DriverArrangement of Color Filter Arrangement of Color Filter Stripe Triangle Pixel Structure of TFT LCDsPixel Structure of TFT LCDsCs on Common 與 Cs on Gate 架構Cs on Common 與 Cs on Gate 架構Timing Chart of TFT LCDsTiming Chart of TFT LCDsFrame TimeGate 1 2 3 NTimeTFT LCDs Driving MethodTFT LCDs Driving MethodColumn InversionDot InversionRow InversionFrame InversionDirect Driving of TFT LCDsDirect Driving of TFT LCDs DC Bias of CommonGrayScale Voltage AC Modulation Addressing of TFT LCDsAC Modulation Addressing of TFT LCDsCommon WaveformGraylevel Voltage1Frame / 1 LineTFT LCDs 的電光效應 Direct AddressingTFT LCDs 的電光效應 Direct AddressingTFT LCDs 的電光效應 AC AddressingTFT LCDs 的電光效應 AC AddressingTFT LCDs Driving Waveform Cs on Common (一)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 Common (二)TFT LCDs Driving Waveform Cs on Gate TFT LCDs Driving Waveform Cs on Gate TFT 電容效應的影響TFT 電容效應的影響液晶電容的效應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VgTFT 補償驅動法TFT 補償驅動法3 Level Addressing4 Level Addressing3 Level Addressing3 Level Addressing4 Level Addressing4 Level AddressingVst=VctB(+)B(-)B(-)B(+)W(+)W(+)W(-)W(-)B(+)W(-)B(-)W(+)ΔVp(+)ΔVp(-)ΔVp=CgdVghl/CtCsVge(-)/CtCsVge(+)/Ct正極性負極性正極性負極性Ct=Cs+Clc+CgdCs on Gate 電壓補償方式Cs on Gate 電壓補償方式Comparsion of Addressing MethodComparsion of Addressing MethodHorizontal Line CrosstalkHorizontal Line CrosstalkABCscCscCscTFT SubstrateColor Filter SubstrateHorizontal Area CrosstalkHorizontal Area CrosstalkABVertical Area CrosstalkVertical Area CrosstalkShading CrosstalkShading CrosstalkShading Crosstalk 的抑制Shading Crosstalk 的抑制Gate Pulse 的傳遞延遲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)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 Appeared VA > VL : Disclination Disappeared VP > LC Threshold VoltageReverse Tilt 液晶畫素邊際電場效應(二)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驅動 IC － Scan DriverBidirectional Shift RegisterLevel Shift CircuitOutput BufferG1 G2 G3 ………...STVRSTVLCPVR/LVDDDVSSDVDDAVSSASTVRSTVLG1G2GxSerial In － Serial Out Analog Data DriverSerial In － Serial Out Analog Data DriverMultiplexerPro:Very simple. Fewer external connections. Con:Many analog inputs. Reduced pixel charging time. System Note : Sample clock : (Dot clock) / N, N Phases. Video Phase : NVariation on Multiplexer Pro: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 HoldSerial In － Parallel Out Analog Data Driver (一)Serial In － Parallel Out Analog Data Driver (一)Serial In － Parallel Out Analog Data Driver (二)Serial In － Parallel Out Analog Data Driver (二)Double Sample and Hold / Multi-PhasePor : Reduced operation frequency . System Note : Video In : N Video Phase : N Shift Clock : (Dot Clock) / N.Digital Data Driver (一)Digital Data Driver (一)Digital-to-analog ConvertersPor : Digital input. Con : Complex. Requires sufficient precision to correct for LC response variation.Ramp InSampled RampPor : Digital input. Programmable ramp. Con : Complex circuit. High speed digital circuits. Reduced pixel charging time.Digital Data Driver (二)Digital Data Driver (二)1-of-n SelectorSimple DAC Pro : Digital input. Programmable external voltages. Con : Complex circuit. High speed digital circuits. Many pass gates per data line.Digital Data Driver (三)Digital Data Driver (三)All Digital Circuit Gamma Correction of LCDGamma Correction of LCDAnalog Correction : 2 ~ 3 Segment Approach. Digital Correction : External fixed voltage. Gamma Correction Simple CaseGamma Correction Simple CaseTransmissionVoltageThe Block Diagram of the TFT LCD ModuleThe Block Diagram of the TFT LCD ModuleThe TFT LCD Module TypeThe TFT LCD Module TypeClassified into two kinds by data driver Analog type TFT-LCD module The analog data drivers The analog interface to PC Only NEC Digital type TFT-LCD module The digital data drivers The ADC/ LVDS/PanelLink interface to PC MainstreamThe Analog InterfaceThe Analog InterfaceThe ADC InterfaceThe ADC InterfaceThe LVDS/PanelLink InterfaceThe LVDS/PanelLink InterfaceAnalog/ADC/LVDS/PanelLinkAnalog/ADC/LVDS/PanelLinkAnalog Interface True Color Sampling Error Low Edge Sharpness Noise in the Analog Signal Transmission Analog/ADC/LVDS/PanelLinkAnalog/ADC/LVDS/PanelLinkADC Interface Mainstream in the Desktop LCD Monitor Interface Sampling Error Low Edge Sharpness Noise in the Analog Signal Transmission EMI Issue for High Resolution Format Low Image Quality and High CostAnalog/ADC/LVDS/PanelLinkAnalog/ADC/LVDS/PanelLinkLVDS Interface Mainstream in the Notebook PC Interface High Edge Sharpness Reducing EMI & Number of Cable Line High Image Quality and Low Cost Short Transmission Length & Low Noise Margin Compatible Issue Analog/ADC/LVDS/PanelLinkAnalog/ADC/LVDS/PanelLinkPanelLink Interface Application in the Desktop LCD Monitor Interface High Edge Sharpness Reducing EMI & Number of Cable Line High Image Quality and Low Cost Second Supply Source IssueTFT Module 設計考慮(一)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)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 的開口率影響因素大面積高解析度 TFT LCDs 的開口率影響因素Plasma Addressing LCDsPlasma Addressing LCDsIn-Plane-Switch Mode LCDsIn-Plane-Switch Mode LCDsVertical Alignment Mode LCDsVertical 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 ModesComparison of Liquid Crystal ModesSlightly 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TNIPSVA