《LCD驱动系统》PPT课件.ppt

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,固體結晶,液晶,液體,加熱,加熱,冷卻,冷卻,液晶分子的種類,液晶分子的排列,Crystalline,Liquid Crystalline,Liquid,K SmC SmA N L,Biaxial,Unaxial,Isotropic,Temperature,液晶的分類,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,Optical Positive,Optical Negative,Helical Axis Optical Axis,Optical Axis,液晶驅動原理,電極,電極,液晶,Field OFF,Field ON,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,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)1996,TN 型 LCDs 顯示原理,液晶分子,Field OFF,Field 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,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 Curve,100%,90%,10%,Vns STN,Vs STN,Vs TN,Vns TN,T,V,TN 與 STN 的電壓漂移,T,100%,V,STN Mode,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,Vsig,Vc,Vs,Vc-Vs,ON,OFF,多工驅動法 (振幅選擇驅動法, APT),多工驅動法的限制,APT 驅動波形,IAPT 驅動波形,APT Addressing,IAPT Addressing,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,STN LCDs 規格,Operation Voltage Vop :,Bias Ratio :,Steepness :,Selection Ratio :,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 : 23.68V,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),LP,F+D,0,F-D,2D,偏,壓,位,準,DF,(HLHL.H),H,L,H,H,並列輸出,垂直訊號電極,2D,0,2D,2D,IAPT 參考電壓,IAPT 驅動 IC,灰階顯示 FRC,Frame Rate Control, FRC :,灰階顯示 PWM,Pulse Width Modulation, PWM :,灰階顯示 PHM,Pulse High Modulation, PHM :,液晶的頻率響應,Vertical Crosstalk of STN LCDs,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),採用補償驅動週期,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 LCDs,A,B,A,B,Horizontal Crosstalk 的抑制,A,B,Frame Response of STN LCDs,Active Addressing for STN LCDs,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 Addressing,Active Addressing 的矩陣運算,列向量（Column）,時間（Time）,行向量（Row）,Bit-Map Image Matrix,Row Function Matrix,時間（Time）,列（Column）,Column Voltage Matrix,矩陣運算方式,行（Row）,行向量（Row）,列向量（Column）,Bit-Map Image Matrix,Row 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 Sequential,Column Sequential 硬體架構,Time Sequential 硬體架構,主動矩陣式液晶顯示器 AM-LCDs,TFT LCDs 等效電路,Row Drivers,Column Driver,Arrangement of Color Filter,Stripe,Triangle,Pixel Structure of TFT LCDs,Cs on Common 與 Cs on Gate 架構,Timing Chart of TFT LCDs,Frame Time,Gate 1 2 3 N,Time,TFT LCDs Driving Method,Column Inversion,Dot Inversion,Row Inversion,Frame Inversion,Direct Driving of TFT LCDs,DC Bias of Common,GrayScale Voltage,AC Modulation Addressing of TFT LCDs,Common Waveform,Graylevel Voltage,1Frame / 1 Line,TFT LCDs 的電光效應 Direct Addressing,TFT LCDs 的電光效應 AC Addressing,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 Gate,TFT 電容效應的影響,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,Cs,Clc,Cgd,Csd,Cgs,Vct,Ch(N-1),Ch(N),Vs,垂直影像訊號,水平掃描訊號,Vg,水平掃描訊號,Vg,TFT 補償驅動法,3 Level Addressing,4 Level Addressing,3 Level Addressing,4 Level Addressing,Vst=Vct,B(+),B(-),B(-),B(+),W(+),W(+),W(-),W(-),B(+),W(-),B(-),W(+),Vp(+),Vp(-),Vp=CgdVghl/Ct,CsVge(-)/Ct,CsVge(+)/Ct,正極性,負極性,正極性,負極性,Ct=Cs+Clc+Cgd,Cs on Gate 電壓補償方式,Comparsion of Addressing Method,Horizontal Line Crosstalk,A,B,Csc,Csc,Csc,TFT Substrate,Color Filter Substrate,Horizontal Area Crosstalk,A,B,Vertical Area Crosstalk,Shading Crosstalk,Shading Crosstalk 的抑制,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),Reverse Tilt,畫素電極,鄰近電極,共通電極,VP,VL,VA,VA VL : Disclination Disappeared VP LC Threshold Voltage,Reverse Tilt,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,Bidirectional Shift Register,Level Shift Circuit,Output Buffer,G1 G2 G3 .,STVR,STVL,CPV,R/L,VDDD,VSSD,VDDA,VSSA,STVR,STVL,G1,G2,Gx,Serial In Serial Out Analog Data Driver,Multiplexer,Pro:Very simple. Fewer external connections. Con:Many analog inputs. Reduced pixel charging time. System Note : Sample clock : (Dot clock) / N, N Phases. Video Phase : N,Variation 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 Hold,Serial In Parallel Out Analog Data Driver (一),Serial In Parallel Out Analog Data Driver (二),Double Sample and Hold / Multi-Phase,Por : Reduced operation frequency . System Note : Video In : N Video Phase : N Shift Clock : (Dot Clock) / N.,Digital Data Driver (一),Digital-to-analog Converters,Por : Digital input. Con : Complex. Requires sufficient precision to correct for LC response variation.,Ramp In,Sampled Ramp,Por : Digital input. Programmable ramp. Con : Complex circuit. High speed digital circuits. Reduced pixel charging time.,Digital Data Driver (二),1-of-n Selector,Simple DAC Pro : Digital input. Programmable external voltages. Con : Complex circuit. High speed digital circuits. Many pass gates per data line.,Digital Data Driver (三),All Digital Circuit,Gamma Correction of LCD,Analog Correction : 2 3 Segment Approach. Digital Correction : External fixed voltage.,Gamma Correction Simple Case,Transmission,Voltage,The Block Diagram of the TFT LCD Module,The TFT LCD Module Type,Classified 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 Mainstream,The Analog Interface,The ADC Interface,The LVDS/PanelLink Interface,Analog/ADC/LVDS/PanelLink,Analog Interface True Color Sampling Error Low Edge Sharpness Noise in the Analog Signal Transmission,Analog/ADC/LVDS/PanelLink,ADC 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 Cost,Analog/ADC/LVDS/PanelLink,LVDS Interface Mainstream in the Notebook PC Interface High Edge Sharpness Reducing EMI & Number o