LCD 基本驱动原理.ppt

按一下以編輯母片標題樣式,按一下以編輯母片,第二層,第三層,第四層,第五層,*,LCD,基本,驅動原理,PD/ACD Seaboy,課程大綱,顯示的基本原理,1.,偏光片的使用,2.Rubbing,的定向,3.,液晶的定向,4.,加入電場後的液晶,5.,液晶與偏光片的效應組合,LCD,基,本驅動原理,1.,液晶與外加電場的關係,2.TFT,的基本驅動,（,a,）,TFT,的機構,（,b,）,TFT,的簡易等效電路,（,c,）面板的各種極性與,Common,的不同驅動,（,d,）,Cst on Common&Cst on Gate,LCD,的顯示原理,基本上，,LCD,是藉由電場加於液晶，改變其雙折射現像，並配合偏光片來決定光的路徑。,以顯示出對比，並利用,color filter,來呈現出色彩。,(1).,偏光片的使用：,使用偏光片，可決定光的行進路線。,(2).,Rubbing,的定向：,可使液晶分子呈現規則的排列,(3).,液晶的定向,：可使液晶分子呈現規則的排列後，達到扭轉的功,能；不同型態之,LCD,有不同的扭轉角。,(4).,加入電場後的液晶：,當所加的電場強度高於液晶的臨限電壓時，,改變原有的扭轉排列狀態。,(5).,液晶與偏光片的效應組合：,未加電壓,：當光線通過上層偏光片，以一特定的方向進入,LCD,後，藉,由液晶的扭轉將光路徑旋轉至特定之角度，而得以穿透下,層偏光片的透過軸向。,施加電壓,：原有液晶分子排列的狀態經過施加電壓後，已失去了旋轉,光路徑的功能，因此光線無法透過直交的偏光片。,TFT,基本驅動,Clc,TFT Substrate,Color Filter Substrate,R,G,B,Clc,Clc,R,B,G,TFT,基本的剖面圖,舉例：,TFT LCD,等效電路,Gate Drivers,Source Driver,1,H,1H,Clc,Cs,Cs,Cs,Cs,Cs,Cs,Cs,Cs,Cs,Clc,Clc,Clc,Clc,Clc,Clc,Clc,Clc,Glass,Glass,Gate Metal Deposition,Gate Patterning,SiNx,Deposition,i a-,Si,Deposition,n+a-,Si,Deposition,Active Patterning,Data Metal Deposition,Data Metal Patterning,n+a-,Si,Etch,SiNx,Deposition,Via Hole Patterning,ITO Deposition,Pixel Patterning,Pixel,Data,Passivation,SiNx,n+a-,Si,i a-,Si,Gate,insulator,SiNx,Gate,Via hole,Frame Time,Gate,1,2,3,N,1H,L1,L2,L3,DATA,TFT Timing chart,t,F,=16.7ms,t,g,(gate on time),G0,G1,G2,G3,+,V1,+V2,V3,off,off,off,on,on,on,off,off,off,off,off,off,Cst,Scanning at-a-line,-,Vgh,is applied to a gate line,-All,TFTs,on a gate line are turned on,-Current flows from data line to pixel and pixels on,the gate line are charged up to data voltage,-,Vgl,is applied to a gate line,-All,TFTs,on a gate line are turned off and pixels on,the gate line holds the charged voltage,TFT driving principle,Display Format,Resolution,VGA,SVGA,XGA,SXGA,UXGA,QXGA,Gate-on-time,480 x640 xRGB,600 x800 xRGB,768x1024xRGB,1024x1280 xRGB,1200 x1600 xRGB,1536x2048xRGB,34,s,27,s,21.7,s,16,s,13,s,10,s,Pixel Size(in 15.1”),480,m X 160m,384,m X 128m,300,m X 100m,234,m X 78m,192,m X 64m,150,m X 50m,Refreshing time,t,F,(Frame time)(dominated by the Pixel design,t,g,),Refreshing rate=1/,t,F,Gate switching time,t,g,(Gate-on time),t,g,(Gate-on time),=,t,F,(Frame time)/,total Gate line(dominated by product resolution),For example:,t,g,(Gate-on time)=16.7 ms/,768,(for 14.1”XGA)=,21.7,s,TFT resolution,R/G/B:,若,各以,6,bits,訊號控制,則可各得,2,6,=64,scales,1 dot:R/G/B,所組成所以螢幕上一個點由,6,X3=18 bits,所控制,故每個點顏色階數可有,2,18,=256,K scales,Full color(True color)scale:24 bits=17M scales,1M=1024K,1K=1024bits,Color scale Depends on,The charging capability,T-V(Transmission versus Voltage)curve,TN liquid crystal:Normally White,TFT mobility(,ie,carrier mobility,載子移動率,),Transmission(%),Voltage,像素,Pixel dimension:88X264 mm,2,點距,Dot dimension:264X264 mm,2,TFT resolution,Dot,Inversion,Gate,Inversion,Data,Inversion,Common,Inversion,面板的各種極性變化方式：,Column inversion,Line inversion,Dot inversion,Frame inversion,1st field,2nd field,Positive voltage,Negative voltage,Checkerboard Pattern,2,4,6,8,10,12,14,16,Gate_Even,Gate_Odd,Data_Even,Data_Odd,Spare,Vgh,=+15V,Vgl,=-15V,tg,=100s,Vdh,=+5V,Vref,=0V,Vdl,=-5V,Vgh,Vgl,Vdh,Vdl,Vref,Dot Inversion Pattern,2,4,6,8,10,12,14,16,Gate_Even,Gate_Odd,Data_Even,Data_Odd,Spare,Vgh,=+15V,Vgl,=-15V,tg,=100s,Vdh,=+5V,Vref,=0V,Vdl,=-5V,Vgh,Vgl,Vdh,Vdl,Vref,Gate Inversion Pattern,2,4,6,8,10,12,14,16,Gate_Even,Gate_Odd,Data_Even,Data_Odd,Spare,Vgh,=+15V,Vgl,=-15V,tg,=100s,Vdh,=+5V,Vref,=0V,Vdl,=-5V,Vgh,Vgl,Vdh,Vdl,Vref,Data Inversion Pattern,2,4,6,8,10,12,14,16,Gate_Even,Gate_Odd,Data_Even,Data_Odd,Spare,Vgh,=+15V,Vgl,=-15V,tg,=100s,Vdh,=+5V,Vref,=0V,Vdl,=-5V,Vgh,Vgl,Vdh,Vref,Common Driving Pattern,Common,電極的驅動方式,Common,電壓固定不變的驅動方式,Common,電壓不停變動的驅動方式,Direct Driving of TFT,LCDs,DC Bias,of Common,GrayScale,Voltage,V0,V1,V2,V62,V63,V63,V62,V2,V1,V0,1 Frame/1 Line,AC,Driving of TFT,LCDs,V0,V1,V2,V62,V63,V63,V62,V2,V1,V0,Common Waveform,Graylevel,Voltage,1Frame/1 Line,T,100%,V,Vth,Vth,:,液晶的操作臨界電壓,Vcom,:,共通電極訊號位準,正極性,訊號時,光電轉移曲線,負極性,訊號時,光電轉移曲線,Vth,負極性,時,臨界電壓,正極性,時,臨界電壓,5V,3.5V,6.5V,TFT driving curve,T,100%,V,5V,-1.5V,Vth,正極性,訊號時,共通電極訊號位準,負極性,訊號時,共通電極訊號位準,正極性,訊號時,光電轉移曲線,負極性,訊號時,光電轉移曲線,Vth,TFT driving curve,面板極性變化與,Common,電極驅動方式的選用,面板極性變化方式,可使用的,Common,電極驅動方式,Common inversion,固定與變動,Gate inversion,固定與變動,Data inversion,只能使用固定的,Common,電極電壓,Dot inversion,只能使用固定的,Common,電極電壓,面板極性變化與,Common,電極驅動方式的選用,面板極性變化方式,Flick,的現象,Crosstalk,的現象,Common inversion,明顯,垂直與水平方向都容易發生,Gate inversion,不明顯,水平方向容易發生,Data inversion,不明顯,垂直方向容易發生,Dot inversion,幾乎沒有,不易發生,在面板設計上,Cst,有兩种擺放位置,1.,Cst,on Common,2.Cst on Gate,液晶畫素,TFT,Gate Line,Data Line,Cs,液晶畫素,TFT,Common,Gate Line,Data Line,Cs,Cs,Cst on Com,Cst on Gate,Higher Open Ratio,Cst Design(Cst on Com&Cst on Gate),TFT,Cst,Gate-line,Data-line,Via,ITO,Pixel Layout(Cst on Com&Cst on Gate),Cst on Gate/Com,之名稱來自於,Cst,所接的信號來源,依構成電容之層別種類可細分成,MII&MIM,電容設計差異,-,MIM vs.MII,MIM,Cross-View,MII,Cross-View,名詞解釋,:,M metal,金屬,GE/SD/ITO,I Insulator,絕緣層,AS/BP,用來使上述金屬層間之分隔避免之間,Short,Cst on Gate,即使用,ITO/GE,作電容儲存,Pixel,主要組成要素,畫面上一個點為三個,pixel,所組成,(,R,紅,G,綠,B,藍,),而每個,pixel,之組成要素則為,1.,TFT device,主要作用為控制,pixel,信號之傳遞,2.,Cst,主要功用為儲存電荷之用,確保在下一次更新,信號來臨前可將先前之信號儲存於,pixel,內,3.,ITO,與彩色濾光片共同組成上下兩電極板提供電場使兩者之間之,液晶角度變化以控制,pixel,之亮暗程度,TFT Configuration,Cst on Gate,MIM,Cst on Com,MIM,名詞解釋,GE:,1.,掃描線,(,Scan line),決定畫面更新,可控制,AS,層開關之開啟或關閉,2.,作外圍金屬線路之用,避雷針,.,AS:,1.Pixel,之開關,決定,SD,訊號輸入,pixel,裡,來決定,pixel,之亮暗程度,2.,Dummy pattern,mark,numbers,.not for circuit layout.,3.,絕緣層,i.e.Repair Line cross-over pads.,SD:,1.,信號線,(,Data line),決定每個,pixel,需要到達之電壓值決定其亮度,2.,作外圍金屬線路之用,避雷針,.,BP:,1.,電路橋接點,將金屬層藉由,BP,挖,Via,洞將,各層金屬連接,以構成所想要之電路,2.,絕緣層,Dummy pattern,mark,numbers,.not for circuit layout.,ITO:,1.Pixel,之電極板,可用來控制液晶,以決定,pixel,透光程度,2.,作外圍金屬線路串接用,因厚度較薄,通常用來作測試信號間之串接,於後段較易切斷,避免因,cut,線造成過多金屬屑影響電路,Cst on Common&Gate,在驅動電路上的差異,Clc,Cs,Clc,Cs,Common,Common,(,N-1)th,Scan Line,(,N-1)th,Scan Line,Nth Scan,Line,Nth Scan,Line,Cs on Common Mode,Cs on Gate Mode,Cgd,Cgd,液晶,电,容,儲存,电,容,扫,描,电极,资,料,电极,共通,电,極,Mth,Data Line,Mth,Data Line,资,料,电极,扫,描,电极,:,Clc,:Cs,:,Com,:,Cgd,寄生,电,容,液晶,画,素,电,容,:,Clc+Cs,Cst on Common&Gate,的簡單電路,TFT LCD,驱动,波形,(,Cs on Common,Common=DC Bias),1),TFT,LCDs,Driving Waveform,-,Cs on Common,2),TFT,LCDs,Driving Waveform,-,Cs on,Gate,Cst on Common&Gate,在光學上的差異,Cst on Gate,MIM,Cst on Com,MIM,由上圖看出其中的開口率不一樣！,Cst on gate Cst on Common,Result:,1.,設計上的差異,2.,電路驅動的差異性,3.,光學上開口率不一樣,但是爲什麽大多數的存儲電容設計都是採用,Cst on gate,的方式：,1.,Cst,on gate,的開口率,Cst,on Common,開口率,2.,雖然黨下一條,Gate,走綫送出電壓打開下一個,TFT,時會影響到存儲電容上存儲電壓的大小，但是下一條,Gate,走綫打開到關閉的時間很短，如：則很有限！,Thanks!,