In-Cell触摸屏原理(王丽花).ppt

In-Cell触摸屏原理(王丽花).ppt

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In-Cell触摸屏原理2010.3.15Introductionoftouchpanel1.Resistivetouchpanel1.1traditionalresistivetouchpanel（directlyglueonLCDmodule）a.4/5/6/8-wireresistivetouchpanelb.digitalresistivetouchpanel（touchswitches,matrix）1.2integrateresistivetouchpanelintoLCDcell（betweentopandbottomglasses）2.Capacitivetouchpanel2.1capacitancechangedbydeformationoftopglass2.2capacitancechangedbyinducedcurrentfromfinger2.2.1surfacecapacitivetouchpanel2.2.2projectivecapacitivetouchpanel2.2.2.1detectselfcapacitance2.2.2.2detectmutualcapacitance3.Othertouchpanel（Infrared,SAW,Electromagnetic,Optical）Resistivetouchpanel基本原理：

触摸时，两层ITO互相接触，从而在两层ITO之间形成电阻通路根据上下基板材料，可分为filmonglass,glassonglass,filmonfilm等结构。

1.14-wireresistivetouchpanel在两电极上加5V直流电在ITO均匀电阻平面上形成均匀稳恒电流场在另一面的ITO电极上测量电压根据测得电压值（0-5V）确定触摸点的位置用同样方法测量Y坐标1.14-wireresistivetouchpanelLowlifetime（around1milliontimes）Lowtransmissivity（75%-85%）NotresistscratchLowestcostEasydetectcircuitWorkswithanystylus1.2Incellresistivetouchpanelsamsung

（1）Basicprinciple:

Whenpressed,thesensorswitchison（conductivecolumnspacercontactsensorelectrode）Fromplanview,attouchpoint,commonelectrodecontacttwosensinglinesperpendicularwitheachotherrespectively2.Capacitivetouchpanel2.1capacitancechangedbydeformationoftopglass2.2capacitancechangedbyinducedcurrentfromfinger2.2.1surfacecapacitivetouchpanel2.2.2projectivecapacitivetouchpanel2.2.2.1detectselfcapacitance2.2.2.2detectmutualcapacitance2.1Capacitivetouchpanel（压力式压力式）Thisintegratetypehassomedifferentstructures,includes:

CellgapchangetypeSamsungfiledapatent（US20080048994）.AUOhasmadeademo.LCalignmentchangetypeSamsungfiledpatent（US20050094038）veryearly,butSamsungsdemoappliedanotherdetectcircuit（SID0724.3）,andEpsonmadeademo（SID0855.2）basedonSamsungsstructurebyusingLTPS,IPSandactivematrixsensorsothatimprovedtheperformance.Cellgapchangetype

（1）Samsungspatent（US20080048994）onlyposedabasicprinciple,itslayerstructureanddetaileddetectmethodisnotshowninthepatent.ThoughAUOhasmadeademo,thereareveryfewopenmaterialsofitsdetectprinciple.Theyusethesameprinciple:

detectthecapacitancechangebetweencommonelectrodeandsenseelectrodebycellgapdeformation.Therearemanywaystodetectcapacitancechange,whichwaySamsungandAUOusedisunknown.AUOSamsungCellgapchangetype

（2）AUO和和LG的压力式内嵌触摸屏样品的压力式内嵌触摸屏样品LCalignmentchangetypeSamsung

（1）Samsungspatent（US20050094038）firstproposedthismethod:

BecausedifferentLCalignmenthasdifferentdielectricconstant,andwhenpressed,theLCalignmentischanged,sothattheLCcapacitancechanged.LCalignmentchangetypeSamsung

（2）Samsung和Epson的in-cellLCalignmentchangetypeTPSamsungEpson2.2.1SurfacecapacitivetouchpanelHave2conductivecoatings.Upperconductivecoatingistheworkingplane.Lowercoatingisshieldingplane.SurfacecapacitivetouchpanelSurfacecapacitivetouchpanelprinciple:

Touchpointistreatedasconnectingtogroundbyacapacitor.Theresistorfromtouchpointto4cornersR1-4isrelatedtothedistancefromtouchpointto4corners.Themorethedistanceis,themoretheresistoris.Whenaddsinesignalon4corners,thecurrentat4cornersI1-4isinverseproportiontorelatedR1-4.BymeasuringI1-4,thetouchpointcanbedetected.SurfacecapacitivetouchpanelLonglifetime（around100milliontimes）Highertransmissivity（Canreach90%）OnlyworkwithfingersHighercostPatentissueComplexdetectcircuitFastresponsespeed2.2.2投射电容触摸屏投射电容触摸屏（PCT）投射电容触摸屏（projectivecapacitivetouchpanel）可分为两种不同的结构：

自电容（selfcapacitive）与互电容（mutualcapacitive）自电容为较早的技术，来源于touchkey,touchpad互电容技术由iphone发扬光大，发展迅猛，将逐渐取代自电容类型Selfcapacitance自电容原理为当手接触时，等效为parasiticcapacitance增加，而且自电容检测都是在前端（提供电源端）。

检测原理有很多，可检测电压、电流、电荷，下图为chargetransfer检测原理。

通过开关依次开合不断对parasiticcapacitance进行充电放电，检测放电时通过的电荷，当有手指接触时，流出电荷增加。

DetectselfcapacitancePanellayout:

generallyusingdiamondpattern,sothecapacitorfromfingertobothITOlayerswillbebigenough.Thedetectsequenceis,firstdetectselfcapacitanceatonelayer（red）,onelinebyoneline,togetXposition,thendetectanotherlayer（blue）,togetYposition.Sothisisfakemulti-touch.Projectivecapacitivetouchpanel自电容的多点触摸定位问题：

自电容的多点触摸定位问题：

Mutualcapacitance互电容原理为：

当手指接触时，等效为互电容改变，互电容检测一般是在后端（sense端）。

可以检测电压或者电荷。

下图为电荷检测等效电路。

手指接触后等效为互电容减小，此时读出电荷减小。

模型一MutualcapacitancePanel图案图案MutualcapacitanceDrivingmethod:

Atdrivelayer（red）,addpulsesignalonelinebyoneline,andotherlinesconnecttoground.Atsenselayer（blue）,detectchargeonebyone.Whenallintersectionisdetected,themostchargedecreasedintersectionisthetouchpoint.Thismethodistruemulti-touch.Soappleclaimedthatiphoneisthefirstimagesensingtouchpanelintheworld.上表面和下表面diamond是错开的模型仿真结果NotouchTouch互电容的优点互电容的优点互电容相对自电容的显著优点：

1.对地寄生电容对触控检测影响很小，更适合在集成触摸屏结构2.具有更强的抵抗LCD噪声能力3.可以实现真