《InCell触摸屏原理培训讲学》由会员分享，可在线阅读，更多相关《InCell触摸屏原理培训讲学（28页珍藏版）》请在金锄头文库上搜索。
1、In-Cell触摸屏原理,2010.3.15,Introduction of touch panel,1. Resistive touch panel 1.1 traditional resistive touch panel (directly glue on LCD module) a. 4/5/6/8-wire resistive touch panel b. digital resistive touch panel (touch switches, matrix) 1.2 integrate resistive touch panel into LCD cell (between t
2、op and bottom glasses) 2. Capacitive touch panel 2.1 capacitance changed by deformation of top glass 2.2 capacitance changed by induced current from finger 2.2.1 surface capacitive touch panel 2.2.2 projective capacitive touch panel 2.2.2.1 detect self capacitance 2.2.2.2 detect mutual capacitance 3
3、. Other touch panel (Infrared, SAW, Electromagnetic, Optical),Resistive touch panel,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film on glass, glass on glass, film on film等结构。,1.1 4-wire resistive touch panel,Low life time (around 1 million times) Low transmissivity (75%-85%) Not resist scratch
4、 Lowest cost Easy detect circuit Works with any stylus,1.2 Incell resistive touch panelsamsung(1),Basic principle: When pressed, the sensor switch is on (conductive column spacer contact sensor electrode) From plan view, at touch point, common electrode contact two sensing lines perpendicular with e
5、ach other respectively,2. Capacitive touch panel 2.1 capacitance changed by deformation of top glass 2.2 capacitance changed by induced current from finger 2.2.1 surface capacitive touch panel 2.2.2 projective capacitive touch panel 2.2.2.1 detect self capacitance 2.2.2.2 detect mutual capacitance,2
6、.1 Capacitive touch panel (压力式),This integrate type has some different structures, includes: Cell gap change type Samsung filed a patent (US20080048994). AUO has made a demo. LC alignment change type Samsung filed patent (US20050094038) very early, but Samsungs demo applied another detect circuit (S
7、ID07 24.3), and Epson made a demo (SID08 55.2) based on Samsungs structure by using LTPS, IPS and active matrix sensor so that improved the performance.,Cell gap change type(1),Samsungs patent (US20080048994) only posed a basic principle, its layer structure and detailed detect method is not shown i
8、n the patent. Though AUO has made a demo, there are very few open materials of its detect principle. They use the same principle: detect the capacitance change between common electrode and sense electrode by cell gap deformation. There are many ways to detect capacitance change, which way Samsung an
9、d AUO used is unknown.,AUO,Samsung,Cell gap change type(2),AUO和LG的压力式内嵌触摸屏样品,LC alignment change typeSamsung(1),Samsungs patent (US20050094038) first proposed this method: Because different LC alignment has different dielectric constant, and when pressed, the LC alignment is changed, so that the LC
10、capacitance changed.,LC alignment change typeSamsung(2),Samsung和Epson的in-cell LC alignment change type TP,Samsung,Epson,2.2.1 Surface capacitive touch panel,Have 2 conductive coatings. Upper conductive coating is the working plane. Lower coating is shielding plane.,Surface capacitive touch panel,Sur
11、face capacitive touch panel principle: Touch point is treated as connecting to ground by a capacitor. The resistor from touch point to 4 corners R1-4 is related to the distance from touch point to 4 corners. The more the distance is, the more the resistor is. When add sine signal on 4 corners, the c
12、urrent at 4 corners I1-4 is inverse proportion to related R1-4. By measuring I1-4, the touch point can be detected.,Surface capacitive touch panel,Long life time (around 100 million times) Higher transmissivity (Can reach 90%) Only work with fingers Higher cost Patent issue Complex detect circuit Fa
13、st response speed,2.2.2投射电容触摸屏(PCT),投射电容触摸屏（projective capacitive touch panel）可分为两种不同的结构：自电容(self capacitive)与互电容(mutual capacitive) 自电容为较早的技术，来源于touch key, 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,Self capacitance,自电容原理为当手接触时，等效为parasitic capacitance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ch
14、arge transfer检测原理。 通过开关依次开合不断对parasitic capacitance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。,Detect self capacitance,Panel layout: generally using diamond pattern, so the capacitor from finger to both ITO layers will be big enough. The detect sequence is, first detect self capacitance at one layer (red), on
15、e line by one line, to get X position, then detect another layer (blue), to get Y position. So this is fake multi-touch.,Projective capacitive touch panel,自电容的多点触摸定位问题：,Mutual capacitance,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,Mutual capacitanc
16、e,Panel 图案,Mutual capacitance,Driving method: At drive layer (red), add pulse signal one line by one line, and other lines connect to ground. At sense layer (blue), detect charge one by one. When all intersection is detected, the most charge decreased intersection is the touch point. This method is true multi-touch. So apple claimed that iphone is the first image sensing touch panel in the world.,上表面和下表面diamond是错开的,模型仿真结果,No touch,Touch,互电容的优点,互电容相对自电容的显著优点： 对地寄生电容对触控检测影响很
