Generally, the working part of an LCD touch screen monitor is composed of three parts: two layer of stransparent resistive conductor, an isolation layer and electrodes between the two conductors. The resistive conductor layer is generally made of resistive materials, such as indium tin oxide plated on the substrate, plastic for the upper substrate, and glass for the lower substrate. The isolation layer is a viscous insulating liquid material, such as polyester film. The conductivity of the electrode is about 1000 times as that of ITO.
When touching the LCD touch screen display, the upper and lower conductor layers are equivalent to the resistance network. When increasing the voltage of a certain layer of the electrode, a voltage gradient is formed on the network. If there is an external force that brings the upper and lower layers into contact at one point, the voltage of the contact point can be measured at the other layer where no voltage is applied to the electrode, and the coordinates of the contact point can be obtained. If a voltage is added to the electrode on the top layer, a voltage gradient is formed on the top conductor layer. And if there is an external force that makes the upper and lower layers contact at a certain point, the voltage at the contact point can be measured on the bottom layer. Then according to the distance relations between the voltage and the electrodes, the X coordinate can be defined here. Then switch the voltage to the bottom electrode, and measure the voltage at the contact point on the top layer to determine the Y coordinate.