Nowadays electronic products, such as mobile phones, computers and even tablets, have been upgraded to touch displays. Why do we need to design this way? Because the touch display is large and stylish enough, many manufacturers are making the display bigger and bigger to meet people's larger demand for displays. So what is the working principle of touch display?
Touch Screen display (Touch Screen) allows users to operate the host just by gently touching the icons or text on the computer display with their fingers. This gets rid of keyboard and mouse operations and makes human-computer interaction more straightforward. It is mainly used in public places lobby information inquiry, leadership office, electronic games, songs and orders, multimedia teaching, air tickets/train ticket pre-sale, etc.
The working part of a typical touch screen is generally composed of three parts, two transparent resistive conductor layers, an isolation layer between the two conductors, and electrodes. The resistive conductor layer is made of a resistive material, such as steel tin oxide (ITO) applied 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 a polyester film. The electrode is made of materials with excellent conductivity (such as silver powder ink), and its conductivity is about 1000 times that of ITO. When the touch screen is working, the upper and lower conductor layers are equivalent to the resistor network. When a certain layer of electrodes is applied to voltage, a voltage gradient will be formed on the network. If there is an external force that causes the upper and lower layers to contact at a certain point, the voltage at the contact point can be measured on the other layer where the electrode has not been applied, so that the coordinates at the contact point can be known.
Nowadays, in many PDA applications, the touch screen is used as an input device, and there are special chips for the control of the touch screen. Obviously, the touch screen control chip needs to accomplish two things: one is to complete the switching of electrode voltage; the other is to acquire the voltage value at the contact point.
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