From the technical principle to distinguish the touch screen, can be divided into five basic types: vector pressure sensing technology touch screen, resistance technology touch screen, capacitive technology touch screen, infrared technology touch screen, surface acoustic technology touch screen. < BR > The touch screen of vector pressure sensing technology has withdrawn from the historical stage; Infrared touch screen is cheap, but its frame is fragile, easy to produce light interference, distortion under curved surface; The design of capacitive touch screen is reasonable, but the problem of image distortion is difficult to be solved fundamentally. The positioning of the resistive touch screen is accurate, but its price is quite high, and it is easy to scratch; < BR > Surface acoustic touch screen solves the various defects of the previous touch screen, clear and not easy to be damaged, suitable for various occasions, the disadvantage is that if there are water droplets and dust on the surface of the screen will make the touch screen become dull, or even do not work. < BR > According to the working principle of touch screen and the medium of transmitting information, touch screen is divided into four types, they are resistance type, infrared type, capacitance induction type and surface acoustic wave type.