Infrared touch screen is formed by installing the outer frame of the circuit board in front of the display, forming an infrared matrix. When the user touches, their fingers will block the horizontal and vertical infrared rays passing through the position, thereby determining the position of the touch point. Infrared touch screens are inexpensive but susceptible to changes in external light. Surface acoustic wave touch screen uses the reflection and attenuation of sound waves on the glass surface to locate touch points. Surface acoustic wave touch screens have high clarity and are not easily damaged, but the surface needs to be cleaned regularly as dust, oil, and other contaminants can affect touch accuracy.

The basic principle of a touch screen is that when a user touches the touch screen installed at the front end of the display with their fingers or other objects, the touched position (in coordinate form) will be detected by the touch screen controller and sent to the CPU through an interface (such as RS-232 serial port) to determine the input information. The touch screen system mainly includes two parts: a touch screen controller and a touch detection device. The main function of the touch screen controller is to receive touch information from the touch point detection device, convert it into contact coordinates, and send it to the CPU for processing; The touch detection device is installed at the front end of the display, responsible for detecting the user's touch position and transmitting it to the touch screen controller.