SAW Touch Technology: Surface Acoustic Wave
The Surface Acoustic Wave (SAW) technology is one of the most advanced touch screen types. The technology is based on two transducers (transmitting and receiving) placed for the both of X and Y axis on the touch panel. The other important element of SAW is placed on the glass, called reflector. The controller sends electrical signal to the transmitting transducer, and transducer converts the signal into ultrasonic waves and emits to reflectors that are lined up along the edge of the panel. After reflectors refract waves to the receiving transducers, the receiving transducer converts the waves into an electrical signal and sends back to the controller. When a finger touches the screen, the waves are absorbed, causing a touch event to be detected at that point.
IR Touch Technology: Infrared Technology
Infrared Touch Screen is a touch frame which is usually installed in front of the display screen. The frame is integrated with printed circuit board which contains a line of IR-LEDs and photo transistors hidden behind the bezel of the touch frame. Each of IR-LEDs and photo transistors is set on the opposite sides to create a grid of invisible infrared light. The bezel shields the parts from the operation environment while allowing the IR beams to pass through.
Camera Sensing Technology: Optical Sensors
Optical touch screen technology uses two line scanning cameras located at the corners of the screen. The cameras track the movement of any object close to the surface by detecting the interruption of an infra-red light source. The light is emitted in a plane across the surface of the screen and can be either active (infra-red LED) or passive (special reflective surfaces).