Infrared

Infrared touch screens are based on light beam interruption technology. Instead of an overlay on the surface, a frame surrounds the display. The frame has light sources, or light emitting diodes (LEDs) on one side and light detectors on the opposite side, creating an optical grid across the screen. When an object touches the screen, the invisible light beam is interrupted.

Disadvantage

Since the infrared beams are a little in front of the display, touch is activated even before the user actually touches the display, causing parallax errors.