How does an infra-red touch screen detect touch inputs?

An infra-red touch screen operates by utilizing an array of infra-red light beams that are projected across the surface of the screen. When a user touches the screen, their finger or hand interrupts the pathway of the infra-red beams, creating a break in the signal. The touch screen then registers this break, allowing it to determine the location of the touch on the screen. This method is effective because it can accurately detect touch without physical contact required on the screen's surface, leading to reduced wear and tear and allowing for use with gloved hands or styluses that do not conduct electricity.

The other methods mentioned, such as measuring pressure or detecting electrical signals from the user's body, are not employed by infra-red touch screens, as these operate on an optical detection principle rather than relying on conductivity or pressure sensitivity.