Touch screen

A touch screen is a input device that allows the user to interact with the computer by touching the display screen.

Often this uses beams of infrared light that are projected across the screen surface. Interrupting the beams generates an electronic signal identifying the location of the screen. Software interprets the signal and performs the required operation.

The HP 150 was among one of the world's earliest commercialized touch screen computers. It actually has not a touch screen in the strict sense, but a 9" Sony CRT surrounded by infrared transmitters and receivers which detect the position of any non-transparent object on the screen.

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