Data input device using coordinate system defined by refracted infra-red light grid

摘要

An input device for a processing system comprising a transparent sheet (3) to which refracting strips (4) are attached. The refracting strips (4) define a rectangular boundary. Behind the transparent sheet (3) adjacent to the refracting strips (4) are transmitting (1) and receiving (2) Light Emitting Diodes (LED's). The light from a transmitting LED (1) travels through the transparent sheet (3) into the refracting strip (4), across the opposite face of the transparent sheet (3) into the cooperating refracting strip (4) back through the transparent sheet (3) and into the receiving LED (2). The LED pairs are arranged to form a grid pattern so that breaking of two perpendicular beams defines a coordinate, which is processed by a device to perform a desired function.