Input device for computer with graphical operating surface detects location and/or direction of light beam directed at large screen

摘要

An image pick-up device (30) detects an area larger than the area displayed on a display (18). The image pick-up device detects an electromagnetic beam emitted from a transmitter (40) and produces a signal characterizing the location at which the beam hits a surface and/or the path or direction in which a beam moves on the surface. The image pick-up output is fed to a computer. An actuator (54) sets the intensity that a light spot must have to be detected in the presence of other light sources.