Wireless input system for computer using pen position detection

Claim 1

A wireless input device for a computer comprising: a pen-type input device having a source of light capable of transmitting light pulses, an input device body including two angle detecting sections spaced apart by a given distance, each angle detecting section being located at a fixed point and including a rotatably-supported, substantially cylindrical frame, a lens attached to the frame for focusing incident light from the pen-type input device, a light receiving element in the form of a two-division photodetector attached to the frame opposite to the lens for detecting incident light focused by the lens, rotating means for rotating the frame toward a direction of incident angle of the incident light so that a difference in quantities of the incident light received by the two-division photodetector is cancelled to zero, and rotation position detecting means for detecting a rotation position of the frame upon its rotation toward the direction of the incident angle of the incident light, and a calculating section for calculating a position of the pen-type input device from the incident light detected by the two angle detecting sections, wherein said calculating section calculates the position of the pen-type input device on the basis of the two incident angles detected by the two angle detecting sections and the distance between the fixed points of the two angle detecting sections.