COORDINATE INPUT PEN, ELECTRONIC BOARD USING IT, COORDINATE INPUT SYSTEM AND ELECTRONIC BOARD SYSTEM

摘要

PROBLEM TO BE SOLVED: To stably detect a pen position though there is the distortion of display panel, the inclination of a coordinate input pen, or the like by providing a conical infrared diffusing member at the tip part of the coordinate input pen and detecting only beams diffused nearly vertically to the direction of a pen axis by the diffusing member. SOLUTION: A coordinate input pen 13 consists of a light diffusing part 31 receiving an infrared beam 18 scanning on a display panel, a pen tip 32 attached to the tip of the part 31 and an axis part 33. The part 31 is made of material transparent with respect to infrared rays, is nearly conical, and has a rougb surface so as to be capable of scattering an infrared beam 18 upward in the part 31. A photodiode is buried in a plane equivalent to the bottom surface of the cone with the side of a photodetecting surface facing downward. The beam 18 crossing with the pen 13 is scattered by the surface of the conical part 31 at the tip part of the coordinate input pen 13, advances upward as a whole inside of the part 31 and is photodetected by the photodetecting surface of the photodiode.