Patent ID: 7515141

Claim:
A coordinate input apparatus configured to detect a position on a coordinate input region, comprising: a first sensor unit and a second sensor unit, each associated with one end of an edge of one side of the coordinate input region, wherein the first and second sensor units each have at least two optical units, wherein the at least two optical units includes a light projecting unit configured to project light onto the coordinate input region and a light receiving unit configured to receive incoming light; a detection unit configured to detect angle information representing directions of shadows, wherein shadows are areas light-shielded by two pointing instructions, according to a light amount distribution obtained from the optical units of the first and second sensor units; and a calculation unit configured to calculate coordinates of two positions pointed by the two pointing instructions, by using: 1) a combination of pieces of angle information on the shadows detected by a combination of the optical units of different sensor units; and 2) a combination of pieces of angle information on the shadows detected by a combination of the optical units of a same sensor unit.