METHOD AND APPARATUS FOR COORDINATE INPUTTING CAPABLE OF EFFECTIVELY USING A LASER RAY

A coordinate input apparatus includes light sources, a reflecting member, light receiving members, a signal analyzing mechanism, and a coordinate determining mechanism. Each light source is fixed around a perimeter of a predefined input region at a fixing position different from others and is configured to emit light extending in a deltaic form centered at the fixing position and approximately in parallel to the input region. The reflecting member is fixed around the perimeter of the input region and is configured to recursively reflect the light so that the light returns towards the light sources. The light receiving members are fixed around the perimeter of the input region and are configured to receive the light recursively reflected from the reflecting member and to convert the light into an electric signal. The signal analyzing mechanism analyzes the electric signal to detect a position of an obstacle when the obstacle is placed in the input region and blocks the light. The coordinate determining mechanism calculates a center between coordinates of one and the other edges of the obstacle and determines the center as a coordinate of the position of the obstacle in the input region.