To reduce the deterioration of accuracy even when light quantity distribution detected by a CCD sensor is changed so that light quantity is reduced at the time of input (due to the influence of reflection on an input surface).
The recursive reflected light cutoff detection type coordinate input device is provided with a memory means for storing a plurality of light quantity distributions shielded from light by a pointing tool on a prescribed input position and detected by a light receiving means and a light quantity distribution selection means for comparing the light quantity distribution in an input area shielded from light by the pointing tool with the plurality of light quantity distributions stored in the memory means and selecting one of the light quantity distributions. An angle is detected from a variation in the light shielded area shielded by the pointing tool from the light quantity distribution selected by the light quantity distribution selection means to calculate coordinates.
Yuichi Uchio