COORDINATE INPUT/DETECTION DEVICE, ELECTRONIC BLACKBOARD SYSTEM, COORDINATE DETECTION METHOD AND STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To detect position coordinates in the case of simultaneously indicating plural parts at a low cost.;SOLUTION: In the case that a part of light projected to a coordinate input/detection area 3a is interrupted by insertion of the indication members A and B of respectively different diameter sizes in the coordinate input/detection area 3a, an image forming position and an image forming size on respective photodetectors are detected, the two-dimensional position coordinates of the indication members A and B inserted to the coordinate input/detection area 3a are calculated based on the image forming position or the like and further, the diameter sizes of the light shielding parts of the indication members A and B at the respective two-dimensional position coordinates are calculated based on the image forming size or the like. Thereafter, the two-dimensional position coordinates where the diameter sizes of the light shielding parts of the indication members A and B in the respective photodetectors almost match are extracted as the two-dimensional position coordinates actually indicated by the indication members A and B. Thus, since the position coordinates A' and B' where the diameter sizes do not almost match can be eliminated as the ones obtained by erroneous recognition, the position coordinates in the case of simultaneously indicating the plural parts are detected at a low cost.;COPYRIGHT: (C)2001,JPO