| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To carry out stable detection irrespective of the variations with time in a retroreflection light amount, or of the unevenness in a partial light amount. <P>SOLUTION: An optical coordinate input device detects a light shielding range from a variation (a difference) in the reflected light amount distribution from a retroreflection member and a rate-of-change (a ratio-of-change) to determine coordinates. Data in an initial illumination free state and light amount distribution in illumination are stored, and the variation and the rate-of-change are calculated from the data. If any change point having not more than a prescribed level is detected in the data acquired as initial data, the data is informed as abnormal data. <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
