| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an optical digitizer capable of detecting a pen-down from both retroreflected light from a retroreflective member provided to a contact pen shaft atop of the pen at a distance from the pen tip and a light shield part at its periphery. <P>SOLUTION: The retroreflective member is mounted above the surface of the pen tip which comes into contact with an input surface within a range having its lower limit in a retroreflective plate mount area of a peripheral frame and its upper limit outside the mount area (upper part) to add pen reflected light information which is sensitive to pen-down behavior to light shield shadow information which is insensitive at a lower part within the retroreflective plate mount area, thereby detecting the pen being put down. More specifically, when the ratio of a light shield level and a retroreflected light level exceeds a certain threshold, the pen-down behavior is detected. Alternatively, the pen-down behavior is detected from temporal variation in quantity of light. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
