| 摘要 |
PROBLEM TO BE SOLVED: To surely detect the entrance of a human being to the vicinity of a light projecting area and to weaken the optical power of light to a level safe for a human body. SOLUTION: An entrance detection part 112 is installed behind an image projection part 111 with a screen 102 as reference, and monitors the entrance of a human being 103 to a monitoring area 122 adjacent to an entrance enabled range out of the boundary surface of the projecting area 121 of a laser beam projected from the image projection part 111 to the screen 102. When the entrance of the human being 103 to the monitoring area 122 is detected by the entrance detection part 112, the image projection part 111 lowers the level of the optical power of the laser beam to the level safe for the human body within reaction time Tdwn 1. COPYRIGHT: (C)2006,JPO&NCIPI
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