| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely recognize a visual field obstacle at the time of releasing security by directly inputting reflected light obtained by reflecting an infrared ray from a projection means for visual field obstacle detection by an obstacle to a light reception means, recognizing that light-receiving output is large at the projection timing and judging the existence of the obstacle. SOLUTION: The infrared rays are projected on respective detection areas 7 and 8 at different projection timing from a projection means for human body detection 1 and the projection means for visual field obstacle detection 2. Reflected light beams from the areas 7 and 8 are inputted to one light reception means 3. When the obstacle exists in the area 7, the infrared ray projected from the projection means for visual field obstacle detection 2 is reflected by the obstacle and is directly made incident on the light reception means 3. At that time, light reception output becomes larger than a regular one. If timing when the output is obtained corresponds to the timing of the projection means for visual field obstacle detection 2, the obstacle is judged to exist in the area 7 becoming the visual field obstacle.</p> |
