| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely and rapidly detect a human body coming from afar. SOLUTION: In this heat ray sensor, a human body in a specified detection area in a passage is detected by each detection beam through an optical system 111 and a pair of optical system 121, using each detection signal from an infra- red detecting element 112 and a pair of infra-red detecting elements 122 provided to the optical system 111 and the pair of optical systems 121, respectively. Width of each detection beam is set to be approximately constant in a direction of width of the passage. The optical systems 111, 121 are set such that the focal length becomes longer and the open area ratio of the optical system to the focal length becomes larger in the optical system capable of passing farther detection beam in a progressing direction of the passage, that is, the optical system 121, than in another optical system, that is, the optical system 111.</p> |
