| 摘要 |
PURPOSE:To execute the position detection even if plural pieces of obstacles exist, by emitting modulated beams whose frequencies are different from each other, from plural light emitting elements, and detecting reflected beams reflected due to a fact that those modulated beams have irradiated the obstacle, with each light receiving element. CONSTITUTION:Modulated beams whose frequencies are different from each other, which is emitted from plural light emitting elements 12 irradiate an obstacle 14 and reflected, and the reflected beams are photodetected by plural light receiving elements 13 provided in accordance with the elements 12. An output of the element 13 detects only a specific modulation frequency by a frequency filter 16 through a current - voltage converting circuit 15. Subsequent ly, it is supplied to a display device 17, and from each detected frequency signal, a position of the obstacle 14 is displayed. Accordingly, even if plural pieces of obstacles 14 exist, its position can be detected, and also, since the modulated beams are used, this system is not influenced by an electromagnetic noise, etc.
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