| 摘要 |
PURPOSE:To enable the enlargement of a detection range and the discrimination of invasion order and position, by simple constitution such that a plurality of infrared beams are emitted in time sharing in a pulsated state and beam receiving signal levels due to the reception of emitted beams are detected. CONSTITUTION:An invasion detecting circuit D is constituted of a plurality beam emitters D1-D3 and a beam receiver D4 and a plurality of infrared beams are outputted in time sharing from the beam emitters D1-D3 to be distributed over a wide range and reflected infrared beams from matter O are received by the beam receiver D4. When an invader is present between this circuit D and the matter O, the beam receiving pulse levels synchronous to the beam emission due to the beam receiver D4 change to enlarge a detection range by simple constitution and the discrimination of an invasion order and position can be performed and the reliability of an invasion detecting apparatus is enhanced. |
