| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a photoelectric sensor capable of surely detecting mutual interference in a short time. SOLUTION: In a photoelectric sensor 10, a light projector 15 and a photosensor 16 are operated in synchronism with each other at a predetermined period. When an outside diagnostic input terminal 21 diagnoses the interference of the photoelectric sensor 10, first a light projection stopping unit stops light projection from the light projector 15. In this state, the photosensor 16 senses the light at the predetermined period. During two periods with a normal light projecting timing, it is discriminated as to whether or not there is incidence of disturbance light. If there is even only one light incidence, incidence is monitored further for five periods. When there was no light incident, a photosensing timing unit 26 shifts a photosensing timing from an original synchronizing signal, thereby detecting photosensing. When it is discriminated that even then there is no possibility of mutual interference, the photosensing timing is further shifted, thus discriminating the incidence of the disturbance light.</p> |
