| 摘要 |
<p>PROBLEM TO BE SOLVED: To effectively prevent mis-detection due to an external disturbance light by providing a supplement any circuit, detecting an external disturbance light from a wave projected by a projector and supplementing a missing part of a waveform, so as to discriminate the presence of a detected object in a sensing area. SOLUTION: A wave projected by a projector 1 is received by a light receiving device 2, and when no detected object exists in a sensing area A and even when an external disturbance light is produced, the light-receiving device 2 is saturated, a control output of a light interrupt detection section 3a of a controller 3 is shut, and it is discriminated that the detected object exists in the sensing area A. Furthermore, even when an external disturbance light is produced repetitively, the similar discrimination is made. A supplementary circuit 4 uses an external disturbance light detection section 4a to detect an external disturbance light, a leading detection section 4b checks an output waveform and a one-shot generating section 4d supplements the missing part of the waveform. Thus, mis-detection is effectively prevented. Furthermore, a time delay gate 4e prevents mis-detections, due to a repetitive external disturbance.</p> |
