| 摘要 |
PURPOSE:To avoid a large size of a device for a multi-optical axis photoelectric switch by providing the hysteresis individually to the detection signal of each photodetecting circuit through a common circuit when the photodetecting signal of the multi-optical axis photoelectric switch consisting of plural pairs of projectors and photodetectors is converted into a binary signal. CONSTITUTION:A multi-optical axis photoelectric switch which detects the height of an object 20 carried on a conveyer line is provided with a projection part 10 containing plural light emitting diodes, a photodetection part 12 containing photoreceptors set at the positions opposite to optical axes 18a-18d, and a control CT part 14. The scans are repeated at the part 12 to detect individually whether the light is cut by the object 20 or not. The detection signals obtained from the scans are converted into serial signals and compared successively with the threshold value to be stored in the form of binary signals of H and L levels. The threshold value is changed according to the level of the binary signal delivered from a memory means compared with the threshold value obtained in a scan mode. Then the compared binary signal is supplied to the part 14. The part 14 stores the input signal and provides the hysteresis individually to the detection signal of each photodetector to convert these detection signals into parallel signals. These parallel signals are delivered through terminals 26a-26d.
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