| 摘要 |
PURPOSE:To detect exactly a distance without being influenced by a reflection factor of a body to be detected, by making a switch contain plural photodetecting means for outputting a signal of a level corresponding to an incident light quantity, when a position of the body to be detected, and an operating means for executing an operation processing related to an output from the photodetecting means. CONSTITUTION:A light which has been transmitted in optical fibers 26a, 26b is made incident to photodetectors 27a, 27b being photodetecting means. The electrodes 27a, 27b output a signal of a level corresponding to an incident light quantity. This output is amplified by amplifying circuits 28a, 28b, respectively, and voltages V1, V2 are inputted to an operating circuit 29, respectively. In the operating circuit 29, an operation for deriving the V1/V2 is executed. An output of the operating circuit 29 is provided to a non-inversion terminal of a comparing circuit 30, and to an inversion terminal of the comparing circuit 30, a reference voltage VC is applied. An output from the comparing circuit 30 is connected to, for instance, a display device, and whether a body to be detected 24 has been detected or not, etc. are displayed.
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