| 摘要 |
PURPOSE:To obtain an optical switch with low cost and high performance by providing a detection terminal comprising a light emitting element and a light receiving element blinked by a high frequency oscillation circuit and a referencing light emitting element whose blink period is opposite to that of the light emitting element and a referencing light receiving element, and applying addition/amplification/binarization to the signals of the signal light and the referencing light at the respective light receiving elements. CONSTITUTION:A reference light 13a of an element 12a becomes a light 13a inverting the period of the signal 13 by an inverter 11a with respect to the pulse light of the element 12. The signal light 13 radiates a body to be detected and its reflected light 15 is received by the element 16. The reference light 13a is received by the element 16a. The light is subject to photoelectric conversion, the signals 16c, 16b are added and inputted to a signal processing circuit 17. The summing signal 16d is subject to AC amplification 17a and only the fluctuation range of the signal is amplified, binaryzed (17b) by the threshold level and synchronized with the signal of the oscillation circuit by the circuit 17c, the circuit 17d confirms the pulse number to obtain an output in response to the presence of an object to be detected. Through the constitution above, the photoelectric switch detecting the fluctuation of a minute luminous quantity is obtained.
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