| 摘要 |
PURPOSE:To obtain a photoelectric switch with high reliability and fast response speed with simple circuit constitution by giving a signal of an oscillation circuit to a drive circuit of a projective element and also to a latch circuit and latching a signal from a photoelectric converting circuit in the timing when the projective element is turned on to off. CONSTITUTION:The oscillating circuit generates a square wave 4- to drive the projective element and transmit a modulation light. A projective element drive circuit receives this signal so as to turn on/off the projective element 21 and the modulation light is transmitted from the projecting element 21. When an object to the detected exists, the modulation light is reflected on the object to be detected, enters a photodetector 20 and the light is converted into an electric signal by a photoelectric converting circuit and the result enters a differentiation circuit. Then a DC bias is given to a signal 4-h by a bias circuit so as to boost the entire level of the signal to a level close to an input threshold level of the latch circuit. A signal 4-i outputted from the bias circuit enters the latch circuit and latched in the timing when a signal 4-g from the oscillating circuit changes from the ON to the OFF state.
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