| 摘要 |
PURPOSE:To prevent the malfunction due to noise in external light, by operating the switch as a virtual synchronizing type in which an oscillator synchronized with the output of a photodetection circuit at the photodetector side, in a photoelectric switch of projected light reception type. CONSTITUTION:A light emitting circuit 1 of a projector A is modulated with pulse signal from the 1st oscillation circuit 5, this modulated light is received at a photodetection circuit 2 of a photodetector B, and the output is input to a signal processing circuit 3. The circuit 3 amplifies 9 the output of the circuit 2 for level discrimination 10, and the output is input to a D type FF7. The output of the circuit 10 compulsively synchronizes the 2nd oscillation circuit 6 and the time-delay capacitor of the circuit 6 is rapidly charged/discharged. The oscillation frequency of the circuit 6 is set lower than that of the circuit 5, and the circuit 6 is synchronized with the output of the circuit 11 when a control terminal 14 is at L level, and the output of the circuit 6 is input as the clock to a DFF7 via an inverting circuit 8. The output of DFF7 is input to an output circuit 4 via the integrating circuit 11 and a wave shape circuit 12. When the control terminal 14 is at H level, the synchronizing input to the circuit 6 is interrupted. |
