| 摘要 |
PURPOSE:To obtain a signal detection circuit that operates stably even against incidence of disturbance light noise by inputting pulsed optical signals incident upon a light receiving section to a signal discrimination circuit and discriminating and outputting only pulsed optical signals emitted from a light emitting section. CONSTITUTION:A pulse oscillation circuit 1 is connected to a condenser C1 and oscillates pulses of a specified period. The pulse signal is amplified 2 and drives a light emitting element LD. The pulsed optical beam emitted by the element LD is reflected by an object of detection and strikes a light receiving element PT. The pulse signal from the element PT is amplified 4 and discriminated to a specified level by a level discrimination circuit 5, and sent to a signal discrimination circuit 6. When a pulse that does not synchronize with the oscillation pulse of the circuit 1 appears at the output terminal of the circuit 5, this pulse is absorbed in the circuit 1 through a diode 3 and not inputted to a circuit 6. The circuit 6 consists of a one-shot circuit, a gate circuit and an FF circuit, and shapes output of the circuit 5 to a specified pulse width, and inputs to an integration circuit 7. The output of the circuit 7 is waveform shape and outputted through a output circuit 9, and an inversion output circuit 10. |
