| 摘要 |
PURPOSE:To allow the titled switch to be hardly affected by external disturbance by inhibiting the inversion of an output signal of a presettable counter so long as a photodetecting element does not receive prescribed numbers of pulse light continuously. CONSTITUTION:A pulse oscillator 1, a light projecting element 2, a projecting element drive circuit 3, a photodetecting element 4, an amplifier 5, a latch circuit 7 and a detection output circuit 8 are components in common to a conventional circuit. A waveform shaping circuit 6 applies waveform shaping an amplified reception signal (c) by a method different from the conventional method. The presettable counter 9 receives the output signals k-m of a counter control circuit 10, outputs detection signals i, j representing whether or not the photoelectric switch receives a pulse light and gives the result to the detection output circuit 8. The counter control circuit 10 presets or resets the output signals i, j of the counter 9 based on the output signals e, j of the latch circuit 7 and the output signals i, j of the double counter 9 synchronously with a delay signal (b) of the oscillation pulse (a) of the latch circuit 7. |
