| 摘要 |
PURPOSE:To eliminate the influence of interference, by inserting a gate circuit to the input or output side of the Schmitt circuit by which a trigger pulse is obtained from a detection output and by turning on this gate circuit only when a predetermined number or more of trigger pulses is obtained under the steady state in respect to time. CONSTITUTION:Gate circuit 11 is inserted between detecting circuit 5 and Schmitt circuit 6, and this gate circuit 11 is controlled by gate controlling signal D obtained from control circuit 12. Controlling signal D obtained from control circuit 12 is obtained as the signal to turn on gate circuit 11 when a predetermined number or more of detection outputs based on the reflection wave from the target obtained from detecting circuit 5 is obtained under the steady state in respect to time by the counter in control circuit 12. As a result, the interference detection output from detecting circuit 5 is not given to Schmitt circuit 5, and processing circuit 7 is not affected by the interference detection output. |
