| 摘要 |
PURPOSE:To prevent malfunctioning due to an instantaneous ultrasonic noise by adding a delay circuit to a reflected signal outputted with a reflected wave from an object to be detected. CONSTITUTION:Output l of a memory circuit 13 is outputted to output circuits 17 and 18 through a delay circuit 19 having a delay time T. Outputs (o) and (p) of an output discrimination circuit 20 control the output circuits 17 and 18 judging an output (n) of a delay circuit 19 from the output l of the memory circuit 13 and an output (m) of a memory circuit 16 whether it exists within a time range of a gate circuit 7 or that of a gate circuit 8. In other words, a delay function is outputted only when a reflected wave from an object being detected exists continuously within the respective time ranges of the gate circuits 7 and 8 during the delay time T. With such an arrangement, malfunctioning due to an instantaneous ultrasonic noise can be prevented. |
