| 摘要 |
<p>PURPOSE:To make it possible to stably detect a specific ultrasonic receiving wave form while enabling good accurate distance measurement, by mounting a short distance measuring part and a level adjusting part, and measuring a distance on the basis of a receiving signal detected under the adjusting state of the level adjusting part. CONSTITUTION:When the distance between an ultrasonic transmitter 1 and an ultrasonic receiver 2 is measured, the ultrasonic transmitter 1 drives an ultrasonic vibrator 4 through a driver 3 to oscillate an ultrasonic wave. At this time, an emitting signal showing emitting timing is outputted to the counter 6 of the ultrasonic receiver 2. An ultrasonic wave detector 5 converts the received ultrasonic wave to an electric signal. The counter 6 has function for measuring a time elapsed from the emission of the ultrasonic wave and used in measuring a short distance. Further, the short distance mentioned herein may not be one having no an absolute distance unit and contains one proportional to a south distance at relative time intervals. The counter 6 starts count operation by a predetermined clock signal CLK when the emitted signal from the ultrasonic transmitter 1 is inputted. The count value of the counter 6 is inputted to an address converting part 7.</p> |
