PULSE TYPE ULTRASONIC SENSOR APPARATUS AND METHOD FOR DETERMINING WAVE TRANSMISSION INTERVAL IN PULSE TYPE ULTRASONIC SENSOR APPARATUS

摘要

PROBLEM TO BE SOLVED: To set a wave transmission interval to be the shortest value in accordance with use conditions of an ultrasonic sensor apparatus. ;SOLUTION: A predetermined time ΔT is set to be not shorter than a period obtained by subtracting a monitoring period Tc from a reflection wave-mixing period tr, and at the same time, not larger than a period obtained by subtracting an ultrasonic wave transmission pulse width tW from the reflection wave-mixing period tr. In each case where an ultrasonic wave transmission interval is set to be (T-ΔT), T, (T+ΔT), detection results of reflection waves in the respective monitoring period Tc are checked. Moreover, the T is increased or decreased by every predetermined value ΔT from an optional value. A time T when the reflection waves are detected is determined as the wave transmission interval only in the case of (T-ΔT) among the three transmission intervals.;COPYRIGHT: (C)1997,JPO