| 摘要 |
PROBLEM TO BE SOLVED: To provide an obstacle detector enabling dissolution of extension of a reverberation time. SOLUTION: The obstacle detector includes: two transmitting and receiving blocks 7 enabling a transmitting wave and a receiving wave of an ultrasonic wave to a prescribed detection range with a piezoelectric element 1 by having the piezoelectric elements 1 respectively; and a control part 8 for performing detection operation detecting an obstacle in a detection range by controlling each transmitting and receiving wave block 7 respectively. In each transmitting and receiving wave block 7, one electrode of the piezoelectric element 1 contacts to have a continuity with a vibration case comprising a conductive material, and is connected to a subsequent stage circuit through the vibration case. The control part 8 previously performs preliminary operation driving the piezoelectric element 1 of each transmitting and receiving wave block 7 respectively before performing detection operation. The extension of the reverberation time accompanying change of an electric connection state of the electrode of the piezoelectric element 1 due to non-use of a long period and the vibration case is dissolved by preliminary operation to some extent. COPYRIGHT: (C)2009,JPO&INPIT
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