| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultrasonic sensor which suppresses vibration of a housing section where a piezoelectric element for performing only reception of an ultrasonic wave is housed, stabilizes the directivity of the ultrasonic wave more, and improves a reverberation characteristics. Ž<P>SOLUTION: A piezoelectric element 26a is a type of element which transmits an ultrasonic wave whose center frequency is 72 kHz, and the height of a vibration case and a uniting section 23 are set so that the ratio of the height of the vibration case 20 and the thickness of the uniting section 23 becomes 2:1 when the frequency is set. As a result, the vibration of the housing section 21b is suppressed, the directivity of the ultrasonic wave is more stabilized, and the reverberation characteristics are improved. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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