| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems that an open type ultrasonic sensor can not be used in an environment in which an electrode or the like of a piezoelectric element exposes itself and an explosion-proof property of combustible gas and that shieldability is poor and noise immunity is missing because a case is made of resin or the case has an opening part. SOLUTION: In the ultrasonic sensor, a unimorph vibrator constituted by bonding the piezoelectric element 1 inside a bottom surface of the bottomed cylindrical resin case 2, exposure of an electrode or the like of the piezoelectric element is eliminated as in the conventional open type ultrasonic sensor by mounting a resonator on an external surface of a case of the a vibrator to provide a structure which has a high explosion-proof property, high shieldability and noise immunity. COPYRIGHT: (C)2009,JPO&INPIT
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