| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to perform frequency adjustment without requiring a high level technique without generating fatigue deterioration of a case material and without transforming an oscillation plate by making a bottom part of a case of a bottomed cylindrical shape into the oscillation plate and providing a cut part for the frequency adjustment in the neighborhood of a stress concentration part of the case and an area except for the oscillation plate area. SOLUTION: A sensor case 13 for storing a piezoelectric element 12 of a ultrasonic wave sensor is formed into a bottomed cylindrical shape whose rear side is opened by a metallic material such as aluminum. The sensor case 13 has a bottom face at a front edge of a barrel part 14 of an almost cylindrical shape, this bottom face is made into an oscillation plate 15 of a film shape for generating vibration and receiving a reflected wave, and a step part 17 is provided around a rear edge inner peripheral surface of the barrel part 14. When a frequency is different from a designed value, a cutting tool is used, the inner peripheral surface of the barrel part 14 of the sensor case 13 is cut and a groove-shaped cut part 19 is provided. This frequency can be adjusted by changing a width or a depth of this cut part 19.
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