| 摘要 |
An ultrasonic sensor includes a cylindrical outer case with a bottom and a piezoelectric element fixed to the inner side of the bottom portion of the outer case. A ring-shaped inner case having a central hole extending in the axial direction in the central portion thereof is disposed inside the sidewall portion of the outer case. A flat or substantially flat portion is provided around the central hole of the inner case, and a viscoelastic filler is arranged so as to extend from the central hole to the flat or substantially flat portion of the inner case. A tabular member is disposed on the flat or substantially flat portion so as to face the flat or substantially flat portion with the filler interposed therebetween. When the inner case vibrates, shear deformation occurs in the filler interposed between the flat or substantially flat portion and the tabular member since the tabular member is not substantially deformed, and the vibration is reduced by the viscoelastic damping effect.
|
