| 摘要 |
An airborne ultrasonic sensor capable of obtaining an asymmetric directivity pattern in a predetermined direction with a simple structure. The airborne ultrasonic sensor includes: a case whose one end is open and another end is a closed surface, so as to have a hollow portion; and a piezoelectric element which is disposed on an inner side of the closed surface, the closed surface being a vibration surface, in which the case has a side surface at least partially provided with a region which is obtained by removing the side surface from an opening surface side. The closed surface has a circular, elliptical, oval, square, or rectangular shape. |
