AIRBORNE ULTRASONIC SENSOR

摘要

Provided is an airborne ultrasonic sensor capable of making a directivity pattern in a predetermined direction asymmetrical with a simple configuration. The airborne ultrasonic sensor comprises a case having a hollow portion, one end of which opens and the other end of which becomes a closed surface, and a piezoelectric element disposed on the inner side of the closed surface, wherein the closed surface forms a vibration surface. The side surface of the case has at least a region provided by removing part of the side surface from the opening surface side. The closed surface has either one of circular, elliptical, oval, square, and rectangular shapes.