US Patent 7628076 Ultrasound sensor

An ultrasound sensor has an ultrasound oscillator which is expandable and contractible in a thickness direction thereof, and a casing which houses therein the ultrasound oscillator. An outer surface of an end portion of the casing is fixed to a mounting member. The side surface of the ultrasound oscillator has at least one of a protrusion portion, a concave portion and an inclined portion, through which one of two end surfaces of the ultrasound oscillator fixedly contacts an inner surface of the end portion of the casing. The side surface of the ultrasound oscillator is substantially parallel with the thickness direction thereof.