Ultrasonic transducer, ultrasonic sensor, method of manufacturing ultrasonic transducer, and method of manufacturing ultrasonic sensor
An ultrasonic transducer includes: a support member having an opening section; a diaphragm adapted to cover the opening section; and a piezoelectric member provided to the diaphragm and at least one of expanding and contracting in an in-plane direction in response to application of a voltage, wherein the diaphragm has a concave groove section formed to have a concave shape on a surface on an opposite side to one side exposed to the opening section, and the piezoelectric member is fixed to the diaphragm in an area outside the concave groove section, and disposed to cover the concave groove section so as to be opposed to a bottom of the concave groove section via a space.
1. An ultrasonic transducer comprising:
a support member that has an opening;
a diaphragm supported by the support member, the diaphragm having a first surface and a second surface opposite to the first surface, the first surface having a concavity, the second surface covering the opening; and
a piezoelectric member covering the concavity of the diaphragm so as to have an air gap therebetween, wherein
the second surface of the diaphragm is exposed to the opening,
the piezoelectric member is fixed to the first surface of the diaphragm at a periphery of the concavity, and
when electric power is applied to the piezoelectric member, the concavity of the diaphragm expands toward the opening.
2. The ultrasonic transducer according to 1 , wherein
the piezoelectric member has at least one communicating section adapted to perform air communication between the air gap and an external area.
3. An ultrasonic sensor comprising:
at least one ultrasonic transducer according to claim 1 ; and
at least one second ultrasonic transducer each including
a second support member having a second opening section,
a second diaphragm adapted to cover the second opening section, and
a second piezoelectric member stacked on the second diaphragm, and adapted to convert a displacement of the second diaphragm into an electrical signal, and output the electrical signal.
4. The ultrasonic sensor according to claim 3 , wherein
a plurality of the ultrasonic transducers and a plurality of the second ultrasonic transducers are arranged in a two-dimensional array structure.
5. The ultrasonic sensor according to claim 4 , wherein
the ultrasonic transducers are disposed in a central area of the two-dimensional array structure,
the second ultrasonic transducers are disposed in three or more areas in a periphery of the central area, and
a constant potential wiring connected to a constant potential is disposed between the ultrasonic transducers and the second ultrasonic transducers.
6. The ultrasonic sensor according to claim 3 , further comprising:
a sensor array substrate constituting the support member of the at least one ultrasonic transducer, and the second support member of the at least one second ultrasonic transducer.