US 11,833,543 B2
Ultrasonic apparatus
Motoyasu Nakao, Nagaokakyo (JP); and Kosuke Watanabe, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Jul. 16, 2019, as Appl. No. 16/512,429.
Application 16/512,429 is a continuation of application No. PCT/JP2018/000271, filed on Jan. 10, 2018.
Claims priority of application No. 2017-011458 (JP), filed on Jan. 25, 2017.
Prior Publication US 2019/0337016 A1, Nov. 7, 2019
Int. Cl. B06B 1/02 (2006.01); B06B 1/06 (2006.01)
CPC B06B 1/0215 (2013.01) [B06B 1/0692 (2013.01); B06B 2201/40 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An ultrasonic apparatus comprising:
a three-terminal ultrasonic transducer including a common electrode, a transmitting electrode, and a receiving electrode independent of the transmitting electrode;
a transmitting circuit to output a driving signal to the transmitting electrode to cause the ultrasonic transducer to transmit ultrasonic waves;
a receiving circuit to receive a receive signal from the receiving electrode; and
a capacitance measuring circuit that measures an electrostatic capacitance of the ultrasonic transducer while being electrically connected to the receiving electrode; wherein
the transmitting electrode is separated from the receiving electrode; and
the capacitance measuring circuit includes:
an alternating-current signal generating circuit to generate an alternating-current signal of a reference amplitude having a frequency different from a resonant frequency of the ultrasonic transducer;
a reference capacitor connected between the alternating-current signal generating circuit and the receiving electrode;
an amplitude measuring circuit to measure an amplitude between the reference capacitor and the receiving electrode; and
a capacitance calculating circuit to calculate the electrostatic capacitance of the ultrasonic transducer based on the amplitude measured by the amplitude measuring circuit and the reference amplitude.