Ultrasonic transducer and ultrasonic flow meter including ultrasonic transducer
View Patent ↗An ultrasonic transducer comprises a metal plate; an acoustic matching member fastened to one of surfaces of the metal plate, a piezoelectric substrate which is fastened to the other surface of the metal plate and generates a vibration; and an insulating damping member covering a surface of the piezoelectric substrate which surface is on an opposite side of a surface fastened to the metal plate; wherein a thickness of the insulating damping member is set to a length which is n/2 of a wavelength of the vibration propagating through the insulating damping member.
1. An ultrasonic transducer comprising:
a metal plate;
an acoustic matching member fastened to one of surfaces of the metal plate;
a piezoelectric substrate which is fastened to the other surface of the metal plate and generates a vibration; and
an insulating damping member covering a back surface of the piezoelectric substrate which surface is on an opposite side of a surface fastened to the metal plate;
wherein a thickness of the insulating damping member is set to a length which is n/2 of a wavelength of the vibration propagating through the insulating damping member.
2. An ultrasonic transducer comprising:
a metal plate;
an acoustic matching member fastened to one of surfaces of the metal plate;
a piezoelectric substrate which is fastened to the other surface of the metal plate and generates a vibration;
an insulating damping member covering a back surface of the piezoelectric substrate which surface is on an opposite side of a surface fastened to the metal plate; and
a support section which is in contact with a back surface of the insulating damping member which surface is on an opposite side of a surface covering the piezoelectric substrate, the support section having a higher density than the insulating damping member;
wherein a thickness of the insulating damping member is set to a length which is (2n−1)/4 of a wavelength of the vibration propagating through the insulating damping member.
3. The ultrasonic transducer according to claim 1 , wherein the metal plate has a flat plate shape.
4. The ultrasonic transducer according to claim 1 , wherein the metal plate has a flanged container shape including a tubular side wall, a top portion covering an opening at one end of the side wall, and a flanged portion protruding outward from the other end of the side wall;
wherein the acoustic matching member is fastened to one of surfaces of the top portion;
the piezoelectric substrate is fastened to the other surface of the top portion, in an inner space of the side wall; and
the insulating damping member covers a back surface of the piezoelectric substrate which surface is on an opposite side of a surface fastened to the top portion.
5. The ultrasonic transducer according to claim 1 ,
wherein the insulating damping member unitarily covers the back surface of the piezoelectric substrate, a side wall of the piezoelectric substrate, and a portion of the metal plate which portion is other than a portion fastened to the acoustic matching member and a portion fastened to the piezoelectric substrate.
6. An ultrasonic flow meter comprising:
the pair of ultrasonic transducers according to claim 1 , which mutually transmit and receive an ultrasonic pulse;
a fluid passage member to which the pair of ultrasonic transducers are mounted such that the ultrasonic transducers are apart from each other;
a transit time measuring section for measuring time for which the ultrasonic pulse propagates between the pair of ultrasonic transducers; and
a calculation section for calculating a flow of a measurement target fluid based on the time measured by the transit time measuring section.
7. The ultrasonic transducer according to 2 , wherein the metal plate has a flat plate shape.
8. The ultrasonic transducer according to 2 , wherein the metal plate has a flanged container shape including a tubular side wall, a top portion covering an opening at one end of the side wall, and a flanged portion protruding outward from the other end of the side wall;
wherein the acoustic matching member is fastened to one of surfaces of the top portion;
the piezoelectric substrate is fastened to the other surface of the top portion, in an inner space of the side wall; and
the insulating damping member covers a back surface of the piezoelectric substrate which surface is on an opposite side of a surface fastened to the top portion.
9. The ultrasonic transducer according to 2 , wherein the insulating damping member unitarily covers the back surface of the piezoelectric substrate, a side wall of the piezoelectric substrate, and a portion of the metal plate which portion is other than a portion fastened to the acoustic matching member and a portion fastened to the piezoelectric substrate.
10. An ultrasonic flow meter comprising:
the pair of ultrasonic transducers according to claim 2 , which mutually transmit and receive an ultrasonic pulse;
a fluid passage member to which the pair of ultrasonic transducers are mounted such that the ultrasonic transducers are apart from each other;
a transit time measuring section for measuring time for which the ultrasonic pulse propagates between the pair of ultrasonic transducers; and
a calculation section for calculating a flow of a measurement target fluid based on the time measured by the transit time measuring section.