US 6,604,433 B1Granted

Ultrasonic transducer and ultrasonic flowmeter

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsNaoko Azuma, Akihisa Adachi, Masahiko Hashimoto, Tooru Ninomiya, Kenzo Ohji

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Abstract

The present invention provides an ultrasonic transducer having uniform characteristics. Because the characteristics of a pair of ultrasonic transducer are equalized with each other, measuring accuracy of an ultrasonic flowmeter can be improved. Electrical connection from an electrode surface 13 of a piezoelectric body 11 to an external electrode is achieved not by soldering but by an electroconductive elastic body 16. As a result, variations of the frequency characteristics due to thermal load on the piezoelectric body 11 can be reduced, and this makes it possible to obtain an ultrasonic transducer with uniform characteristics, and measuring accuracy of an ultrasonic flowmeter using a pair of the ultrasonic transducer can be improved.

Claims12

Dependent claims

An ultrasonic transducer for transmitting and receiving ultrasonic waves, comprising:

a piezoelectric body having two opposed surfaces;
first and second electrodes respectively on said two opposed surfaces;
an electroconductive elastic body having flat opposed surfaces;
and
an external electrode unit for transmitting an electric signal to said piezoelectric body, said external electrode unit comprising:
a first portion that is electrically connected to one of said surfaces of said piezoelectric body via said electroconductive elastic body and said first electrode, wherein substantially the entire face of one of said flat opposed surfaces of said electroconductive elastic body is in contact with substantially the entire face of a flat surface of said first portion, and substantially the entire face of the other of said flat opposed surfaces is in contact with substantially the entire face of a flat surface of said first electrode;
a second portion that is secured to said second electrode and is electrically connected to the other of said surfaces of said piezoelectric body via said second electrode;
a third portion that is mechanically connected to, but electrically insulated from, said second portion;
securing means for securing said first portion to said third portion by compressing said electroconductive elastic body, thereby sandwiching said electroconductive elastic body under pressure between said first portion and said first electrode, and
means for biasing said first portion toward said second portion with a compressive force exerted by said electroconductive elastic body, thereby applying biasing forces to electrical connecting portions between said electroconductive elastic body and said first electrode, and between said electroconductive elastic body and said first portion.

7 more elements

An ultrasonic flowmeter, comprising:

a flowrate measuring unit;
a pair of ultrasonic transducers each comprising a piezoelectric body having two opposed surfaces;
first and second electrodes respectively located on said two opposed surfaces;
an electroconductive elastic body having flat opposed surfaces;
and
an external electrode unit for transmitting an electric signal to said piezoelectric body, said external electrode unit comprising:
a first portion that is electrically connected to one of said surfaces of said piezoelectric body via said electroconductive elastic body and said first electrode, wherein substantially the entire face of one of said flat opposed surfaces of said electroconductive elastic body is in contact with substantially the entire face of a flat surface of said first portion, and substantially the entire face of the other of said flat opposed surfaces is in contact with substantially the entire face of a flat surface of said first electrode;
a second portion that is secured to said second electrode and is electrically connected to the other of said surfaces of said piezoelectric body via said second electrode;
securing means for securing said first portion to said second portion, which is mechanically connected to, but insulated from, said second portion, by compressing said electroconductive elastic body, thereby sandwiching said electroconductive elastic body under pressure between said first portion and said first electrode, and
means for biasing said first portion toward said second portion with a compressive force exerted by said electroconductive elastic body, thereby applying biasing forces to electrical connecting portion between said electroconductive elastic body and said first electrode, and between said electroconductive elastic body and said first portion;
said pair of ultrasonic transducers located on said flowrate measuring unit;
a driving circuit for driving one of said ultrasonic transducers for detecting ultrasonic pulse;
a receiving detection circuit connected to the other of said ultrasonic transducer and for detecting ultrasonic pulse;
a timer connected to the driving circuit for measuring propagation time of an ultrasonic pulse;
and
an arithmetic unit for calculating flowrate from output of said timer.

13 more elements

Dependencies are inferred from the claim text.