# US 6,298,012 B1 · Doubly resonant push-pull flextensional

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- Number: US 6,298,012 B1
- Document ID: US6298012B1
- Status: Granted
- Kind: B1
- Application number: 09/413,057
- Filed: 1999-10-04
- Granted: 2001-10-02
- Earliest claimed: 1999-10-04
- Assignees: The United States of America as represented by the Secretary of the Navy
- Inventors: Kim C. Benjamin
- Web page: https://patentgrep.com/patent/US6298012B1

## CPC

- G10K 9/121: {Flextensional transducers}
- H04R 7/045: {using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion}
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## Abstract

The present invention relates to a flextensional transducer device comprising a multi-resonant shell and push-pull driving system for driving the shell so as to provide at least two tunable resonant modes, thereby increasing the operational bandwidth of the device. The push-pull driving system is formed by four rings of active drive material grouped to operate as two opposing push-pull pairs. The shell has a dog-bone configuration with two arcuately shaped interior web portions joined to the pairs of rings, end sections joined to the interior web portions, and a central concave section which functions as the primary radiating surface. Upon application of a desired current to the push-pull ring pairs, the interior web portions are caused to vibrate, which vibrations are transmitted to the end sections and the central concave section. By raising or lowering the bending stiffness of the interior web portions, the end sections, and the central concave section, one can selectively tune the modal resonance of the shell.

## Claims

### Claim 1

A flextensional transducer device which comprises:
a multi-resonant shell having a dog-bone shape;
push-pull means for driving said shell so as to provide at least two tunable resonant modes, thereby increasing the operational bandwidth of the device;
said push-pull driving means comprising four rings of drive material positioned symmetrically about the midplane of said shell, said rings being grouped to operate as two opposing push-pull pairs; and
a center web joined to said shell and each of said rings being joined to said center web by a respective tie rod.

### Claim 2 (depends on 1)

A flextensional transducer device according to claim 1 further comprising an end plate threadly engaging each respective tie rod, and each said end plate pinning a respective pair of rings against said shell.

### Claim 3 (depends on 2)

A flextensional transducer device according to claim 2 wherein said shell has two arcuately shaped interior web portions and wherein one of said web portions is positioned between a respective pair of rings, whereby said arcuately shaped interior web portions are caused to vibrate when said ring pairs are operated in a push-pull mode.

### Claim 4 (depends on 3)

A flextensional transducer device according to claim 3 wherein said shell has two end sections and a concave central section intermediate of and joined to said end sections and wherein vibration of said interior web portions causes vibration of said end sections and said concave central section.

### Claim 5 (depends on 4)

A flextensional transducer device according to claim 4 wherein said concave central section comprises a primary radiating surface.

### Claim 6

A flextensional transducer device which comprises:
a multi-resonant shell having a first end section, a second end section and a central concave section which functions as the primary radiating surface;
first and second interior web portions joined to said first and second end sections; and
push-pull drives connected to said first and second interior web portions for driving said shell so as to provide at least two tunable resonant modes.

### Claim 7 (depends on 6)

A flextensional transducer device according to claim 6, wherein said push-pull drives comprises a first pair of rings joined to said first interior web portion and a second pair of rings joined to said second interior web portion.