US4482835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiphase backing materials for piezoelectric broadband transducers
Assignee: Systems Research Laboratories Inc
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Filing: 1983-05-09
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Granted: 1984-11-13
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Expires: 2003-05-09
Abstract
Abstract An acoustical transducer is provided with an acoustically absorbant backing material having an acoustical impedance precisely matching the impedance of the piezoelectric element in the transducer. The backing material is a multiphase mixture of selected materials, such as a low melting point alloy (InPb) and one or more powders having high impedance characteristics (tungsten and copper). The slope of the curve impedance versus volume fraction of the backing components is low, thus allowing the impedance of the material to be precisely controlled. The backing material is preferably electrically conductive and is fuzed to one surface of the piezoelectric element to further improve the output characteristics of the transducer.
Inventors
- 👤 Yoseph Bar-Cohen
- 👤 David A. Stubbs
- 👤 Wally C. Hoppe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:08
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/16; G10K11/162; G10K11/165; G10K11/002
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
109 words
In an acoustical transducer comprising a piezoelectric crystal having an electrically conductive surface plated thereon, an absorbant backing material placed against one surface of said crystal for dampening the oscillations thereof, and a housing for supporting the crystal and backing material, the improvement characterized by said backing material comprising a mixture of low melting point metal powder having a low acoustical impedance relative to said crystal to form a matrix into which is evenly distributed one or more metallic powders having a relatively high acoustical impedance, one of which is tungsten, said mixture formed into a cohesive solid having an acoustical impedance precisely matching the impedance of said crystal.
Claim 2
Dependent Claim
109 words
In an acoustical transducer comprising a piezoelectric crystal having an electrically conductive surface plated thereon, an absorbant backing material placed against one surface of said crystal for dampening the oscillations thereof, and a housing for supporting the crystal and backing material, the improvement characterized by said backing material comprising a mixture of low melting point metal powder having a low acoustical impedance relative to said crystal to form a matrix into which is evenly distributed one or more metallic powders having a relatively high acoustical impedance, one of which is tungsten, said mixture formed into a cohesive solid having an acoustical impedance precisely matching the impedance of said crystal.
Claim 3
Dependent Claim
14 words
The transducer as claimed in claim 1 wherein said backing material is electrically conductive.
Claim 4
Dependent Claim
17 words
The transducer as claimed in claim 1 wherein said backing material is fuzed to said crystal plating.
Claim 5
Dependent Claim
21 words
The transducer as claimed in claim 1 wherein said backing material is in acoustical and electrical contact with said crystal plating.
Claim 6
Dependent Claim
24 words
The transducer of claim 1 wherein said low melting point metal powders have a melting point less than the Curie temperature of said crystal.
Claim 7
Dependent Claim
110 words
In an acoustical transducer comprising a piezoelectric crystal having an electrically conductive surface plated thereon, an absorbant backing material placed against one surface of said crystal for dampening the oscillations thereof, and a housing for supporting the crystal and backing material, the improvement characterized by said backing material comprising a mixture of a low melting point powder of InPb alloy having a low acoustical impedance relative to said crystal to form a matrix into which is added one or more powders of tungsten and copper having a high acoustical impedance relative to said crystal to form a cohesive solid having an acoustical impedance closely matching the impedance of said crystal.
Claim 8
Dependent Claim
110 words
In an acoustical transducer comprising a piezoelectric crystal having an electrically conductive surface plated thereon, an absorbant backing material placed against one surface of said crystal for dampening the oscillations thereof, and a housing for supporting the crystal and backing material, the improvement characterized by said backing material comprising a mixture of a low melting point powder of InPb alloy having a low acoustical impedance relative to said crystal to form a matrix into which is added one or more powders of tungsten and copper having a high acoustical impedance relative to said crystal to form a cohesive solid having an acoustical impedance closely matching the impedance of said crystal.
Claim 9
Dependent Claim
110 words
In an acoustical transducer comprising a piezoelectric crystal having an electrically conductive surface plated thereon, an absorbant backing material placed against one surface of said crystal for dampening the oscillations thereof, and a housing for supporting the crystal and backing material, the improvement characterized by said backing material comprising a mixture of about 50% InPb 50--50 having size of less than 44 microns to form a matrix into which is added about 30% tungsten, having a size of less than 150 microns, and about 20% copper, having a size of less than 44 microns, to form a cohesive solid having an acoustical impedance closely matching the impedance of said crystal.
Claim 10
Dependent Claim
110 words
In an acoustical transducer comprising a piezoelectric crystal having an electrically conductive surface plated thereon, an absorbant backing material placed against one surface of said crystal for dampening the oscillations thereof, and a housing for supporting the crystal and backing material, the improvement characterized by said backing material comprising a mixture of about 50% InPb 50--50 having size of less than 44 microns to form a matrix into which is added about 30% tungsten, having a size of less than 150 microns, and about 20% copper, having a size of less than 44 microns, to form a cohesive solid having an acoustical impedance closely matching the impedance of said crystal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-13 | 1988-05-14 | 1988-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-13 | 1992-05-14 | 1992-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-13 | 1996-05-14 | 1996-11-13 | $7700.00 | Window Closed / Lapsed |