Patent US4728844A successfully refreshed from Google Patents.
US4728844A
Expired / Lapsed
US
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Piezoelectric transducer and components therefor
Assignee: Cogent Ltd
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Filing: 1986-07-29
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Granted: 1988-03-01
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Expires: 2006-07-29
Abstract
Abstract A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element extending across the opening has a casing containing a backing material in direct contact with the piezoelectric element. The backing material comprises a polymeric composition which may contain a heavy metal oxide, e.g. BiO, or a metal, e.g. Ni, in particulate form, and/or may contain particles of a material of lower specific gravity than the surrounding composition, the distribution of said particles being such that they are most concentrated in a region remote from the piezoelectric element and are least concentrated or essentially absent in the region immediately adjacent the piezoelectric element.
Inventors
- 👤 Paul Wilson
- 👤 Peter Kent
- 👤 Duncan Stewart
- 👤 Robert Crocker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:58
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/13; H10N; H10N30/00; H10N30/01; H10N30/06; H10N30/30; H10N30/308; Y; Y10; Y10S; Y10S310/00; Y10S310/80
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
93 words
A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element of a piezoelectric plastics material extending across the opening, the casing containing a backing material in direct contact with the piezoelectric element, the backing material comprising a polymeric composition containing particles of a material of lower specific gravity than the surrounding composition, the distribution of said particles being such that they are most concentrated in a region remote from the piezoelectric element and are least concentrated or essentially absent in the region immediately adjacent the piezoelectric element.
Claim 2
Dependent Claim
93 words
A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element of a piezoelectric plastics material extending across the opening, the casing containing a backing material in direct contact with the piezoelectric element, the backing material comprising a polymeric composition containing particles of a material of lower specific gravity than the surrounding composition, the distribution of said particles being such that they are most concentrated in a region remote from the piezoelectric element and are least concentrated or essentially absent in the region immediately adjacent the piezoelectric element.
Claim 3
Dependent Claim
16 words
A piezoelectric transducer according to claim 1 wherein said particles comprise PVdF or a PVdF/TrFE copolymer.
Claim 4
Dependent Claim
20 words
A piezoelectric transducer according to claim 2 wherein the polymeric composition contains also bismuth oxide and nickel in particulate form.
Claim 5
Dependent Claim
51 words
A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element of a piezoelectric plastics material extending across the opening, the casing containing a backing material in direct contact with the piezoelectric element, the backing material comprising a polymeric composition containing bismuth oxide in particulate form.
Claim 6
Dependent Claim
51 words
A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element of a piezoelectric plastics material extending across the opening, the casing containing a backing material in direct contact with the piezoelectric element, the backing material comprising a polymeric composition containing bismuth oxide in particulate form.
Claim 7
Dependent Claim
54 words
A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element of a piezoelectric plastics material extending across the opening, the casing containing a backing material in direct contact with the piezoelectric element, the backing material comprising a polymeric composition containing nickel and bismuth oxide, each in particulate form.
Claim 8
Dependent Claim
54 words
A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element of a piezoelectric plastics material extending across the opening, the casing containing a backing material in direct contact with the piezoelectric element, the backing material comprising a polymeric composition containing nickel and bismuth oxide, each in particulate form.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |