Patent US4178577A successfully refreshed from Google Patents.
US4178577A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low frequency hydrophone
Assignee: United States Department of the Navy
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Filing: 1978-02-06
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Granted: 1979-12-11
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Expires: 1998-02-06
Abstract
Abstract A pressure-balanced hydrophone having a low cut-off frequency which inclu a pair of piezo-ceramic tubes, wired in series, and having one end of each tube secured to a metal block in the center. The second end of one of the ceramic tubes is covered by means of a solid metal end cap and the second end of the other ceramic tube is covered by a porous sintered metal end cap. The unit is enclosed in an elastomeric cylindrical boot which is closed at the open end by a metallic disc. A pair of fill plugs are provided to fill the interior and the exterior of the piezo-ceramic tubes with a suitable oil. The unique feature of subject device is that a plurality of pores in the porous sintered metal end cap act as a plurality of capillaries for pressure balancing and thus make the hydrophone insensitive to hydrostatic pressure variations.
Inventors
- 👤 Hector J. Cini
- 👤 Theodore J. Meyers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:42
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/06; B06B1/0644; B06B1/0655
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
178 words
A pressure-balanced acoustic transducer having a low cut-off frequency in a liquid medium comprising: a plurality of piezo-ceramic tubes being connected together forming a unit with one end of one of said plurality of piezo-ceramic tubes forming a first open end of said unit and one end of another one of said plurality of piezo-ceramic tubes forming a second open end of said unit; a solid cap means being secured to the first open end of said unit; a sintered metal cap means having a plurality of pores therein, being secured to the second open end of said unit; a flexible boot for housing said unit, said flexible boot having an open end; means for covering said flexible boot at the open end thereof; a fluid for filling said flexible boot and said unit of said plurality of piezo-ceramic tubes; means for filling said flexible boot and said unit of said plurality of piezo-ceramic tubes with said fluid; and means for extracting voltage signals responsive to an acoustic wave impinging upon said acoustic transducer in the liquid medium.
Claim 2
Dependent Claim
178 words
A pressure-balanced acoustic transducer having a low cut-off frequency in a liquid medium comprising: a plurality of piezo-ceramic tubes being connected together forming a unit with one end of one of said plurality of piezo-ceramic tubes forming a first open end of said unit and one end of another one of said plurality of piezo-ceramic tubes forming a second open end of said unit; a solid cap means being secured to the first open end of said unit; a sintered metal cap means having a plurality of pores therein, being secured to the second open end of said unit; a flexible boot for housing said unit, said flexible boot having an open end; means for covering said flexible boot at the open end thereof; a fluid for filling said flexible boot and said unit of said plurality of piezo-ceramic tubes; means for filling said flexible boot and said unit of said plurality of piezo-ceramic tubes with said fluid; and means for extracting voltage signals responsive to an acoustic wave impinging upon said acoustic transducer in the liquid medium.
Claim 3
Dependent Claim
46 words
The acoustic transducer of claim 1 wherein said fluid for filling said boot and said unit of said plurality of piezo-ceramic tubes is an oil having relatively high acoustic compliance for pressure variations due to the acoustic wave impinging on said transducer in the liquid medium.
Claim 4
Dependent Claim
12 words
The acoustic transducer of claim 2 wherein said oil is castor oil.
Claim 5
Dependent Claim
13 words
The acoustic transducer of claim 2 wherein said oil is a silicone oil.
Claim 6
Dependent Claim
34 words
The acoustic transducer of claim 1 wherein said means for extracting voltage signals includes a plurality of electrical leads being connected to said open ends of said unit of said plurality of piezo-ceramic tubes.
Claim 7
Dependent Claim
26 words
The acoustic transducer of claim 1 wherein said plurality of piezo-ceramic tubes includes a pair of generally cylindrical tubes connected in series to a metal block.
Claim 8
Dependent Claim
17 words
The acoustic transducer of claim 6 wherein said sintered cap means includes a plurality of pores therein.
Claim 9
Dependent Claim
24 words
The acoustic transducer of claim 1 wherein said solid cap means includes a plug for filing said flexible boot with said fluid under vacuum.
Claim 10
Dependent Claim
26 words
The acoustic transducer of claim 8 wherein said means for covering said flexible boot includes a plug therein for filling said flexible boot with said fluid.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-10 | 1983-06-11 | 1983-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-10 | 1987-06-11 | 1987-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-10 | 1991-06-11 | 1991-12-11 | $7700.00 | Window Closed / Lapsed |