Patent US4331840A successfully refreshed from Google Patents.
US4331840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electret transducer with tapered acoustic chamber
Assignee: RTI Technologies Pte Ltd
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Filing: 1980-02-22
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Granted: 1982-05-25
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Expires: 2000-02-22
Abstract
Abstract An electret transducer wherein a backplate is mounted between inwardly disposed surfaces of a ridge protruding from a face of a frame, a diaphragm is mounted on the ridge, and an acoustic chamber, which is partially defined by the diaphragm, diminishes in size as it becomes more remote from an opening to it.
Inventors
- 👤 Preston V. Murphy
- 👤 Kurt Hubschi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:06
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/20; H04R1/22; H04R19/00; H04R19/01; H04R19/016; H04R25/00; H04R25/60; H04R25/604
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
136 words
A electret transducer comprising a backplate coated on one face with a dielectric material, a diaphragm spaced apart from and positioned parallel to said backplate and facing said one face, a frame for carrying said backplate and said diaphragm, and means for defining an acoustic chamber, said means including said diaphragm and a member having an inner surface spaced from and opposing said diaphragm, said chamber having an opening thereto located at a chamber boundary non-parallel with said diaphragm and located near one side edge of said diaphragm, the height of said chamber defined by said inner surface and said diaphragm diminshing substantially continuously from near said opening to zero height at an opposite side of said diaphragm, the average width of said inner surface increasing substantially continuously from near said opening to said opposite side.
Claim 2
Dependent Claim
136 words
A electret transducer comprising a backplate coated on one face with a dielectric material, a diaphragm spaced apart from and positioned parallel to said backplate and facing said one face, a frame for carrying said backplate and said diaphragm, and means for defining an acoustic chamber, said means including said diaphragm and a member having an inner surface spaced from and opposing said diaphragm, said chamber having an opening thereto located at a chamber boundary non-parallel with said diaphragm and located near one side edge of said diaphragm, the height of said chamber defined by said inner surface and said diaphragm diminshing substantially continuously from near said opening to zero height at an opposite side of said diaphragm, the average width of said inner surface increasing substantially continuously from near said opening to said opposite side.
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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) | 1985-05-24 | 1985-11-23 | 1986-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-24 | 1989-11-23 | 1990-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-24 | 1993-11-23 | 1994-05-25 | $7700.00 | Window Closed / Lapsed |