Patent US4320263A successfully refreshed from Google Patents.
US4320263A
Expired / Lapsed
US
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Dynamic transducer with moving coil in an air gap filled with magnetic liquid
Assignee: Deutsche Thomson OHG
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Filing: 1980-01-02
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Granted: 1982-03-16
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Expires: 2000-01-02
Abstract
Abstract A dynamic electroacoustic transducer comprising a magnetic pole case defining a magnetic air gap, a coil movably mounted in the air gap and spaced from the magnetic pole case with magnetic liquid extending between the coil and the case in the air gap. A diaphragm is connected to the coil and attached peripherally to the magnetic pole casing so that airtight spaces are defined above and below the coil which are in communication with each other. The airtight sealing of the spaces prevents the liquid portions of the magnetic liquid to evaporate which would result in deterioration of the characteristics of the dynamic electroacoustic transducer.
Inventors
- 👤 Karl-Heinz Thiele
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:49
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/02; H04R9/025; H04R9/027
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
104 words
An electroacoustic transducer comprising, a magnetic pole case defining an air gap, a coil movably mounted in the air gap and spaced from the magnetic pole case, magnetic liquid extending between the coil and the case in the air gap, and a diaphragm connected to the coil and to the case defining with the case a sealed space above and below the magnetic liquid which is gastight, the diaphragm and case defining the sealed spaces being made of material having a pore size substantially less than a mean free path of molecules of magnetic liquid evaporated from the magnetic liquid in said air gap.
Claim 2
Dependent Claim
104 words
An electroacoustic transducer comprising, a magnetic pole case defining an air gap, a coil movably mounted in the air gap and spaced from the magnetic pole case, magnetic liquid extending between the coil and the case in the air gap, and a diaphragm connected to the coil and to the case defining with the case a sealed space above and below the magnetic liquid which is gastight, the diaphragm and case defining the sealed spaces being made of material having a pore size substantially less than a mean free path of molecules of magnetic liquid evaporated from the magnetic liquid in said air gap.
Claim 3
Dependent Claim
29 words
An electroacoustic transducer according to claim 1, wherein said diaphragm comprises a central dome portion and a peripheral portion connected between the dome portion and the magnetic pole case.
Claim 4
Dependent Claim
25 words
An electroacoustic transducer according to claim 2, wherein said dome portion is made of a material chosen from the group consisting of plastic and metal.
Claim 5
Dependent Claim
66 words
An electroacoustic transducer according to claim 1, wherein said diaphragm comprises a central dome portion, a peripheral cone portion connected to said dome portion and extending therefrom and a centering flexible diaphragm connected to said coil and to said magnetic pole case for centering said coil in said air gap, said centering diaphragm defining said airtight space above the magnetic liquid and made of said material.
Claim 6
Dependent Claim
16 words
An electroacoustic transducer according to claim 4, wherein said centering flexible diaphragm is made of rubber.
References Cited (Backward Citations)
DE2716063A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-03-15 | 1985-09-14 | 1986-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-03-15 | 1989-09-14 | 1990-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-03-15 | 1993-09-14 | 1994-03-16 | $7700.00 | Window Closed / Lapsed |