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Patent US3665352A successfully refreshed from Google Patents.
US3665352A
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Permanent magnet system for a loudspeaker
Assignee: Deutsche Edelstahlwerke AG
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Filing: 1970-05-12
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Granted: 1972-05-23
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Expires: 1990-05-12
Abstract
Abstract A permanent magnet system is made for a loudspeaker consisting of a rod or ring-formed axial magnetic magnets and soft iron parts. A portion of the ferromagnetic circuit in the system is made from a mechanically machinable, dense alloyed ferritic steel with higher electrical and lower magnetic resistance than soft iron and a saturation magnetism at least equal to the air gap induction required by the system.
Inventors
- 👤 Hermann Dietrich
- 👤 Karl Schuler
- 👤 Heinz Gunter Meese
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:00
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/02; H04R9/025; H01; H01F; H01F7/00; H01F7/02; H01F7/0273; H01F7/0289; H04R2209/00; H04R2209/022
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
69 words
In a permanent magnet system for a loudspeaker which consists of axial magnetic magnets and sofT iron parts forming an air gap therebetween the improvement comprising making a portion of the ferromagnetic circuit in the system from a mechanically machinable, dense, alloyed ferritic steel with higher electrical and lower magnetic resistance than soft iron and a saturation magnetization at least equal to the airgap induction required by the system.
Claim 2
Dependent Claim
69 words
In a permanent magnet system for a loudspeaker which consists of axial magnetic magnets and sofT iron parts forming an air gap therebetween the improvement comprising making a portion of the ferromagnetic circuit in the system from a mechanically machinable, dense, alloyed ferritic steel with higher electrical and lower magnetic resistance than soft iron and a saturation magnetization at least equal to the airgap induction required by the system.
Claim 3
Dependent Claim
30 words
A permanent magnet system according to claim 1 wherein the portion of the ferromagnetic circuit of the system in the region of the air gap consists of alloyed ferritic steel.
Claim 4
Dependent Claim
49 words
A permanent magnet according to claim 2 wherein the soft iron part is located concentric with respect to the magnets including first and second plates for the system which are attached to the longitudinal ends of the magnets and soft iron part, said plates being made of ferritic steel.
Claim 5
Dependent Claim
39 words
A permanent magnet according to claim 1 wherein a portion of the ferromagnetic circuit in the system consists of up to 0.15% C., 0.3 to 2.5% of Si, 0.2 to 2.0% Al, 5 to 25% Cr and balance iron.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |