US3922504A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electroacoustic transducer
Assignee: Foster Electric Co Ltd
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Filing: 1975-01-02
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Granted: 1975-11-25
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Expires: 1995-01-02
Abstract
Abstract An electroacoustic transducer wherein a diaphragm of a nonmagnetic and insulative material having thereon a series of conductors is disposed between a pair of magnetic circuits opposing one another through a slight clearance so that the conductors will lie in magnetic flux flowing between opposite polarity ends of at least a pair of permanent magnets in each magnetic circuit and will move in directions transverse the flux when the diaphragm is vibrated. The magnets in one of the magnetic circuits on sound passing side of the diaphragm are made smaller than those of the other circuit in their size in opposing direction of the respective circuits.
Inventors
- 👤 Kenichiro Kishikawa
- 👤 Yougi Honda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:51
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/02; H04R9/04; H04R9/046; H04R9/047
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
158 words
An electroacoustic transducer comprising a pair of magnetic circuits respectively including at least a pair of permanent magnets and a soft iron plate bridged between opposite polarity ends of said magnets and opposing one another through a clearance so that magnetic flux flowing between the other ends of the magnets will be superposed on another as oriented in the same direction and along said clearance, said soft iron plate in one of said magnetic circuits having perforations for allowing sounds to pass therethrough, and a diaphragm made of a non-magnetic and insulative material and extended within said clearance between the pair of magnetic circuits, said diaphragm having at least on one surface a series of conductors substantially extending in a direction transverse said magnetic flux direction, said permanent magnets in said magnetic circuit of the side having said perforations being smaller than those in the other magnetic circuit in the dimension in opposing direction of the magnetic circuits.
Claim 2
Dependent Claim
158 words
An electroacoustic transducer comprising a pair of magnetic circuits respectively including at least a pair of permanent magnets and a soft iron plate bridged between opposite polarity ends of said magnets and opposing one another through a clearance so that magnetic flux flowing between the other ends of the magnets will be superposed on another as oriented in the same direction and along said clearance, said soft iron plate in one of said magnetic circuits having perforations for allowing sounds to pass therethrough, and a diaphragm made of a non-magnetic and insulative material and extended within said clearance between the pair of magnetic circuits, said diaphragm having at least on one surface a series of conductors substantially extending in a direction transverse said magnetic flux direction, said permanent magnets in said magnetic circuit of the side having said perforations being smaller than those in the other magnetic circuit in the dimension in opposing direction of the magnetic circuits.
Claim 3
Dependent Claim
28 words
The transducer according to claim 1 wherein said permanent magnets having the smaller dimension are of a material which is high in the coercive force and energy product.
Claim 4
Dependent Claim
18 words
The transducer according to claim 2 wherein saiD material for the permanent magnet is rare earth cobalt magnet.
Claim 5
Dependent Claim
15 words
The transducer according to claim 1 wherein said series of conductors is in zigzag shape.
Claim 6
Dependent Claim
32 words
The transducer according to claim 1 wherein said series of conductors is disposed intermediate between the respective permanent magnets of the respective magnetic circuits which are adjacent in the magnetic flux direction.
References Cited (Backward Citations)
US3013905A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |