US4256986A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic pickup subassembly
Assignee: 3M Co
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Filing: 1979-04-16
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Granted: 1981-03-17
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Expires: 1999-04-16
Abstract
Abstract Magnetic pickup having a matrix-bonded permanent magnet sleeve around one end of an elongated cylindrical pole piece and a coil around the other end. The magnet sleeve has a preferred direction of magnetization radial to the axis of the pole piece.
Inventors
- 👤 Glenn R. Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:47
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/488
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
100 words
Subassembly of a magnetic pickup, said subassembly comprising an elongated ferromagnetic pole piece which is substantially symmetrical about an axis, a matrix-bonded permanent magnet sleeve which fits closely around the pole piece and is substantially coterminous with one end of the pole piece while not substantially extending beyond the other end of the pole piece, the magnet sleeve having preferred directions of magnetization radial to said axis and there being no ferromagnetic path directly between the inner and outer surfaces of the sleeve, said subassembly being formed to receive an electrical coil around said other end of the pole piece.
Claim 2
Dependent Claim
100 words
Subassembly of a magnetic pickup, said subassembly comprising an elongated ferromagnetic pole piece which is substantially symmetrical about an axis, a matrix-bonded permanent magnet sleeve which fits closely around the pole piece and is substantially coterminous with one end of the pole piece while not substantially extending beyond the other end of the pole piece, the magnet sleeve having preferred directions of magnetization radial to said axis and there being no ferromagnetic path directly between the inner and outer surfaces of the sleeve, said subassembly being formed to receive an electrical coil around said other end of the pole piece.
Claim 3
Dependent Claim
18 words
Subassembly as defined in claim 1 wherein the matrix-bonded magnet sleeve comprises barium, strontium and/or lead ferrite particles.
Claim 4
Dependent Claim
19 words
Subassembly as defined in claims 1 or 2 wherein the matrix-bonded magnet sleeve comprises stabilized rare-earth-based permanent magnet particles.
Claim 5
Dependent Claim
15 words
Subassembly as defined in claim 1 wherein the magnet sleeve is formed with screw threads.
Claim 6
Dependent Claim
39 words
Subassembly as defined in claim 1 wherein the magnet sleeve is substantially coterminous with said other end of the pole piece and is formed adjacent said other end in the shape of a bobbin for winding an electrical coil.
Claim 7
Dependent Claim
18 words
Subassembly as defined in claim 1 wherein the magnet sleeve is magnetized in directions radial to said axis.
Claim 8
Dependent Claim
22 words
A magnetic pickup comprising a subassembly as defined in claim 1 and a coil around said other end of the pole piece.
Claim 9
Dependent Claim
21 words
A magnetic pickup as defined in claim 7 wherein the magnet sleeve is coterminous with both ends of the pole piece.
Claim 10
Dependent Claim
39 words
A magnetic pickup as defined in claim 8 wherein the coil is encapsulated by the magnet sleeve and the leads from the coil emerge from the end of the magnet sleeve adjacent said one end of the pole piece.
Claim 11
Dependent Claim
22 words
A magnetic pickup as defined in claim 9 and encapsulated with electrically insulating resin which also encapsulates the leads adjacent the coil.
Claim 12
Dependent Claim
23 words
A magnetic pickup as defined in claim 7 wherein the coil does not extend radially outwardly beyond the face of the magnet sleeve.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |