US3984706A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnetic actuator for voice coil
Assignee: Fujitsu Ltd
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Filing: 1974-11-25
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Granted: 1976-10-05
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Expires: 1994-11-25
Abstract
Abstract An electromagnetic actuator for linear driving of movable heads of a magnetic disc unit in an information processing system. A plurality of slits or plates are provided with a magnetic pole inscribed directly on the internal surface of a permanent magnet, and increase magnetic reluctance of the magnetic path and reduce inductance of a moving coil, thus providing shorter positioning time and stable control. In order to obtain the constant strength of magnetic flux and/or torque of a moving coil, said slits or plates have a particular structure.
Inventors
- 👤 Yuji Inouye
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:24
CPC Classifications
H; H02; H02K; H02K41/00; H02K41/02; H02K41/035; H02K41/0352; H02K41/0354; H02K41/0356; G; G11; G11B; G11B5/00; G11B5/48; G11B5/54; G11B5/55; G11B5/5521; H01; H01F; H01F7/00; H01F7/02; H01F7/0273; H01F7/0289
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
127 words
A voice coil motor having a yoke with a bottom plate, side wall and a center core made of ferromagnetic material, a permanent magnet made of ferrite material magnetized in direction through said side wall and a center core, and inscribed on the internal surface of said yoke, a gap space between said center core and permanent magnet, and a moving coil movably positioned in said gap space, which is characterized in further comprising a magnetic pole inscribed directly on the internal surface of said magnet, said magnetic pole comprising a plurality of magnetically disconnected plates of ferromagnetic material with a center circular hole, the ratio of the thickness of each said plate to the length between said plates is in the range from 0.4 to 1.0.
Claim 2
Dependent Claim
127 words
A voice coil motor having a yoke with a bottom plate, side wall and a center core made of ferromagnetic material, a permanent magnet made of ferrite material magnetized in direction through said side wall and a center core, and inscribed on the internal surface of said yoke, a gap space between said center core and permanent magnet, and a moving coil movably positioned in said gap space, which is characterized in further comprising a magnetic pole inscribed directly on the internal surface of said magnet, said magnetic pole comprising a plurality of magnetically disconnected plates of ferromagnetic material with a center circular hole, the ratio of the thickness of each said plate to the length between said plates is in the range from 0.4 to 1.0.
Claim 3
Dependent Claim
17 words
A voice coil motor according to claim 1, wherein the outward form of said yoke is square.
Claim 4
Dependent Claim
17 words
A voice coil motor according to claim 1, wherein the outward form of said yoke is circular.
Claim 5
Dependent Claim
29 words
A voice coil motor according to claim 1, further comprising a plurality of second plates made of non-magnetic material with a center circular hole placed between said ferromagnetic plates.
Claim 6
Dependent Claim
41 words
A voice coil motor according to claim 1, wherein the width of the gap space at the middle point along the axis of said gap space is larger than that at the end points along said axis of said gap space.
Claim 7
Dependent Claim
136 words
A voice coil motor having a yoke with a bottom plate, side wall and a center core made of ferromagnetic material, a permanent magnet made of ferrite material magnetized in direction through said side wall and a center core, and inscribed on the internal surface of said yoke, a gap space between said center core and permanent magnet, and a moving coil movably positioned in said gap space, which is characterized in further comprising a magnetic pole inscribed directly on the internal surface of said magnet, said magnetic pole comprising a plurality of magnetically disconnected plates of ferromagnetic material with a center circular hole, the width of said gap space at the middle point along the axis of said gap space is larger than that at the end points along said axis of said gap space.
Claim 8
Dependent Claim
136 words
A voice coil motor having a yoke with a bottom plate, side wall and a center core made of ferromagnetic material, a permanent magnet made of ferrite material magnetized in direction through said side wall and a center core, and inscribed on the internal surface of said yoke, a gap space between said center core and permanent magnet, and a moving coil movably positioned in said gap space, which is characterized in further comprising a magnetic pole inscribed directly on the internal surface of said magnet, said magnetic pole comprising a plurality of magnetically disconnected plates of ferromagnetic material with a center circular hole, the width of said gap space at the middle point along the axis of said gap space is larger than that at the end points along said axis of said gap space.
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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) | 1979-10-05 | 1980-04-05 | 1980-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-05 | 1984-04-05 | 1984-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-05 | 1988-04-05 | 1988-10-05 | $7700.00 | Window Closed / Lapsed |