US4145725A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnetic actuator
Assignee: International Business Machines Corp
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Filing: 1977-10-11
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Granted: 1979-03-20
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Expires: 1997-10-11
Abstract
Abstract An actuator comprising a transformer having a fixed primary winding on a magnetic core and a pivotally movable coil linked with the magnetic core and forming a secondary winding of the transformer. A permanent magnet generates a static magnetic field in which the coil is disposed. A transducer arm capable of pivotal movement is attached to the coil. When a current pulse is applied to the primary winding, a current is induced in the coil which reacts with the static magnetic field to cause pivotal movement of the coil and attached arm.
Inventors
- 👤 Christopher N. Wallis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:14
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/54; G11B5/55; G11B5/5521; G11B5/58; G11B5/596; G11B5/59633; G11B5/59655; H; H02; H02K; H02K41/00; H02K41/02; H02K41/035; H02K41/0352; H02K41/0354; H02K41/0358; H02P; H02P25/00; H02P25/02; H02P25/032; H02P25/034
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
100 words
An electromagnetic actuator comprising: a transformer having a fixed primary winding magnetically coupled by a magnetic core to a secondary coil, means for pivotally mounting said coil, means to generate a static magnetic field coupled to said coil, said last mentioned means including a pole gap within which said coil may move, and an actuator arm fixedly attached to said coil and capable of pivotal movement whereby, when a current pulse is applied to said primary winding, a current is induced in said coil which reacts with the static magnetic field causing pivotal movement of said coil and attached arm.
Claim 2
Dependent Claim
100 words
An electromagnetic actuator comprising: a transformer having a fixed primary winding magnetically coupled by a magnetic core to a secondary coil, means for pivotally mounting said coil, means to generate a static magnetic field coupled to said coil, said last mentioned means including a pole gap within which said coil may move, and an actuator arm fixedly attached to said coil and capable of pivotal movement whereby, when a current pulse is applied to said primary winding, a current is induced in said coil which reacts with the static magnetic field causing pivotal movement of said coil and attached arm.
Claim 3
Dependent Claim
25 words
An actuator as set forth in claim 1 in which the axis of rotation of said coil extends through an aperture in said magnetic core.
Claim 4
Dependent Claim
32 words
An actuator as set forth in claim 1 in which said means to generate a static magnetic field comprises a permanent magnet having an arcuate pole gap within said coil may move.
Claim 5
Dependent Claim
30 words
An actuator as set forth in claim 1 in which said magnetic core provides a closed magnetic path which is separate from said means to generate a static magnetic field.
Claim 6
Dependent Claim
18 words
An actuator as set forth in claim 1 in which said coil comprises a single turn formerless armature.
Claim 7
Dependent Claim
21 words
An actuator as set forth in claim 5 in which said armature is a cast structure of a low resistance metal.
Claim 8
Dependent Claim
17 words
An actuator as set forth in claim 5 in which said coil is of substantially rectangular shape.
Claim 9
Dependent Claim
22 words
An actuator as set forth in claim 1 in which said coil and said actuator arm lie substantially in the same plane.
Claim 10
Dependent Claim
24 words
An actuator as set forth in claim 1 in which said actuator arm carries a transducer for reading or writing on a record medium.
Claim 11
Dependent Claim
21 words
An actuator as set forth in claim 1 and including auxiliary means to provide a steady torque on said actuator arm.
Claim 12
Dependent Claim
24 words
An actuator as set forth in claim 10 in which said auxiliary means includes a coil through which a steady current may be passed.
Claim 13
Dependent Claim
40 words
An actuator as set forth in claim 11 further comprising means to supply a current to said primary winding to provide a relatively high initial torque and a current to said auxiliary means to provide a relatively low steady torque.
Claim 14
Dependent Claim
74 words
An actuator as set forth in claim 12 and including a transducer fixed on said actuator arm for traversing and having a magnetic transducing action with respect to a magnetic disk, said means to supply said currents to said primary winding and said auxiliary means being operative to supply such a current to said winding dependent upon the position of the transducer across the disk to allow adequate available flux change for track changing.
References Cited (Backward Citations)
US3849800A
Cited
BE841412R
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-19 | 1982-09-18 | 1983-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-19 | 1986-09-18 | 1987-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-19 | 1990-09-18 | 1991-03-20 | $7700.00 | Window Closed / Lapsed |