US4903158A
Expired / Lapsed
US
⏱️ 0.0 years remaining
MR head with complementary easy axis permanent magnet
Assignee: Eastman Kodak Co
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Filing: 1988-07-28
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Granted: 1990-02-20
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Expires: 2008-07-28
Abstract
Abstract The invention teaches the use of a permanent magnet easy axis biasing structure having the same (or nearly so) physical geometry as the MR sense film itself, whereby a similar, but opposite, demagnetization field is generated in the biasing structure as is generated in the sense film. Thus, with the two demagnetization fields complementarily cancelling each other, any tendency of the sense film for multi-domain formation therein is cancelled (or at least lessened).
Inventors
- 👤 Neil Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:16
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; G11B5/3906; G11B5/3929; G11B5/3935; G11B5/3938; G11B5/399
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
148 words
A magnetoresistive head for use in the playback of magnetically recorded signals comprising a. a magnetoresistive sense film having a given geometric configuration, b. means for supporting said magnetoresistive sense film, c. said magnetoresistive sense film having a longitudinal magnetization component which results in a demagnetization field in said magnetoresistive sense film. d. means for conveying a sense current from one portion of said magnetoresistive sense film to another thereof, e. permanent magnet means having essentially the same geometric configuration as said magnetoresistive sense film, and f. means for so electrically insulating said permanent magnet means from said sense film that said permanent magnet means substantially overlays said magnetoresistive sense film wherein the magnetic field of said permanent magnet means is so coupled to said magnetoresistive sense film to substantially cancel said demagnetization field in said magnetoresistive sense film, thereby to reduce Barkhausen effects in said magnetoresistive head.
Claim 2
Dependent Claim
148 words
A magnetoresistive head for use in the playback of magnetically recorded signals comprising a. a magnetoresistive sense film having a given geometric configuration, b. means for supporting said magnetoresistive sense film, c. said magnetoresistive sense film having a longitudinal magnetization component which results in a demagnetization field in said magnetoresistive sense film. d. means for conveying a sense current from one portion of said magnetoresistive sense film to another thereof, e. permanent magnet means having essentially the same geometric configuration as said magnetoresistive sense film, and f. means for so electrically insulating said permanent magnet means from said sense film that said permanent magnet means substantially overlays said magnetoresistive sense film wherein the magnetic field of said permanent magnet means is so coupled to said magnetoresistive sense film to substantially cancel said demagnetization field in said magnetoresistive sense film, thereby to reduce Barkhausen effects in said magnetoresistive head.
Claim 3
Dependent Claim
32 words
The magnetoresistive head of claim 1 wherein said permanent magnet means is a coating of magnetically hard material that is magnetized in the direction of the length of said magnetoresistive sense film.
Claim 4
Dependent Claim
22 words
The magnetoresistive head of claim 2 wherein the coating of said permanent magnet means is a coating of approximately 1000 Å thick.
Claim 5
Dependent Claim
41 words
The magnetoresistive head of claim 2 further comprising a. a magnetically soft layer, and b. means for so electrically insulating said layer from said magnetoresistive sense film that current through said magnetoresistive sense film biases the moment of said sense film.
Claim 6
Dependent Claim
107 words
In a magnetoresistive head of the type having a. support means b. a thin film magnetoresistive element having a demagnetization field associated therewith, said magnetoresistive element supported by said support means and having a given geometric configuration, the improvement comprising a. non-magnetic means supported by said thin film magnetoresistive element, and b. permanent magnet means supported by said non-magnetic means, said permanent magnet means having essentially the same general configuration as said magnetoresistive element and further having the direction of its magnetic field at said magnetoresistive element opposed in direction to said demagnetization field, said permanent magnet means being in essentially perfect registry with said magnetoresistive element.
Claim 7
Dependent Claim
107 words
In a magnetoresistive head of the type having a. support means b. a thin film magnetoresistive element having a demagnetization field associated therewith, said magnetoresistive element supported by said support means and having a given geometric configuration, the improvement comprising a. non-magnetic means supported by said thin film magnetoresistive element, and b. permanent magnet means supported by said non-magnetic means, said permanent magnet means having essentially the same general configuration as said magnetoresistive element and further having the direction of its magnetic field at said magnetoresistive element opposed in direction to said demagnetization field, said permanent magnet means being in essentially perfect registry with said magnetoresistive element.
Claim 8
Dependent Claim
21 words
The improved magnetoresistive head of claim 5 wherein a. said magnetoresistive element and b. said permanent magnet means are elongated structures.
Claim 9
Dependent Claim
38 words
The improved magnetoresistive head of claim 6 wherein said permanent magnet means is a deposition of magnetically hard material, on said non-magnetic means, that has been magnetized in the direction of the length of said permanent magnet means.
Claim 10
Dependent Claim
23 words
The improved magnetoresistive head of claim 7 wherein said deposition of magnetically hard material has a thickness that is less than 1000 Å.
References Cited (Backward Citations)
US3881190A
Cited
US4052748A
Cited
US4142218A
Cited
US4122505A
Cited
US4103315A
Cited
US4489484A
Cited
US4195323A
Cited
US4321641A
Cited
US4141051A
Cited
US4191977A
Cited
US4556925A
Cited
US4660113A
Cited
JPS58220241A
Cited
US4547824A
Cited
US4580175A
Cited
US4535375A
Cited
JPS60157712A
Cited
US4623867A
Cited
JPS61134913A
Cited
US4755897A
Cited
US4809109A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-19 | 1993-08-21 | 1994-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-19 | 1997-08-21 | 1998-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-19 | 2001-08-21 | 2002-02-20 | $7700.00 | Window Closed / Lapsed |