Patent US2177658A successfully refreshed from Google Patents.
US3864751A
Expired / Lapsed
US
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Induced bias magnetoresistive read transducer
Assignee: International Business Machines Corp
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Filing: 1973-10-04
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Granted: 1975-02-04
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Expires: 1993-10-04
Abstract
Abstract A magnetoresistive (MR) read transducer has one MR element and a soft magnetic bias film that is electrically insulated from the MR element. When current is applied to the MR element, the bias film is magnetically saturated, and provides a magnetizing bias field to the MR element. The bias field is independent of the sense current amplitude and of the output signal.
Inventors
- 👤 Thomas Joseph Beaulieu
- 👤 Daniel Andrew Nepela
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:41
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; G11B5/3906; G11B5/3929; G11B5/3932; B; B82; B82Y; B82Y25/00; G01; G01R; G01R33/00; G01R33/02; G01R33/06; G01R33/09; G01R33/093
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
A magnetoresistive read transducer assembly comprising: a magnetoresistive conductive layer formed of magnetic material; a soft highly permeable magnetic bias film disposed substantially parallel to said layer and spaced from said layer but magnetostatically coupled thereto, said layer and film having a prescribed ratio of thicknesses; insulating material disposed between said layer and said bias film; means coupled to said layer for applying a drive current to said layer, so that said bias film is magnetically saturated and produces a back magnetic field that is applied as a linear biasing field to said magnetoresistive element, the magnitude of said biasing field being a function of the magnitude of said drive current.
Claim 2
Dependent Claim
111 words
A magnetoresistive read transducer assembly comprising: a magnetoresistive conductive layer formed of magnetic material; a soft highly permeable magnetic bias film disposed substantially parallel to said layer and spaced from said layer but magnetostatically coupled thereto, said layer and film having a prescribed ratio of thicknesses; insulating material disposed between said layer and said bias film; means coupled to said layer for applying a drive current to said layer, so that said bias film is magnetically saturated and produces a back magnetic field that is applied as a linear biasing field to said magnetoresistive element, the magnitude of said biasing field being a function of the magnitude of said drive current.
Claim 3
Dependent Claim
18 words
A magnetoresistive read transducer assembly as in claim 1, wherein said bias film is thinner than said layer.
Claim 4
Dependent Claim
53 words
A magnetoresistive read transducer assembly as in claim 1, wherein the height of said layer and of said film are substantially the same, and said layer and film are disposed in parallel relationship, so that the easy axes of magnetizatIon for said film and layer are substantially parallel and in the same direction.
Claim 5
Dependent Claim
18 words
A magnetoresistive read transducer assembly as in claim 1, further comprising magnetic shields disposed about said transducer assembly.
Claim 6
Dependent Claim
19 words
A magnetoresistive read transducer assembly as in claim 1, comprising a shunt layer disposed adjacent to said magnetoresistive layer.
Claim 7
Dependent Claim
20 words
A magnetoresistive read transducer assembly as in claim 1, comprising a shunt layer disposed between said layer and said film.
Claim 8
Dependent Claim
22 words
A magnetoresistive read transducer assembly as in claim 1, wherein said magneto-resistive layer has a thickness in the range of 200-500 Angstroms.
Claim 9
Dependent Claim
25 words
A magnetoresistive read transducer assembly as in claim 1, wherein said bias film is made of a similar material as that used for said layer.
Claim 10
Dependent Claim
14 words
A magnetoresistive read transducer assembly as in claim 8, wherein said material is Permalloy.
Claim 11
Dependent Claim
21 words
A magnetoresistive read transducer assembly as in claim 1, wherein said bias film is made of a magnetically soft ferrite material.
Claim 12
Dependent Claim
28 words
A magnetoresistive read transducer assembly as in claim 1, including means for applying a magnitude of current to said layer in the range of 5 to 30 milliamperes.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |