US 5,644,456 AGranted

Magnetically capped dual magnetoresistive reproduce head

AssigneeEastman Kodak Company

InventorsNeil Smith, Jay D. Freeman

Life of this patent

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Abstract

A magnetically permeable "cap" is deposited across the top face (the bottom face being the face at the head-medium interface), or on the end faces, or on both the top and the end faces of a DMR reproduce head. The top cap serves as a magnetic keeper which provides flux closure between the two MR elements of the DMR when they are transversely magnetized anti-parallel to each other. By means of a magnetic cap of only moderate effective permeability, the current density required to optimally bias a DMR head is reduced by a factor of from 3 to 4. The presence of the top cap layer also provides an increase in the intrinsic sensitivity (independent of the bias level) of the DMR by a factor of 2. Further, when the head is fully biased to also include longitudinal biasing of the MR elements, the caps at the longitudinal ends of the MR stripes magnetically stabilize the fully antisymmetric bias configuration providing optimal performance for a DMR head. The end caps also provide for establishing the necessary electrical conductive path between the two MR elements of the DMR. In an additional embodiment, an electrically insulating layer between the magnetically permeable layer and the MR elements breaks any exchange coupling between the magnetically permeable layer and the MR elements.

Claims7

Dependent claims

A magnetic head assembly for detecting magnetically recorded signals from a magnetic medium comprising:

first and second rectangular thin film magnetoresistive elements, each of which has a long dimension with first and second long sides and a short dimension with first and second short ends connecting said long sides;
a spacer between said first and second magnetoresistive elements;
shorting means for electrically shorting said first ends and said second ends, respectively, of said first and second magnetoresistive elements;
current means connected to said shorting means for flowing a sense current through said first and second magnetoresistive elements between said first and second shorted ends, said sense current flow mutually magnetically self-biasing said first and second magnetoresistive elements anti-symmetric to one another along said long dimension;
a cap of magnetic permeable material extending along said long dimension of said elements, covering said elements and said spacer, along said first long sides of said elements;
and
means for orienting said magnetic head assembly relative to said magnetic medium so that said second long sides of said elements face said medium and so that magnetic fields from magnetically recorded signals on said medium are directed along the short dimension of said elements such that magnetic flux follows a path in one direction along the short dimension of said first element, is shorted through said cap, and follows a path along the short dimension of said second element in a direction opposite to said one direction.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/583,578Filed 5 Jan 1996 · continuation
Priority: 12 Jan 1994
Granted: 1 Jul 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G11B 5/3938
Flux closure films not being part of the track flux guides: the flux closure films being used for absorbing or reducing demagnetisating or…
G11B 5/3948
Heads comprising more than one sensitive element: the sensitive elements being active read-out elements
G11B 5/3954
The active elements being arranged on several parallel planes: the active elements transducing on a single track
G11B 5/3987
Specially shaped layers: with provision for closing the magnetic flux during operation