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US 4,388,662 AGranted
Thin film magnetoresistive head
AssigneeEastman Kodak Company
InventorsFrederick Jeffers, Richard J. McClure
Life of this patent
Estimating the term…
Abstract
A flux-responsive magnetic head having a transducer gap also has first and second back gaps across which, respectively, are first and second thin film magnetoresistive elements. The elements have similarly oriented magnetization vectors and, as such, the magnetoresistive elements are differentially responsive to flux entering said transducer gap. Spurious fields, however, have no differential effect on the resistances of the magnetoresistive elements. In a preferred form of the invention, an additional, similar working, pair of magnetoresistive elements is employed across the back gaps, such additional elements not only providing increased signal response, but also serving as keepers for the first pair of magnetoresistive elements.
Claims9
A magnetic head comprising
- (a) first and second magnetic pole parts disposed to define a transducer gap therebetween,
- (b) magnetic means positioned relative to said first and second pole parts and respectively forming therewith first and second high reluctance gaps therebetween,
- (c) a first thin film magnetoresistive element magnetically coupling said magnetic means to said first pole part at said first gap, said first magnetoresistive element having a magnetization vector that is in the plane of its thin film, and
- (d) a second thin film magnetoresistive element magnetically coupling said magnetic means to said second pole part at said second gap, said second magnetoresistive element having a magnetization vector that is in the plane of its thin film, the quiescent orientation of said second element magnetization vector being in substantially the same direction as the quiescent direction of the magnetization vector of said first element,
- whereby magnetic flux entering said transducer gap causes a differential change in the electrical resistances of said first and second magnetoresistive elements, but spurious magnetic fields to which said head is exposed causes similar changes to the resistances of said first and second magnetoresistive elements.
2 more elements
Magnetic head apparatus comprising
- (a) first, second and third magnetic means forming (1) a first high reluctance transducer gap between said first and second means, (2) a first high reluctance back gap between said first and third means, and (3) a second high reluctance back gap between said second and third means,
- (b) a first thin film magnetoresistive element magnetically coupling said first and third means across said first back gap,
- (c) a second thin film magnetoresistive element magnetically coupling said second and third means across said second back gap,
- the quiescent magnetization vectors of said first and second thin film magnetoresistive elements being so similarly oriented that magnetic flux entering said transducer gap causes a differential change in the resistances of said first and second magnetoresistive elements, and spurious magnetic fields which envelop the head apparatus cause like changes to the resistances of said magnetoresistive elements.
1 more element
A magnetoresistive head that is substantially immune to spurious magnetic fields comprising
- (a) first and second pole parts disposed to define a transducer gap therebetween,
- (b) magnetic means disposed in relation to said pole parts and forming therewith first and second high reluctance back gaps, respectively, between said magnetic means and said first and second pole parts, each said back gap having first and second opposing sides thereof,
- (c) a first thin film magnetoresistive element magnetically coupling said first pole part to said magnetic means across said first side of said first back gap,
- (d) a second thin film magnetoresistive element magnetically coupling said second pole part to said magnetic means across said first side of said second back gap,
- the quiescent magnetization vectors of said first and second magnetoresistive elements being similarly oriented in a first direction
- (e) a third thin film magnetoresistive element magnetically coupling said first pole part to said magnetic means across said second side of said first back gap and
- (f) a fourth thin film magnetoresistive element magnetically coupling said second pole part to said magnetic means across said second side of said second back gap,
- the quiescent magnetization vectors of said third and fourth magnetoresistive elements being similarly oriented in a second direction that is substantially opposite said first direction,
- whereby (1) signal flux entering said transducer gap causes the resistances of said first and second magnetoresistive elements and the resistances of said third and fourth magnetoresistive elements to change differentially, but spurious fields applied to said head cause like changes to the resistances of said first and second magnetoresistive elements and like changes to the resistances of said third and fourth magnetoresistive elements, and (2) said first and third magnetoresistive elements act as keepers for each other, and said second and fourth magnetoresistive elements act as keepers for each other.
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Magnetic head apparatus that has both good output in response to signal flux and substantial immunity to spurious fields comprising
- (a) first and second magnetic pole parts disposed to define a transducer gap adapted to receive magnetic signal flux,
- (b) a magnetic back bar bridging said pole parts and forming therebetween first and second high reluctance back gaps, each said back gap having first and second opposing sides, and
- (c) first, second, third and fourth thin film magnetoresistive elements,
- the first magnetoresistive element bridging the first side of the first back gap,
- the second magnetoresistive element bridging the first side of said second back gap,
- the third magnetoresistive element bridging the second side of the first back gap and
- the fourth magnetoresistive element bridging the second side of the second back gap,
- the quiescent magnetization vectors of said first and second magnetoresistive elements being similarly oriented in a first direction, and
- the quiescent magnetization vectors of said third and fourth magnetoresistive elements being similarly oriented in a second direction that is substantially opposite said first direction.
6 more elements
Dependencies are inferred from the claim text.