Dynamic magnetic information storage or retrieval – Head – Hall effect
Patent
1989-10-05
1991-12-17
Wolff, John H.
Dynamic magnetic information storage or retrieval
Head
Hall effect
360125, G11B 539
Patent
active
050738364
ABSTRACT:
A head structure for reading and writing perpendicular transitions from and to a moving recording medium. The head structure comprises an auxiliary magnetic pole having a tapered edge adjacent its air bearing surface that is oriented transverse to the direction of motion of a recording medium. A magnetoresistive gradiometer employed as the read mechanism is formed within a layer of insulating material disposed on the auxiliary pole member. The gradiometer comprises two magnetoresistive members separated by dielectric material, and two shield members disposed on opposite sides of the magnetoresistive members. The shield members shield the magnetoresistive members from undesired magnetic fields and thus improve the resolution of the signals read from the medium. A coil is formed on and encapsulated within a layer of photoresist material deposited above the layer of insulating material. A primary magnetic pole is disposed on the layer of photoresist material and has a portion thereof which tapers toward the air bearing surface. The primary and auxiliary magnetic poles are adapted to write to the recording medium. A portion of the primary magnetic pole is spaced away from the auxiliary pole member at a location substantially opposite the location of the gradiometer, in order to minimize data erasure in the recording medium by increasing the reluctance of the head strcuture. This gap minimizes data erasure in the recording medium due to stray magnetic fields by enhancing the reluctance of the head structure. A layer of nonmagnetic insulating material is disposed on the primary magnetic pole to encapsulate it and complete the head structure. The geometry of the head structure minimizes its sensitivity to externally applied fields. The magnetoresistive gradiometer is positioned in the gap of the write head so that it experiences minimum fields caused by write coil excitation. Furthermore, the geometry of the gradiometer head shields results in better linear resolution than conventional head designs without shields.
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H. S. Gill et al., Journal of Applied Physics, vol. 65, No. 1, p. 402, Jan. 1989.
Gill Hardayal S.
Hesterman Victor W.
Hewlett--Packard Company
Wolff John H.
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