Dynamically programmable magneto-resistive head write and read b

Details Dynamically programmable magneto-resistive head write and read b Dynamically programmable magneto-resistive head write and read b

1997-06-04

2000-09-19

Hindi, Nabil

Dynamic magnetic information storage or retrieval

General recording or reproducing

Specifics of biasing or erasing

360 46, 360 67, G11B 503, G11B 509, G11B 502

Patent

active

061221279

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates generally to the field of disc drive data storage devices, and more particularly, but not by way of limitation, to an apparatus and method for dynamically programming write and read bias currents in a disc drive magneto-resistive head.


BACKGROUND ART

Modern hard disc drives comprise one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks by an array of transducers ("heads") mounted to a radial actuator for movement of the heads relative to the discs.
Typically, such radial actuators employ a voice coil motor to position the heads with respect to the disc surfaces. The heads are mounted via flexures at the ends of a plurality of arms which project radially outward from a substantially cylindrical actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the heads move in a plane parallel with the surfaces of the discs.
The actuator voice coil motor includes a coil mounted on the side of the actuator body opposite the head arms so as to be immersed in the magnetic field of an array of permanent magnets. When controlled DC current is passed through the coil, an electromagnetic field is set up which interacts with the magnetic field of the permanent magnets and causes the coil to move relative to the permanent magnets in accordance with the well-known Lorentz relationship. As the coil moves relative to the permanent magnets, the actuator body pivots about the pivot shaft and the heads are moved across the disc surfaces.
Typically, the heads are supported over the discs by actuator slider assemblies which include air-bearing surfaces designed to interact with a thin layer of moving air generated by the rotation of the discs, so that the heads are said to "fly" over the disc surfaces. Generally, the heads write data to a selected data track on the disc surface by selectively magnetizing portions of the data track through the application of a time-varying write current to the head. In order to subsequently read back the data stored on the data track, the head detects flux transitions in the magnetic fields of the data track and converts these to a signal which is decoded by read channel circuitry of the disc drive.
Of the variety of head constructions presently used in modern disc drives, magneto-resistive heads (hereinafter "MR heads") are of particular interest. MR heads include the use of a thin film element which has the characteristic of having a changed dc resistance in the presence of a magnetic field of a predetermined orientation. Taking advantage of this characteristic, MR heads generally perform a read operation by passing a bias current through this thin film element and detecting changes in this bias current as a result of exposure of the thin film element to the flux transitions from the data track (as the resistance of the thin film element is changed thereby). These changes in the, bias current are subsequently decoded by the read channel in order to reconstruct the data that was previously stored on the track. Generally, the MR heads write data to the track using an inductive writing technique, whereby a write current of a selected magnitude and polarity is passed through the head in order to selectively magnetize portions of the data track.
Typically, MR heads have two pairs of electrical connections, one pair for the write element portion of the head and one pair for the read element portion of the head, with each pair of connections comprising a current source and a current return path. Thus, during a read operation, one pair of the connections is used to pass the read bias current through the thin film element of the MR head and time-varying changes in the read bias current are detected by AC s

REFERENCES:
patent: 4799112 (1989-01-01), Bremmer et al.
patent: 5107378 (1992-04-01), Cronch et al.
patent: 5132852 (1992-07-01), Price, Jr.
patent: 5262907 (1993-11-01), Duffy et al.
patent: 5270882 (1993-12-01), Jove et al.
patent: 5367411 (1994-11-01), Nishiyama et al.
patent: 5600500 (1997-02-01), Madsen et al.
patent: 5719719 (1998-02-01), Tsuyoshi et al.
patent: 5726821 (1998-03-01), Cloke et al.
[Author] anonymous; Preamplifier for Magnetoresistive Heads Using Series Voltage Bias, IBM Technical Disclosure Bulletin, Jan. 1989, pp. 383-384, vol. 31, No. 8, New York, US.

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