Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Utility Patent
1999-01-15
2001-01-02
Heinz, A. J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Utility Patent
active
06169645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the class of dynamic magnetic information storage devices, and in particular, to a magneto-resistive head of a hard disk drive.
2. Description of the Related Art
A hard disk drive (HDD) magnetically writes and reads data on and from a rotating disk and is widely used as an auxiliary memory device for computer systems due to the ability of the drive to access a large amount of data at high speed. A magnetic head is generally used to write and read data on and from the disk. The magnetic head has evolved from magnetic inductive heads such as an MIG (Metal In Gap) head of conventional ring type and from thin-film heads to magneto-resistive heads. This development has occurred because the inductive head simultaneously reads and writes with a single gap between two poles and thus has limitations in inductance.
The magneto-resistive head performs write and read operations reliably because it writes data with a conventional inductive head and reads data with a magneto-resistive sensor, independently. The magneto-resistive sensor reads data from a disk using the principle that an electrical characteristic, that is, electrical resistance, varies with changing magnetic properties on the track of the disk.
A conventional magneto-resistive bead has a write pole which includes an upper write pole and a lower write pole, for writing data on a disk. The two write poles are spaced from each other by a predetermined gap. A shield protects a magneto-resistive sensor together with the lower write pole. The magneto-resistive sensor has a magneto-resistive element (MRE) and a soft adjacent layer (SAL), for reading data written on the disk.
The magneto-resistive sensor is disposed along the length of the write gap. The conventional magneto-resistive sensor is positioned with its longer edge orthogonal to the track which is in the direction of movement the magnetic medium, so that the direction of a magnetic flux in the MRE of the magneto-resistive sensor is changed according to variations of a magnetic field vertically generated over a disk and a resistance variation value is read.
However, the conventional magneto-resistive sensor should be made thin enough to render its whole area as a single domain. As a result of this thinness, however, the sensor can fail due to slight external shock such as static discharge, leading to a decrease in product reliability and difficulty in fabrication.
In addition, since the magneto-resistive sensor is oriented orthogonal to the track, it is asymmetrical to the tracks due to variation of resistance in the MRE of the magneto-resistive sensor with the direction of a magnetic flux. The asymmetry to the tracks is due to the distance difference between the write gap and the magneto-resistive sensor, and a skew angle owing to the radial movement of the head. The more distant the head is from a center track, the larger the skew angle becomes. An off-track is generated due to the above skew-angle. Because of the above distance difference and the skew angle, there is a possibility that the magneto-resistive sensor cannot read the signal of the track written by the write gap.
Additional examples of magnetic heads of the conventional art are seen, for example, in the following U.S. Patents. U.S. Pat. No. 4,654,739, to Takahashi et al, entitled
Thin Film Magnetic Head for Reproducing Perpendicular Magnetization
, discloses a thin film magnetic head for reproducing magnetization in which the magnetoresistive element is arranged orthogonally to the travelling direction of the recording medium.
U.S. Pat. No. 4,967,298, to Mowry, entitled
Magnetic Head with Magnetoresistive Sensor, Inductive Write Head, and Shield
, describes an elongated magnetoresistive sensor strip which is longitudinally biased to maintain a single domain sense region. The magnetoresistive strip is oriented perpendicular, that is, orthogonal, to the direction of rotation of the magnetic disk.
U.S. Pat. No. 5,027,243, to Gill et al., entitled
Self-Initialization of Short Magnetosresistive Sensors into a Single Domain State
, describes a dual-element magnetoresistive sensor that uses the longitudinal field produced by the sense-bias currents to initialize the elements into a stable antiparallel state. The device allows a symmetric across-the-track response. This dual-element sensor is apparently designed to be oriented perpendicularly to the track, as col. 3, lines 23-27 of the patent note that the design allows shorter elements which provide the ability to control track width definition and across-the-track pickup. The dual-element design apparently does not serve to provide redundancy in the event of failure of one of the elements.
U.S. Pat. No. 5,406,433, to Smith, entitled
Dual Magnetoresistive Head for Reproducing Very Narrow Track Width Short Wavelength Data
, describes a head with two magnetoresistive elements which are parallel to each other, with the purpose of giving the head “three dimensional” characteristics. The overall orientation of the magnetoresistive elements is perpendicular to the track and the dual-element design apparently does not serve to provide redundancy in the event of failure of one of the elements.
U.S. Pat. No. 5,434,733, to Hesterman et al., entitled
Planar Head Having Separate Read and Write Gaps
, describes a planar silicon magnetoresistive read/write head which is narrower to avoid the recording medium noise at the edges of the track. The planar head oriented parallel to the recording medium is quite different in design from the conventional art discussed earlier.
U.S. Pat. No. 5,654,854, to Mallary, entitled
Longitudinally Biased Magnetoresistive Sensor Having a Concave Shaped Active Region to Reduce Barkhausen Noise By Achieving a Substantially Single Magnetic Domain State
, describes a magnetoresistive sensor constructed with a concave shaped edge in the plane of the element, such that the “stripe height” of the element is at a minimum in the center of the active region and increases toward the off-track boundary. This magnetoresistive sensor is oriented as in the conventional art with its long edge perpendicular to the track.
U.S. Pat. No. 5,703,738, to Kim et al., entitled
Magnetic Head Magneto-Resistive Element with C-shaped Multi-Layered Structure
, describes a thin-film magnetic head with a three-layer structure and an ellipse-like C-shape.
Based on my observation of the art, then, I have found that what is needed is a magnetic head with a magneto-resistive sensor which can be made thin to render its whole area as a single domain but which is robust to static electricity, and which does not suffer from an asymmetric across-the-track response.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved magneto-resistive head for a hard disk drive.
It is a further object of the invention to provide a head in which the magnetoresistive element has a single domain.
It is a yet further object of the invention to provide a head in which the magnetoresistive sensor has a symmetric across-the-track response.
It is a still further object of the invention to provide a head in which the magnetoresistive head is robust to damage caused by static discharge.
It is a yet still further object of the invention to provide a head which has a low failure rate in fabrication.
To achieve the above objects, the present invention provides a magneto-resistive head having a magneto-resistive sensor modified to remove asymmetry to tracks, in a hard disk drive. In the magneto-resistive head, an upper write pole has a write track width, and a lower write pole is positioned under the upper write pole, apart by a predetermined write gap. A magneto-resistive sensor is positioned under the lower write pole, separated by a predetermined gap and orthogonally to the length of the write gap, and has a predetermined read track width, for efficiently reading data from a disk. A shield is positioned under the magneto-resistive sensor, separated by a predetermined gap.
REF
Bushnell , Esq. Robert E.
Heinz A. J.
Samsung Electronics Co,. Ltd.
LandOfFree
Magneto-resistive head having the sensor orthogonally... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magneto-resistive head having the sensor orthogonally..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magneto-resistive head having the sensor orthogonally... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2524067