International Business Machines Corporation

Headway Technologies, Incorporated

Hung Liang Hu

Yaw Shing Tang

Lijie Guan

Kochan Ju

David Malcolm Hannon

Laurence Lee Rosier

Ching Hwa Tsang

Klaas Berend Klaassen

Jacobus C Van Peppen

Walter Eugene Weresin

Byron R Brown

Liji Guan

William Albert Reynolds, Jr

Joseph J Lum

Prior art designs of single pole writers have been limited by premature saturation at the tip. This limits the head field that can be achieved without simultaneously widening the write profile. This problem has bee solved by means of a vertical main pole whose thickness has its conventional value a short distance from the tip but that tapers down to a significantly reduced value as it approaches the tip. A process for manufacturing this tapered tip design is also presented.

Process to manufacture a magnetic write head

The traditional single pole perpendicular writer has two major problems&#x2014;insufficient field gradient in the down track direction and adjacent track erasure (ATE) caused by side fringing fields. These problems have been overcome by tapering the main pole and then shielding it on all four sides.

Four sided shield structure for a perpendicular write head

Perpendicular write head with tapered main pole

Prior art designs of single pole writers have been limited by premature saturation at the tip. This limits the head field that can be achieved without simultaneously widening the write profile. This problem has been solved by means of a vertical main pole whose thickness has its conventional value a short distance from the tip but that tapers down to a significantly reduced value as it approaches the tip. A process for manufacturing this tapered tip design is also presented.

A process for reducing fringe field effects of a main write pole by shielding it on all four sides, with the regular return pole also serving as the leading edge shield, is described. The main pole may also be tapered and the leading edge and side shields may be magnetically connected to each other.

Process of manufacturing a four-sided shield structure for a perpendicular write head

In a single vertical pole magnetic writer, flux passing through the return pole can sometimes be strong enough to erase previously recorded data. This problem has been overcome by the addition of a second return pole that is magnetically connected to the conventional return pole for the purpose of collecting leaked flux, thereby preventing it from reaching the underlayer.

Return pole field reduction for perpendicular write head

Conventional perpendicular writers that utilize an extended return pole are subject to large undershoot fields. This problem has been reduced by replacing the prior art extended return pole by one whose magnetic potential has been increased relative to both the main and return poles. In a first embodiment, a second non-magnetic gap is inserted between the extended return pole and the return pole. In a second embodiment, the extended return pole is made very thin, thereby increasing its reluctance, while a third embodiment combines both reluctance-increasing features in a single design.

Perpendicular magnetic writer with magnetic potential control shield

Conventional perpendicular writers that utilize an extended return pole are subject to large flux leakage. This problem has been reduced in the prior art by adding a downstream shield. This still leaves significant upstream leakage. This has now been eliminated by adding an upstream shield and then connecting the up and downstream shields by using side shields. The latter need not extend all the way from the downstream to the upstream shield in which case their thickness is increased relative to the full side shields.

Fully shielded perpendicular recoding writer

A rotary actuator disk drive uses substantially identical dual-element inductive write/magnetoresistive read transducers for both the top and bottom disk surfaces. There is no requirement that the read elements be mechanically offset from the write elements, as is typically the case in rotary actuator disk drives due to the head-to-track skew caused by the inherent nonlinear path of the heads across the data tracks. The transducers are supported on the trailing ends of the head carriers in such a manner that the geometric centers of the read and write elements are aligned without any mechanical offset. Sense currents of opposite polarity are provided to the magnetoresisitve read elements adjacent the top and bottom disk surfaces to shift the magnetic centers of the top and bottom read elements in opposite directions relative to their geometric centers. The amount and direction of the magnetic shift is such that the read elements are effectively offset from their respective write elements so that the skew caused by the rotary actuator has minimal effect on alignment of the read and write elements with the data tracks.

Rotary actuator disk drive with identical dual-element read/write

A method and apparatus for measuring the flying height of a slider supporting a magnetic transducer in-situ in a direct manner in an operational magnetic disk storage system. The method and apparatus produce relative motion between the magnetic transducer and a magnetic recording medium at a first velocity so that the resulting air bearing positions the magnetic transducer slider at a first flying height from the magnetic medium. A single signal of constant periodicity is written over a predetermined area of the recording medium by the magnetic transducer, and a readback signal is sensed from the predetermined area of the recording medium to produce a first signal. The flying height of the magnetic transducer slider is lowered to substantially zero, and a readback signal is sensed at the lowered flying height to produce a second signal. The first flying height is then calculated as the ratio, expressed in decibels, of the first and second signals times the wavelength divided by a constant. In an alternate embodiment a plurality of signals are recorded and readback signals are simultaneously sensed at two separate wavelengths. In a further embodiment, a signal is recorded which has a spectral content comprising a plurality of different frequencies, and readback signals are simultaneously sensed at two separate wavelengths.

Method and apparatus for in-situ measurement of head/recording medium

A propagation track for use in contiguous disk bubble devices consists of a plurality of spaced dovetail shaped elements which are connected at one end thereof by a track portion which faces in the direction of and is substantially perpendicular to the (1,1,2) axis. The first, third and fifth sides of the dovetail structure are elongated and also face in the direction of and are substantially perpendicular to the (1,1,2) axis. The remaining sides of the dovetail structure have different orientations, the second side facing in the direction of and being substantially perpendicular to the (2,1,1) axis, and the fourth side facing in the direction of and being substantially perpendicular to the (1,2,1) axis. The orientation of the two cusps formed by the first and second sides and the fourth and fifth sides is such that the lines bisecting and pointing toward the cusps are substantially parallel to the (1,2,1) and (2,1,1) axes, respectively.

Dovetail propagation structure for contiguous disk bubble devices

A propagation pattern for contiguous disk bubble devices consists of a plurality of parallel propagation tracks in which each propagation track is asymmetric. Adjacent propagation tracks are positioned so that the cusps that face each other are aligned therewith. The region between adjacent tracks forms two subregions which are mirror images of each other when the region is bisected by a longitudinal midplane.

Asymmetric sawtooth contiguous disk propagation pattern

A device adapted for biasing bubble domains in a low externally applied magnetic bias field. This device is suitable for use when isolated bubbles or a column of bubbles are translated to or from a bubble lattice. The device has a pair of parallel channels, each containing a stripe domain therein. Positioned between the pair of channels is a channel for the translation of isolated bubbles. Positioned in juxtaposition with the bubble containing channel and the pair of stripe containing channels are a pair of parallel conductors. The passage of current through one conductor in one direction and a current through the other conductor in the opposite direction together with the presence of the stripe domains in the two channels provide a biasing field around the channel containing the bubbles which permits the isolated bubble operating margin to overlap the lattice operating margin.

Device for biasing bubble domains

A device adapted for use in a low externally applied magnetic field, for example, 15 Oe, with a bubble lattice system is described. The device has a Y shaped channel in which bubbles are propagated between a bubble lattice column and either detector means or generator means. The magnetic pattern surrounding the Y shaped channel is controlled to yield a self biasing magnetic field which enables the device to retain the advantages of the close bubble packing in a bubble lattice for the detection and generation operations.

Bubble lattice device

A system suitable to transfer a bubble domain from one field to a second field where the field is the largest area formed by exposing a pattern and which all of the dimensions are critical is disclosed. A magnetic domain is propagated out of the first field through an outlet into an inlet of the second field. In a preferred embodiment, the width of the outlet is one to ten bubble diameters and the width of the inlet opening is two to ten bubble diameters, the inlet opening being always at least as wide as the outlet opening. Associated with the inlet opening is a contracting means, for example, a Chevron pattern of decreasing height, which reduces the size of the domain to a size suitable for use in the bubble system in the second magnetic field.

Growing community of inventors

Los Altos Hills, CA, United States of America

Hung Liang Hu