International Business Machines Corporation

Vincent N Kahwaty

Joseph Adam Aboaf

Edward V Denison

Gerald Steving

Jules David Friedman

Donald Clifford Hofer

Robert P Zammit

Gustave Christian Stern

Carl R Valentino

Herman Carl Kluge, Ii

Edward Virgil Dennison

James Lamar Nix

Frank B Shelledy

Glen P Double

George Frederick Adams

James D Randall

Fritz M Reinhart

Herman C Kluge

Joseph M Schmalhorst

Antonio Rubio

A multi-element read-write magnetic recording head for recording information on a magnetic tape and for reading recorded information therefrom is provided. The recording head comprises an equal number of associated read elements and write elements to form a two-gap recording head comprising pairs of read and write elements. The two-gap recording head further comprises a first module and a second module, the first and second modules each comprising a plurality of read and write head elements. A first group of read and write heads is configured to perform in a forward direction of movement of the magnetic tape and a second group of read and write heads is configured to perform in a reverse direction of movement of the magnetic tape. One of the modules contains an equal number of forward read heads and reverse write heads and the other of the modules contains an equal number of reverse read heads and forward write heads, to provide decoupling of reading and writing functions and to enable servoing by a given read element of a write element associated therewith. Asymmetry of the magnetic recording head is provided by offsetting leads to the read elements in a given module from leads to said write elements in the same module, while maintaining orthogonality between read and write element leads near the read and write elements. The asymmetry minimizes both inductive and capacitive feedthrough into adjacent readers. As a consequence, noise produced during the writing process is reduced, providing an improved signal-to-noise ratio and thereby permitting same gap servoing.

Asymmetric recording head for same gap servo optimization

A magneto-resistive read/write tape head is provided for reading and writing to tape media along a tape head face. The tape head comprises a plurality of modules, each module comprising a read element and a write element spaced apart and terminating at the tape head face and formed over a substrate. The read element comprises a soft film bias layer and a hard film bias layer butted against the SFB layer. The write element comprises two pole tips spaced apart by a gap. The tape head further includes a plurality of activating conducting coil turns operatively associated with the write element and covered by a cross-linked photoresist and positioned between the gap and one of the pole tips and set back from the tape head face. The tape head has at least one of the following elements: (a) a wear shield between the read element and the write element for limiting wear of the gap between the two pole tips, the wear shield being grounded for decoupling read and write functions of the tape head, for allowing same module read/servo/write functions simultaneously, and for grounding static charge from the tape media; (b) a layer of electrically conductive and corrosion-resis tant material, such as rhodium, under the hard film bias layer to reduce its resistance; and (c) a non-activating dummy coil turn closer to the pole tips than the activating coil turns for defining a forward termination of the cross-linked photoresist between the activating coil turns and the tape head face to thereby provide improved ease of processability.

Piggyback magneto-resistive read/write tape head with optimized process

A magnetoresistive sensor design and fabrication process that provides improved microtrack profile linearity for servo elements while simultaneously providing stable and linear data sensing elements suitable for high density tape head applications. The stability and uniformity of both data and servo sensor elements is enhanced through the use of a grating profile under both the soft film biased magnetoresistive sensor layer and the hard bias stabilizing magnets. Processing steps are eliminated by replicating the grating pattern for the servo sensor elements through a thick layer of alumina or silicon dioxide. The outer read shield is removed from the servo elements using a stripping process that eliminates structural damage arising from alumina pinhole's. Both element types are free of significant Barkhausen noise and instability because of the grating-stabilized domains in both the active magnetoresistive regions and the passive hard-biasing regions of each sensor. Each servo sensor is disposed at a greater distance from the single shield to optimize the microtrack profile. The resulting reduction in servo sensor frequency response leaves sufficient bandwidth for precise servo positioning.

Method of making magnetoresistive sensor with improved microtrack

A magnetoresistive sensor design and fabrication process that provides improved microtrack profile linearity for servo elements while simultaneously providing stable and linear data sensing elements suitable for high density tape head applications. The stability and uniformity of both data and servo sensor elements is enhanced through the use of a grating profile under both the soft film biased magnetoresistive sensor layer and the hard bias stabilizing magnets. Processing steps are eliminated by replicating the grating pattern for the servo sensor elements through a thick layer of alumina or silicon dioxide. The outer read shield is removed from the servo elements using a stripping process that eliminates structural damage arising from alumina pinholes. Both element types are free of significant Barkhausen noise and instability because of the grating-stabilized domains in both the active magnetoresistive regions and the passive hard-biasing regions of each sensor. Each servo sensor is disposed at a greater distance from the single shield to optimize the microtrack profile. The resulting reduction in servo sensor frequency response leaves sufficient bandwidth for precise servo positioning.

Hard-film stabilized soft-film biased magnetoresistive sensor with an

An arbitrary pattern write head assembly for writing timing-based servo patterns on magnetic storage media is provided, comprising: (a) a first pole piece comprising a substrate comprising a magnetic material, said substrate having a major surface; (b) a plurality of electrically conducting windings formed on the major surface; and (c) a second pole piece formed on the substrate, with a portion thereof formed above the plurality of electrically conducting windings and electrically insulated therefrom, the second pole piece having at least one opening therethrough defining a gap above the electrically conducting windings and the substrate, the second pole piece comprising at least two layers, each layer comprising a magnetic material. A method of batch fabricating servo writer heads is also provided for batch fabrication of servo writer heads at a very low cost. The method enables fabrication of heads capable of azimuthal recording commonly practiced in the video recording art. Hard nitrided Fe/NiFe poletip materials are used to minimize wear in tape head use.

Process for fabricating an arbitrary pattern write head

Arbitrary pattern write head assembly for writing timing-based servo

A magneto-resistive (MR) head includes protection from electrostatic discharge without introducing additional processing steps. The MR sensor comprises a soft film biased (SFB) magnetic read sensor sandwiched between two high resistivity magnetic materials. The MR sensor is located between two MR shields wherein each MR shield is connected to an MR sensor ground signal lead by a resistor. The resistor is constructed from the high resistivity magnetic material such that the resistor is deposited at the same process step as the MR sensor.

Electrostatic protection for a shielded MR sensor

A magnetic head assembly is provided which has top and bottom zones for processing a magnetic tape alternately in opposite directions. Each zone contains a top write element and read element pair and a bottom write element and read element pair, the write element of each pair being located on a first gap line and the read element of each pair being located on a second gap line. Located between the read elements on the second gap line are a plurality of servo elements. The pitch of the servo elements is a multiple of the track pitch of the magnetic tape and the pitch of the write elements is a multiple of the pitch of the servo elements. The servo elements are totally dedicated to servoing on pre-recorded servo tracks on the magnetic tape. A servo element on the first gap line is on a common servo track with one of the servo elements on the second gap line so as to provide a pair of servos on the same servo track. During initialization of the tape drive, this pair of servo elements transmits signals to compensate for any track misregistration (TMR) due to head assembly inaccuracies during fabrication or tape skew. The bottom zone of the head assembly is a mirror image of the top zone. Each of the servo elements in the same gap line sequentially servo through all of the servo tracks so that the write elements in the same gap line can write a top and bottom sets of data tracks. When one servo element transition through all of the servo tracks, then the adjacent servo takes over and transitions through all of the servo tracks and so on until all of the sets of write tracks have been completed. This servoing and writing operation alternates between the top and bottom zones sequentially as the tape reverses its direction, one tape pitch at a time. When one of the zones is operational, one of its servos is a primary servo and the mirror image of this servo in the opposite zone serves as a back-up auxiliary servo for maintaining the write elements on track. When a scratch or tape defect is detected by the primary servo, control is transferred to the auxiliary servo to maintain the write elements on track.

Decoupled magnetic head assembly for quarter-inch tape

An interleaved bi-directional magnetic tape head for contact recording can have a poletip enhanced by providing a thin film of a soft magnetic material deposited onto a magnetic ferrite substrate. The second pole piece is a thin film of the soft magnetic material. A closure block of a non-magnetic ceramic encloses the layers together with leveling insulation layers and a deposited activating conductor turns. The stripe poletip deposited onto the magnetic ferrite extends for a distance just short of the first conductor turn and provides a balancing of the saturation moment of the pole pieces and provides for better recording capability, especially when operating in a trailing magnetic ferrite mode.

Magnetic head with magnetic substrate and an enhanced poletip thereon

An interleaved head for reading and writing data transitions onto a magnetic tape. A magnetic recording system for the bi-directional transportation of the tape media across the interleaved head. A controller controls the tape drive in a reel-to-reel format to accomplish the bi-directional motion of the tape media. The interleaved head includes two modules with each module having a plurality of alternating read and write transducers alternately spaced apart along a single line placed transverse to the movement of the magnetic tape. The two modules are placed together such that the write gaps of one module are aligned with the read gaps of the other module. Each read module includes the magneto-resistive element. Each write transducer includes a thin film conductor driving a nickel zinc ferrite substrate as one pole piece and a nickel zinc closure piece as the second pole piece. In order to provide leveling across the write transducers of the module, write back gap islands are provided in the back gap regions of the write transducer made of the same material with the same thickness as the magneto resistive element and the conductors interconnecting the magneto resistive element to the read/write network of the tape drive.

Magnetic hybrid interleaved head with closure supporting islands

Method of making a magnetic hybrid interleaved head

An interleaved bi-directional magentic tape head for contact recording can have a poletip enhanced by providing a thin film of a soft magnetic material deposited onto a magnetic ferrite substrate. The second pole piece is a thin film of the soft magnetic material. A closure block of a non-magnetic ceramic encloses the layers together with leveling insulation layers and a deposited activating conductor turns. The stripe poletip deposited onto the magnetic ferrite extends for a distance just short of the first conductor turn and provides a balancing of the saturation moment of the pole pieces and provides for better recording capability, especially when operating in a trailing magnetic ferrite mode.

Method for making magnetic head with enhanced poletip

A soft film biased magnetoresistive sensor (10) is fabricated to have reduced Barkhausen noise. The magnetic ratio of the film layers (14 and 18) is controlled to be in the range of 1.7 to 1.95 and the optimum bias point is controlled to be in the range of 35 and 41 degrees.

Very low noise magnetoresistive sensor for high density media

An NMR (nuclear magnetic resonance) spectrometer has a permanent magnet provided with a field coil. A lock system cyclically pulses a deuterium lock sample to produce a FID (free induction decay) signal that is analyzed by measuring the time interval during which the FID signal crosses the zero axis a predetermined number of times. The measured interval is compared to a predetermined interval or set point, and the current through the field coil is adjusted in the direction tending to correct the field strength so as to maintain the measured interval equal to the preset interval. Such measurement, comparison and adjustment are done several times each second. When the sample is removed, the lock system retains the last field setting achieved with the sample.

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Tucson, AZ, United States of America

Vincent N Kahwaty