Seagate Technology Incorporated

Maxtor Corporation

Ralph William Cross

Xiong Liu

Mourad Benakli

Kirill A Rivkin

Todd Michael Lammers

Quan Li

Chris Broussalian

Wenzhong Zhu

Mehmet Fatih Erden

Barmeshwar Vikramaditya

Scott Robert Warmka

Edward Charles Gage

Michael L Mallary

Wei Tian

Huaqing Yin

Jianhua Xue

Kenneth A Haapala

Dian Song

Javier Ignacio Guzman

Beng Theam Ko

Peter Stuart Harllee, Iii

Michael R Montemorra

A sequence of symbols is generated to describe a set of write data, the symbols having a length of nT, where T is a channel clock rate and n is an integer over a predetermined range. Bi-directional write currents are applied to a write pole to record the sequence of symbols to a magnetic storage medium. The write pole has an effective footprint with a downtrack length of mT, where m is an integer. The write currents are switched between a first rail current and a second rail current for alternating symbols, the write currents further transitioning to an intermediate current value for at least one channel clock period for symbols longer than 1T. Write currents are applied to the write pole when recording symbols having a length longer than mT using the effective footprint of the write pole as an interval.

Write current switching in a data storage device using an effective footprint of a write pole

Systems and methods for a providing a chirped current profile with an undershoot for a channel preamplifier are described. A method for writing bits in a magnetic recording disc may include applying an overshoot to a write current which is supplied to a magnetic writer of the magnetic recording disc and applying an undershoot to the write current after the overshoot is applied to at least partially de-saturate the magnetic writer. The method may also include writing a bit to the magnetic recording disc with the magnetic writer using the supplied write current. In some examples, the application of a short negative pulse after an overshoot portion of the write current waveform is delivered to the head during a write operation that writes the bit to the magnetic recording disc.

Chirped current profile with undershoot feature

A storage device includes a storage medium and a transducer head with two writers positioned to write to a same surface of the storage medium. The two writers are separated from one another along a down-track direction of a data track on the storage medium and independently controllable to write data.

Dual writer head design utilizing two writers of different sizes for writing interlaced data tracks

Method and apparatus for enhancing write current switching efficiencies during data write operations in a data storage device. In some embodiments, write data are described in the form a sequence of symbols of nT length where T is a channel clock rate and n is an integer over a selected range. Bi-directional write currents are applied to a write element to record the sequence of symbols to a storage medium. The write currents are switched between a first rail current and a second rail current for alternating symbols. The write currents are further transitioned to an intermediate current value for at least one channel clock period immediately preceding a next occurrence of a symbol boundary between an adjacent pair of symbols in the sequence.

Write current switching in a data storage device

Method and apparatus for controlling the position of a control object in a closed loop control system, such as a servo control system used in a data storage device. In some embodiments, spaced apart first and second data tracks are written to a rotatable data recording medium without using repeated runout (RRO) compensation values to correct for RRO error in servo data written to the medium. A third data track is subsequently written so as to be interspersed between and partially overlap the first and second data tracks. The third data track is written using a set of RRO compensation values to correct for the RRO error in the servo data.

Repeated runout (RRO) compensation for alternating tracks in an interlaced magnetic recording system

A readback signal from a first reader and a readback signal from a second reader are received, the first reader and the second reader configured to read two-dimensional data from at least one track of a recording media. A quality metric of the second reader is measured based on the readback signal. It is determined if the quality metric for the second reader is above a threshold. If the quality metric is above the threshold, the first reader and the second reader are used to read the data.

Requirement relaxation for multiple readers in presence of large skew angle range

A transducing head for use with a storage medium rotatable about an axis includes first and second writers for writing to the storage medium. The first writer is configured for dedicated writing to a first radial region of the storage medium, and the second writer is configured for dedicated writing to a second radial region of the storage medium. The second radial region is located radially outward from the first radial region.

Dedicated ID-OD writer with beveled pole tips and method of manufacture

A read/write head for a disk drive having a magnetoresistive (MR) read element and an inductive write element suitable for perpendicular recording of data onto a disk having a media layer in which the data is stored perpendicularly to the planar surface of the disk and a soft underlayer (SUL) underneath the media layer to provide a low reluctance return path for the magnetic recording field. The write element is formed on top of a substrate, with the read element on top of the write element on the other side of the write element from the substrate. A pancake write coil coils around a magnetic via that either connects to a write shield adjacent to the read element in one embodiment or directly to one of the read shields in a second embodiment.

Shielded pole writer under reader

A read/write head for a disk drive having a shorting conductor from a shield of the read element to a conductor that runs from the write element to an external electrical contact pad. This allows for the measurement of the electrical isolation between the read sensor and the read shield via the external contact pads. Such a capability allows the electrical isolation to be measured both during the lapping process and subsequent to the heads being diced into separate sliders. This shorting conductor may be in the form of an internal shorting stud or in the form of an interim conductor that passes through the parting zone between adjacent heads. In the latter case, the shorting conductor is broken when the heads are diced so that a head of this embodiment can only be measured for electrical isolation prior to dicing.

Methods of slider-level reader isolation measurement technique for advanced GMR heads

Slider-level reader isolation measurement technique for advanced GMR heads

A process for manufacturing a GMR read element of a read/write head for a disk drive having pattern exchange biasing for longitudinal stabilization. An in situ or ex situ GMR anneal of the pinned layer occurs after only the AFM pinning layer and the first pinned layer have been deposited. After the anneal, the upper surface of the first pinned layer is milled with low energy ions to remove oxidation and SIMS inspection determines the amount of oxidation removed and the amount of surface modification required for smoothing. After this, the remaining layers are deposited through the exchange bias layer. A second anneal is then performed at a somewhat lower temperature than the GMR anneal. In this manner, the entire stack is not subjected to the GMR anneal, the upper surface of the first pinned layer can be optimized, and the interface between the free layer and the exchange biased layer is not disturbed.

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Lyons, CO, United States of America

Ralph William Cross