Seagate Technology Incorporated

Jason Wayne Riddering

Zine-Eddine Boutaghou

Huazhou Lou

Wayne Allen Bonin

Lance Eugene Stover

Drew Michael Mader

Zine Eddine Boutaghou

Alfredo Sam Chu

Anthony Pascal Sannino

Mary Cynthia Hipwell

Jing Gui

Daniel Paul Burbank

John Stuart Wright

Huan H Tang

Neal Frank Gunderson

Jorge Vicente Hanchi

Michael David Mundt

Wenzhong Zhu

Roger Lee Hipwell, Jr

Peter Raymond Segar

Kenneth A Haapala

James Morgan Murphy

Timothy William Stoebe

Brian William Karr

Joshua Ward Christensen

Markus Erwin Mangold

Jianxin Zhu

Andrew Robert Motzko

Lin Zhou

Dongming Liu

James E Angelo

Richard Edward Martin

Stefan Andrei Ionescu

Mark Andrew Chapin

Gary Edwin Bement

Kevin John Grannen

Dustin Mark Cvancara

Pu-Ling Lu

Joshua Charles Harrison

Antanas Daugela

Subra Nagarajan

Mukund Channagiri Rao

Bin Huang

Rick Pfahl Freeman

Youping Mei

Lee Clifford Knippenberg

James Richard Peterson

Shawn Stephen Silewski

Steven J Kimble

Jane Katherine Gates

Eric John McCalla

Michael P DeFeo

Erick J Lindquist

A clearance heater of a write head is engaged with a boosted current that exceeds a steady-state current. The steady-state current causes the write head to maintain a desired clearance over a disk during writing, the boosted current being applied before a start of the writing. The boosted current is monotonically decreased before the start of the writing and the steady-state current is applied to the heater after the start of the writing.

Boosted preheat trajectory to obtain desired clearance before writing to disk

A heat-assisted magnetic recording head is moved relative to a magnetic recording medium. The medium comprises a plurality of sectors. The sectors define a plurality of sector groups distributed around a circumference of the medium. The sectors of each sector group are written using different operational currents supplied to a laser diode of the head such that at least one sector from each sector group is written using one of the different operational currents. For each of the different operational currents, an average write performance metric is calculated for all sectors written at each of the different operational currents. A particular operational current of the different operational currents is determined that results in a best average write performance metric.

Laser calibration for heat-assisted magnetic recording head using interleaved laser current

An apparatus comprises a slider configured for heat-assisted magnetic coupled to a controller. The slider comprises a writer, a heater, a near-field transducer, and an optical waveguide for communicating light from a laser diode to the near-field transducer. The controller is configured to set a target pre-write clearance of the slider prior to performing a write operation, set a target write clearance of the slider for performing the write operation, and determine a difference between the target pre-write and write clearances to define a target pre-write clearance offset. The controller is also configured to measure, for a plurality of different target pre-write clearance offsets, a writability metric for the slider while sweeping a laser diode current, and adjust the target pre-write clearance offset so that the writability metric reaches a predetermined threshold. The controller is further configured to perform subsequent write operations using the adjusted target pre-write clearance offset.

Calibration and adjusting target pre-write clearance offset for a heat-assisted magnetic recording device

A slider is configured for heat-assisted magnetic recording to a magnetic recording medium. A low- or non-modulation interface is defined between the slider and the medium. A contaminant is present on the slider and between the slider and the medium. A controller is configured to control the slider to dislodge the contaminant from the slider by performing modulation-based contact detection at a location of the medium where modulation-based contact detection can accurately detect head-medium contact. The controller is also configured to perform friction-based contact detection using the slider devoid of the contaminant.

Head-medium contact sensor cleaning for heat-assisted magnetic recording device

A lumped-parameter function &#x3b4; is determined that represents an average power dissipated by a write transducer when writing a signal to a magnetic recording medium. Temperatures of the write transducer are measured while varying the parameters to determine constants of the function &#x3b4;. The function &#x3b4; is used to adjust power applied to a clearance control heater when writing to the magnetic recording medium.

Lumped-parameter thermal model of a write transducer for clearance control on magnetic recording device

A change in servo active gain control values is determined from a beginning of a writing of a test region of a recording medium to an end of the writing of the test region. The servo active gain control values are read from servo marks by a read transducer of a read/write head during the writing. After writing of the test region, the test region is read by the read transducer to determine a change in recorded amplitude from the beginning of the writing to the end of the writing. A gamma value of the read/write head is determined based on the change in servo active gain control values and the change in recorded amplitude.

Determining gamma of a read/write head based on active gain control and test signal amplitude measurements

A heat-assisted magnetic recording (HAMR) head includes a reader, a writer, a writer heater, a laser, and a near-field transducer (NFT). A processor is coupled to the head and configured to perform laser writeability calibration of the head. The processor is also configured to concurrently while performing the laser writeability calibration, correct for laser induced writer protrusion (LIWP) at a writer/NFT region of the head using writer clearance calculations based on reader clearance measurements.

Concurrent laser induced writer protrusion correction and laser writeability calibration

A test involves iterations over a series of laser powers of a heat-assisted read/write head. The iterations involve writing to a recording medium at the selected laser power for a sufficient duration to ensure thermal equilibrium of the read/write head at an end of the write. A clearance-control heater of the read/write head is transitioned from a pre-write power before a start of the write to a steady-state write power. The iterations further involve measuring a temperature of the read/write head during the write and adjusting the steady-state write power to achieve a predefined difference between the temperature at the start of the write and the end of the write. The adjusted steady state write power is stored for each iteration. A write-induced protrusion is determined based on the iterations and used for calibration of the read/write head.

Determining write-induced protrusion as a function of laser power using temperature measurements

Method and apparatus for controlling the fly height of a transducer. In some embodiments, a data pattern is written to a rotating data recording surface using a transducer having a write element, a read element and a thermal assist energy source. A first protrusion distance for the read element induced by operation of the energy source is determined responsive to first and second readback amplitudes obtained from the data pattern using different first and second power levels applied to the energy source. A second protrusion distance for the write element induced by the energy source is determined responsive to the first protrusion distance.

Thermally assisted writer protrusion determination and control

An apparatus comprises a heat-assisted magnetic recording (HAMR) head, a sensor, and a controller. The HAMR head is configured to interact with a magnetic storage medium. The sensor is configured to produce a signal indicating the occurrence of head-medium contact. The controller is configured to receive the signal and concurrently determine from the signal if the occurrence of head-medium contact is caused by a first contact detection parameter, a second contact detection parameter, or both the first and second contact detection parameters.

Concurrent modulation and frictional heating head disk contact detection

A magnetic recording head comprises a transducer, a heater, a writer and a laser. The transducer is configured to write to a magnetic recording medium during a write operation. The heater, writer and laser are configured to affect a protrusion of the transducer. The heater is calibrated to produce a pre-write heater power to obtain a target pre-write clearance for a write operation through use of a clearance-heater power curve. The curve is generated by measuring a clearance between the transducer and the medium as the heater is cycled from zero to a contact power.

Heat-assisted magnetic recording head-disk clearance setting

A method includes setting a heat assisted magnetic recording (HAMR) device located in a data storage system having a laser to an operating temperature. A threshold laser current is determined. An optimal laser current is determined. The threshold laser current and the optimal laser current are stored in memory. The steps of determining a threshold laser current, determining an optimal laser current and storing the threshold laser current and the optimal laser current into the calibration table are repeated until acceptable device performance is achieved at more than one operating temperature.

Laser temperature calibration in a HAMR device

A power level is applied to a laser that heats a heat-assisted recording medium is increased during recording for a plurality of iterations. Each iteration involves writing test data to a plurality of sequential tracks of the recording medium using the power level and determining bit error rates of the test data. Based on the bit error rates of the iterations, a power boost profile is determined. The power boost profile starts at a baseline level at a first track of a plurality of sequentially-written tracks, incrementally increases to a steady-state level over a first portion of the tracks, and remains at the steady-state level over subsequent ones of the tracks. The power boost profile is applied to the laser when recording to the recording medium.

Current boost profile applied to laser during heat-assisted magnetic recording

Fixed patterns are written on a track of a heat-assisted, recording medium at multiple, heater-induced write clearances via a recording head. The writing involves heating the recording medium via a near-field transducer of the recording head. Amplitudes of the fixed patterns are read back at a predetermined read clearance. A clearance difference between a start and an end of a first data sector of the track is determined based on the amplitudes. A narrow, laser-induced protrusion is estimated at the near-field transducer based on the clearance difference.

Estimating narrow, laser-induced protrusion at a near-field transducer

A channel senses head-to-disc contact vibrations in a vibrational noise spectrum produced in a mass storage device. The channel includes a suspension system with a suspension modal resonance. The channel includes a vibration sensor that senses head-to-disc contact vibrations through the suspension system. The vibration sensor has a sensor modal resonance that overlaps the suspension modal resonance.

Resonant channel for head-to-disc contact vibrations

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Prior Lake, MN, United States of America

Jason Wayne Riddering