Western Digital Technologies, Inc.

Seagate Technology Incorporated

Maxtor Corporation

Maxtor Corporagion

Brian P Rigney

Siri S Weerasooriya

Edgar D Sheh

Charles A Park

Jianbin Nie

Jason Laks

Bruce A Liikanen

Lin Guo

Yuan Chen

Yu Sun

Stanley H Shepherd

Stan Shepherd

Scott A Ottele

Xin Yang

Steven C Smith

Todd Franks

Guoxiao Guo

Don Brunnett

Wei Guo

Jiangang Liang

Michael A Chang

John L Seabury

Wing Ying

David Scott McMurtrey

Yakov M Lifchits

Yun Hong

Boworn Panyavoravaj

S Craig Smith

Tim Everett

Dave McMurtrey

Craig Smith

Brandon P Smith

Konrad Kummli

Richard Dennis Lesage

Yap Han Ng

Songwut Jomthaisong

A data storage device is disclosed comprising a disk surface comprising a first spiral track at least partially overwritten by a second spiral track, and a head actuated over the disk surface based on the second spiral track. The first spiral track comprises a periodic pattern written at a first frequency, and the second spiral track comprises a periodic pattern written at a second frequency different from the first frequency.

Data storage device attenuating interference from first spiral track when reading second spiral track

A disk drive is disclosed comprising a plurality of disk surfaces including a first disk surface and a second disk surface. The disk drive further comprises a plurality of heads including a first head actuated over the first disk surface, and a second head actuated over the second disk surface, as well as a ramp proximate an outer diameter of the disk surfaces. A first interval is measured while moving the first head toward the ramp until the first head contacts the ramp, and a second interval is measured while moving the second head toward the ramp until the second head contacts the ramp.

Disk drive measuring radial offset between heads by detecting a difference between ramp contact

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks including a first spiral track. A DC spiral track error common to the spiral tracks is measured relative to an ideal slope for the spiral tracks, and an AC spiral track error is measured for each spiral track relative to the ideal slope. As the head approaches the first spiral track, a spiral crossing window is opened based on the measured DC spiral track error and the measured AC spiral track error for the first spiral track, and the first spiral track is detected after opening the spiral crossing window.

Disk drive opening spiral crossing window based on DC and AC spiral track error

A data storage device is disclosed comprising a disk surface comprising a first spiral track, and a head actuated over the disk surface. While reading the first spiral track on the disk surface, a second spiral track is simultaneously written on the disk surface. In one embodiment, the second spiral track is written in an opposite radial direction as the first spiral track, and in another embodiment the second spiral track is written in the same radial direction as the first spiral track.

Data storage device reading first spiral track while simultaneously writing second spiral track

A data storage device is disclosed comprising a first disk surface comprising servo tracks defined by servo sectors and recorded at a first radial density, and a first head actuated over the first disk surface. A servo sector on the first disk surface is read to generate a first physical position measurement that is converted into a first virtual position measurement corresponding to a nominal radial density of servo tracks different from the first radial density. The first head is servoed over the first disk surface based on the first virtual position measurement.

Data storage device servoing heads based on virtual servo tracks

A disk drive is disclosed comprising a voice coil motor (VCM) configured to actuate a head over a disk. The VCM is controlled to seek the head over the disk during a first seek, and a back electromotive force (BEMF) voltage generated by the VCM during the first seek is measured. Feed-forward compensation is generated based on the measured BEMF voltage, and the VCM is controlled to seek the head over the disk during a second seek using the feed-forward compensation while writing servo data to the disk.

Disk drive using VCM BEMF feed-forward compensation to write servo data to a disk

A disk drive is disclosed comprising a head actuated over a disk, and a ramp near an outer diameter of the disk, wherein the ramp for unloading the head off the disk. The head is positioned at an inner diameter of the disk and then moved toward the ramp in response to a velocity profile. An interval is measured from a beginning of the movement until the head begins unloading onto the ramp, and the velocity profile is adjusted in response to the measured interval.

Disk drive calibrating a velocity profile prior to writing a spiral track

A disk drive is disclosed comprising a disk surface comprising a radius, a head operable to generate a read signal, and a voice coil motor (VCM) operable to actuate the head over the disk surface. A back electromotive force (BEMF) voltage generated by the VCM is measured. The VCM is controlled to move the head over substantially the entire radius of the disk surface in response to the BEMF voltage, and while moving the head the read signal from the head is processed to detect residual data recorded on the disk surface after erasing the disk surface.

Disk drive performing spiral scan of disk surface to detect residual data

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks, each spiral track comprising a high frequency signal interrupted at a predetermined interval by a sync mark. The head is used to read the spiral tracks to generate a read signal representing spiral track crossings. A position error signal (PES) is generated in response to the spiral track crossings, and the head is servoed over the disk in response to the PES. Timing feed-forward compensation values are generated in response to the PES, and the timing feed-forward compensation values are used to open a demodulation window at each spiral track crossing, wherein the timing feed-forward compensation values compensate for a repeatable runout (RRO) of the spiral tracks.

Disk drive adjusting demodulation window for spiral track using timing feed-forward compensation

A disk drive is disclosed comprising a disk, a head, and a voice coil motor (VCM) operable to actuate the head over the disk, wherein the VCM generates a back electromotive force (BEMF) voltage. At least one reference track is written on the disk, and the head is positioned near a first diameter of the disk. While moving the head from the first diameter toward a second diameter of the disk, the reference track is read and a first estimated state error is measured. While moving the head from the second diameter of the disk toward the first diameter of the disk, the reference track is read and a second estimated state error is measured. A gain and an offset of a velocity sensor are adjusted in response to the first and second estimated state errors.

Disk drive adjusting gain and offset of BEMF velocity sensor during self writing of spiral tracks

A disk drive is disclosed comprising a head actuated over a disk, wherein a bootstrap spiral track is written on the disk. While servoing on the bootstrap spiral track at least one circular reference track is written on the disk. A velocity profile is adjusted in response to the circular reference track, and a plurality of spiral tracks are written to the disk in response to the velocity profile.

Disk drive performing in-drive spiral track writing

A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. A bootstrap spiral track is written to the disk, wherein the bootstrap spiral track comprises a high frequency signal interrupted by sync marks. A first sync mark is written while writing a first part of the bootstrap spiral track, and a second sync mark is written while writing a second part of the bootstrap spiral track. A switch between writing the first sync mark and the second sync mark is made in response to a spindle BEMF voltage, thereby generating a sync mark seam in the bootstrap spiral track.

Disk drive writing a sync mark seam in a bootstrap spiral track

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks. During a seek operation, a demodulation window is opened in response to a window offset during a first revolution of the disk, wherein the demodulation window corresponds to the head approaching a spiral track. A window position error signal (PES) is generated representing a difference between a target framing of the demodulation window around the spiral track crossing and a detected framing of the demodulation window around the spiral track crossing. The window offset is adjusted in response to the first window PES, and the demodulation window is opened in response to the adjusted window offset during a second revolution of the disk.

Disk drive centering demodulation windows on spiral tracks during a seek operation

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks. A first sync frame is first opened in response to a first frame offset during a first revolution of the disk, wherein the first sync frame corresponds to the head approaching a first sync mark in a first spiral track crossing. A first sync frame position error signal (PES) is generated representing a difference between a target framing of the first sync frame around the first sync mark and a detected framing of the first sync frame around the first sync mark. The first frame offset is adjusted in response to the first sync frame PES, and during a second revolution of the disk the first sync frame is second opened in response to the adjusted first frame offset.

Disk drive centering sync frames on sync marks of a spiral track

Method and apparatus for detecting a reference pattern in a transmitted bit sequence. A duration of a search window used to detect the reference pattern is adaptively adjusted in relation to a previous detection of the pattern. This is preferably carried out by using a first search window to initially detect the pattern, and then adjusting the first search window to provide a second search window to subsequently detect the pattern. Preferably, the search window is an elapsed period of time during which a transducer is swept adjacent a storage medium to detect the reference pattern. Servo data are preferably written as a sequence of adjacent spiral servo patterns, and the reference pattern is preferably detected each time to determine the relative location of the most recently written spiral. Preferably, a larger search window is used for initial spirals and a smaller search window is used for subsequently written spirals.

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Louisville, CO, United States of America

Brian P Rigney