Maxtor Corporation

Seagate Technology Incorporated

Thomas O Melrose

James W Hargarten

Bruce A Liikanen

Don Brunnett

Lloyd E Levy

John Charles Purkett

Michael McNeil

Jim Hargarten

Stephen H Perlmutter

Adrián Cerdá

Yu Sun

Keith W Malang

Timothy John Everett

Dave Finamore

Andy Ottele

Various embodiments of the present invention are generally directed to adaptively determining an updated repeated runout (RRO) correction value to correct for RRO error in the placement of a servo seam, by iteratively combining a weighted initially estimated RRO correction value for the seam with a position error signal (PES).

Repeated runout error compensation using iterative feedback

Apparatus and method for compensating for positional indicia misplacements in the positioning of a control object, such as with servo seam misplacements on a data storage device storage medium. An actual position for the control object is determined in relation to a corrected commanded position of the control object and a corrected position error of the control object. The corrected commanded position is determined in relation to a gain error and an actual commanded position, and the corrected position error determined in relation to the gain error and an actual position error. Preferably, an actual position error of the control object is next determined in relation to the actual position, and the control object is moved to reduce the actual position error. The positional indicia preferably comprise AB and CD seams of ABCD servo dibit patterns on a recording surface.

Positional indicia misplacement compensation

Various embodiments of the present invention are generally directed to propagating repeated runout (RRO) correction values for radially concentric servo seams on a storage medium in relation to an RRO correction value for an adjacent seam and a radial separation between the seams.

Seam to seam embedded runout correction propagation

A disk drive self-servo writes on a storage disk. Servo bursts are self-written along a track using a transducer, a position error signal (PES) indicating repeatable runout due (RRO) for the servo bursts is determined using a reference pattern, an embedded runout correction (ERC) value is calculated based on the PES and stored in a corresponding servo sector, and then the disk drive self-writes other servo bursts.

Disk drive during self-servo writing

In accordance with various embodiments, a radial separation distance between first and second servo seams on a storage medium is determined, and a scaled position signal is generated in relation to the determined radial separation distance and a measured position signal. An error runout correction (ERC) value is obtained from the scaled position signal, and the ERC value is thereafter used to compensate for repeated runout (RRO) error.

Repeated runout compensation using scaled position signals

Performing embedded runout correction for a track on a rotational data storage disk includes measuring written-in runout for the track, selecting a number of revolutions in response to the measured written-in runout of the track, calculating embedded correction values for the track for the selected number of revolutions of the rotational data storage disk, and storing the embedded correction values.

Embedded runout correction based on written-in runout measurement

An apparatus and associated method is provided for observing a positional misplacement of a control object at a first commanded position, defining a fault threshold as a function of the observed positional misplacement, and signaling a write unsafe command to the control object in relation to comparing an instantaneous positional misplacement of the control object to the defined fault threshold during self servo writing with the control object.

Adaptive write unsafe thresholds for self servo writing

A disk drive measures the radial misposition of tracks and repositions the tracks at regularly spaced intervals. Written in runout (WRO) in servo bursts is determined to calculate track spacing and squeeze among adjacent tracks. Tracks with improper spacing are repositioned by adding a squeeze correction term to the servo wedges. Thereafter, when the disk drive operates to store data, the servo bursts are used to calculate a position error signal (PES), and the squeeze correction term is combined with the PES to position the head at a proper track radius.

Method to correct radial misposition of data tracks using stitched correction fields

A method of reducing microjog errors in a disk drive having a data recording disk with data tracks and a transducer head positionable on the tracks. The head includes a writer element offset from a reader element. To reduce microjog errors, track squeeze is measured at a number of locations across the surface, wherein the squeeze is due to mis-positioning of the track relative to neighboring tracks. A microjog distance for the destination track is provided, and a microjog correction value based on the measured track squeeze is calculated. The correction value is applied to the microjog distance to obtain a corrected microjog distance that reduces microjog errors due to track squeeze.

Method to compensate for microjog error induced by localized track squeeze

Method and apparatus for runout correction during self-servo writing

A method and apparatus for determining embedded runout correction values uses a closed-loop system (with feedback) in a disk drive. Optionally, the embedded runout correction values may be determined after the disk drive has been manufactured and placed in the field. In addition, the embedded runout correction values may be updated after the disk drive has been manufactured and placed in the field.

Method and apparatus for determining embedded runout correction values using feedback

A method and system for self-writing track locations of a data disk in a disk drive in order to reduce overall track runout are disclosed. First set of servo bursts are self-written along a track via a transducer, and repeatable runout correction values for the first servo bursts are calculated. Then, second servo bursts are self-written along the track via the transducer such that the first and second servo bursts form a plurality of servo sector patterns that define the track centerline, wherein the second servo bursts are positioned using said correction values to essentially compensate for the runout in the first servo bursts and reduce the overall track runout.

Method and apparatus for runout correction by proper positioning of servo data while self-servo writing

A disk drive utilizes a unique write condition for each of the transducers within the drive. Each write condition is determined based upon the specific properties of the corresponding transducer. The write condition information is preferably stored within a memory within the disk drive. When a write operation is performed, the appropriate write condition for the corresponding transducer is used to determine when to write data to the disk. A write condition will typically include one or more individual write criteria. For example, a write condition can specify a write threshold value to be used during a write operation. A write fault threshold value is selected for each transducer by determining a position error distribution corresponding to that transducer wherein the position error distribution is essentially a function of random noise associated with the disk drive, and by using that distribution to determine allowable off-track threshold value (WFL), will protect the drive from encroachments.

Method to accurately predict hard error rates resulting from encroachment

Method to correct radial misposition of data tracks

A method and apparatus for automatically determining an embedded runout correction threshold for a disk drive are disclosed. In prior systems, embedded runout correction thresholds were set for all disk drives in a production run. The present invention provides a technique for automatically determining an embedded runout correction threshold on a drive-by-drive basis, instead of a production run of drives basis.

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Longmont, CO, United States of America

Thomas O Melrose