Maxtor Corporation

International Business Machines Corporation

Seagate Technology Incorporated

John Charles Purkett

Bruce A Liikanen

Don Brunnett

Richard Greenberg

Lace J Herman

Bobby Ray Southerland

Jin-Hong Hsueh

Thomas O Melrose

Moris Musa Dovek

Lin Guo

Yu Sun

David L Schell

Timothy Francis Ellis

Mark David Hagen

Robert A Alt

Joshua Ward Christensen

Kevin Jack Erickson

Dana H Brown

Justin Won

Ravi Hebbar

Jim Hargarten

KarWei Koay

Timothy J Blank

Matthew McLeod Chadsey

Terry Keefer

Georgie Tan

A circuit may be configured to adjust a correction signal for each phase of an electric motor based on a rotational position of a spindle of the electric motor, generate a distorted waveform based on the correction signal, and drive the electric motor in response to the distorted waveform. In some examples, back electromotive force (BEMF) may be determined in order to adjust a motor drive waveform, which may reduce or eliminate motor vibrations. A motor drive signal may be pre-warped (i.e. distorted) such that when the correctional signal and drive signals are combined, there is a reduction in acoustic emissions or motor vibrations. Other parameters, such as cogging torque, may be measured to reduce motor vibration and acoustic emissions.

Torque disturbance cancellation for a motor

Systems and methods are disclosed for writable servo zone overlap regions on a disc memory. An apparatus may comprise a controller configured to determine a servo gate (sgate) timing for an overlap zone including servo patterns of a first servo super zone and a second servo super zone of a disc memory, the sgate timing based on servo pattern timing for the first servo super zone and the second servo super zone. The controller may initiate writing to the overlap zone based on the sgate timing. The controller may also reduce the impact of servo pattern frequency change between zones by calculating a trajectory error prior to the crossing, and providing 1/X of the trajectory error into a servo feedback loop for a following X servo sampling points.

Writable servo overlap zones

Apparatus and method for mitigating impedance changes in a microactuator conductive joint. In accordance with some embodiments, a microactuating element has a conductive input junction, the junction having dissimilar metals in contact with one another. The microactuating element is adapted to mechanically deform to displace a control object responsive to a micractuation control signal that is applied to the junction. A control circuit applies a bi-directional transition signal to the conductive input junction to reduce an increased impedance of the junction.

Impedance mitigation of a microactuator conductive joint

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

Dynamically detecting off-track errors in a disk drive by adjusting transducer head position control parameters in response to shock events. In an embodiment, shock events with large magnitude trigger a severe shock timer which lengthens the write fault before write operations resume. In another embodiment, a lower shock threshold is used following an initial shock event. In yet another embodiment, a lower shock threshold is used if an accumulated average position error of the transducer head is large.

Dynamic shock detection in disk drive using hair trigger timer

A disk drive provides increased read and write element widths and tolerances, and also provides reduced track widths. The head with the read and write elements has a large skew angle relative to the tracks on the disk. The skew angle reduces the effective width of the read and write elements. Based on this reduction in effective width, the physical width of the read and write elements may be increased. Furthermore, the width of the tracks may be reduced instead of, or in addition to, the increased read and write element width.

Method and apparatus for reducing effective track width through highly skewed head angles

Dynamic shock detection in disk drive using accumulated average position error

A method and apparatus for determining embedded runout correction values when self-servo writing or partial self-servo writing is disclosed. In one embodiment, a disk surface, which has servo information written thereon, is provided. The servo information is grouped intoservo sectors andservo sectors, and theservo sectors and theservo sectors form a plurality of tracks. A read head servos on theservo sectors associated with a track. Both position error signals due to repeatable runout for theservo sectors and information related to position error signals due to repeatable runout for theservo sectors are determined, while servoing on theservo sectors. Embedded runout correction values for theservo sectors and theservo sectors are calculated.

Method and apparatus for determining embedded runout correction values when self-servo writing or partial self-servo writing a disk drive

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.

Method and apparatus for automatically determining an embedded runout correction threshold

A method and apparatus for dynamically detecting write fault errors is provided. According to the invention, transducer head control parameters are adjusted according to observed events. For instance, off-track events of a certain magnitude may trigger the implementation of a severe shock timer, which lengthens the delay between the off-track event and allowing write operations to resume, as compared to the standard off-track timer. According to another embodiment of the present invention, a lower write fault threshold is implemented following an off-track event of sufficient magnitude. According to yet another embodiment of the present invention, the average or accumulated position error of the transducer head is monitored, and a lower write fault threshold implemented if the average position error exceeds a threshold value. The present invention's provision of a method and apparatus that enables transducer head control parameters to be modified in response to observed off-track events allows the disk drive to provide high resistance to data loss without significant detrimental effects on the data throughput performance of the disk drive.

Dynamic off-track detector

A magnetic storage system is disclosed which has one or more rotating disks. In one embodiment, the system includes a first transducer and a second transducer operatively associated with a respective first surface or second surface. Each of the first and second surfaces has a data track with a data region and an embedded servo sector. The first transducer has a data reader which includes a first MR strip and a servo reader which includes a second MR strip. The first MR strip is electrically isolated from the second MR strip. The first transducer performs a servo reading operation of the servo sector while the second a transducer performs either a data writing operation to the data region or a data reading operation from the data region. Also disclosed is a method for reading within a magnetic storage system. The storage system includes a first magnetic surface, a data reader and a servo reader. The first magnetic surface includes a first data region and a first servo sector. The data reader is not coupled to the servo reader. Servo information is read with the servo reader so that an off-track position of the data reader can be determined. After the off-track position is known, the data reader is moved to compensate for the off-track position. Once the data reader is properly positioned, the data reader retrieves user data from the first data region of the first magnetic surface.

Transducer head with separate data and servo read elements

An apparatus for correcting read errors in a disk drive is disclosed. In one embodiment, the apparatus includes circuitry for determining that an undesired distortion exists in a data signal read from a surface of a data storage disk; circuitry for finding an approximate starting location of said distortion within said data signal; and, circuitry for correcting errors in said data signal caused by said undesired distortion using said approximate starting location of said distortion. A method for correcting read errors in a disk drive is also disclosed. In one embodiment, the method includes the steps of (1) providing an error correction code (ECC) that is capable of locating and correcting errors in a data signal; (2) determining that a data signal read from a surface of a data storage disk includes a distortion; (3) finding an approximate starting location of said distortion within said data signal; and, (4) performing error correction procedures on said data signal, based on said ECC, using said approximate starting location of said distortion

Method of correcting a read error in a disk drive

A phase modulated servo method and apparatus provide acceptable position linearity for servo positioning with a narrow transducer head in a disk file. The disk file includes at least one disk mounted for rotation about an axis and the disk has at least one disk surface for storing data and has at least one transducer mounted for movement across the disk surface for writing to and for reading data and servo patterns from the disk surface. The transducer includes a read element and a write element. The read element has a width less than the write element and the read element width is greater than &frac13; of a data cylinder and less than &frac12; of a data cylinder. A servo pattern is written on the data disk surface having a track pitch of less than &frac12; of a data cylinder and the servo pattern repeats in a selected binary number of data cylinders.

Method and apparatus for servo positioning in a direct access storage device with a transducer read element width greater than &frac13; and less than &frac12; width of a data cylinder

An apparatus for correcting read errors in a disk drive is disclosed. In one embodiment, the apparatus includes circuitry for determining that an undesired distortion exists in a data signal read from a surface of a data storage disk; circuitry for finding an approximate starting location of said distortion within said data signal; and, circuitry for correcting errors in said data signal caused by said undesired distortion using said approximate starting location of said distortion. A method for correcting read errors in a disk drive is also disclosed. In one embodiment, the method includes the steps of (1) providing an error correction code (ECC) that is capable of locating and correcting errors in a data signal; (2) determining that a data signal read from a surface of a data storage disk includes a distortion; (3) finding an approximate starting location of said distortion within said data signal; and, (4) performing error correction procedures on said data signal, based on said ECC, using said approximate starting location of said distortion.

Method of correcting read errors in a data storage system using targeted

A system and method for encoding a servo address in a disk drive system having at least one disk for storing data is disclosed. A servo address associated with a sector in a track, or cylinder, on a surface of a disk and comprised of a sector number, a track number, and in multiple disk systems, a head number is encoded into the encoded servo address. Encoding the servo address saves disk storage space because the encoded servo address uses fewer bits than a conventional servo address while still enabling the disk drive system to verify the location of any sector.

Growing community of inventors

Longmont, CO, United States of America

John Charles Purkett