International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Western Digital Technologies, Inc.

Gregory Michael Frees

Louis Joseph Serrano

David Robison Hall

Daniel Jonathan Auerbach

Jeffrey Joesph Dobbek

Craig N Fukushima

Daniel Robert Stacer

Masakazu Sasaki

Jeff J Dobbek

Fu-Ying Huang

Mantle Man-Hon Yu

David W Albrecht

Kirk Barrows Price

Hiroki Kitahori

Kiyoshi Satoh

Peter E Brooks

Zarko Popov

Shad Henry Thorstenson

Andrew Keith Hanlon

Donald Lee Clare

Hatem R Radwan

Andrew E Larson

Blake O Finstad

Sunao Nemoto

Markus Staudenmann

A data storage device is disclosed comprising a head actuated over a magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A plurality of access commands are stored in a command queue, and an access command is selected from the command queue. When the selected access command is a write command to a target data track and at least part of a first data track proximate the target data track needs to be refreshed, a refresh read command is executed to read data from at least part of the first data track prior to executing the write command to the target data track.

Data storage device executing just-in-time refresh

Tilt between a head stack and its associated disk stack in a hard disk drive (HDD) is measured by determining the deviation of a target head from its expected position (based on the position of the current head) each time electrical contact is switched from the current head to a target head. A running average tilt value is stored and used to modify the logical seek distance used in a Rotational Position Optimization (RPO) algorithm to better order I/O requests in a queue. Also, the running average tilt value can be used by the servo to pre-position the target head before electrical contact is made with the target head, to improve speed of operation.

System and method for correcting for head tilt in HDD

A mounting interface for a spindle motor allows the optimization of the spindle dynamics. The mounting interface provides a steadfast relationship between a motor and a baseplate, wherein the mounting interface includes at least three surface points forming a single plane acting as a common boundary between the motor and the baseplate. The three surface points may be pads, and the pads may be coupled to the baseplate or to the mount flange. The three surface points provide reduced contact area between the mount flange and the baseplate, and the reduced contact area lowers the rigidity of the mount flange and the resonant frequencies. The surface area of the pads and the material of the pads is chosen to reduce acoustical noise. In addition, a damping ring may be provided for dissipating distortion energy between the motor, baseplate and/or mount flange.

Mounting interface for a spindle motor

A system and method for precompensating for tangential misalignment in a direct access storage device adjusts a SID timing window individually for every track or surface of the direct access storage device. The system and method generate a calculation of the tangential misalignment and adjust, in accordance with the calculation of tangential misalignment, a timing window during which the transducer head reads the information located on the storage surface. The calculation of tangential misalignment may be the result of a direct measurement of the tangential misalignment, or may be converted from radial misalignment data. The adjustment of the timing window may comprise opening the timing window an amount depending upon the degree of misalignment of each track, and may comprise shifting the window in time either forward or backward depending upon the nature of the calculated misalignment.

Tangential misalignment precompensation in a direct access storage device

The fundamental vibration or butterfly mode sensitivity of a hard disk drive,is significantly dependent on the operating temperature of the drive. The temperature of the drive is readily determined via measurement with a thermal or coil resistance sensor. The sensor provides the drive's servo controller with the drive temperature. The current operating temperature of the disk drive, in combination with its modal sensitivity to thermal changes, are used to regularly update the servo controller. With this information, the servo controller calculates new butterfly mode characteristics as the operating temperature changes in order to actively compensate for the mode, and thus increase the performance of the disk drive.

Vibration mode compensation for disk drive

A method, apparatus, and article of manufacture for determining a transducer position in relation to a media surface is described. The method comprises sensing positioning information on the media, measuring a position error signal from the sensed positioning information wherein the position error signal includes first and second position signal components, accessing stored information describing a non-linear relationship between the measured position error signal and the transducer position, and applying the stored relationship to the measured position error signal to produce a corrected position error signal, and determining the transducer position from the corrected position error signal.

Position error signal linearization using an auxiliary discontinuity removal routine

A method, apparatus, and an article of manufacture for calibrating a position error signal for controlling the position of a read transducer with respect to a storage media having positioning information written at a location thereon. In one embodiment, the invention is embodied in a method comprising determining a relationship between a read transducer position and the positioning information by measuring the positioning information while passing the read transducer across the location, determining a measured position error signal from the measured positioning information, and computing a relationship between the measured position error signal and the read transducer position.

Position error signal calibration using measured bursts

An attachment structure and method for a disk drive apparatus for making the coupling resonance frequency of a hard disk drive the same whether one disk is loaded or a plurality of disks are loaded based upon parameters obtained from a simulation model. The modeling of a coupling vibration for one disk and for two disks is performed using a coupling vibration model of a linear two degree-of-freedom system. The component parts of a spindle motor providing a spring constant K,are adjusted so that the resonance frequency determined by coupling that of a spindle motor with that of the disk(s) is made much the same whether one disk or two disks are loaded. This adjustment enables stable track following to be secured without the need for adding dummy disks and other parts.

Disk drive apparatus, attachment structure, and attachment method

A disk drive system includes a servo system for driving mechanical parts, including a read/write head, to a desired track on a disk. The mechanical parts undesirably resonate at a frequency f, where f is a function of a temperature t of those mechanical parts. The servo system includes a notch filter responsive to an indication of temperature t, to attenuate the amplitude of frequency f in a broadband control signal that is applied to move the mechanical parts.

Servo system responsive to temperature changes

A method for writing circular track position information on a magnetic recording disk comprising the steps of (i) rotating the magnetic recording disk, and (ii) aerodynamically floating in a helium atmosphere a magnetic recording head adjacent to the disk and writing with the head circular track position information on the disk.

Method for writing servo information on a magnetic recording disk

A notch filter for a disk drive servo system is disclosed having selectable filtering capability. Different servo notch filters for different heads in the actuator head stack are provided. The notch filters may be selected to remove different resonant modes associated with the different disk drive heads. Each of the plurality of notch filters is tuned to remove a resonant frequency associated with at least one magnetic head of the disk drive. In operation, a notch filter is selected to remove a resonant frequency associated with a magnetic head commanded to write or read data to or from the disk drive. The notch filter system includes a multiplexor for controlling the selection of the notch filters. The multiplexor receives commands from a servo processor to control the selection of a notch filter. Different notch filters can be utilized, including series tapped notch filters or parallel notch filters. The notch filters are run continuously to avoid transients resulting from initialization of the notch filters.

Head selectable servo notch filter and method for improving servo system

An actuator assembly for a magnetic storage system wherein the end arms are dynamically tuned to reduce the modes of vibration on the actuator to improve the performance and stability of the actuator assembly in the magnetic storage system. In one embodiment, the upper and lower outer arms of the actuator assembly are thinned in the same or similar locations. In another embodiment, the upper and lower outer arms of the actuator assembly are notched at high strain energy points to reduce the stiffness of the outer arms. In still another embodiment, the upper and lower outer arms of the actuator assembly are both notched and thinned at the same or similar locations.

Dynamically tuned outer arms for improved rotary actuator performance

A spindle motor shaft having variable geometrical features for adjusting the torsion mode frequency of the shaft/stator assembly. The variable geometric features allow the torsion mode frequency to be tuned away from the driving force frequency of the motor. Variable geometrical features for the shaft may include circumferential grooves, radial slots cut through the shaft, or transverse holes disposed along the axis of the shaft. The radial slots have a longitudinal axis that is parallel to the axis of the shaft. Where circumferential grooves are used, the circumferential grooves may be designed to form a locator region along the shaft axis to promote axial alignment of the shaft and stator. Thermal track-misregistration (TMR) or screw torque problems are not introduced in the process of reducing or eliminating the acoustic problem thereby establishing a torsion mode frequency which is not subject to change due to temperature or time. Further, the removal of material from the shaft reduces the torsional stiffness of the shaft and lowers the torsion mode frequency of the shaft. Finally, the use of circumferential grooves prevents the wicking of excess epoxy up the shaft by the movement of the stator during the assembly/manufacturing process, which may lead to an undesirable increase in the stiffness.

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Los Altos, CA, United States of America

Gregory Michael Frees