Abstract: A hard disk drive comprising an actuator control system that measures the temperature of an actuator coil and methods for providing the same. The control system comprises a controller and a current source controlled by the controller that generates a flow of current through the actuator so as to reposition a transducer of the drive. The control system further comprises sampling means for sampling at least one electrical characteristic of a conducting path defined by the coil. The control system measures the temperature by monitoring the current flowing through the coil and/or the voltage across the coil and by extracting the coil temperature from the monitored values. In one embodiment, the control system obtains a measurement of the coil by successively approximating the resistance of the coil until an estimated back emf component of the voltage across the coil.

Abstract: A disk drive and methods for preventing a coil in a voice coil motor from overheating due to the application of excess current. The disk drive comprises a servo control system. The servo control system is adapted for applying a current to a coil of the voice coil motor thereby causing the voice coil motor to move the head according to a seek distance. The servo control system generates a plurality of seek profiles for each of a plurality of seek distances and a plurality of current limits for the plurality of seek profiles. Each of the plurality of seek profiles defines a plan for controlling the current to be applied to the coil while the voice coil motor is operated over the seek distance. The plurality of current limits each define a maximum current allowed while controlling the current to be applied to the coil.

Abstract: A method of manufacturing a disk drive where the width of the read element is measured at servo-writing time in order to establish a write unsafe (WUS) limit corresponding to a maximum distance during writing that the write element is permitted to move radially offtrack from the centerline of a data track before writing is disabled. The method includes the steps of measuring a width of the read element with a servo track writer and determining a write unsafe (WUS) limit based on the data track pitch and the measured width of the read element. Varying the WUS limit on a drive-by-drive basis enhances the performance of some drives that would otherwise have capability that goes unused.

Abstract: The invention relates to a technique for shock estimation and write termination control in a disk drive. During a data write operation, a selected track's embedded servo sectors are read to generate position error signal values. A write unsafe limit is provided for terminating a data write operation if at least one position error signal value exceeds the write unsafe limit. A shock event limit is provided, and if a current position error signal value is less than the write unsafe limit value, then a function value is calculated based on the current position error signal value and a previous position error signal value. If the calculated function value exceeds the shock event limit, a data write operation is terminated. Otherwise, the operation is continued.

Abstract: The present invention may be embodied in a method, implemented in a disk drive, for adaptively reducing an effect of vibration during a track following operation. The disk drive includes a disk and a rotary actuator. The disk includes distributed position information in a plurality of servo wedges. The actuator carries a transducer and pivots on a base of the disk drive. The actuator may exhibit an imbalance that may be affected by a linear vibration. In the method, a sensor signal is generated that is responsive to a vibration to the disk drive. The sensor value is modified based on an adaptive-filter gain to generate a position error adjustment signal for modifying a nominal position error signal. The adaptive-filter gain is then altered based on an adjusted position error signal and the sensor value associated with the current servo wedge for use during a next servo wedge.

Abstract: An aspect of the invention can be regarded as a disk drive that includes a disk drive base and a spindle motor hub rotatably coupled to the disk drive base. The disk drive further includes a first disk disposed about the spindle motor hub. The disk drive further includes a second disk disposed about the spindle motor hub. The disk drive further includes a first disk spacer disposed between and in mechanical communication with the first and second disks. The first disk spacer has a first disk spacer first side disposed adjacent the first disk and an opposing first disk spacer second side disposed adjacent the second disk. The first disk spacer first side is defined by a first disk spacer first surface pattern. The first disk spacer second side is defined by a first disk spacer second surface pattern different than the first disk spacer first surface pattern.

Abstract: A spindle motor for use in a disk drive has a spindle motor hub having an axis of rotation, an annular magnet element coupled to the spindle motor hub, and a spindle motor stator. The spindle motor stator includes a stator rim formed of a plurality of laminate layers concentrically disposed about the axis of rotation. The stator rim has a plurality of stator teeth portions in operable communication with the magnet element for rotating the spindle motor hub. The stator teeth portions each have a magnetic flux surface disposed orthogonal to the axis of rotation. The spindle motor stator has a plurality of windings distributed along the stator rim. The windings each have a winding axis parallel to the axis of rotation and being disposed about respective ones of the stator teeth.

Abstract: The present invention may be embodied in a method, and related apparatus, for determining a repeatable runout (RRO) compensation value sets for a plurality of tracks on a disk in a disk drive, wherein the disk drive is initially manufactured and then shipped for installation in a host system. Each track comprises a plurality of embedded servo sectors that define a circumferential path that may have RRO requiring compensation during track following. The method comprises determining first RRO value sets for a first portion of the tracks to a first desired learning level by measuring the RRO for the first portion tracks based on a first predetermined number of disk rotations during the initial manufacturing of the disk drive. The first portion tracks are not adjacent to each other.

Abstract: A disk drive is disclosed comprising a head disk assembly (HDA) including an enclosure for housing a disk and a head actuated radially over the disk. A printed circuit board assembly (PCBA) is attached to the HDA enclosure, wherein the PCBA comprises at least one attached electrical component. A non-electrically conductive coating is bonded to at least part of the PCBA after attaching the electrical component to the PCBA.

Abstract: An aspect of the invention can be regarded as a disk drive that includes a disk drive base and a spindle motor hub. The disk drive includes a disk disposed about the spindle motor hub and including a disk surface. The disk drive includes a plurality of fasteners. The disk drive includes a disk clamp attached to the spindle motor hub in mechanical communication with the disk surface for securing the disk. The disk clamp includes a plurality of engaged fastener holes formed through the disk clamp and non-symmetrically distributed about an axis of rotation. The fasteners are engaged within the engaged fastener holes for attachment of the disk clamp and the disk to the spindle motor hub. According to another aspect of the present invention, fasteners are non-uniformly torqued within fastener openings for applying a non-symmetric clamping force by the disk clamp against the disk.

Abstract: A disk drive that includes a base, a magnetic disk, a rotary actuator that carries a head for reading and writing data from the disk in a track-following mode under the control of a servo control system, and at least two sensors—one fixed sensor rigidly coupled to the overall disk drive and one mobile sensor mounted to the rotating actuator—for differentially detecting accelerations of the rotary actuator relative to the overall disk drive and its disk. The disk drive detects and actively compensates for accelerations imparted to a balanced actuator that has an effective imbalance. The fixed sensor is preferably mounted to a PCBA that is secured to the base. The mobile sensor is preferably mounted to an actuator arm of the rotary actuator, as far outboard as possible, and so as to align with the fixed sensor as the rotary actuator swings through its range of travel. The preferred sensors are linear accelerometers.

Abstract: The invention may be embodied in a disk drive for use in a mobile device. The mobile device may be a hand held computing device such as a personal digital assistant (PDA) or a mobile terminal such as a cellular telephone. The mobile device includes a host processor for accessing data on the disk drive. The disk drive has a rotating disk media and a moveable read/write head disposed over the disk media. The disk media is divided into a first data storage zone and a second data storage zone. The data storage zones are radially disposed in discrete areas of the disk media and each zone has a plurality of tracks for storing data. The mobile device may write data to the first data storage zone when the mobile device is in a mobile environment. The mobile device may write data to the second data storage zone only when the mobile device is in a non-mobile environment and may not write data to the second data storage zone when the mobile device is in a mobile environment.

Abstract: A servo system in a disk drive in a mobile device is responsive to an environment signal from the mobile device to generate a first current profile to a head actuator when the mobile device is docked and to generate a second current profile to the head actuator when the mobile device is mobile. The second current profile requires less power than the first current profile, thus reducing current drain on a battery in the mobile device.

Abstract: The invention may be embodied in a disk drive for use in a mobile device. The mobile device may be a hand held computing device such as a personal digital assistant (PDA) or a mobile terminal such as a cellular telephone. The mobile device includes a host processor for accessing data on the disk drive. The disk drive has a rotating disk media surface and a moveable read/write head disposed over the media surface. The disk drive includes a first data storage zone on the disk media surface for storing data on first data tracks using a first track pitch, and a second data storage zone on the common disk media surface for storing data on second data tracks using a second data track pitch. The first data track pitch is substantially wider than the second data track pitch.

Abstract: A disk drive with a plant having an actual plant response G(z) and a servo controller that includes a feed-forward control path that operates with a modeled plant response G0(z) in order to output a feed-forward command effort. The plant includes a transducer that is moveable from a start position to a target position according to a total control effort.

Abstract: A spindle motor for use in a disk drive has a spindle motor hub having an axis of rotation, an annular magnet element coupled to the spindle motor hub, and a spindle motor stator. The spindle motor stator has a stator rim formed of a plurality of adjacent arc segments. The arc segments each respectively has opposing curved ends extending parallel to the axis of rotation. The curved ends of respective adjacent arc segments cooperatively form a plurality of stator teeth in operable communication with the magnet element for rotating the spindle motor hub. The spindle motor stator has a plurality of windings distributed along the stator rim. The windings each have a winding axis parallel to the axis of rotation and being disposed about respective ones of the stator teeth.

Abstract: A mobile device is disclosed comprising a disk storage system comprising a disk and a head actuated over the disk, the disk comprising a data area. The mobile device further comprises a pressure-sensitive detector for detecting a pressure on the mobile device, and for detecting a decrease in the pressure on the mobile device indicating the mobile device may have been dropped. When the pressure-sensitive detector detects the decrease in the pressure, retracting circuitry within the mobile device retracts the head to a retracted position away from the data area of the disk.

Abstract: A population of disk drives includes a first disk drive configuration that has a spindle motor made according to the spindle motor design and a second disk drive configuration that has a spindle motor made according to the spindle motor design. A population of spindle motors are manufactured according to a spindle motor design. Each of the spindle motors in the population of spindle motors has a track-following characteristic in a range. A first group of spindle motors that correspond to a first portion of the range are allocated to the first disk drive configuration. A second group of spindle motors that correspond to the second portion of the range are allocated either to the second disk drive configuration or to the first disk drive configuration.

Abstract: An aspect of the invention can be regarded as a method of balancing a rotary actuator for use in a rotatable head stack assembly (HSA) portion in a disk drive. The rotary actuator has a pivot axis, and the rotatable HSA portion has an installed HSA portion center-of-gravity. The method provides for determining a desired rotary actuator center-of-gravity location for locating the installed HSA portion center-of-gravity along the pivot axis for mitigating acceleration of the rotary actuator about the pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation. The method further provides for measuring weight distribution characteristics of the rotary actuator to determine an actual rotary actuator center-of-gravity. The method further provides for selectively modifying weight distribution characteristics of the rotary actuator to locate the actual rotary actuator center-of-gravity at the desired rotary actuator center-of-gravity location.

Abstract: The present invention may be embodied in a method, and related apparatus, for determining a repeatable runout (RRO) compensation value set for a track on a disk in a disk drive, wherein the disk drive is initially manufactured and then shipped for installation in a host system. The track comprises a plurality of embedded servo sectors that define a circumferential path having RRO which requires compensation during track following. The method comprises determining a first RRO compensation value set for the track to a first desired learning level by measuring the RRO for the track based on a first predetermined number of disk rotations during the initial manufacturing of the disk drive.