Patents Assigned to Western Digital Corporation
  • Patent number: 6198584
    Abstract: A disk drive with a disk having a servo pattern including a special “calibration track” wherein a plurality of staggered calibration burst pairs define null points that are radially shifted from a burst pair centerline by precise, predefined, fractional track amounts to collectively provide accurate information about servo signal values generated as a function of real displacement. The staggered calibration bursts beneficially allows for calibrating the PES signal after the drive is removed from the servowriter during a manufacturing phase called Intelligent Burn-In. The staggered calibration bursts are preferably written in data regions so that they are disposable and may be selectively written over with data to maximize storage space. Some or all of the calibration bursts may alternatively be retained for a subsequent recalibration.
    Type: Grant
    Filed: April 30, 1998
    Date of Patent: March 6, 2001
    Assignee: Western Digital Corporation
    Inventors: Raffi Codilian, Ara W. Nazarian, Brian Tanner
  • Patent number: 6198590
    Abstract: A disk drive employs a method of operating a spindle motor to respond to a spin-down command to reduce the time required for subsequently responding to a spin-up command. After receiving the spin-down command, and while the rotor continues to spin in the forward-spin direction, a state machine is set to and maintained in a first predetermined register state such that a controlled rotor-stopping operation is performed. At the end of the controlled rotor-stopping operation, the rotor angle is within the range of a peaked forward direction waveform for a second predetermined register state of the state machine.
    Type: Grant
    Filed: July 21, 1998
    Date of Patent: March 6, 2001
    Assignee: Western Digital Corporation
    Inventors: Raffi Codilian, Terry C. Dawson, Carl R. Messenger, Steven Nemshick, Robert P. Ryan
  • Patent number: 6195218
    Abstract: A disk drive and method which efficiently stores zone parameter sets for a plurality of disk surfaces. The disk drive includes a disk control system and a plurality of disk surfaces. Each disk surface has an associated transducer head in communication with the disk control system for reading and writing data to the disk surface. Each disk surface is subdivided into a plurality of zones. Control parameters sets for each zone of a disk surface are stored in table. The disk drive further comprises a first disk surface and a second disk surface. A first zone parameter table is provided for the first disk surface. The first zone parameter table comprising a zone control parameter set for each zone of the first disk surface. A second zone parameter table is provided. The second zone parameter table includes a number of zone control parameter sets, wherein the zone control parameter sets and the second zone parameter table are not included in the first zone parameter table.
    Type: Grant
    Filed: June 25, 1998
    Date of Patent: February 27, 2001
    Assignee: Western Digital Corporation
    Inventors: James Edward Guttmann, Michael Scott Hicken, Timothy W. Swatosh
  • Patent number: 6195222
    Abstract: A disk drive and method of optimizing data access time by selecting a seek profile and/or settle criteria based on a queued or non-queued environment. The disk drive includes an actuator and a servo system, wherein the servo system is directed to move the actuator as a result of an input/output command received from a host by an interface processor. The disk drive may execute the input/output commands in a queued or non-queued environment. The servo system commands the actuator to perform a seek using a seek profile and defines settling criteria for the seek operation. The seek profile includes an acceleration profile and a deceleration profile. The method includes the step of providing a queued seek profile and a queued settling criteria for a seek used to position the actuator to execute a command in a queued environment.
    Type: Grant
    Filed: November 4, 1998
    Date of Patent: February 27, 2001
    Assignee: Western Digital Corporation
    Inventors: Mark D. Heminger, Eric G. Oettinger
  • Patent number: 6191909
    Abstract: A system for polling a preamplifier unit to remotely determine pre-established parametric values in a disk drive is disclosed. The disk drive comprises a controller, a preamplifier, and a plurality of transducers. The system for polling the preamplifier comprises means in the controller for generating a succession of serial bit characters each representative of a different pattern. A means is provided for successively transferring said serial bit characters from the controller to the preamplifier unit. A plurality of individual bit lines are provided in the preamplifier unit representative of at least one parametric value. A means is included in the preamplifier unit for comparing each serial bit pattern character received with said plurality of individual bit lines, and for generating a match signal when a serial bit pattern character received matches the plurality of individual bit lines. A means is provided for transferring the match signal from the preamplifier unit to the controller.
    Type: Grant
    Filed: June 13, 2000
    Date of Patent: February 20, 2001
    Assignee: Western Digital Corporation
    Inventors: Robert L. Cloke, David Price Turner, Robert Ellis Caddy, Jr., Michael Rodger Spaur
  • Patent number: 6185067
    Abstract: A spindle motor for a disk drive includes a shaft, an aluminum hub, a bearing, a magnetic steel back iron, and a magnet. The hub includes an axial wall having an inner surface. The back iron has an upper portion and a lower portion. The hub is concentrically position about the shaft such that the inner surface extends along a direction of a longitudinal axis defined by the hub. The bearing is positioned between the hub and the shaft. The back iron is secured to the hub such that the upper portion abuts the inner surface, whereas the lower portion is spaced-apart radially from the inner surface, thereby forming a single gap between the back iron and the hub. Finally, the magnet is attached to the back iron such that an axial length of the magnet is substantially coextensive with an axial length of the back iron.
    Type: Grant
    Filed: June 17, 1998
    Date of Patent: February 6, 2001
    Assignee: Western Digital Corporation
    Inventor: Stanley Case Chamberlain
  • Patent number: 6185074
    Abstract: A disk drive includes a disk drive base, a head stack assembly pivotally coupled to the disk drive base, a ramp load coupled to the disk drive base for parking the head, and an inertial latch. The head stack assembly includes a head and a coil portion coupled to the head, the coil portion defining an inner crash stop surface and an outer crash stop surface. The inertial latch includes a unitary latch base coupled to the disk drive base, an inner crash stop and an outer crash stop. The inner crash stop is integrally formed with the latch base and contacts the inner crash stop surface to limit travel of the head in a first direction during a shock event. The outer crash stop is also integrally formed with the latch base, and contacts the outer crash stop surface to limit travel of the head in a second direction during a shock event.
    Type: Grant
    Filed: December 29, 1998
    Date of Patent: February 6, 2001
    Assignee: Western Digital Corporation
    Inventors: David T. W. Wang, Shawn E. Casey
  • Patent number: 6181502
    Abstract: A disk drive includes a voice coil motor (VCM) and a VCM power source circuit which is coupled to a standard power supply having a fixed voltage. During seek operations the VCM power source circuit provides a boosted voltage, greater than the fixed supply voltage, for the VCM. The VCM power source circuit provides the boosted voltage independently from the back EMF generated in the voice coil motor. The increased VCM voltage allows faster access times and more efficient VCM operation.
    Type: Grant
    Filed: July 1, 1998
    Date of Patent: January 30, 2001
    Assignee: Western Digital Corporation
    Inventors: Hakam D. Hussein, Eric Gregory Oettinger, Michael C. Stich
  • Patent number: 6178056
    Abstract: A disk drive includes a disk surface having a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. The disk drive includes a read element operative during a user-data read operation for reading data from the disk surface to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive includes a sampled signal processing circuit that generates a servo state variable while processing the time-multiplexed read signal during the first servo time interval and a user data state variable while processing the time-multiplexed read signal during the first user data time interval.
    Type: Grant
    Filed: April 15, 1999
    Date of Patent: January 23, 2001
    Assignee: Western Digital Corporation
    Inventors: Robert Leslie Cloke, Richard W. Hull, Vafa James Rakshani, David Price Turner
  • Patent number: 6175893
    Abstract: A read-only memory is connectable to a microcontroller data bus and address bus and includes memory circuits for storing a sequential array of code words executable by the microcontroller; memory address decoding circuits for selecting one of the array of code words, and circuits for conveying the selected one to the data bus when a read signal is received from the microcontroller. Circuits are provided for storing an address transmitted by the microcontroller when an address latch signal is received from the microcontroller, the stored address being connected to the memory address decoding circuits. The stored address is incremented each time a read signal is asserted.
    Type: Grant
    Filed: April 24, 1998
    Date of Patent: January 16, 2001
    Assignee: Western Digital Corporation
    Inventors: Kenneth J. D'Souza, Tsun Yau Ng
  • Patent number: 6160368
    Abstract: A disk drive includes a spindle motor having windings and a spindle motor driver including switching elements connected to the windings. Spin-down instructions are stored in a memory. A microprocessor is responsive to a spin-down command to receive and execute the spin-down instructions. The execution of the spin-down instructions causes the microprocessor to perform the following pulsed braking sequence: (1) providing a brake signal for a first selected period of time (T1); (2) providing a coast signal for a second selected time period (T2); and (3) repeating (1) and (2). The spindle motor driver is responsive to the coast signal to control the switching elements to cause the spindle motor to coast and is responsive to the brake signal to control the switching elements to brake the spindle motor.
    Type: Grant
    Filed: June 22, 1998
    Date of Patent: December 12, 2000
    Assignee: Western Digital Corporation
    Inventor: Eugene F. Plutowski
  • Patent number: 6151189
    Abstract: A spindle motor for a disk drive includes a shaft, a stator, a hub, an upper bearing, a lower bearing, means for defining a gap and an ionization source. The stator is concentrically positioned about the shaft. The upper and lower bearings rotatably maintain the hub relative to the shaft and each include a plurality of balls, each ball made from a high resistivity material. The ionization source ionizes air in the gap for allowing static electric charge to dissipate through a conductive path provided by the ionized air in the gap.
    Type: Grant
    Filed: December 28, 1998
    Date of Patent: November 21, 2000
    Assignee: Western Digital Corporation
    Inventor: Peter E. Brooks
  • Patent number: 6151197
    Abstract: The disk includes a disk recording surface, and the ramp includes a ramp. A head stack assembly of a hard disk drive includes an actuator arm and a suspension assembly attached to the actuator arm. The suspension assembly includes a first elongated region having a distal region and a planar surface for facing toward the disk recording surface; the first elongated region defines a longitudinal axis. The suspension assembly includes a second elongated region positioned adjacent to the distal region. The second elongated region includes a lift tab for engaging the ramp surface and is vertically offset from the planar surface such that the lift tab is vertically displaced further from the disk recording surface than the planar surface. The second elongated region further includes a curved lift tab supporting member for supporting the lift tab and positioned between the distal region and the lift tab.
    Type: Grant
    Filed: December 30, 1998
    Date of Patent: November 21, 2000
    Assignee: Western Digital Corporation
    Inventors: Nils E. Larson, Scott E. Watson, Keith R. Berding
  • Patent number: 6147831
    Abstract: A servo track writer for a head disk assembly and a method of making the head disk assembly using the servo track writer are disclosed. The head disk assembly includes an enclosure having an opening and a base and an actuator arm coupled to the base and having a servo writer positioning arm facing surface. The servo track writer includes a platform for supporting the head disk assembly. The platform includes a base portion, a column extending substantially perpendicular to the base portion, and an elongated servo writer positioning arm for protruding through the opening and supported by the column. The positioning arm includes a main body, a tip having an actuator arm facing surface for abutting the positioning arm facing surface, and a vibration damper positioned between the main body and the tip. The vibration damper damps vibrations induced in the actuator arm by dissipating energy transferred between the platform and the actuator arm.
    Type: Grant
    Filed: June 18, 1998
    Date of Patent: November 14, 2000
    Assignee: Western Digital Corporation
    Inventors: Michael John Kennedy, James Benning, Martin J. McCaslin, Mark G. Dube
  • Patent number: 6145052
    Abstract: A method for selecting a next command to execute from a set of SCSI commands where the commands are gracefully aged and performance of a disk drive is improved. An execution threshold age, a pool threshold age, and an age threshold age are used to determine what command is executed next. A mechanical time delay is calculated for a command based on the time required to position the read/write head over the data location requested in each command. A command age is calculated based on a current time and the time the command was received from the host. The command age is checked against the execution threshold age and pool threshold age. Any commands that have aged beyond the execution threshold age are executed. If the oldest command has aged beyond the age threshold age, then any command that has both aged beyond the pool threshold age and has the smallest mechanical time delay is executed, otherwise the command with the smallest mechanical time delay is executed.
    Type: Grant
    Filed: November 4, 1997
    Date of Patent: November 7, 2000
    Assignee: Western Digital Corporation
    Inventors: Steven M. Howe, Jeffrey L. Williams
  • Patent number: 6141175
    Abstract: A method in a magnetic storage disk drive for independently learning and thereafter canceling repeatable runout that is written to the servo fields of each servo track during the servo writing process. The method does not require a servo writer because the disk drive may independently detect the runout without spinning out of control in response to such runout by operating its servo control loop in a low bandwidth mode so that it is less responsive to the higher frequency components of the runout, and by removing the effect of the DC component of the runout or selected harmonics on each revolution.The method takes several revolutions to "learn" the servo wedges of a current track by initializing a wedge runout value for each servo wedge and an average uncorrected runout value and then successively developing an interim wedge runout estimate for each servo wedge by adding a fractional portion .lambda. of a raw position error signal to a fractional portion (1-.lambda.
    Type: Grant
    Filed: October 8, 1997
    Date of Patent: October 31, 2000
    Assignee: Western Digital Corporation
    Inventors: Ara W. Nazarian, Charles W. Simmons, Thao P. Trieu, Richard K. Wong
  • Patent number: 6136403
    Abstract: A recording medium on a hard disk is provided that includes a magnetic data recording layer on the disk, a hydrogenated carbon buffer layer over the data recording layer, and a nitrogenated carbon overcoat layer over the hydrogenated carbon buffer layer. The composition ratios and thickness of the recording and nitrogenated carbon overcoat layers are suitably controlled to optimum ranges.
    Type: Grant
    Filed: July 24, 1998
    Date of Patent: October 24, 2000
    Assignee: Western Digital Corporation
    Inventors: Chanapatna Krishnamorthy Prabhakara, Amrik Singh Lehil, Stella Zofia Gornicki, Keith Samuel Goodson, Wing Tsang Tang
  • Patent number: 6122135
    Abstract: A method to adaptively reduce error introduced by the coil current rise time. A disk drive with a moving arm actuator driven by a voice coil motor is controlled by periodically modeling the coil current rise time. An adjustment to a commanded current value is based on the model of the coil current rise time and a magnitude change in commanded value. The model of the coil current is based on a linear approximation to the exponential rise time of the coil current. The commanded value is adjusted to compensate for the error in the control effort. For small commanded value differences no compensation is made for the coil current rise time. For medium command value differences a slope intercept equation is used to compute the compensated commanded value. For large commanded value differences half of an estimate of the maximum largest physical current change is used. The adjustment is made by the estimator in a position error signal feedback control system.
    Type: Grant
    Filed: December 19, 1997
    Date of Patent: September 19, 2000
    Assignee: Western Digital Corporation
    Inventor: Michael Charles Stich
  • Patent number: 6122133
    Abstract: A method used to implement a sampled servo control system in a magnetic disk drive for generating a fractional track portion of a position error signal to correctably maintain the alignment of a read transducer (or associated write transducer) relative to a centerline of one of a plurality of a concentric data tracks upon a rotating data storage disk. The system uses a hybrid approach of determining a fractional track position by using a two-burst algorithm when possible and using a multi-burst algorithm only when necessary. The system is particularly suited to determining fraction track position when jogging a relatively narrow magnetoresistive read transducer with a servo pattern normally useful only for wider transducers, namely a pattern of four angularly sequential servo bursts A, B, C, D that are 100% of a track pitch in width and are arranged in quadrature.
    Type: Grant
    Filed: June 17, 1998
    Date of Patent: September 19, 2000
    Assignee: Western Digital Corporation
    Inventors: Ara W. Nazarian, Brian Tanner, Richard K. Wong
  • Patent number: 6111717
    Abstract: A disk drive comprising a plurality of read/write transducers, a programmable preamplifier, and a controller for furnishing control and data signals to the programmable preamplifier and for receiving data signals therefrom, is disclosed. The programmable preamplifier comprising a write data input circuit for receiving data signals to be supplied to a transducer, a read data output circuit for manifesting data signals supplied to said preamplifier unit by a transducer, and a transducer interface circuit for providing write data signals to a transducer and receiving read data signals from a transducer.
    Type: Grant
    Filed: March 6, 1998
    Date of Patent: August 29, 2000
    Assignee: Western Digital Corporation
    Inventors: Robert L. Cloke, David Price Turner, Robert Ellis Caddy, Jr., Michael Rodger Spaur