Castlewood Systems, Inc.

Syquest Technology, Inc.

Headway Technologies, Incorporated

Riospring, Inc.

Castlewod Systems, Inc.

David M Drouin

Vien N Nguyen

Stephen R Jackson

Frank Ivan Morris

Sung Soo Chung

David Hu

Ich V Pham

Avraham Perahia

Billy Wahng

Li-Hsin Lu

Evelyn Howard

Howard Steinhoff

The resonance frequency of a forced torsionally oscillating mirror MEMS device can be controlled in the presence of perturbations by means of a closed loop feedback device and method of using it. The method is implemented through a simple algorithm, implemented in either software or hardware, that maintains the condition of resonance, or another selected frequency, by recursively determining that the center of the driving voltage pulse is positioned at a point on the measured positional waveform of the oscillating system.

Drive method for starting and operating a resonant scanning MEMS device at its resonant frequency

A magnetic hard disk drive includes a method for eliminating that portion of track following error by a read/write transducer that is caused by repeatable runout of the disk tracks. The repeatable runout is eliminated by application of an iterative algorithm that calculates feed-forward correction terms based on gain coefficients iteratively calculated from the amplitude and phase portions of a Bode plot characterizing the system. The corrective coefficients can be inserted into the hard disk drive at a summing junction that redefines the centerline of the track, or at a summing junction that causes the actuator to follow the repeatable runout and make non-repeatable runout corrections relative thereto.

Feed-forward method for repeatable runout cancellation

One embodiment of the present invention is an apparatus to provide a measure of disk drive head velocity in a disk drive wherein movement is produced by a disk drive motion mechanism that includes a coil, which apparatus includes: (a) a controller that outputs one or more digital signals that are applied as input to a first component, and in response, the first component outputs a reference voltage; (b) a second component, responsive to voltage output across the coil and the reference voltage, outputs a measure of a difference between the coil voltage and the reference voltage; and (c) a third component, responsive to the measure of the difference, outputs a first value if the coil voltage is greater than the reference voltage and a second value if the coil voltage is less than the reference voltage, which third component output is applied as input to the controller; wherein the controller executes a search algorithm that varies the one or more digital signals while observing changes in the third component output to provide a digital estimate of the coil voltage, which estimate provides a measure of the disk drive head velocity.

Method and apparatus to measure disk drive head load/unload velocity

A method of writing data to multiple disks on a servo track writing machine comprises the steps of providing a cylindrical disk stacking tool comprising a base and a spindle, loading a first disk onto the spindle in alignment with the base, loading a second disk onto said spindle in alignment with the first disk, placing the loaded disk stacking tool on the servo track writing machine, and simultaneously writing data to the disks with the servo track writing machine. As many disks as desired may be so written to. The disk stacking tool further includes a clamp for locking the disks in place.

Multiple disk write method and device

A system having a storage device including read/write heads for repositioning the read/write heads from a parking location to a position adjacent a surface of a magnetic disk, the storage device includes a spindle motor coupled to the magnetic disk, for accelerating the magnetic disk to at least a first number of revolutions per time period while the read/write heads are positioned at the parking location, and a solenoid control coupled to the read/write heads and to the spindle motor, for biasing the read/write heads towards the position adjacent the surface of the magnetic disk after the magnetic disk reaches the first number of revolutions per time period, wherein the spindle motor maintains a rotation of the magnetic disk at less than a second number of revolutions per time period before the read/write heads are positioned adjacent the surface of the magnetic disk, and wherein the spindle motor rotates the magnetic disk at a third number of revolutions per time period after the read/write heads are positioned adjacent the surface of the magnetic disk.

Disk speed profile method and device

A technique for formatting a magnetic disk for a removable magnetic cartridge includes the steps of providing the magnetic disk having a top surface and a bottom surface, writing a first servo track onto the top surface, the first servo track having a portion including a first gray code, a first position burst, and a second position burst, writing a second servo track onto the top surface adjacent to the first servo track, the second servo track having a portion including a second gray code, the second position burst, and a third position burst, and writing a third servo track onto the top surface adjacent to the second servo track, the third servo track having a portion including the second gray code, the third position burst and a fourth position burst, wherein a first data track comprises the first servo track, the second servo track and the third servo track.

Burst pattern for detecting the position of a read/write head relative to a magnetic disk

A technique for reading data from a magnetic disk includes the steps of providing the magnetic disk including a cylinder having a plurality servo sectors, a plurality of data sectors, and a zone data table, the plurality of servo sectors including a first servo sector, a second servo sector, a third servo sector, a fourth servo sector, and a fifth servo sector, the zone data table including at least a nominal timing latency between the fourth servo sector and a data sector from the plurality of servo sectors, reading the first servo sector, the second servo sector, the third servo sector, and the fourth servo sector from the magnetic disk, determining a first timing deviation for the first servo sector between the first servo sector and the second servo sector, determining a second timing deviation for the second servo sector between the second servo sector and the third servo sector, predicting a predicted third timing deviation for the fourth servo sector between the fourth servo sector and the fifth servo sector, in response to the first timing deviation and to the second timing deviation, modifying the nominal timing latency in response to the predicted third timing deviation to form a predicted timing latency, and waiting the predicted timing latency after reading the fourth servo sector before reading the data sector.

Data sector timing compensation technique based upon drive eccentricity

A technique for determining a position of a read/write head relative to a magnetic disk includes the steps of providing the magnetic disk having a plurality of odd servo sectors and a plurality of even servo sectors, reading a first gray code pattern in an odd servo sector from the plurality of odd servo sectors on the magnetic disk, reading a second gray code pattern in an even servo sector from the plurality of even servo sectors on the magnetic disk, the even servo sector adjacent to the odd servo sector on the magnetic disk and determining the position of the read/write head only in response to the first gray code pattern and the second gray code pattern.

Servo-burst gray code pattern

A technique for method for positioning a magneto resistive head located upon an actuator arm onto a loading ramp of a storage unit. The technique includes the steps of operating a removable magnetic disk at a first number of revolutions per second, the magnetic disk having an outer diameter, positioning the magneto resistive head adjacent to the removable magnetic disk, reading data from the removable magnetic disk, detecting a reset signal, producing a back electro-motive force in response to the reset signal, biasing the magneto resistive head towards the outer diameter of the removable magnetic disk in response to the reset signal and to the back electro-motive force, reducing a number of revolutions per second for the removable magnetic disk from the first number to a second number of revolutions per second, the first number greater than the second number; thereafter using an energy storage unit to bias the magneto resistive head onto the loading ramp, in response to the reset signal.

Power-off method and device for electronic storage apparatus

A method for applying an optimal seeking technique to a disk file with excessive repeatable runout includes a method of modifying a control signal for a rotary actuator arm of a disk drive. The control signal is modified during track seeking by adding a runout state that is calculated each time a servo sector of a target data track on a surface of a disk is sampled by read/write heads carried by the actuator arm. A calibration algorithm can be used during track following to determine runout magnitude and runout phase at various preselected calibration tracks on the surface of the disk. A seeking algorithm can be implemented to compensate for the relative runout magnitude and phase variations between present and target tracks.

Method for applying optimal seeking technique to disk file with

A method for applying an adaptive feed-forward waveform correction to a primary servo loop compensation signal in a rotating data storage apparatus. A position error signal is used to determine a fixed feed-forward correction upon initialization or other predetermined conditions. An adaptive feed-forward waveform correction is periodically determined by adding a scaled version of the position error signal to the stored adaptive feed-forward value, and then processing the resulting sum through a frequency selective filter. The stored adaptive feed-forward correction is then updated with this new result. Simultaneously, the updated adaptive feed-forward correction is combined with the fixed feed-forward correction and the position error signal to generate a primary servo loop compensation signal for controlling the read/write head of the data storage apparatus.

Applying an adaptive feed-forward algorithm as a frequency selective

A disk drive employing a voice coil actuator to position a read/write head over a magnetic disk retracts the read/write head from the magnetic disk surface and passes an audio frequency alternating current through the voice coil to produce a corresponding movement in the read/write head support structure which generates an audible tone indicating the disk drive status. The alternating current waveform has a positive phase and a negative phase, with the read/write head moving toward the disk in response to one phase of the current and the read/write head moving away from the disk in response to the other phase. Audible tones of different frequencies are produced by varying the frequency of the alternating current waveform. In this fashion the disk drive generates a predetermined sequence of tones separated by silent pauses which identifies a particular disk drive status condition.

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Fremont, CA, United States of America

David M Drouin