Lealon Ray Mckenzie

US Patent:

6414814, Jul 2, 2002

Filed:

Sep 23, 1999

Appl. No.:

09/401877

Inventors:

Lealon R. McKenzie - Edmond OK
Robert D. Murphy - Boulder CO

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7703, 360 40

Abstract:

A method for minimizing once per revolution (OPR) positional errors in a single disk servo track writer (STW) comprises clamping a disc having an outer edge in the servo track writer; spinning the disc in the servo track writer at a predetermined speed; measuring distance from the disc edge to a predetermined point to determine peak to peak once per revolution positional error; determining an average once per revolution positional error from the peak to peak once per revolution positional error; and setting a reference position for writing servo tracks on the disc equal to a predetermined track reference plus the average once per revolution positional error. The servo track writer apparatus comprises a spindle motor for supporting and rotating a disc and a distance sensor such as an interferometer mounted a preset distance from the edge of the disc for measuring the once per revolution outer diameter positional error.

US Patent:

6421199, Jul 16, 2002

Filed:

Sep 23, 1999

Appl. No.:

09/401895

Inventors:

Lealon R. McKenzie - Edmond OK
Robert D. Murphy - Boulder CO

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7704

Abstract:

A method for minimizing once per revolution (OPT) positional errors in a single disk servo track writer (STW) comprises clamping a disc in the servo track writer; spinning the disc at a predetermined speed; determining an average OPR positional error; and adjusting a reference position for writing servo tracks on the disc to include the average OPR positional error. The apparatus includes a distance measuring device positioned adjacent the disc in the STW. Another method for reducing the effects of OPR positional error in a disc drive comprises positioning a disc on a drive motor spindle in a disc drive during assembly of the drive; spinning the disc at a predetermined speed; determining the position of maximum peak to peak OPR position error, and then readjusting the position of the disc on the spindle to minimize the error. The apparatus for this method includes a controller, a distance sensor, and a positioner for nudging the disc to an optimum position on the disc drive spindle.

US Patent:

6538837, Mar 25, 2003

Filed:

Dec 30, 1999

Appl. No.:

09/475771

Inventors:

Lealon R. McKenzie - Edmond OK
Brian W. Sudman - Eden Prairie MN
Michael Baum - Longmont CO
Dennis D. Duffy - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 2102

US Classification:

360 75, 300 57

Abstract:

One embodiment of the present invention is directed to a method of aligning servo wedges of a plurality of disc surfaces in a disc drive. This process of aligning servo wedges in a disc drive includes writing multiple servo wedges, one adjacent another, continuously across an entire circumference of each disc surface. Subsequently, one of the disc surfaces is designated the master surface. Every n servo wedge on the master surface is then designated as a master wedge, where n is a positive integer. Next, the servo wedges on the non-master surfaces which are most closely axially aligned with the master wedges are selected. Subsequently, all of the non-selected and non-master wedges are erased.

US Patent:

6570733, May 27, 2003

Filed:

Apr 30, 1998

Appl. No.:

09/070580

Inventors:

David Charles Waugh - Oklahoma City OK
Lealon Ray McKenzie - Edmond OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7806, 360 7809

Abstract:

A method and apparatus are disclosed for improving seek performance of a disc drive through adaptive servo gain adjustment. The disc drive comprises a head adjacent a rotatable disc and a servo circuit which controllably positions the head adjacent tracks defined on the disc. During a seek operation in which the servo circuit moves the head from an initial track to a destination track, the servo circuit accumulates a velocity error as a sum of a series of velocity errors each obtained as a difference between an actual velocity of the head and a corresponding desired velocity over a selected radial distance of the disc. The servo circuit additionally measures an elapsed time for the head to pass over a second selected radial distance of the disc as the head is decelerated toward the destination track. Thereafter, the servo circuit adjusts a gain of the servo circuit in relation to the accumulated velocity error and the measured elapsed time.

US Patent:

6643080, Nov 4, 2003

Filed:

Jul 27, 2000

Appl. No.:

09/626029

Inventors:

Roy Lynn Wood - Oklahoma City OK
Lealon Ray McKenzie - Edmond OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 2736

US Classification:

360 31, 360 75, 360 7303

Abstract:

Method and apparatus for identifying a resonance by changing a spindle speed, which has the effect of changing a corresponding sampling rate and Nyquist frequency. The invention discriminates (1) between plausible frequencies of true resonance and/or (2) aliased resonance from non-aliased resonances. This is accomplished by monitoring whether and/or how a resonance shifts during this speed change. Methods of the present invention monitor resonances by deriving a resonance indicator such as an apparent frequency (below the Nyquist frequency), a gain or error magnitude (compared to a derived threshold at a calculated frequency of interest), or similar criteria tested by values conventionally illustrated on a Bode plot. The present invention further includes steps or structural features for configuring a controller to attenuate or similarly limit an unwanted frequency component of an actuator control signal. In this way, resonances in the actuator can be reduced, and servo speed and accuracy thereby enhanced.

US Patent:

7936532, May 3, 2011

Filed:

Oct 31, 2007

Appl. No.:

11/931623

Inventors:

Lealon Ray McKenzie - Shakopee MN, US
Steve M. Gaub - Longmont CO, US
Sandeep D. Sequeira - Johnstown CO, US
Matthew McLeod Chadsey - Mead CO, US

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 15/46

US Classification:

360 7303

Abstract:

Various embodiments relate to selectively inhibiting output from a transducer in response to the rate of change of acceleration that is experienced by the transducer. The rate of change of an acceleration signal, which is indicative of transducer's acceleration, is detected. Output of a signal through the transducer is selectively inhibited in response to the detected rate of change of the acceleration signal. A related apparatus can include a circuit that detects the rate of change of an acceleration signal and generates a transducer output inhibit signal in response to the detected rate of change of the acceleration signal. The transducer writes data on a recordable media. The accelerometer generates an acceleration signal that is indicative of transducer vibration. The circuit selectively inhibits writing of data through the transducer in response to a rate of change of the acceleration signal.

US Patent:

60881852, Jul 11, 2000

Filed:

Apr 5, 1999

Appl. No.:

9/286203

Inventors:

Ryan T. Ratliff - Oklahoma City OK
Roy L. Wood - Yukon OK
Lealon R. McKenzie - Edmond OK
Otis L. Funches - Oklahoma City OK

Assignee:

Seagate Technology, Inc. - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7703

Abstract:

An apparatus and method for detecting rotational vibration applied to a disc drive having a rotary actuator adjacent a rotatable disc. The actuator supports a head adjacent a recording surface of the disc and an actuator coil in a magnetic field of a magnetic circuit of a voice coil motor. A second, velocity sense coil is further coupled to the actuator and immersed in the magnetic field of the magnetic circuit, with the velocity sense coil being electrically isolated from the actuator coil. Rotational vibration is detected in relation to a sense voltage induced across the velocity sense coil as the magnetic circuit is moved relative to the velocity sense coil. A data transfer operation between the head and a host device is interrupted when the magnitude of the rotational vibration exceeds a specified magnitude. A servo circuit applies current to the actuator coil to position the head relative to the disc recording surface in relation to servo information transduced by the head, as well as in relation to the sensed voltage from the velocity sense coil.

US Patent:

57609900, Jun 2, 1998

Filed:

May 21, 1996

Appl. No.:

8/652323

Inventors:

Anish A. Ukani - Oklahoma City OK
Lealon R. McKenzie - Edmond OK
Daniel E. Hobson - Yukon OK

Assignee:

Seagate Technology, Inc. - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7704

Abstract:

A method for calibrating the position error signal in a servo system of a disc drive. The disc drive comprises a disc and an actuator adjacent the disc, the actuator including a head which is controllably positionable relative to data tracks on the surface of the disc using a servo position error signal generated using a scale factor generally indicative of the ratio of the width of the head to the width of the tracks on the disc. The head is positioned at the center of a selected track using an initial scale factor for the position error signal, the selected track having servo position fields comprising a plurality of burst patterns. The burst patterns include a first burst pattern extending radially from a first track boundary to a second track boundary of the selected track, a second burst pattern extending radially from the center of the selected track to the first track boundary and a third burst pattern extending radially from the center of the selected track to the second track boundary. At the center of the selected track, the magnitude of burst signals read by the head from the second and third burst patterns is nominally equal, and from this location the head is swept towards the first track boundary until the magnitude of burst signals from the second burst pattern is nominally equal to the magnitude of burst signals from the first burst pattern, identifying a quarter-track location halfway between the center of the selected track and the first track boundary. A calibration scale factor for the position error signal is determined from the ratio of the expected position error signal to the actual position error signal obtained at the quarter-track location.