Jason D Gregg

US Patent:

6347019, Feb 12, 2002

Filed:

Feb 22, 2000

Appl. No.:

09/510728

Inventors:

Jason D. Gregg - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5584

US Classification:

360 7804, 360 46

Abstract:

Apparatus and method for compensating for servo data distortion in a disc drive. During a seek wherein a head is moved from an initial track to a destination track on a disc surface, servo position data are decoded on intermediary tracks by generating nominally redundant positive and negative digital pulse streams from positive and negative peaks in a servo readback signal. The positive and negative digital pulse streams are combined using a default Boolean logical operator (such as an AND operator) to qualify pulses in a first output digital pulse stream used to determine head position. When distortion arises that prevents correct detection of head position from the first output digital pulse stream, a second Boolean logical operator (such as an OR operator) is switched in to generate a second output digital pulse stream. Depending on the type of distortion, a selected one of the operators will provide improved servo data decoding.

US Patent:

6392833, May 21, 2002

Filed:

Jul 13, 1999

Appl. No.:

09/352487

Inventors:

Roy L. Wood - Yukon OK
Jason D. Gregg - Oklahoma City OK

Assignee:

Seagate Technology, LLC - Scotts Valley CA

International Classification:

G11B 1546

US Classification:

360 7303, 360 69

Abstract:

Apparatus and method for improved operational performance of a disc drive by temporarily decreasing disc rotational velocity to reduce self-excited mechanical resonance established within the drive. The disc drive is first initialized by applying current to the spindle motor to accelerate the disc from rest to a nominal operational rotational velocity. Once initialized, the disc drive is operated in a normal mode, as the temperature of the drive increases from an initial, ambient temperature to an equilibrium temperature. During such operation, when the disc drive detects the presence of a self-excited mechanical resonance, the disc drive proceeds to temporarily decrease the rotational velocity of the disc to a reduced velocity to reduce the effects of the self-excited mechanical resonance. Thereafter, the rotational velocity of the disc is restored to the nominal velocity provided the self-excited mechanical resonance is no longer detected.

US Patent:

6445531, Sep 3, 2002

Filed:

Oct 8, 1999

Appl. No.:

09/415787

Inventors:

Mark A. Gaertner - Woodbury MN
Paul A. Galloway - Prior Lake MN
Bruce J. Routh - Eden Prairie MN
Zip Cotter - Eden Prairie MN
Daniel C. Kuhl - Saint Paul MN
Jason D. Gregg - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7806

Abstract:

A method of controlling an actuator in a disc drive to move a data head to implement an access in accordance with the invention includes determining a first rotational position corresponding to a rotational position of the data head when the access will start and determining a second rotational position corresponding to a rotational position of the data head at a destination of the access. Subsequently, an access time required to move the data head from the first rotational position on a current or initial track to the second rotational position on a destination track using a fastest of multiple seek profiles is determined. A slower or slowest of the multiple seek profiles which can be used to move the data head from the first track to the second track within the access time is determined. Subsequently, the actuator is controlled using the determined slower or slowest of the multiple seek profiles to implement the access. In addition, a disc drive is provided.

US Patent:

6453331, Sep 17, 2002

Filed:

Jul 30, 1999

Appl. No.:

09/364465

Inventors:

Matthew Chad Burton - Edmond OK
Jason Dale Gregg - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G06F 1710

US Classification:

708300

Abstract:

A method and system of filtering an unfiltered servo torque table of a disc drive where a plurality of data points are added to the beginning and end of the unfiltered servo table and the table is then shifted by a valve and then filtered.

US Patent:

6490120, Dec 3, 2002

Filed:

Jul 13, 1999

Appl. No.:

09/352461

Inventors:

Matthew C. Burton - Edmond OK
Jason D. Gregg - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7807, 360 7809

Abstract:

Apparatus and method for optimizing a gain of a disc drive servo circuit, the gain used to control the magnitude of current applied by the servo circuit to a voice coil motor to position a head adjacent tracks of a disc. The servo circuit includes a servo processor which selects an initial value of the gain, and then proceeds to perform a gain convergence operation wherein the head is repeatedly moved across the disc over a number of passes and position error is accumulated during each pass. The accumulated position error is used along with a scale factor to converge the gain from an initial gain value to a final, optimal gain value. The scale factor is variable and is also converged over the successive number of passes from an initial value to a final, nominal value, in order to decrease the time required to obtain the final, optimal gain value.

US Patent:

6574070, Jun 3, 2003

Filed:

Dec 21, 2001

Appl. No.:

10/034814

Inventors:

Jason D. Gregg - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7809

Abstract:

An apparatus and method optimizing a model reference generator of a servo circuit to substantially mimic actual read/write head positions are disclosed. The servo circuit includes a microprocessor with associated random access memory storing a current profile and a set of optimized filter coefficients. The coefficients optimize a delay length of a finite impulse response filter, which delays passage of the current profile to a double integrator embedded in the microprocessor. The double integrator generates the substantially mimicked head positions. The filter coefficients are optimized by first, generating a model reference trajectory vector with a length determined by a set of empirically determined filter coefficients, then seek in an open loop mode while applying the selected current profile to the servo circuit to determine an actual trajectory vector, and replacing the empirically determined filter coefficient with an optimized filter coefficient determined from a mathematical comparison of the vector trajectories.

US Patent:

6775090, Aug 10, 2004

Filed:

Oct 26, 2001

Appl. No.:

10/015144

Inventors:

James W. DuLaney - Oklahoma City OK
Jeffery D. Andress - Oklahoma City OK
Jason D. Gregg - Oklahoma City OK
Wonbo Shim - Edmond OK
Roy L. Wood - Yukon OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7702

Abstract:

Method and apparatus for improving data transfer rate performance of a disc drive data handling system having a plurality of transducing heads adjacent a corresponding plurality of data recording surfaces. Concentric tracks on each of the recording surfaces are provided with a physical track address determined by servo data written to each track. Logical track addresses are assigned to the tracks by positioning a first head adjacent a selected location on the corresponding recording surface, measuring a head offset value for each of the remaining heads, and assigning the logical track addresses on each data recording surface in relation to the measured head offset values. The logical cylinders include tracks with different physical track addresses, and the tracks in each logical cylinder are nominally aligned with the heads. This reduces the need for corrective seeks after head switching within the same logical cylinder.

US Patent:

6848019, Jan 25, 2005

Filed:

Oct 24, 2000

Appl. No.:

09/696269

Inventors:

Jack A. Mobley - Oklahoma City OK, US
Jason D. Gregg - Oklahoma City OK, US
Kenny T. Coker - Mustang OK, US
Leonard D. Doss - Oklahoma City OK, US

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G06F 1200

US Classification:

711111, 360 7801

Abstract:

Apparatus and method for improving disc drive performance by compensating for head-to-head offsets when scheduling a plurality of pending access commands. A disc drive includes a plurality of recording surfaces on which a plurality of concentric data tracks are defined. A servo circuit performs seeks to move a plurality of heads from an initial track to a destination track. A positional offset between each of the plurality of heads is measured and applied to an estimated seek length to calculate a corrected seek length. A corrected seek time is calculated from a seek profile table in relation to corrected seek length. The corrected seek time is used by a control processor to schedule the access commands stored in the memory.