Stuart K Francis

US Patent:

6754035, Jun 22, 2004

Filed:

Jan 31, 2001

Appl. No.:

09/773974

Inventors:

Stuart Kevin Francis - Oklahoma City OK
Mitchell Ray Rose - Edmond OK
Bijan Tehrani - Norman OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7806, 360 7804, 360 75, 360360002

Abstract:

The temperature of an actuator voice coil in a disc drive is regulated so as to prevent outgassing. In a preferred embodiment, coil temperature is calculated at the beginning of each long seek. If the temperature is determined to be at or below a predetermined âsafeâ level, temperature rise is not limited and power may be applied to the coil without additional limitations. If, however, coil temperature is determined to be above the âsafeâ level, proportional control is used to scale back power generation so as to prevent the coil temperature from exceeding the coils specified temperature limit.

US Patent:

7432677, Oct 7, 2008

Filed:

Dec 16, 2004

Appl. No.:

11/014348

Inventors:

Jeffrey A. Heydt - Longmont CO, US
David R. Street - Allen TX, US
Nicholas Swezey - Bartlesville OK, US
Stuart Kevin Francis - Oklahoma City OK, US

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

H02P 6/00

US Classification:

31840001, 318700, 318701, 31840013, 31840014

Abstract:

Method and apparatus for controlling a brushless dc motor, such as the type used in a data storage device to rotate data storage media. A sequence of drive pulses is applied to rotate the motor. The sequence is switched from first to second motor commutation states at a time determined in relation to changes in elapsed time between successive pulses in the sequence. Each drive pulse has a duration established in relation to an inductance of the motor, and is separated from adjacent pulses by an intermediate delay of predetermined value. A peak elapsed time interval between successive pulses is identified, and the next commutation state is switched in at a selected time after the peak time interval. The sequence preferably accelerates the motor from rest to an intermediate velocity, after which back electromotive force (bemf) commutation is used to accelerate the motor to a final operational velocity.

US Patent:

62855220, Sep 4, 2001

Filed:

Dec 18, 1998

Appl. No.:

9/215470

Inventors:

Lealon R. McKenzie - Edmond OK
D. Brent Douglas - Edmond OK
Nathaniel B. Wilson - Edmond OK
Stuart K. Francis - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 5596

US Classification:

360 7705

Abstract:

An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having first and second heads supported adjacent first and second disc recording surfaces, respectively. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of a readback signal generated from a circumferentially extending frequency pattern written to the first disc recording surface at a constant frequency. A servo circuit controllably positions the first and second heads in response to servo information stored on the second disc recording surface and the rotational velocity signal from the FM demodulator. The servo circuit further interrupts a data transfer operation between the second disc recording surface and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold.

US Patent:

60160438, Jan 18, 2000

Filed:

Jan 28, 1998

Appl. No.:

9/014756

Inventors:

Andrew R. Motzko - Burnsville MN
Garry E. Korbel - New Prague MN
John M. Baker - Tuttle OK
Stuart K. Francis - Oklahoma City OK

Assignee:

Seagate Technology, Inc. - Scotts Valley CA

International Classification:

G05B 102

US Classification:

318606

Abstract:

A motor control circuit controls a motor in a disc drive is provided. The motor control circuit includes a commutation circuit which provides commutation signals to the motor to commutate the motor at a commutation frequency. A frequency modulation circuit is operably coupled to the commutation circuit. The frequency modulation circuit provides a modulation signal which frequency modulates the commutation frequency according to a predetermined pattern.

US Patent:

63044064, Oct 16, 2001

Filed:

Dec 18, 1998

Appl. No.:

9/216326

Inventors:

D Brent Douglas - Edmond OK
Lealon R. McKenzie - Edmond OK
Nathaniel B. Wilson - Edmond OK
Stuart K. Francis - Oklahoma City OK
Arthur J. Clark - Oklahoma City OK

Assignee:

Seagate Technology LLC - Scotts Valley CA

International Classification:

G11B 1546

US Classification:

360 7303

Abstract:

An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having a base deck supporting a rotatable disc and an actuator having a moveable data head. A fixed head is supported over the disc at a predetermined radius and transduces a circumferentially extending frequency pattern written to the disc at a constant frequency to generate a readback signal. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of the readback signal. A servo circuit controllably positions the moveable data head in response to the rotational velocity signal and servo information readback by the moveable data head. The servo circuit interrupts a data transfer operation between the moveable data head and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold. The circumferentially extending frequency pattern is preferably used to clock the writing of the servo information during disc drive manufacturing.