David D Nguyen

US Patent:

6791785, Sep 14, 2004

Filed:

Feb 28, 2001

Appl. No.:

09/796920

Inventors:

Carl R. Messenger - Mission Viejo CA
David D. Nguyen - Fountain Valley CA

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 555

US Classification:

360 7804, 360 7809, 360 7807, 360 7806, 360 9702, 360 31, 318634, 318265, 318560, 318561

Abstract:

A controller for a disk drive that accesses a look up table having a plurality of thermally characterized values corresponding to a plurality of seek operations. For each seek operation, the corresponding value is added to a register. The controller decrements the register at a rate that is determined using servo interrupts occurring as a result of the rotation of the disk. When the value of the register exceeds a threshold, the controller adjusts the subsequent seek operation so as to inhibit damage to the voice coil as a result of overheating.

US Patent:

6885514, Apr 26, 2005

Filed:

Jul 31, 2001

Appl. No.:

09/920665

Inventors:

Raffi Codilian - Irvine CA, US
William D. Johns - Dana Point CA, US
Charles A. Park - Aromas CA, US
David D. Nguyen - Fountain Valley CA, US
Jack M Chue - Los Altos CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B027/36
G11B021/02

US Classification:

360 31, 360 75, 2960309

Abstract:

A method of manufacturing a disk drive and a disk drive made with such method where the width of the read element and the width of the write element are both measured at servo-writing time and the track pitch of the disk drive is set on the basis of those measurements. Disk drives with superior head width combinations are servo-written with a narrower track pitch in order to have a higher storage capacity. Disk drives with inferior head width combinations are detected before servo-writing so that the disk drive may be servo-written with wider track pitch rather than with a nominal track pitch that results in a subsequent drive failure during initial burn-in (IBI). The heads are used more efficiently in that heads that are more capable are used to their ability and less capable heads that would otherwise be disposed of are used at all. Fewer disk drives are required to be reworked and returned to the servo-writing process.

US Patent:

6967811, Nov 22, 2005

Filed:

Jul 2, 2004

Appl. No.:

10/884559

Inventors:

Raffi Codilian - Irvine CA, US
David D. Nguyen - Fountain Valley CA, US
Alexander Babinski - Aliso Viejo CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B005/596

US Classification:

360 7806

Abstract:

A disk drive comprising a first seek operating mode to move the actuator over a seek distance D in a seek time T, using a first seek profile for minimizing T, wherein for a first repetitive series of seeks over distance D a servo control system would require a delay time Tbetween seeks to control temperature rise in a VCM. A second seek operating mode to move the actuator over the seek distance D in a second seek time Tusing a second seek profile for limiting the temperature rise in the VCM, wherein for a second repetitive series of seeks over the seek distance D, a time average Tof the Tseek times is substantially less than T+T.

US Patent:

7035026, Apr 25, 2006

Filed:

Nov 1, 2004

Appl. No.:

10/978644

Inventors:

Raffi Codilian - Irvine CA, US
William D. Johns - Dana Point CA, US
Charles A. Park - Aromas CA, US
David D. Nguyen - Fountain Valley CA, US
Jack M. Chue - Los Altos CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 27/36
G11B 21/02

US Classification:

360 31, 360 75, 2960309

Abstract:

A method of manufacturing a disk drive and a disk drive where the width of the read element and the width of the write element are both measured at servo-writing time and the track pitch of the disk drive is set on the basis of those measurements. Disk drives with superior head width combinations are servo-written with a narrower track pitch in order to have a higher storage capacity. Disk drives with inferior head width combinations are detected before servo-writing so that the disk drive may be servo-written with wider track pitch rather than with a nominal track pitch that results in a subsequent drive failure during initial burn-in (IBI). The heads are used more efficiently in that heads that are more capable are used to their ability and less capable heads that would otherwise be disposed of are used at all.

US Patent:

7054098, May 30, 2006

Filed:

Jun 1, 2004

Appl. No.:

10/860339

Inventors:

Jie Yu - Irvine CA, US
David D. Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5/596

US Classification:

360 7806, 360 7804

Abstract:

A disk drive is disclosed comprising a disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor (VCM) for rotating the actuator arm about a pivot to actuate the head over the disk, wherein the VCM rotates the actuator arm into a latched positioned when the disk drive is idle. Disk drive control circuitry unlatches the actuator arm by applying a driving current to the VCM according to an open-loop current profile. The open-loop current profile comprises an acceleration pulse having an acceleration magnitude and an acceleration interval, and a deceleration pulse having a deceleration magnitude and a deceleration interval. The deceleration magnitude is substantially smaller than the acceleration magnitude, and the deceleration interval is substantially longer than the acceleration interval, to thereby attenuate acoustic noise when unlatching the actuator arm.

US Patent:

7064918, Jun 20, 2006

Filed:

Oct 31, 2003

Appl. No.:

10/698273

Inventors:

Raffi Codilian - Irvine CA, US
David D. Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 21/02

US Classification:

360 75

Abstract:

A method for reducing a servo channel head gain calibration time comprising initiating a servo channel head gain calibration process for a head corresponding to the selected disk surface; obtaining a head gain calibration value for a pre-selected zone in the selected disk surface; comparing the obtained calibration value with a pre-stored calibration value for the pre-selected zone and generating a comparison result; and stopping the calibration process for the head if the comparison result does not exceed a threshold value.

US Patent:

7110208, Sep 19, 2006

Filed:

Jul 30, 2004

Appl. No.:

10/903524

Inventors:

Masao Miyamura - Diamond Bar CA, US
David D. Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5/596
G11B 5/09

US Classification:

360 7708, 360 48

Abstract:

A method is disclosed for improving servo performance in a disk drive having a plurality of concentric tracks. Each track has a plurality of first-type servo sectors and a plurality of second-type servo sectors. In the method, track identification information and track position information are read from a first-type servo sector. A track number and a transducer position are estimated for a second-type servo sector. Track position information is read from the immediately following second-type servo sector. An odd/even property from the second-type servo sector is compared with an odd/even property for the estimated track number. The odd/even property of the estimated track number is conditionally adjusted such that the odd/even property of the estimated track number matches the odd/even property from the second-type servo sector. A position error signal is determined using the adjusted track number and the track position information read from the second-type servo sector.

US Patent:

7253582, Aug 7, 2007

Filed:

May 28, 2004

Appl. No.:

10/856320

Inventors:

Jianghong Ding - Lake Forest CA, US
Chuanwen Ji - Irvine CA, US
David D. Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G05B 1/06

US Classification:

318652, 318273, 318259, 360 7303, 360 741

Abstract:

A disk drive is disclosed comprising a spindle motor having a plurality of windings including at least a first winding, a second winding, and a third winding. During a spin-up operation, a voltage is applied to the first winding and a first rise time is measured for current flowing through the first winding to reach a predetermined threshold. A voltage is applied to the second winding and a second rise time is measured for current flowing through the second winding to reach a predetermined threshold. A voltage is applied to the third winding and a third rise time is measured for current flowing through the third winding to reach a predetermined threshold. A difference is computed in response to the first rise time, the second rise time, and the third rise time, and an angular position of the spindle motor is estimated by computing an arctangent in response to the difference.