David Weiming Tien

US Patent:

6995941, Feb 7, 2006

Filed:

Jan 7, 2005

Appl. No.:

11/031616

Inventors:

Masao Miyamura - Diamond Bar CA, US
David Dung Tien 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 is disclosed for improving head position determination in a disk drive having a transducer head and a rotating disk with a plurality of embedded servo wedges for defining a plurality of concentric data tracks. Each servo wedge has a plurality of servo bursts for providing radial track position information. In the method, the servo bursts within a servo wedge are read and a burst amplitude is determined for each servo burst. The burst amplitudes are compared to determine a radial servo position zone. A fine radial head position within the radial servo position zone is determined based on a ratio having a numerator consisting of an algebraic sum and difference of the burst amplitudes and a denominator consisting of an algebraic difference between a largest burst amplitude and a smallest burst amplitude.

US Patent:

7110214, Sep 19, 2006

Filed:

Jan 18, 2005

Appl. No.:

11/039401

Inventors:

Kuang-Yang Tu - Irvine CA, US
David Dung Tien Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5/596

US Classification:

360 7806

Abstract:

Disclosed is a disk drive including an actuator having a coil, a head attached to the actuator, and a disk including at least a first track and a second track, and a processor for controlling operations in the disk drive including a seek operation from the first track to the second track in which the head is moved between the first track and the second track by the movement of the actuator. The processor under the control of a program generates a deceleration velocity profile for the seek operation that is determined based upon a deceleration velocity profile function that includes a back electromagnetic force (BEMF) model to take into account back electromagnetic forces (BEMFs) associated with the coil of the actuator such that the BEMFs are mathematically modeled. The head is commanded to seek to the second track utilizing the deceleration velocity profile function that includes the BEMF model.

US Patent:

60142839, Jan 11, 2000

Filed:

May 15, 1997

Appl. No.:

8/856670

Inventors:

Raffi Codilian - San Dimas CA
Ara W. Nazarian - Tustin CA
David Dung Tien Nguyen - Fountain Valley CA

Assignee:

Western Digital Corporation - Irvine CA

International Classification:

G11B 5596

US Classification:

360 7708

Abstract:

A magnetic storage disk drive having a servo burst pattern which asymmetrically increases the linear region in which a read head may be micro-jogged from a burst pair center line to align the read head with a data track. The innovative servo pattern comprises a first pair of servo bursts that define a first burst pair centerline for writing a particular data track to a data track side of the first centerline, and a second pair of servo bursts collectively define a second burst pair centerline that is positioned to the data track side of the first burst pair centerline and is sufficiently close to the first burst pair center line so that the read head "sees" the second pair of servo bursts before "losing" the first pair of servo bursts when micro-jogged to the data track side for reading. The second burst pair centerline should be no farther from the first burst pair centerline than the linear read width of the read head. The preferred servo bursts span a full track pitch are arranged in a uniformly repeating pattern of A/B and C/D burst pairs.

US Patent:

57935580, Aug 11, 1998

Filed:

Jun 5, 1996

Appl. No.:

8/658345

Inventors:

Raffi Codilian - San Dimas CA
David Dung Tien Nguyen - Fountain Valley CA

Assignee:

Western Digital Corporation - Irvine CA

International Classification:

G11B 5596

US Classification:

360 7806

Abstract:

A method and system for a disk drive that estimates demand DAC saturation current by performing a first slew with the demand DAC in saturation, and then iteratively refining the estimate in response to a sequence of slews with the demand DAC not in saturation. Each successive slew is performed with the demand DAC preloaded with an acceleration value calculated in the previous iteration. To perform each slew, the disk drive microcontroller loads the demand DAC with an acceleration value, waits a predetermined time interval, and reads servo signals to identify the track to which the head has slewed at the end of the time interval. The microcontroller then calculates the distance traveled by the actuator during the present slew and uses the ratio of this head travel distance to the head travel distance of the first (saturated) slew to refine the saturated acceleration value estimated in the previous iteration. These estimates converge over successive iterations toward the desired demand DAC saturation current.