Lan T Ngo

US Patent:

6937423, Aug 30, 2005

Filed:

Feb 6, 2004

Appl. No.:

10/773526

Inventors:

Lan V. Ngo - Garden Grove CA, US
Raffi Codilian - Irvine CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B005/596

US Classification:

360 7702, 360 7703, 360 7707

Abstract:

A method of reducing rotational vibration effects in a disk drive by sensing vibration in a sensor and generating corresponding sensor data; deriving a statistical sensor (SS) value based on the sensor data; deriving a statistical position error signal (SPES) value from servo sectors read by the head; comparing the SS value to a SS-threshold value; comparing SPES value to a SPES-threshold value; and generating a feed-forward command effort signal for reducing rotational vibration effects if the SS value exceeds the SS-threshold value and if SPES value exceeds the SPES-threshold value.

US Patent:

6952318, Oct 4, 2005

Filed:

Jan 30, 2004

Appl. No.:

10/769444

Inventors:

Lan V. Ngo - Garden Grove CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest

International Classification:

G11B019/02

US Classification:

360 69

Abstract:

A method for reducing the effects of rotational vibration in a disk drive comprising generating a self-induced vibration in the disk drive, and sensing the self-induced vibration in the first and second sensors and generating a corresponding first and second sensor data. The method further comprises comparing the first and second sensor data to determine a gain-differential, and scaling at least one of the first and second sensor data to reduce the gain-differential between the first and second sensors.

US Patent:

7023640, Apr 4, 2006

Filed:

May 27, 2004

Appl. No.:

10/856400

Inventors:

Raffi Codilian - Irvine CA, US
Lan V. Ngo - Garden Grove CA, US
Norman D. Gardner - Aliso Viejo CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 19/04
G11B 21/02
G11B 19/02

US Classification:

360 60, 360 69, 360 75

Abstract:

A disk drive comprising a first sensor mounted on a nominally stationary portion of the disk drive and adapted to detect acceleration disturbances of the disk drive. The disk drive further comprising: a dual-function subsystem having a first circuit adapted to provide a write-inhibit signal and a second circuit adapted to provide a feed-forward basis signal, the dual-function subsystem adapted to receive a first sensor signal from the first sensor and to provide (a) the write-inhibit signal based on the received first sensor signal and a first threshold value, and (b) the feed-forward basis signal based on the received first sensor signal.

US Patent:

6710966, Mar 23, 2004

Filed:

Oct 23, 2001

Appl. No.:

10/003943

Inventors:

Raffi Codilian - Irvine CA
Aswartha Narayana - Mission Viejo CA
Lan V. Ngo - Garden Grove CA

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5596

US Classification:

360 7708, 360 7702

Abstract:

The present invention may be embodied in a method, implemented in a disk drive, for adaptively reducing an effect of vibration during a track following operation. The disk drive includes a disk and a rotary actuator. The disk includes distributed position information in a plurality of servo wedges. The actuator carries a transducer and pivots on a base of the disk drive. The actuator may exhibit an imbalance that may be affected by a linear vibration. In the method, a sensor signal is generated that is responsive to a vibration to the disk drive. The sensor value is modified based on an adaptive-filter gain to generate a position error adjustment signal for modifying a nominal position error signal. The adaptive-filter gain is then altered based on an adjusted position error signal and the sensor value associated with the current servo wedge for use during a next servo wedge.