Hang Thi Ngo

US Patent:

6567240, May 20, 2003

Filed:

Feb 26, 2001

Appl. No.:

09/793236

Inventors:

Bradley Frederick Baumgartner - Los Banos CA
Andrew John Buhler - San Jose CA
Erich Chuh - San Mateo CA
Hang Fai Ngo - San Jose CA
Bob C. Robinson - Hollister CA
Elmer Tyree York - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 582

US Classification:

360135

Abstract:

A disk for a disk drive uses a circular platter having first and second sides and a circumferential edge. The circumferential edge of the disk has four symmetrically spaced apart shadows and a fifth or additional shadow that gives the disk an asymmetrical shadow signature. The fifth shadow is offset relative to the other shadows, which have congruent arcuate lengths and separation. The fifth shadow has an arcuate length that is about half as long as those of the other shadows, and is closely spaced adjacent to one of the other shadows. The asymmetric shadow signatures of the disk is used to precisely determine both the circumferential position of the platters and their planar orientation (i. e. , A-side or B-side). For example, when the disk is mounted on a tool spindle and rotated, an optical detector detects the pattern of the shadows and feeds the data to a computer system.

US Patent:

6662623, Dec 16, 2003

Filed:

Sep 20, 2001

Appl. No.:

09/957291

Inventors:

Bradley Frederick Baumgartner - Los Banos CA
James Hammond Brannon - Palo Alto CA
Jorge Daniel Colonia - San Jose CA
Huyen D. Do - San Jose CA
Shanlin Duan - Fremont CA
Connie H. Moy - San Jose CA
Hang Fai Ngo - San Jose CA
Yu Lo - Fremont CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 582

US Classification:

73 189

Abstract:

A disk for calibrating glide heads utilizes a dual-zone configuration of multiple laser melt bumps having selected heights. Averaging the PZT response over many bumps significantly narrows the response distribution, resulting in greater certainty and correlation of the PZT amplitude to bump height. The multiple calibration bumps are circumferentially arranged on a disk surface at a selected radius in a ring-like manner. A second head cleaning zone is provided near the inner diameter of the disk to provide for increased reproducibility of the PZT calibration response. The second zone is densely textured and serves to clean the glide head prior to its use in the calibration zone.

US Patent:

6771453, Aug 3, 2004

Filed:

Nov 5, 2001

Appl. No.:

10/011474

Inventors:

Bradley Frederick Baumgartner - Los Banos CA
Norman H. Chu - San Francisco CA
Shanlin Duan - Fremont CA
Patricia Galindo - Sunnyvale CA
Roger Yu Lo - Fremont CA
Connie H. Moy - San Jose CA
Hang Fai Ngo - San Jose CA

Assignee:

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

International Classification:

G11B 2102

US Classification:

360 75, 360 25

Abstract:

A calibration method for determining the flying height of a glide slider for disk glide height testing is disclosed. The method utilizes a disk with bumps in situ on a disk glide height tester. The method automatically takes into account disk topography, mounting tolerances, and slider roll.

US Patent:

7064659, Jun 20, 2006

Filed:

Aug 31, 2004

Appl. No.:

10/931316

Inventors:

Bradley Frederick Baumgartner - Los Banos CA, US
Norman Chu - San Francisco CA, US
Patricia Galindo - Morgan Hill CA, US
Hang Fai Ngo - San Jose CA, US
Yu Lo - Foster City CA, US
Nalin Zhou - San Jose CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

International Classification:

G08B 29/00

US Classification:

340514, 360 25, 360 31, 324212

Abstract:

A method is presented for glide testing a disk which tests the glide head fly-height by inducing a collision between the glide head and a disk under test. The glide test system is initially calibrated using calibration disks. The method of the invention periodically tests the calibration without interrupting the production testing by lowering the rotation rate until the glide head collides with the rotating disk surface. The rotation rate at which the collision occurs is then compared with the value expected based on knowledge of disk samples and the initial calibration. Parameters for acceptable high and low values are established to detect changes in the glide test system performance to trigger automatic or manual recalibration.

US Patent:

7121133, Oct 17, 2006

Filed:

May 28, 2004

Appl. No.:

10/857195

Inventors:

Norman Chu - San Francisco CA, US
Shanlin Duan - Fremont CA, US
Patricia Galindo - Morgan Hill CA, US
Hang Fai Ngo - San Jose CA, US
Yu Lo - Foster City CA, US
Nalin Zhou - San Jose CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

International Classification:

G01B 7/34

US Classification:

73 189

Abstract:

A glide head calibration technique uses two fly height calibrations on a disk media certifier. The first calibration point uses a spin down on bump technique at a first height, and the second calibration point uses a spin down on disk media roughness at a second lower height. With two height data points, a fly height curve of each glide head is approximated very accurately. Once the fly height curve is derived for each head, any fly height can be dialed-in by the disk media certifier for glide testing. This technique achieves glide fly heights between about 4 nm and 8 nm and does so with improved tolerances.

US Patent:

7164557, Jan 16, 2007

Filed:

Feb 23, 2004

Appl. No.:

10/784506

Inventors:

Parul Agrawal - Saratoga CA, US
Hang Fai Ngo - San Jose CA, US
Charles Lee - San Jose CA, US
Li-Chung Lee - Saratoga CA, US
Ullal Vasant Nayak - San Jose CA, US
Stephen Olson - Palo Alto CA, US
Robert N. Payne - San Jose CA, US
Christopher Ramm - San Jose CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands BV - Amsterdam

International Classification:

G11B 5/60

US Classification:

3602362, 3602364, 3602365, 3602369, 360237

Abstract:

An air bearing burnish slider burnishes very small asperities and cleans the loose particles that adhere to the magnetic recording media. The slider applies a controllable contact force to effectively burnish disk asperities or partially attached particles. In addition, the slider cleans the loose particles effectively while flying in a stable fashion. In a low pitch design, diagonal rails push particles away from the disk surface and trailing edge pads contact the disk at lower linear velocities. Rail pads retain loose contamination and debris in their pockets and burnish asperities. Another design provides a milder burnish force and flies in a high pitch configuration. The trailing edge pads provide stable contacts and the rails help in sweeping away debris. In both designs, the contact forces can be controlled by adjusting linear velocities. A step taper at the leading edge provides a pitch-producing lift force.

US Patent:

20020162204, Nov 7, 2002

Filed:

Jan 14, 1999

Appl. No.:

09/231424

Inventors:

FRANCIS CHEE-SHUEN LEE - SAN JOSE CA, US
MICHAEL LEE MCGHEE - SAN JOSE CA, US
SALVADOR NAVARRO - HOLLISTER CA, US
ULLAL VASANT NAYAK - SAN JOSE CA, US
HANG FAI NGO - SAN JOSE CA, US

International Classification:

B24B039/00

US Classification:

029/090010

Abstract:

A method and apparatus for providing a low cost contact burnish slider is disclosed that can remain in contact or at the initial low flying heights even as the pad surfaces and leading edges wear. The burnish slider includes a body having a leading edge and a trailing edge and an air bearing surface being configured at the leading edge of the body to cut disk asperities as the slider flies and configured away from the leading edge to maintain a flying attitude wherein the leading edge is near the data recording surface and to provide restoring forces to maintain the flying attitude. The air bearing surface may include a front pad proximal to the leading edge and a rear pad distal to the leading edge. Alternatively, the air bearing surface may include two front pads proximal to the leading edge on opposite sides of the body and two rear pads distal to the leading edge and disposed on opposite sides of the body. The front and rear pad(s) extends substantially across the body of the slider. An offset pivot is provided for constraining the moment balance of the slider to provide a low pitch flying attitude. The rear pad(s) further includes a mechanical taper proximal to the trailing edge to minimize load/unload damage. The air bearing surface configuration away from the leading edge provides a force that restores the flying attitude to the slider when an impulse lifting the leading edge is encountered.