Andrew J Buhler

Address:

5697 Venado Ct, San Jose, CA 95123

Phone:

408 365-3589

VIN:

WBAVA37507NL17471

Make:

BMW

Model:

3 SERIES

Year:

2007

US Patent:

20020118630, Aug 29, 2002

Filed:

Feb 26, 2001

Appl. No.:

09/793236

Inventors:

Bradley Baumgartner - Los Banos CA, US
Andrew Buhler - San Jose CA, US
Erich Chuh - San Mateo CA, US
Hang Ngo - San Jose CA, US
Bob Robinson - Hollister CA, US
Elmer York - San Jose CA, US

Assignee:

International Business Machines Corporation

International Classification:

G11B005/82

US Classification:

369/135000

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. The rotational position of the spindle also is relayed to the computer for coordinating the processing of the rotating disk. When the disk is mounted on a different tool, the same shadow signature is used to determine its planar and angular positions.