The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 30, 2001
Filed:
Oct. 22, 1998
TEAC Corporation, Tokyo, JP;
Abstract
A CD-ROM drive is disclosed which is for use with disks having various degrees of spindle hole eccentricity and data track eccentricity. The hole eccentricity of each disk manifests itself during disk rotation as periodic vibration of the disk and, in consequence, periodic departures of the light beam spot from the track to an extent proportional to the speed of disk rotation, whereas the track eccentricity manifests itself during disk rotation as periodic departures of the beam spot from the track to a constant extent regardless of the speed of disk rotation. Therefore, on being loaded into the disk drive, each disk has its hole eccentricity and track eccentricity measured at two different disk eccentricity check speeds in terms of, for example, the amplitude of an eccentricity-caused periodic component of a tracking error signal. The hole eccentricity of the disk is ascertainable by subtracting the eccentricity measurement at the lower check speed from that at the higher check speed. A speed suitable for reading the disk, at which speed the disk will cause no inconvenient vibration, is determined on the basis of the thus ascertained hole eccentricity thereof.