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:
Dec. 04, 2001
Filed:
Jun. 19, 2000
Applicant:
Inventors:
Hideyo Kamiyama, Saitama-ken, JP;
Akira Kawakami, Saitama-ken, JP;
Assignee:
Pioneer Electronics Corporation, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/00 ;
U.S. Cl.
CPC ...
G11B 7/00 ;
Abstract
A laser beam is focused at positions on an optical axis of the optical pickup by a focusing device, corresponding to kinds of the discs which are different in thickness. The focusing device is moved along the optical axis. A photodetector is provided for receiving a laser beam reflected from the disc and for producing a focus error signal. A detector is provided for detecting the difference between the focus error signals, caused by the difference in thickness of the discs and the difference in focal point of the laser beam, thereby discriminating the kind of the disc.