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. 05, 1999
Filed:
May. 07, 1996
Applicant:
Inventors:
Assignee:
Sanyo Electric Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 58 ; 369110 ; 369112 ; 369121 ;
Abstract
An optical disc readout apparatus having an optical system which guides a laser beam onto a signal recording surface of a loaded disc through an objective lens and guides a reflected laser beam onto a photo detector. An effective numerical aperture of the objective lens is adjusted according to the thickness between a substrate surface of the loaded disc and the signal recording surface, and the laser spot with a diameter suitable to a recording density of the loaded disc is focused on the signal recording surface. Therefore, the data recorded in a plurality of optical discs with different thickness or recording densities can be read out.