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:
Sep. 16, 2003
Filed:
Jan. 21, 1999
Kazuhiko Nemoto, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical head comprises a first optical system which irradiates a light of a first wavelength towards the information recording medium and detects a return part of the light reflected by the information recording medium, and a second optical system which irradiates a light of a second wavelength shorter than the first wavelength towards the information recording medium and detects a return part of the light reflected by the information recording medium. When writing or reading information with respect to the information recording medium using the second optical system, a pushpull signal is detected by the second optical system, and an offset component of the pushpull signal is canceled by a signal detected by the first optical system.