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. 12, 1999
Filed:
Sep. 12, 1997
Shigeru Shimonou, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An optical disk apparatus includes first and second objective lenses, a carriage, a moving mechanism, a fixed optical system, a main control section, track access control circuits, a first positional shift correction circuit, a second positional shift correction circuit, first and second driving members, an arithmetic circuit, and a correction member. The first and second driving members slightly drive the first and second objective lenses in a track crossing direction in accordance with the first and second positional shift correction signals, respectively. The first and second positional shift correction circuits count first and second track position signals to output first and second positional error signals with respect to a target track, and output the first and second positional shift correction signals to the first and second driving members based on the first and second positional error signals and the first and second track position signals, respectively. The arithmetic circuit calculates a difference between the first and second positional error signals to output an inter-beam positional shift signal. The correction member corrects one of the first and second positional shift correction signals based on the inter-beam positional shift signal.