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:
Oct. 26, 1999
Filed:
Oct. 28, 1997
Applicant:
Inventors:
Masayuki Tamura, Fukaya, JP;
You Yoshioka, Yokohama, JP;
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 4429 ; 369 4427 ; 369 4425 ; 369 94 ; 2502015 ;
Abstract
In making a layer jump or focus search on a multilayer optical disk having two or more signal recorded layers, an objective lens is moved in a focusing direction to focus a laser beam onto a desired signal recorded layer with focus servo kept OFF. Based on the number of times a focus error signal having an S-shaped characteristic obtained as a result of driving the objective lens exceeds a predetermined voltage level, arrival at the desired signal recorded layer is determined. In this state, the focus servo is made active at the time when the focus error signal first goes to the 0 level.