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:
Mar. 26, 1991
Filed:
Dec. 23, 1988
Hidetoshi Ikeda, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
An optical disk apparatus for reading and writing information on an optical disk having concentric tracks. The objective lens is accurately positioned in both a tracking mode and a coarse access mode. During the tracking mode, a tracking detector detects a light beam reflected off of the optical disk and generates a tracking error signal. During the coarse access mode, a position detector detects the position of the objective lens and generates a position signal. The position signal generated when the objective lens is in an initial position is stored, and the stored signal is compared with the signals generated during the coarse accessing mode to produce a signal which represents the difference between the initial position of the objective lens and the current position of the objective lens. A coil is operated to move the objective lens in both the tracking mode and the coarse accessing mode. During the tracking mode, the objective lens follows a track on the optical disk, and during the coarse accessing mode, the objective lens is held in the initial position.