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. 18, 2000
Filed:
Feb. 18, 1999
Masaya Nagasawa, Yokohama, JP;
Masatoshi Sato, Machida, JP;
Nikon Corporation, Tokyo, JP;
Abstract
An information reproduction method and apparatus reproduces information recorded on an optical disk by projecting a beam of light that has a variable power, determined according to its position in the radial direction of the optical disk. According to a first embodiment of the invention, the projection of the beam of light is moved to the outer perimeter of the radius of the optical disk when it is not possible to move the beam of light so as to correctly follow the information recording tracks formed on the optical disk. As an alternative to the first embodiment (or in addition thereto), the projection of the light beam can be controlled such that the focus of the beam of light is removed from the recording surface of the optical disk when it is not possible to move the beam of light so as to correctly follow the information recording tracks formed on the optical disk. For example, the light beam can be focused on a point further than (i.e., beyond) the surface of the disk. As another alternative, the beam of light is projected at or below the power that does not destroy the recorded information at the innermost perimeter of the optical disk during seek actions that occur when changing the tracks to be reproduced. When the seek actions end and the intended tracks are recorded, the power of the beam of light is set to the power necessary to reproduce those tracks.