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. 28, 1995
Filed:
Mar. 02, 1993
Miyozo Maeda, Kawasaki, JP;
Mineo Moribe, Kawasaki, JP;
Susumu Satoh, Kawasaki, JP;
Kyoko Miyabe, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An optical disk is adapted for use in an optical disk unit which irradiates a light beam spot on a target track on the optical disk and controls tracking of the light beam spot based on a tracking error signal which is generated based on a reflected light beam from the optical disk. The optical disk includes a disk shaped substrate, a spiral or concentric guide tracks provided on the substrate, a writable region provided on the substrate between two mutually adjacent track turns of the guide track, and a preformed track provided within the guide track and prerecorded with read-only information in a form of variations of a topological feature. The guide track and the topological feature have mutually different height positions so that a tracking error signal which is generated when the light beam spot scans the guide track has the same amplitude as a tracking error signal which is generated when the light beam spot scans the preformed track, and the height positions of the guide track and the topological feature are different from a height position which generates a maximum tracking error signal amplitude when scanned by the light beam spot.