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:
Feb. 05, 2008
Filed:
Sep. 20, 2002
Toshifumi Tanaka, Tokyo, JP;
Toshifumi Tanaka, Tokyo, JP;
TDK Corporation, Tokyo, JP;
Abstract
An optical recording medium has a plurality of laminated information recording layers. The average reflectivity within a stipulated range in the unrecorded regions of at least one of the information recording layers has a value between the reflectivity in the crystalline state and the reflectivity in the amorphous state. When the focus of the laser beam is aligned to one information recording layer, the difference in reflectivity is small between the case in which those regions of the other information recording layer on which the beam spot shines is a recorded region and the case in which it is an unrecorded region, and even in the case that a boundary between a recorded region and an unrecorded region is present within the beam spot, the distribution of reflectivity within the beam spot becomes constant, so the stable recording and/or playback can be performed.