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:
Jul. 24, 2001
Filed:
May. 20, 1999
Mitsuaki Oshima, Kyoto, JP;
Shinichi Konishi, Nara, JP;
Shin-ichi Tanaka, Kyotanabe, JP;
Kenji Koishi, Sanda, JP;
Mitsurou Moriya, Ikoma, JP;
Yoshiho Gotoh, Osaka, JP;
Yoshinari Takemura, Settsu, JP;
Norio Miyatake, Kobe, JP;
Motoyoshi Murakami, Hirakata, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical disk and a method for storing write-once information usable for preventing the illegal copies. The optical disk comprises a disk substrate, and a recording layer having a magnetic film disposed on the disk substrate. The optical disk stores write-once information formed by first recording areas and second recording areas and the write-once information being different for each disk. The second recording areas are formed as a plurality of stripe-shaped marks that are oblong in a radial direction of the disk by irradiating laser light based on a modulation signal of the write-once information in the pre-determined portion of the recording layer, in a manner that a magnetic anisotropy in a direction perpendicular to a surface of the second recording areas is smaller than a magnetic anisotropy in a direction perpendicular to a surface of the first recording areas.