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. 22, 2005
Filed:
Mar. 29, 2001
Taizou Hamada, Osaka, JP;
Hideyuki Hashi, Osaka, JP;
Tatsuaki Ishida, Shiga, JP;
Nobuyuki Komura, Kyoto, JP;
Yasuaki Ban, Osaka, JP;
Keizo Miyata, Osaka, JP;
Kiyokazu Tohma, Osaka, JP;
Taizou Hamada, Osaka, JP;
Hideyuki Hashi, Osaka, JP;
Tatsuaki Ishida, Shiga, JP;
Nobuyuki Komura, Kyoto, JP;
Yasuaki Ban, Osaka, JP;
Keizo Miyata, Osaka, JP;
Kiyokazu Tohma, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A master disc capable of conducting a preformat recording by a magnetic transcription without causing any unevenness over an entire magnetic disc is provided. The master disc is provided with a radial land portion where an array of ferromagnetic thin films is formed and a concave portion against the land portion. The land portion and the concave portion are formed such that the land portion is joined with the surface of the magnetic disc when the present magnetic disc is overlapped on the magnetic disc, and that the concave portion is not contacted with the surface of the magnetic disc, and also that a space surrounded by the surface of the magnetic disc and the concave portion is open to air at a peripheral end portion of the magnetic disc.