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:
Sep. 26, 2006
Filed:
May. 28, 1999
Katsusuke Shimazaki, Ibaraki, JP;
Norio Ohta, Ibaraki, JP;
Akiyoshi Ito, Matsudo, JP;
Katsuji Nakagawa, Tokyo, JP;
Kazuko Inoue, Ryugasaki, JP;
Katsusuke Shimazaki, Ibaraki, JP;
Norio Ohta, Ibaraki, JP;
Akiyoshi Ito, Matsudo, JP;
Katsuji Nakagawa, Tokyo, JP;
Kazuko Inoue, Ryugasaki, JP;
Hitachi Maxell, Ltd., Ibaraki, JP;
Abstract
A magneto-optical recording medium and a method for recording and reproduction thereon are provided in order to reproduce information recorded by multi-valued recording at a high S/N ratio. Disclosed is a magneto-optical recording medium including two magnetic layers capable of four-valued recording based on four combined magnetization states. Magnitudes of reproduction signals concerning the four magnetization states, obtained upon reproduction at a wavelength λ, are different from those obtained upon reproduction at a wavelength λ. The two magnetic layers, on which a signal (a) is recorded, are irradiated with light beams having the wavelengths λand λrespectively. Signals (d), (e) reproduced from respective reflected light beams are sliced by using at least one slice level to obtain two-valued or higher multi-valued reproduction signals respectively. The two-valued or higher multi-valued reproduction signals (f), (g) from the respective wavelengths are mutually subjected to logical operation to reproduce recorded information (i).