Magneto-optical recording medium and method for recording and reproduction thereon
US5923625A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 16, 1997 |
| Grant date | Jul 13, 1999 |
| Priority date | — |
| Expiry date | Dec 16, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10586
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 .lambda..sub.1, are different from those obtained upon reproduction at a wavelength .lambda..sub.2. The two magnetic layers, on which a signal (a) is recorded, are irradiated with light beams having the wavelengths .lambda..sub.1 and .lambda..sub.2 respectively. 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).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.