Magneto-optical disk having write-once identification marks and method for recording thereof
US6266299A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1999 |
| Grant date | Jul 24, 2001 |
| Priority date | — |
| Expiry date | May 20, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2020/1245
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.