Optical disk, and method and apparatus for reproducing information recorded in optical disk
US6891788B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 2003 |
| Grant date | May 10, 2005 |
| Priority date | — |
| Expiry date | Jul 10, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical disk is provided for recording data of a signal modulated according to a predetermined modulation method in a form of concavo-convex pits. The optical disk includes a first area having a reflecting film partly removed, and a second area for recording pits which are different from pits satisfying requirements of the predetermined modulation method. The first area having the reflecting film partly removed includes a portion which is formed by removing the reflecting film, and has a length longer than a maximum pit length determined by the modulation method in a circumferential direction of the optical disk. When the pits recorded on the optical disk are physically copied as they are, physical copying of the optical disk can be prevented by utilizing such a difference that the authorized optical disk differs from a pirated copy in a combination of the respective reproduced signals of the first and second areas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.