Optical disk with copy protection, and apparatus and method for recording and reproducing same
US5809006A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 1996 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | May 31, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/00601
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Copy-protected optical disk format, optical disk recording apparatus for creating disks having such formats and optical disk reading apparatus for reading disks having such formats and for determining whether the disks are authentic. In one aspect, an authentic optical disk has data bit indications along a spiral centerline of the disk, and these data bit indications define a radial wobble which has substantially greater energy at a predefined frequency f.sub.CPW (such as f.sub.CC /392) than at a frequency of f.sub.CC /196, where f.sub.CC is the spatial channel clock frequency. In another aspect, an authorized optical disk has data bit indications along a substantially spiral centerline of the disk, according to a channel clock whose frequency varies across the disk. The disk further has stored thereon an indication of the number of such channel clock cycles which occur along a predetermined test segment of the centerline, optionally together with a pointer to the test segment. Since normal data stream copying techniques do not copy the exact channel clock rates on the disk, and since the copying equipment will inherently introduce its own channel clock variations across the result…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.