Copy protection marks on a transparent layer of an optical disk indicating that the disk has been previously accessed
US6104686A · kind A · utility
18Cited by
5References
14Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 26, 1998 |
| Grant date | Aug 15, 2000 |
| Priority date | — |
| Expiry date | Jan 26, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B23/36
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for constructing an optical disk and a method of signal detection which permits a read only device, such as a CD-ROM or DVD-ROM reader, to create a permanent mark on a disk in such a way that it can be subsequently determined that the disk had been previously accessed is disclosed. Such a disk facilitates the operation of CD-ROM or DVD-ROM based systems where the behavior depends on whether or not the information on the optical disk had been previously accessed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.