Optical disc and a recording and/or reproducing apparatus having copy-protection function
US5570339A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 21, 1994 |
| Grant date | Oct 29, 1996 |
| Priority date | — |
| Expiry date | Jul 21, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/261
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A copy protected optical disc is recorded with digital data and a key information forming track turns of a predetermined pitch, in which the digital data are converted to a string of signal waveforms in a predetermined encoding scheme defined by the key information, the key information is recorded in a form of single frequency or FM carrier signal modulating the string of signal waveforms carrying the digital data in such a pit configuration that a width of the series of pits in a radial direction of the optical disc is deviated symmetrically with respect to a center of each track turn having a maximum width smaller than the predetermined pitch. And a recording apparatus for the disc comprises a converting device converting the digital data into a string of signal waveforms in a predetermined encoding scheme defined by the key information, a carrier generating device generating a carrier signal related to the key information, and a modulating device modulating a light beam with the digital data together with the carrier signal and record the data and the carrier signal as a series of pits on the disc, whereas a reproducing apparatus for the disc comprises detecting device detecting…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.