An optical disc and a recording and/or reproducing apparatus having copy-protection function

Abstract

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 the recording codes and the key information recorded on the disc decoding device decoding digital data from the recording codes using the key information.

Inventors

• 👤 Hirofumi Nagano

Bibliographic Details