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

• US 5,570,339 A
• Filed: 07/21/1994
• Issued: 10/29/1996
• Est. Priority Date: 07/22/1993
• Status: Expired due to Fees

• Current Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Original Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Inventors: Nagano, Hirofumi
• Primary Examiner(s): Hindi, Nabil Z.
• Application Number:
  US08/278,422
• Time in Patent Office: 831 Days
• Field of Search: 369/54, 369/58, 369/48, 369/47, 369/59, 369/32, 369/275.3, 369/275.4, 360/60, 380/3, 380/4, 380/5
• US Class Current: 369/275.3
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00586 said format change concerning the physical format of the recording medium
• CPC Class Codes: G11B 20/00594 wherein the shape of recording marks is altered, e.g. the depth, width, or length of pits
• CPC Class Codes: G11B 7/00736 Auxiliary data, e.g. lead-in, lead-out, Power Calibration Area [PCA], Burst Cutting Area [BCA], control information sector headers or adresses in prepits G11B7/00745; address data in track wobble G11B7/24082
• CPC Class Codes: G11B 7/261 Preparing a master, e.g. exposing photoresist, electroforming

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.

Claims

1. A copy protecting optical disc optically recorded with digital data and a key information as a series of pits forming track turns of a predetermined pitch on the optical disc, the digital data being converted to a string of signal waveforms according to a predetermined encoding scheme defined by the key information, the key information being a form of carrier signal which has a single frequency signal that is much lower in frequency than a frequency of the string of signal waveforms, the single frequency signal modulating the string of signal waveform carrying the digital data in such a pit configuration that each of a plurality of widths 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, and an outer contour and an inner contour of each of the plurality of widths in the radial direction are changed in response to an amplitude of the single frequency signal of the key information, each of the plurality of widths of the series of pits having a maximum width smaller than the predetermined pitch.

2. A copy protecting optical disc optically recorded with digital data and a key information as a series of pits forming track turns of a predetermined pitch on the optical disc, the digital data being converted to a string of signal waveforms according to a predetermined encoding scheme defined by the key information, the key information being a form of carrier signal which is an FM frequency signal that is much lower in frequency than a frequency of the string of signal waveforms, the FM frequency signal of the key information modulating the string of signal waveforms carrying the digital data in such a pit configuration that each of a plurality of widths 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, and an outer contour and an inner contour of each of the plurality of widths of the series of pits are changed in response to an amplitude of the FM frequency of the key information, each of the plurality of widths of the series of pits having a maximum width smaller than the predetermined pitch.