Optical disc, device for checking optical disc and device for recording information on optical disc

A checking device for checking whether an optical disc is a normal disc or an illegal copy disc, wherein

• the normal disc has a predetermined number of spiral trains of regular pits and at least one train of irregular pits arranged in a given area of the normal disc,
• the regular pits of each of the trains being arranged symmetrically with respect to a center of a track;
• each of the irregular pits having a predetermined shape different from a shape of each of the regular pits;
• an arrangement of the train of the irregular pits being different from an arrangement of each of the trains of the regular pits and being asymmetrical with respect to a center of a track, and
• wherein the illegal copy disc lacks a train of irregular pits in an area thereof which corresponds to the given area of the normal disc;
• the checking device comprising:
• reproducing means for reproducing information from an area of a checked optical disc which corresponds to the given area of the normal disc;
• and
• judgment means for detecting from the information reproduced by the reproducing means whether or not a train of irregular pits is present in the checked optical disc, and for judging from a result of the detection whether the checked optical disc is a normal disc or an illegal copy disc.

A checking device for checking whether an optical disc is a normal disc or an illegal copy disc, wherein

• the normal disc has a predetermined number of spiral trains of regular pits and at least one train of irregular pits arranged in a given area of the normal disc,
• the regular pits of each of the trains being arranged symmetrically with respect to a center of a track;
• each of the irregular pits having a predetermined shape different from a shape of each of the regular pits;
• the irregular pits being arranged intermittently on a predetermined area correspondingly to data blocks represented by a modulation signal recorded as the trains of the regular pits, and
• wherein the illegal copy disc lacks a train of irregular pits in an area thereof which corresponds to the predetermined area of the normal disc;
• the checking device comprising:
• reproducing means for reproducing information from an area of a checked optical disc which corresponds to the predetermined area of the normal disc;
• and
• judgment means for detecting from the information reproduced by the reproducing means whether or not a train of irregular pits is present in the checked optical disc, and for judging from a result of the detection whether the checked optical disc is a normal disc or an illegal copy disc.

An optical disc comprising:

• a predetermined number of spiral trains of regular pits;
• and
• a plurality of trains of irregular pits;
• the regular pits in each of the trains being arranged symmetrically with respect to a center of a track;
• each of the irregular pits having a predetermined shape different from a shape of each of the regular pits;
• an arrangement of each of the trains of the irregular pits being different from an arrangement of each of the trains of the regular pits and being asymmetrical with respect to a center of a track;
• each of the trains of the irregular pits having information causing a tracking error signal.

An optical disc comprising:

• a predetermined number of spiral trains of regular pits;
• and
• at least one unusual area being devoid of regular pits and having a mirror surface, the unusual area being located between two of the trains of the regular pits in a direction along a track;
• the regular pits in each of the trains being arranged symmetrically with respect to a center of a track.