Optical disc, device for checking optical disc and device for recording information on optical disc
First Claim
1. An optical disc comprising:
- a predetermined number of spiral trains of regular pits; and
at least one train of irregular pits;
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;
the train of the irregular pits having information causing a tracking error signal.
1 Assignment
0 Petitions
Accused Products
Abstract
An optical disc on which a number of spiral trains of regular pits and at least one train of irregular pits are formed. The regular pits of each of the trains is arranged symmetrically with respect to the center of a track. Each of the irregular pits has a predetermined shape different from a shape of each of the regular pits. An arrangement of the train of the irregular pits being differs from an arrangement of each of the trains of the regular pits. A tracking error signal being obtained from the train of the irregular pits. An irregular pit can not be copied even when a normal optical disc containing such an irregular pit is copied by performing a conventional copying method. Thus, an illegal copy disc can be discriminated from a normal optical disc by checking whether or not an irregular pit is included in an optical disc to provide good copy protection by easily detecting an illegal copy disc.
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Citations
38 Claims
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1. An optical disc comprising:
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a predetermined number of spiral trains of regular pits; and at least one train of irregular pits; 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; the train of the irregular pits having information causing a tracking error signal. - View Dependent Claims (4, 5, 6, 7, 8, 12, 13, 18, 19, 20)
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2. 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. - View Dependent Claims (9, 10, 11, 14, 15, 16, 17, 29, 30)
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3. 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. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 31, 32)
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33. An optical disc comprising:
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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. - View Dependent Claims (34, 35, 36, 37)
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38. An optical disc comprising:
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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.
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Specification