Optical disc, device for checking optical disc, and device for recording information on optical disc
First Claim
1. An optical disc having a sequence of pits which extends along a track, the pit sequence representing a recorded signal divided into data blocks, the pit sequence including a normal pit train and an unusual pit train, the normal pit train being symmetrical with respect to a center of the track, the unusual pit train being different from the normal pit train in at least one of shape and pit arrangement, the unusual pit train being at a position having a predetermined relation with the data blocks and causing a variation in symmetry of an RF signal.
2 Assignments
0 Petitions
Accused Products
Abstract
An optical disc has a sequence of pits which extends along a track. The pit sequence represents a recorded signal divided into data blocks. The pit sequence includes a normal pit train and an unusual pit train. The normal pit train is symmetrical with respect to a center of the track. The unusual pit train is different from the normal pit train in at least one of shape and pit arrangement. The unusual pit train is at a position having a predetermined relation with the data blocks.
118 Citations
7 Claims
- 1. An optical disc having a sequence of pits which extends along a track, the pit sequence representing a recorded signal divided into data blocks, the pit sequence including a normal pit train and an unusual pit train, the normal pit train being symmetrical with respect to a center of the track, the unusual pit train being different from the normal pit train in at least one of shape and pit arrangement, the unusual pit train being at a position having a predetermined relation with the data blocks and causing a variation in symmetry of an RF signal.
- 3. An optical disc having a sequence of pits which extends along a track, the pit sequence representing a recorded signal divided into data blocks, the pit sequence including a normal pit train and an unusual pit train, the normal pit train being symmetrical with respect to a center of the track, the unusual pit train being different from the normal pit train in at least one of shape and pit arrangement, the unusual pit train being at a position having a predetermined relation with the data blocks, and representing a wobbling signal superimposed on a tracking error signal, wherein the wobbling signal represented by the unusual pit train has a burst shape.
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7. A device for checking an optical disc, comprising:
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first means for reproducing a signal from the optical disc; second means connected to the first means for detecting whether or not an unusual pit train is present in the optical disc by referring to the signal reproduced by the first means, the unusual pit train being different from a normal pit train in at least one of shape and pit arrangement, the normal pit train being symmetrical with respect to a track center; and third means connected to the second means for judging whether the optical disc is a legitimate production or an illegal production in response to a result of the detecting by the second means.
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Specification