Device and program for checking optical disks
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsKoichi Morioka, Takashi Yumiba, Keiichi Kawashima
Life of this patent
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Abstract
A plurality of tracks on an optical disk are optically read to obtain a signal containing a plurality of LOW segments. Each of the plurality of LOW segments should correspond to a certification pit. Accordingly, if the interval between LOW segment Xj and nth succeeding LOW segment Xj+n exceeds the length of one track, a defect pit that could be confused with a certification pit is judged as being present between two certification pits.
Claims15
A check device for checking, when n certification pits are provided on each of a plurality of adjacent tracks on an optical disk to certify that the optical disk is authentic, whether a naturally-occurring defect exists between any two certification pits, n being an integer that satisfies n≧1, each certification pit having a predetermined length that is out of specifications, and the defect having a length substantially equal to the predetermined length, the check device comprising:
- reading means for optically reading the plurality of tracks, to obtain a signal corresponding to the plurality of tracks;
- detecting means for detecting a plurality of signal segments which each have a duration corresponding to the predetermined length, from the signal;
- and
- judging means for judging, if an interval between any signal segment and an nth succeeding signal segment is different from a reference value, that a naturally-occurring defect exists between two certification pits.
A check device for checking, when an optical disk was processed to form n certification pits on each of a plurality of adjacent tracks to certify that the optical disk is authentic, whether any of a naturally-occurring defect and an imperfectly-formed certification pit exists between any two certification pits, n being an integer that satisfies n≧1, each certification pit having a predetermined length that is out of specifications, and the defect having a length substantially equal to the predetermined length, the check device comprising:
- reading means for optically reading the plurality of tracks, to obtain a signal corresponding to the plurality of tracks;
- detecting means for detecting a plurality of signal segments which each have a duration corresponding to the predetermined length, from the signal;
- and
- judging means for judging
- (a) if an interval between any signal segment and an nth succeeding signal segment is shorter than a reference value, that a naturally-occurring defect exists between two certification pits, and
- (b) if the interval is longer than the reference value, that an imperfectly-formed certification pit exists between two certification pits.
A check device for checking, when an optical disk was processed to form n certification pits on each of a plurality of adjacent tracks to certify that the optical disk is authentic, whether any of a naturally-occurring defect and an imperfectly-formed certification pit exists between any two certification pits, n being an integer that satisfies n≧1, each certification pit having a predetermined length that is out of specifications, and the defect having a length substantially equal to the predetermined length, the check device comprising:
- reading means for optically reading the plurality of tracks, to obtain a signal corresponding to the plurality of tracks;
- detecting means for detecting a plurality of signal segments which each have a duration corresponding to the predetermined length, from the signal;
- and
- judging means for judging
- (a) if a number of signal segments detected for any of the plurality of tracks is greater than n, that a naturally-occurring defect exists between two certification pits, and
- (b) if the number of signal segments is smaller than n, that an imperfectly-formed certification pit exists between two certification pits.
A program executed by a computer for checking, when n certification pits are provided on each of a plurality of adjacent tracks on an optical disk to certify that the optical disk is authentic, whether a naturally-occurring defect exists between any two certification pits, n being an integer that satisfies n≧1, each certification pit having a predetermined length that is out of specifications, and the defect having a length substantially equal to the predetermined length, the program comprising:
- a reading step for optically reading the plurality of tracks, to obtain a signal corresponding to the plurality of tracks;
- a detecting step for detecting a plurality of signal segments which each have a duration corresponding to the predetermined length, from the signal;
- and
- a judging step for judging, if an interval between any signal segment and an nth succeeding signal segment is different from a reference value, that a naturally-occurring defect exists between two certification pits.
A program executed by a computer for checking, when an optical disk was processed to form n certification pits on each of a plurality of adjacent tracks to certify that the optical disk is authentic, whether any of a naturally-occurring defect and an imperfectly-formed certification pit exists between any two certification pits, n being an integer that satisfies n≧1, each certification pit having a predetermined length that is out of specifications, and the defect having a length substantially equal to the predetermined length, the program comprising:
- a reading step for optically reading the plurality of tracks, to obtain a signal corresponding to the plurality of tracks;
- a detecting step for detecting a plurality of signal segments which each have a duration corresponding to the predetermined length, from the signal;
- and
- a judging step for judging
- (a) if an interval between any signal segment and an nth succeeding signal segment is shorter than a reference value, that a naturally-occurring defect exists between two certification pits, and
- (b) if the interval is longer than the reference value, that an imperfectly-formed certification pit exists between two certification pits.
A program executed by a computer for checking, when an optical disk was processed to form n certification pits on each of a plurality of adjacent tracks to certify that the optical disk is authentic, whether any of a naturally-occurring defect and an imperfectly-formed certification pit exists between any two certification pits, n being an integer that satisfies n≧1, each certification pit having a predetermined length that is out of specifications, and the defect having a length substantially equal to the predetermined length, the program comprising:
- a reading step for optically reading the plurality of tracks, to obtain a signal corresponding to the plurality of tracks;
- a detecting step for detecting a plurality of signal segments which each have a duration corresponding to the predetermined length, from the signal;
- and
- a judging step for judging
- (a) if a number of signal segments detected for any of the plurality of tracks is greater than n, that a naturally-occurring defect exists between two certification pits, and
- (b) if the number of signal segments is smaller than n, that an imperfectly-formed certification pit exists between two certification pits.
Dependencies are inferred from the claim text.