EP0252502A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical information recording and reproducing apparatus with tracking control by sampling
Assignee: Hitachi Ltd
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Filing: 1987-07-08
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Granted: —
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Expires: 2007-07-08
Abstract
Abstract An optical information recording and reproducing apparatus of a sampling servo system which effects the tracking by holding the differential output of the reproduced signals of tracking pits that are wobbled toward the right and left relative to the track of the optical disk. Reproduced signals of a plurality of pits arranged maintaining a distance on the track and wobbled toward the right or left in a servo signal region, are compared with each other to detect any abnormal condition in the tracking pits. When the abnormal condition is detected, the tracking signal that is sampled is not used, but instead the tracking signal sampled under the normal condition is continuously used to perform the tracking control.
Inventors
- 👤 Wasao Takasugi
- 👤 Seiji Yonezawa
- 👤 Toshiaki Tsuyoshi
- 👤 Masatoshi Ohtake
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 07:48
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0938; G11B7/0948
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
242 words
An optical information recording and reproducing apparatus comprising: a mechanism (4) for rotating a recording medium (6) which has servo signal regions (2) and data regions (3) arranged alternatingly in the direction of rotation, each servo signal region containing at least a pair of tracking pits (L, R) that are wobbled toward the right and left relative to the center of the track an optical head (1O) which projects a light spot onto said recording medium and which detects the reflected light; tracking detection means (2O) which detects a difference between a reproduced signal of a pit wobbled toward the left side and a reproduced signal of a pit wobbled toward the right side in said servo region among the reproduced signals sent from said optical head, and which holds said difference as a tracking signal; a tracking control mechanism (6O) which controls the relative position of said light spot using said tracking signal; error detection means (3O) which detects a difference between the reproduced signals of pits that are wobbled toward at least either the right or left in said servo signal region among the reproduced signals sent from said optical head, and which detects the abnormal condition relying upon said difference signal; and error protection means (4O) which, when the output of said error detection means indicates the occurrence of error, inhibits the tracking signal produced by said tracking detection means from being used for controlling said tracking control mechanism.
Claim 2
Dependent Claim
242 words
An optical information recording and reproducing apparatus comprising: a mechanism (4) for rotating a recording medium (6) which has servo signal regions (2) and data regions (3) arranged alternatingly in the direction of rotation, each servo signal region containing at least a pair of tracking pits (L, R) that are wobbled toward the right and left relative to the center of the track an optical head (1O) which projects a light spot onto said recording medium and which detects the reflected light; tracking detection means (2O) which detects a difference between a reproduced signal of a pit wobbled toward the left side and a reproduced signal of a pit wobbled toward the right side in said servo region among the reproduced signals sent from said optical head, and which holds said difference as a tracking signal; a tracking control mechanism (6O) which controls the relative position of said light spot using said tracking signal; error detection means (3O) which detects a difference between the reproduced signals of pits that are wobbled toward at least either the right or left in said servo signal region among the reproduced signals sent from said optical head, and which detects the abnormal condition relying upon said difference signal; and error protection means (4O) which, when the output of said error detection means indicates the occurrence of error, inhibits the tracking signal produced by said tracking detection means from being used for controlling said tracking control mechanism.
Claim 3
Dependent Claim
38 words
An optical information recording and reproducing apparatus according to claim l, wherein said error detection means (3O) detects a difference in the reproduced signals from a plurality of pits wobbled toward the same side in a servo region.
Claim 4
Dependent Claim
40 words
An optical information recording and reproducing apparatus according to claim l, wherein said error detection means (3O) detects a difference in the reproduced signals among the pits that are arranged at corresponding positions in a plurality of neighboring servo regions.
Claim 5
Dependent Claim
40 words
An optical information recording and reproducing apparatus according to claim l, wherein said error protection means (4O) continues to produce the tracking signal detected under normal condition when the output of said error detection means indicates the occurrence of error.
Claim 6
Dependent Claim
75 words
An optical information recording and reproducing apparatus according to claim 4, wherein said error protection means (4O) includes a sample and hold circuit (4l) which samples and holds an output immediately after it is produced from said tracking detection means, and an inhibit gate (42) which, in response to the output of said error detection means, inhibits the input of a timing signal (45O) that gives a sampling timing to said sample and hold circuit.
Claim 7
Dependent Claim
59 words
An optical information recording and reproducing apparatus according to claim l, wherein said error protection means (4O) produces a signal that is obtained by the first order extrapolation from the tracking signal obtained in the previous time and from the tracking signal obtained two times before, when the output of said error detection means indicates the occurrence of error.
References Cited (Backward Citations)
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