US4542425A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for reading a record carrier
Assignee: Arkema Inc
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Filing: 1982-12-23
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Granted: 1985-09-17
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Expires: 2002-12-23
Abstract
Abstract The invention relates to apparatus for reading a record carrier on which digital information and tracking signals of comparatively low frequency have been recorded. The apparatus comprises a correction circuit to which the regenerated digital signal is applied, which correction circuit has a transfer characteristic which at least within the frequency band of the tracking signals corresponds to the transfer characteristic of the chain comprising the recording element, the record carrier and the read element. The correction signal supplied by the correction circuit is subtracted from the signal that is read and the tracking signals are derived from the signal thus obtained. In this way cross-talk components produced in the tracking signals by the digital signal are compensated for.
Inventors
- 👤 Edmond de Niet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:23
CPC Classifications
G; G11; G11B; G11B21/00; G11B21/02; G11B21/10; G11B15/00; G11B15/18; G11B15/46; G11B15/463; G11B5/00; G11B5/48; G11B5/58
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
248 words
An apparatus for reading a record carrier which comprises information tracks which in addition to an information signal also contain tracking signals, which apparatus comprises a read element for reading the information recorded in the information tracks, a signal-processing circuit for processing the information signal present in the information that is read and a servo control system for deriving an error signal fron the tracking signals extracted from the information that is read, which error signal is representative of the position of the read element relative to the information track that is being read in a direction transverse to the track direction and tfor controlling the position of said read element relative to said information track in response to said error signal, characterized in that for reading a record carrier on which a digital information signal has been recorded the signal processing circuit is adapted to regenerate said digital information signal, the apparatus further comprises a correction circuit, which is coupled to said signal processing circuit, for receiving the regenerated digital information signal, and the servo control system comprises a compensation circuit, which is coupled to the output of the correction circuit, for reducing cross-talk components of the digital information signal in the tracking signals, said correction circuit having a transfer characteristic which at least within the frequency band of the tracking signals at least approximates the transfer characteristic of the chain comprising the recording element used for recording the information, the record carrier and the read element.
Claim 2
Independent Claim
248 words
An apparatus for reading a record carrier which comprises information tracks which in addition to an information signal also contain tracking signals, which apparatus comprises a read element for reading the information recorded in the information tracks, a signal-processing circuit for processing the information signal present in the information that is read and a servo control system for deriving an error signal fron the tracking signals extracted from the information that is read, which error signal is representative of the position of the read element relative to the information track that is being read in a direction transverse to the track direction and tfor controlling the position of said read element relative to said information track in response to said error signal, characterized in that for reading a record carrier on which a digital information signal has been recorded the signal processing circuit is adapted to regenerate said digital information signal, the apparatus further comprises a correction circuit, which is coupled to said signal processing circuit, for receiving the regenerated digital information signal, and the servo control system comprises a compensation circuit, which is coupled to the output of the correction circuit, for reducing cross-talk components of the digital information signal in the tracking signals, said correction circuit having a transfer characteristic which at least within the frequency band of the tracking signals at least approximates the transfer characteristic of the chain comprising the recording element used for recording the information, the record carrier and the read element.
Claim 3
Dependent Claim
36 words
An apparatus as claimed in claim 1, for reading a magnetic record carrier, characterized in that the correction circuit has a transfer characteristic which at least substantially corresponds to the transfer characteristic of the read element.
Claim 4
Dependent Claim
16 words
An apparatus as claimed in claim 2, characterized in that the correction circuit comprises a differentiator.
References Cited (Backward Citations)
US4464714A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-09-16 | 1989-03-18 | 1989-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-16 | 1993-03-18 | 1993-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-16 | 1997-03-18 | 1997-09-17 | $7700.00 | Window Closed / Lapsed |