Patent US5105409A successfully refreshed from Google Patents.
US5105409A
Expired / Lapsed
US
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Method and apparatus for optical recording and reproduction with tracking servo reducing track offset
Assignee: Hitachi Ltd
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Filing: 1988-08-11
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Granted: 1992-04-14
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Expires: 2008-08-11
Abstract
Abstract Disclosed is an optical recording and reproducing apparaus comprising a light source directing a light spot toward a recording medium, a detection system detecting light reflected from the recording medium to derive an electrical signal from the reflected light, an information processing circuit modulating the intensity of the light spot according to writing pulses to record information on the recording medium and using the electrical signal to reproduce information from the recording medium, and a tracking servo circuit carrying out tracking servo operation on the basis of the electrical signal and including an extracting circuit connected to a source of extracting pulses having a pulse width at least equal to the writing pulse width so that writing pulse parts contained in the electrical signal are extracted during recording information, whereby a track offset occurring during information recording can be minimized, and the stability of the tracking servo system can be improved.
Inventors
- 👤 Toshimitsu Kaku
- 👤 Kazuo Shigematsu
- 👤 Hisataka Sugiyama
- 👤 Takeshi Maeda
- 👤 Masahiro Takasago
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:33
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/094
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
159 words
An optical recording and reproducing apparatus comprising: light illuminating means for illuminating a light spot toward a recording medium; a detection system detecting light reflected from said recording medium to derive an electrical signal from said reflected light; an information processing circuit modulating the intensity of said light spot according to writing pulses to record information on said recording medium and using said electrical signal to reproduce information from said recording medium; and a tracking servo circuit carrying out a tracking servo operation on the basis of said electrical signal, said tracking servo circuit including an extracting circuit for extracting time-wise portions of said electrical signal, and means for applying extracting pulses having a pulse width at least equal to the writing pulse width to said extracting circuit so that time-wise portions of said electrical signal corresponding to the writing pulses during recording of information are not utilized for the tracking servo operation when the extracting pulses are present.
Claim 2
Dependent Claim
159 words
An optical recording and reproducing apparatus comprising: light illuminating means for illuminating a light spot toward a recording medium; a detection system detecting light reflected from said recording medium to derive an electrical signal from said reflected light; an information processing circuit modulating the intensity of said light spot according to writing pulses to record information on said recording medium and using said electrical signal to reproduce information from said recording medium; and a tracking servo circuit carrying out a tracking servo operation on the basis of said electrical signal, said tracking servo circuit including an extracting circuit for extracting time-wise portions of said electrical signal, and means for applying extracting pulses having a pulse width at least equal to the writing pulse width to said extracting circuit so that time-wise portions of said electrical signal corresponding to the writing pulses during recording of information are not utilized for the tracking servo operation when the extracting pulses are present.
Claim 3
Dependent Claim
42 words
An optical recording and reproducing apparatus according to claim 1, wherein the pulse width of said extracting pulses applied to said extracting circuit is determined while taking into account the frequency characteristics of a tracking servo signal of said tracking servo circuit.
Claim 4
Dependent Claim
40 words
An optical recording and reproducing apparatus according to claim 1, wherein said tracking servo circuit includes a gain change-over circuit for changing over the gain of said tracking servo circuit depending on whether information is to be recorded or reproduced.
Claim 5
Dependent Claim
49 words
An optical recording and reproducing apparatus according to claim 1, wherein the means for applying extracting pulses applies the extracting pulses to the extracting circuit at a timing corresponding to a timing of the writing pulses, the tracking servo circuit including a tracking servo loop with a variable gain.
Claim 6
Dependent Claim
142 words
An optical disk apparatus comprising: a light source; an optical system guiding light emitted from said light source toward a recording medium on a disk plate; an information detection circuit separating light reflected from said recording medium on said disk plate from said optical system and photoelectrically converting said reflected light into an electrical signal; an information processing circuit recording and reproducing information on and from said recording medium on said disk plate; and means connected to said information detection circuit for applying extracting pulses having a pulse width at least equal to that of writing pulses for recording of information to said information detection circuit so that time-wise portions of said electrical signal corresponding to the writing pulses during recording of information are not utilized for a tracking servo operation of a tracking servo circuit when the extracting pulses are present.
Claim 7
Dependent Claim
142 words
An optical disk apparatus comprising: a light source; an optical system guiding light emitted from said light source toward a recording medium on a disk plate; an information detection circuit separating light reflected from said recording medium on said disk plate from said optical system and photoelectrically converting said reflected light into an electrical signal; an information processing circuit recording and reproducing information on and from said recording medium on said disk plate; and means connected to said information detection circuit for applying extracting pulses having a pulse width at least equal to that of writing pulses for recording of information to said information detection circuit so that time-wise portions of said electrical signal corresponding to the writing pulses during recording of information are not utilized for a tracking servo operation of a tracking servo circuit when the extracting pulses are present.
Claim 8
Dependent Claim
41 words
An optical disk apparatus according to claim 5, wherein the pulse width of said extracting pulses applied to said information detection circuit is determined while taking into account the frequency characteristics of a tracking servo signal of said tracking servo circuit.
Claim 9
Dependent Claim
48 words
An optical disk apparatus according to claim 5, wherein the means for applying extracting pulses applies the extracting pulses to said information detection circuit at a timing corresponding to a timing of the writing pulses, the tracking servo circuit including a tracking servo loop with a variable gain.
Claim 10
Independent Claim
125 words
A method of optical recording and reproduction including the steps of directing a light spot toward a recording medium, modulating the intensity of said light spot according to writing pulses to record information on said recording medium, and detecting light reflected from said recording medium to reproduce information from said recording medium, said method comprising the step of carrying out a tracking servo operation on the basis of an electrical signal detected from said reflected light and including applying extracting pulses having a pulse width at least equal to that of said writing pulses so that time-wise portions of said electrical signal corresponding to the writing pulses during recording of information are not utilized for the tracking servo operation when the extracting pulses are present.
Claim 11
Independent Claim
125 words
A method of optical recording and reproduction including the steps of directing a light spot toward a recording medium, modulating the intensity of said light spot according to writing pulses to record information on said recording medium, and detecting light reflected from said recording medium to reproduce information from said recording medium, said method comprising the step of carrying out a tracking servo operation on the basis of an electrical signal detected from said reflected light and including applying extracting pulses having a pulse width at least equal to that of said writing pulses so that time-wise portions of said electrical signal corresponding to the writing pulses during recording of information are not utilized for the tracking servo operation when the extracting pulses are present.
Claim 12
Dependent Claim
38 words
A method of optical recording and reproduction according to claim 8, wherein the pulse width of said extracting pulses is determined while taking into account the frequency characteristics of a tracking servo signal of said tracking servo operation.
Claim 13
Dependent Claim
36 words
A method of optical recording and reproduction according to claim 8, wherein the gain of a circuit carrying out said tracking servo operation is changed over depending on whether information is to be recorded or reproduced.
Claim 14
Dependent Claim
46 words
A method of optical recording and reproduction according to claim 8, wherein the applying of extracting pulses includes applying the extracting pulses at a timing corresponding to a timing of the writing pulses, the tracking servo operation providing a tracking servo loop with a variable gain.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-04-14 | 1995-10-14 | 1996-04-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-04-14 | 1999-10-14 | 2000-04-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-04-14 | 2003-10-14 | 2004-04-14 | $7700.00 | Window Closed / Lapsed |