US4774698A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical disc recording and reproducing apparatus with improved servo control
Assignee: Sony Corp
•
Filing: 1985-12-05
•
Granted: 1988-09-27
•
Expires: 2005-12-05
Abstract
Abstract An optical disc recording and reproducing apparatus incorporates apparatus for recording a modulated signal on an optical disc, using a laser beam, and apparatus for optically reading a signal recorded on the disc. In both recording and reproducing modes, an optical signal is produced from the disc and used to supply a control signal to a servo system, for controlling the position of the laser beam relative to the optical disc. Apparatus is provided for subtracting, from the servo control signal, the low frequency components in the modulated signal being recorded on the disc, to improve the accuracy of focus and tracking of the laser beam relative to the optical disc.
Inventors
- 👤 Fumiaki Henmi
- 👤 Tamotsu Yamagami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:00
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B11/00; G11B11/10; G11B11/105; G11B11/10595; G11B11/10502; G11B11/10504; G11B11/10506; G11B11/1055; G11B11/10576; G11B7/0941
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
140 words
An optical disc recording and reproducing apparatus comprising: a digital modulating circuit supplied with a digital signal to be recorded; means for controlling a laser beam introduced from a laser light source to an optical disc in response to an output of said digital modulating circuit; first optical means for introducing the laser beam emitted from said laser light source to said optical disc; second optical means for introducing a laser beam returned from said optical disc to a photo detector; an actuator supplied with a servo error signal obtained from said photo detector and for adjusting said laser beam relative to said optical disc; a low pass filter supplied with the output of said digital modulating circuit; and removing means for removing from said servo error signal a low frequency component output signal derived from said low pass filter.
Claim 2
Dependent Claim
140 words
An optical disc recording and reproducing apparatus comprising: a digital modulating circuit supplied with a digital signal to be recorded; means for controlling a laser beam introduced from a laser light source to an optical disc in response to an output of said digital modulating circuit; first optical means for introducing the laser beam emitted from said laser light source to said optical disc; second optical means for introducing a laser beam returned from said optical disc to a photo detector; an actuator supplied with a servo error signal obtained from said photo detector and for adjusting said laser beam relative to said optical disc; a low pass filter supplied with the output of said digital modulating circuit; and removing means for removing from said servo error signal a low frequency component output signal derived from said low pass filter.
Claim 3
Dependent Claim
39 words
An optical disc recording and reproducing apparatus according to claim 1, characterized in that said removing means includes a gain adjusting circuit which adjusts a gain of said low frequency component output signal derived from said low pass filter.
Claim 4
Dependent Claim
48 words
An optical disc recording and reproducing apparatus according to claim 2, characterized in that said gain adjusting circuit inverts a polarity of said low frequency component output signal and said low frequency component signal with the polarity inverted is supplied to an adder included in said removing means.
Claim 5
Dependent Claim
33 words
An optical disc recording and reproducing apparatus according to claim 1, characterized in that said first optical means comprises apparatus for conducting upolarized light from said laser light source to said optical disc.
Claim 6
Dependent Claim
22 words
An optical disc recording and reproducing apparatus according to claim 4, characterized in that said optical disc is an optical magnetic disc.
References Cited (Backward Citations)
EP0035236A1
Cited
EP0078673A2
Cited
US4627040A
Cited
JPS59157877A
Cited
US4661942A
Cited
US4607157A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-27 | 1992-03-28 | 1992-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-27 | 1996-03-28 | 1996-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-27 | 2000-03-28 | 2000-09-27 | $7700.00 | Window Closed / Lapsed |