Patent EP0183435A2 successfully refreshed from Google Patents.
EP0183435A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Focus servo device
Assignee: Pioneer Corp
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Filing: 1985-11-13
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Granted: —
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Expires: 2005-11-13
Abstract
Abstract A focus servo device for an apparatus for reproducing recorded information which includes a pickup for reproducing information recorded on a recording disk and a tracking servo device for maintaining the pickup over a recorded track on the disk, has means (53) in which loop gain is reduced in response to detected abnormalities (22) in a recording disk, in order to prevent interference with a tracking servo device in an optical disk player.
Inventors
- 👤 Junichi C/O Pioneer Electronic Corporation Yoshio
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:38
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0948; G11B7/0941; G11B7/0901; G11B7/0903; G11B7/0908
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
153 words
A focus servo device for an apparatus for reproducing recorded information which includes a pickup for reproducing information recorded on a recording disk and a tracking servo device for Maintaining the pickup over a recorded track on the disk, the focus servo device having a spotlight irradiated from the pickup controlled in accordance with a focus error signal so as to correctly converge the spotlight onto the recording surface of the disk, characterised by an abnormality detecting means (22) for detecting abnormalities on the recording surface in accordance with the level of an output signal of the pickup, and gain setting means (53) for setting the gain of a servo loop, the gain setting means reducing the loop gain in a predetermined frequency band within a servo zone in response to a detected output from the abnormality detecting means (22), whereby the focus servo device prevents abnormalities from affecting the tracking servo device.
Claim 2
Dependent Claim
153 words
A focus servo device for an apparatus for reproducing recorded information which includes a pickup for reproducing information recorded on a recording disk and a tracking servo device for Maintaining the pickup over a recorded track on the disk, the focus servo device having a spotlight irradiated from the pickup controlled in accordance with a focus error signal so as to correctly converge the spotlight onto the recording surface of the disk, characterised by an abnormality detecting means (22) for detecting abnormalities on the recording surface in accordance with the level of an output signal of the pickup, and gain setting means (53) for setting the gain of a servo loop, the gain setting means reducing the loop gain in a predetermined frequency band within a servo zone in response to a detected output from the abnormality detecting means (22), whereby the focus servo device prevents abnormalities from affecting the tracking servo device.
Claim 3
Dependent Claim
53 words
A device according to claim 1, further comprising phase compensating means (70) for performing phase compensation of the focus error signal, the phase compensating means changing over a compensating band in accordance with the band where the loop gain is reduced by the gain setting means (53) in response to the detected output.
Claim 4
Dependent Claim
92 words
A device according to claim 1 or claim 2, wherein the pickup irradiates the recording surface of the recording disk with a single recorded-information detecting spotlight (1) and a pair of tracking information detecting spotlights (2,3) respectively preceding and following the single recorded-information detecting spotlight (1) when it moves relative to the recording disk, and wherein the abnormality detecting means (22) detects the abnormalities in accordance with the output signals of the preceding tracking information detecting spotlight and holds the detection output for a predetermined time after disappearance of the output signals.
Claim 5
Dependent Claim
44 words
A device according to claim 3, further comprising means (11,15,21) responsive to reflected outputs of the preceding and succeeding tracking information detecting spotlights, for outputting a tracking error signal, the abnormality detecting means producing a detection output in response to the tracking error signal.
Claim 6
Independent Claim
93 words
A device according to any one of claims 1 to 4, wherein the pickup further comprises transducer means (5) for receiving output from the single recorded-information detecting spotlight (1) output from the single recorded-information detecting spotlight (1) and outputting a first signal, and RF means (71) for converting the first signal to an RF signal; envelope detecting means (72) for detecting an envelope of the RF signal; and waveform shaping means (73) for converting the envelope to a shaped output, the abnormality detecting means (22) detecting abnormalities in accordance with the shaped output.
References Cited (Backward Citations)
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