EP0148028A2
Expired / Lapsed
EP
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Optical information reproducing apparatus
Assignee: Sony Corp
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Filing: 1984-12-27
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Granted: —
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Expires: 2004-12-27
Abstract
Abstract An optical information reproducing apparatus for reproducing an information recorded on a recording surface of a disc shape record medium is disclosed, which includes an optical pick-up device mounted on a tiltable optical block and having a laser beam source for generating a laser beam and a photo detector for detecting the reflected beam from the recording surface and for reproducing the recorded information, a device for rotating the record medium, a skew error detector for detecting a skew of the record medium relative to the optical pick-up device and for generating a skew error signal having a D.C. component and an A.C. component, a control circuit supplied with the skew error signal and for generating a control signal responsive to the D.C. component of the skew error signal, a skew error corrector controlled by the control signal and for controlling the optical block so that the optical axis of the pick-up device is maintained to be always perpendicular to the recording surface. The above control circuit includes a comparator for comparing the level of the skew error signal with a threshold level and for generating an output pulse, the width of which corresponds to the D.C. component of the skew error signal, and a pulse width discriminator for discriminating the width of the output pulse relative to a reference pulse corresponding to a rotating period of the record medium.
Inventors
- 👤 Toru Ohtsuka Kanagawa
- 👤 Tadashi Motoyama Kanagawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:26
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/095; G11B7/0956
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
228 words
An optical information reproducing apparatus for reproducing an information recorded on a recording surface of a disc shape record medium comprising: an optical pick-up device mounted on a tiltable optical block, and having a laser beam source for generating a laser beam and a photo detector for detecting a reflected beam from said recording surface and for reproducing the recorded information; means for rotating said record medium; a skew error detector for detecting a skew of the record medium relative to said optical pick-up device and for generating a skew error signal having a D.C. component and an A.C. component; a control circuit supplied with the skew error signal and for generating a control signal responsive to the D.C. component of said skew error signal; and a skew error corrector controlled by the control signal and for controlling said optical block so that the optical axis of said pick-up device is maintained to be perpendicular to the recording surface, wherein said control circuit includes a comparator for comparing the level of said skew error signal and a threshold level and for generating an output pulse, the width of which corresponds to the D.C. component of the skew error signal, and a pulse width discriminator for discriminating the width of said output pulse relative to a reference pulse correspond- in g to a rotating period of said record medium.
Claim 2
Dependent Claim
228 words
An optical information reproducing apparatus for reproducing an information recorded on a recording surface of a disc shape record medium comprising: an optical pick-up device mounted on a tiltable optical block, and having a laser beam source for generating a laser beam and a photo detector for detecting a reflected beam from said recording surface and for reproducing the recorded information; means for rotating said record medium; a skew error detector for detecting a skew of the record medium relative to said optical pick-up device and for generating a skew error signal having a D.C. component and an A.C. component; a control circuit supplied with the skew error signal and for generating a control signal responsive to the D.C. component of said skew error signal; and a skew error corrector controlled by the control signal and for controlling said optical block so that the optical axis of said pick-up device is maintained to be perpendicular to the recording surface, wherein said control circuit includes a comparator for comparing the level of said skew error signal and a threshold level and for generating an output pulse, the width of which corresponds to the D.C. component of the skew error signal, and a pulse width discriminator for discriminating the width of said output pulse relative to a reference pulse correspond- in g to a rotating period of said record medium.
Claim 3
Dependent Claim
67 words
An optical information reproducing apparatus according to claim 1, wherein said comparator includes a pair of level ccnparing circuits for comparing the level of said skew error signal and upper and lower threshold levels and for generating a pair of output pulses respectively, and said pulse width discriminator discriminates the width of said pair of output pulses and generates the control signal for said skew error corrector.
Claim 4
Dependent Claim
66 words
An optical information reproducing apparatus according to claim 1, wherein said pulse width discriminator includes counter means, said output pulse being applied to said counter means as a count enable pulse and an FG pulse cf said rotating means being applied to said counter means as a count pulse and latch means for latching an MSB (most significant bit) of the output of said counter means.
Claim 5
Dependent Claim
46 words
An optical information reproducing apparatus according to claim 3, wherein said skew error corrector includes a motor for rotating said optical block, the output of said latch means being supplied to a switch through which a uni-directional and constant control signal is supplied to said motor.
Claim 6
Dependent Claim
22 words
An optical information reproducing apparatus according to claim 3, wherein said counter is cleared at every rotating period of said record medium.
Claim 7
Dependent Claim
111 words
An optical information reproducing apparatus according to claim 1, wherein said pulse width discriminatcr includes first counter means, said output pulse being applied to said first counter means as a ccunt enable pulse and the FG pulse of said rotating means being applied to said counter means as a count pulse, second counter means, the output of said first counter means being leaded to said second counter means at every rotating period of said record medium, delay means for delaying said output pulse for one rotating period of said record medium, and a comparator for comparing the input and output of said delay means and for controlling said second counter means.
Claim 8
Dependent Claim
31 words
An optical information reproducing apparatus according to claim 6, wherein the MSB of the output of said second counter means is supplied to said skew error corrector as a control signal.
Claim 9
Dependent Claim
31 words
An optical information reproducing apparatus according to claim 7, wherein said delay means includes a shift register, and said FG pulse is supplied to said shift register as a clock pulse.
Claim 10
Dependent Claim
58 words
An optical information reproducing apparatus according to claim 8, wherein said comparator includes an exclusive OR gate, the input and output of said shift register being supplied to inputs of said gate, and the output of said exclusive OR gate is supplied to said second counter means to which said FG pulse is supplied as a count pulse.
Claim 11
Dependent Claim
30 words
An optical information reproducing apparatus according to claim 9, wherein said output pulse is supplied to said second counter means as a control signal fcr controlling the count direction thereof.
References Cited (Backward Citations)
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