EP0393719A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Signal reproducing apparatus for optical recording and reproducing equipment and method for the same
Assignee: NEC Corp
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Filing: 1990-04-23
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Granted: —
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Expires: 2010-04-23
Abstract
Abstract The apparatus and method is used for recording optical information on an optical disk and reproducing the optical information therefrom by the use of an optical beam. The system is especially adapted to eliminate crosstalk from nearby tracks even when the position of the beam spot fluctuates with respect to a desired track and even when the size of a beam spot incident to the desired track is varied. The apparatus particularly comprises a frequency characteristic converter which receives output signals from a photodetector array (11). The photodetector array (11), for example, comprises 3 photodetectors (100, 101, 102) receiving input beams (130, 131 and 132). The photodetector (100) is associated with a desired track for reproducing a signal, whereas photodetectors (101, 102) are associated with neighbouring tracks for reproducing a replica of crosstalk. The frequency characteristic convertor (12) further comprises transversal filter means (110, 111, 112), each capable of controlling a frequency characteristic, an adder (120), a reference signal generator (121), an error detector (122), a filter control circuit (123) for controlling the filters (110, 111, 112), a timing control circuit (124), a decision circuit (125), a switch (126) and an output terminal (133). The output of the photodetector (100) adapted to reproduce a signal is fed to the timing control circuit (124), which detects the beginning of a preamble signal written in the track beforehand and delivers a control signal to the reference signal generator (121) and switch (126). When the timing control circuit (124) detects the end of the preamble signal, it delivers a control signal to the reference signal generator (121) and switch (126). The characteristic control for the transversal filters (110, 111, 112) is sequentially performed on the basis of the preamble signal and the corresponding reference signal and on the basis of an input signal and an output signal of the decision circuit (125).
Inventors
- 👤 Yutaka Hirose
- 👤 Yutaka Yamanaka
- 👤 Kazuhiro Okanoue
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:41
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/13; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10515; G11B11/10532; G11B11/10541; G11B11/10543; G11B11/10595; G11B7/004; G11B7/005; G11B7/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
136 words
A signal reproducing apparatus for use in combination with an optical source for emitting a plurality of light beams directed to successive first and second tracks on a recording medium and a photodetector for receiving reflections of said light beams from said successive first and second tracks on said recording medium and for producing first and second signals, said signal reproducing apparatus comprising: a plurality of characteristic converting means respectively receiving said first and second signals for varying frequency characteristics of said first and second signals to produce a first and second characteristic-converted signals; signal processing means for combining said first characteristic-converted signal and said second characteristic-converted signal to deliver a reproduced signal; and characteristic control means for controlling a frequency characteristic of a said plurality of characteristic converting means in accordance with said reproduced signal.
Claim 2
Dependent Claim
136 words
A signal reproducing apparatus for use in combination with an optical source for emitting a plurality of light beams directed to successive first and second tracks on a recording medium and a photodetector for receiving reflections of said light beams from said successive first and second tracks on said recording medium and for producing first and second signals, said signal reproducing apparatus comprising: a plurality of characteristic converting means respectively receiving said first and second signals for varying frequency characteristics of said first and second signals to produce a first and second characteristic-converted signals; signal processing means for combining said first characteristic-converted signal and said second characteristic-converted signal to deliver a reproduced signal; and characteristic control means for controlling a frequency characteristic of a said plurality of characteristic converting means in accordance with said reproduced signal.
Claim 3
Dependent Claim
20 words
A signal reproducing apparatus as claimed in claim 1, wherein said characteristic converting means is constructed by a transversal filter.
Claim 4
Dependent Claim
47 words
A signal reproducing apparatus as claimed in claim 1 or 2, wherein predetermined preamble signals are recorded in said successive first and second tracks on the recording medium; and said characteristic control means operates in response to detection of the preamble signal contained in said reproduced signal.
Claim 5
Dependent Claim
67 words
A signal reproducing apparatus as claimed in any of claims 1 to 3 wherein said characteristic control means includes means for delivering a reference signal corresponding to the preamble signal associated with said center track; means for detecting an error between said reference signal and the preamble signal contained in said reproduced signal; means for controlling tap coefficients in said transversal filter in response to said error.
Claim 6
Dependent Claim
67 words
A signal reproducing apparatus as claimed in any of claims 2 to 4 further comprising decision means receiving said reproduced signal for delivering a binary signal representative of information recorded in said center track, wherein said characteristic control means includes means for an error between said reproduced signal and said binary signal, and means for controlling tap coefficients in said transversal filter in response to said error.
Claim 7
Dependent Claim
148 words
A signal reproducing method for an optical recording and reproducing system which uses an optical head for emitting a light beam onto successive adjacent tracks on a recording disk and delivering a first signal from a first track storing information to be reproduced and a second signal from a second track adjacent to said first track, said first and second tracks corresponding to said successive adjacent tracks, comprising: filtering said first signal by a first transversal filter to produce a first filtered signal; filtering said second signal by a second transversal filter to produce a second filtered signal; adding said first and second filtered signals to an added signal; binarizing said added signal into a binary signal representative of said information; comparing said binary signal with said added signal to produce an error; and controlling characteristics of said first and second transversal filters in response to said error.
Claim 8
Dependent Claim
148 words
A signal reproducing method for an optical recording and reproducing system which uses an optical head for emitting a light beam onto successive adjacent tracks on a recording disk and delivering a first signal from a first track storing information to be reproduced and a second signal from a second track adjacent to said first track, said first and second tracks corresponding to said successive adjacent tracks, comprising: filtering said first signal by a first transversal filter to produce a first filtered signal; filtering said second signal by a second transversal filter to produce a second filtered signal; adding said first and second filtered signals to an added signal; binarizing said added signal into a binary signal representative of said information; comparing said binary signal with said added signal to produce an error; and controlling characteristics of said first and second transversal filters in response to said error.
Claim 9
Dependent Claim
148 words
A signal reproducing method for an optical recording and reproducing system which uses an optical head for emitting a light beam onto successive adjacent tracks including a center track and a side track and delivering a first signal from said center track and a second signal from said side track, said center and side tracks storing respective preamble signals, comprising: filtering said first signal by a first transversal filter to produce a first filtered signal; filtering said second signal by a second transversal filter to produce a second filtered signal; adding said first and second filtered signals to produce an added signal; generating a reference signal corresponding to the preamble signal stored in said center track; comparing a picked-up preamble signal contained said added signal with said reference signal to produce an error; and controlling characteristics of said first and second transversal filters in accordance with said error.
Claim 10
Dependent Claim
148 words
A signal reproducing method for an optical recording and reproducing system which uses an optical head for emitting a light beam onto successive adjacent tracks including a center track and a side track and delivering a first signal from said center track and a second signal from said side track, said center and side tracks storing respective preamble signals, comprising: filtering said first signal by a first transversal filter to produce a first filtered signal; filtering said second signal by a second transversal filter to produce a second filtered signal; adding said first and second filtered signals to produce an added signal; generating a reference signal corresponding to the preamble signal stored in said center track; comparing a picked-up preamble signal contained said added signal with said reference signal to produce an error; and controlling characteristics of said first and second transversal filters in accordance with said error.
Claim 11
Dependent Claim
223 words
A signal reproducing apparatus for optical recording and reproducing system which uses an optical head for emitting a plurality of light beams onto different tracks on a recording medium and having a plurality of photodetectors for producing first and second signals corresponding to reflections from said tracks independently of each other, said apparatus comprising: frequency characteristic converters each of varying a frequency characteristic of respective one of reproducing signals from said photodetectors independently of each other; combining means for combining outputs of said frequency characteristic converters; deciding means for executing decision of a signal state on an output of said combining means; preamble signal detecting means for detecting a preamble signal out of an output of said predetermined frequency characteristic converter; reference signal outputting means for outputting a reference signal in response to an output of said preamble signal detecting means; switch means coupled to said reference signal outputting means and said deciding means for delivering the reference signal when said preamble signal detecting means detects the preamble signal and an output of said deciding means when said preamble signal detecting means does not detect the preamble signal; error signal outputting means for detecting an error signal out of an output of said switch means and an output of said combining means; and control means for controlling characteristics of said frequency characteristic converters.
Claim 12
Dependent Claim
223 words
A signal reproducing apparatus for optical recording and reproducing system which uses an optical head for emitting a plurality of light beams onto different tracks on a recording medium and having a plurality of photodetectors for producing first and second signals corresponding to reflections from said tracks independently of each other, said apparatus comprising: frequency characteristic converters each of varying a frequency characteristic of respective one of reproducing signals from said photodetectors independently of each other; combining means for combining outputs of said frequency characteristic converters; deciding means for executing decision of a signal state on an output of said combining means; preamble signal detecting means for detecting a preamble signal out of an output of said predetermined frequency characteristic converter; reference signal outputting means for outputting a reference signal in response to an output of said preamble signal detecting means; switch means coupled to said reference signal outputting means and said deciding means for delivering the reference signal when said preamble signal detecting means detects the preamble signal and an output of said deciding means when said preamble signal detecting means does not detect the preamble signal; error signal outputting means for detecting an error signal out of an output of said switch means and an output of said combining means; and control means for controlling characteristics of said frequency characteristic converters.
References Cited (Backward Citations)
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