US5959953A
Expired / Lapsed
US
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Methods and apparatus for performing cross-talk correction in a multi-track optical disk reader based on magnification error
Assignee: Xylon LLC
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Filing: 1998-03-12
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Granted: 1999-09-28
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Expires: 2018-03-12
Abstract
Abstract An optical pickup assembly for a multitrack optical disk reader includes a multi-element photodetector onto which a plurality of reflected track images are projected. Circuitry is provided for detecting a magnification error, and for generating a magnification error correction signal to correct or compensate for the magnification error. Circuitry is also provided for correcting for cross-talk components in the output signals of the multi-element photodetector responsive to the detected magnification error.
Inventors
- 👤 Amir Alon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:55
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0943; G11B7/12; G11B7/13; G11B7/131; G11B7/135; G11B7/1356; G11B7/1395; G11B7/14; G11B7/004; G11B7/005
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
160 words
Apparatus for simultaneously reading multiple adjacent tracks of an optical disk, the apparatus comprising: means for generating an array of reading beams including a center beam and a plurality of side beams, each side beam having a radial location in the array; an optical system disposed in a path of the array of reading beams, the optical system directing the array of reading beams onto multiple adjacent tracks of the optical disk; a plurality of photodetector elements including a center element and a plurality of side elements, the center element generating an output signal corresponding to the center beam, each one of the plurality of side elements generating an output signal for a corresponding one of the plurality of side beams; means for detecting a magnification error; and means for correcting the output signal of at least one of the plurality of side elements responsive to the magnification error and the radial location of the side beam in the array.
Claim 2
Dependent Claim
160 words
Apparatus for simultaneously reading multiple adjacent tracks of an optical disk, the apparatus comprising: means for generating an array of reading beams including a center beam and a plurality of side beams, each side beam having a radial location in the array; an optical system disposed in a path of the array of reading beams, the optical system directing the array of reading beams onto multiple adjacent tracks of the optical disk; a plurality of photodetector elements including a center element and a plurality of side elements, the center element generating an output signal corresponding to the center beam, each one of the plurality of side elements generating an output signal for a corresponding one of the plurality of side beams; means for detecting a magnification error; and means for correcting the output signal of at least one of the plurality of side elements responsive to the magnification error and the radial location of the side beam in the array.
Claim 3
Dependent Claim
48 words
The apparatus of claim 1 wherein the output signal of the at least one of the plurality of side elements comprises a cross-talk component for an adjacent one of the plurality of reading beams and the means for correcting corrects the output signal to reduce the cross-talk component.
Claim 4
Dependent Claim
37 words
The apparatus of claim 1 wherein two of the plurality of photodetector elements comprise split photodetector elements and the means for detecting the magnification error comprises circuitry for comparing output signals generated by the split photodetector elements.
Claim 5
Dependent Claim
30 words
The apparatus of claim 1 wherein the means for detecting the magnification error generates a lookup table containing values of magnification error correlated to radial location on the optical disk.
Claim 6
Dependent Claim
29 words
The apparatus of claim 4 wherein the lookup table is generated by comparing a computed track pitch to a nominal track pitch for a specified type of optical disk.
Claim 7
Dependent Claim
23 words
The apparatus of claim 4 wherein the lookup table is generated by analyzing jitter rates obtained when reading data from the optical disk.
Claim 8
Dependent Claim
44 words
The apparatus of claim 1 wherein the means for correcting the output signal of one of the side elements comprises circuitry for forming a weighted sum of the output signal and an output signal generated by an adjacent one of the plurality photodetector elements.
Claim 9
Dependent Claim
20 words
The apparatus of claim 7 wherein weights used in computing the weighted sum are determined responsive to the magnification error.
Claim 10
Dependent Claim
24 words
The apparatus of claim 8 wherein the weights are a function of a radial position of a track being read from the optical disk.
Claim 11
Dependent Claim
10 words
The apparatus of claim 8 wherein the weights are predetermined.
Claim 12
Dependent Claim
19 words
The apparatus of claim 8 wherein the weights are determined by measuring a track pitch of the optical disk.
Claim 13
Dependent Claim
44 words
The apparatus of claim 8 wherein the weights are determined by measuring an error rate in data being read from the optical disk while dithering the value of the weights, and selecting the value of the weights corresponding to a smallest measured error rate.
Claim 14
Dependent Claim
29 words
The apparatus of claim 1 wherein the center element comprises multiple divisions, the apparatus further comprising circuitry to compute a focus error signal using outputs of the multiple divisions.
Claim 15
Dependent Claim
37 words
The apparatus of claim 1 wherein at least two of the plurality of photodetector elements comprise split photodetector elements, the apparatus further comprising circuitry to compute a tracking error signal using outputs of the split photodetector elements.
Claim 16
Independent Claim
127 words
A method for simultaneously reading multiple data tracks from an optical disk, the method comprising: providing an array of reading beams including a center beam and a plurality of side beams, each side beam having a radial location in the array; providing a plurality of photodetector elements including a center element and a plurality of side elements, the center element generating an output signal corresponding to the center beam, each one of the plurality of side elements generating an output signal for a corresponding one of the plurality of side beams; generating a magnification error signal; correcting the output signal for at least one of the plurality of side elements responsive to the magnification error signal and the radial location of the side beam in the array.
Claim 17
Independent Claim
127 words
A method for simultaneously reading multiple data tracks from an optical disk, the method comprising: providing an array of reading beams including a center beam and a plurality of side beams, each side beam having a radial location in the array; providing a plurality of photodetector elements including a center element and a plurality of side elements, the center element generating an output signal corresponding to the center beam, each one of the plurality of side elements generating an output signal for a corresponding one of the plurality of side beams; generating a magnification error signal; correcting the output signal for at least one of the plurality of side elements responsive to the magnification error signal and the radial location of the side beam in the array.
Claim 18
Dependent Claim
40 words
The method of claim 15 wherein the output signal generated by the at least one side element includes a cross-talk component for an adjacent one of the plurality of reading beams and correcting the output signal reduces the cross-talk component.
Claim 19
Dependent Claim
33 words
The method of claim 15 wherein correcting the output signal comprises forming a weighted sum of the output signal and an output signal generated by an adjacent one of the plurality photodetector elements.
Claim 20
Dependent Claim
20 words
The method of claim 17 wherein correcting the output signal further comprises adjusting weights used in forming the weighted sum.
Claim 21
Dependent Claim
18 words
The method of claim 18 wherein adjusting the weights comprises measuring a track pitch of the optical disk.
Claim 22
Dependent Claim
38 words
The method of claim 18 wherein adjusting the weights comprises: analyzing an error rate in data signals generated by the plurality of photodetector elements; perturbating the weights; and selecting the perturbed weights corresponding to a smallest error rate.
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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) | 2002-09-27 | 2003-03-29 | 2003-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-27 | 2007-03-29 | 2007-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-27 | 2011-03-29 | 2011-09-28 | $7700.00 | Window Closed / Lapsed |