Disk apparatus and method of generating a tracking error signal
First Claim
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1. A disk apparatus which reproduces information by irradiating an optical beam to a disk, the disk apparatus comprising:
- a photodetector which comprises two or more photodetection cells, receives a reflected light from a disk, and outputs a photodetection signal based on the received reflected light;
a first tracking error signal generator which detects a phase difference between the photodetection signals from the photodetector, and generates a first tracking error signal corresponding to the phase difference;
a first variable amplifier which varies an amplitude of the first tracking error signal;
a second tracking error signal generator which detects a level difference between the photodetection signals from the photodetector; and
generates from the photodetection signal a second tracking error signal corresponding to the level difference;
a second variable amplifier which varies an amplitude of the second tracking error signal;
an adder which adds the first and second tracking error signals generated by the first and second variable amplifiers to provide an added tracking error signal;
a muting unit which mutes the first tracking error signal when the first tracking error signal amplitude is lower than a predetermined reference, and mutes the second tracking error signal when the second tracking error signal amplitude is lower than a predetermined reference; and
a tracking control unit which controls tracking by using the added error signal provided from the adder.
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Abstract
Comparators compare the amplitudes of a DPD tracking error signal indicating the phase difference between the detection signals supplied from a photodetector, and a PP tracking error signal indicating the level difference between the detection signals with the reference values, respectively. A gain control amplifier mutes a tracking error signal with the maximum amplitude smaller than a reference value.
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Citations
2 Claims
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1. A disk apparatus which reproduces information by irradiating an optical beam to a disk, the disk apparatus comprising:
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a photodetector which comprises two or more photodetection cells, receives a reflected light from a disk, and outputs a photodetection signal based on the received reflected light; a first tracking error signal generator which detects a phase difference between the photodetection signals from the photodetector, and generates a first tracking error signal corresponding to the phase difference; a first variable amplifier which varies an amplitude of the first tracking error signal; a second tracking error signal generator which detects a level difference between the photodetection signals from the photodetector; and
generates from the photodetection signal a second tracking error signal corresponding to the level difference;a second variable amplifier which varies an amplitude of the second tracking error signal; an adder which adds the first and second tracking error signals generated by the first and second variable amplifiers to provide an added tracking error signal; a muting unit which mutes the first tracking error signal when the first tracking error signal amplitude is lower than a predetermined reference, and mutes the second tracking error signal when the second tracking error signal amplitude is lower than a predetermined reference; and a tracking control unit which controls tracking by using the added error signal provided from the adder.
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2. A disk apparatus which reproduces information by irradiating an optical beam to a disk, the disk apparatus comprising:
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a photodetector which comprises two or more photodetection cells, receives a reflected light from a disk, and outputs a photodetection signal based on the received reflected light; a first tracking error signal generator which detects a phase difference between the photodetection signals from the photodetector, and generates a first tracking error signal corresponding to the phase difference; a first variable amplifier which varies an amplitude of the first tracking error signal; a second tracking error signal generator which detects a level difference between the photodetection signals from the photodetector, and generates from the photodetection signal a second tracking error signal corresponding to the level difference; a second variable amplifier which varies an amplitude of the second tracking error signal; an adder which adds the first and second tracking error signals generated by the first and second variable amplifiers, and provides an added tracking error signal; a muting unit which mutes one of the first and second tracking error signals when the amplitude of the one of the tracking error signals is lower than a predetermined reference; and a tracking control unit which controls tracking by using the added tracking error signal provided from the adder.
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Specification
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Current AssigneeKabushiki Kaisha Toshiba (Toshiba Corporation)
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Original AssigneeKabushiki Kaisha Toshiba (Toshiba Corporation)
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InventorsNakano, Takeshi, Nakane, Hiroshi
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Primary Examiner(s)Tran, Thang V.
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Assistant Examiner(s)HALEY, JOSEPH R
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Application NumberUS10/724,685Publication NumberTime in Patent Office1,442 DaysField of SearchNoneUS Class Current369/44.36CPC Class CodesG11B 2007/0006 adapted for scanning differ...G11B 7/0901 for track following only G1...G11B 7/0906 Differential phase differen...
