Servo processor receiving photodetector signals
AssigneeOptical Devices, LLC
InventorRon J. Kadlec
Life of this patent
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Abstract
A focus servo system for an optical disk drive includes an optical pick-up unit comprising at least one photodetector. At least one analog to digital converter is configured to digitize signals received from the at least one photodetector. At least one processor is configured to execute a digital servo algorithm to process the versions of the digitized signals to calculate a focus error signal (FES) from the versions of the digitized signals and to indicate a focus open condition based on the FES and the versions of the digitized signals.
Claims23
A focus servo system for an optical disk drive, the focus servo system comprising:
- an optical pick-up unit comprising at least one photodetector;
- at least one analog to digital converter configured to digitize signals received from the at least one photodetector;
- and
- at least one processor configured to execute a digital servo algorithm to process the versions of the digitized signals to:
- calculate a focus error signal (FES) from the versions of the digitized signals;
- apply an FES gain to the FES to provide a modified FES signal;
- obtain a threshold value based upon the modified FES signal;
- compute a sum signal from the versions of the digitized signals;
- determine if the sum signal is below the threshold value;
- and
- indicate a focus open condition if the sum signal is below the threshold value.
A focus servo system for an optical disk drive, the focus servo system comprising:
- an optical pick-up unit comprising at least one photodetector;
- at least one analog to digital converter configured to digitize signals received from the at least one photodetector;
- and
- at least one processor configured to execute a digital servo algorithm to process the versions of the digitized signals to calculate a focus error signal (FES) from the versions of the digitized signals and indicate a focus open condition based on the FES and the versions of the digitized signals.
A digital servo method for an optical disk drive, comprising:
- digitizing versions of photodetector signals received from an optical pick-up unit of the optical disk drive to produce digital signals;
- determining, through servo algorithms in a digital signal processor, a focus error signal from the digital signals;
- and
- determining a focus open condition based on the focus error signal and versions of the digitized signals.
A non-transitory computer readable medium storing a computer program, executable by a machine, for a digital servo method for an optical disk drive, the computer program comprising executable instructions for:
- digitizing versions of the photodetector signals to produce digital signals;
- determining, through servo algorithms in a digital signal processor, a focus error signal from the digital signals;
- and
- determining a focus open condition based on the focus error signal and versions of the digitized signals.
Dependencies are inferred from the claim text.