Servo Processor Receiving Photodetector Signals

Abstract

An optical disk drive and a digital servo method for the optical disk drive includes controlling functions of the optical disk drive with a microprocessor. Low-pass filtered and gain adjusted versions of individual photodetector output signals resulting from an illumination of an optical disk are received. Versions of the individual photodetector output signals are digitized to produce digital signals. A focus control signal and/or a tracking control signal is determined through at least one servo algorithm executed by a digital signal processor based on a focus error and/or tracking error, respectively, determined from the digital signals. The digital signal processor is an integrated circuit structured and arranged for manipulation of digital signals in accordance with programmed commands, and in a manner that operates faster than the microprocessor.

I claim: 
     
         1 . A digital servo method for an optical disk drive, comprising:
 controlling functions of the optical disk drive with a microprocessor;   receiving low-pass filtered and gain-adjusted versions of individual photodetector output signals resulting from an illumination of an optical disk;   digitizing versions of the individual photodetector output signals to produce digital signals; and   determining, through at least one servo algorithm executed by a digital signal processor, at least one of a tracking control signal based on a tracking error determined from the digital signals and a focus control signal based on a focus error determined from the digital signals, wherein the digital signal processor is an integrated circuit structured and arranged for manipulation of digital signals in accordance with programmed commands, and in a manner that operates faster than the microprocessor.   
     
     
         2 . The digital servo method of  claim 1 , comprising:
 adjusting one or more gain values for gain-adjusting one or more versions of the individual photodetector output signals based on a calculation performed by the digital signal processor.   
     
     
         3 . The digital servo method of  claim 1 , comprising:
 determining, by the digital signal processor, one or more gain values for gain-adjusting one or more versions of the individual photodetector output signals.   
     
     
         4 . The digital servo method of  claim 3 , comprising:
 gain-adjusting the one or more versions of the individual photodetector output signals based on the determined one or more gain values.   
     
     
         5 . The digital servo method of  claim 1 , comprising:
 driving a focus actuator based on the focus control signal.   
     
     
         6 . The digital servo method of  claim 1 , comprising:
 driving a tracking actuator based on the tracking control signal.   
     
     
         7 . An optical disk drive, comprising:
 a microprocessor configured to perform control functions of the optical disk drive;   an analog-to-digital converter configured to convert low-pass filtered and gain-adjusted versions of individual photodetector output signals into at least one digital signal; and   a digital signal processor configured to determine at least one of a focus error and a tracking error from the at least one digital signal and to determine, through at least one servo algorithm executed by the digital signal processor, at least one of a focus control signal from the focus error and a tracking control signal from the tracking error, wherein the digital signal processor is an integrated circuit structured and arranged for manipulation of digital signals in accordance with programmed commands, and in a manner that operates faster than the microprocessor.   
     
     
         8 . The optical disk drive of  claim 7 , wherein the digital signal processor is configured to determine one or more gain values for gain-adjusting one or more versions of the individual photodetector output signals. 
     
     
         9 . The digital servo method of  claim 8 , comprising:
 At least one amplifier for gain-adjusting the one or more versions of the individual photodetector output signals based on the determined one or more gain values.   
     
     
         10 . The optical disk drive of  claim 7 , comprising:
 a plurality of photodetectors configured to provide, to the digital signal processor, individual photodetector output signals resulting from an illumination of an optical disk.   
     
     
         11 . The optical disk drive of  claim 7 , comprising:
 a driver configured to receive, from the digital signal processor, the focus control signal and to drive a focus actuator based on the focus control signal.   
     
     
         12 . The optical disk drive of  claim 7 , comprising:
 a driver configured to receive, from the digital signal processor, the tracking control signal and to drive a tracking actuator based on the tracking control signal.   
     
     
         13 . 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:
 controlling functions of the optical disk drive with a microprocessor;   low-pass filtering and gain-adjusting versions of individual photodetector output signals resulting from an illumination of an optical disk;   digitizing versions of the individual photodetector output signals to produce digital signals; and   determining, through at least one servo algorithm executed by a digital signal processor, at least one of a tracking control signal based on a tracking error determined from the digital signals and a focus control signal based on a focus error determined from the digital signals, wherein the digital signal processor is an integrated circuit structured and arranged for manipulation of digital signals in accordance with programmed commands, and in a manner that operates faster than the microprocessor.   
     
     
         14 . The computer program of  claim 13 , comprising executable instructions for:
 adjusting one or more gain values for gain-adjusting one or more versions of the individual photodetector output signals based on a calculation performed by the digital signal processor.   
     
     
         15 . The computer program of  claim 13 , comprising executable instructions for:
 determining, by the digital signal processor, one or more gain values for gain-adjusting one or more versions of the individual photodetector output signals.   
     
     
         16 . The computer program of  claim 15 , comprising executable instructions for:
 gain-adjusting the one or more versions of the individual photodetector output signals based on the determined one or more gain values.   
     
     
         17 . The computer program of  claim 13 , comprising executable instructions for:
 driving a focus actuator based on the focus control signal.   
     
     
         18 . The computer program of  claim 13 , comprising executable instructions for:
 driving a tracking actuator based on the tracking control signal.