Servo Processor Receiving Photodetector Signals

• US 20160140995A1
• Filed: 01/21/2016
• Published: 05/19/2016
• Est. Priority Date: 01/25/2001
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Optical Devices, LLC (OD Management Partners, LLC)
• Inventors: Kadlec, Ron J.
• Granted Patent: US 9,514,777 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G11B 20/10046 filtering or equalising, e.g. setting the tap weights of an FIR filter
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: G11B 7/08505 Methods for track change, selection or preliminary positioning by moving the head
• CPC Class Codes: G11B 7/08529 Methods and circuits to control the velocity of the head as it traverses the tracks
• CPC Class Codes: G11B 7/08541 involving track counting to determine position
• CPC Class Codes: G11B 7/0901 for track following only G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence
• CPC Class Codes: G11B 7/0908 for focusing only G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence
• CPC Class Codes: G11B 7/0917 Focus-error methods other than those covered by G11B7/0909 - G11B7/0916
• CPC Class Codes: G11B 7/094 Methods and circuits for servo offset compensation
• CPC Class Codes: G11B 7/0941 Methods and circuits for servo gain or phase compensation during operation for initialising servos G11B7/0945
• CPC Class Codes: G11B 7/0945 Methods for initialising servos, start-up sequences

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 photodetector output signals resulting from an illumination of an optical disk are received. Versions of the photodetector signals are digitized to produce digital signals. A focus control signal is determined through at least one servo algorithm executed by a digital signal processor based on a focus error determined from the digital signals. Alternatively, a tracking control signal is determined through at least one servo algorithm executed by the digital signal processor based on a tracking error determined from the digital signals. The digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor

Claims

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 photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a focus control signal based on a focus error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

7. The digital servo method of claim 1, comprising:

driving a focus actuator based on the focus control signal.

2. 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 photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a tracking control signal based on a tracking error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

3. A digital servo method for an optical disk drive, comprising:

controlling functions of the optical disk drive with a microprocessor;

low-pass filtering and gain-adjusting versions of photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a focus control signal based on a focus error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

4. The digital servo method of claim 3, comprising:

adjusting one or more gain values for gain-adjusting one or more versions of the photodetector output signals based on a calculation performed by the digital signal processor.

5. The digital servo method of claim 3, comprising:

determining, by the digital signal processor, one or more gain values for gain-adjusting one or more versions of the photodetector output signals.

6. The digital servo method of claim 5, comprising:

gain-adjusting the one or more versions of the photodetector output signals based on the determined one or more gain values.

8. A digital servo method for an optical disk drive, comprising:

controlling functions of the optical disk drive with a microprocessor;

low-pass filtering and gain-adjusting versions of photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a tracking control signal based on a tracking error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

9. The digital servo method of claim 8, comprising:

adjusting one or more gain values for gain-adjusting one or more versions of the photodetector output signals based on a calculation performed by the digital signal processor.

10. The digital servo method of claim 8, comprising:

determining, by the digital signal processor, one or more gain values for gain-adjusting one or more versions of the photodetector output signals.

11. The digital servo method of claim 10, comprising:

gain-adjusting the one or more versions of the photodetector output signals based on the determined one or more gain values.

12. The digital servo method of claim 8, comprising:

driving a tracking actuator based on the tracking control signal.

13. 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 photodetector output signals into at least one digital signal; and

a digital signal processor configured to determine a focus error from the at least one digital signal and to determine, through at least one servo algorithm executed by the digital signal processor, a focus control signal from the focus error, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

14. 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 photodetector output signals into at least one digital signal; and

a digital signal processor configured to determine 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, a tracking control signal from the tracking error, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

15. An optical disk drive, comprising:

a microprocessor configured to perform control functions of the optical disk drive;

at least one low pass filter;

at least one amplifier;

an analog-to-digital converter configured to convert, into at least one digital signal, versions of photodetector output signals low-pass filtered by the at least one low pass filter and gain-adjusted by the at least one amplifier; and

a digital signal processor configured to determine a focus error from the at least one digital signal and to determine, through at least one servo algorithm executed by a digital signal processor, a focus control signal from the focus error, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

16. The optical disk drive of claim 15, wherein the digital signal processor is configured to determine one or more gain values for gain-adjusting one or more versions of the photodetector output signals.

17. The optical disk drive of claim 15, comprising:

a plurality of photodetectors configured to provide, to the digital signal processor, photodetector output signals resulting from an illumination of an optical disk.

18. The optical disk drive of claim 15, 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.

19. An optical disk drive, comprising:

a microprocessor configured to perform control functions of the optical disk drive;

at least one low pass filter;

at least one amplifier;

an analog-to-digital converter configured to convert, into at least one digital signal, versions of photodetector output signals low-pass filtered by the at least one low pass filter and gain-adjusted by the at least one amplifier; and

a digital signal processor configured to determine a tracking error from the at least one digital signal and to determine, through at least one servo algorithm executed by a digital signal processor, a tracking control signal from the tracking error, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

20. The optical disk drive of claim 19, wherein the digital signal processor is configured to determine one or more gain values for gain-adjusting one or more versions of the photodetector output signals.

21. The optical disk drive of claim 19, comprising:

a plurality of photodetectors configured to provide, to the digital signal processor, photodetector output signals resulting from an illumination of an optical disk.

22. The optical disk drive of claim 19, 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.

23. 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 photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a focus control signal based on a focus error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

24. 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 photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a tracking control signal based on a tracking error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

25. 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;

receiving low-pass filtered and gain-adjusted versions of photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a focus control signal based on a focus error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

26. The computer program of claim 25, comprising executable instructions for:

adjusting one or more gain values for gain-adjusting one or more versions of the photodetector output signals based on a calculation performed by the digital signal processor.

27. The computer program of claim 25, comprising executable instructions for:

determining, by the digital signal processor, one or more gain values for gain-adjusting one or more versions of the photodetector output signals.

28. The computer program of claim 27, comprising executable instructions for:

gain-adjusting the one or more versions of the photodetector output signals based on the determined one or more gain values.

29. The computer program of claim 25, comprising executable instructions for:

driving a focus actuator based on the focus control signal.

30. 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;

receiving low-pass filtered and gain-adjusted versions of photodetector output signals resulting from an illumination of an optical disk;

digitizing versions of the photodetector signals to produce digital signals; and

determining, through at least one servo algorithm executed by a digital signal processor, a tracking control signal based on a tracking error determined from the digital signals, wherein the digital signal processor has a specialized structure and arrangement for processing digital signals at a higher speed than the microprocessor.

31. The computer program of claim 30, comprising executable instructions for:

adjusting one or more gain values for gain-adjusting one or more versions of the photodetector output signals based on a calculation performed by the digital signal processor.

32. The computer program of claim 30, comprising executable instructions for:

determining, by the digital signal processor, one or more gain values for gain-adjusting one or more versions of the photodetector output signals.

33. The computer program of claim 32, comprising executable instructions for:

gain-adjusting the one or more versions of the photodetector output signals based on the determined one or more gain values.

34. The computer program of claim 30, comprising executable instructions for:

driving a tracking actuator based on the tracking control signal.