Servo processor receiving photodetector signals

• US 9,105,281 B2
• Filed: 04/01/2013
• Issued: 08/11/2015
• Est. Priority Date: 01/25/2001
• Status: Expired due to Fees

• Current Assignee: RPX Corporation
• Original Assignee: Optical Devices, LLC (OD Management Partners, LLC)
• Inventors: Kadlec, Ron J.
• Primary Examiner(s): Dinh, Tan X
• Application Number:
  US13/854,475
• Publication Number:
  US 20130272105A1
• Time in Patent Office: 862 Days
• Field of Search: 369 301- 3011, 369 3013- 3018, 369/44.28, 369/44.27, 369/44.29, 369/44.35
• 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

A servo processor for an optical disk drive is provided that includes: an analog-to-digital converter for converting versions of photodetector output signals into digital signals; and a digital signal processor configured to receive the digital signals, the digital signal processor being further configured to determine a focus error signal (FES) and a tracking error signal (TES) from the digital signals, the digital signal processor being further configured to process TES and FES through servo algorithms to produce tracking and focus control signals.

Claims

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

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 servo algorithms in 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.

2. The digital servo method of claim 1, 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.

3. 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:

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 servo algorithms in 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.

4. A method, comprising:

providing, to a digital signal processor, photodetector output signals resulting from an illumination of an optical disk;

receiving, from the digital signal processor, at least one of a tracking control signal and a focus control signal determined by the digital signal processor from low-pass filtered and gain-adjusted versions of the photodetector output signals; and

driving at least one of a tracking actuator based on the tracking control signal and a focus actuator based on the focus control signal.

6. The optical disk drive of claim 4, 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.

5. An optical disk drive, comprising:

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 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.

7. An optical disk drive, comprising:

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

a driver configured to receive, from the digital signal processor, at least one of a tracking control signal and a focus control signal determined by the digital signal processor from low-pass filtered and gain-adjusted versions of the photodetector output signals and to drive at least one of a tracking actuator based on the tracking control signal and a focus actuator based on the focus control signal.