Claims
- 1. A method of calibrating a focus error signal gain in a focus servo system of an optical disk drive, comprising:
determining a focus sum threshold; determining a focus offset control effort which results in a sum signal at the focus sum threshold; providing a small sinusoidal control effort centered on the focus offset control effort; and adjusting the focus error signal gain in response to a focus error signal monitored while the small sinusoidal control effort is provided.
- 2. The method of claim 1, wherein the first location and the second location are the positions of the optical pick-up unit closest to an optical medium and furthest away from the optical medium.
- 3. The method of claim 1, wherein the sum signal is the sum of each of the signals from detectors in the optical pick-up unit.
- 4. The method of claim 1, wherein determining the focus sum threshold includes
oscillating the optical pick-up unit through a focus position; monitoring the sum signal while the optical pick-up unit is being oscillated; and setting the focus sum threshold to a fraction of a peak value of the sum signal.
- 5. The method of claim 1, wherein providing a small sinusoidal control effort includes
moving the optical pick-up unit to the focus offset control effort; and determining the small sinusoidal control effort to be a sum of the focus offset control effort and a sinusoidal function; and applying the small sinusoidal control effort to position the optical pick-up unit.
- 6. The method of claim 1, wherein determining the focus offset control effort includes
providing a control effort that oscillates the optical pick-up unit such that the sum signal oscillates through the focus sum threshold; setting the focus offset control effort to the control effort where the sum signal equals the focus sum threshold.
- 7. The method of claim 6, wherein setting the focus offset control effort includes averaging the control efforts where the sum signal equals the focus sum threshold over several oscillations of the optical pick-up unit.
- 8. The method of claim 1, wherein adjusting the focus error signal gain includes setting the focus error signal gain such that a peak-to-peak value of the focus error signal, measured while the small sinusoidal effort is being provided, is at a predetermined value.
- 9. The method of claim 8, further including determining an average focus error signal gain from determining the focus error signal gain a number of times and setting the focus error signal gain to an average focus error signal gain.
- 10. An optical disk drive, comprising:
an optical pick-up unit; an analog processor coupled to receive signals from detectors in the optical pick-up unit and provide digital signals; at least one processor coupled to receive the digital signals, the at least one processor calculating a focus control signal; and a driver coupled to control a focus position of the optical pick-up unit in response to the focus control signal, wherein the at least one processor executes an algorithm that
determines a focus sum threshold, determines a focus offset control effort which results in a sum signal at the focus sum threshold, provides a small sinusoidal control effort centered on the focus offset control effort, and adjusts the focus error signal gain in response to a focus error signal monitored while the small sinusoidal control effort is provided.
- 11. The drive of claim 10, wherein the first location and the second location are the positions of the optical pick-up unit closest to an optical medium and furthest away from the optical medium.
- 12. The drive of claim 10, wherein the sum signal is the sum of the digital signals from the optical pick-up unit.
- 13. The drive of claim 10, wherein the focus sum threshold is determined by
oscillating the optical pick-up unit between the first location and the second location; monitoring the sum signal while the optical pick-up unit is being oscillated; and setting the focus sum threshold to a fraction of a peak value of the sum signal.
- 14. The drive of claim 10, wherein the small sinusoidal control effort is provided by
moving the optical pick-up unit to the focus offset control effort; and determining the small sinusoidal control effort to be a sum of the focus offset control effort and a sinusoidal function; and applying the small sinusoidal control effort to position the optical pick-up unit.
- 15. The drive of claim 10, wherein the focus offset control effort is determined by
providing a control effort that oscillates the optical pick-up unit such that the sum signal oscillates through the focus sum threshold; setting the focus offset control effort to the control effort where the sum signal equals the focus sum threshold.
- 16. The drive of claim 15, wherein setting the focus offset control effort includes averaging the control efforts where the sum signal equals the focus sum threshold over several oscillations of the optical pick-up unit.
- 17. The drive of claim 10, wherein the focus error signal gain is adjusted by setting the focus error signal gain such that a peak-to-peak value of the focus error signal, measured while the small sinusoidal effort is being provided, is at a predetermined value.
- 18. The drive of claim 17, further including determining an average focus error signal gain from determining the focus error signal gain a number of times and setting the focus error signal gain to an average focus error signal gain.
- 19. An optical disk drive, comprising:
means for receiving digital signals from an optical pick-up unit; means for providing a focus control effort to position the optical pick-up unit; and means for calibrating a focus error signal gain in the means for providing the focus control effort.
RELATED APPLICATIONS
[0001] This application is related to provisional application Serial No. 60/264,351, entitled “Optical Disk Drive Servo System,” by Ron J. Kadlec, Christopher J. Turner, Hans B. Wach, and Charles R. Watt, from which this application claims priority, herein incorporated by reference in its entirety.
Provisional Applications (1)
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Number |
Date |
Country |
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60264351 |
Jan 2001 |
US |