Tracking and focus servo system with head load
View Patent ↗A head load algorithm for an optical disk drive is presented. On startup, the optical media can be spun up. Then an optical pick-up unit can be positioned at an extreme position, for example at the inner diameter, and focus can be closed. The optical pick-up unit then can be incrementally moved away from the extreme position while the tracking error signal is monitored to locate an area of the optical media with tracks. Once the area is located, a tracking servo system can close on one of the tracks.
1. A method of starting an optical disk drive, comprising:
spinning an optical media in the optical disk drive;
providing a tracking control signal that positions an optical pick-up unit at an extreme position;
closing a focus servo system at the extreme position;
adjusting the tracking control signal to move the optical pick-up unit away from the extreme position until a tracking error signal appropriate for an area on the optical media with tracks is located; and
closing a tracking servo system on a track of the optical media.
2. The method of claim 1 , wherein providing the tracking control signal includes setting the tracking control signal to a predetermined value.
3. The method of claim 1 , wherein the extreme position is at an inner-diameter stop of the optical disk drive, the inner-diameter stop positions the optical pick-up unit over the inner diameter of the optical media.
4. The method of claim 1 , wherein the extreme position corresponds to the outer diameter of the optical disk drive.
5. The method of claim 1 , wherein closing the focus servo system includes
supplying a focus control signal profile that moves the optical pick-up unit to a first position;
providing a focus control signal that moves the optical pick-up unit from the first position towards a focus position while monitoring a sum signal;
calculating the focus control signal from a focus error signal when the sum signal exceeds a focus sum threshold.
6. The method of claim 1 , wherein adjusting the tracking control signal includes incrementing the tracking control signal by an incremental value.
7. The method of claim 6 , wherein the tracking error signal appropriate for the area of optical media with tracks is located by
sampling the tracking error signal;
calculating the mean of the tracking error signal;
setting a limit range based on the mean;
counting the number of samples of the tracking error signal during a particular rotation of the optical media that are within the limit range to form a count; and
indicating that the area of optical media with tracks is located if the count is above a threshold value.
8. The method of claim 7 , wherein the particular rotation is one revolution of the optical media.
9. The method of claim 1 , further including
determining the media type of the area of optical media with tracks; and
setting operating parameters for the optical disk drive appropriate for that media type.
10. The method of claim 1 , wherein the optical media at the extreme position includes a bar code area.
11. 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 control signals; and
a driver coupled to control positions of the optical pick-up unit in response to the control signals,
wherein the at least one processor executes an algorithm that
spins an optical media in the optical disk drive,
provides a tracking control signal, which is one of the control signals, that positions the optical pick-up unit at an extreme position,
closes the focus servo system at the extreme position,
adjusts the tracking control signal to move the optical pick-up unit away from the extreme position until a tracking error signal appropriate for an area on the optical media with tracks is located, and
closes a tracking servo system on a track of the optical media.
12. The drive of claim 11 , wherein the tracking control signal is set to a predetermined value to move the optical pick-up unit to the extreme position.
13. The drive of claim 11 , wherein the extreme position is at an inner-diameter stop of the optical disk drive, the inner-diameter stop positions the optical pick-up unit over the inner diameter of the optical media.
14. The drive of claim 11 , wherein the extreme position corresponds to the outer diameter of the optical disk drive.
15. The drive of claim 11 , wherein the tracking control signal is adjusted by incrementing the tracking control signal by an incremental value.
16. The drive of claim 15 , wherein the tracking error signal appropriate for the area of optical media with tracks is located by
sampling the tracking error signal;
calculating the mean of the tracking error signal;
setting a limit range based on the mean;
counting the number of samples of the tracking error signal during a particular rotation of the optical media that are within the limit range to form a count; and
indicating that the area of optical media with tracks is located if the count is above a threshold value.
17. The drive of claim 16 , wherein the particular rotation is one revolution of the optical media.
18. The drive of claim 11 , wherein the algorithm directs the at least one processor further to
determine the media type of the area of optical media with tracks; and
set operating parameters for the optical disk drive appropriate for that media type.
19. An optical disk drive, comprising:
means for moving an optical pick-up unit to an extreme position over an optical media;
means for closing a focus servo system at the extreme position;
means for finding an area of the optical medium with tracks; and
means for closing a tracking servo system on a track in the area.