Granted Patent B2

US 7,911,892 · App. 12/506,469 · Granted Mar 22, 2011

Assignee: LSI Corporation

Abstract

Claims (41)

1. An apparatus comprising:

a center error creation circuit configured to generate a center error signal in response to light from a main laser reflected from a surface of an optical disc;

a center error offset injection circuit configured to (i) determine a value of said center error signal when a lens in a sled housing is at a mechanical center and (ii) generate an offset signal based upon said value, wherein said center error offset injection circuit measures an average value of said center error signal over a predetermined amount of time when a lens suspension which holds said lens in place is in a mechanical equilibrium state.

2. The apparatus according to claim 1 , wherein said center error offset injection circuit is configured to determine an amount of offset needed to keep said lens at said mechanical center during a tracking open-loop calibration operation.

3. The apparatus according to claim 1 , further comprising:

a center error controller configured to adjust said lens in said sled housing at said mechanical center in response to said offset signal when said apparatus is in a rough seek mode.

4. The apparatus according to claim 1 , wherein said lens suspension comprises one or more springs.

5. The apparatus according to claim 1 , further comprising one or more photo-diode sensors configured to generate one or more photo-diode signals in response to the reflected light from said surface of said optical disc, wherein said center error signal is generated in response to said one or more photo diode signals.

6. The apparatus according to claim 1 , wherein said apparatus further comprises:

a sled controller configured to move said sled housing over a predetermined number of tracks during a rough seek mode.

7. The apparatus according to claim 1 , further comprising:

a track controller configured to lock a laser with said lens onto one or more tracks with a tracking error signal when said apparatus is in one of a track follow mode and a fine seek mode.

8. The apparatus according to claim 7 , wherein said lens is positioned at said mechanical center when said track controller locks said laser with said lens on said tracks.

9. An apparatus comprising:

means for generating a center error signal in response to light from a main laser reflected from a surface of an optical disc;

means for (i) determining a value of said center error signal when a lens in a sled housing is at a mechanical center and (ii) generating an offset signal based upon said value, wherein said determining and generating means measures an average value of said center error signal over a predetermined amount of time when a means for holding said lens in place is in a mechanical equilibrium state.

10. The apparatus according to claim 9 , further comprising:

means for adjusting said lens in said sled housing at said mechanical center in response to said offset signal when said apparatus is in a rough seek mode.

11. A method for adjusting a lens in a sled housing of an optical disc system, comprising the steps of:

(A) generating a center error signal in response to light from a main laser reflected from a surface of an optical disc;

(B) determining a value of said center error signal when said lens in said sled housing is at a mechanical center by measuring an average value of said center error signal over a predetermined amount of time when a lens suspension which holds said lens in place is in a mechanical equilibrium state;

(C) generating an offset signal based upon said value; and

(D) adjusting said lens in said sled housing at said mechanical center in response to said offset signal when in a rough seek mode.

12. The method according to claim 11 , further comprising the steps of:

determining whether said sled housing has completed stepping to a target sled position; and

outputting a step motor control signal when said sled housing has not completed stepping to said target sled position.

13. The method according to claim 12 , further comprising the steps of:

determining whether one or more tracks of said optical disc and said lens have slowed down relative to each other; and

activating a track controller when said tracks and said lens have slowed down relative to each other.

14. The method according to claim 13 , further comprising the steps of:

determining whether said main laser is locked to said one or more tracks of said optical disc; and

completing said rough seek mode when said main laser is locked to said one or more tracks.

15. The method according to claim 14 , further comprising the step of:

determining whether said one or more tracks and said lens have slowed down relative to each other when said laser beam is not locked to said one or more tracks of said optical disc.

16. The method according to claim 11 , further comprising switching control of said lens from a center error controller to a track controller when said sled housing reaches a target sled position.

17. The method according to claim 11 , wherein said main laser is unlocked from said optical disc during said rough seek mode.

18. The method according to claim 11 , further comprising the step of switching control of said lens from the center error signal to a tracking error signal at an end of the rough seek mode.

19. The method according to claim 11 , further comprising the steps of:

generating one or more photo-diode signals in response to the light from said main laser reflected from said surface of said optical disc; and

generating said center error signal in response to said one or more photo-diode signals.

20. The method according to claim 11 , wherein said lens suspension comprises one or more springs.

Assignments (8)

Continuity (2)