Optical pickup position control method

• US 6,845,067 B2
• Filed: 10/22/2001
• Issued: 01/18/2005
• Est. Priority Date: 10/23/2000
• Status: Expired due to Term

• Current Assignee: Dropbox, Inc.
• Original Assignee: Sony Computer Entertainment Incorporated (Sony Group Corp.)
• Inventors: Ohtsu, Hiroshi
• Primary Examiner(s): Nguyen, Hoa T.
• Assistant Examiner(s): Battaglia, Michael V.
• Application Number:
  US10/011,375
• Publication Number:
  US 20020054549A1
• Time in Patent Office: 1,184 Days
• Field of Search: 369/44.32, 369/53.34, 369/53.18
• US Class Current: 369/44.32
• 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 7/094 Methods and circuits for servo offset compensation
• CPC Class Codes: G11B 7/0945 Methods for initialising servos, start-up sequences
• CPC Class Codes: G11B 7/0946 specially adapted for operation during external perturbations not related to the carrier or servo beam, e.g. vibration
• CPC Class Codes: G11B 7/0948 specially adapted for detection and avoidance or compensation of imperfections on the carrier, e.g. dust, scratches, dropouts G11B7/095 takes precedence
• CPC Class Codes: G11B 7/0956 to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc

Abstract

A position control method, which positions the relative position of an optical disk and an optical pickup to a position that provides the optimum value of the jitter value of the detection signal obtained by detecting the reflected light of an optical spot, has a jitter value acquisition procedure, which carries out multiple feed operations within the adjustment range of the relative position and obtains the jitter value at each feed position, an edge position setting procedure which sets as the edge positions relative positions that exceed a prescribed preset jitter threshold value, an optimum position computation procedure, which computes the optimum position that yields the optimum value for the jitter value, and an edge position setting procedure that sets the edge positions on the condition that there are at least two relative positions that yield a jitter value that exceeds the jitter threshold value.

Claims

1. An optical pickup position control method that is used in an optical disk device that records and/or plays back information by shining an optical spot from an optical pickup onto an optical disk, and that positions the relative position of the optical disk and the optical pickup in a position that gives the optimum value of a jitter value of a detection signal obtained by detecting the reflected light of the optical spot, the method comprising:

(a) a jitter value acquisition procedure that performs multiple feed operations within the adjustment range of the relative position and obtains the jitter value at each feed position,

(b) an edge position setting procedure that, based on the feed positions and jitter values obtained by the jitter value acquisition procedure, sets as the edge positions relative positions that will be greater than a preset prescribed jitter threshold value,

(c) an optimum position computation procedure that computes the optimum position that will give the optimum value of the jitter value, based on the edge positions set by this edge position setting procedure,

(d) an optimum position adjustment procedure that adjusts the relative position of the optical disk and the optical pickup to the optimum position computed by this optimum position computation procedure,

(e) wherein the edge position procedure sets the edge positions on the condition that there are at least two relative positions that will give a jitter value that exceeds the jitter threshold value, and,

(f) wherein the acquisition of the jitter value at each feed position in the jitter value acquisition procedure is achieved by rotating the optical disk at a prescribed speed, taking in multiple jitter values along the inside circumference of the optical disk, and taking the average of the obtained multiple jitter values excluding the maximum value.

3. A method as described in claim 1 or 2, further comprising an implementation decision procedure that decides, according to the type of the optical disk, whether to carry out the jitter value acquisition procedure, the edge position setting procedure, the optimum position computation procedure, and the optimum position adjustment procedure.

4. A method as described in claim 1 or 2, wherein the relative position is the tilt position between the optical disk and the optical pickup.

5. A method as described in claim 1 or 2, wherein the relative position is the focus position between the optical disk and the optical pickup.

6. A method as described in claim 1, further comprising an implementation decision procedure that decides, according to the type of the optical disk, whether to carry out the jitter value acquisition procedure, the edge position setting procedure, the optimum position computation procedure, and the optimum position adjustment procedure.

7. A method as described in claim 1, wherein the relative position is the tilt position between the optical disk and the optical pickup.

8. A method as described in claim 1, wherein the relative position is the focus position between the optical disk and the optical pickup.

9. A method as described claim 1, wherein the relative position is the tilt position between the optical disk and the optical pickup.

10. A method as described in claim 1, wherein the relative position is the focus position between the optical disk and the optical pickup.

2. An optical pickup position control method that is used in an optical disk device that records and/or plays back information by shining an optical spot from an optical pickup onto an optical disk, and that positions the relative position of the optical disk and the optical pickup in a position that gives the optimum value of a jitter value of a detection signal obtained by detecting the reflected light of the optical spot, the method comprising:

(a) a jitter value acquisition procedure that performs multiple feed operations within the adjustment range of the relative position and obtains the jitter value at each feed position,

(b) an edge position setting procedure that, based on the feed positions and jitter values obtained by the jitter value acquisition procedure, sets as the edge positions relative positions that will be greater than a preset prescribed jitter threshold value,

(c) an optimum position computation procedure that computes the optimum position that will give the optimum value of the jitter value, based on the edge positions set by this edge position setting procedure,

(d) an optimum position adjustment procedure that adjusts the relative position of the optical disk and the optical pickup to the optimum position computed by this optimum position computation procedure,

(e) wherein the edge position setting procedure sets the edge positions on the condition that there are at least two relative positions that will give a jitter value that exceeds the jitter threshold value, and

(f) further comprising a jitter characteristics smoothing procedure that, following the jitter value acquisition procedure, smoothes the obtained jitter characteristics if the jitter characteristics by which the jitter values corresponding to the feed positions are plotted are judged not to conform to preset jitter characteristics, and the edge position setting procedure and the optimum position computation procedure are carried out based on the jitter characteristics smoothed by this jitter characteristics smoothing procedure.

11. A method as described in claim 2, wherein the jitter characteristics smoothing procedure is carried out so that, denoting the jitter values obtained at feed position X0≦

X≦

Xmax by J(X0)≦

J(X)≦

J(Xmax), the smoothed jitter values Js(X0), Js(X), J(Xmax) at each feed position are given by;

Js(X0)=[3×

J(X0)+J(X0+1)]/4;

Js(X)=[J(X−

1)+2×

J(X)+J(X+1)]/4;

Js(Xmax)=[J(Xmax−

1)+3×

J(Xmax)]/4;

said edge position setting procedure has

a first edge position setting step that takes as the first edge position the feed position of jitter value Jedge, which is the smaller of Js(X0) and Js(Xmax), and

a second edge position setting step that compares the ledge and each Js(X) in sequence from this first edge position in the direction toward the feed position at which another Js(X0) or Js(Xmax) is taken, and takes as the second edge position the feed position at which Jedge≦

Js(X), and

said optimum position computation procedure calculates the midpoint of the first edge position and the second edge position and takes this midpoint as the optimum position.

12. A method as described claim 11, further comprising an implementation decision procedure that decides, according to the type of the optical disk, whether to carry out the jitter value acquisition procedure, the edge position setting procedure, the optimum position computation procedure, and the optimum position adjustment procedure.

13. A method as described in claim 11, wherein the relative position is the tilt position between the optical disk and the optical pickup.

14. A method as described in claim 11, wherein the relative position is the focus position between the optical disk and the optical pickup.

15. A method as described claim 2, further comprising an implementation decision procedure that decides, according to the type of the optical disk, whether to carry out the jitter value acquisition procedure, the edge position setting procedure, the optimum position computation procedure, and the optimum position adjustment procedure.

16. A method as described claim 2, wherein the relative position is the tilt position between the optical disk and the optical pickup.

17. A method as described claim 2, wherein the relative position is the focus position between the optical disk and the optical pickup.