Method and related apparatus for deriving a tracking error signal

• US 7,345,963 B2
• Filed: 08/22/2006
• Issued: 03/18/2008
• Est. Priority Date: 04/07/2003
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Cheng, Yuh
• Primary Examiner(s): Young; Wayne
• Assistant Examiner(s): HOFFNER, LINH NGUYEN
• Application Number:
  US11/466,109
• Publication Number:
  US 20060291345A1
• Time in Patent Office: 574 Days
• Field of Search: 369/44.25, 369/44.27
• US Class Current: 369/44.25
• CPC Class Codes: G11B 7/0906 Differential phase difference systems
• CPC Class Codes: G11B 7/0943 Methods and circuits for performing mathematical operations on individual detector segment outputs

Abstract

A method for deriving a tracking error signal based on a first analog detection signal and a second analog detection signal. The method includes summing the first analog detection signal and the second analog detection signal to generate an analog sum signal. An analog delay device is utilized to delay the analog sum signal to be a delay signal. The delay signal is digitalized into a digital delay signal. The first analog detection signal and the second analog detection signal are respectively transformed into a first digital detection signal and a second digital detect signal. The tracking error signal is then generated utilizing a comparing operation among the digital delay signal, the first digital detect signal, and the first digital detect signal.

Claims

1. A method for deriving a tracking error signal in an optical storage system comprising:

(a) receiving an optical beam reflected and refracted via a recording carrier, the optical beam propagating along a track direction on the recording carrier according to the tracking error signal;

(b) after proceeding with step(a), according to a plurality of received different portions of the optical beam in space, generating a first analog detection signal and a second analog detection signal, wherein there is a time difference between the first analog detection signal and the second analog detection signal;

(c) after proceeding with step(b), respectively transforming the first analog detection signal and the second analog detection signal into a first digital detection signal and a second digital detect signal;

(d) after proceeding with step(b), summing the first analog detection signal and the second analog detection signal to generate an analog sum signal;

(e) after proceeding with step(d), applying a delay operation to the analog sum signal to be a delay signal;

(f) after proceeding with step(e), digitalizing the delay signal into a digital delay signal; and

(g) after proceeding with step(e) and step(f), respectively comparing the digital delay signal with the first digital detection signal and comparing the digital delay signal with the second digital detection signal to generate the tracking error signal.

2. The method of claim 1 wherein the optical storage system comprises an optical sensor, and the optical sensor comprises a plurality of detecting sections, which respectively correspond to the plurality of portions of the optical beam in space for generating a plurality of corresponding output signals according to the plurality of portions of the optical beam.

3. The method of claim 2 wherein the optical storage system further comprises a detection signal generating module, which is electrically connected to the optical sensor for providing a combination process for the plurality of output signals to generate the first analog detection signal and the second analog detection signal, so that the time difference between the first analog detection signal and the second analog detection signal represents a deviation between a central spot of the optical beam on the recording carrier and the track direction.

4. The method of claim 1 wherein the optical storage system comprises an equalizer for executing the delay operation in step(e).

5. The method of claim 1 wherein the optical storage system comprises a relay for executing the delay operation in step(e).

6. The method of claim 1 wherein the optical storage system comprises an equalizer and a relay, and the equalizer and the relay are electrically connected to each other for executing the delay operation in step(e).

7. The method of claim 1 wherein the optical storage system comprises a first comparator, a second comparator, and a filtering device, the method further comprising:

(h) in step(g), utilizing the first comparator to process the digital delay signal and the first digital detection signal to generate a first comparing signal, utilizing the second comparator to process the digital delay signal and the second digital detection signal to generate a second comparing signal; and

(i) in step(g) and after proceeding with step(h), subtracting the first comparing signal from the second comparing signal to generate a time-difference signal, and utilizing the filtering device to process the time-difference signal to generate the tracking error signal.

8. The method of claim 7 wherein the first comparator and the second comparator are respectively an XOR (Exclusive OR) logic gate.

9. The method of claim 1 further comprising:

(j) in step(b), according to the plurality of received portions of the optical beam, generating a third analog detection signal and a fourth analog detection signal;

(k) after proceeding with steps(j), summing the first analog detection signal, the second analog detection signal, the third analog detection signal, and the fourth analog detection signal into an analog summing signal, and applying the delay operation to the analog summing signal to generate a delay summing signal;

(l) after proceeding with step(k), digitalizing the delay summing signal into a digital delay summing signal;

(m) after proceeding with steps(j), respectively transforming the third analog detection signal and the fourth analog detection signal into a third digital detection signal and a fourth digital detect signal; and

(n) after proceeding with step(l) and step(m), applying a plurality of comparing processes to the digital delay summing signal respectively with the first digital detect signal, the second digital detect signal, the third digital detect signal, and the fourth digital detection signal to generate the tracking error signal.