Devices and methods to improve tracking error signals for optic storage systems
A circuit for generating a compensation signal (TC) to compensate a tracking error (TE) swing in a servo control system, the TC signal being pre-defined in accordance with an algorithm for generating a TE signal, the circuit comprising a set of peak detection devices corresponding to a set of photo-detector elements formed in a photo-detector, each of the peak detection devices detecting an amplitude of an optical detection signal derived from a corresponding photo-detector element, a set of amplifiers of a same gain corresponding to the set of peak detection devices, the gain being selectable between an inverting and a non-inverting terminals, a set of gain selection signals corresponding to the set of amplifiers to select one of the inverting and non-inverting terminals in accordance with the pre-defined TC signal, and an adder for adding the amplitudes that are gain selected.
1. A circuit for generating a compensation signal (TC) to compensate a tracking error (TE) swing in a servo control system, the TC signal being pre-defined in accordance with an algorithm for generating a TE signal, the circuit comprising:
a set of peak detection devices corresponding to a set of photo-detector elements formed in a photo-detector, each of the peak detection devices detecting an amplitude of an optical detection signal derived from a corresponding photo-detector element;
a set of amplifiers of a same gain corresponding to the set of peak detection devices, the gain being selectable between an inverting and a non-inverting terminals;
a set of gain selection signals corresponding to the set of amplifiers to select one of the inverting and non-inverting terminals in accordance with the pre-defined TC signal; and
an adder for adding the amplitudes that are gain selected.
2. The circuit of claim 1 , the gain being determined by dividing a peak amplitude of a swing signal representing the TE swing with a peak amplitude of the pre-defined TC signal.
3. The circuit of claim 1 , the amplifiers further comprising:
a set of unitary amplifiers of a gain selectable between 1 and −1, each of the unitary amplifiers being coupled between a corresponding peak detection device and the adder; and
an amplifier of the same gain as each of the set of amplifiers coupled to the adder.
4. The circuit of claim 1 further comprising:
a set of sample-and-hold devices corresponding to the photo-detector elements; and
a sampling pulse to activate the set of sample-and-hold devices at a sample time point.
5. The circuit of claim 1 , the algorithm further comprising differential phase detection, push-pull and 3-beam.
6. The circuit of claim 1 , the pre-defined TC signal further comprising a linear combination of peak (X) that represents an envelope peak amplitude value of an optical detection signal derived from a photo-detector element X of a photo-detector of the servo control system.
7. A servo control system comprising:
a photo-detector to detect a position of a laser spot;
a set of photo-detector elements formed in the photo-detector to provide optical detection signals regarding the position of the laser spot;
an amplifier circuit to generate a tracking error (TE) signal in accordance with an algorithm; and
a circuit for generating a compensation signal (TC) to compensate a swing of the TE signal, the circuit further comprising:
a set of peak detection devices corresponding to the set of photo-detector elements, each of the peak detection devices detecting a peak amplitude of an optical detection signal derived from a corresponding photo-detector element;
a set of amplifiers of a same gain corresponding to the set of peak detection devices, the gain being selectable between an inverting and a non-inverting terminals;
a set of gain selection signals corresponding to the set of amplifiers to select one of the inverting and non-inverting terminals; and
an adder for adding the amplitudes that are gain selected.
8. The system of claim 7 , the TC signal being pre-defined in accordance with the algorithm.
9. The system of claim 8 , the gain being determined by dividing a peak amplitude of a swing signal representing the TE swing with a peak amplitude of the pre-defined TC signal.
10. The system of claim 8 , the pre-defined TC signal further comprising a linear combination of peak (X) representing an envelope peak amplitude value of an optical detection signal derived from a photo-detector element X of a photo-detector of the servo control system.
11. The system of claim 9 , the swing signal representing the TE swing being associated with the algorithm.
12. The system of claim 7 , the algorithm further comprising differential phase detection, push-pull and 3-beam.
13. The system of claim 7 , the amplifiers further comprising:
a set of unitary amplifiers of a gain selectable between 1 and −1, each of the unitary amplifiers being coupled between a corresponding peak detection device and the adder; and
an amplifier of the same gain as each of the set of amplifiers coupled to the adder.
14. The system of claim 7 , the circuit for generating the TC signal further comprising:
a set of sample-and-hold devices corresponding to the photo-detector elements; and
a sampling pulse to activate the set of sample-and-hold devices at a sample time point.
15. The system of claim 7 further comprising a controller including a low-band part and a high-band part.
16. The system of claim 15 , the TC signal being combined with the TE signal in the amplifier circuit.
17. The system of claim 16 , the TC signal and the TE signal combined in the controller being sent to the low-band part.
18. The system of claim 15 , the TC signal being held in the controller for a predetermined time.
19. A servo control system comprising:
a photo-detector to detect a position of a laser spot;
a set of photo-detector elements formed in the photo-detector to provide optical detection signals regarding the position of the laser spot;
a tracking error (TE) signal generated in accordance with an algorithm;
a compensation signal (TC) associated with the algorithm to compensate a TE signal swing further comprising a linear combination of peak (X) representing an envelope peak amplitude value of an optical detection signal derived from one of the photo-detector elements X of the photo-detector; and
a swing signal associated with the algorithm to represent the TE signal swing;
wherein a peak amplitude of the swing signal and a peak amplitude of the TC signal are measured in compensating the TE signal swing.
20. The system of claim 19 , the peak amplitude of the swing signal being divided with the peak amplitude of the TC signal to determine a gain.
21. The system of claim 20 , the TC signal being multiplied by the gain to compensate the TE signal swing.
22. The system of claim 19 , the algorithm further comprising differential phase detection, push-pull and 3-beam.
23. A servo control system comprising:
a first circuit to generate a tracking error (TE) signal in accordance with an algorithm;
a TE swing produced in generating the TE signal in accordance with the algorithm;
a swing signal associated with the algorithm generated to represent the TE swing; and
a second circuit to generate a compensation signal (TC) to compensate the TE swing, the TC signal being K times in amplitude and reverse in polarity with respect to the TE swing, K being a coefficient;
wherein the coefficient K is determined by dividing a peak amplitude of the swing signal with a peak amplitude of the TC signal.
24. A method of compensating a tracking error (TE) swing in a servo control system, comprising:
determining an algorithm for generating a TE signal;
generating a swing signal associated with the algorithm that represents the TE swing;
generating a compensation signal (TC) associated with the algorithm;
measuring an amplitude of the swing signal as V TE ;
measuring an amplitude of the TC signal as V TC ; and
determining a gain by dividing V TE with V TC .
25. The method of claim 24 further comprising:
determining whether V TE is in phase with V TC ;
determining the gain as −V TE /V TC if V TE and V TC are in phase, or as V TE /V TC if V TE and V TC are out of phase;
multiplying the TC signal with the determined gain; and
adding the multiplied TC signal to a circuit for generating the TE signal.
26. The method of claim 24 , the algorithm further comprising differential phase detection, push-pull and 3-beam.
27. The method of claim 24 , the generating of a swing signal further comprising biasing a focus error signal to generate the swing signal.
28. The method of claim 24 , the generating of a swing signal further comprising tilting a disc during rotation to generate the swing signal.
29. The method of claim 24 , the generating of a swing signal further comprising applying a force to a tracking coil to generate the swing signal.
30. The method of claim 24 , the generating of a TC signal further comprising generating the TC signal in a linear combination of peak (X) that represents an envelope peak amplitude value of an optical detection signal derived from a photo-detector element X of a photo-detector of the servo control system.
31. A method of compensating a tracking error (TE) swing in a servo control system, comprising:
providing an algorithm;
providing a first circuit to generate a tracking error (TE) signal in accordance with the algorithm;
generating a swing signal associated with the algorithm to represent a TE swing produced in generating the TE signal;
providing a second circuit to generate a compensation signal (TC) to compensate the TE swing, the TC signal being K times in amplitude with respect to the TE swing, K being a coefficient; and
determining the coefficient K by dividing a peak amplitude of the swing signal with a peak amplitude of the TC signal.
32. The method of claim 31 , the algorithm further comprising differential phase detection, push-pull and 3-beam.
33. The method of claim 31 , the TC signal further comprising a linear combination of peak (X) that represents an envelope peak amplitude value of an optical detection signal derived from a photo-detector element X of a photo-detector of the servo control system.
34. A method of compensating a tracking error (TE) swing in a servo control system, comprising:
providing a photo-detector to detect a position of a laser spot;
providing a set of photo-detector elements formed in the photo-detector to provide optical detection signals regarding the position of the laser spot;
generating a tracking error (TE) signal in accordance with an algorithm;
generating a compensation signal (TC) associated with the algorithm in a linear combination of peak (X) that represents an envelope peak amplitude value of an optical detection signal derived from one of the photo-detector elements X of the photo-detector; and
generating a swing signal associated with the algorithm to represent a TE swing produced in generating the TE signal.
35. The method of claim 34 further comprising:
measuring an amplitude of the swing signal as V TE ;
measuring an amplitude of the TC signal as V TC ; and
determining a gain by dividing V TE with V TC .
36. The method of claim 35 further comprising:
determining whether V TE is in phase with V TC ;
determining the gain as −V TE /V TC if V TE and V TC are in phase, or as V TE /V TC if V TE and V TC are out of phase;
multiplying the TC signal with the determined gain; and
adding the multiplied TC signal to a circuit for generating the TE signal.