Optimizing focus point for optical disc
View Patent ↗An apparatus comprising a focus controller, a photo-diode sensor, a data circuit, a focus error creation circuit and a focus offset circuit. The focus controller may be configured to control a lens in relation to a laser beam and allow the laser beam to focus on a disc. The photo-diode sensor may be configured to generate one or more photo-diode signals in response to the laser beam. The data circuit may be configured to generate one or more disc status signals in response to the one or more photo-diode signals. The focus error creation circuit may generate a focus error signal. The focus error signal may provide a first value based on a focus point of the laser beam. The focus offset circuit may be configured to offset the first value of the focus error signal to a second value in response to the disc status signals to allow the focus controller to move the lens to a position which will increase the focus point of the laser beam on the disc.
1. An apparatus comprising:
a focus controller configured to control a lens in relation to a laser beam and allow said laser beam to focus on a disc;
a photo-diode sensor configured to generate one or more photo-diode signals in response to said laser beam;
a data circuit configured to generate disc status signals in response to said one or more photo-diode signals;
a focus error creation circuit to generate a focus error signal, wherein said focus error signal provides a first value based on a focus point of said laser beam; and
a focus offset circuit configured to offset said first value of said focus error signal to a second value to allow said focus controller to move said lens to a position which will increase the focus point of said laser beam on said disc, wherein (i) said disc status signals comprise one or more of a data signal and a beam push-pull signal, (ii) in a first mode, the focus offset signal is generated in response to said data signal, and (iii) in a second mode the focus offset signal is generated in response to said beam push-pull signal.
2. The apparatus according to claim 1 , wherein said focus offset circuit is configured to offset said first value of said focus error signal to said second value to increase the quality of a reading process when reading data from said disc.
3. The apparatus according to claim 1 , wherein said focus offset circuit is configured to offset said first value of said focus error signal to said second value to increase the quality of a writing process when writing data to said disc.
4. The apparatus according to claim 1 , wherein said data circuit comprises a data signal creation circuit configured to generate said data signal when reading data from said disc.
5. The apparatus according to claim 1 , wherein said data signal comprises a radio frequency signal.
6. The apparatus according to claim 1 , wherein said data circuit comprises a beam push-pull creation circuit configured to generate said beam push-pull signal when writing data to said disc.
7. The apparatus according to claim 1 , wherein said beam push-pull signal is a low frequency signal.
8. The apparatus according to claim 1 , wherein said apparatus operates in said first mode when reading data from said disc and operates in said second mode when writing or rewriting data to said disc.
9. An apparatus comprising:
means for controlling a lens in relation to a laser beam to allow said laser beam to focus on a disc;
means for generating one or more photo-diode signals in response to said laser beam;
means for generating disc status signals in response to said one or more photo-diode signals;
means for generating a focus error signal which provides a first value based on a focus point of said laser beam; and
means for offsetting said first value of said focus error signal to a second value to move said lens to a position which will increase the focus point of said laser beam on said disc, wherein (i) said disc status signals comprise one or more of a data signal and a beam push-pull signal, (ii) in a first mode, the focus offset signal is generated in response to said data signal, and (iii) in a second mode the focus offset signal is generated in response to said beam push-pull signal.
10. A method for increasing the focus point of a laser beam on an optical disc, comprising the steps of:
(A) controlling a lens in relation to said laser beam to allow said laser beam to focus on said disc;
(B) generating one or more photo-diode signals in response to said laser beam;
(C) generating disc status signals in response to said one or more photo-diode signals;
(D) generating a focus error signal which provides a first value based on a focus point of said laser beam; and
(E) offsetting said first value of said focus error signal with a focus offset signal to a second value to move said lens to a position which will increase the focus point of said laser beam on said disc, wherein (i) said disc status signals comprise one or more of a data signal and a beam push-pull signal, (ii) in a first mode, the focus offset signal is generated in response to said data signal, and (iii) in a second mode the focus offset signal is generated in response to said beam push-pull signal.
11. The method according to claim 10 , wherein step (E) further comprises the step of:
offsetting said first value of said focus error signal to said second value to increase the quality of a reading process when reading data from said disc.
12. The method according to claim 11 , wherein step (A) further comprises the step of:
controlling a lens in relation to said laser beam to allow said laser beam to focus on said disc while at the same time controlling said laser beam to lock on a physical track on said disc.
13. The method according to claim 12 , wherein step (E) further comprises the steps of:
(F) applying a predetermined amount of constant offset to said focus error signal with said focus offset signal;
(G) measuring a peak-to-peak value of one of said data signal in response to applying said predetermined amount of constant offset; and
(H) adjusting said focus offset signal by a fixed predetermined amount.
14. The method of claim 13 , further comprising the steps of:
repeating steps (F), (G) and (H) a number of times to collect a number of (i) peak-to-peak values of one of said data signal and (ii) adjusted values of said focus offset signal.
15. The method according to claim 14 , further comprising the steps of:
finding a second-order curve using (i) said number of peak-to-peak values of one of said data signal and (ii) said adjusted values of the focus offset signal; and finding said second value from said second order curve.
16. The method according to claim 10 , wherein step (E) further comprises the step of:
offsetting said first value of said focus error signal to said second value to increase the quality of a writing process when writing data to said disc.
17. The method according to claim 16 , wherein step (A) further comprises the step of:
controlling a lens in relation to said laser beam to allow said laser beam to focus on said disc without controlling said laser beam to lock on a physical track on said disc.
18. The method according to claim 17 , wherein step (E) further comprises the steps of:
(J) applying a predetermined amount of constant offset to said focus error signal with said focus offset signal;
(K) measuring a peak-to-peak value of said beam push-pull signal in revolutions in response to applying said predetermined amount of constant offset; and
(L) adjusting said focus offset signal by a fixed predetermined amount.
19. The method of claim 18 , further comprising the steps of:
repeating steps (J), (K) and (L) a number of times to collect a number of (i) peak-to-peak values of said beam push-pull signal and (ii) adjusted values of said focus offset signal.
20. The method according to claim 19 , further comprising the steps of:
finding a second-order curve using (i) said number of peak-to-peak values of said beam push-pull signal and (ii) said adjusted values of the focus offset signal; and
finding said second value from said second order curve.