US 7,023,767 B2 · Gain calibration device and method for differential push-pull tracking error signals

Abstract

A gain calibration device and method for differential push-pull (DPP) tracking error signals in an optical storage system is provided. The gain calibration method processes the synthesized gain (SPPG) of the sub beam in the DPP tracking error signal components with respect to the main beam. The calibration theorem resides in controlling the objective lens of the pick-up head to form a lens-shift or controlling the tilt of the objective lens relative to the optical disc to make the synthesized DPP tracking error signals generate a correspondingly signal variation owing to the optical path deviation. The synthesized gain is calibrated to make the signal variation a minimum value, and the calibrated synthesized gain is the optimum value. In the method and device of the invention, the optimum synthesized gain of the sub beam is precisely computed without the assumptions of equal intensity of the two sub beams and symmetrical positions of the two sub beams with respect to the main beam, and without knowing the ratio of the pitch between the two sub beams to the track pitch.

Claims16

Dependent claims

A gain calibration method for DPP (differential push-pull) tracking error signals in an optical storage system for correcting a ratio of an amplifier gain of a sub beam to an amplifier gain of a main beam, the gain calibration method comprising the steps of:

powering on a laser light source and focusing laser beams;
enabling a spindle motor;
controlling a first state of an objective lens relative to a disc;
measuring an eigenvalue of the push-pull signal of the main beam, with respect to an objective lens-shift, as a first main beam eigenvalue;
measuring an eigenvalue of the push-pull signal of the sub beam, with respect to the objective lens-shift, as a first sub beam eigenvalue;
controlling a second state of the objective lens relative to the disc;
measuring an eigenvalue of the push-pull signal of the main beam, with respect to an objective lens-shift, as a second main beam eigenvalue;
measuring an eigenvalue of the push-pull signal of the sub beam, with respect to the objective lens-shift, as a second sub beam eigenvalue;
and
computing the gain ratio of the sub beam to the main beam according to the first main beam eigenvalue, first sub beam eigenvalue, second main beam eigenvalue, and second sub beam eigenvalue.

7 more elements

A gain calibration device for DPP (differential push-pull) tracking error signals in an optical storage system for correcting a ratio of an amplifier gain of a sub beam to an amplifier gain of a main beam, the gain calibration device comprising:

an optical signal amplifier for receiving signals of the main beam and the sub beam from a disc, amplifying the signals, and outputting them as a main beam radio frequency signal and a sub beam radio frequency signal;
a radio frequency receiver for differentially amplifying, in a front-stage, the main beam radio frequency signal and the sub beam radio frequency signal of the optical signal amplifier, for differentially amplifying the amplified signals by a main beam signal amplifier and a sub beam signal amplifier, for generating a main beam push-pull signal and a sub beam push-pull signal, and for outputting the value of (sub beam push-pull signal—main beam push-pull signal) as the DPP tracking error signal;
an analog to digital converter for receiving the main beam push-pull signal and the sub beam push-pull signal from the radio frequency receiver, and generating a digital main beam push-pull signal and a digital sub beam push-pull signal;
and
a digital signal processor for receiving the digital main beam push-pull signal and the digital sub beam push-pull signal, extracting eigenvalues of the digital main beam push-pull signal and the digital sub beam push-pull signal using a feature extractor, and computing, using a gain computing module, a gain ratio of the sub beam signal amplifier of the radio frequency receiver to the main beam signal amplifier according to the eigenvalues of the push-pull signal.

2 more elements

Dependencies are inferred from the claim text.

Gain calibration device and method for differential push-pull tracking error signals

Life of this patent

Gain calibration device and method for differential push-pull tracking error signals

Life of this patent

Abstract

Claims16