Patent ID: 8422347

Claim:
A method for determining a phase difference of a tracking error signal in an optical disc drive, wherein the tracking error signal is formed by the optical disc drive to maintain beam spots focused at an optical disc and to move along data tracks, the method comprising: predetermined a plurality of phase differences for the tracking error signal; measuring a main push-pull (MPP) signal and a secondary push-pull (SPP) signal of the predetermined phase differences, respectively, wherein the main push-pull (MPP) signal is formed by a main optical transducer of the optical disc drive and the secondary push-pull (SPP) signal is formed by two secondary transducers of the optical disc drive; calculating an amplitude ratio (MPP+SPP)/(MPP−SPP); establishing an amplitude ratio table for the predetermined phase differences and the corresponding amplitude ratios (MPP+SPP)/(MPP−SPP); and measuring MPP and SPP signals for a tracking error signal under test for phase difference, and calculating the amplitude ratio (MPP+SPP)/(MPP−SPP) to determine the phase difference of the tracking error signal under test according to the established phase difference amplitude ratio table.