PLAYBACK METHOD AND APPARATUS

摘要

PURPOSE: A playback method and apparatus are provided to reproduce information in an optimal state in heterodyne detection by producing a secondary harmonic wave carrier signal. CONSTITUTION: A playback method comprises steps of producing a push-pull signal from reflected light of an optical disk(S601); producing a wobble clock and a calibration gate signal, on the basis of the push-pull signal(S602); producing a signal having frequency corresponding to secondary higher harmonic, on the basis of the input wobble clock, giving a predetermined phase to the produced signal, and outputting a secondary higher harmonic carrier(S603); abstracting a secondary higher harmonic component(S604); accumulating and adding the accumulated value of a phase error every edge and outputting a phase error-accumulated value(S605); continuously the accumulating and adding process until calibration gate becomes a low level(S606); calculating and outputting the average value of the phase error(S607); renewing the phase of a secondary higher harmonic carrier on the basis of the average value(S608); integrating the multiplied result of the secondary higher harmonic carrier and the secondary higher harmonic component and outputting the multiplied result as a heterodyne detection signal(S609); outputting zero if a held heterodyne detection signal is right and outputting 1 if the held heterodyne detection signal is wrong(S610).