Patent ID: 7174087
Filing Date: 2007-02-06
Classification: G11B,H03H

Abstract:
1. A playback apparatus for extracting a playback signal from a recording medium without performing tracking control, said playback apparatus comprising: an adaptive equalizing circuit for performing equalization of said playback signal; detection means for determining an envelope value of said playback signal, wherein said adaptive equalizing circuit is controlled in accordance with an envelope value from said detection means; and phase-locked loop means responsive to said playback signal to control said adaptive equalizing circuit when a phase of a clock generated by the phase-locked loop means is locked to the playback signal, wherein said phase-locked loop means generates a detection signal indicating whether the phase of said clock is locked to the playback signal, wherein said phase-locked loop means extracts a data clock from said playback signal only when the envelope value of said playback signal is greater than or equal to a predetermined value, and wherein a characteristic of said adaptive equalizing circuit is changed only when said detection signal indicates that the phase of said clock is locked to the playback signal and the envelope value of said playback signal is greater than or equal to said predetermined value.