| 摘要 |
<p>A time base error correction system for use in an apparatus for recovering a signal from a track recorded on a disc, wherein the signal includes a periodic synchronizing signal that defines a time base, and the apparatus includes optical system for directing a source beam of radiation to follow along the track and a spindle servo device for rotating the disc relative to the source beam, to produce a modulated beam of radiation containing the signal, the optical system device further directing the modulated beam to a signal recovery device for recovering the signal from the modulated beam, the time base error correcting system comprising: a separator for separating the synchronizing signal from the signal recovered from the modulated beam; a reference signal generator for generating a reference signal having a prescribed frequency; a phase detector for detecting the relative phase between the synchronizing signal and the reference signal; and for generating a control signal representative of error in relative phase; a radial location detector for detecting the radial location of the source beam relative to the disc; a control signal adjustor for adjusting the control signal as a function of the radial location of the source beam relative to the disc; and tangential beam steerer responsive to the control signal for steering the source beam tangentially along the information track to vary the rate of relative movement between the source beam and the disc in a manner correcting for time base errors in the signal recovered from the modulated beam.</p> |
