TLN signal generating apparatus used in optical disc drive and optical disc drive equipped with the apparatus, and optical disc drive equipped with amplitude adjusting apparatus for tracking error signal

摘要

An optical disc drive equipped with a TLN signal generating apparatus is disclosed. The TLN signal generating apparatus includes a TLN signal generating circuit for generating a TLN signal (track loss signal) based on signals obtained from an optical pick-up; a digitizing circuit for digitizing the TLN signal by comparing it with a reference level; and a correction circuit for correcting the TLN signal so that it is accurately digitized by the digitizing circuit irrespective of an offset component which is a direct current component contained in the TLN signal. The correction circuit is comprised of an offset component detecting circuit for detecting a level of the offset component contained in the TLN signal; and a signal control circuit for controlling, responsive to the level of the offset component detected by the offset component detecting circuit, a level of the TLN signal generated by the TLN signal generating circuit so that the level of the TLN signal will become a level which does not receive any influence from the level of the direct component. The correction circuit can also be comprised of a signal correcting circuit which amplifies an alternating current component contained in the TLN signal without eliminating a directed current component contained in the TLN signal.