Track retrieval system for optical disk

A track retrieval system for retrieving a track of an optical disk based on track cross pulses which correspond to a number of tracks scanned by a scan beam, said track retrieval system comprising:

• pulse shaping means for generating a pulse at a zero-crossing of a track error signal which is dependent on a tracking error of the scan beam relative to the track;
• masking means, coupled to said pulse shaping means, for outputting track cross pulses by masking an output of said pulse shaping means for a predetermined time after the pulse is output from said pulse shaping means, so that pulses generated by said pulse shaping means within the predetermined time due to chattering are eliminated, said predetermined time being determined based upon a moving speed of the scan beam, said masking means including means for passing only a first pulse output from said pulse shaping means to said counter means at each zero crossing of the track error signal;
• counter means, coupled to said masking means, for counting the track cross pulses output from said masking means and for outputting a counted value;
• and
• control means, coupled to said counter means, for setting the predetermined time in said masking means based on the moving speed of the scan beam which is calculated from the counted value output from said counter means, said control means also controlling the moving speed of the scan beam.

A track retrieval system for retrieving a track of an optical disk based on track cross pulses which correspond to a number of tracks scanned by a scan beam, said track retrieval system comprising:

• pulse shaping means for generating a pulse at a zero-crossing of a track error signal which is dependent on a tracking error of the scan beam relative to the track;
• correcting means, coupled to said pulse shaping means, for outputting a track cross pulse if said pulse shaping means outputs no pulse within a predetermined time, so that a pulse dropout of the track cross pulse is compensated, said predetermined time being determined based upon a moving speed of the scan beam;
• counter means, coupled to said pulse shaping means and said correcting means, for counting the track cross pulses output from said pulse shaping means and said correcting means and for outputting a counted value;
• and
• control means, coupled to said counter means, for setting the predetermined time in said correcting means based on the moving speed of the scan beam which is calculated from the counted value output from said counter means, said control means also controlling the moving speed of the scan beam.

A track retrieval system for retrieving a track of an optical disk based on track cross pulses which correspond to a number of tracks scanned by a scan beam, said track retrieval system comprising:

• pulse shaping means for generating a pulse at a zero-crossing of a track error signal which is dependent on a tracking error of the scan beam relative to the track;
• masking means, coupled to said pulse shaping means, for outputting track cross pulses by masking an output of said pulse shaping means for a first predetermined time after the pulse is output from said pulse shaping means, so that pulses generated by said pulse shaping means within the first predetermined time due to chattering are eliminated;
• correcting means, coupled to said pulse shaping means, for outputting a track cross pulse if said pulse shaping means outputs no pulse within a second predetermined time, so that a pulse dropout of the track cross pulse is compensated, wherein the first and second predetermined times are determined based upon a moving speed of the scan beam;
• counter means, coupled to said masking means and said correcting means, for counting the track cross pulses output from said masking means and for outputting a counted value;
• and
• control means, coupled to said counter means, for setting the first predetermined time in said masking means and the second predetermined time in said correcting means, based on a moving speed of the scan beam which is calculated from the counted value output from said counter means, said control means also controlling the moving speed of the scan beam.