Tracking controller for recording track of narrow track pitch

A tracking controller in a recorded information reproducing apparatus having information reading means for reading recorded information from a recording disk based on a read signal produced by opto-electrically transducing reflected light when a reading beam is irradiated to said recording disk, tracking error detecting means for detecting a tracking error based on said read signal, and a tracking actuator for forcing said information reading beam to follow a recording track on said recording disk based on said tracking error, wherein a position read by said information reading means on a central recording track within three recording tracks adjacent to each other is referenced, said tracking controller comprising:

• error detecting means for calculating an error value between a read signal read from said central recording track and a predetermined value;
• a coefficient calculating means for calculating a first coefficient from a correlation between a read signal read from a radial position substantially identical to said read position on a first adjacent recording track adjacent to said central recording track on the inner peripheral side of the disk and said error value, and for calculating a second coefficient from a correlation between a read signal read from a radial position substantially identical to said read position on a second adjacent recording track adjacent to said central recording track on the outer peripheral side of the disk and said error value;
• and
• means for calculating a difference value between said first coefficient and said second coefficient as a tracking offset, and subtracting said tracking offset from said tracking error to correct the tracking offset.

A tracking controlling method of a recorded information reproducing apparatus comprising:

• detecting a tracking error based on reflected light from a recording information disk when a reading beam is irradiated to the disk;
• calculating an error value between a read signal read from a recording track intended for reading and predetermined value;
• calculating a first coefficient from a correlation between said error value and a first signal read from a first recording track adjacent to said recording track intended for reading and on the inner peripheral side of the disk;
• calculating a second coefficient from a correlation between said error value and a second signal read from a second recording track adjacent to said recording track intended for reading and on the outer peripheral side of the disk;
• calculating a difference value between said first coefficient and said second coefficient as a tracking offset;
• subtracting said tracking offset from said detected tracking error to obtain a corrected tracking error signal;
• and
• forcing the reading beam to follow a recording track on the disk based on said corrected tracking error signal.