Optical medium reproduction apparatus and method of reproducing optical medium

An optical medium reproduction apparatus for optically reproducing an optical medium where a plurality of tracks are formed, comprising:

• a detection unit for splitting asymmetrically a cross section of a beam returned from the optical medium into a plurality of regions in a tangential direction and for forming respective detection signals of a plurality of the regions;
• a multiple input adaptive equalizer having a plurality of adaptive equalizer units, wherein the respective detection signals of a plurality of the regions are inputted into the plurality of adaptive equalizer units, and the outputs of the plurality of adaptive equalizer units are computed to from equalization signals;
• a binarization unit for binarizing the equalization signals to provide binary data;
• and
• an equalization error computing unit for determining an equalization error from equalization target signals provided based on the binary data from the binarization unit and the equalization signals outputted from the multiple input adaptive equalizer, and providing the adaptive equalizer units with the equalization error as control signals for adaptive equalization,
• a plurality of the regions formed by splitting being four or more.