Patent ID: 7764578

Claim:
An optical disc reproduction method, comprising the steps of: irradiating reproduction light onto an optical disc on which information is recorded by using a plurality of marks with different mark lengths; receiving reflected light from the optical disc by a quadrant photo detector; generating a pulse signal by using a first readout signal and a second readout signal each of which is a sum signal of outputs from segment elements located respectively at diagonal corners of the quadrant photo detector, the pulse signal including information on the phase difference between the first readout signal and the second readout signal, and having at least one of a height and a width weighted according to a mark length of a mark so that the area of the pulse signal would be larger as the mark length of a mark adjacent to an edge of the readout signal becomes longer; generating a tracking error signal by adding up the pulse signals for a certain period of time; and controlling tracking by using the tracking error signal.