US Patent 7616538 Method for setting layer-jump point on optical disc

A method for setting a layer-jump point on a multilayer optical disc in an optical drive for accessing the multilayer optical disc. First, a magnetic-pole cycle value is accumulated. Next, a lag control signal of the optical drive is detected to record the magnetic-pole cycle value as a magnetic-pole basic value. Then, a magnetic-pole offset value is generated according to a phase difference between the lag control signal and an oscillating position of the multilayer optical disc. Finally, a layer-jump-point reference value, according to which the optical drive moves from one layer of the multilayer optical disc to another layer thereof to access data, is set by adding the magnetic-pole basic value to the magnetic-pole offset value.