Patent ID: 6963521

Claim:
A disc drive apparatus for recording and reproducing data to and from an optical disc-like storage medium which has tracks formed thereon each constituting a wobble with a frequency and which includes land and groove fields for storing said data in retrievable fashion, said disc drive apparatus comprising: wobble signal generating means for generating a wobble signal representative of information about said wobble detected based on reflected light from said optical disc-like storage medium under a light beam emitted to a disc signal surface of the storage medium; land/groove detecting means for determining by using the wobble signal, when said light beam fails to trace a specific track correctly on said storage medium, whether the emitted light beam is located on a land field or in a groove field, said land/groove detecting means further outputting a land/groove detection signal having a waveform inverted depending on whether said light beam is located on said land field or in said groove field; moving direction determining means for determining a radial moving direction of said light beam over said disc signal surface based on a phase difference between said land/groove detection signal and a tracking error signal that represents how much said light beam deviates from said specific track on said disc signal surface; and controlling means for executing control so as to prevent said light beam from moving in the direction determined by said moving direction determining means.