Patent ID: 7035175

Claim:
An offset measuring method for measuring an offset superimposed on a tracking error signal based on an optical beam reflected by an information medium, in a recording and reproduction apparatus including an optical pickup placed on transportation means so as to be driven along a radial direction of the information medium, the method comprising: a first offset amount measuring step of directing an optical beam toward a first measuring position on the information medium from the optical pickup, thereby measuring a first offset amount based on the optical beam reflected at the first measuring position; a transportation means moving step of, after the first offset amount measuring step, moving the transportation means having the optical pickup placed thereon by a first distance in a first direction along the radial direction; a first optical pickup driving step of driving the optical pickup on the transportation means by a second distance, which is substantially equal to the first distance, in a second direction which is opposite to the first direction; and a second offset amount measuring step of, after the transportation means moving step and the first optical pickup driving step, directing an optical beam toward a second measuring position on the information medium from the optical pickup, thereby measuring a second offset amount based on the optical beam reflected at the second measuring position.