Patent ID: 7180839

Claim:
A servo controller in an optical recording and/or reproducing apparatus having a pickup unit for tracking an optical recording medium having groove tracks and land tracks, the servo controller comprising: a photo detector to output as two channels a light signal reflected from the optical recording medium in which wobbles of the groove tracks or the land tracks which are a first type of tracks are out of phase with the wobbles of the next other type of tracks and the wobbles of the other type of tracks are in phase with the wobbles of the next first type of tracks, or the wobbles of the groove tracks and the land tracks are out of phase with the wobbles of the next other types of tracks; a wobble signal detector to detect a wobble signal from at least one of the two channels; a wobble signal determiner to determine whether one of the tracks, which is currently tracked by the pickup unit, is a groove track or a land track, and to provide a determination signal; and a controller to generate a control signal for controlling a servo for moving the pickup unit using the determination signal and the detected wobble signal, wherein: the photodetector divides the light signal into two signals; and if the wobbles of the groove tracks have a phase difference of π with the wobbles of the next land tracks, the wobbles of the land tracks are in phase with the next groove tracks, the wobbles formed on one of the groove tracks have a phase difference of π with the wobbles of a very next groove track in a radial direction of the recording medium, and if the wobbles formed on one of the land tracks have a phase difference of π with the wobbles of a very next land track in the radial direction, the wobble signal detector detects a groove wobble signal from a first one of the two channels corresponding to a difference between the two signals output from the photo detector and the wobble signal detector detects a land wobble signal from a second one of the two channels corresponding to a sum of the two signals output from the photo detector.