Abstract: An optical recording and/or reproducing apparatus comprising a light beam generator, a photodetector, an optical path forming device for causing a light beam from the light beam generator to impinge upon an optical disc and for guiding the light beam emanating from the optical disc to the photodector, and a signal generating circuit block operative to obtain based on a detection output obtained from the photodetector a first signal representing a tracking condition of the light beam in relation to a record track portion on the optical disc and a second signal different in phase by substantially ninety degrees from the first signal and to produce a tracking error signal which satisfies the following equation:St=Sl/{K.(Sl.sup.2 +S2.sup.2).sup.1/2+S2}where St stands for the tracking error signal, Sl stands for the first signal, S2 stands for the second signal and K stands for a constant equal to or more than 1.

Abstract: The separation type optical pick-up device includes a movable optical unit and a stationary optical unit having a detection portion for detecting a discrepancy between an optical axis of a light beam emitted from an emitting portion of the stationary optical unit and an optical axis of a light beam returned from the movable optical unit, and is adapted to correct the discrepancy while driving a carriage of the movable optical unit on the basis of the detected discrepancy.

Abstract: An optical disc drive that employs a velocity feedback loop for detecting the moving velocity of an optical pickup, thereby to enable the optical pickup to seek a target recording track of an optical disc. The number of tracks to the target recording track is calculated on the basis of a signal derived from the optical pickup and a target velocity signal is supplied to the velocity feedback loop in accordance with the calculated result, whereby the moving velocity of the optical pickup can be controlled to become [0] at a timing (time point) at which the optical pickup reaches the target recording track.