Disc drive unit

摘要

Tilt adjustment for a guide member with respect to a rotational reference surface of a rotary table is made on the basis of an external reference in which an inner peripheral side end of a disc is vertically adjusted by setting an outer peripheral side end as a reference. A given vertical fluctuation amount range of the outer periphery of the disc in rotation and a necessary tilt adjustment amount range for the adjustment of the tilt of an optical axis associated with a head are made to overlap each other. The uppermost end position of the head is situated within the given fluctuation amount of the outer periphery of the disc-shaped recording medium below the rotational reference surface of the disc rotary table.