Abstract: A disk drive according to a first embodiment includes a pickup movable along a radial direction of the disk and a reversing mechanism for moving the pickup from one side of the disk to the other side by rotating the pickup about an axis corresponding to the radial direction of the disk. In a second embodiment, there can be only one pickup which can reverse sides of the disk or a pickup on each side of the disk. The pickup(s) are moved along guide rails on either side of the disk and the guide rails are supported by rotatable base members. A linking arm links the two base members together so that rotation of one will cause rotation of the other. In a third embodiment, a pickup and a rack are supported on a slider for moving the pickup along the surface of a disk. The rack has three toothed surfaces including first, second, and third surfaces for engaging first, second and third feed screws, respectively.

Abstract: An information reading and reproducing apparatus in which a recording disc having an information-carrying face formed with recorded tracks is to be driven for rotation and which includes drive means operative to drive a signal pick-up means for movement radially of the disc at a velocity controlled by a velocity control device and to produce signals indicative of the locations of the pick-up spot relative to the tracks on the disc in a radial direction of the disc, the velocity control device comprising velocity detecting means operative to extract from said signals information indicative of the velocity of movement of the signal pick-up means with respect to the disc.