Abstract: A magnetic levitation actuator includes a pair of U-shaped first permanent magnets provided on opposite sides of an object to be driven with a pair of outwardly projecting first legs defining the U-shape. A pair of guide rails are spaced apart from the object on opposite sides thereof, and a pair of U-shaped second permanent magnets are provided on associated guide rails and extend along the guide rails. Each of the second permanent magnets is provided with a second pair of legs defining the U-shape of the associated second magnets and opposed to the associated first legs of the first magnets with a predetermined gap therebetween. The first legs and second legs, which are opposed to each other, have opposite polarities to produce a magnetic attraction therebetween.

Abstract: An optical disk apparatus comprises an optical pickup having an optical pickup body carrying a laser and a photodetector responsive to light emitted from the laser and reflected by the optical disk for producing tracking error signals mounted on the optical pickup body for reciprocal movement in a tracking direction responsive to operation of an actuator, and supports an objective for focusing the beam on the disk. A position sensor produces position signals in response to displacement of the movable portion in the tracking direction. Finally a servo tracking circuit outputs driving signals to the actuator on the basis of tracking error signals produced either in response to tracking error signals produced from outputs of the photodetector and position signals produced from output signals of the position sensor, in response only to the latter.