Abstract: A head positioning apparatus for a disc unit which moves a carriage having a movable portion by driving motors constituted by coils and magnets, wherein driving power distribution of the driving motors is variable, so that the acting points of the driving forces of the driving motors can be variably set at any position to position the acting points of driving forces of the driving motors on a centroidal axis of the movable portion.

Abstract: A carriage assembly has a carriage provided on both sides with voice coils, a magnet assembly surrounding the voice coils and adapted for causing the carriage to move in the radial direction of a disk, and guide rails for guiding the carriage in the radial direction of the disk. The carriage is provided on a lower portion thereof with first rollers for engagement with the guide rails and at its upper portion thereof with second rollers which co-operate with a biasing members in preventing the carriage from moving upward. Either the guide rails or the first rollers are provided with grooves which prevent the first rollers from moving in the tangential directions of the guide rails. Since the movement of the first rollers in the tangential directions of the guide rail is prevented, it is possible to locate the carriage with a high degree of precision with respect to the disk.

Abstract: A two-dimensional image pick-up device using a one-dimensional image pick-up element which is useful as an image reader. Drive coil type linear motors for driving an element moving carriage in the subscanning direction of the one-dimensional image pick-up element are disposed on both sides of the element moving carriage, enabling the deivce to be economically small-sized as a whole.

Abstract: An electromagnetic drive actuator including a magnetic circuit comprising at least one yoke having plate-shaped, L-shaped, E-shaped cross section or the like, at least one magnet mounted on the yoke and a magnetic flux extending from the magnet to the yoke, at least one coil arranged so as to cross the magnetic flux and produce a drive force in a direction crossing a plane including the magnetic path of the magnetic circuit when current is applied to the coil, and at least one magnetic shield member provided at the side portion of the coil to thereby prevent a counter drive force from being produced in a direction opposite to a desired direction of a drive force produced by the coil.