Abstract: A motor with reduced radial forces includes a first motor part made up of 2P permanent magnet poles surrounding a second motor part formed by a magnetic yoke having a number T of pole teeth and with an air gap between the first and second motor parts. The first and second motor parts are moveable relative to one another. Exciter coils are mounted on the pole teeth and the pole teeth are separated by pole gaps. For a motor with a number 2P magnet poles and a number T of pole teeth which do not have a common submultiple greater than 1, each of the pole teeth have a centrally located auxiliary slot facing the air gap thereby to reduce undesirable radial forces.

Abstract: A magnetic drive arrangement comprising a plurality of magnetically cooperating parts which are moveable relative to one another, one of the parts being connected to a drive shaft and one of the parts being stationary, the fields produced by the permanent magnets being modulated by soft-magnetic flux-carrying parts which include at least one toothed iron yoke, wherein structures are provided on both sides of the iron yoke to generate magnetic fields by means of permanent magnets at the sides facing the iron yoke, with the magnetic fields alternatively exhibiting north poles and south poles along the circumference.

Abstract: The invention relates to an electric motor with permanent-magnet excitation, particularly inside-rotor and outside-rotor motors, comprising motor sections (10, 20) which are movable relative to one another, of which the first motor section (10) forms a multi-pole excitation field in an air gap (1) by means of permanent magnets (11) and of which the second motor section (20) is a soft-iron yoke (21) having pole teeth (22) which project towards the air gap (1) and which carry excitation coils (23).

Abstract: In an electrodynamic actuator for an optical write-in or read-out unit (11), which is aligned with respect to signal tracks of a storage medium in order to direct a focused light beam (13) onto a work position, the actuator includes an optical unit (11) is arranged on a movable permanent magnet arrangement (5, 5a) which can be moved by means of stationary coils (17a, 17b, 19a, 19b) located in its vicinity in focusing (z) and radial (x) directions running perpendicular to one another, the coils being located in the radial direction (x) on both sides of the permanent magnet arrangement (5, 5a), and the magnetization of the permanent magnet arrangement being chosen in such a way that its magnetic field in the region of coils (17c, 17d, 19c, 19d) opposite to it has both an x component and z component, the permanent magnet arrangement (5, 5a) with the optical unit (11) in the magnetic field of the coils is arranged at the free ends of spring rods (3) clamped at one end, and the spring rods (3) of the permanent mag

Abstract: A positioning device for positioning an element, such as an optical element used to direct a radiation beam with respect to tracks on a carrier, with respect to translation along three mutually perpendicular axes and pivoting about two of those axes. Two sets of coils are disposed one at each end of a permanent magnet structure, each set having at least three coils having axes generally parallel to the structure axis, and arranged to co-act with the external return field of the magnet structure such that selective electrically energizing of two or more of the coils will produce a reaction force in the structure for positioning the structure in one or more of the selected degrees of freedom.