Abstract: In an electric motor with a stationary and a movable active motor part, one of the two active motor parts comprising a motor winding and the other a motor magnet, an air gap being formed between said active motor parts. The motor winding (9) is built up on a synthetic resin carrier foil and is formed through local removal of copper material with which the synthetic resin foil (23) had previously been fully coated. The synthetic resin carrier foil (23) and the planar coils (28) adhering thereto are provided with an adhesive filler material (30) such that the adhesive filler material (30) fills up the gaps (26) formed between the individual conductor tracks through the removal of the copper material. The assembly thus stabilized is wound into an evenly rounded cylinder.

Abstract: An improved spindle motor, particularly for a hard-disc drive, having a stator in the form of a cylindrical coil carried by a mounting plate and a permanent magnet rotor carried on a rotatable hub. At its outer circumference the rotor generates a field perpendicular to the axis of rotation. A bell-shaped portion of the hub surrounds the coil. The hub is supported on the motor shaft by axial and radial hydrodynamic bearings. A soft-iron sleeve-shaped yoke externally surrounds the coil configuration. This permits the coil to be free of soft-magnetic parts, thereby reducing its inductance and improving the dynamic drive characteristics of the motor. The coil is preferably formed by curved foil windings, so there are no winding slots. This avoids the production of detent torques.

Abstract: Armature (4) is driven by piezo-electric vibration elements (1) which are made to resonate by means of high-frequency electrical oscillations in order to produce ultrasonic vibrations which are transmitted to a plurality of drive pins (2) arranged as brushes a friction surface (6) of the armature (4) is pressed against free ends (5) a of the pins, the individual drive pins bein disposed at an angle .alpha. relative to the perpendicular to the contact portion of the friction surface (6). The angle of inclination .alpha. is then substantially equal to the static-friction angle or is slightly larger than this static-friction angle between the drive pins and the friction surface. Suitably, the angle of inclination is selected to be between 10.degree. and 30.degree..