Abstract: Disclosed is the improvement in a dynamic air pressure bearing in which a rotor is supported at high speed in the non-contact state. In an optical deflector, a stationary shaft is planted at the center portion of a housing. A stator core is disposed on a stud. A magnet yoke is integrated with a sleeve rotated relative to the stationary shaft. The magnet yoke contains an inner magnet and an outer magnet. A rotary polygonal mirror is mounted on a flange fixed on the sleeve by means of a center screw and a mirror cap. The rotary polygonal mirror is rotated at high speed together with the sleeve relative to the stationary shaft, thus constituting a dynamic air pressure bearing between the shaft and the sleeve. The stationary shaft is constituted of a main body and a ring-like bearing member fitted in the main body. The bearing member is formed of a ceramic material and formed with grooves for generating dynamic air pressure. The sleeve is preferably constituted of a main body and a bearing member of ceramic.

Abstract: An electric motor, in which the thrust bearing action is performed by the magnetic attraction forces induced between a annular stator core with toroidal coils and magnets confronting the stator core, includes at least a cup-shaped member with a central cylindrical portion opened at the center, the cup-shaped member serving as a magnet yoke and a seat on which an element to be driven by the motor is mounted, and a cylindrical rotary sleeve press-fitted in the central cylindrical portion. This construction contributes to a reduction of the weight, size and manufacturing cost of the motor.

Abstract: An electric motor includes at least a stator core carrying toroidal coils wound thereon, a magnet provided in opposition to the stator core so as to constitute a part of a rotor, and magnetic flux detection elements for detecting changes in magnetic polarity of the magnet so as to control a current flowing in the toroidal coils. The stator is provided with a select number of cut portions at its open end. The number of cut portions is not less than that of the magnetic flux detection elements. The winding positions of the toroidal coils are considered in order to maintain magnetic symmetry, the magnetic flux detection elements being provided in the cut portions.