Abstract: In a miniature electric motor employing therein pole teeth adapted to be energized by means of a coil accommodated in a bobbin, the improvement in which the pole teeth are fixedly unified with a non-magnetic material into a mass. In an electric motor having such a fixedly unified pole teeth mass structure incorporated therein, the high precision, mutual positional relationship of the constituent parts can be ensured. Moreover, since the pole teeth are formed in a unitary mass, machine workings such as cutting, grinding, and the like can be applied to the unitary mass without restriction, thereby to enable the spacing between the rotor and stator to be small and uniform, leading to increase in efficiency of the electric motor.

Abstract: A synchronous micromotor having a central rotor shaft coaxially surrounded by a permanent magnet structure including a plurality of north poles and a plurality of south poles which circumferentially alternate with the north poles, all of these poles being circumferentially distributed about the rotor shaft and directed outwardly away from the latter. The permanent magnet structure is in turn coaxially surrounded by a cylindrical wall structure which is in turn coaxially surrounded by an annular outer coil structure. The cylindrical wall structure is made of a soft magnetic material and has a pair of annular yoke portions surrounding the rotor shaft and spaced axially one from the other, the cylindrical wall structure having between the annular yoke portions thereof a plurality of elongated apertures each extending from one to the other of the yoke portions helically with respect to the axis of the rotor shaft.

Abstract: A synchronous micrometer wherein the rotor has a permanent magnet structure. This permanent magnet structure is surrounded by a cylindrical stator component of soft magnetic material formed with elongated axially extending cutouts which except for their opposed ends are of substantially elliptical configuration to define between themselves elongated axially extending wall portions of the cylindrical stator component which are of a substantially hourglass configuration. To one end of this cylindrical stator component is fixed a transverse wall which engages a transverse wall of a casing which houses a coil structure which coaxially surrounds the cylindrical stator component as well as the permanent magnet rotor.