A rotary drive apparatus including a frame having at least three holes; a yoke having a center portion and two side bar portions on opposite sides of the center portion, the center portion having a hole, coils mounted on the side bar portions of the yoke, a collar having a bore and being tightly mounted on the surface of the hole of the yoke, magnetic parameter changing elements being mounted on the surface of the bore of the collar, and a rotor having magnetic poles in the radial direction and being inserted into the bore of the collar with a predetermined clearance. In the apparatus, a first hole of the frame is parallel to a first direction of the apparatus and has a cross-section for tightly receiving the center portion of the yoke, and a second and third holes of the frame are in a second direction perpendicularly intersecting the first direction and being concentric with each other oppositely the first hole, the center portion of the yoke being fit into the first hole. The position of the collar is adjusted through the second hole during the adjustment, and the third hole passes a shaft connected to one end of the rotor.
An electromagnetic position control apparatus including a rotary sphere having a permanent magnet. The rotary sphere is rotably supported within a spherical hole formed at a crossing portion of a cross-shaped yoke. Coils are used to create magnetic fields at the rotary sphere. The position of rotation of the rotary sphere is controlled in three dimensions by means of changing the intensity of the direct current supplied to the coils or the duty cycle of the pulse current supplied to the coils to change the intensity of the magnetic fields.
In a preferred embodiment, an oscillating stepping motor having only one stator phase. What would otherwise be a second stator phase is a magnet fixedly disposed with respect to the rotor to produce a detent position of the rotor. When the stator is energized, the field of the fixed magnet is at least partially overcome and the rotor steps to a first predetermined position. When the stator is de-energized, the rotor returns to the detent position. Alternately energizing and de-energizing the stator causes the rotor to oscillate between the two positions. Alternatively, an angle of oscillation twice that produced above may be provided by reversing the stator field to oscillate the rotor between the first predetermined position and a second predetermined position produced by reversing the stator field.
