Polarized electromagnetic actuator device

Claim 1

A polarized electromagnetic actuator device comprising: an armature pivotally supported for movement about a pivot axis between two different angularly displaced positions; an electromagnet having a core, an exciter coil wound only around the core, and a pair of pole members extending from the ends of the core toward the ends of the armature on either side of the pivot axis; a bar-shaped three-pole magnetized permanent magnet disposed between the free ends of the sole members to extend along the armature in a closely adjacent relationship thereto, said permanent magnet being magnetized to have end poles of the same polarity at its lengthwise ends and to have a center pole of the opposite polarity to the end poles intermediate its ends so as to produce opposing first and second flux paths between the permanent magnet and the armature; said first flux path circulating between the center pole and the one of the end poles through one end portion of the permanent magnet and the adjacent end portion of the armature, and said second flux path circulating between the center pole and the other end pole through the other end portion of the permanent magnet and the adjacent end portion of the armature; said first and second flux paths extending through a common air gap between the permanent magnet and the armature in proximity to the pivot axis; and said center pole being offset from the pivot axis of the armature along the length of the permanent magnet so that said common air gap is correspondingly offset therefrom to thereby produce a torque on the armature tending to rotate the armature about the pivot axis toward the one of the angularly displaced positions.