Bistable electromagnetic latch

Claim 1

An electromagnetic latch comprising a magnetic circuit including a pair of magnetic pole pieces, each pole piece having an arcuate portion and a further portion, a permanent magnet rotor supported for rotation about an axis centered between said arcuate portions with said arcuate portions embracing said rotor, said arcuate portions each having first ends not merging into said further portions and spaced to define the respective ends of a first magnetic gap and each having second ends merging into said further portions, respectively, and defining respective ends of a second magnetic gap, said gaps subtending substantially equal angles about said axis, said magnetic rotor having opposite magnetic poles associated with said magnetic gaps, respectively, each magnetic pole being rotatable between the ends of the associated magnetic gap, whereby alternate magnetic paths of low reluctance and corresponding stable positions of the rotor are defined when each magnetic pole of the rotor is adjacent to either end of the associated magnetic gap, and coil means connected to said further portions of said pole pieces and responsive to the momentary flow of electrical current therethrough for producing a magnetic flux in the magnetic circuit that causes the rotor to move from one stable position to the other.