Patent ID: 6124710
Filing Date: 2000-09-26
Classification: G01D,H02K

Abstract:
An apparatus comprising:a) a housing suitable sized to be coupled to a motor housing, said housing having a hole therein;b) a coupling means extending from within the housing, through the hole, for coupling the apparatus to a motor shaft;c) a first disc-shaped pole piece attached to an interior surface of said housing such that a hole in said first disc-shaped pole piece aligns with said hole in said housing;d) a disc-shaped magnet attached to said coupling means within said housing, a face of said disc shaped magnet having alternating polarity;e) a second disc-shaped pole piece attached to said coupling means and located between said coupling means and said disc-shaped magnet, said first and second disc-shaped pole pieces providing a magnetic path; andf) a Hall effect device attached to said housing, said Hall effect device positioned between said first disc-shaped pole piece and said disc-shaped magnet, said Hall effect device sensing said alternating polarity on the face of said disc-shaped magnet as said coupling means rotates.