A permanent magnet device includes a permanent magnet having north and south pole faces with a first pole piece positioned adjacent one pole face thereof and a second pole piece positioned adjacent the other pole face thereof so as to create at least two potential magnetic flux paths. A first control...http://www.google.com.au/patents/US6342746?utm_source=gb-gplus-sharePatent US6342746 - Methods for controlling the path of magnetic flux from a permanent magnet and devices incorporating the same
