Patent ID: 7207102

Claim:
A method for forming a plurality of permanent magnets with two different north-south magnetic pole alignments, comprising the steps of: (a) magnetizing each permanent magnet with the same north-south magnetic pole alignment; and (b) switching the north-south magnetic pole alignment of a portion of the permanent magnets by: (i) temporarily heating the portion of the permanent magnets to a temperature in a range of 0–200° C. below a Curie temperature of the portion of the permanent magnets, thereby reducing a first threshold for switching of the north-south magnetic pole alignment of the portion of the permanent magnets; and (ii) exposing the portion of the permanent magnets to a magnetic field which is directed oppositely to the north-south magnetic pole alignment of the permanent magnets, with the oppositely-directed magnetic field having a magnetic field strength which is above the first threshold for switching the alignment of the portion of the permanent magnets, while being below a second threshold for switching of the north-south magnetic pole alignment for a remainder of the permanent magnets.