Bi-directional linear drive motor
 The present invention comprises an improvement of a known bi-directional linear motor and is applicable to other linear motors. The linear motor comprises a plurality of pole pieces arranged as a closed frame having three horizontal pole pieces and two vertical end pieces with permanent magnets mounted therein to form a closed stator core having a symmetrical permanent magnetic flux field path in the stator. A force coil is mounted over the center pole piece of the three horizontal pole pieces. When force current is applied to the force coil a reaction flux is generated in the stator core which creates an unbalanced flux field in the stator core. At least one air gap is provided in at least one of the pole pieces through which the reaction flux passes to increase the magnetic inductance which in turn increase the force on the force coil for a given force current. 
Kulicke and Soffa Industries, Inc.
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H02K H02K
inventional additional
Wei
Zhao