Importance

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Abstract

A two phase unipolar brushless direct current motor with asymmetrically arranged pole positions including a rotor portion (12) mounted upon a shaft subassembly (14) and rotating therewith with respect to a stator portion (16). The rotor portion (12) includes a field magnet (22) which is divided into alternately polarized zones (26) and (28) which are of dissimilar sizes, and a commutator magnet (38) to provide for electrical timing. The stator portion (16) includes salient pole positions (44) which are asymmetrically arranged around the circumference of the stator core. A latching hall effect sensor (82) is also provided to act as a commutator triggering element. The motor (10) is characterized in that the asymmetrical arrangement of its magnetic elements prevents there being a zero torque or a detent position. The primary usage of the motor (10) is in digital data storage devices.

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First Claim