Patent ID: 6819068
Filing Date: 2004-11-16
Classification: H02K

Abstract:
A brushless dc motor comprising:a stator having a plurality of poles and a driver member; a first Hall sensor electrically connected to the driver member; a second Hall sensor electrically connected to the driver member; and a rotor axially combined with the stator and comprising a driver permanent magnet and a frequency permanent magnet, said driver permanent magnet and frequency permanent magnet each having a plurality of alternating opposite poles; wherein when the rotor is rotated about an axis of the stator, the first Hall sensor detects a first alternation of the poles of the driver permanent magnet to thereby alternatively actuate the poles of the stator, and wherein the second Hall sensor detects a second alternation of the poles of the frequency permanent magnet to detect changes in a frequency of said second alternation, said detected changes in the frequency of said second alternation being output to a computer system, for use by the computer system as a reference.