Staas & Halsey
Multi-phase hybrid stepper motor
 To minimize fluctuation of torque, improve torque stiffness, and reduce resonance vibration during rotation in the hybrid stepper motor. The magnetic poles have two or more teeth placed with the same spaces as with toothpitch of the rotor. The total number (NS) of the teeth of the nonsymmetrical stators is determined by NS=5.times.(n0 +nl), where n0 is the number of teeth of each of five poles and nl is the number of teeth of each of remaining five poles. The nonsymmetrical stator, of which the teeth are nl, is placed between the nonsymmetrical stators, of which the teeth are n0, so that the nonsymmetrical stator, of which the teeth are n0, is placed on the opposite side of the nonsymmetrical stator, of which the teeth are n1, when the core of the rotation axis is the center. The total number (NS) of the teeth (NR) of the rotor and the teeth of the stators corresponds to the relationship of NS.gtoreq.0.8 NR (NS is equal to or greater than 0.8 NR), and the difference between NR and NS is defined by the equation NR-NS=K(S0-S1)+10(S1-1+B), where K is an integer between 2 and 5, S0 and S1 are integers as small as possible in such a way that S1 can also be equal to S0, B is a fraction of 1, 10B is an integer. The ten windings produce as many north-and south-poles as necessary by using a power supply method to supply applied power to achieve full step angles =electrical angle 90.degree.=.alpha.F, .alpha.F=360.degree./10 NR and half step angle=electrical angle 45.degree.=.alpha.H, .alpha.H =360.degree./20NR. 
Minebea Co., Ltd.
H
H02K
inventional
Kenji Noriyuki
Yoshida Yoshimura