Patent ID: 6680590
Filing Date: 2004-01-20
Classification: H02P

Abstract:
A vibration motor comprising:(a) a rotor having an unbalanced load; (b) a stator having a plurality of coils having different phases respectively; (c) a motor driver coupled with the coils and rotating said rotor, said motor driver including; (c-1) a starting-circuit for applying starting torque to said vibration motor; (c-2) a back-electromotive-force(BEMF)-detecting circuit for detecting BEMF of each phase of said vibration motor and outputing a BEMF detecting signal corresponding to the BEMF; (c-3) an output-driving circuit having; a timing-generating circuit for producing at least one signal to switch an ON-OFF state sequentially for the coils based on the BEMF detecting signal, (c-4) a speed-controlling circuit having a reference-cycle-generating circuit for generating a reference cycle signal and a cycle-comparing circuit for comparing a cycle of the reference cycle signal with a cycle of the BEMF detecting signal so that an ON-OFF period to power said coils is effected responsive to output from said speed controlling circuit.