Patent ID: 7536135

Claim:
A rotor drive controlling unit, comprising: a motor; a transfer device for transferring a rotational force of the motor; a rotor connected to the transfer device and rotated by the rotational force of the motor; at least three elements-to-be-detected arranged on a periphery centered on a rotation axle of the rotor; a detector for detecting the elements-to-be-detected; a passage time detecting unit for detecting an interval between adjacent elements-to-be-detected passing the detector based on detecting signals generated by the detector; an amplitude/phase generating unit for generating an amplitude and a phase of a rotation period fluctuation of a desired period of the rotor based on the interval detected by the passage time detecting unit; a rotation controlling unit for controlling rotation of the motor based on the amplitude and the phase generated by the amplitude/phase generating unit and for reducing the rotation period fluctuation; and a control reference updating unit for updating the phase, at which updated phase a rotation control of the motor is started, based on the phase generated by the amplitude/phase generating unit with reference to the elements-to-be-detected when widths of the at least three elements-to-be-detected mutually differ.