Patent ID: 8229327

Claim:
An image forming apparatus, comprising: an image bearing body having a surface for carrying thereon a toner image; a driving motor configured to drive the image bearing body according to a control signal; and a controller configured to output the control signal to the driving motor so as to cause the driving motor to output a motor output velocity having a period equal to that of an AC velocity component of the image bearing body to reduce the AC velocity component of the image bearing body fluctuating periodically, wherein the control signal comprises a discrete motor input signal to the driving motor, the discrete motor input signal being generated by sampling a continuous motor input signal at a sampling period, the continuous motor input signal corresponds to a sinusoidal wave approximation of a rotating velocity of the image bearing body having the AC velocity component, and the sinusoidal wave approximation has a phase angle that has been adjusted to minimize an amplitude of the AC velocity component, wherein the phase angle is about 270°, and wherein the controller is further configured to increase the phase angle as the sampling period becomes longer.