Patent ID: 8463162

Claim:
An image forming apparatus comprising: a driver unit utilizing a motor as a driving source and operable to rotate a load shaft connected with at least one of a sheet conveyance roller and a rotative image carrier; and a controller operable to control the driver unit to regulate a rotation speed of the load shaft, wherein the driver unit includes a variable speed transmission unit for transmitting a driving force and changing a transmission ratio between the motor and the load shaft, the variable speed transmission unit includes: a pair of pulleys each having a groove in a circumferential surface thereof and each divided into a pair of pulley segments in the middle of an axis thereof; a V-shaped belt suspended between the grooves of the pair of pulleys; and a distance changer unit changing, for each pair of pulley segments, a distance between the pair of pulley segments, to change the transmission ratio, and the controller is configured to perform: a first control for controlling, after the motor starts to rotate targeting a target rotation speed, the variable speed transmission unit to cause the distance changer unit to change the transmission ratio to a predetermined ratio; and a second control for detecting the rotation speed of the load shaft after completion of the first control, and changing the rotation speed of the motor by feedback control, to change the rotation speed of the load shaft to a target rotation speed.