Image forming apparatus

An image forming apparatus, comprising:

• a plurality of developing units;
• a cam shaft;
• a plurality of cams provided on the cam shaft to correspond to the plurality of developing units and to sequentially operate the plurality of developing units as the cam shaft rotates;
• a regulation means that controls a rotational force from a driving force source that is transferred to the cam shaft and that includes a spring clutch having a plurality of latch portions of which phases correspond to the plurality of cams and an actuator that is selectively connected to the plurality of latch portions and corresponds the plurality of cams to the plurality of developing units, the spring clutch including
• a clutch gear that receives a driving force from the driving force source;
• a clutch shaft connected to the cam shaft;
• a clutch spring connected to the clutch gear and the clutch shaft and transfers the rotational force of the clutch gear to the clutch shaft;
• and
• a clutch hub that covers the clutch spring, one end of the clutch spring being fixed to the clutch hub, and the plurality of latch portions being disposed on the clutch hub;
• and
• a control unit disposed at the spring clutch to substantially prevent the cam shaft from excessive rotation to prevent the cams from being separated from a corresponding position with respect to the selected developing unit, wherein the control unit comprises at least one control member disposed on the spring clutch, and at least one control notch correspondingly formed on the spring clutch to receive the at least one control member.