Shaft coupling, and function unit drive device for an image forming device comprising the same

A device for driving a function unit of an image forming device, comprising:

• a motor;
• a drive shaft connected to the motor;
• a driven shaft connected to the function unit and coaxially arranged with the drive shaft;
• and
• a shaft coupling that connects the drive shaft with the driven shaft;
• the shaft coupling comprising:
• a first coupling attached to one of the drive shaft and the driven shaft;
• a second coupling attached to the other of the drive shaft and the driven shaft, the second coupling capable of moving toward and away from the first coupling;
• and
• an urging member that urges at least one of the first coupling and the second coupling toward the other;
• wherein the first coupling includes a first coupling portion having a first end face which is formed on a side opposite the second coupling and which extends in the axial direction, and a first concave portion which is formed on a side surface opposite the second coupling;
• the second coupling includes a second coupling portion having a second end face which extends in the axial direction and is capable of surface-to-surface contact with the first end face of the first coupling portion and a first convex portion which extends toward the first coupling and configured to be inserted into the first concave portion;
• and
• the first concave portion of the first coupling portion further includes a cam face with which at least a tip of the first convex portion is capable of coming into contact with in order to convert a pressing force of the first convex portion into a pressing force between the first end face and the second end face.