Drive connection mechanism, and image forming apparatus having the drive connection mechanism

An image forming apparatus comprising:

• a image holding unit;
• a drive unit for rotating the image holding unit;
• an image forming means for forming an image in the periphery of the image holding unit rotated by the drive unit;
• a transfer means for transferring the image formed on the periphery of the image holding unit by the image forming means to a transfer medium;
• and
• a drive connection mechanism which coaxially connects the drive shaft to transfer the driving force of the drive unit to the image holding unit,
• wherein the drive connection mechanism has:
• splines which are extended in an axial direction along the periphery of the drive shaft and formed parallel to each other with equal intervals;
• a convex coupling gear which is provided with internal gears to engage with the splines, arranged rotatably together with the drive shaft through the internal gears and slidably in the axial direction of the drive shaft, provided with a first tapered surface inclined in the axial direction to converge toward the image holding unit on an outer circumference remote from the drive shaft, the first tapered surface having a first bevel gear, and divided into several parts in the circumferential direction;
• an energizing member which energizes the convex coupling gear divided into several parts in the axial direction toward the image holding unit;
• and
• a concave coupling gear which is provided in the image holding unit, and has a concave part having a second tapered surface opposite to the first tapered surface of each of the convex coupling gear divided into several parts, and a second bevel gear to engage with the first bevel gear on the second tapered surface;
• and
• the first bevel gear of the convex coupling gear is stuck without a clearance to the second bevel gear of the concave coupling gear, the drive shaft is connected to the image holding unit, and the splines of the drive shaft are stuck without a clearance to the internal gears of the convex coupling gear, and the centers of the drive shaft and image holding unit are automatically aligned, in the state that the convex coupling gear is pressed to the concave coupling gear by the energizing force of the energizing member, and the drive shaft is connected to the image holding unit.