Positioning mechanism for developing unit in image forming apparatus

摘要

An image forming apparatus for developing an electrostatic latent image formed on an image carrier, which is rotatable around an central shaft thereof, with plural colors of toner comprises a developing unit assembly an outer peripheral portion of which retains a plurality of developing units each of which includes a developing roller being to be contacted with the image carrier to supply the associated color of the toner thereon, the developing unit assembly rotatable around a central shaft thereof, a first drive member for rotatively driving the developing roller positioned at a contact position of the developing roller and the image carrier, a second drive member for rotatively driving the developing unit assembly to subsequently position each of the developing roller at the contact position so a rotational direction of the developing unit assembly as to be opposed to a rotational direction of the developing unit assembly according to a reaction force derived from the driving of the first drive member.