Patent ID: 8095045

Claim:
A rotary developing unit comprising: a rotary body that rotates around a rotation axis; a first developing device arranged on a circumferential surface of the rotary body, comprising: a first toner storage chamber that houses toner supplied from a first toner entry port; and a first developer holder that develops an electrostatic latent image formed on an image holder with toner supplied from the first toner storage chamber; a second developing device arranged on a circumferential surface of the rotary body, comprising: a second toner storage chamber that houses toner supplied from a second toner entry port; and a second developer holder that develops an electrostatic latent image formed on an image holder with toner supplied from the second toner storage chamber; a toner supply container that is inserted between the first developing device and the second developing device in an insertion direction substantially parallel to that of the rotation axis to be attached to the first developing device, and that supplies toner to the first toner storage chamber of the first developing device through a supply port of the toner supply container and the first toner entry port of the toner storage chamber; a first guide formed on the toner supply container; a second guide formed on the second developing device, that is configured to slide along the first guide when the toner supply container is inserted between the first developing device and the second developing device, and to be detached from the first guide before the toner supply container is attached to the first developing device; a first position fixing unit provided at the first developing device; and a second position fixing unit provided at the toner supply container, that is configured to fix a position of the toner supply container in a direction substantially perpendicular to the insertion direction, in cooperation with the first position fixing unit of the first developing device, before the second guide of the second developing device is detached from the first guide.