Developing device for mixing and supplying developer

摘要

A developing device having a developing sleeve opposed to a photoreceptor, and a developer transport portion adjacent to the sleeve. The developer transport portion is divided into first and second portions by a partition, and the developer is circulated between the first and second portions. A fresh toner is supplied to the developer in the second portion to be transported to the first portion while being mixed, and thereafter is supplied to the sleeve along an axial direction of the sleeve in the first portion. The second portion is provided with a transport member by which the developer is transported at an upstream side of the second portion with respect to the developer transport direction in the second portion with a speed faster than the toner supply speed and the transport speed of the developer at a downstream side of the first portion with respect to the developer transport direction in the second portion.