Developing agent circulation system and image forming apparatus using same

摘要

A development agent circulation unit includes a development unit, an agitation unit, and a rotary feeder. The development unit develops a latent image on an image carrier using a developing agent. The agitation unit agitates developing agent recovered from the development unit. The rotary feeder receives the developing agent from the agitation unit and discharges the developing agent in predetermined discrete amounts. The discharged developing agent is transported to the development unit using a gas stream. The rotary feeder includes a rotor and a stator having a clearance “t” between the rotor and the stator. The clearance “t” satisfies a relation “t<2D” where D denotes a developing agent particle diameter, and a toner particle diameter dt of a toner particle of the developing agent and a carrier particle diameter dc of a carrier particle of the developing agent satisfy a relation D=dc+2dt.