Developing device and image forming apparatus including the same

A developing device comprising:

• a developing container partitioned into a stirring-transport chamber, a supplying-transport chamber, and a collecting-transport chamber that are arranged substantially in parallel with one another, for storing a two-component developer including a carrier and a toner;
• a developer carrying member supported rotatably by the developing container, for carrying developer on a surface thereof;
• a supplying-transport member, located within the supplying-transport chamber, for stirring and transporting developer in a transport direction along an axial axis of the developer carrying member and supplying developer stirred and transported thereby to the developer carrying member;
• a stirring-transport member located within the stirring-transport chamber, for stirring and transporting developer in a direction reverse to the transport direction of the supplying-transport member;
• a collecting-transport member located within the collecting-transport chamber, for stirring and transporting developer collected from the developer carrying member in the same direction as the transport direction of the supplying-transport member;
• a first developer passage provided between the supplying-transport chamber and the stirring-transport chamber, for passing developer from the stirring-transport chamber to the supplying-transport chamber;
• a second developer passage provided between the supplying-transport chamber and the stirring-transport chamber, for passing developer from the supplying-transport chamber to the stirring-transport chamber;
• and
• a communication portion provided at a downstream end of the collecting-transport chamber and on an upstream side of the second developer passage in the transport direction of the supplying-transport member, for passing developer from the collecting-transport chamber to the supplying-transport chamber,
• wherein a developer transporting speed of the collecting-transport member differs from a developer transporting speed of the supplying-transport member,
• wherein the collecting-transport member passes developer to the supplying-transport chamber also from a region upstream of the communication portion in the transport direction of the supplying-transport member,
• wherein a clearance is provided along a longitudinal direction of the collecting-transport member above a partition wall that partitions between the collecting-transport chamber and the supplying-transport chamber, and
• wherein the clearance becomes wider from an upstream side toward a downstream side in the transport direction of the supplying-transport member.