Developer cartridge, developing unit and image forming apparatus including the same

A developing unit comprising:

• a developer cartridge comprising:
• a cartridge cabinet comprising:
• a wall surface;
• a developer accommodate chamber that accommodates developer;
• a supply opening that is provided in the wall surface and supplies the developer from an inside of the developer accommodate chamber to an outside of the developer accommodate chamber;
• and
• a return opening that is provided in the wall surface and returns the developer from the outside of the developer accommodate chamber to the inside of the developer accommodate chamber,
• wherein the developer cartridge further comprises:
• a rotational shaft that is rotatably supported in the cartridge cabinet, extends parallel to the wall surface and penetrates through the inside of the developer accommodate chamber;
• a first agitating blade that is attached to the rotational shaft to rotate with the rotational shaft and that is located in a position opposed to the return opening, a distance from the rotational shaft to an distal end of the first agitating blade being shorter than a distance from the rotational shaft to the return opening in a region overlapping the return opening;
• and
• a second agitating blade that is attached to the rotational shaft to rotate with the rotational shaft and that is located in a position opposed to the supply opening, a distance from the rotational shaft to a distal end of the second agitating blade being longer than a distance from the rotational shaft to the supply opening, and
• wherein the developing unit further comprises a unit cabinet which is attachable to and detachable from the developer cartridge, the unit cabinet comprising:
• a developing chamber;
• a plurality of openings that are provided in a wall surface of the unit cabinet, a respective one of the plurality of openings located in a position opposite to the supply opening and the return opening of the developer cartridge enable communication between an inside of the developing chamber to the inside of the developer accommodate chamber;
• and
• a developer transport member that is provided inside the developing chamber and transports developer supplied from the supply opening to the inside of the developing chamber in a direction along the rotational shaft.

An image forming apparatus comprising:

• an apparatus body comprising:
• a developing unit comprising:
• a developer cartridge comprising:
• a cartridge cabinet comprising:
• a wall surface;
• a developer accommodate chamber that accommodates developer;
• a supply opening that is provided in the wall surface and supplies the developer from an inside of the developer accommodate chamber to an outside of the developer accommodate chamber;
• and
• a return opening that is provided in the wall surface and returns the developer from the outside of the developer accommodate chamber to the inside of the developer accommodate chamber,
• wherein the developer cartridge further comprises:
• a rotational shaft that is rotatably supported in the cartridge cabinet, extends parallel to the wall surface and penetrates through the inside of the developer accommodate chamber;
• a first agitating blade that is attached to the rotational shaft to rotate with the rotational shaft and that is located in a position opposed to the return opening, a distance from the rotational shaft to an distal end of the first agitating blade being shorter than a distance from the rotational shaft to the return opening in a region overlapping the return opening;
• and
• a second agitating blade that is attached to the rotational shaft to rotate with the rotational shaft and that is located in a position opposed to the supply opening, a distance from the rotational shaft to a distal end of the second agitating blade being longer than a distance from the rotational shaft to the supply opening, and
• wherein the developing unit further comprises a unit cabinet which is attachable to and detachable from the developer cartridge, the unit cabinet comprising:
• a developing chamber;
• a plurality of openings that are provided in a wall surface of the unit cabinet, a respective one of the plurality of openings located in a position opposite to the supply opening and the return opening of the developer cartridge enable communication between an inside of the developing chamber to the inside of the developer accommodate chamber;
• and
• a developer transport member that is provided inside the developing chamber and transports developer supplied from the supply opening to the inside of the developing chamber in a direction along the rotational shaft.