Developing device and image forming apparatus including same

A developing device comprising:

• a developing container which includes a first conveyance chamber and a second conveyance chamber arranged above the first conveyance chamber, and contains a developer which contains a toner;
• a first stirring-conveyance member which is rotatably supported in the first conveyance chamber, and conveys the developer in the first conveyance chamber in a first direction, while stirring the developer;
• a second stirring-conveyance member which is rotatably supported in the second conveyance chamber, and conveys the developer in the second conveyance chamber in a second direction opposite to the first direction, while stirring the developer;
• and
• a developer carrier which is rotatably supported in the developing container, and carries on a surface thereof the developer in the first conveyance chamber or the second conveyance chamber,
• wherein
• the developing container further includes
• a partition section which divides the first conveyance chamber and the second conveyance chamber from each other,
• a first communication section which allows the first conveyance chamber and the second conveyance chamber to communicate with each other at downstream-side end portions thereof in the first direction, and
• a second communication section which allows the first conveyance chamber and the second conveyance chamber to communicate with each other at downstream-side end portions thereof in the second direction,
• the first stirring-conveyance member includes
• a rotary shaft,
• a plurality of spiral blades which are formed on an outer peripheral surface of the rotary shaft, and
• a reverse spiral blade which is arranged downstream of the plurality of spiral blades in the first direction so as to face the first communication section, and which is opposite in winding direction to the plurality of spiral blades,
• downstream ends of the plurality of spiral blades in the first direction are located substantially equally distant from the reverse spiral blade,
• the reverse spiral blade includes a plurality of reverse spiral blades of a number equal to a number of the plurality of spiral blades, and
• upstream ends of the reverse spiral blades are each located opposite to, and at an equal distance from, a corresponding one of the downstream ends of the plurality of spiral blades.