Developing Device and Image Forming Apparatus Having the Same

An image forming device comprising:

• a casing;
• a support frame configured to be drawn from the casing;
• a plurality of cartridges configured to be detachably supported by the support frame, each of the cartridges comprising
• a developing member having an outer surface configured to carry a developing agent;
• a supply member configured to supply the developing agent to the outer surface;
• a developing agent container disposed below the developing member and the supply member and having an inner surface defining an internal space for accommodating the developing agent, the developing agent container being formed with an opening having an upper edge and a lower edge;
• and
• a conveying member rotatably disposed in the internal space and configured to convey the developing agent upward;
• wherein the developing agent container includes a first wall portion extending from the lower edge in a downstream direction with respect to a rotational direction of the conveying member and also includes a second wall portion extending from the upper edge in an upstream direction with respect to the rotational direction;
• and
• wherein the conveying member is configured to be in simultaneous sliding contact with both the lower edge and the upper edge to convey the developing agent onto the first wall portion.