US Patent 7835672 Developing device, image carrier unit and image forming apparatus

A developing device includes a first developer containing chamber, a second developer containing chamber, a first inflow section, a second inflow section, a first conveyance member and a second conveyance member. The first inflow section allows the developer to flow from the second developer containing chamber into the first developer containing chamber. The second inflow section allows the developer to flow from the first developer containing chamber into the second developer containing chamber. The first conveyance member conveys the developer contained in the first developer containing chamber in a first developer conveyance direction. The second conveyance member conveys the developer contained in the second developer containing chamber in a second developer conveyance direction. In a range corresponding to the first inflow section, an area of a cross section, perpendicular to the second developer conveyance direction, of the second developer containing chamber decreases along the second developer conveyance direction.