Development agent supply device including an electric-field transfer board and a development agent retrieving unit and image forming apparatus having the same

An image forming apparatus comprising:

• a photoconductive body configured such that a development agent image is formed thereon;
• and
• a development agent supply device configured to supply charged development agent to the photoconductive body,
• wherein the development agent supply device comprises:
• a development agent holding member that comprises a development agent holding surface formed to be a cylindrical circumferential surface parallel to a main scanning direction, the development agent holding member being configured to rotate around an axis parallel to the main scanning direction such that the development agent holding surface moves in a moving direction perpendicular to the main scanning direction and faces the photoconductive body in a development agent supply position;
• a casing formed to, when viewed in the main scanning direction, be elongated in a longitudinal direction that is substantially perpendicular to the main scanning direction and parallel to a horizontal direction,
• wherein the casing comprises:
• an opening formed at a first end in the longitudinal direction of the casing;
• a first development agent storage section that is formed at a second end in the longitudinal direction in a bottom region of an internal space of the casing and configured to store development agent;
• and
• a second development agent storage section that is formed in a position adjacent to the first development agent storage section in the bottom region of the internal space of the casing and configured to store development agent, and
• wherein the casing accommodates the development agent holding member such that the development agent holding surface faces the photoconductive body via the opening;
• a first electric-field transfer board comprising a development agent transfer surface facing down, the first electric-field transfer board being configured to transfer development agent with a traveling-wave electric field, along the development agent transfer surface in a development agent transfer direction that extends from the first development agent storage section to the opening, while making inadequately-charged development agent fall from the development agent transfer surface, the first electric-field transfer board facing the development agent holding surface at a downstream end in the development agent transfer direction so as to supply adequately-charged development agent to the development agent holding surface;
• and
• a development agent retrieving unit configured to agitate the development agent stored in the second development agent storage section and the inadequately-charged development agent falling from the development agent transfer surface and convey the agitated development agent to the first development agent storage section, the development agent retrieving unit comprising a first and second auger each comprising a shaft formed along the main scanning direction and a corkscrew blade formed around the shaft, the first auger being configured to rotate around the shaft and to move the development agent in the second development agent storage section in a first direction along the main scanning direction, the second auger being disposed parallel to the first auger and adjacent to the first auger in the longitudinal direction of the casing, the second auger being configured rotate around the shaft and to move the development agent in the second development agent storage section in a second direction opposite to the first direction.