US Patent 7978997 Developer cartridges, process cartridges, and image formation devices

When a developer cartridge is not attached to an image formation apparatus body frame, a developer electrode included with the cartridge is disposed at a retract position at which the developer electrode does not protrude outside the cartridge. This protects the developer electrode from damage possibly caused by interference or contact with other components. After the developer cartridge is attached to the body frame, when the developer roller is rotated, the developer electrode is displaced to a connection position at which the developer electrode protrudes outside the cartridge (and is connected to a power supply electrode provided with the body frame).