Patent ID: 7907874

Claim:
A development device comprising: developer composed of toner and carrier; a development unit which includes a developer housing room in which the developer composed of toner and carrier is housed, a developer agitating and transporting member in the developer housing room, and a developer bearing member which can bear and transport the developer agitated and transported by the developer agitating and transporting member; supply toner; and a toner supply unit which includes a toner supply room in which at least the supply toner is housed, a toner transporting member in the toner supply room, and a toner supply port, wherein the toner supply room communicates with the developer housing room of the development unit through a toner supply port, wherein the toner supply port of the toner supply unit opens so that its lower end is located in a lower position than a surface position of the developer positioned at a position contacting with the toner supply port and housed in the developer housing room; wherein press power by which the supply toner in the toner supply unit is pushed out from the toner supply port is larger than the internal pressure of the developer in the developer housing room; wherein the toner supply room includes a dispensing room which is formed at the portion faced to the toner supply port and can supply the supply toner quantitatively, a dispensing member for quantitative supply as a toner transporting member in the dispensing room, and includes a dispensing room entrance opening at a communication portion with the dispensing room, and wherein the dispensing member is an auger provided with an agitating and transporting vane and a vane for weir around a rotation shaft of the auger; wherein the lower end of the toner supply port is located in a position lower than a rotation center of the developer agitating and transporting member; wherein the toner supply port of the toner supply unit communicates the dispensing room of the toner supply unit with the developer housing room of the development unit; wherein the toner supply port of the toner supply unit opens at a position which faces a boundary between the agitating and transporting vane provided in the dispensing member and the vane for weir provided in the dispensing member.