Patent ID: 7856196

Claim:
A developing device comprising: a developer holding member that carries a developer comprising a carrier and a toner; an upper developer housing section that houses the developer to be supplied to the developer holding member; a lower developer housing section that is adjacent to the upper developer housing section; has a bottom surface lower than a bottom surface of the upper developer housing section in a direction of gravitational force; and houses the developer to be supplied to the upper developer housing section; a toner supply section that comprises: an upper toner supply part that is disposed in one end of a shaft of the upper developer housing section; and defines a toner supply opening on an upper side thereof, the toner being supplied from the toner supply opening into the upper toner supply part; a lower toner supply part that is disposed in one end of a shaft of the lower developer housing section, which is the same side as the one end of the shaft of the upper developer housing section; and supplies the toner to the lower developer housing section; and a toner transport section that transports the toner from the upper toner supply part to the lower toner supply part; an upper conveying section that is disposed to extend over the upper developer housing section and the upper toner supply part; and comprises: a rotation shaft; a first conveying member that conveys at least one of the developer and the toner in a shaft direction of the rotation shaft; a second conveying member that is disposed on an end portion on a downstream side in a conveying direction of at least one of the developer and the toner by the first conveying member; and conveys at least one of the developer and the toner in a direction opposite to the conveying direction by the first conveying direction; and a diameter direction conveying part that is disposed in an area corresponding to the toner transport section in the shaft direction of the rotation shaft; and conveys the supplemental toner by applying a conveying force to the supplemental toner, the conveying force being larger in the diameter direction larger than in the shaft direction of the rotation shaft of the upper conveying section; a lower conveying section that is disposed to extend over the lower developer housing section and the lower toner supply part; rotates such a manner that the lower conveying section passes a bottom side of the lower developer housing section, a side of the upper developer housing section and an upper side of the lower developer housing section in this order; and thereby conveys at least one of the developer and the toner in a direction opposite to the conveying direction by the first conveying member; and a third conveying member that is disposed between the first conveying member and the diameter direction conveying part; conveys the developer in the same direction as the conveying direction by the first conveying member; and has a diameter smaller than the first conveying member.