DEVELOPING DEVICE AND IMAGE FORMING APPARATUS

摘要

The present invention provides a developing device and an image forming apparatus capable of carrying out excellent image formation for a long period by making the fluctuations in the toner concentration and the volume level of the developer inside a trickle developing device that uses a two-component developer as small as possible. The developing device having stirring members for conveying and stirring a developer-tank-contained developer and a developer holder, comprises a developer replenishing tank; a toner concentration detecting sensor; a trickle discharging mechanism; developer amount detecting means; and control unit for controlling the replenishment operation of replenishment toner and carrier at the time when the toner concentration is lower than a predetermined reference toner concentration, wherein the control unit carries out forced consumption operation for the toner inside the developer tank and replenishment operation for the replenishment toner and carrier in the case that the amount of the developer-tank-contained developer inside the developer tank is judged to be low using the developer amount detecting means.