Image forming apparatus with developer density and developer remaining amount detection features

摘要

An image forming apparatus has a developing device for developing an electrostatic image formed on an image bearing member by a developer. A developer supplying unit is detachably attachable to a main body of the image forming apparatus and supplies the developer to the developing device. A density detecting device detects a density of the developer in the developing device. A developer remaining amount detecting device detects information regarding an amount of the developer in the developing supplying unit. A state of the developer supplying unit is judged on the basis of a result of the detection by the density detecting device and a result of the detection by the second detecting device.