| 摘要 |
PURPOSE:To invariably set the toner density to a proper value even when the developer quantity in a developing tank is changed and maintain good image quality. CONSTITUTION:A carrier developer containing a carrier is supplied from a carrier developer storage chamber 20b to substitute the deteriorated developer constituted of the toner and carrier in a developing tank 16 in sequence, and the developer quantity corresponding to the supply quantity is discharged from a discharge opening 26 in this developing device. The developer quantity in the developing tank 16 is detected, and the toner density is controlled by the proper value of a toner density sensor 25 based on the relationship between the developer quantity and magnetic permeability sensor value. |
