DEVELOPING DEVICE AND DEVELOPING DEVICE ATTACHABLE IMAGE FORMING DEVICE

摘要

PROBLEM TO BE SOLVED: To detect toner residual amount continuously at low cost by detecting the amount of current flowing in a developing roller when consumed toner is moved from the developing roller to a toner image carrier. SOLUTION: Electrostatic charged toner 12 is moved from the developing roller 8 to the toner image carrier 1 by an amount served for development due to a difference between developing voltage by a power source 14 and the surface potential of the toner image carrier 1. Then, by moving the toner 12 charged in such a way, the current in proportion to the amount of the moved toner 12 flows in the roller 8. The current flowing in the roller 8 is measured by a current measuring part 13. When the current flowing in the roller 8 is measured, toner consumed amount is obtained by arithmetic operation in a toner consumed amount arithmetic operation part and stored in a toner consumed amount storage part. The toner consumed amount is subtracted from the toner amount in a developing device 4 till then so as to display the toner residual amount on a toner residual amount display part.