| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing apparatus using a trickling system, configured to maintain toner concentration in a developing unit within a predetermined range even if carrier different in volume density from that of carrier in the developing unit is supplied to the developing unit.SOLUTION: A presence ratio of second carrier in a developing unit 20, the carrier being supplied from a developer bottle B to the developing unit 20, is calculated. On the basis of the calculated presence ratio of the second carrier, correlation between a value detected by a magnetic permeability sensor S1 and toner concentration in the carrier in the developing unit 2 is calculated. A value to be set in the magnetic permeability sensor S1 is corrected so that the toner concentration in the developing unit 20 is equal to a predetermined value. |
