| 摘要 |
PURPOSE:To eliminate the need for an adjustment operation by automatically determining a reference level by the output of a sensor with respect to a developer having an actually specified concn. CONSTITUTION:The output level Vs of the toner concn. detecting sensor 35 provided to a developing device 3 and the reference level Vr are compared by a control part 7 and the toner replenishment of the developing device 3 is controlled by the result of the comparison. The output level of the toner concn. detecting sensor 35 at the time of charging the developer is read and the value of the reference level Vr is determined by the output level. The exact control of the toner concn. is thus enabled even if the adjustment operation is not carried out at the time of charging the developer. |
