| 摘要 |
PURPOSE:To always keep the concentration of toner in developer constant by continuously supplying replenishment toner when abnormal drop in toner concentration is detected. CONSTITUTION:When a detection voltage from a toner concentration sensor 11 exceeds reference voltage data, that is, when remarkable drop in the concentration of toner in the developer is detected, the operation is switched to a forced replenishment mode in which toner replenishment is continuously performed. A control circuit 22 transmits a forced replenishment command signal to a driver circuit 20; the driver circuit 20 transmits a driving signal to motors M1 and M2 to drive them; consequently, a toner carrying part 5 and a replenishment roller 6 are driven, and toner replenishment continues until the toner concentration reaches a normal toner concentration. Thus, the concentration of toner included in the developer in a developing vessel 4 can be always maintained at the normal toner concentration value. |
