| 摘要 |
PURPOSE:To prevent contamination in a machine body caused by the scattering of toner from occurring and to always output a copy having excellent image density in an initial time and through life by providing a varying means for varying a reference value in accordance with the use time of a developing device and the characteristic of developer. CONSTITUTION:The device is constituted of a detection means 48 for detecting the toner concentration of the developer, a control means 60 for controlling the replenishment of the toner T to the developing device 40 according to the compared result which is obtained by comparing an output from the detection means 48 with the reference value, and the varying means 62 for varying the reference value in accordance with the use time of the developing device 40 and the characteristic of the developer. In such a case, the reference value can be shifted with the characteristic of the life of the developer. Thus, the specific concentration of the toner in the developer is kept constant and the contamination in the machine body caused by the scattering of the toner is prevented from occurring, thereby always outputting the copy having the excellent image density in the initial time and through life. |
