| 摘要 |
PURPOSE:To make the fluctuation width of toner concentration extremely small by stepless changing the voltage to be applied to a toner recovery roller to the applied voltage to recover the difference between the toner amount being consumed and replenishment amount thereby controlling the toner concentration. CONSTITUTION:An image density detecting part 13 consisting of a lamp and reflecting density detector which detect original density prior to copying is disposed below the original platen and is so arranged that the detection signal thereof is inputted to a voltage control part 16 to vary the voltage of a toner recovery power source 36. It is so constituted that the voltage corresponding to the reflecting density of the original 8 detected with the detecting part 13, i.e., a low voltage for the images of a high density and a high voltage for the images of a low density are changed stepless and applied to the recovery roller 32. By controlling the toner concentration with adequate toner recovery amount in this way, the fluctuation width of the toner concentration may be made extremely small. |
