| 摘要 |
PURPOSE:To obtain a maintenance-free developing device by constituting the electrostatic charging sequence of material of the insulating layer of a metallic roll for removing different color toner entering the 2nd developing device selectively among materials positioned in a predetermined array. CONSTITUTION:The metallic roll 6 is charged to the positive polarity by friction with the 2nd carrier of the 2nd developer, and has nearly the same potential with the 2nd toner and only stirs it. If the 2nd black toner 5c having the opposite polarity is mixed, the 1st toner sticks to the roll 6 easly. This 1st sticking toner 5c is scraped off with a following blade 7 and recovered by a spiral roll 8. In this case, when the charging sequence is at a position adjacent to the 2nd toner, the 2nd toner does not stick to the roll any more, and a waste of the 2nd toner is further reduced. |
