| 摘要 |
PURPOSE:To properly control toner concentration and to stably form effective images even at the slow carrying speed of a developer by allowing only a sleeve to be optionally rotated and allowing a detection means for detecting a developer retainer formed by a doctor member to interlock with a magnetic toner feeding means. CONSTITUTION:A magnetic carrier means 4 is constituted of the sleeve 7 and a permanent magnetic member 8 arranged coaxially with the sleeve 7 and the sleeve 7 is formed so as to be optionally rotated. When the toner density of a developing material 11 on the sleeve 7 in a developing area is proper, the quantity of a developer bank 11a formed by the doctor member 10 is held at a prescribed value and the feeding of excess magnetic toner 2 is stopped, and only when the quantity of the retainer 11a is less than the prescribed quantity, a feeding means 6 for feeding the magnetic toner 2 stored in a toner retainer 1 is driven by a signal outputted from a detecting means 12. Consequently, the developer 11 can be carried at a slow speed, the toner concentration can be controlled to proper value and effective images can be stably formed. |
