| 摘要 |
PURPOSE:To miniaturize and simplify the developing device by providing a toner concentration sensor detecting the toner concentration of the developer inside the developer container in an empty space on the start developer container case side. CONSTITUTION:The container case CS containing the start developer and a toner cartridge CT for toner replenishing are each mounted on top of a developing tank part 41 and a hopper part 42. The toner concentration sensor 25 consisting of a magnetic sensor, etc., is attached to an opening part 22a side in the approximate central position in the longitudinal direction of the container case CS. Therefore, when the container case CS is mounted on the developing tank part 41, detection signal of the toner concentration sensor 25 is inputted to a control part 29, and the toner concentration inside the developing tank part 41 can be controlled. That is, since the initial developer is fed to the developing device 4 by the container case CS and the space for the container case CS becomes a dead space after it is mounted on the developing tank part 41, the toner concentration sensor 25 is provided utilizing this space. |
