| 摘要 |
PURPOSE: To provide a developing device whose constitution is simple and whose cost is low. CONSTITUTION: This developing device 20 is equipped with a developer storage part 20B independently of a developer stirring part 20A, and is provided with a toner concentration detecting means 3 set in the developer stirring part 20A and detecting toner concentration in accordance with the characteristic of developer 17 carried to the stirring part 20A. In the device 20, whether a new developing unit exists or not is discriminated based on output from the toner concentration detecting means 3. |
