| 摘要 |
PROBLEM TO BE SOLVED: To appropriately measure toner concentration in developer by a concentration sensor installed opposite to a stirring member for mixing and stirring the developer even in the case the flowability of the developer is changed due to the environmental change of temperature and humidity, etc. SOLUTION: As for the developing device for rotating the stirring member 14a provided with a stirring blade to mix and stir the developer in the device main body 10 for storing the developer 2 containing the toner and carrier, and also for measuring the toner concentration in the developer by the concentration sensor 17 installed opposite to the stirring member, the ratio of the maximum distance A1 to the minimum distance A0 (A1 /A0 ) at the part where the rotational track of the stirring blade 15c for the stirring member 14a installed opposite to the concentration sensor 17 faces the concentration sensor 17 is controlled to >=1.5. |
