| 摘要 |
PURPOSE: To control the discharge quantity of developer overflowing from a developer discharge apertrue and to stabilize the concentration of the developer by providing an up-and-down moving means for moving the position of the developer discharge aperture up and down and a quantity detecting means for detecting the developer quantity inside a developing tank. CONSTITUTION: An agitator existing forward in the shaft direction of a developing roller 17 is provided with a cylindrical port part 23 at its end. The developer discharge aperture 23a is formed on the side wall of the port part 23. The aperture 23a is formed to be circular and can be rotated with center at a cylinder shaft. Thus, the position of the aperture 23a is moved up and down so as to adjust the discharge quantity of the developer. The developing tank 16 is provided with a toner concentration sensor 34 functioning as the quantity detecting means for detecting the toner concentration in the developing tank. The detection signal of the sensor 34 is outputted to a controller 32, so that toner and carrier developer in a developer supply unit is supplied. |
