| 摘要 |
PURPOSE:To control toner concentration with high accuracy under a simple constitution by providing a signal processing means which processes an output that comes from a sensor disposed in each developing unit and varies with the permeability of a developer, based on a prescribed, adjusted value. CONSTITUTION:In a developing device employing a two-component developer, each developing unit 2 is provided with the sensor 8 which outputs an electrical signal varying with a change in the permeability of the developer. A signal from the sensor 8 is output to the signal processing means, which processes it based on a prescribed, adjusted value. This adjusted value is set for each developer so that the output of the signal processing means comes to a prescribed reference value. Namely, the output value of a signal processing part is compared with the reference value for each developer, and toner is supplied to each developer 2 according to the difference. Thus, toner concentration is surely controlled even if the sensors and the developing units have variance. |
