| 摘要 |
PURPOSE:To switch a toner replenishment control action from a video counting system to an inductance detecting system at prescribed timing. CONSTITUTION:An inductance head 20 detecting the apparent magnetic permeability of a two-component developer and converting it into an electrical signal, is installed on the bottom wall of the first room of a developing unit 44, and an inductance detecting system developer concentration controller detecting the actual toner concentration of the developer 43 in the developing unit 44 with an output signal from the inductance head 20, and replenishing toner, and a video counting system developer concentration controller estimating/ replenishing the toner based on the number of video counts obtained by integrating the output levels of each picture element of a picture signal, are provided When a copying action is started, the toner is replenished in the video counting system, and when it is detected that the apparent magnetic permeability of the two-component developer is stabilized, the switching to the inductance detecting system is executed, and then, the toner is replenished. |
