| 摘要 |
PURPOSE:To make the concentration of a toner in a developer correct based on a detection of an exact toner concentration, by inputting a forced toner replenishing switch and executing a toner replenishment while performing a stirring operation until a detected value of the toner concentration reaches a set value. CONSTITUTION:When a forced toner replenishing switch 91 is inputted, stirring of a developer in a developing vessel 45 is started. Subsequently, whenever a toner replenishment is executed by a prescribed quantity, a toner concentration is detected after stirring. That is, the toner concentration in the developing vessel 45 is always detected after a bias of the toner concentration of the devel oper in the developing vessel 45 is reduced or obviated. Especially, a bias of the toner concentration generated when a toner carrying path extending from a toner bottle 43 to a developing sleeve 42 is long is prevented. In such a way, the toner replenishment based on a detection of an exact toner concentration can be executed. |
