| 摘要 |
PURPOSE:To prevent erroneous detection by a toner concentration sensor by driving at least either a developing sleeve or a stirring rotor at the time of initially driving a developing device at a lower speed than the normal revolving speed at the time of developing. CONSTITUTION:At the time of initially driving the developing device, at least either the developing sleeve 2 or the stirring rotor 3 is driven at the lower sped than the normal revolving speed at the time of developing. Therefore, the supply amount of developer to a toner concentration sensor side by the developing sleeve is reduced. When the supply amount of the developer to the toner concentration sensor S side is reduced, the developer circulates on a partition plate without contacting to the sensor S, or even though the developer contacts to the sensor S, the amount of the developer becomes a little. Thus, a situation that the toner concentration of the developer in which magnetic permeability becomes high is erroneously detected unexpectedly by the toner concentration sensor is evaded. |
