| 摘要 |
PURPOSE:To increase the circulating efficiency of a developer, to make the diffusivity of toner excellent and moreover, the quantity of developer passing the detecting part of a developer concentration measuring device less and to improve detecting accuracy. CONSTITUTION:Two sub-carrying paths for the developer 6 and 7 are provided in the adjacent to a main developer carrying path 5, so that the developer carried from the central part to both end sides or from both end sides to the central part on the main developer carrying path 5 is divided and supplied to the sub-carrying paths for the developer 6 and 7 and returned to the main developer carrying path 5 while being carried in the direction opposite to the main developer carrying path 5 by these carrying paths for the developer 6 and 7 and the concentration of the developer can be measured by the developer concentration measuring device 13 provided on one sub-carrying path for the developer 7. |
