| 摘要 |
PURPOSE:To suppress the scattering of a developer occurring when copying is started and the excess of a concentration and simultaneously, to eliminate the lack of the developer when the consumption of the developer is great by providing a measuring means measuring the concentration of the developer on the upstream and downstream sides of a developer supplying part. CONSTITUTION:The means 46 and 47 measuring the concentration of the toner on the upstream and downstream sides of the developer supplying part 38a are provided while adjoining it to the developer supplying part 38a. Then, in the initial and final stages of a consecutive developing action, the concentration of the toner on the downstream side of the developer supplying part 38a is measured by the measuring means 47, and controlled based on the concentration of the toner before it is consumed as the basis of developer concentration control. On the other hand, in a middle stage, the concentration of the toner on the upstream side is measured by the measuring means 46, and is controlled based on the concentration of the developer after it is consumed as the basis of the developer concentration control. Thus, the scattering of the toner and the excess of the concentration are suppressed without making the quantity of the toner supplied to the developing sleeve 32 excess, and a sufficient developer is supplied even if the consumption of the developer on the developing sleeve 32 is large. |
