| 摘要 |
PURPOSE:To reduce the size of a device and then reduce its cost by setting the reversing speed of a developing roller so that V2>V1, where V1 is the rotating speed at the time of insufficient napping and V2 is the rotating speed at the time of toner supply. CONSTITUTION:Developing sleeves 3b of respective development parts 9, 10, and 11 all rotate forward at the time of development and then reverse. When a toner concentration sensor decides whether or not toner needs to be supplied and it is decided that the toner need not be supplied, they are stopped after only an insufficient napping process of the rotating speed V1. When the toner needs to be supplied, they continue reverse rotation at the rotating speed V2. At this time, the toner concentration sensor keeps on performing detection and the toner supply is carried on until reference toner concentration is reaches. Thus, the reversing speed is set in two stages of V1 and V2 (V2>V1) to make the supply amount of toner very small at the time of insufficient napping as compared with the supply amount of toner at the time of normal toner supply operation, so there is not such trouble that the toner concentration exceeds the reference toner concentration in normal copying operation.
|
