| 摘要 |
PURPOSE:To prevent a deflection of the toner concentration and then a deflection of the copy concentration, by supplying a larger amount of toner to the developing region in response to the size of the transfer paper as well as the image forming region. CONSTITUTION:When a reduction is detected for the concentration of a developer by a concentration sensor, a screw conveyor 8 is turned by a DC motor 17. Thus a toner 14 in a hopper 15 is carried to a supply pipe 7 and mixed with a developer supplied through a hole 7a to drop into a tank. The distribution of the dropped toner quantity varies to each position in the axial direction. If the number of revolutions of the motor 17 is set as N1>N2>N3, the quantity of the supplied toner becomes uniform with N3. Then the toner quantity of the right side decreases toward N2 and N1. Therefore the image forming region is set at the left edge of a development tank in case the copying is carried out from the maximum size to a smaller size. Thus a larger amount of toner can be supplied to the image forming region in an approximately uniform way by increasing the number of revolutions of a driving motor, i.e., the conveyor 8. |
