| 摘要 |
PURPOSE:To maintain a good and constant developing density in all the times, by controlling the flow rate of a toner with a flow rate regulating plate according to an environmental change and controlling a developing bias voltage by measuring the developing bias current. CONSTITUTION:When the temp. is risen by the effect of an actuator 16, the gap (d) between a flow rate regulating plate 17 for a toner and a sleeve 2 is narrowed to decrease the flow rate of a toner 4. When the temp. is lowered, the gap (d) is widened to increase the flow rate of the toner 4. Since developing bias current IB and developing density are made proportional by the above- mentioned control, the apparent electric resistance of the toner 4 changes and the current IB is so regulated as to make the developing density constant. The change in the current IB flowing in a developing device 12 by the effect of temp. and humidity is detected with a current change detector 21 and the developing bias voltage VB is changed by a voltage control device 22 according to the signal obtained by said detection, by which change in the current IB is reduced and the developing density is maintained constant. |
