| 摘要 |
PURPOSE:To eliminate the photographic fog phenomena at the leading end of copies and the developing of excess toners on a photoreceptor by connecting a diode and a switching circuit in parallel and providing the same between a developing roll and a bias power source. CONSTITUTION:A switching circuit 10 is connected in parallel with a diode 4 provided between a developing roll 2 and a bias power source 3. With such arrangement, the switch 11 of the circuit 10 is turned on only at the rising for developing to connect the power source 3 and the roll 2 directly so that the effect of bias voltage is received during the flow of counter charge 7 in a capacitor 9. After the capacitor 9 is charged, the switch 11 of the circuit 10 is turned off to connect the roll 2 and the power source 3 via the diode 4 so that the injection of the electric charge in the direction where the potential of the photoreceptor surface is neutralized from the power source 3 is prevented by the diode 4. Thus the generation of photographic fog phenomena is prevented. |
