| 摘要 |
PURPOSE:To prevent a large quantity of toner from adhering to an photosensitive drum by connecting capacitors to a developing device in parallel and connecting them to a high voltage power source. CONSTITUTION:Since a control driving part 12 starts oscillation and a transistor Q repeats on/off by turning on a power source switch S1, AC high voltage is generated in the secondary winding W2 of a transformer T and is rectified and smoothed by a voltage doubler rectifier circuit consisting of diodes D1 and D2 and the capacitors C1 and C2 to be impressed on a charger 1. By turning off the power source switch S1 when a printing action is completed, the voltage of the secondary winding S2 of the transformer T lowers and the photosensitive drum is not charged in substance. When a developing switch is turned off, developing bias voltage is impressed on a developing roller 2 with electric charges stored in a capacitor C4 through a constant voltage circuit 11. Therefore, the developing bias voltage impressed on the developing roller does not change for a while even if the voltage generated in the secondary winding W2 of the transformer T lowers. Thus, a large quantity of toner is prevented from adhering to the photosensitive drum 4. |
