| 摘要 |
PURPOSE:To obtain a small-size device with high responsibility and reliability which operates properly according to recording operation condition by controlling a voltage applied to a grid electrode to below a voltage which includes the earth voltage and has the same polarity with a discharge current. CONSTITUTION:The high voltage of a high voltage power source HV is applied to the discharging wire 2 of an electrostatic charger 1 and a negative voltage which includes the ground voltage and has the same polarity with the discharge current is applied to the grid wire 4 from a bias power source 9, and they are controlled by a bias power source adjusting device 9. The device 9 controls the voltage applied to the wire 4 and a bias voltage to a developing device 10 according to the recording operation condition of an original, a photosensitive body, etc. Therefore, the need for two power sources which differ in polarity and a changeover switch is eliminated and the control is performed according to the recording operation condition to control the image part of the photosensitive body to a potential corresponding to a copy with high reproducibility and the no-image part to a potential at which no toner is stuck. |
