| 摘要 |
PURPOSE:To always hold the surface potential of a recording medium at a constant value, and to execute uniform charging at high speed, by detecting the surface potential of the recording medium which has been charged, and suitably controlling the grid voltage of a corona charger in accordance with said surface potential. CONSTITUTION:Surface voltage Vs of a recording medium 5, which has been detected by a surface electrometer 6 is voltage-divided by resistances R1, R2, the potential in its voltage-divided point (a) is compared with a reference voltage value voltage-divided by resistances 3, 4 and a resistance 5, by a comparator CMP, and by its comparison output, a switching transistor Q1 is controlled, and grid voltage Vg is applied to a grid electrode 4 of a corona charger body 1. When a comparison control against the reference value or a feedback control are executed in accordance with the surface potential detected in this way, the grid voltage of the corona charger body 1 is controlled, and the surface potential of the recording medium 5 is made constant. |
