| 摘要 |
PURPOSE:To charge a photoreceptor to a stable potential for a long time, by providing a grid electrode between a corona electrode and the photoreceptor and connecting a variable resistor and a constant voltage passive element in series to the grid electrode and grounding the constant voltage passive element. CONSTITUTION:A corona electrode 4 connected to a DC high voltage source 3 is provided in a conductive shield 1 provided for a photoreceptor 2. A grid electrode 5 is provided between the corona electrode 4 and the photoreceptor 2, and a variable resistor 6 and a constant voltage passive element 7 are connected directly to the electrode 5, and the element 7 is grounded. When the bias voltage of the grid electrode 5, the constant voltage value of th passive element 7, the voltage generated in the resistor 6, and th voltage accumulated on the surface of the grid electrode are denoted as Vg, Vt, Vr, and Vm respectively, expression is true. The voltage Vm rises in accordance with the number of times of corona discharge, and the resistance value of the variable resistor 6 is adjusted in accordance with this rise to obtain the always constant bias Vg, thereby obtaining a stable image for a long time. |
