| 摘要 |
PURPOSE:To always reduce the variance of the surface potential of an OPC drum and to improve the quality of an image by boosting the output voltage of an electrostatic charger only in a 1st rotation of the OPC drum. CONSTITUTION:A voltage generated from a high voltage generator 8 is boosted when a resistance value between a point A and the earth is small, and since the resistance value is almost zero, the initial rotation of the photosensitive drum (OPC drum) 3 impressed a high voltage to the charger 9 as shown by B in a figure (a). When a time 4 is controlled so as to output a high level in a 2nd rotation and after, a transistor(TR) 6 is turned off by a signal obtained through an inverter 5 and a resistor 7 is inserted between the point A and the earth. Thereby, a high-voltage generator 8 impresses voltage on the charger 9 as shown by C in the figure (a). Consequently, the surface potential of the drum 3 is fixed independently of the rotation of the OPC drum 3 as shown in a figure (b).
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