| 摘要 |
1481013 Automatic control of electrostatic charging XEROX CORP 29 May 1974 23706/74 Heading G3R The electrostatic charge applied to a movable photo-receptor surface in a copying machine is controlled by regulating either the current received by the photo-receptor, or a current which is arranged to be equal to the photo-receptor current. As shown in Fig. 1, a coronode wire 12 with an earthed shield 13 is connected to a power supply 10 and produces a corona discharge which charges the surface of a photo-receptor drum 14. Current flows from the drum by way of slip rings 15 to a comparator 16 which receives a reference signal and produces a control signal for the power supply 10 to keep the current at the desired value. In an alternative embodiment, Fig. 2 (not shown), current flowing to the comparator 16 from the shield 13 and the supply is regulated, while the photo-receptor 14 is earthed. A device may be included for measuring the residual voltage on the drum 14 and inhibiting the charging process if the measured voltage exceeds say 10 volts. A further sensor may be used to prevent charging if illumination used to discharge the drum surface is not present. Two or more coronodes may be used for charging the drum.
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