Electrification electric potential control unit null of exposure to light

摘要

PURPOSE:To control an electrostatically charged potential without receiving the influence of variance in a photosensitive body and without using any special device such as an electrometer by providing a detecting electrode on the down stream side of the coronode of a charger, detecting the current flowing in a constant voltage element and controlling a high voltage for charge. CONSTITUTION:The high voltage from a high voltage power source 5 is impressed to the coronode 2 of a charger 1, by which a photosensitive body 6 is charged. The value near the final value of the charged potential is detected with a detecting electrode 4 provided on the down stream of the coronode 2. The current corresponding to the charged potential of the photosensitive body is supplied via a constant voltage element 7 connecting to the electrode 4 and a resistor 8 to the comparator circuit 9 of the power source 5 and is compared with set current. The high voltage from the power source 5 is controlled and the charged potential of the photosensitive body 6 is feedback-controlled. The charged potential is thus controlled in accordance with the value near the final value of the charged potential which is less influenced by the variance in the photosensitive body without using any special device such as an electrometer or the like.