ELECTRIFICATION CONTROLLING METHOD OF PHOTOSENSITIVE BODY

PURPOSE:To correct a drop of an electrifying potential of a photosensitive body, when copying a lot of sheets, by increasing a voltage applied to a discharger, as an exponential function, in accordance with a time from a start of copying. CONSTITUTION:When a power source (a) of a copying machine is turned on, a counter is reset (b). When a copy switch (d) is turned on and copying is started, a time lapse is measured by the counter. A power supply voltage of a corona discharger is increased as an exponential function against a lapse time measured value of the counter, from the first value. As for a photosensitive body, the electrifying efficiency drops due to a fact that a charge is trapped to an energy level, therefore, when the electrifying efficiency is raised as the time elapses, it is corrected. The trap of the charge increases as an exponential function, and there are various time constants thereof, therefore, the voltage rise is executed based on a relational expression consisting of the sum of exponential functions of two kinds of more.