| 摘要 |
PURPOSE: To keep the surface potential of a photoreceptor constant, without being affected by a change in the temperature and humidity of an atmospheric environment and reduction in the film of the photoreceptor. CONSTITUTION: At least two kinds of voltages are selectively impressed from a power source 4 to an electrifying roller 2 in contact with or proximity to the moving photoreceptor 1 and currents generated by first and second voltages impressed to the electrifying roller 2 are measured by a current measuring means 11. A control means 10 inputs/stores the values of the measured currents and makes a calculation based on the voltages impressed to the electrifying roller 2, the currents measured by the current measuring means 11 and a previously measured resistance value from the power source 4 to the electrifying region of the roller 2. An optimum voltage impressed to the roller 2 for making the photoreceptor 1 in an image forming process a desired potential is set and the power source 4 is controlled so as to impress the optimum voltage to the roller 2. |
