| 摘要 |
PURPOSE:To keep the surface potential of a photosensitive drum constant and further to always obtain an excellent copied image by controlling impressed voltage on in electrostatic charging member (electrostatic charging roller) so that the surface potential of the photosensitive body may approximate to a set value based on a film thickness changing signal. CONSTITUTION:This device is constituted of the electrostatic charging roller 7 which is provided to abut on the surface of the photosensitive drum 1, a variable DC power source 10 which impresses variable voltage on the roller 7, a copying counter 11 which outputs information signal being the number of papers where copying is performed as the film thickness changing signal and a microcomputer 12 in which the film thickness changing signal is inputted from the counter 11 so as to control the voltage impressed on the roller 7 from the power source 10. Then, the microcomputer 12 corrects the impressed voltage on the roller 7 so that the surface potential of the photosensitive drum 1 may approximate to the set value with the input of the film thickness changing signal from the counter 11. |
