| 摘要 |
<P>PROBLEM TO BE SOLVED: To always stabilize a charging voltage applied for charging an image carrier by a charging part, in particular, to improve image quality by preventing fog caused by a charging voltage decrease. <P>SOLUTION: A first reference voltage is set as an application voltage to a charging roll 56 that is highly likely to cause fog. The application voltage is shifted in the direction in which fog is removed gradually (in the direction in which the absolute value of the voltage is decreased), to the level at which fog is securely prevented. The density of a non-image formation area is detected in each step. The application voltage at which a difference between this density and the density obtained by the application of the first reference voltage exceeds the predetermined density threshold value of fog density is set as a second reference voltage. By making a correction based upon the present environment, the application voltage suitable for the present environment can be set. Accordingly, the appropriate application voltage for the charging roll 56 can be obtained taking account of both an environmental change and a change with time. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
