| 摘要 |
PROBLEM TO BE SOLVED: To prevent low image density which occurs at the beginning of the use of a process cartridge and fog image which occurs after it is used for some time, in an image forming device having two or more processing speeds. SOLUTION: From the number of sheets of prints stored in a storage means 30, the amount of the use of the process cartridge corresponding to the processing speed is judged. In the case the number of sheets of the prints is small, the voltage of a primary bias which is supplied from a high-voltage unit 100 to a charge roller 2 is corrected according to the processing speed. Thus, the surface potential of a photoreceptive drum is changed. Further, by changing the surface potential of the photoreceptive drum gradually according to the amount of the use, variations in print width and line width are prevented. |
