| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus which forms a high-quality image free from image unevenness and does not cause failure such as squeaking of a blade by setting AC bias applied to a charging device to a proper region in a short period of time. SOLUTION: Initial AC bias is defined as Vpp[0], and Vpp[n]=Vpp[n-1]+ΔVpp is set. When Vpp[n] is equal to or under Vpp[MAX], charging bias obtained by superposing Vdc[M] on Vpp[n] is applied to a charging roller 2, and a DC current component Idc[n] at this point is detected. A difference (ΔIdc) between Idc[n] and the previous DC current component Idc[n-1] is calculated. When ΔIdc≤a, Vpp[n]-ΔVpp=Vpp[n-1] is decided for Vpp[A]. Whereas, when a<ΔIdc≤b, Vpp[n]-1/2ΔVpp is decided for Vpp[A]. COPYRIGHT: (C)2010,JPO&INPIT
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