| 摘要 |
PROBLEM TO BE SOLVED: To detect fogging toner level at high precision and perform correction control such as developing bias correction according to the detected result in an image forming apparatus. SOLUTION: A density sensor 21 is installed on a more downstream side in the transporting direction of recording paper than a transfer roller 15 and this density sensor is provided with a light emitting part 21a and a light receiving part 21b installed in positions facing each other with a paper transporting path on which the recording paper is passed between them. In a fogging detection mode detecting the fogging level indicating the degree of fogging caused by a fogging phenomenon, OHP sheet is supplied instead of the recording paper, developing bias is controlled in a state where exposure is not performed by electrifying a surface of a photoreceptor drum 12 and fogging toner is supplied from developing roller 2 at every prescribed interval to the photoreceptor drum. Then, the transfer bias is controlled, fogging toner is transferred to one surface of the OHP sheet and the fogging level is determined according to the toner density detected by the density sensor. COPYRIGHT: (C)2006,JPO&NCIPI |
