| 摘要 |
PROBLEM TO BE SOLVED: To prevent formed toner on an image carrier from reaching a contact electrifying means as it is without being transferred to a transfer material in case of malfunction due to a transfer-material jam, with the result that electrification irregularity and electrification performance decrease occur. SOLUTION: A transfer-material detection sensor 75 is provided downstream in the direction of the rotation of a photoreceptor 1 and in the transfer nip part of the photoreceptor 1. In the case a controller 80 judges based on a signal inputted from the transfer-material detection sensor 75 that at the time of image formation the transfer material P has not been carried to the transfer nip part due to the occurrence of a jam, it exerts control so that a magnetic brush 3 is separated from the surface of the photoreceptor 1. This prevents untransferred toner from getting mixed in the magnetic brush 3, and hence preventing electrification irregularity and electrification-performance decrease which are caused by mixture of the untransferred toner. |
