| 摘要 |
PURPOSE:To form a stable image by extending an image carrier and a transfer means outside the image range where a transfer material is passed, insulating the extention part of the image carrier and the image range, and making current fed to the image carrier extention part constant by impressing transfer bias. CONSTITUTION:The lengths of the image carrier 1 and the transfer roll 2 in the axial direction are made longer by L than the width of the transfer material, and the passing range 1a'' of the transfer material of an aluminum substrate 1a constituting the image carrier and image carrier extention part 1a' are electrically insulated by an insulating flange 1d. Furthermore, the current Ia fed to the extention part 1a' of the image carrier by transfer bias of power source 3 is detected by a current detection circuit 4. In the substrate extension part 1a', since the current Ia is varied only by humidity, regardless of existence of the transfer material or the size, the current Ia is detected by the detection circuit 4, its signal fed to the power source 3, and desired electric field is obtained by controlling the bias output of the power source 3 responding to the time of low humidity and high humidity so that the current Ia is a fixed value I1. |
