| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent transfer voids at the leading edge of transfer material when performing transfer by a contact transfer device using a transfer belt, while display quality is improved by preventing transfer memory from occurring because of the electrification of a photoreceptor in a reverse polarity caused by a high current from the transfer device to the photoreceptor. <P>SOLUTION: If the transfer material is sheet paper P when multiply transferring a toner image to the transfer material on the transfer belt 11 in a quadruple tandem color copying machine, transfer bias is applied to conductive rollers 18a and 18d by constant voltage power sources 37a to 37d, whereby excellent transfer is attained regardless of the variation of a printing rate. Meanwhile, if the transfer material is an OHP sheet P1, the transfer bias is applied to the conductive rollers 18a to 18d by constant current power sources 38a to 38d, whereby the high current is prevented from being generated to the photoreceptor drums 12a to 12d even when the transfer bias is applied before the leading edge of the OHP sheet P1 reaches a nip part, and the occurrence of the transfer memory is prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT |
