| 摘要 |
<P>PROBLEM TO BE SOLVED: To easily prevent transfer failures caused by fluctuation in the resistance of a transfer roller, and to prevent increase in the output of a bias power supply. <P>SOLUTION: A toner image formed by an electrophotographic process is carried on a photoreceptor drum 11, a transfer roller 12 is brought into contact with the photoreceptor drum and a transfer nip part, and a transfer bias current is supplied to the transfer roller to transfer the toner image onto a transfer material sent to the transfer nip part. The transfer roller comprises a conductive shaft core 12a and an ionic conductive material 12b, disposed on the outer peripheral face of the conductive shaft core. A power feed roller 13 is connected to a transfer bias power supply 14 via a changing-over switch 15, and the conductive shaft core 12a is connected to the transfer bias power supply via a feed line 15a and a changing-over switch. A control device 17 controls, for example, a changing-over switch according to the temperature and humidity so as to selectively connect the transfer bias power supply to the power feed roller or the feed line. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
