| 摘要 |
PURPOSE:To accurately recognize the state of a transfer material and to always perform a stable excellent transfer regardless of environmental conditions and the kind of the transfer material by detecting a transient charging current in the thickness direction of the transfer material, on all transfer materials, just before transfer. CONSTITUTION:A humidity sensor 30 is disposed in the vicinity of an image carrier 3 and a pair of electrode rollers 32 and 33 detecting the transient charging current flowing in the thickness direction of the transfer material P are disposed between a first resist roller 5 and a second resist roller 6. Further, in a transfer part where a transfer drum 9 faces the image carrier 3, a conductive brush 21 applying a transfer bias is arranged inside the transfer drum 9. Then, a transfer electric field control quantity is determined by a first electric field control coefficient selected according to humidity information from the humidity sensor 30 and a second electric field control coefficient selected according to current information from a pair of the electrode rollers 32 and 33. Toner is transferred on the transfer material P in optimum conditions by transfer power supply output by a control quantity. |
