Transfer roller with resistivity range

摘要

An electrographic machine 10 has a transfer station where a toner image is transferred to a receiver sheet 8. That sheet travels at a high speed of more than 15 inches per second and up to as high as 40 inches per second. A transfer roller has a metal core 212 and an elastomeric sleeve 214 with a resistivity selected to optimize transfer of toner at high speeds. The resistivity of the sleeve is selected to be high enough to support transfer of the toner but not so high as to cause the surface voltage to exceed the breakdown voltage of the dielectric material that includes the elastomeric sleeve, the receiver sheet, the toner and the photoreceptor.