Scavengeless two component development with an electroded development roll

摘要

A two-component development unit for an electrophotographic printer includes a rotatable donor roll having a plurality of longitudinal electrodes along its circumference. A magnetic structure within the donor roll permits two-component developer to be advanced to a development zone. Adjacent electrodes on the donor roll are AC biased in opposite phases so as create a powder cloud of toner from the developer in the development zone. The magnetic structure is arranged to provide pole effects substantially immediately downstream and upstream of the development zone in the direction of motion of the donor roll.