Printing apparatus with improved ion focus

摘要

A printing unit includes a current limited, low capacitance corona wire located 1-5 mm away from biased conductive plates which form a slit that allows ions to pass therethrough onto a receptor surface. The conductive plates are used to control the flow of ions through the slit and opposing wedges are positioned on each conductive plate in order to focus additional ions to the center of the slit. At inside edges of the slit there are additional fringe fields that aid in pumping ions out of the slit.