Modulation structure for fluid jet assisted ion projection printing apparatus

Claim 1

A fluid jet assisted electrographic marking apparatus for placing electrostatic charges upon a charge receptor in an image-wise pattern, said apparatus being characterized by including housing means including an upstream, ion generation region and a downstream, ion modulation region, means for supplying a transport fluid to said housing, means for delivering the transport fluid to said housing at a location upstream of said ion generation region for entraining ions in the fluid path and moving them with fluid, a channel in said housing for receiving the transport fluid from said ion generation region and for directing the transport fluid and entrained ions through said ion modulation region, said channel defining a bent path and being of a width such that laminar flow of the transport fluid will prevail therethrough, and ion modulation means, located at said ion modulation region, including an array of electrically conductive modulating electrodes located on one side of said channel, at a position downstream of its bend, and disposed upon a substantially planar substrate, said electrodes including a first portion extending in the plane of said substrate and a second portion departing from the plane of said substrate by an angle of less than 45°, a conductive member on the side of said channel opposite to said modulating electrodes, a source of modulating potential, switch means for selectively connecting said source of modulating potential to each of said modulating electrodes, and a source of reference potenital connected to said conductive member, whereby each of said modulating electrodes controls the passage of a beam of ions out of said bent path channel, when its respective switch is energized.