Corona wire cleaning by mechanical vibration of the wire

Abstract

Non-magnetic toner in a fluidized bed is charged by at least one corona wire extending through the bed, the non-magnetic toner surrounding the wire in the fluidized bed. In order to prevent build up of insulating particles on the corona wire (which leads to a change in electric field gradient and eventually adversely impacts on the uniformity of the image applied to the substrate with the toner) is substantially precluded by vibrating the wire to shake toner particles off the wire. Vibration is accomplished at spaced points in time, such as by utilizing a rod having an irregular (e.g. substantially sinusoidal shaped) surface and by reciprocating the rod to cause the irregular surface to engage the wire and cause a quick rise and release thereof, so that the wire goes through a wide series of frequencies when vibrating. The rod may be reciprocated by a pneumatic cylinder, and may be of stainless steel having a substantially circular cross section with a diameter between about 0.02-0.04 inches. The at least one corona wire is connectable to a source of electric current and extends between and is supported by first and second corona wire support structures. A number of high strength fiberglass rods may extend between the support structures for positioning shielding, and a spring may be associated with a support structure for engaging and mounting the wire at or adjacent one end of the wire. The support structure may also include a guide (such as the spaced sets of ball bearings) for precisely guiding the rod during reciprocation.