Methods and apparatus for cleaning paper in a high speed electrostatic

Abstract

In an electrostatic high speed line printer, a pair of lightly wetted cylindrical rollers are sequentially arranged upstream of the print station to engage the paper surface to be printed. The roller surfaces are wetted with a very thin film of non-staining viscous film such as isopar, and driven at roughly the same speed as the paper causing the paper surface to be very slightly wetted, thereby tending to attract debris particles from the surface of the paper to the roller and also tending to cause other debris particles to be adhered to the paper surface at least until after they have passed through the print head. A dancer roller is positioned on the opposite side of the paper from the wet rollers, between the wetted rollers, to provide approximately 30.degree. of wrap across each wetted roller. The foregoing is disclosed in combination with an electrostatic high speed line printer wherein an image (or data) modulated stream of air ions is attracted toward an electrode positioned behind and supporting the print receiving paper. The modulated ion stream passes through a fine mist or cloud of substantially uncharged ink particles which are charged in a pattern corresponding to the modulated pattern of the ion stream and attracted to the paper surface to cause printing in accordance with such patterns. Very high speed operation, up to and exceeding 10,000 lines of print per minute, are shown.