Abstract: An ink jet print head cleaning and maintenance system has a purge chamber for applying a vacuum to a nozzle orifice surface. A specialized baffle diverts ink entering the purge chamber away a vent port through which the vacuum is drawn. An elongated wipe engages and wipes the orifice surface and is preferably moved at an extremely slow rate across the surface to enhance the wiping operation. An air knife directs a narrow stream of air across a portion of the nozzle orifice surface with air from the air stream being scanned across the surface for cleaning purposes. A specialized drip edge is positioned beneath the orifice surface for directing drops of ink away from the ink jet print head, the drops of ink being generated during the cleaning procedures. A mechanically simple cam mechanism coupled to a rotatable drum of the printer may be used to shift the maintenance system against the nozzle orifice surface for cleaning purposes.

Abstract: An ink jet print head face cleaner provides a controlled air passageway through an enclosure formed against the print face. Air is directed through an inlet into a cavity in a body. The body has a face with an opening into the cavity. This face is sealingly placeable against the print face. The cavity has a limited size so that air is directed without interruption through the cavity past the ink jet apertures, and out an outlet. The cleaner body is coupled resiliently to a platform to allow positioning of the body and print faces flush with each other. A vacuum source is preferably attached to the outlet to create a subatmospheric pressure in the cavity to further seal the two faces together. A collection chamber and removable drawer are positioned below the outlet to facilitate disposing of removed ink.

Abstract: A viscoelastic and ink-immiscible fluid is used to form a membrane over the ink orifice of a drop-on-demand, pressure pulse ink jet head. The membrane lies in a plane perpendicular to the direction of emission of ink drops, and provides a barrier between the ink orifice and the external atmosphere. Evaporation of the ink, or entry of contaminants including air into the ink, is thus inhibited. The elimination of evaporative clogging then permits the use of a smaller orifice. Wetting of the exterior surface of the ink jet head by the flow of ink through the ink orifice is also inhibited, thus making possible the production of more uniform ink drops that will emerge in a constant direction. The elastic property of the membrane permits the passage of an ink drop therethrough, followed by the closing up of the membrane.

Abstract: An air-assisted drop-on-demand ink jet head 10 has a single compartment ink chamber 14 and is designed for operation over a wide range of ink drop repetition rates, including extremely high repetition rates, such as twenty kilohertz. The components included in the ink jet head have natural resonance frequencies which are greater than the desired maximum drop generation frequency of the ink jet head. In addition, the natural frequency of each of the components of the ink jet head are sufficiently different from one another to prevent intercoupling. Ink is supplied to the ink chamber 14 via a supply inlet passageway 38 which has a cross-sectional area which is sized large enough to allow the supply of ink to the ink chamber. Yet, this area is small enough so that the natural frequencies of ink in the ink inlet do not significantly alter drop generating pressure pulses in the ink chamber 14.

Abstract: An air assisted drop-on-demand ink jet head 10 has an ink chamber with an ink drop-forming orifice outlet 23 from which ink drops are generated in response to pressure waves caused by a piezoelectric crystal 56. The ink drops are carried by air outwardly through an external orifice 24 and toward printing medium. The internal orifice outlet 23 is centered in a projecting structure 48 which extends toward the external orifice 24. In one form, the projection 48 is of a frustoconical or mesa-like shape. Air flowing past the top of the projection prevents ink from wetting anything but the top of the projection, resulting in highly uniform ink drop formation with a single uniform dot being produced on the printing medium in response to each pressure wave.