Dot printer with electrically propelled ink

Claim 1

A print head, for a column-sequential or row-sequential dot matrix printer which prints dots by electrically propelling droplets of electrically conductive ink onto a record, comprising: a manifold defining an ink chamber; a plurality of closely spaced generally parallel ink tubes having their inner ends in communication with the ink chamber and their outer ends terminating in a linear array of ink orifices, each ink tube having a diameter large enough so that the tube may be filled with electrically conductive ink yet small enough to restrain the free flow of ink therefrom; a corresponding plurality of electrode pairs, each pair of electrodes having end portions extending into a respective one of the ink tubes at generally diametrically opposed positions adjacent the orifice end of the ink tube to provide a current path across the orifice through electrically conductive ink in the tube; and magnetic means for creating a uniform magnetic field across the orifice ends of all of the ink tubes, the direction of the magnetic field being generally perpendicular to both the current paths across the ink tubes and the axes of the tubes, the magnetic means constituting a single magnet having its opposite poles located immediately adjacent the orifice array in positions such that the magnetic field of the one magnet extends through all of the orifices.