Selective ink-jet printing device
First Claim
1. Selective ink jet printing device, in which printing is carried out by inducing the selective emission of particles of an electrically conductive liquid ink through a nozzle from an insulating container (19), the ink being kept under such a pressure such as to form a concave meniscus (42) in the nozzle (36), and the printing of a dot being carried out by a voltage pulse between a first electrode (23) which is in contact with the ink in the container and a second electrode (37) which is disposed outside of nozzle, so as to create excitation of the meniscus and an electric current in the ink in the nozzle which cause the expulsion of a first spray constituted by a plurality of ink particles, said voltage pulse also generating a pressure wave in the ink, the nozzle (36) and container (19) being of such a shape and size as to reflect the pressure wave in such a manner as to cause, within a predetermined time, the expulsion of a second spray constituted by ink particles.
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Accused Products
Abstract
The device comprises a printing head (15) constituted by an insulating container (19) with a capillary nozzle (36). The electrically conductive ink is kept under circulation in the container via a feed tube (26, 23) and a return tube (27, 24) leading to a suction pump, in order to allow the formation of a convex meniscus at the exit aperture of the nozzle (36) and eliminate any vapor bubbles. A pulse generator creates a voltage of a predetermined value and duration between an electrode (37) external to the nozzle and an electrode (23) in contact with the ink, in order to create a state of excitation of the meniscus and partial vaporization of a layer of ink, such as to expel a plurality of ink particles. The head is mounted on a carriage movable transversely to the paper, which advances at each stroke reversal of the head.
37 Citations
37 Claims
- 1. Selective ink jet printing device, in which printing is carried out by inducing the selective emission of particles of an electrically conductive liquid ink through a nozzle from an insulating container (19), the ink being kept under such a pressure such as to form a concave meniscus (42) in the nozzle (36), and the printing of a dot being carried out by a voltage pulse between a first electrode (23) which is in contact with the ink in the container and a second electrode (37) which is disposed outside of nozzle, so as to create excitation of the meniscus and an electric current in the ink in the nozzle which cause the expulsion of a first spray constituted by a plurality of ink particles, said voltage pulse also generating a pressure wave in the ink, the nozzle (36) and container (19) being of such a shape and size as to reflect the pressure wave in such a manner as to cause, within a predetermined time, the expulsion of a second spray constituted by ink particles.
- 4. Selective ink jet dot printing device, in which printing of a dot is carried out by selectively inducing an emission of particles of an electrically conductive liquid ink through a nozzle from an ink container made of insulating material, said ink normally filling said nozzle and forming a concave meniscus in the nozzle, said nozzle having an exit diameter of between 20 to 100 micron and a length of at least six times said diameter, a first electrode in contact with the ink in the container and a second electrode disposed on the outer surface of said container adjacent the nozzle, and electrical means selectively operable to excite said electrodes to create a resistive electric current in the ink in the nozzle as to create an instantaneous vaporization of a portion of said ink adjacent said exit, thus causing the expulsion of ink particles from said nozzle.
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6. Selective ink-jet dot printing device, in which printing of a dot is carried out by selectively inducing an emission of particles of an electrically conductive liquid ink through a nozzle from an insulting container, wherein the ink is kept under such a pressure such as to form a concave meniscus in the nozzle, said nozzle having an exit diameter of between 20 to 100 micron and a length of at least six times said diameter and the printing of a dot is carried out by a voltage pulse between a first electrode which is in contact with the ink in the container and a second electrode which is disposed outside the nozzle, so as to create excitation of the meniscus and an electric current in the ink in the nozzle such as to create an instantaneous vaporization of a part of ink adjacent said exit, which cause the expulsion of ink particles.
- 7. An ink jet dot printing device, in which printing of a dot is carried out by selectively inducing an emission of particles of an electrically conducting liquid ink through a nozzel, comprising an ink container made of insulating material, said nozzel being substantially conical and being provided on said container, said nozzel having a smallest diameter of between 20 to 100 micron and a length of at least six times said diameter, said ink being kept under such a pressure in said container as to form a concave meniscus on the exit of said nozzel, a first electrode in contact with the ink in said container, a second electrode on the outer surface of said container adjacent the exit of said nozzle, and a pulse generator selectively generating a voltage pulse between said electrodes to create an excitation of the meniscus and an electric current in the ink of said nozzle, the density of said current in the portion of said nozzle having said smallest diameter being such as to create an instantaneous vaporization of part of said ink to cause the expulsion of ink particles from the nozzle.
- 19. An ink jet dot printing device, in which printing of a dot is carried out by selectively inducing an emission of particles of an electrically conductive liquid ink through a nozzle from an ink container made of insulating material, said ink normally filling said nozzle and forming a concave meniscus in the nozzle, said nozzle being substantially conical and having a smallest diameter of between 20 to 100 micron and a length of at least six times said diameter, and first electrode in contact with ink in said container and a second electrode disposed on the outer surface of said container adjacent said nozzle, electrical means selectively operable to excite said electrodes as to create a resistive electric current in the ink in said nozzle, the density of which in the portion of said nozzle having said smallest diameter being such as to create an instantaneous vaporization of part of said ink, thus causing the expulsion of ink particles, said container having a wall perpendicular to said nozzle and having a distance from the entrance of said nozzle as to enhance the expulsing action of said vaporization.
- 35. An ink jet dot printing device, in which printing of a dot is carried out by selectively inducing an emission of particles of an electrically conductive liquid ink through a nozzle from an ink container made of insulating material, said ink normally filling said nozzle and having a specific resistance of between 20 and 300 ohms.cm, a surface tension of between 40 and 65 dynes/cm and a viscosity of between 1 and 1.4 centistokes, a first electrode in contact with the ink in said container, a second electrode disposed on the other surface of said container adjacent said nozzle, and a pulse generator selectively operable to generate a voltage pulse to excite said electrodes as to create a resistive electric current in the ink in said nozzle, said nozzle having a substantially conical shape with a smallest diameter of between 20 and 100 micron, said pulse generator being so dimensioned as to generate such a pulse with such a peak as to create an instantaneous vaporization of part of said ink in correspondence of said smallest diameter, thus causing the expulsion of ink particles.
Specification