Ing C. Olivetti C., S.p.a.

Enrico Manini

Renatol Conta

Alessandro Scardovi

Riccardo Brescia

Giandomenico Dagna

Giorgio Tadini

Edoardo Balbo

The head is provided for a conductive ink in contact with an electrode (34) and comprises a container (14) having a capillary nozzle (18, 53) and a counterelectrode (54) set into the nozzle that predetermined thickness of ink is in the front part (53) of the nozzle between the meniscus (52) and the inner part of the nozzle wherein a vaporizing current flows between the electrode and the counterelectrode, thereby to expel the said thickness of ink. For that purpose, the container is closed by an insulating plate (30, 31) on which the counterelectrode (54) is disposed, the counterelectrode in turn being covered by a dielectric layer (56). The nozzle is formed by means of a single hole through the plate, the counterelectrode may be of the same thickness as the said thickness of ink, so that the front part of the nozzle is all through the counterelectrode. The dielectric layer may be a first layer covered by a second layer with a hole in the first layer which is larger in diameter than the nozzle, thereby to create a reserve of ink for the frequent dots. For a multi-nozzle head, the nozzles are produced by grooving a portion of the container and then closing over the grooves by an insulating plate bearing the electrodes and the counterelectrodes which are spaced along the axes of the nozzles.

Ink jet print head

The head is provided for a conductive ink (16) and comprises a container (14) having a capillary nozzle (18) where the ink is in contact with a pair of electrodes facing each other across the nozzle, in such a way as to be covered by a predetermined depth of ink between the electrodes and the meniscus (52) at the front end of the nozzle. Printing is effected by vaporization of a portion of ink in a section of the nozzle between the electrodes, which expels the said depth of ink. The container is closed by an insulating plate (30) over which extends a metal strip (37) of smaller width than the diameter of the nozzle. The nozzle is formed by means of a single hole through the plate and the strip, whereby the strip is separated into two electrodes. The metal strip may be disposed between the plate and a front dielectric layer 43. The latter may also be covered by a second insulating layer having a front part of the nozzle therethrough, while the first dielectric layer may have a hole which is larger in diameter than the nozzle so as to create a reserve of ink for the frequent dots. For a multi-nozzle head, the nozzles are produced through an insulating plate over which extend the strips for a plurality of pairs of electrodes.

A droplet of ink 11 is expelled from a nozzle in a wall, so as to strike a printing medium, by suddenly moving the wall towards the ink 11 with which it is in contact. This movement is effected by energizing a piezoelectric sleeve. The ink droplet is expelled by virtue of the inertia of the ink resisting the movement of the wall and creating pressure. Practical embodiments are described in which the wall containing the nozzle is formed by the tapered end of a capillary tube.

Ink jet printing method and device

The ink jet dot printer comprises a head mounted on a carriage movable along a platen supporting the paper and is formed by a plurality of tubes and piezoelectric transducer for ejecting the ink, which are supported by two parallel plates spaced from one another, between which a polymerizable resin is cast to form a single block. The tubes are aligned in a single row F--F' in a direction inclined with respect to the printing line, in such manner that the distance between the extreme tubes measured perpendicularly to the printing line is equal to the maximum height of the characters. On the outside of the front plate supporting the tubes there is fixed a thin plate bearing a row of nozzles, each of which is aligned with the corresponding ejector tube. The expulsion of the drops of ink is obtained by means of the compression exerted on the tubes by the piezoelectric transducers activated in parallel by electric pulses generated by an energizing circuit under the control of a driving logic circuit by means of which it is possible to vary the slope of the printed characters and obtain bidirectional printing at high speed.

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Camandona, Italy

Enrico Manini