Converging axis dual-nozzled print head and printer fitted therewith

1. Twin-nozzle print head for a continuous inkjet deflection printer, the print head comprising:

an ink drop generator assembly having two inkjet ejection nozzles, each of the inkjet ejection nozzles having an ejection axis,

and arranged along the ejection axis:

charge electrodes,

first and second deflection electrodes deflecting charged drops, these deflection electrodes each having relative to said inkjet ejection nozzles an upstream part and a downstream part, an active surface of each deflection electrode being a surface of said electrode lying opposite a succession of drops,

a single ink drop recovery gutter for both said inkjet ejection nozzles,

wherein the ejection axes of said inkjet ejection nozzles converge at a point located on an axis of a single inlet orifice of the single recovery gutter, the point being in the vicinity of this inlet orifice or upstream of this recovery gutter.

2. Twin-nozzle print head as in claim 1 , having a plane of symmetry which is a plane perpendicular to a plane defined by the converging ejection axes of the inkjet ejection nozzles and containing a bisector of the angle formed between said converging ejection axes of the inkjet ejection nozzles.

3. Twin-nozzle print head as in claim 2 , wherein the first deflection electrode deflecting charged drops is a first electrode common to the drops derived from the inkjet ejection nozzles, this common deflection electrode for charged drops being located between the second deflection electrodes for charged drops.

4. Twin-nozzle print head as in claim 1 , where the first deflection electrode deflecting charged drops is a first electrode common to the drops derived from the inkjet ejection nozzles, this common deflection electrode for charged drops being located between the second deflection electrodes for charged drops.

5. Twin-nozzle print head as in claim 1 , wherein the active surface of the first deflection electrode deflecting drops from a jet has a first concave longitudinal curvature whose local radius of longitudinal curvature is located in the plane formed by the converging ejection axes of the inkjet ejection nozzles, in that the active surface of the second deflection electrode deflecting drops from said same jet has a first convex longitudinal curvature, and in that the first deflection electrode deflecting drops from said jet, in its downstream part, has a recess having a contour.

6. Twin-nozzle print as in claim 5 , wherein said contour has a most upstream point located in the vicinity of the intersection before said recess of said first deflection electrode deflecting said jet, with the ejection axis of said inkjet ejection nozzle of said jet.

7. Twin-nozzle print head as in claim 5 , that wherein the recess has symmetry relative to the plane defined by the converging ejection axes of the inkjet ejection nozzles.

8. Twin-nozzle print head as in claim 5 , wherein the width of recess ranges between two and 10 times the diameter of the charged drops.

9. Twin-nozzle print head as in claim 5 , wherein the recess is in the form of an oblong slit of which one opening leads to a part which is the most downstream of first electrode.

10. Twin-nozzle print head as in claim 5 , wherein the space between the active surfaces of deflection electrodes deflecting a jet derived from one of the inkjet ejection nozzles is substantially constant from upstream to downstream of the electrodes and lies between 4 and 20 times the diameter of the charged drops.

11. Twin-nozzle print head as in claim 5 , wherein the second deflection electrode deflecting an inkjet has a groove along an axis contained in the plane defined by the converging ejection axes of the inkjet ejection nozzles.

12. Twin-nozzle print head as in claim 11 , wherein a bottom of groove is joined to the active surface of said second electrode via a surface curved transversely along curve radii of greater value than the radius of the charged drops.

13. Twin-nozzle print head as in claim 5 , wherein tongues of said first deflection electrode deflecting a jet formed either side of the recess and second deflection electrode deflecting the same jet are curved transversely along curve radii of greater value than the radius of the charged drops.

14. Twin-nozzle print head as in claim 5 , wherein the inkjet ejection nozzles have different diameters.

15. Twin-nozzle print head as in claim 5 , wherein orifice of the recovery gutter is of oblong shape.

16. Twin-nozzle print head as in claim 1 , wherein one most downstream edge of a first deflection electrode is more downstream than a surface that is most downstream of recovery gutter.

17. Printer equipped with a twin-nozzle print head according to any of the preceding claims.

18. Twin-nozzle print head for a continuous inkjet deflection printer, said print head comprising:

an ink drop generator assembly having two inkjet ejection nozzles, each of the inkjet ejection nozzles having an ejection axis, these ejection axes converging at a point located on an axis of a single inlet orifice of a single ink drop recovery getter, the point being in the vicinity of this inlet orifice or upstream of this recovery gutter,

charge electrodes arranged along the ejection axis of the inkjet ejection nozzles,

a plurality of deflection electrodes each having relative to inkjet ejection nozzles an upstream part and a downstream part, and each having an active surface which is a surface said deflection electrode lying opposite a succession of drops, the plurality of deflection electrodes comprising a first deflection electrode and second deflection electrodes,

the first deflection electrode arranged along the ejection axis of the inkjet ejection nozzles and deflecting charged drops, said first deflection electrode being common to the drops derived from the inkjet ejection nozzles, having a recess having a contour in the downstream part, and the active surface of the first deflection electrode having a first concave longitudinal curvature whose local radius of longitudinal curvature is located in the plane formed by the converging ejection axes of inkjet ejection nozzles, and

the second deflection electrodes arranged along the ejection axis of the inkjet ejection nozzles and deflecting charged drops, the active surface of which having a first convex longitudinal curvature, the common deflection electrode for charged drops being located between the second deflection electrodes for charged drops.

19. Twin-nozzle print head as in claim 18 , wherein the recess is in the form of an oblong slit of which one opening leads to a part which is the most downstream of first electrode.

20. Twin-nozzle print head as in claim 19 , wherein the recess has symmetry relative to the plane defined by the converging ejection axes of the inkjet ejection nozzles.