10A of the duct 10 in the desired position, tangent to the inclined wall 2E of the lower part 2D of the tank, could also have a different shape from that described above and comprise for example a tubular element tangent to the inclined wall 2E and rigidly constrained to said wall 2E in the position in which said end portion 10A is to be positioned, in which to insert the end portion.

The tank also comprises therein usual sensors 16 FIG. 2B) adapted to detect the level of the ink in the tank; these sensors comprise for example three bar-type sensors 16A-C, one (16C) for detecting a low ink level (for example equal to 25% of the tank volume), one (16B) for detecting the optimal ink level, and one (16A) for detecting a high level (for example equal to 85% of the tank volume). As usual for the person skilled in the art, the sensors 16 also include a sensor 16D adapted to supply a reference value.

The tank also comprises a usual ventilation duct 18 (FIG. 4) which is connected to the upper part of the tank and, in particular, to the tank lid 14, as discussed below.

The tank also comprises, as usual for the person skilled in the art, a duct 17 for recirculating the ink coming from the printhead of a continuous inkjet printer (CIJ).

Preferably the tank has a portion 17D (FIG. 4A) extending inside the tank and comprises a small lower opening 17A for supplying the recirculated ink into the tank. Preferably a guide element 17B, for example a sheet inclined towards the wall of the tank and towards the bottom of the tank, is provided below the opening 17A, which is adapted to guide the ink up to an inner side wall 2J of the upper portion 2C of the tank, at the upper edge thereof. Since the ink which is recirculated may contain a significant quantity of air in the form of bubbles or foam, the blade-shaped guide element 17B also has the function of separating the air from the returning ink. To this end, the free edge 17C of the sheet 17B of the guide element is provided at a distance D13 from the inner face of the wall 2J of the tank of one or more millimeters. Thanks to the guide element 17B, the ink which initially enters the tank vertically through the duct 17D is deflected laterally against the inner wall 2J of the tank, so as to create an ink film which flows along the inner wall 2J of the tank. In this way the recirculated ink flow which can have a high flow rate or a pulsating development is turned into a film that flows slowly towards the surface of the ink present in the tank.

To this end, preferably, the tank 2 is sized in such a way as to be able to position the guide element 17B in the tank at a significant distance D14 (FIG. 4) from the maximum level M for filling the tank with the ink, which allows the recirculated ink film to flow along a large surface of the inner wall 2J of the tank exposed to the air and which is not covered by the ink, so that the air bubbles and/or the foam present in the recirculated ink are eliminated and at the same time the recirculated ink comes into contact with the ink present in the tank smoothly avoiding splattering or splashing.

For example, as described above, the tank optimal filling level is provided at a distance D20 (FIG. 4) from the bottom 2F of the tank, this distance D20 between 40% and 70% of the tank overall inner height D16, so that the tank includes a wall portion 2J of the tank which is not occupied by the ink and along which the recirculated liquid can flow. This wall portion 2J has a height D15 (FIG. 4) which is between 30% and 60% of the overall height D16 of the tank, more preferably between 40% and 50% of the overall height D16 of the tank. Consequently, also the guide element 17B is positioned at a distance D14 from the tank optimal filling level M, and this distance D14 is between 30% and 60% of the overall height D16 of the tank, more preferably between 40% and 50% of the overall height D16 of the tank.

It should be noted that the duct 17, as usual for the person skilled in the art, can be used to also supply into the tank the ink and/or the components thereof which do not come from the printhead, but for example from the module 7, adapted to feed the tank 2 with the ink and/or ink components.

The tank comprises a top lid 14 adapted to close the tank itself. Preferably, the lid 14 comprises connecting means 14A, B for removably fixing it to the tank (2); for example screws 14A (FIG. 2) adapted to fix it to the upper edge 2L (FIG. 2C) of the tank, in seats 14B provided at said edge of the tank.

Advantageously, at least the duct 9 for the ink outlet from the tank 2, and the duct 10 for the ink and/or the components thereof inlet in the tank 2 are connected to the lid by means of dedicated connecting means 20A, 20B (FIG. 2) in one piece and/or associated with the lid; preferably, also the ventilation duct 18 and/or the duct 17 for the recirculating ink inlet are connected to the lid by means of dedicated connecting means 20D, 20C in one piece and/or associated with the lid; even more preferably the level sensors 16 are also connected to the lid by means of dedicated connecting means 20E in one piece and/or associated with the lid.

The connecting means 20A-D each comprise, for example: a first connecting element 21A-D that faces the inside of the tank, adapted to receive and sealingly connect one end of said ducts 9, 10, 17, 18 (only some of these first connecting elements can be seen in the Figures), an intermediate tubular element 22A-D adapted to connect the first connecting element 21A-D and, therefore, also the respective ducts 9, 10, 17, 18, to second connecting elements 23A-D provided outside the lid and the tank and adapted to connect the tank to the ducts 3A, 6A, 8A of the ink recirculating system that, as described above, are provided for the ink outlet from the tank 2, for the ink and/or the components thereof inlet into the tank and for the recirculated ink inlet into the tank, respectively.

Preferably, the connecting means 20E of the level sensors also comprises: a plurality of first elements 21E (FIG. 4) which face the inside of the tank, and are adapted to receive and sealingly connect one end of the level sensors 16, an intermediate element 22E (FIG. 4) for connecting the sensors 16 to a plurality of second connecting elements 23E provided outside the lid, for connecting the sensors to a control unit (not shown) of the printer.

Thanks to this particular conformation of the lid, in which, preferably, all the ducts and/or connections of the tank are grouped in the lid 14 of the tank, the assembly and/or maintenance of the tank are extremely simplified and speeded up. In fact, the tank 2 together with its lid 14