Technical Field

The present invention relates to a computer- implemented method for inkjet printing and related equipment.

Background Art

Today, in the ceramic sector, but not only (think e.g. of printing on glass, wood, fabric or metal), the use of digital inkjet printers is widespread.

This type of printer comprises a supporting surface of a manufactured article to be decorated, which is movable along a direction of forward movement, and one or more print heads formed by a plurality of nozzles, which emit controlled jets of micro-drops of ink, taken from a tank or a cartridge.

The print heads are controlled by an electronic processor which gives a succession of printing commands to the various nozzles, depending on the image to be obtained and on the relevant position between the heads and the surface to be printed, by activating or leaving the nozzles inactive.

This printing method and its related equipment do, however, have some drawbacks.

In fact, it frequently happens that the manufactured article to be decorated is misaligned with respect to the direction of forward movement and with respect to the arrangement of the nozzles.

In other words, the median axis of the manufactured article to be decorated may be inclined with respect to the median axis of the related printer, and consequently the image obtained by means of the ink dispensed by the nozzles would be angularly offset with respect to the exposed surface of the manufactured article to be decorated.

The problem of aligning the image to be printed with the exposed surface of the manufactured article to be decorated is therefore deeply felt.

In order to overcome this drawback, various solutions have been devised over time, briefly described below.

A first solution is to use a centering device of the mechanical type, which involves the use of a mechanical element positioned upstream the printer and which is able to physically interact with the manufactured article to be decorated to rotate and/or shift it so that it is aligned with the printer itself. This solution has the drawback that the mechanical element may damage the manufactured article to be decorated, e.g. by rubbing against the edges of the same.

A second solution of known type involves the use of movable print heads, i.e. mounted on a support which can be displaced or rotated depending on the position of the exposed surface. This solution also has its drawbacks, since the movement operations of the heads are generally slow and do not ensure the required accuracy.

A third solution known at present consists in processing different versions of the same image to be printed and in choosing, each time, the one which best suits the inclination of the arriving exposed surface. This solution, however, requires the use of a computer with a very large memory and, in any case, allows the use of a limited number of images.

Description of the Invention

The main aim of the present invention is to devise a method and a piece of equipment for inkjet printing which allows the image to be printed to be conveniently and easily adapted to the manufactured article to be decorated regardless of the orientation thereof.

Within this aim, one object of the present invention is to enable the alignment of the image to be printed to the related exposed surface to be decorated with lower timings than those characterizing the solutions of known type, so as to obtain higher printing frequencies with respect to these solutions.

Another object of the present invention is to avoid damaging the manufactured article to be decorated during the alignment operations with respect to the image to be printed thereon.

Yet another object is to allow the image to be printed to be aligned to the related exposed surface to be decorated by means of a piece of equipment which requires the use of less sophisticated and expensive components than those of known type. Another object of the present invention is to devise a computer- implemented method for inkjet printing and the related equipment which allow the aforementioned drawbacks of the prior art to be overcome within the scope of a simple, rational, easy and effective to use as well as affordable solution.

The objects mentioned above are achieved by the present computer- implemented method for inkjet printing according to claim 1.

The objects mentioned above are also achieved by the present equipment for inkjet printing according to claim 13.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a method and equipment for inkjet printing, illustrated by way of an indicative, yet non-limiting example, in the accompanying tables of drawings wherein: Figure 1 is a schematic plan representation from above of a piece of equipment according to the invention;

Figure 2 is a schematic representation of the equipment in Figure 1 in the implementation of the phases of a method according to the invention for the decoration of a manufactured article which is aligned with respect to the printing equipment;

Figure 3 is a schematic representation of the equipment in Figure 1 in the implementation of the phases of a method according to the invention for the decoration of a manufactured article which is inclined with respect to the printing equipment.

Embodiments of the Invention

With particular reference to such figures, reference numeral 1 globally indicates a piece of equipment for inkjet printing.

The equipment 1 comprises a basic frame, not shown in detail in the figures, at least one supporting surface 2 of at least one manufactured article to be decorated Ml having an exposed surface Ma, wherein the supporting surface 2 is associated with the basic frame and is movable along a direction of forward movement 3. The equipment 1 then comprises a printing device 4 comprising a plurality of print heads 5, each provided with a plurality of nozzles, not visible in detail in the figures, for the dispensing of ink.

Suitably, the heads 5 are arranged on top of the supporting surface 2 in such a way that the related nozzles face the exposed surface Ma to be decorated during the passage of the manufactured article to be decorated Ml along the direction of forward movement 3.

More particularly, the equipment 1 comprises a plurality of groups 6 of heads 5, wherein each of such groups 6 comprises at least one row of heads 5 substantially (i.e., except for machining tolerances) aligned with each other along a same line of action 7. The lines of action 7 are parallel to each other and are arranged transversely with respect to the direction of forward movement 3. Advantageously, the heads 5 of each group 6 are arranged so as to be able to cover the entire supporting surface 2, transversely to the direction of forward movement 3.

In the particular embodiment shown in the figures, each group 6 comprises multiple rows of heads 5, the respective lines of action 7 of which are parallel to each other. The heads 5 of each row are staggered with respect to the heads of the adjacent row and belonging to the same group 6.

According to the invention, the equipment 1 comprises a plurality of dedicated processing and control units 8, each of which is operatively connected to at least one relevant print head 5 and is configured to control the dispensing of ink through the related nozzles.

The dedicated processing and control units 8 are mutually separate and independent.

The heads 5 controlled by each dedicated processing and control unit 8 are arranged in succession with respect to each other along the direction of forward movement 3.

Preferably, each dedicated processing and control unit 8 is operatively connected to a group 6 of heads 5 to control the dispensing of ink through the related nozzles. Therefore, the groups 6 of heads 5 controlled by each dedicated processing and control unit 8 are arranged in succession to each other along the direction of forward movement 3.

According to the invention, the equipment 1 comprises at least one main processing and control unit 9 operatively connected to the dedicated processing and control units 8 and configured to receive at input a final image F to be applied onto the exposed surface Ma, to decompose the final image F into a plurality of decorative portions P and to send at output, to the dedicated processing and control units 8, a related decorative portion P. The set of decorative portions P obtained through the decomposition performed by the main processing and control unit 9 then defines the final image F to be applied on the exposed surface Ma.

In the embodiment shown in the figures, the main processing and control unit 9 is separate from the dedicated processing and control units 8, although it cannot be ruled out that it may coincide with one of them.

The dedicated processing and control units 8 are programmed to control the related print heads 5 so as to reproduce the related decorative portions P on the exposed surface Ma. It follows, therefore, that the heads 5 controlled by each dedicated processing and control unit 8 are adapted to decorate only partly the exposed surface Ma, thereby covering a part of it with the related decorative portion P.

Advantageously, the equipment 1 comprises detection means, not shown in the figures, of the angle of inclination a of the exposed surface Ma to be decorated with respect to a preset reference position.

In the case of a manufactured article to be decorated Ml shaped substantially like a parallelogram and provided with a median axis, the preset reference position corresponds to that wherein such median axis is substantially aligned with a reference line 10, e.g. corresponding to the median axis of the groups 6 of heads 5 parallel to the direction of forward movement 3.

Preferably, to identify the angle of inclination a, the detection means detects the inclination between a reference side of the exposed surface Ma, e.g. the front forward side, and the reference line 10. Advantageously, the dedicated processing and control units 8 are configured to rotate the related decorative portions P by an angle equal to the detected angle of inclination a, so that each decorative portion P is angularly aligned with the exposed surface Ma.

In other words, the main processing and control unit 9 receives the final image F in digital format and in a predefined reference position, decomposes the image thus received, and sends the relevant decorative portions P to the corresponding dedicated processing and control units 8. The dedicated processing and control units 8 then receive the decorative portions P in digital format and oriented in a manner consistent with the reference position of the final image F and, then, each rotate the relevant decorative portion P by an angle equal to the angle of inclination a.

In more detail, the rotation of each of the decorative portions P operated by the related dedicated processing and control unit 8 is performed around a corresponding center of rotation C. The centers of rotation C of each decorative portion P are arranged aligned with each other.

More particularly, the centers of rotation C are aligned with each other along the reference line 10.

The terms “to rotate” or “rotation”, used herein with reference to the operations performed by the dedicated processing and control units 8 on the related decorative portions P, mean that the dedicated processing and control units 8 are configured to selectively identify and activate the nozzles of the related heads 5 by means of which the decorative portion P is, once applied, rotated by an angle equal to the angle of inclination a around the related center of rotation C. Therefore, it is not a physical rotation but a digital rotation of the individual decorative portions P.

The decorative portions P are therefore applied sequentially to each other on the exposed surface Ma during the displacement of the manufactured article to be decorated Ml along the direction of forward movement 3, so as to obtain, at the end of the passage below the last group 6 of heads 5, a decorated manufactured article M2 with the final image F aligned with its exposed surface Ma. Each decorative portion P is therefore rotated around the relevant center of rotation C by an angle equal to the detected angle of inclination a and applied onto a corresponding part of the exposed surface Ma during the passage of the manufactured article to be decorated Ml below the heads 5.

The operation of the equipment 1 in implementing the method according to the invention is as follows.

The method to which the present invention relates consists in providing at least one manufactured article to be decorated Ml, e.g. of the type of a slab made of a ceramic material, having an exposed surface Ma, and the movement thereof along the direction of forward movement 3 with respect to the printing device 4. The movement of the manufactured article to be decorated Ml along the direction of forward movement 3 is performed by means of the supporting surface 2.

According to the invention, a final image F in digital format is provided to be applied on the exposed surface Ma and the final image F is then decomposed into a plurality of decorative portions P.

More particularly, the final image F is sent in digital format to the main processing and control unit 9, which is configured to perform the decomposition thereof into a predefined number of decorative portions P.

Preferably, a phase of acquisition of the dimensions of the exposed surface Ma is performed before providing the final image F, and the final image F is selected in such a way that its dimensions correspond to those of the exposed surface Ma.

Advantageously, the decomposition of the final image F is performed parallel to the direction of forward movement 3.

In more detail, the decorative portions P have the same extension with respect to each other along a direction transverse to the direction of forward movement 3. Each decorative portion P is then sent, in digital format, to the dedicated processing and control units 8.

Appropriately, the sending of the decorative portions P to the dedicated processing and control units 8 is managed by the main processing and control unit 9.

The main processing and control unit 9 receives, therefore, at input the final image F in digital format and sends at output, again in digital format, the decorative portions P to the related dedicated processing and control units 8.

Preferably, the main processing and control unit 9 decomposes the final image F into a number of decorative portions P equal to the number of dedicated processing and control units 8. It cannot, however, be ruled out that the number of decorative portions P may be less than the number of dedicated processing and control units 8.

Advantageously, a phase of detection of the angle of inclination a of the exposed surface Ma is performed with respect to a preset reference position.

As discussed above, the reference position of the exposed surface Ma corresponds to the position that the exposed surface Ma should have in order to receive the final image F, obtained by means of ink dispensing, without the need to perform any alignment operation between them. In other words, the preset reference position corresponds to the position in which the exposed surface Ma is substantially aligned, e.g. with a median axis thereof, to the printing device 4, that is, to a predefined reference line 10.

The reference line 10 is appropriately oriented parallel to the direction of forward movement 3.

Advantageously, subsequent to the sending of the decorative portions P to the related dedicated processing and control units 8, at least one phase of rotation is performed of each of the decorative portions P by an angle equal to the detected angle of inclination a so that each decorative portion P is angularly aligned with the exposed surface Ma.

More particularly, the rotation of each of the decorative portions P is performed around a related center of rotation C, wherein the centers of rotation C of each of the decorative portions P are aligned with each other along the reference line 10.

Finally, each of the decorative portions P is applied to the exposed surface Ma by means of the print heads 5 controlled by the dedicated processing and control units 8 so as to obtain a decorated manufactured article M2 with the final image F.

Since the groups 6 of heads 5 connected to each dedicated processing and control unit 8 are arranged in succession with respect to each other along the direction of forward movement 3, it follows that the decorative portions P are applied in sequence onto the exposed surface Ma by the relevant groups 6 of heads 5, whereby the final image F is composed as the manufactured article to be decorated Ml passes below the heads themselves along the direction of forward movement 3.

It has, in practice, been ascertained that the described invention achieves the intended objects and in particular the fact is emphasized that the method and the equipment to which the present invention relates, through the decomposition of the final image to be applied on the manufactured article to be decorated, allow obtaining a precise and accurate decoration even on large surfaces, without the need to use particularly sophisticated computers and regardless of the orientation of the manufactured article itself.

More specifically, the use of a plurality of dedicated processing and control units, each of which is configured to manage an individual decorative portion to be applied on the exposed surface, makes the decoration and rotational operations of the portion itself easier since the size of the file to be managed is considerably smaller than that of the final image as a whole.

In this way, it is possible to perform a digital rotation of the individual decorative portions to be applied on the exposed surface of the manufactured article to be decorated using computers commonly available on the market and without the need for any physical interaction with the manufactured article itself.