EP3490805B1 - Device and method for aligning printheads - Google Patents

Description

The invention is directed to a device and a method for adjusting print heads relative to one another, which are equipped for printing with several nozzles in a nozzle plate and for production and / or assembly purposes with at least one round hole and at least one elongated hole in this nozzle plate, in particular before and during installation in a common printhead mounting plate.

In order to print different colors and / or to increase the printing speed, several print heads are often operated at the same time. These are then usually attached to a common holder, in particular screwed on. It is important that the individual nozzles of different print heads are precisely aligned in a common grid, or that their spacings and orientations are set exactly to one another.

In order to adjust or set several such print heads with respect to one another, micrometer screws are used in the prior art, with the aid of which the individual print heads can be displaced relative to one another until a desired alignment precision is achieved. This requires shifts in two directions which are oriented at right angles to one another, for example to the left and right on the one hand and back and forth on the other, so that such a setting requires a large number of iteration steps and is therefore very tedious.

That is why an attempt has already been made to improve the software for controlling the print heads instead of a lengthy adjustment. In particular, there is the possibility of compensating for an offset in the feed direction of the printing device in that certain nozzles or entire print heads shoot earlier / later. If there is an offset across the Is to be compensated for the feed direction, there is at least the possibility of controlling the nozzle rows with correspondingly shifted and / or interchanged signals in the event of an offset of the order of magnitude of an integer grid spacing. Finding the right compensation here, however, is also extremely time-consuming. In addition, tilting or inclinations can hardly be compensated for in this way, or only with an unjustifiable effort.

DE 20 2012 001234 U1 represents the relevant state of the art.

The disadvantages of the described prior art result in the problem initiating the invention of finding a way of how print heads of a printing device can be adjusted relative to one another with little effort.

This problem is solved by an assembly jig for several printheads, in particular with at least one exactly matching counterpart to at least one round hole and at least one elongated hole in the nozzle plate in question being provided for each printhead, so that by plugging the printheads onto the assembly jig that a pair of round hole and elongated hole counterparts engages in the round and elongated hole of the nozzle plates in question, the nozzles of all print heads are aligned with one another in the desired manner.

The invention is defined by an apparatus according to claim 1 and a method according to claim 11.

The invention is based on the following consideration:

The round and / or elongated holes used by the invention for centering are not the side mounting holes in the area of the narrow end faces of the print heads through which the mounting screws are inserted and screwed, but rather recesses in the nozzle plate itself, i.e. in the lowest lying plate of the printhead. Normally, these recesses do not penetrate the housing of the printhead mounted above the nozzle plate and are therefore not suitable for screwing in fastening screws. Because thus the mounting holes of a printhead are not used by the assembly jig, they remain free for screwing in the fastening screws.

On the other hand, the adjustment holes according to the invention are not one of the nozzles themselves, because they are extremely filigree objects which should not come into direct contact with external objects.

Rather, in the production of print heads, their individual components are manufactured separately and then have to be placed on top of one another as precisely as possible and finally glued and / or welded. In order for this assembly to be successful, each part is often made with two holes, preferably with a round hole and an elongated hole - including the nozzle plate. These two holes, in particular a round hole, is / are like (each) an oversized nozzle that is perfectly spaced from the other, normal-sized nozzles. This nozzle plate is then appropriately applied to the chamber via at least one round hole and / or via at least one elongated hole and glued to it, and this unit then onto the piezo elements, etc. This assembly is then at some point on the body and the actual outer shell including the receptacle for the assembly to a retaining plate or the like. Glued. One, two or more adjustment pins can then be inserted into this receptacle. However, since the dimensional tolerance between the relevant components increases with each step of assembly, there is no longer any exact alignment between these adjustment pins and the actual nozzles - the relative tolerances can be in the range of one or more tenths of a millimeter. The print heads must therefore be aligned manually and / or inaccuracies must be compensated for using software.

However, since the nozzle plate with the nozzle spacings is manufactured together with the round hole and / or the elongated hole in a single part, there is at most a dimensional tolerance in the micrometer range between the round hole and the elongated hole and the individual nozzles. This is about the factor 100 more accurate than the relative tolerances between the adjustment pins on the one hand and the nozzle openings on the other. Due to the assembly of a print head, the pressure chamber behind the nozzle plate can be shifted, and the piezo elements, housing parts, adjustment pins can also have an offset, which, however, can be neglected in the context of the present invention for the adjustment accuracy of the nozzles.

Because in the context of the invention, an assembly jig is used which represents one or preferably several "negative impressions" of the nozzle plate (s), and preferably has two exact counterparts for its production round hole and / or elongated hole, which are exactly in the relevant round or elongated hole fit into it. These counterparts are two pins - one for matching engagement in the round hole and the other for matching engagement in the elongated hole. The pin for the round hole preferably has a circular cross section, while the pin for the elongated hole has an elongated cross section. Since the round and elongated holes are completely sufficient for an adjustment, the "negative impression" of the nozzle plate according to the invention does not have to have any counterparts for the individual nozzles.

Since the nozzle plates of the individual print heads are accessible through the holding plate of the printing device in order to have free access to the printing substrate for printing, it is possible to place the assembly jig according to the invention directly under the holding plate. The print heads can then be placed on the holding plate in such a way that their round and elongated holes provided on the underside of the nozzle plate have direct contact with the counterpart pins in the assembly jig and can be plugged together with them.

This means that all nozzle plates are perfectly aligned with one another; It does not matter whether the remaining components of the print heads (housing, piezo elements, bracket, adjustment pins, etc.) are also optimally aligned; it is much more important that every nozzle plate is absolutely true to size, ie, through precise positioning of the nozzle plate by means of its round and elongated hole, the nozzle openings provided in the relevant nozzle plate are also aligned with the same precision. In this state, the print heads can then be screwed tightly to the print head holding plate, and a printing device with a corresponding multiple or large number of optimally aligned print heads is obtained with minimal effort.

The advantages that can be achieved with the invention are:

Simple and time-saving alignment of all print heads of a printing device with maximum precision.

Large printhead arrays with a large number of individual printheads can be assembled with the same nozzle precision as a single printhead.

At the customer's facility, replacing a print head is easy and problem-free without lengthy adjustments.

As a purely mechanical solution, the assembly jig according to the invention is less prone to failure.

An assembly jig according to the invention can be used both when replacing individual or multiple print heads; on the other hand, entire holding plates with printheads applied to them can also be exchanged, since each printhead holding plate equipped using the same assembly jig has identical nozzle arrangements and software compensation is therefore not required.

The invention further provides that the assembly jig is designed for application on the underside of a holding plate for several print heads. By plane-parallel contact takes place a first adjustment between the printhead holding plate and the assembly jig.

For this purpose, the assembly template according to the invention has an upper-side contact surface facing the underside of the holding plate. This contact surface can be substantially flat, while elevations or depressions differing therefrom can be provided in the area of the assembly points of the individual print heads.

To accommodate the nozzle plates of a plurality of print heads, a print head holding plate according to the invention has continuous recesses, whereby the actual printing then takes place.

It is within the scope of the invention that the assembly jig has marked or highlighted, in particular raised areas on its contact surface facing the holding plate, preferably for centering on the holding plate, in particular for centering engagement in the continuous recesses of the holding plate for receiving the nozzle plates of several print heads.

On the other hand, the assembly jig can have one or more depressions, preferably one or more elongated depressions for receiving one or more rows of nozzles of a print head, on its contact surface facing the holding plate, in particular in the area of the marked or highlighted or raised areas.

Since the counterparts provided on the assembly jig for at least one round hole and / or at least one elongated hole, preferably the pins, must engage with the respective round and / or elongated holes of the nozzle plates of the print heads, they should be on the contact surface facing the holding plate Assembly jig be arranged, in particular in the area of the marked or highlighted or raised areas.

Further advantages of the invention result from the fact that the counterparts provided on the assembly jig for at least one round hole and / or at least one elongated hole, preferably the pins, on the contact surface of the assembly jig facing the holding plate in the area of opposite ends of one or more elongated depressions are arranged for receiving one or more rows of nozzles of a print head. There are two adjustment holes relatively far apart and can therefore bring about optimal centering.

The invention can be developed in such a way that in each case a pair of counterparts provided on the assembly jig for at least one round hole and / or at least one elongated hole, preferably the pins, on the contact surface of the assembly jig facing the holding plate, for example - but preferably not exactly - in a Is arranged in alignment with an elongated recess for receiving one or more rows of nozzles of a print head. At that point there is enough space in a nozzle plate to accommodate the round and / or elongated holes without affecting the printing mechanism.

Another design specification states that a pair of pendants provided on the assembly template for at least one round hole and / or at least one elongated hole, preferably the pins, on the contact surface of the assembly template facing the retaining plate, opposite the longitudinal center axis of the relevant elongated recess for receiving a or a plurality of rows of nozzles of a printhead is laterally offset, preferably by half the width of the printhead plate or less. As a result, in addition to such a round and / or elongated hole, there is space on the print head for further elements, for example extensions arranged on the rear of the print head, for example for preferably automatic handling of the print head during its installation.

The invention recommends that several pairs of counterparts provided on the assembly jig are provided for at least one round hole and / or at least one elongated hole, preferably the pins, on the contact surface of the assembly jig facing the holding plate, in each case opposite the longitudinal center axis of the one assigned to each pair, elongated recess for receiving one or more rows of nozzles of a print head laterally offset, in particular laterally offset in the same direction for all pairs. This ensures that all print heads are installed with exactly the same orientation, so that an optimal printing result is achieved.

The assembly jig according to the invention can have one or more means for fixing to the holding plate, for example clamping elements, so that undesired displacement is not possible during the assembly of the print heads on the print head holding plate.

The assembly jig should consist of a metal plate, in particular a plate of a noble metal or non-ferrous metal or a stainless steel, or a corrosion-free metal alloy, so that it cannot warp or otherwise deform. In particular, for this reason the assembly jig should also have a sufficient minimum thickness, for example 3 mm or more, preferably 5 mm or more.

In order to achieve an optimal alignment between different print heads for the subsequent printing result, the raised counterparts provided on the assembly jig should be in one piece with the at least one round hole and / or at least one elongated hole, preferably the pins on the contact surface of the assembly jig facing the retaining plate Plate-shaped base body of the assembly jig can be produced, that is, not by inserting or screwing pins into holes provided for this purpose, but by making the raised counterparts together with the plate itself from an originally single part. As a manufacturing and / or post-processing methods are particularly suitable for this purpose: milling and / or eroding.

In the context of a particular embodiment of the invention, at least one raised counterpart to at least one round hole and / or to at least one elongated hole, preferably at least one pin, provided on the assembly template can be detachably held in the assembly template, in particular in a retaining recess thereof. Such alignment pins can be individually pulled out of the plate-shaped part of the assembly jig backwards after the printheads have been assembled with the printhead holding plate, so that the plate-shaped part of the assembly jig can finally be easily removed.

So that such a releasable alignment pin is precisely fixed in a holding recess of the assembly jig, the invention recommends that at least one pin provided on the assembly jig is held in a through cutout of the assembly jig in the form of a transition or press fit.

At least one pin provided on the assembly jig should be longer than the thickness of the plate of the assembly jig, in particular in such a way that the pin protrudes both on the front side facing the holding plate and on the rear side of the assembly jig facing away from the holding plate and protrudes backwards out of the plate of the assembly jig can be pulled out. Thus, when the assembly jig is attached to a holding plate, such a pin is accessible from its rear side at any time and can be grasped at the area of the pin protruding there, for example with a pair of pliers, and pulled out.

The invention also provides that at least one pin provided on the assembly jig has a preferably all-round collar, in particular in that area of the pin which, when the pin is inserted into the holding plate, lies immediately behind the rear of the assembly jig facing away from the assembly jig. If such an alignment pin is so far from the The back of the assembly jig is inserted into its holding recess until this collar rests against the back of the assembly jig, the adjustment pin in question protrudes by a standardized amount over the front of the assembly jig.

So that such an adjusting pin can be easily inserted into a holding recess of the assembly jig, the invention recommends that at least one pin provided on the assembly jig has a cross-sectionally beveled or rounded edge on its end face protruding beyond the front of the assembly jig facing the holding plate. In this way, the pin finds a kind of loose fit at the first moment of attachment, which only gradually changes into a transition or press fit in the course of insertion and then ensures a precise fit of the adjusting pin in its holding recess.

A method for adjusting print heads relative to one another, which each comprise a nozzle plate, each with a plurality of nozzles for printing and with at least one round hole each and / or with at least one elongated hole each for production and / or assembly purposes, is characterized according to the invention in that an assembly jig for several printheads, on which for each printhead at least one exactly matching counterpart, preferably in the form of a pin, to at least one round hole and / or to at least one elongated hole in the nozzle plate in question, is provided, several printheads are attached in such a way that a pair of round hole and / or elongated hole counterparts engages in the round and / or elongated hole of the nozzle plate in question, so that the nozzles of all print heads are aligned with one another in the desired manner, and that then the print heads adjusted in this way relative to one another on the The printhead mounting plate is screwed on or otherwise fixed before the assembly jig is removed.

The assembly jig thus remains in contact with the printheads until they are all fixed immovably on the printhead holding plate.

The invention provides that the assembly jig is placed under the printhead holding plate before the printheads are attached to the assembly jig. This makes it possible to place the print heads on the assembly jig through the recesses in the print head holding plate. In this case, a region of a print head that protrudes to the side, in particular at the front, remains above the print head holding plate and can be screwed to it without an assembly jig arranged in between being an obstacle.

It can also be provided that the assembly jig is fixed to the underside of the printhead holding plate before the printheads are attached to the assembly jig. The assembly jig on the underside can be removed at any time; however, it can be set temporarily for the assembly of the print heads so that no relative displacements are to be feared.

Since the printheads are plugged onto the mounting template through recesses in the printhead holding plate, the nozzle plates on the underside can come into direct engagement with the mounting plate without having to make changes to the printhead holding plate or to a printhead.

The printheads attached to the assembly jig can be attached to the printhead holding plate, for example, by screwing them on, preferably by means of screws screwed into the printhead holding plate from above, which are in particular screwed laterally next to a continuous recess in the holding plate for receiving the nozzle plate of the respective printhead where there is direct contact between a printhead and the printhead support plate.

Finally, it corresponds to the teaching of the invention that the assembly jig is only removed from the printhead holding plate after the printheads have been attached to the printhead holding plate, in particular screwed, because only after the intimate, immovable connection of a printhead to the printhead holding plate the assembly jig according to the invention fulfills its task. However, it can be used again for repair purposes in the event of a temporary dismantling of printheads, in order to restore the unit of printheads and printhead holding plate at any time with a reproducible accuracy.

Fig. 1

eine Druckeinrichtung mit mehreren, an einer gemeinsamen Halteplatte befestigten Druckköpfen in einer perspektivischen Ansicht schräg von oben;

Fig. 2

die Halteplatte der Druckeinrichtung aus Fig. 1 nach Demontage der Druckköpfe, in einer der Fig. 1 entsprechenden Perspektive;

Fig. 3

eine erfindungsgemäße Montagelehre für den Zusammenbau der Druckköpfe mit der Halteplatte, ebenfalls in einer perspektivischen Ansicht;

Fig. 4

einen Vertikalschnitt durch eine Anordnung mit mehreren an einer Halteplatte fixierten Druckköpfen bei gleichzeitiger Ausrichtung mittels einer erfindungsgemäßen Montagelehre;

Fig. 5

eine Anordnung mit mehreren an einer Halteplatte fixierten Druckköpfen bei gleichzeitiger Ausrichtung mittels einer erfindungsgemäßen Montagelehre in einer transparenten, perspektivischen Darstellung;

Fig. 6

einen Ausschnitt aus der Fig. 5 in einer größeren Darstellung; sowie

Fig. 7

eine der Fig. 4 entsprechende Darstellung einer abgewandelten Ausführungsform der Erfindung.

Further features, details, advantages and effects based on the invention emerge from the following description of a preferred embodiment of the invention and with reference to the drawing. Here shows:

Fig. 1

a printing device with a plurality of print heads fastened to a common holding plate in a perspective view obliquely from above;

Fig. 2

the holding plate of the printing device Fig. 1 after dismantling the printheads, in one of the Fig. 1 appropriate perspective;

Fig. 3

an assembly jig according to the invention for assembling the print heads with the holding plate, also in a perspective view;

Fig. 4

a vertical section through an arrangement with several print heads fixed on a holding plate with simultaneous alignment by means of an assembly jig according to the invention;

Fig. 5

an arrangement with several printheads fixed on a holding plate with simultaneous alignment by means of a assembly jig according to the invention in a transparent, perspective illustration;

Fig. 6

an excerpt from the Fig. 5 in a larger representation; as

Fig. 7

one of the Fig. 4 corresponding representation of a modified embodiment of the invention.

The drawing shows a device 1 for adjusting print heads 2 relative to one another which, for printing, are each equipped with a plurality of nozzles 3 which are arranged in a nozzle plate 4 on the underside.

When assembling a printing machine, there is often a need to fix several such print heads 2 together on a print head holding plate 5 as part of a printing device. For example, it is customary in multicolor printing machines to provide one or even several print heads 2 for each color. It can be the case that the same color is printed on different print heads 2, but with a different color intensity. In addition, by using several print heads for inks of the same color and color intensity, the printing speed can be increased, ideally duplicated.

It is of crucial importance that the individual print heads 2 are positioned relative to one another in such a way that their nozzles 3 lie in a common, predetermined grid.

One recognizes in Fig. 2 the printhead holding plate 5 before being fitted with printheads 2. At the location of each printhead 2 there is an elongated opening 6 which corresponds approximately to the base area of a nozzle plate 4 or is slightly larger than that. In the area of the narrow end faces 7 of an elongated opening 6 there is one stepped one in each case Area 8 where the thickness of the holding plate 5 is reduced. A print head 2 with laterally protruding tabs 9 is to be anchored there, in particular screwed tight. The tabs 9 are offset backwards or upwards relative to the nozzle plate 4, so that they can each be inserted into a stepped area 8 and fastened therein, while the nozzle plate 4 is then lower, namely approximately in alignment with the underside 10 of the holding plate 5.

Alignment pins 11 can be provided in the area of the side tabs 9, on the one hand, and fastening bores 12 for screwing a print head 2 to the holding plate 5, on the other hand adequate centering of the print heads 2 with respect to the holding plate 5; rather, readjustment is required. In order to make this possible, the alignment pins 11 - if present - must not have any bores with a fit in the stepped areas 8, but there must be clearance between them to enable manual alignment.

How to do the Fig. 4 and 5 can be seen, in the nozzle plate 4 of a print head 2 shown, in addition to the actual nozzles 3, there is also a round hole 13 and an elongated hole 14. Usually, however, the elongated hole 14 is hardly larger than the round hole 13. If the round hole 13 has a diameter of 1, 5 mm, the elongated hole 14 can also have a width of 1.5 mm and a length of about 2 mm. These two holes 13, 14 are also present in other parts of the print head 2, but not necessarily in its housing 15, in any case not penetrating that; they are only intended to allow these parts to be fitted with a precise fit, but do not serve to anchor the print head 2 to the print head holding plate 5. Since the round hole 13 and the elongated hole 14 together with the nozzles 3 are located directly in the one-piece nozzle plate 4 these openings 3, 13, 14 are generally aligned with one another with an accuracy of micrometers due to the manufacturing process.

An assembly jig 16 according to the invention for a plurality of print heads 2 makes use of this.

This assembly jig 16 has the shape of a plate, with at least one exactly matching counterpart to at least one round hole 13 and to at least one elongated hole 14 in the relevant nozzle plate 4 being provided for each print head 2. These counterparts have the shape of pins 17, 18, of which one pin 17 has a circular cross-section, precisely fitting the round hole 12, and the other pin 18 can have an elongated - or also a round - cross-section, of which at least the width is precisely fitting the width of the elongated hole 14, so that this pin 18 can be inserted into the elongated hole 14 - at least in one dimension with an accurate fit.

This assembly jig 16 can be applied to the underside 10 of the holding plate 5 and - preferably by fitting pins and openings or in some other way - aligned so that the pins 17, 18 are each located in the area of an opening 6 in the holding plate 5. Slightly raised areas on the surface of the assembly jig 16 facing the holding plate 5, which can each engage in an opening 6 of the holding plate 5, can also be used for this purpose.

Now the print heads 2 are inserted into the openings 6 of the holding plate 5 in such a way that each pin 17 of the assembly jig 16 engages in a round hole 13 in the nozzle plate 4 of a print head 2 and one pin 18 each in an elongated hole 14 of the same. Once this has been done for all print heads 2, they are exactly aligned with one another. If the lateral tabs 9 of the print heads 2 are screwed tightly to the stepped areas 8 by means of fastening screws 19, all print heads 2 are exactly connected to the holding plate 5, and additional adjustment is no longer necessary.

Of course, the print heads 2 can also be attached to the mounting jig 16 one after the other and screwed to the holding plate 5 at the same time, if it is ensured that the mounting jig 16 cannot move relative to the holding plate 5 during the entire assembly process, so that the mounting jig 16 will move during the assembly The installation of the last print head 2 relative to the holding plate 5 is still exactly at the same point as when the first print head 2 was inserted.

In Fig. 7 FIG. 13 is a slightly different embodiment of the invention in a view according to FIG Fig. 4 shown, so that by comparing these two figures, the peculiarity of the additional embodiment is immediately recognizable.

In contrast to the embodiment described above, in the embodiment according to Fig. 7 the engaging in the round or elongated hole 13, 14 pins 17, 18 of the assembly jig separated from the actual plate of the same and inserted into specially machined holes in the plate of the assembly jig 16, so that they are on the top of the print head 2 facing the The plate of the assembly jig 16 survive. The pins 17, 18 are received in these bores in the manner of a press fit or a transition fit and are therefore precisely aligned.

As can be seen, these pins 17, 18 also protrude from their receiving bores in the assembly jig 16 on the rear side facing away from the print head 2. After the printheads 2 have been assembled with the printhead holding plate 5, the pins 17, 18 on the rear side of the assembly jig 16 can therefore first be pulled out, and the assembly jig 16 can then be easily removed from the printhead holding plate 5. Furthermore, in Fig. 7 It can be seen that the pins 17, 18 have an all-round collar in their rear region facing away from the round or elongated hole 13, 14 may have, which limits the depth of insertion into the bores of the assembly jig 16.

If pins 17, 18 without such a collar are also used, they could also be inserted into the nozzle plate 4 of the relevant print head 2 before the assembly of a print head 2 with the print head holding plate 5, so that when the print head 2 is attached to the assembly jig 16 penetrate into their bores and thereby center the relevant print head 2.

List of reference symbols

1

contraption

2

Printhead

3

jet

4th

Nozzle plate

5

Printhead mounting plate

6th

opening

7th

Front side

8th

Graduated area

9

Tab

10

bottom

11

Adjustment pin

12th

Mounting hole

13th

Round hole

14th

Long hole

15th

casing

16

Assembly jig

17th

pen

18th

pen

19th

Fastening screws

Claims (15)

1. A device for adjusting printheads (2) relative to each other during the mounting thereof to a printhead retaining plate (5), wherein the printheads (2) each comprise a nozzle plate (4) having multiple nozzles (3) for printing, and having at least one round hole (13) and/or at least one elongated hole (14) in the nozzle plate for manufacturing and/or assembly purposes, and wherein the printhead retaining plate (5) comprises an elongated opening (6) at the site of each printhead (2), which corresponds to the base area of a nozzle plate (4) or is greater than that, such that the nozzle plate (4) has open access to the substrate to be imprinted through the elongeted opening (6), characterized by an assembly template (16) for multiple printheads (2) with a top-side contact surface that faces the bottom side (10) of the retaining plate (5), wherein for each printhead (2) at least one counterpart is provided, preferably in the form of a pin (17, 18), which fits exactly to at least one round hole (13) and/or to at least one elongated hole (14) in the corresponding nozzle plate (4), so that when the printheads (2) are inserted into the assembly template (16) in such a way that each pair of round hole counterparts and elongated hole counterparts (17, 18) engages with the round hole and/or elongated hole (13, 14) in the corresponding nozzle plate (4), the nozzles (3) of all printheads (2) are aligned with one another in the desired manner, wherein the assembly template (16) is detachable from the retaining plate (5) after screwing or fixing the printheads (2) to the retaining plate (5).
2. The device according to Claim 1, characterized in that the assembly template (16) is designed for application to the bottom side (10) of a retaining plate (5) for multiple printheads (2).
3. The device according to Claim 1 or 2, characterized in that the assembly template (16) on its contact surface facing the retaining plate (5)

   a) has marked or emphasized, in particular elevated, areas, preferably for centering engagement with the continuous recesses in the retaining plate (5), for accommodating the nozzle plates (4) of multiple printheads (2), and/or

   b) has one or more depressions, preferably one or more elongated depressions, for accommodating one or more rows of nozzles (3) of a printhead (2).
4. The device according to one of the preceding claims, characterized in that the counterparts to at least one round hole (13) and/or to at least one elongated hole (14), preferably the pins (17, 18), provided on the assembly template (16) are situated on the contact surface of the assembly template (16) facing the retaining plate (5), in particular in the area

   a) of the marked or emphasized or elevated areas, and/or

   b) in the area of oppositely situated ends of one or more elongated depressions for accommodating one or more rows of nozzles (3) of a printhead (2).
5. The device according to one of the preceding claims, characterized in that in each case a pair of counterparts, provided on the assembly template (16), to at least one round hole (13) and/or to at least one elongated hole (14), preferably the pins (17, 18), on the contact surface of the assembly template (16) facing the retaining plate (5)

   a) either is in approximate alignment with an elongated depression for accommodating one or more rows of nozzles (3) of a printhead (2),

   b) or is laterally offset with respect to the longitudinal center axis of the elongated depression in question for accommodating one or more rows of nozzles (3) of a printhead (2), preferably offset by one-half the width of the printhead plate or less.
6. The device according to one of the preceding claims, characterized in that multiple pairs of counterparts, provided on the assembly template (16), to at least one round hole (13) and/or to at least one elongated hole (14), preferably the pins (17, 18), on which the contact surface of the assembly template (16) facing the retaining plate (5) is provided, are each laterally offset with respect to the longitudinal center axis of the elongated depression, associated with each pair, for accommodating one or more rows of nozzles (3) of a printhead (2), in particular laterally offset in the same direction for all pairs.
7. The device according to one of the preceding claims, characterized in that the assembly template (16)

   a) has one or more means, for example clamping elements, for fixing to the retaining plate (5), and/or

   b) is made from a metal plate, in particular a plate made of a noble metal or nonferrous metal or stainless steel, or a corrosion-resistant metal alloy.
8. The device according to one of the preceding claims, characterized in that elevated counterparts, provided on the assembly template (16), to at least one round hole (13) and/or to at least one elongated hole (14), preferably the pins (17, 18)

   a) on the contact surface of the assembly template (16) facing the retaining plate (5) are manufactured in one piece with the plate-shaped base body of the assembly template (16), and/or

   b) are produced or machined on the contact surface of the assembly template (16) facing the retaining plate (5) by milling and/or eroding of a preferably plate-shaped base body of the assembly template (16).
9. The device according to one of the preceding claims, characterized in that at least one elevated counterpart to at least one round hole (13) and/or to at least one elongated hole (14), preferably at least one pin (17, 18), provided on the assembly template (16) is releasably retained in the assembly template (16).
10. The device according to Claim 9, characterized in that at least one pin (17, 18) provided on the assembly template (16)

    a) is held in a through hole opening in the assembly template (16) in the form of a transition fit or press fit, and/or

    b) is longer than the thickness of the plate of the assembly template (16), in particular in such a way that the pin (17, 18) protrudes at the front side facing the retaining plate (5), and also at the rear side of the assembly template (16) facing away from the retaining plate (5), and is removable from the plate of the assembly template (16) from the rear, and/or

    c) has a preferably continuously circumferential collar, in particular in the area of the pin (17, 18) that is situated directly behind the rear side of the assembly template (16) facing away from the retaining plate (5) when the pin (17, 18) is inserted into the retaining plate (5), and/or

    d) has a cross-sectionally beveled or rounded edge on its end-face side that protrudes beyond the front side of the assembly template (16) facing the retaining plate (5).
11. A method for adjusting printheads (2) relative to each other during the mounting thereof to a printhead retaining plate (5), wherein the printheads (2) each comprise a nozzle plate (4) having multiple nozzles (3) for printing, and having at least one round hole (13) and/or at least one elongated hole (14) in the nozzle plate for manufacturing and/or assembly purposes, and wherein the printhead retaining plate (5) comprises an elongated opening (6) at the site of each printhead (2), which corresponds to the base area of a nozzle plate (4) or is greater than that, such that the nozzle plate (4) has open access to the substrate to be imprinted through the elongeted opening (6), characterized in that several printheads (2) are inserted onto an assembly template (16) for several printheads (2) with a top-side contact surface that faces the bottom side (10) of the retaining plate (5), at which for each printhead (2) at least one counterpart is provided, preferably in the form of a pin (17, 18), that fits exactly into at least one round hole (13) and/or at least one elongated hole (14) in the corresponding nozzle plate (4), in such a way that each pair of round hole counterparts and/or elongated hole counterparts (17, 18) engages with the corresponding round holes and elongated hole (13, 14) in the nozzle plate (4), so that the nozzles (3) of all printheads (2) are aligned with one another in the desired manner, and the printheads (2) that are adjusted relative to one another in this way are then screwed onto the printhead retaining plate (5) or affixed in some other way before the assembly template (16) is removed.
12. The method according to Claim 11, characterized in that the assembly template (16) is placed beneath the printhead retaining plate (5) and/or is fixed to the bottom side of the printhead retaining plate (5) before the printheads (2) are inserted into the assembly template (16).
13. The method according to one of claims 11 or 12, characterized in that the printheads (2) are inserted into the assembly template (16) through recesses in the printhead retaining plate (5).
14. The method according to one of claims 11 to 13, characterized in that the printheads (2) inserted into the assembly template (16) are fastened to the printhead retaining plate (5) by screwing, for example, preferably screwed into the printhead retaining plate (5) from the top, in particular in each case screwed in from the side, next to a continuous recess in the retaining plate (5) for accommodating the nozzle plate (4) of the printhead in question (2).
15. The method according to one of claims 11 to 14, characterized in that the assembly template (16) is not removed from the printhead retaining plate (5) until the printheads (2) have been fastened, in particular screwed, to the printhead retaining plate (5).

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