ES2540864T3 - System and method for orienting magnetic flakes or lamellae contained in an ink or varnish vehicle applied on a sheet-shaped or band-shaped substrate - Google Patents

Abstract

System for orienting magnetic scales contained in an ink or varnish vehicle applied on a sheet-shaped or strip-shaped substrate, whose system comprises a treatment unit (10 *) with at least one magnetic field induction device for orienting the magnetic scales contained in the ink or varnish vehicle applied on the substrate, whose treatment unit (10 *) is located along a path (P) of the substrate such that the substrate is brought into contact with the unit of treatment (10 *) or close proximity thereof and at least to said magnetic field induction device, wherein the system further comprises at least one drying or curing unit (60) disposed in the vicinity of the unit of treatment (10 *) to dry or cure the ink or varnish vehicle to fix the orientation of the magnetic scales contained therein while the substrate is still in contact with the treatment unit ( 10 *) or in close proximity thereof and at least to said magnetic field induction device before the substrate is removed from at least said magnetic field induction device, characterized in that at least said drying unit (60) or curing is a UV curing unit comprising LED elements that produce radiation in the UV range, whose LED elements are arranged in the form of a longitudinal bar that extends transversely to the substrate path.

Description

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DESCRIPTION

System and method for orienting magnetic flakes or lamellae contained in an ink or varnish vehicle applied on a sheet-shaped or band-shaped substrate

Technical field

This refers in general to a system and method for orienting magnetic flakes or lamellae contained in an ink or varnish vehicle applied on a substrate in the form of a sheet or sheet or in the form of a band. The present invention is especially applicable and usable in the context of the production of security documents, such as banknotes. The present invention also relates to a printing press containing such a system.

Background of the invention

A printing press comprising a cylindrical body for orienting magnetic scales is known as such in the art. Such printing press is for example described in International application No. WO 2005/000585 A1 filed in the name of the present applicant.

An embodiment of a printing press fed with sheets or sheets described in International Application No. WO 2005/000585 A1 is represented in fig. 1. This printing press is adapted to print sheets or sheets according to the screen printing process and comprises a feeding station 1 for feeding successive sheets to a group 2 of screen printing where the screen printing designs are applied on the sheets. In this example the printing group 2 comprises a printing cylinder 2a cooperating with two sieve cylinders 2b, 2c located in succession along the printing path of the sheets. Once treated in the printing group 2, the newly printed sheets are transported by means of a conveyor system 3 to a delivery station 4 comprising a plurality of delivery stacking units, three in this example. The conveyor system 3 is typically an endless chain conveyor system comprising a plurality of separate fixing or gripping bars (not shown in Fig. 1) that extends transversely to the direction of transport of the sheets, each bar comprising fixing tweezers to hold a leading edge of the sheets.

In the example illustrated in fig. 1, a treatment unit 10 * comprising a cylinder 10 carrying a plurality of magnetic field induction devices is located along the path of the sheets transported by the chain conveyor system 3. This cylinder 10 is designed to apply a magnetic field at selected positions of the sheets for the purpose of orienting the magnetic scales contained in the ink or varnish designs that have just been applied on the sheets in the printing group 2. A drying or curing unit 5 is provided with water below the cylinder 10 to dry, respectively cure, the ink / varnish applied on the sheets after the magnetic scales have been oriented, such unit 5 being typically an infrared drying unit or a UV curing unit depending on the type of ink or varnish used.

An improved cylinder configuration is the subject of International Application No. WO 2008/102303 A2 on behalf of the present applicant.

Other details relating to screen printing presses, including relevant details of the screen printing press illustrated in fig. 1, can be found in European patent applications No. EP 0 723 864 A1, EP 0 769 376 A1 and in International applications No. WO 97/29912 A1, WO 97/34767 A1, WO 03/093013 A2, WO 2004 / 096545 A2, WO 2005/095109 A1 and WO 2005/102699 A1.

Screen printing is adopted in particular in the context of the production of security documents, such as banknotes, to print optically variable designs on documents, including so-called iridescent designs and OVI® designs (OVI® is a brand registered commercial of SICPA Holding SA, Switzerland). Such designs are printed using inks or varnishes that contain pigments or special scales that produce optically variable effects.

The so-called "magnetic flakes or lamellae" are also known in the art, whose scales have the peculiarity that they can be oriented or aligned by a properly applied magnetic field. Although the term "magnetic scales" is used, it should be understood that this terminology designates scales that can be oriented using a magnetic field, including scales that are not necessarily magnetic per se but are capable of being oriented using a magnetic field. Such magnetic scales and the method for orienting such magnetic scales are described in particular in US Patent No. 4,838,648, in European Patent Application No. EP 0 686 675 A1, and in International Applications No. WO 02/073250 A2, WO 03/000801 A2, WO 2004/007095 A2, WO 2004/007096 A2, WO 2005/002866 A1.

The most convenient method for applying the above magnetic scales is by screen printing as described in the aforementioned International Application WO 2005/000585 A1. This is mainly due to the fact that the scales have a relatively large size that restricts the choice of printing processes available to apply inks or varnishes containing such scales. In particular, it must be ensured that the scales are not destroyed or damaged during the printing process, and screen printing is the most convenient printing process to achieve this objective. In addition, screen printing has the advantage

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from which relatively thick layers of ink or varnish can be applied. In addition, the inks or varnishes used in screen printing exhibit a relatively low viscosity that favors the proper orientation of the magnetic scales.

However, other printing processes could be considered to apply inks and varnishes containing magnetic scales. In European patent application EP 1 650 042 A1, it has been proposed, for example, to apply such magnetic scales in an engraving printing process ("intaglio"), whereby the engraving ink similar to a paste containing the scales is heated to reduce the viscosity of the ink and thus allow the scales to be more easily oriented. This can be done in a conventional engraving printing press, since the plate cylinder of such presses is commonly brought to an operating temperature of approximately 80 ° C during printing operations.

The orientation of the magnetic scales is carried out by applying a suitable magnetic field to the newly applied ink or varnish containing the magnetic scales. By proper shaping of the magnetic field field lines, as described for example in the aforementioned patent publications, the magnetic scales can be aligned in any desired design producing a corresponding optically variable effect that is very difficult, if not impossible. to fake

As already mentioned here before, a suitable solution for orienting the magnetic scales consists in bringing the sheets in contact with a rotating cylinder that carries a plurality of magnetic field induction devices.

With reference again to fig. 1, and as described in International Application No. WO 2005/000585 A1, the cylinder 10 could alternatively be located in the sheet transfer position 3a between the printing cylinder 2a and the conveyor system 3. Still in accordance with another embodiment considered in International Application No. WO 2005/000585 A1, the printing cylinder 2a itself could be designed as a cylinder carrying magnetic field induction devices.

In the embodiment illustrated in fig. 1, the cylinder 10 used to orient the magnetic scales advantageously cooperates with the unprinted side of the sheets, thereby preventing staining problems, the magnetic field being applied from the back side of the sheets through the newly printed designs of ink or varnish During the orientation of the magnetic scales, that is at the moment in which a sheet transported by the conveyor system 3 makes contact with the upper part of the circumference of the cylinder 10, the cylinder 10 is rotated at a circumferential speed corresponding to the speed of the transported sheets so that there is no relative displacement between the transported sheets and the circumference of the cylinder. As illustrated, the cylinder 10 is positioned in the path of the chain conveyor system 3 such that the sheets follow a curved path tangential to the outer circumference of the cylinder 10, thereby allowing part of the surface of the treated sheet be brought into contact with the outer circumference of the cylinder 10.

In the context of the production of banknotes, in particular, each printed sheet (or each successive part of a continuous band, in the case of band printing) carries a grouping of prints arranged in an array of rows and columns, whose prints they ultimately form individual securities after the final cutting of the sheet or band parts. The cylinder used to orient the magnetic scales is therefore specifically provided with as many magnetic field induction devices as there are prints on the sheet or strip parts.

As illustrated in fig. 1, the drying or curing of the ink or varnish vehicle is carried out downstream of the cylinder 10 by means of a suitable drying or curing unit 5, that is after the substrate has been removed or removed from the treatment unit 10 * in which the orientation of the magnetic scales is being carried out.

The tests have shown that the separation of the substrate from the treatment unit 10 * in which the orientation of the scales is carried out can cause undesired effects on the orientation resulting from the scales since such separation necessarily leads to a modification of the field magnetic applied to the substrate.

One solution to this problem may be to use electromagnets to act as the magnetic field induction devices and sequentially interrupt the applied magnetic field, row after row, before the substrate is separated from the treatment unit, but this is a solution. expensive (compared to the use of permanent magnets) and may not ultimately solve all problems since the deactivation of electromagnets can also affect the orientation of the scales contained in the ink or varnish vehicle applied on the substrate.

There is therefore a need for an improved solution that overcomes the aforementioned problem.

Summary of the invention

A general purpose of the invention is therefore to improve the known systems and processes.

More specifically one purpose of the present invention is to provide a solution that ensures that the separation of the substrate from the treatment unit in which the orientation of the magnetic scales contained in the vehicle of

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Ink or varnish is carried out to have an effect as small as possible on the resulting optical effect to be induced in the layer of ink or varnish applied on the substrate.

Still another purpose of the present invention is to provide a solution that can be suitably integrated into a practical system, especially in a printing press.

These purposes are achieved thanks to the solution defined in the claims.

A system as defined in claim 1 has therefore been provided, in particular a system for orienting magnetic scales contained in an ink or varnish vehicle applied on a sheet-shaped substrate.

or in the form of a band, whose system comprises a treatment unit with at least one magnetic field induction device to orient the magnetic scales contained in the ink or varnish vehicle applied on the substrate, whose treatment unit is located along of a substrate path such that the substrate is brought into contact with the treatment unit or close proximity thereof and at least to said magnetic field induction device. The system further comprises at least one drying or curing unit arranged in the vicinity of the treatment unit for drying or curing the ink or varnish vehicle to fix the orientation of the magnetic scales contained therein while the substrate is still in contact with the treatment unit or in close proximity thereof and at least said magnetic field induction device before the substrate is removed from at least said magnetic field induction device, in which at least one drying unit or Curing is a UV curing unit comprising LED elements that produce radiation in the UV range, whose LED elements are arranged in the form of a longitudinal bar that extends transversely to the substrate path.

A process as defined in claim 8 has also been provided, in particular a process for orienting magnetic scales contained in an ink or varnish vehicle applied on a sheet-shaped substrate.

or in the form of a band, whose process includes the following operations:

(to)

bringing the substrate into contact with or in close proximity to at least one magnetic field induction device to orient the magnetic scales contained in the ink or varnish vehicle applied on the substrate, and

(b)

 Dry or cure the ink or varnish vehicle to set the orientation of the magnetic scales contained therein,

operation (b) being performed while the substrate is still in contact or in close proximity to at least said magnetic field induction device before the substrate is removed from at least said magnetic field induction device, in which the Operation (b) includes the application of UV radiation to the substrate using LED elements that produce radiation in the UV range, whose LED elements are arranged in the form of a longitudinal bar that extends transversely to the substrate path.

Preferably, the treatment unit comprises a cylindrical body and at least said magnetic field induction device is disposed on an outer circumference of the cylindrical body. In this context, the substrate is advantageously brought into contact with the outer circumference of the cylindrical body or in close proximity thereof on a selected angular sector and at least said drying or curing unit is located close to the outer circumference of the cylindrical body in one end downstream of the selected angular sector.

In the context of the invention, the treatment unit may comprise a plurality of magnetic field induction devices distributed in a matrix-shaped arrangement to orient the magnetic scales contained in a plurality of ink or varnish designs applied on the substrate in a corresponding arrangement in matrix form. In the case of a cylindrical body as mentioned above, the plurality of magnetic field induction devices would be distributed over the outer circumference of the cylindrical body.

According to the invention, at least said drying or curing unit is a UV curing unit, that is to say a unit capable of applying UV radiation to the substrate, to induce polymerization of the ink or varnish vehicle.

The use of the previous system for the production of security documents, such as banknotes, and a printing press comprising such a system have also been claimed.

In advantageous embodiments of the invention they form the object of the dependent claims and are described below.

Brief description of the drawings

Other features and advantages of the present invention will appear more clearly upon reading the following description of embodiments of the invention that are presented only by way of non-restrictive examples and illustrated by the accompanying drawings in which:

Fig. 1 is a side view of a sheet-fed screen printing press incorporating a treatment unit to orient the magnetic scales contained in an ink or varnish vehicle, whose treatment unit preferably comprises a cylindrical body;

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Fig. 2 is a schematic perspective view of a part of a cylindrical body suitable for orienting the magnetic scales;

Fig. 3 is a schematic perspective view of annular support rings that are part of the cylindrical body illustrated in fig. 2;

Fig. 4 is a schematic perspective view illustrating the arrangement of the magnetic field induction devices carried by the cylindrical body of figs. 2 and 3 around the axis of rotation of the cylindrical body shown by a dashed line;

Fig. 5 is a side view of a sheet-fed screen printing press incorporating a system according to the invention, which includes a treatment unit preferably comprising a cylindrical body; Y

Fig. 6 is a schematic side view illustrating the cooperation of the treatment unit shown in fig. 5 with the path of the substrate, and in which a drying or curing unit is also provided close to the treatment unit.

Detailed description of embodiments of the invention

The invention will be described below in the context of a screen printing press fed on sheets for printing security documents, in particular banknotes. The screen printing press can be a printing press as illustrated in fig. 1 or any other type of screen printing press, such as that illustrated in a preferred embodiment of fig. 5. The illustrated embodiments show a treatment unit (designated below with reference number 10 *) of the type having a cylindrical body that is in particular adapted for cooperation with a chain conveyor system of the type comprising a plurality of bars clamping separately as described above here. The invention is equally applicable to any other cylindrical configuration that could be installed between the printing group of a screen printing press and delivery station 4. For example, according to a possible alternative embodiment of the invention, the cylindrical body could be part of a treatment unit comprising a plurality of treatment cylinders each with its own sheet tongs. In other words, although the illustrated embodiment shows a cylindrical body adapted to cooperate with a chain conveyor system, it will not be considered as a limiting aspect of the framework of the invention.

In addition, instead of having a single chain conveyor system as illustrated in fig. 1, the printing press could be provided with (see Fig. 5) a first chain conveyor system 31 located upstream of the treatment unit 10 * to transport the sheets to the treatment unit 10 * and transfer the sheets to the cylindrical body 10 (in which case the cylindrical body would comprise its own tweezers to hold an anterior edge of the sheets) and a second chain conveyor system 32 located downstream of the treatment unit 10 * to remove the sheets out of the unit 10 * treatment to delivery point 4.

Furthermore, although the illustrated embodiments show a 10 * treatment unit adapted for the treatment of sheets, the treatment of a continuous band is also considered as a possible implementation of the present invention. It should also be appreciated that the use of a cylindrical body (or cylinder) is only a preferred but advantageous solution. In the context of the present invention, other treatment units could be considered as long as they are suitable for orienting the scales contained in the ink or varnish vehicle applied on the substrate.

Fig. 5 shows a side view of a sheet-fed screen printing press incorporating a system according to the invention, including a treatment unit 10 * preferably comprising a cylindrical body 10. The same reference numbers have been used in the fig. 5 than in fig. 1 to designate the same elements that do not require any other explanation. It is enough to understand that the main difference between the embodiments of fig. 5 and from fig. 1 resides in the fact that the two chain conveyor systems 31, 32 cooperating with the treatment unit 10 * are provided in the embodiment of fig. 5, instead of just one. More precisely, a first chain conveyor system 31 is located upstream of the treatment unit 10 *, while a second chain conveyor system 32 is located downstream of the treatment unit 10 *.

Figs. 2 to 4 illustrate a possible and preferred embodiment of the treatment unit 10 * comprising a cylindrical body 10 of the same type as described in International Application No. WO 2008/102303 A2.

Fig. 2 is a perspective view of a part of the cylindrical body 10. A common tree member has been omitted in this figure, whose common tree member is described in greater detail in International Application No. WO 2008/102303 A2.

As shown in fig. 2, the cylindrical body 10 exhibits an essentially cylindrical outer shape with a clearance 10a extending axially over a length of the cylindrical body 10. Such clearance 10a can accommodate pliers (not shown) to hold an anterior edge of the sheets. In this referenced example, a cover plate 101 is provided on an outer circumference of the cylindrical body 10. This cover plate 101, which is made of a material exhibiting a low magnetic permeability is advantageously fastened on both extremities in the region of the 10th clearance. Clamping means 102, 103 are provided for this purpose, whose clamping means

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they are designed to secure the cover plate 101 in a suitable manner on the outer circumference of the cylindrical body 10. More precisely, the cover plate 101 is supported at one end by first clamping bars 102 and at the other end by second bars of clamping 103. Although this is not shown in detail, the second clamping bars 103 are designed to be movable on the cylindrical body 10 so as to adjust the tension of the cover plate 101.

As further illustrated in fig. 2, the cover plate 101 is provided in this example with a plurality of rectangular openings 101a. The positions of these openings 101a are made to correspond to the positions of magnetic field induction devices located below. The openings 101a are as such optional and preferable if use has been made of a particular type of magnetic field induction devices, such as those described in WO 2005/002866 A1 which are preferably to be arranged in close proximity. with the ink / varnish design that contains the magnetic scales to be oriented. With other types of magnetic field induction devices, openings 101a could be omitted.

A plurality of small openings 101b visible in the upper part of fig. 2 are further provided in this example along a plurality of annular lines shown as dashed lines in the lower part of fig. 2. As described in International Application No. WO 2008/102303 A2, these openings 101b communicate with a plurality of suction outlets located below the cover plate 101 and designed to allow aspiration of the sheet treated against the circumference of the cylindrical body 10.

Fig. 3 is a part view of the cylindrical body 10 illustrated in fig. 2 without the cover plate 101. As this is visible in fig. 3, the cylindrical body 10 comprises a plurality of annular support rings 40 distributed axially along the axis of rotation of the cylindrical body 10. In the illustrated example, five identical annular support rings 40 are provided. An additional ring 45 is provided on the rightmost end of the cylindrical body 10. This additional ring 45 essentially performs the function of supporting the right side of the cover plate 101 shown in fig. 2 and provides symmetry to the entire cylindrical body 10.

Each annular support ring 40 is preferably provided with a peripheral mounting groove 40a and a pair of peripheral support steps 40b extending on each side of the annular mounting groove 40a. A plurality of support members 50 are mounted on the peripheral mounting groove 40a whose support members 50 are designed to receive a corresponding magnetic field induction element (not shown).

Such a magnetic field induction element can be as simple as a permanent magnet as illustrated in fig. 4 of International Application WO 2005/000585 A1 or a device comprising a body of permanent magnetic material whose surface is etched to cause disturbances of its magnetic field as described in International Application WO 2005/002866 A1. Within the framework of the present invention, the magnetic field generating devices can be any type of device capable of producing a magnetic field capable of orienting the magnetic scales contained in the ink / varnish designs applied on the substrate to be treated, such as electromagnets

Fig. 4 is a schematic illustration of said support members 50 according to a possible mounting configuration around the axis of rotation O of the cylindrical body 10. In fig. 4, all other elements of the cylindrical body 10 have been omitted so that all support members 50 are shown in their mounting positions. In the illustrated embodiment, it can be seen that eight support members 50 are provided in each annular support ring 40, thus totaling forty support members 50, each designed to form a corresponding magnetic field induction device for cooperation with a corresponding to the forty different locations of the sheets being treated. According to the illustrated embodiment, it will be understood therefore that the resulting cylindrical body is adapted for cooperation with sheets on the surface of which a grouping of forty designs containing magnetic scales arranged in a matrix of five columns and eight rows has been printed . Such an arrangement is obviously simply illustrative and other provisions could be considered.

With reference again to fig. 3, it can be seen that the peripheral support steps 40b have a diameter such that the support members 50 (and consequently the magnetic field induction devices as well) are almost completely enclosed between the support steps 40b. In other words, the support steps 40b are designed to provide a support on each side of the magnetic field induction devices, along the axis of rotation of the cylindrical body 10.

As is also evident by looking at fig. 3, the peripheral mounting slot 40a preferably exhibits an inverted T-shape for insertion of the support members 50. Each support member 50 exhibits a corresponding T-shape that matches that of the peripheral mounting slot 40a. Each support member 50 is preferably provided with its own fastener 51 (visible in Fig. 4) adapted for cooperation with the peripheral mounting groove 40a of the annular support rings 40 to secure the magnetic field induction devices in its place in any desired position along the peripheral mounting groove 40a. In this way, each magnetic field induction device can be freely adjusted along the circumference of the annular support rings 40, independently of the other magnetic field induction devices arranged in the same annular support ring 40.

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The annular support rings 40 described above (as well as the additional ring 45) are mounted on a common shaft member (not shown - see International Application No. WO 2008/102303 A2) by means of a central opening 400 visible in FIGS. . 2 and 3. Preferably, each ring 40 (and 45) comprises an internal mounting groove 400a that extends parallel to the axis of rotation O of the cylindrical body 10. This internal mounting groove 400a is designed to allow mounting on the rings 40 , 45 at a certain angular position around the common tree member. To this end, a mounting bar (not shown) is secured to a longitudinal part of the common shaft member, whose mounting bar cooperates with the inner mounting grooves 400a of the annular support rings 40. In this way, each annular support ring 40 is precisely positioned with respect to the common shaft member and according to the same common angular reference position.

The support members 50 and the annular support rings 40 are preferably made of aluminum, or any other material that exhibits low magnetic permeability. Advantageously, each annular support ring 40 can be freely adjusted along the axis of the common shaft member, independently of the other annular support rings 40.

More information about the cylindrical body 10 can be found in International application No. WO 2008/102303 A2.

Fig. 6 is a schematic side view illustrating the cooperation of the cylindrical body 10 with the path P of the sheets in fig. 5. As mentioned above, it should be understood that the sheets are being transferred, with the newly printed side (where the ink or varnish vehicle containing the magnetic scales is applied) facing upwards, to the cylindrical body 10 by the system chain conveyor 31 located upstream (not shown in fig. 6 but located on the right side of the cylindrical body 10 in fig. 6) and then removed from the cylindrical body 10 by the chain conveyor system 32 located downstream (no shown in Fig. 6 but located on the left side of the cylindrical body 10 in Fig. 6). The sheets therefore follow a curved path P (from right to left in Figs. 5 and 6) around the outer circumference of the cylindrical body 10, whose cylindrical body 10 is rotated about its axis of rotation O (in the opposite direction to the hands of the clock as illustrated by the arrow in Fig. 6) in synchronism with the movement of the sheets and the movement of the grab bars of the chain conveyor systems 31, 32. More precisely, the cylindrical body 10 is provided with tweezers (not shown) to hold a leading edge of the sheets.

When a new sheet is arriving, the cylindrical body 10 is positioned such that its clamps are brought close to the grab bar of the chain conveyor system 31 those located upstream to allow the transfer of the corresponding sheet over the circumference of the cylindrical body 10 in a manner known as such in the art. The transfer of the sheet from the cylindrical body 10 to the chain conveyor system 32 downstream is done in a similar manner.

The line A in fig. 6 schematically designates the situation in which the sheet is transferred to the cylindrical body 10 from the chain conveyor system 31 located upstream. Similarly, line B in fig. 6 schematically designates the situation in which the sheet is removed from the cylindrical body 10 and transferred to the chain conveyor system 32 located downstream. Lines A and B delimit an angular sector S along the circumference of the cylindrical body 10 in which each sheet is being brought into contact with (or at least in close proximity to) the outer circumference of the cylindrical body 10. This sector angular S defines the region in which the orientation of the magnetic scales is carried out. Although the angular sector S shown in fig. 6 is less than 180 °, this will be considered as illustrative only. The angular sector S may alternatively be chosen as wide as possible, especially greater than 180 °.

According to the invention, at least one drying or curing unit 60 is provided in the vicinity of the treatment unit 10 * to dry or cure the ink or varnish vehicle to fix the orientation of the magnetic scales contained therein while the The substrate is still in contact with the treatment unit 10 * or in close proximity thereto (and to the magnetic field induction devices) before the substrate is removed from the magnetic field induction devices.

More precisely, in the particular and preferred embodiment shown in figs. 5 and 6, the drying or curing unit 60 is located close to the outer circumference of the cylindrical body 10 at an end downstream of the angular sector S.

In this way, drying or curing of the ink or varnish vehicle can be carried out before the actual separation of the substrate from the treatment unit, thereby avoiding the problems mentioned in the preamble.

It will be understood that drying or curing of the ink or varnish vehicle does not necessarily need to be complete, that is, it may be enough to partially dry or induce partial curing of the ink or varnish vehicle to prevent the scales from moving too much during substrate separation. of the treatment unit. In this regard, it may still be necessary to provide an additional drying or curing unit 5 along the path of the sheet downstream of the treatment unit 10 * as shown in fig. 5. Having said that, the drying or curing unit 60 may be of a type suitable for drying or almost completely curing the ink or varnish vehicle, without the need for an additional drying or curing unit 5.

According to the invention, the drying or curing unit 60 is a UV curing unit comprising elements of

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LEDs that produce radiation in the UV range (or "UV-LED curing elements"), whose LED elements are arranged in the form of a longitudinal bar that extends transversely to the substrate path.

Various modifications and / or improvements can be made in the embodiments described above without departing from the scope of the invention as defined by the appended claims. For example, although the invention has been described in the context of a printing press adapted to print sheets, the invention is equally applicable to the printing of a continuous web of material.

In addition, although screen printing is a preferred printing process for applying ink / varnish designs that contain the magnetic scales to be oriented, other printing processes, such as the printing process by engraving ("intaglio" ") as described in European patent application EP 1

10 650 042 A1. In other words, the present invention can be adapted to any suitable printing process and printing press.

Finally, the solution described in International Application No. WO 2008/139373 A1 may be conveniently used in the name of the present applicant.

Claims (12)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 1. System for orienting magnetic scales contained in an ink or varnish vehicle applied on a sheet-shaped or band-shaped substrate, whose system comprises a treatment unit (10 *) with at least one magnetic field induction device to orient the magnetic scales contained in the ink or varnish vehicle applied on the substrate, whose treatment unit (10 *) is located along a path (P) of the substrate such that the substrate is brought into contact with the treatment unit (10 *) or in close proximity thereof and at least to said magnetic field induction device, wherein the system further comprises at least one drying or curing unit (60) arranged in the vicinity of the treatment unit (10 *) to dry or cure the ink or varnish vehicle to set the orientation of the magnetic scales contained in it while the substrate is still in contact with the treatment unit (10 *) or in close proximity thereto and at least to said magnetic field induction device before the substrate is removed from at least said induction device of magnetic field, characterized in that at least said drying or curing unit (60) is a UV curing unit comprising LED elements that produce radiation in the UV range, whose LED elements are arranged in the form of a longitudinal bar that extends transversely to the substrate path .

2.

 System according to claim 1, wherein the treatment unit (10 *) comprises a cylindrical body (10) and wherein at least said magnetic field induction device is disposed on an outer circumference of the cylindrical body (10).

3.

System according to claim 2, wherein the substrate is brought into contact with the outer surface of the cylindrical body (10) or close proximity thereof over a selected angular sector (S) and in which at least said unit (60) drying or curing is located close to the outer circumference of the cylindrical body (10) of one end downstream of the selected angular sector (S).

Four.

 System according to claim 1 or 2, wherein said cylindrical body (10) comprises a plurality of magnetic field induction devices distributed over the outer circumference of the cylindrical body (10).

5.

 System according to claim 4, wherein the cylindrical body (10) further comprises a plurality of distinct annular support rings (40) axially distributed along a common shaft member, each annular support ring (40) carrying an assembly of said magnetic field induction devices that are circumferentially distributed over an outer circumference of the annular support rings (40).

6.

System according to claim 5, wherein each of said annular support rings (40) can be freely adjusted along the axis of the common shaft member, independently of the other annular support rings (40).

7.

System according to claim 1, wherein the treatment unit (10 *) comprises a plurality of magnetic field induction devices distributed in a matrix-shaped arrangement to orient the magnetic scales contained in a plurality of ink or varnish designs applied on the substrate in a corresponding matrix arrangement.

8.

Process for orienting magnetic scales contained in an ink or varnish vehicle applied on a sheet-shaped or band-shaped substrate, the process of which includes the following operations:

(to)

 bringing the substrate into contact with at least one magnetic field induction device or in close proximity thereof to orient the magnetic scales contained in the ink or varnish vehicle applied on the substrate, and

(b)

 Dry or cure the ink or varnish vehicle to fix the reorientation of the magnetic scales contained therein,

wherein the operation (b) is performed while the substrate is still in contact with at least said magnetic field induction device or in close proximity thereof before the substrate is removed from at least said magnetic field induction device , characterized in that this operation (b) includes the application of UV radiation to the substrate using LED elements that produce radiation in the UV range, whose LED elements are arranged in the form of a longitudinal bar that extends transversely to the substrate path.

9.

Process according to claim 8, wherein the operation (a) includes bringing the substrate into contact with a cylindrical body (10) or in close proximity thereof that carries at least one of said magnetic field induction devices on an outer circumference of the cylindrical body (10).

10.

Process according to claim 9, wherein the substrate brought into contact with the outer circumference of the cylindrical body (10) or in close proximity thereof over a selected angular sector (S) and in which the operation

(b) includes drying or curing the ink or varnish vehicle containing the magnetic scales at an end downstream of said selected angular sector (S). 9

eleven.

 Use of the system according to any of claims 1 to 7 for the production of security documents, such as banknotes.

12.

 Printing press comprising a system according to any one of claims 1 to 7.

10