Patent Application
20190381785
The present invention generally relates to a printing press—especially an offset printing press—adapted to carry out printing on a sheet-like or web-like substrate, in particular for the production of security documents such as banknotes, comprising a printing unit designed to print a first side and/or a second side of the substrate. The invention especially relates to a printing press preferably comprising a printing unit with at least a printing group designed to print a first side and/or a second side of the substrate by collecting different impressions respectively ink patterns in their respective colours on a cylinder, e. g. a collecting cylinder, in advance before being printed onto the substrate.
Offset printing presses for the production of security documents such as banknotes are known as such in the art, in particular from European Patent Publication No. EP 0 949 069 A1 and International PCT Publications Nos. WO 2007/042919 A2, WO 2007/105059 A1, WO 2007/105061 A1, WO 2008/099330 A2 and WO 2016/071870 A1, which publications are all incorporated herein by reference in their entirety.
International PCT Publication No. WO 2007/042919 A2 in particular discloses a recto-verso offset printing press adapted for simultaneous recto-verso printing of sheets that further comprises an additional printing group placed upstream of a main printing group of the printing press.
Applicant under the product designation Super Simultan® IV. The basic configuration of the printing press 100 shown in
This printing press 100 comprises a printing unit 2, which is specifically adapted to perform simultaneous recto-verso printing of the sheets (according to the so-called Simultan-offset printing principle) and comprises, as is typical in the art, two blanket cylinders (or printing cylinders) 5, 6 rotating in the direction indicated by the arrows and between which the sheets are fed to receive multicolour impressions. In this example, blanket cylinders 5, 6 are three-segment cylinders which are supported between a pair of side frames designated by reference numeral 20. The blanket cylinders 5, 6 receive and collect different ink patterns in their respective colours from plate cylinders 15 and 16 (four on each side) which are distributed around a portion of the circumference of the blanket cylinders 5, 6. These plate cylinders 15 and 16, which each carry a corresponding printing plate, are themselves inked by corresponding inking apparatuses 25 and 26, respectively. The plate cylinder 15, 16 together with the associated inking apparatus 25, 26 hereby form a kind of colour separation delivery branch, delivering the respective separation for collecting on the respective blanket cylinder 5, 6. The two groups of inking apparatuses 25, 26 are advantageously supported in two inking carriages 21, 22 that can be moved toward or away from the centrally-located plate cylinders 15, 16 and blanket cylinders 5, 6.
As is known in the art, each printing plate is wrapped around the corresponding plate cylinder 15, 16 and clamped at its leading end and trailing end by a suitable plate clamping system, which plate clamping system is located in a corresponding cylinder pit of the plate cylinder (see e.g. International (PCT) Publications Nos. WO 2013/001518 A1, WO 2013/001009 A1 and WO 2013/001010 A2, which are also incorporated herein by reference in their entirety).
Sheets are fed from a substrate delivery unit 1, e. g. sheet feeder 1 onto a feeder table 1* located next to the printing unit 2 (on the right-hand side in
In the example of
In the example of
The printing press of
The relevant micro-optical structures are typically applied in a separate and dedicated process, in particular in combination with transparent windows that are formed in the substrate material, whether prior to or during the formation of the relevant micro-optical structures. Known processes for creating such micro-optical structures are disclosed for instance in European Patent Publication No. EP 1 878 584 A2 and International Publications Nos. WO 94/27254 A1, WO 2007/020048 A2, WO 2014/125454 A1, WO 2015/022612 A1 and WO 2015/107488 A1, which publications are likewise incorporated herein by reference.
The WO 2015/022612 A1 more precisely discloses a substrate with a window region filled with transparent polymer material and with a micro-optical structure covering the filling on one side of the window region. Furthermore there are disclosed two alternative methods and a device to create such an substrate. Such provided substrate as part of the production of security can be printed on the side opposing the micro-optical structure.
Application of a separate and dedicated process to create the necessary micro-optical structures is however cumbersome and adds up to the complexity and cost of the production of the relevant security features and documents incorporating the same. There is therefore a need for an improved solution, especially such a solution that streamlines and simplifies the production of documents that are to be provided with security elements incorporating micro-optical structures.
A general aim of the invention is to improve the known printing presses of the aforementioned type.
More precisely, an aim of the present invention is to provide such a printing press that allows to achieve high register between micro-optical structures to be provided on the substrate material and the printed patterns to be printed in combination with such micro-optical structures.
Another aim of the present invention is to provide such a printing press where machine operability and accessibility are not compromised.
These aims are achieved thanks to the printing press defined in the claims. In particular there is provided a printing press adapted to carry out printing on a sheet-like or web-like substrate, in particular for the production of security documents such as banknotes, comprising a printing unit designed to print a first side and/or a second side of the substrate in register with an inline applied optical structure, the printing press preferably comprising a printing unit with at least a printing group designed to print a first side and/or a second side of the substrate by collecting different ink patterns in their respective colours and/or several impressions from several plate cylinders on a cylinder, e. g. collecting cylinder, in advance before being printed as a whole onto the substrate. Such printing group further shortly is named as impressions collecting group or, as further cited, collect printing group.
Instead or preferably in addition to the above, in a preferred embodiment the printing group is designed as printing group for indirect printing, such as indirect lithographic printing, i.e. offset printing, or an indirect relief printing, e. g. letterset printing, or a combination with both of them.
The printing unit or especially the collect printing group preferably can be configured with at least one or more inking apparatuses and associated plate cylinders designed to enable and/or carry out offset printing, comprising for example a dampening system and/or at least the possibility to place lithographic printing plates onto the respective plate cylinder. Although these inking apparatuses possibly can also be run for letterset printing without or with inactive dampening system and with a letterpress printing plate, the printing group or printing unit nevertheless is designed—at least partly—as an offset printing group respectively printing unit. In addition to plate cylinders and inking apparatuses designed to enable and/or carry out offset printing a collect printing group or unit can comprise additional plate cylinders with associated inking apparatuses designed to especially carry out only other kinds of printing, for example letterset printing. In this sense, the above collect printing unit or group shall be understood as an offset printing unit or group, provided at least one, more or all of its plate cylinders and corresponding inking apparatuses is or are designed to enable and/or carry out offset printing.
In an alternative embodiment, the printing unit or especially the collect printing group can be configured only with one or more plate cylinders and associated inking apparatuses designed to enable and/or carry out indirect relief printing, e.g. such as letterset printing.
According to the invention, the printing press further comprises an in-line casting device adapted to apply a layer of material acting as an optical medium on a portion of the first or second side of the substrate and to replicate and form a micro-optical structure in the layer of material acting as optical medium. Furthermore, the printing unit is adapted to print at least one printed pattern on the first or second side of the substrate in register with the micro-optical structure. The term “first” side and “second” side for the sides of the substrates are arbitrarily chosen and can be inverted.
In accordance with a preferred embodiment of the invention, the in-line casting device comprises at least one application unit, e. g. a screen-printing unit acting as application unit, for applying at least a part of the layer of material acting as optical medium. In the context of the present invention, more than one application unit, e. g. screen-printing unit, could be provided, especially if the quantity of material acting as the optical medium is to be increased. Other processes than screen printing could furthermore be contemplated to apply the relevant material acting as optical medium, it being however to be appreciated that screen printing remains a preferred process in the context of the invention. An alternative may for instance consist in using a flexographic-printing unit as the respective application unit. According to another preferred embodiment of the invention, the in-line casting device may advantageously comprise at least one embossing tool with an embossing form, e. g. an embossing cylinder, acting as carrier supporting a replicating medium designed to replicate and form the micro-optical structure in the layer of material acting as optical medium. In this context, it is particularly advantageous to additionally provide at least one pressure cylinder or roller cooperating with the embossing cylinder to press the substrate against the replicating medium, which ensures optimal replication and formation of the relevant micro-optical structures. The aforementioned embossing cylinder could in particular be located immediately after the aforementioned application unit.
In a preferred embodiment, the material acting as optical medium preferably can be applied directly onto the substrate before being brought into contact with the embossing tool, i.e. the embossing cylinder. The application in this case is being placed at the substrate path upstream the embossing tool.
In an alternative embodiment, the material acting as optical medium can be applied directly onto the embossing form, e. g. onto the surface of the embossing cylinder before the substrate being arranged on it. The application unit in this case is being placed at the embossing tool, preferably at the circumference of the embossing cylinder, especially in a peripheral section between delivery and take over of the substrate.
Although the casting device can be designed that the embossing cylinder to act onto the substrate only in a nip with a transport or conveying cylinder carrying the substrate, in a preferred embodiment, the embossing cylinder acts as a transport or conveying cylinder carrying and/or supporting the substrate over a—especially significant—angle range, e. g. for at least 90° of revolution.
By way of preference, the printing press could further comprise a washing device that can selectively be brought in contact with the embossing cylinder during maintenance operations to clean the surface of the embossing cylinder. This would be particularly advantageous in facilitating removal of residues of the material used to form the micro-optical structure.
Furthermore, the printing press could advantageously be designed as a sheet-fed printing press adapted to carry out printing on individual sheets, wherein transfer of the sheets between the in-line casting device and the printing unit is carried out exclusively from cylinder to cylinder via cooperating cylinder grippers, which solution ensure optimal register accuracy between the print and the associated micro-optical structure.
According to a further embodiment of the invention, the in-line casting device could further be provided with at least one drying/curing unit (preferably a UV-curing unit, advantageously such as a UV-LED curing unit) to dry or cure the layer of material acting as optical medium during and/or following replication of the micro-optical structure in the layer of material acting as optical medium.
This could advantageously be performed by means of a drying/curing unit located to dry or cure the layer of material acting as optical medium from the side of the substrate which is opposite to the side of the substrate where the micro-optical structure is replicated, especially while the substrate is still being processed on the aforementioned embossing cylinder (in which case the drying/curing unit is to be located about a portion of the circumference of the embossing cylinder.
Alternatively, or in addition to the above measures, a drying/curing unit could be located to dry or cure the layer of material acting as optical medium from the side of the substrate where the micro-optical structure is replicated, especially while the substrate is being transported by a transfer cylinder located immediately after the aforementioned embossing cylinder (in which case the drying/curing unit is to be located about a portion of the circumference of this transfer cylinder).
The printing press of the invention can in particular be of a type where the printing unit is designed to operate as an indirect printing unit, e.g. such as an offset or indirect relief printing unit in the above sense, especially a Simultan-type printing unit, especially Simultan-type offset printing unit—preferably in the above sense—for the simultaneous recto-verso printing of the substrate.
By way of preference, the micro-optical structure is replicated by the in-line casting device upstream of a location where the printed pattern is printed by the printing unit. Within the scope of the present invention, the in-line casting device could however be provided at any appropriate location in the printing press, be it after the relevant printing unit or between two printing units, or even form an integral part of a printing unit.
Further advantageous embodiments of the invention form the subject-matter of the dependent claims and are discussed below.
Other features and advantages of the present invention will appear more clearly from reading the following detailed description of embodiments of the invention which are presented solely by way of non-restrictive examples and illustrated by the attached drawings in which:
Although the present invention in principle is not limited to such an embodiment of the printing press respectively printing unit, it will be described in the particular context of preferred embodiments of a printing press, preferably sheet fed printing press, comprising a printing unit with at least a printing group (91; 92; 93; 94) designed as an collect printing group (91; 92; 93; 94) as mentioned above and/or a, preferably sheet-fed, recto-verso printing press, especially based on indirect printing, exhibiting a (m)-over-(m) configuration (see embodiment of
An collect printing group (91; 92; 93; 94) is designed to print at least one side of the substrate by firstly collecting several impressions or patterns from several plate cylinders on a cylinder, e. g. a so called collecting cylinder, before being printed as a collected image as a whole onto the substrate.
In the context of the present invention, the expression “printing cylinder(s)” will be used to designate the relevant cylinders of a printing group (91; 92; 93; 94), e.g. of a main printing group (91, 92) and of any additional printing group (93, 94), that directly cooperate with the first and second sides of the substrates (e.g. sheets) to transfer printing patterns thereon. This expression preferably is interchangeable with the expression “transfer cylinder” or “blanket cylinder”, it being to be understood that the relevant printing cylinders for example each carry an number, e. g. one or several, printing blankets.
The expression “printing group” (91; 92; 93, 94) will be used for the equipment, e.g. the cylinders, rollers and the means of the inking unit(s), belonging to a printing nip for at least printing on one side of the substrate. A double sided printing group (91, 92; 93, 94) therefor is a special printing group (91, 92; 93, 94) with two printing groups (91; 92; 93; 94), one on or for each side of the substrate path, sharing a same printing nip for printing simultaneously both sides of a passing substrate and mutually acting with its printing cylinders as counter-pressure cylinders for the other printing group (92; 91; 94; 93).
It is to be understood, that several printing groups 91; 92; 93; 94 can be arranged in a same printing unit 2; 2*; 2**; 2***; 2****, with these printing groups 91; 92; 93; 94 for example being arranged in single- or multi-part frame walls.
The expression “first side” (designated by reference I) and “second side” (designated by reference II) are used in the following description to designate the two opposite sides of the sheets being printed. More precisely, in the illustrations of
In accordance with the invention, one wishes to replicate a micro-optical structure L on one or the other side of the substrate S. More precisely, according to the illustrated example, one wishes to replicate a micro-optical structure L, such as a field of micro-lenses, on top of the window W, on the second side II of the substrate S. To this end, side II of the substrate S is first provided in the relevant portion of the substrate S with a layer of material acting as an optical medium (for instance by means of a suitable screen-printing unit as discussed hereafter) before being brought into contact with and pressed against the surface of a replicating medium RM that is provided with a corresponding replicating structure (formed as a recessed structure in the surface of the replicating medium RM). Any desired shape and geometry could be imparted to the replicating structure in order to form the desired micro-optical structure L.
As schematically illustrated in
Subsequent to, or preferably during the replication process, the relevant material acting as optical medium is subjected to a drying or curing process (especially a UV-curing process). This is preferably carried out, as schematically illustrated in
It should be appreciated that the invention is equally applicable to other types of substrates than the one illustrated in
The printing press 100* in this embodiment comprises a printing group 91, 92, especially as a main printing group 91, 92, which comprises two printing groups 90; 91, one for each side of the substrate path, forming a so-called double sided printing group 91, 92 for simultaneous printing on both sides. This double sided printing group 91, 92 consists of elements 5, 6, 15, 16, 25, 26, including first and second printing cylinders 5, 6 cooperating with one another to form a first printing nip between the first and second printing cylinders 5, 6, especially transfer cylinder, where the first and second sides I, II of the sheets S are simultaneously printed, the first printing cylinder 5 acting as a sheet conveying cylinder of the main respectively double sided printing group. The configuration of the main printing group for example is as such identical to that of the main printing group illustrated in
In contrast to the configuration illustrated in
In a variant of the first embodiment depicted in
In this and in the following embodiments, the press 100* or printing unit 2 or main printing group 91; 92 comprises at least one printing group 91; 93 on that side of the substrate path for printing onto the substrate side I; II which opposes the side II, I having already been or still have to be provided with the micro-optical structure upstream. Preferably, this at least one printing group 91; 93 is designed as above mentioned collect printing group 91; 93.
By way of preference—at least for embodiments with application of the material directly onto the substrate—the in-line casting device 80 depicted in
In principle, the application unit could alternatively be designed to apply a layer of material acting as the optical medium on a portion of the first side I of the sheets S (for instance on a window-forming region W formed in the substrate S as depicted in
The aforementioned screen-printing unit 82, 82a, 84 is designed to act a first application unit for applying the required layer of material where the micro-optical structure is to be replicated. The configuration and operation of the screen-printing unit 82, 82a, 84 is known as such in the art and does not need to be described in detail. Reference can in particular be made to European Patent Publication No. EP 0 723 864 A1 in the name of the present Applicant, which is incorporated herein by reference in its entirety.
In the illustration of
Downstream of the impression cylinder 84, there is preferably provided at least one embossing cylinder 85, serving as embossing tool, which cooperates with the second side II of the sheets S, i.e. the side where the layer of material acting as optical medium was applied by the application unit 82, 82a, 84, especially screen-printing unit 82, 82a, 84. This embossing cylinder 85 preferably carries on its circumference a replicating medium RM (as schematically illustrated in
A pressure roller or cylinder 86 is furthermore advantageously provided about the circumference of the embossing cylinder 85 in order to cooperate with the first side I of the sheets S and press the sheets S against the circumference of the embossing cylinder 85 (and the surface of the replicating medium RM located thereon), thereby ensuring proper replication of the micro-optical structure L into the layer of material acting as optical medium.
The in-line casting device 80 further comprises a first drying/curing unit 51 located about a portion of the circumference of the embossing cylinder 85, downstream of the possibly pressure roller or cylinder 86, to dry or cure the layer of material acting as optical medium while the sheets S are still being processed and pressed against the circumference of the embossing cylinder 85 and the surface of the replicating medium RM located thereon, thereby ensuring optimal replication and formation of the desired micro-optical structure L. In this context, it shall be understood that the drying/curing operation is carried out from the side opposite to the side being provided with the layer to be cured, here for example the first side I of the substrate, e.g. sheets S, which is especially adequate in the event that the micro-optical structure L is replicated on top of a window-forming portion W as schematically illustrated in
Alternatively, or in addition to the aforementioned drying/curing unit 51, the in-line casting device 80 could be provided with a (second) drying/curing unit 52 located about a portion of the circumference of a transfer cylinder 87 that is located immediately after the embossing cylinder 85 as depicted in
The aforementioned drying/curing units 51, 52 could advantageously be UV-curing units, especially UV-LED curing units, in which case the relevant layer of material acting as optical medium evidently has to be a UV-curable material.
Subsequent to the replication of the micro-optical structure L, the sheets S are transferred to the downstream-located printing unit 2*, namely to the sheet transfer cylinder 10.
In accordance with this first embodiment, the sheets S are accordingly fed in succession from the sheet feeder (not shown in
It will therefore be appreciated in this embodiment that the sheets S are initially provided with micro-optical structures L on side II and then receive at least first impressions on the opposite side I, preferably first and second impressions on both sides I, II, which impressions are performed simultaneously at the printing nip between the first and second printing cylinders 5, 6 of the main printing group 91, 92. It will also be appreciated that transfer of the sheets S from the in-line casting device 80 to the printing unit 2* is carried out exclusively from cylinder to cylinder via cooperating cylinder grippers. Optimal register accuracy between the micro-optical structures L that are replicated by means of the embossing cylinder 85 and the impressions performed by the printing unit 2* is thereby guaranteed.
This printing press 100** shares a number of common features with the first embodiment of
Alternatively, the sets of inking apparatus 25, 27 on the right side of the printing unit 2 and/or the sets of inking apparatus 26, 28 on the left side of the printing unit 2 could be supported in one and a same inking carriage (one on each side).
In the illustrated example, the additional printing group 93, 94 with the basic components 7, 8, 17, 18, 27, 28 is placed upstream of and above the main printing group 91, 92, the first and second printing cylinders 5, 6, on the one hand, and the third and fourth printing cylinders 7, 8, on the other hand, being advantageously aligned along two horizontal planes.
The main printing group 91, 92, comprising the basic components 5, 6, 15, 16, 25, 26, and the additional printing group 93, 94, comprising the basic components 7, 8, 17, 18, 27, 28, are coupled to one another by means of an intermediate sheet conveying system comprising, in the illustrated embodiment, first to third sheet-transfer cylinders 10′, 10″, 10′″ interposed between the first and third printing cylinders 5, 7. More precisely, the sheets printed in the additional printing group 93, 94 are transferred from the third printing cylinder 7 in succession to the first sheet-transfer cylinders 10′, to the second sheet-transfer cylinders 10″, to the third sheet-transfer cylinder 10′″, and then to the first printing cylinder 5 of the main printing group 91, 92.
On their way to the main printing group 91, 92, the sheets are preferably dried/cured by third and fourth drying/curing units 55, 56. As illustrated, the third drying/curing unit 55 advantageously cooperates with the first sheet-transfer cylinder 10′, i.e. the sheet-transfer cylinder located immediately downstream of the third printing cylinder 7, and the fourth drying/curing unit 56 cooperates with the second sheet-transfer cylinder 10″. The drying/curing units 55, 56 are advantageously UV curing units, preferably UV-LED curing units.
Drying/curing of the second side II of the sheets could alternatively be performed directly onto the third printing cylinder 7, provided suitable measures are taken to ensure that the drying/curing unit does not degrade the performance or usability of the printing blankets on the third printing cylinder 7.
In accordance with this other embodiment, the sheets S are accordingly fed in succession from the sheet feeder (not shown in
It will therefore be appreciated that the sheets S are initially provided with micro-optical structures L on side II and then receive first and second impressions on both sides I, II, which impressions are performed simultaneously at the printing nip between the third and fourth printing cylinders 7, 8 of the additional printing group and at the printing nip between the first and second printing cylinders 5, 6 of the main printing group. It will likewise also be appreciated that transfer of the sheets S from the in-line casting device 80 to the printing unit 2** is carried out exclusively from cylinder to cylinder via cooperating cylinder grippers. Optimal register accuracy between the micro-optical structures L that are replicated by means of the embossing cylinder 85 and the impressions performed by the printing unit 2** is once again guaranteed.
The embodiment with direct application onto the embossing cylinder 85 described in the context of the first embodiment is to be transferred to the second embodiment.
It should be appreciated that the actual numbers m and n of plate cylinders 15, 16, 17, 18 illustrated in
As a possible refinement of the invention, as illustrated in
Furthermore, the printing presses 100* of
Various modifications and/or improvements may be made to the above-described embodiments without departing from the scope of the invention as defined by the annexed claims. In particular, while the embodiments of the invention where described with reference to sheet-fed printing press configurations, the invention could equally be applied to print on web-like substrates, i.e. successive portions of a continuous web of printable material.
Furthermore, the in-line casting device could be adapted to apply a layer of material acting as an optical medium on a portion of either the first or second side of the substrate and to replicate and form the micro-optical structure accordingly. In that respect, the configurations of the in-line casting devices 80, 80*, 80** shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 17157503.8 | Feb 2017 | EP | regional |
| 17167792.5 | Apr 2017 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/054103 | 2/20/2018 | WO | 00 |
