GB2569850A - Registration system and method of use thereof - Google Patents

Registration system and method of use thereof Download PDF

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Publication number
GB2569850A
GB2569850A GB1817276.7A GB201817276A GB2569850A GB 2569850 A GB2569850 A GB 2569850A GB 201817276 A GB201817276 A GB 201817276A GB 2569850 A GB2569850 A GB 2569850A
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United Kingdom
Prior art keywords
registration
station means
station
print
substrate
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Granted
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GB1817276.7A
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GB2569850B (en
GB201817276D0 (en
Inventor
Collinson Steven
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Emerson and Renwick Ltd
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Emerson and Renwick Ltd
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J11/00—Devices or arrangements  of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
    • B41J11/36—Blanking or long feeds; Feeding to a particular line, e.g. by rotation of platen or feed roller
    • B41J11/42—Controlling printing material conveyance for accurate alignment of the printing material with the printhead; Print registering
    • B41J11/46—Controlling printing material conveyance for accurate alignment of the printing material with the printhead; Print registering by marks or formations on the paper being fed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J11/00—Devices or arrangements  of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
    • B41J11/008—Controlling printhead for accurately positioning print image on printing material, e.g. with the intention to control the width of margins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J15/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in continuous form, e.g. webs
    • B41J15/16—Means for tensioning or winding the web

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  • Inking, Control Or Cleaning Of Printing Machines (AREA)

Abstract

A registration system is provided including a first station with means for applying a tension to a substrate passing through the same in use, and at least one further stations 8, 12, 14 provided downstream of the first station means arranged for printing (e.g. gravure printing cylinder 5) and/or embossing one or more patterns or marks on the substrate. Registration mark detection means S1-3 associated with the stations for detect at least one registration mark 2 on the substrate. Control means 18 are provided for calculating a first alignment error of the detected registration mark(s) with respect to the first station, and for calculating at least one further alignment error of the detected registration mark(s) with respect to each of the further stations. The control means is arranged to calculate a virtual alignment error for each of said further station means by taking the calculated alignment error of each station means and comparing it to the first alignment error. Preferably this is used in conjunction with angular position data of cylindrical rollers associated with each further (printing) station, with rotation of said rollers controlled in order to align the printing.

Description

This invention relates to a registration system and to a method of use thereof.
Although the following description refers almost exclusively to a print registration system for use on a continuous web of material, such as for example wallpaper, via a gravure printing process, it will be appreciated by persons skilled in the art that the registration system of the present invention could be apphed to either continuous or non-continuous substrates, it could be used with any type of printing and/or embossing apparatus, such as screen printing for example, and could include materials other than paper, such as for example, fabric, board material, plastic material and/or the like, for any suitable apphcation.
Most wallpaper print designs are made up of several different colours; each colour apphed to the waUpaper substrate material by separate printing stations in an inline printing apparatus. In order to achieve a desired visual effect, each colour needs to be precisely aEgned and in register with the other colours of the print design. After each ink colour has been printed on the web material, the ink needs to be stabihsed or dried before the next ink colour can be appEed. A drying oven is often located on the print line in between print stations in order to achieve this. The heat produced by the drying oven, together with the several metres of line/path length needed to accommodate it, makes it difficult to achieve accurate registration between appbcation of the different ink colours without some form of print registration control system being provided.
A print registration system provides a ‘register mark’ on the substrate material for each different ink colour used in the print design. Contrast sensors are used to detect the register marks and measure any misahgnment between the marks and the print rollers at the print stations. Once any misahgnment errors have been precisely measured, the printing control system then tries to eliminate the errors by adjusting one or more operational parameters of the print roEers.
An example of a conventional print registration system is known as “web-web register control”, in which registration marks are integrated into a main print design applied to a front surface of the substrate material (i.e. on the same surface of the substrate material to which the print design is to be applied in use).
For a three colour printing press/apparatus having three separate print stations:
A sensor CS1’ located after print station 2 compares register marks printed on a front surface of the substrate material by print stations 1 and 2 upstream of SI to detect an alignment error;
A sensor ‘S2’ located after print station 3 compares register marks printed on the front surface of the substrate material by print stations 1 and 3 upstream of S2 to detect an alignment error.
While web-web register control is widely used for high accuracy printing systems, it has fundamental problems. Some of the ink colours can be difficult to detect by the contrast sensors. For example, very pale ink colours may only be visible under special lighting conditions or may be almost invisible until after further processing. The register marks in this register control system form part of the print design on the front surface of the substrate and therefore a relatively complex and sophisticated system is needed to correctly locate the register marks. In addition, if detected alignment errors are too large, the system can fail because the register marks from one print station may be printed over by a later print station in the print line.
An example of an alternative print registration system is known as “web-cylinder register control”. This system only requires a single printed mark, known as the key-mark, to be integrated into the main print design on the substrate material. The key mark is usually provided by the first print station in the print line of the apparatus. The position of the later printed different colour ink patterns is inferred from the position of the printing cylinder associated with each different ink colour.
For a three colour printing press having three separate print stations for webcylinder register control:
The Key-mark is printed on the front surface of the web material by print station 1;
A sensor ‘SI’ after print station 2 compares the key-mark with the position of the print cylinder of print station 2;
A sensor ‘S2’ after print station 3 compares the key-mark with the position of the print cylinder of print station 3.
Web-cylinder register control is not as accurate as web-web register control, but it is often good enough for many applications and is more flexible. However, webcylinder register control is not without its problems. A good key-mark needs to be printed before later print stations can use web-cylinder control. If the key-mark is difficult to detect for any reason, such as it being printed from a relatively pale ink colour, the register control system will not work properly. The key-mark needs to co-ordinate with the ink colour patterns printed by print stations downstream of the key-mark printer. A relatively complex and sophisticated register control system is therefore still required to correctly locate the key-mark and, during higherror conditions, it can be over-printed as with the web-web system. Thus, in the web-cylinder registration system, all the different ink colour patterns printed need to be compatible with the register system to either print the key-mark or make room for the key-mark within the print pattern.
An example of a further print registration mark system is known as a ‘back-mark register system’ and is illustrated with reference to the print process 1 shown in Figure 1. In this system, a key-mark 2 is printed by a separate printer on a rear surface 4 of the substrate material 6 (i.e. the surface opposite to the surface on which the main print pattern is provided) as it moves through the print apparatus according to arrow 3. The key-mark 2 is printed on the rear of the substrate material 6 in a pre-print step before it reaches the first print station 8 that prints the main print pattern on the front surface of the substrate material. This pre-print step can be undertaken by a simple printer, such as an ink jet printer 10 located upstream of the first print station 8. Each print station 8, 12, 14 of the print apparatus in this example comprises a gravure print roller 5 with an opposing roller 7 forming a ‘grip’ or tension ‘nip’, between which the substrate material 6 passes as it moves through the print apparatus. Each print station 8, 12, 14 prints a different ink colour of the repeat print pattern being printed by the print apparatus. An ink collection tray 16 is provided with each print station to supply the printer roller 5 with ink.
A motion controller (not shown) can be used to generate position data of an electronic line shaft 17. This position data is transmitted to control means 18 associated with each of the print stations to allow synchronisation of the rollers in the print apparatus.
This back mark registration system removes many of the problems associated with conventional web-web or web-cylinder register control systems. Thus, any ink colour can be included in the main print design on the substrate material without a problem. The system is easy to control and is robust. Since the key-mark is separated from the main print design, it is easy to detect as it is never over-printed. The print cylinders in this system do not need to be designed specifically for the register system. In addition, because the key-mark does not need to coordinate with the main print design, there are few restrictions on its layout. In particular, better control can be achieved by having several key marks per print repeat of the print design.
For a three colour printing press having three separate print stations (8, 12, 14) for back mark register control:
Ink jet printer (10) located upstream of print station 1 (8) prints the key-mark on the rear surface (4) of the substrate material (6);
A sensor CS1’ after print station 1 (8) compares the key-mark (2) with the position of print cylinder 1 (5) at print station 1 (8) to generate a first alignment error (Error
i);
A sensor ‘S2’ after print station 2 (12) compares the key-mark with the position of print cylinder 2 (5) at print station 2 (12) to generate a second alignment error (Error 2);
A sensor ‘S3’ after print station 3 (14) compares the key-mark with the position of print cylinder 3 (5) at print station 3 (14) to generate a third alignment error (Error
3)·
Control means 18 in the form of micro-processing means are provided with each print station 8, 10, 14. The sensors CS1’, ‘S2’ and ‘S3’ each communicate registration mark detection data to its associated micro-processing means 18, and said micro-processing means calculates an alignment error for each registration mark with respect to the position of the print roller 5 of the associated print station. The micro-processing means 18 then uses this calculated alignment error to control the speed and/or angular position of the print roller, as shown by path
20.
However, even with the back-mark register control system, problems are encountered. As the back-mark is used as the key-mark, the registration accuracy of the entire print process is determined by how well the registration mark is synchronized with other ink patterns of the main print design being printed on the front surface of the substrate. The back-mark printer needs to be of high quality and be accurately synchronized with the other ink printers used in front surface print stations of the system. Although the back-mark register system works well for stable substrates, such as paper substrate, it can be more difficult on substrates made from plastic film, for example. This is because the type of printer used for printing the back-mark does not normally ‘grip’ the web material like the print cylinders used in front surface print stations, such as for example gravure print cylinders. Front surface registration marks printed by a gravure print cylinder are more uniformly spaced than those printed by a tear surface non-grip printer. As such, a back-mark system where all of the front surface prints register to a nongrip printed mark will not be as accurate as a front mark system where a key mark is printed by a gravure print cylinder and subsequent print registers to this key mark.
It is therefore an aim of the present invention to provide a registration system that overcomes the abovementioned problems.
It is a further aim of the present invention to provide a print and/or emboss registration system.
It is a further aim of the present invention to provide a method of using a registration system.
It is a further aim of the present invention to provide a method of using a print and/or emboss registration system.
It is a yet further aim of the present invention to provide apparatus including a registration system.
It is a yet further aim of the present invention to provide print and/or emboss apparatus including a print and/or emboss registration system
It is a yet farther aim of the present invention to provide a method of using apparatus including a registration system.
It is a yet further aim of the present invention to provide a method of using print and/or emboss apparatus including a print and/or emboss registration system.
According to a first aspect of the present invention there is provided a registration system, said system including first station means for applying a tension to a substrate passing through the same in use, and at least one further station means provided downstream of the first station means arranged for printing and/or embossing one or more patterns or marks on a first side of the substrate in use; registration mark detection means associated with each of the first and at least one further station means for detecting at least one registration mark provided on the substrate in use, and control means for calculating a first alignment error of the at least one detected registration mark with respect to the first station means and for calculating at least one further alignment error of the at least one detected registration mark with respect to each of said further station means, characterised in that the control means are arranged to calculate a virtual alignment error for each of said further station means by taking the calculated alignment error at each of said further station means and comparing it relative to the first alignment error.
Thus, rather than only using a calculated alignment error of a detected registration mark with respect to the station means at which the error has been detected at to correct registration alignment of a printing and/or embossing process, the system of the present invention uses the calculated alignment error at a station means to calculate a new virtual alignment error that is related to the alignment error detected at a start of the process or at a first nominated/designated station means. This provides the present invention with all the advantages of a conventional back mark register or front mark register system but overcomes the problems associated with conventional back mark or front mark register systems. The present invention no longer requires the position of a registration mark to be accurate as the alignment error is calculated for each detected registration mark relative to the station means at the start of the process or a nominated/designated station means.
Preferably the station means are stations or points in an apparatus, such as for example and in-line apparatus, where a function, process and/or action of the apparatus is capable of being performed in used.
Preferably the one or more patterns or marks printed and/or embossed by the further station means can include any or any combination of one or more images, letters, numbers, symbols, shapes, patterns, marks, pictures and/or the like.
Preferably the first station means is a print station means (i.e. a station having a printing facility). However, it will be noted that the print station means may or may not be printing during use of the process. For example, the print station may have the facility to be able to print but not actually be printing during the process. In this latter arrangement the first station means simply acts to provide a tension to the substrate. In other examples, the first print station means can be providing a first ink pattern on the first side of the substrate in use.
In one embodiment the first station means can be an embossing station means (i.e. a station having an embossing facility). However, it will be noted that the embossing station means may or may not be embossing during use of the process. For example, the embossing station may have the facility to be able to emboss but not actually be embossing during the process. In this latter arrangement the first station means simply acts to provide a tension to the substrate. In other example, the first emboss station means can be providing a first emboss pattern on the first and/or a second side of the substrate in use.
Preferably the second side of the substrate is opposite to the first side of the substrate.
Preferably the at least one further station means can be any or any combination of a print station means or an emboss station means. Thus, the present invention could be a print registration system, an emboss registration system, or a print and emboss registration system.
In one embodiment the first station means and the further station means are all print station means, or all emboss station means.
In one embodiment the first station means and the further station means can be one of a number of different possible arrangements of print stations and/or emboss stations.
Thus, it will be appreciated that the present invention, in its broadest form, provides a registration system for allowing an alignment error of a registration mark to be calculated based on a first calculated alignment error, rather than solely on an alignment error of the registration m!ark at each station means of an apparatus.
In one embodiment the at least one registration mark is provided or located on the second side of the substrate in use. Preferably the at least one registration mark can be at least one printed registration mark and/or can be at least one non-printed registration mark, such as for example a feature or a repeated feature of the substrate material itself.
In one embodiment the at least one registration mark is provided or located on the first side of the substrate in use and can be at least one printed registration mark that is integrated into the main print design being provided or provided separate thereto and/or can be at least one non-printed registration mark, such as for example a feature or a repeated feature of the substrate material itself.
In one embodiment the registration system uses at least one registration mark provided on the first side of the substrate and at least one registration mark provided on a second side of the substrate.
In one embodiment the system includes pre-printing means which prints at least one registration mark on the first or front side of the substrate and/or second or rear side of the substrate prior to the substrate passing through the first station means in the process.
Preferably the system of the present invention is arranged such that unique identification means are provided with or associated with each registration mark provided or located on the first or front side of the substrate and/or second or rear side of the substrate. As such, each registration mark can be accurately tracked and identified throughout the entire process, thereby allowing a first alignment error to be calculated for each registration mark.
Preferably the unique identification means can be any or any combination of one or more bar codes, QR codes, numbers, letters, symbols, patterns, images and/or the like.
In one embodiment, in addition to or as an alternative to providing each registration mark with unique identification means, each registration mark can be identified by a calculation derived from the length of the substrate that has passed through the system or process up to the point of substrate length measuring means, and the length of the path between the first and further station means, or between a further station means and an adjacent further station means.
Preferably each registration mark is identified and/or is given its unique identification means on detection of the registration mark by the registration detection sensing means provided or associated with the first station means.
Preferably this same identification or identification mark is then retained by or associated with said registration mark as it passes through the remainder of the system (i.e. as it travels past the further printing means).
In one embodiment the substrate is in the form of an elongate continuous web of material.
In one embodiment the substrate is in the form of discrete or non-continuous webs of material.
Preferably the substrate consists, is formed from or includes any or any combination of paper, board, cardboard, plastic, plastic film, fabric, multi-layered material, laminate material and/or the like.
Preferably the pre-printing means that can be provided is different to the first and/or at least one further print station means that can be provided in the system.
Preferably the first and at least one further print station means ate of the same or similar type.
Preferably the pre-printing means is in the form of an ink jet printer, a flexo printer and/or the like.
Preferably the pre-printing means is a non-grip printing means in that tension is not applied to the substrate by said pre-printing means. However, the pre-printing means can be any printing device.
Preferably the first and/or at least one further station means is in the form of screen printing means or printer, a gravure printing means or printer and/or the like.
Preferably the first and at least one further station means includes tensioning means to provide a tension to the substrate.
Preferably the first and/or at least one further station means each include at least two rotatable and/or cylindrical printing and/or embossing members or rollers between which the substrate moves during a printing and/or embossing process.
Preferably the at least two rotatable and/or cylindrical printing and/or embossing members or rollers create a ‘grip’ or tension nip on the substrate as it passes through the same.
Preferably the first station means is run at a pre-determined and fixed speed.
Preferably the first station means, or one or more operational parameters of the first station means, is not corrected or controlled by the first calculated alignment error in use.
Preferably the first station means is run at a pre-determined and fixed speed set by an electronic line shaft generated as part of the system.
Preferably the control means are associated with the further station means and are synchronised, at least partially, to the electronic line shaft generated as part of the system.
Preferably the further station means ate run or controlled, or one or more operational parameters of the further station means are controlled, by using the virtual alignment errors calculated for each further station means.
In one embodiment each registration mark comprises or consists of a single mark.
In one embodiment each registration mark comprises or consists of two or more marks.
Preferably the at least one registration mark is arranged to visually or optically contrast with the substrate on which it is located in use so that the registration mark is clearly visible to the registration mark detection means. For example, the at least one registration mark can be printed in black or relatively dark ink so that it is clearly visible by the registration mark detection means on a white or light coloured substrate. Alternatively, a white or light coloured ink could be used to print the at least one registration mark so that it is clearly visible by the registration mark detection means on a black or dark coloured substrate.
The registration mark detection means can include any sensor or sensors that allow detection of a registration mark in use. For example, the registration mark detection means can be in the form of one or more contrast sensors.
In one embodiment the registration mark detection means is provided downstream of the station means with which it is associated in use.
In one embodiment separate control means are provided for each of the first and at least one further station means.
In one embodiment one control means are provided for two or more of the first and/or further station means.
Preferably the first and further alignment errors are calculated via the control means by comparing the position of the detected registration mark by a particular position registration detection means with the position of the station means that said particular position registration detection means is associated with in use.
Preferably the position of the station means is the position of one or more print and/or emboss cylinders or members forming said print and/or emboss station means, and further preferably is the angular position of the one or more print and/or emboss cylinders or members.
Preferably the system is used in an in-line printing and/or embossing apparatus, in that all the printing and/or embossing station means are provided in a single print and/or emboss line.
In one embodiment the virtual alignment error is calculated by taking the calculated alignment error at each of said further station means and subtracting the first alignment error calculated at the first station means.
Thus, in one embodiment, the calculation of the virtual alignment error (VAE) is:
VAE at station means cy’ = (alignment error at station means ‘y’) — (first alignment error at station means ‘x’);
Where x= the first, nominated or master station or station means of a printing and/or embossing apparatus; and y= the number of the second, further and/or slave station means downstream of station means ‘x’ in said printing and/or embossing apparatus.
Preferably the first, nominated or master station means is typically at the start of the process (i.e. the first non-registration mark working printing and/or embossing means).
Preferably the first side of the substrate is a front surface of the substrate, and the second side of the substrate is a tear surface of the substrate.
In one embodiment only the one or more registration marks are printed or provided on the second or rear side of the substrate.
Preferably the print and/or emboss design or pattern is printed on the first or front side of the substrate.
Preferably a different ink colour is associated with each of the first and further print station means in use. However, two or more different ink colours could be provided with one or more of the print station means if required.
Preferably memory means or data storage means are associated with the control means to allow at least the first alignment error to be stored therein in use.
In one embodiment one or more other printing and/or embossing accessories may be provided in the print and/or embossing line, print and/or embossing apparatus or printing and/or embossing process, such as for example, one or mote drying ovens, ink drying means and/or the like.
Preferably the printing and/or embossing station means referred to in this embodiment can be working or operational or non-working or inoperable for a particular printing and/or embossing process. For example, some printing means may be included in the print apparatus but are not working or operational as they are not required for a particular printing process, such as for example, the ink colour provided by said printing means is not required for a particular print pattern or design being printed by the apparatus, the ink has tun out and/or the like.
In one embodiment the control means, having calculated a virtual alignment error for a particular station means, can then use said virtual alignment error to control one or more parameters or operational parameters of said particular station means.
Preferably the control means includes micro-processing means, software, data storage means, data storage medium and/or the like.
Preferably the one or more parameters or operational parameters of said station means include any or any combination of the speed of the one or more print and/or emboss cylinders or members forming part of said station means, the position or angular position of the one or more print and/or emboss cylinders or members forming part of said station means and/or the like.
According to a one aspect of the present invention there is provided a print registration system, said system including pre-printing means arranged for printing at least one registration mark on a side of a substrate in use; a first printing means and at least one further printing means provided downstream of the first printing means and arranged for each printing one or more ink patterns on an opposite side of the substrate; registration mark detection means associated with each of the first and at least one further printing means for detecting the at least one registration mark, and control means for calculating a first akgnment error of the at least one detected registration mark with respect to the first printing means and for calculating further alignment errors of the at least one detected registration mark with respect to each of said further printing means, characterised in that the control means is arranged to calculate a virtual alignment error for each of said further printing means by taking the calculated alignment error at each of said further printing means and comparing it relative to the first alignment error or subtracting the first alignment error from said calculated alignment error.
According to one aspect of the present invention there is provided a method of using a registration system, said method including the steps of passing a substrate through a first station means and applying a tension to the same; passing the substrate through at least one further station means provided downstream of the first station means and printing and/or embossing one or more patterns or marks on a first side of the substrate; detecting at least one registration mark provided on the substrate using registration mark detection means associated with each of the first and at least one further station means; calculating a first alignment error of the at least one detected registration mark with respect to the first station means, and calculating at least on further alignment error of the at least one detected registration mark with respect to each of said further station means; characterised in that the method includes the step of calculating a virtual alignment error for each of said further station means by taking the calculated alignment error of each of said further station means and comparing it relative to the first alignment error.
According to a further aspect of the present invention there is provided apparatus including a registration system.
According to a further aspect of the present invention there is provided a method of using apparatus including a registration system.
Preferably the registration system is used with print and/or emboss apparatus.
According to one aspect of the present invention there is provided a computer readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the alignment error calculation steps described herein.
Thus, the present invention provides a virtual alignment error which, in effect, acts as a 'virtual front surface registration mark’ but without providing a physical mark on the substrate. Any of the front surface printing and/or embossing station means can generate the virtual alignment error. The present invention therefore provides an accurate, flexible and reliable registration system.
An embodiment of the present invention will now be described with reference to the following figures, wherein:
Figure 1 (PRIOR ART) is a simplified view of print apparatus incorporating a conventional back mark registration control system;
Figure 2 is a simplified view of print apparatus according to an embodiment of the present invention;
Figure 3a is a simplified view of the print apparatus in figure 2 with more detail shown; and
Figure 3b is an enlarged view of the circle in figure 3a.
Although the following embodiments refer exclusively to a print registration system for use with print apparatus, it will be appreciated that the principles of the registration system of the present invention could apply to printing and/or embossing apparatus.
Referring to figures 2-3b, there is illustrated a print registration system 100 for printing a three colour ink print pattern using an in-line print apparatus according to an embodiment of the present invention. As such, there are three main printing stations 8, 12, 14, in the apparatus, each printing station arranged for printing a different ink colour or colours of the print pattern onto a front surface of a substrate or web material 6. The components of system 100 that ate the same as the system 1 shown in figure 1 are referenced using the same reference numerals.
Registration marks 2 are printed at spaced apart intervals on a rear surface 4 of the substrate 6 by a pre-printer 10 in the form of an ink jet printer.
Each registration mark 2 is detected by registration mark detection sensor SI, S2, S3 located downstream of each printing station 8,12, 14 respectively.
Each control means 18 of system 100 generates an alignment error associated with each registration mark 2 as per the conventional back mark registration system 1, described with reference to figure 1. Thus, for example:
Registration marker detection sensor SI detects registration mark 2 and the control means 18 calculates an alignment error (Error 1) based on this mark 2 relative to the angular position of print roller 5 at the first print station 8.
Registration marker detection sensor S2 detects registration mark 2 and control means 18’ calculates an alignment error (Error 2) based on this mark 2 relative to the angular position of print roller 5’ at the second print station 12.
Registration marker detection sensor S3 detects registration mark 2 and control means 18” calculates an alignment error (Error 3) based on this mark 2 relative to the angular position of print roller 5” at the third print station 14.
Errors 1, 2 and 3 are what is known as ‘web-cylinder’ errors.
However, in contrast to the prior art back mark registration system, the present invention provides each registration mark with a unique identification code 22. In this example, the unique identification code is an integer number that increases in value by 1 for each new registration mark printed by registration mark printer 10, such as ‘29674’, ‘29675’ etc. However, it will be appreciated that the unique identification code could comprise anything that allows each registration mark printed by the system to be uniquely identified.
If we take an example of one particular registration mark that is labelled as ‘x’ by control means 18 and track it through the print process, the web-cylinder errors for this mark calculated at the first print station 8, the second print station 12 and the third print station 14 will be Error l(x), Error 2(x) and Error 3(x) respectively. These errors are stored by data storage means associated with the control means 18,18’and 18”.
Thus, as registration mark ‘x’ passes the first print station 8, it is detected by sensor SI, and an alignment error ‘Error l(x)’ is calculated by control means 18. Registration mark ‘x’ then moves towards the second print station 12. After a period of time after passing through print station 8, registration mark ‘x’ is detected by sensor S2 at print station 12 and an alignment error ‘Error 2(x)’ is calculated by control means 18’. After a further period of time after passing through print station 12, registration mark ‘x’ is detected by sensor S3 at print station 14 and an alignment ‘Error 3(x)’ is calculated by control means 18”.
This tracking system can be implemented for any pattern of back registration marks that might be used.
Each registration mark is typically printed on the rear surface of the substrate at a spaced apart interval from an adjacent registration mark, which is usually equal to or greater than 1% of the path length between repeated printed patterns on the front surface of the substrate. However, the minimum spaced interval between rear surface registration marks can be reduced by including additional rear surface registration marks, datum marks and/or the like.
Instead of the first print station 8 following the speed of the registration mark printer 10 as it does with a conventional back mark registration system, the first print station 8 runs at a pre-determined fixed speed taken from electronic line shaft 17, as shown by arrow 102, without any registration/alignment correction. The alignment Error l(x) for first print station 8 is then used as the reference point for all other print stations in the print system. Thus, first front surface print station 8 is acting as a “virtual key-mark registration station’. The control means 18 at the first print station 8 does not change any operational parameters relating to the print rollers 5, 7 in relation to Error l(x).
When the registration mark x is detected at print station 2 (12) by detection sensor
52, the control means 18’ takes the normal calculated alignment Error2(x) and subtracts Error 1 (x) away from the same to provide a virtual front mark error for print station 2.
Thus, virtual alignment error at print station 2 = Error2(x) — Errorl (x)
The calculated virtual alignment error at print station 2 is then used to control one or more parameters of the print rollers 5’, 7’ at print station 2, such as for example, adjust the speed of the print rollers, adjust the angular placement of the print rollers and/or the like so as to correct any misalignment detected.
When the registration mark x is detected at print station 3 (14) by detection sensor
53, the control means 18” takes the normal calculated alignment Error3(x) and subtracts Errorl (x) away from the same to provide a virtual front mark error for print station 3.
Thus, virtual alignment error at print station 3 = Error 3(x)- Errorl (x)
The calculated virtual alignment error at print station 3 is then used to control one or more parameters of the print rollers 5”, 7” at print station 3, such as for example, adjust the speed of the print rollers, adjust the angular placement of the print rollers and/or the like so as to correct any misalignment detected.
This process could be continued for any number of printing stations provided in the print system.
The present invention calculates the alignment error with respect to a virtual or master front surface printing station, typically the first working front surface printing station of the in-line printing process. Although the ‘virtual front mark error’ is calculated using a back surface registration mark, rather than using the ink pattern printed by the first working front surface printing station, it will be almost identical to the error measured if the key mark had been printed on the front surface of the substrate.
Thus, it can be seen that the present invention removes the problems associated with a conventional back mark registration system and improves the accuracy of the registration equivalent to that of a front mark registration system, such as a front mark web-web registration system or a front mark web-cylinder registration system. In contrast to the conventional back mark registration system, the accuracy of the registration system of the present invention is not determined by the registration accuracy of the back marks. As long as the registration marks are printed or located within pre-determined limits associated with the control means, the virtual alignment errors calculated will eliminate any printer alignment errors.

Claims (24)

Claims
1. A registration system, said system including first station means for applying a tension to a substrate passing through the same in use, and at least one further station means provided downstream of the first station means arranged for printing and/or embossing one or more patterns or marks on a first side of the substrate in use; registration mark detection means associated with each of the first and at least one further station means for detecting at least one registration mark provided on the substrate in use; and control means for calculating a first alignment error of the at least one detected registration mark with respect to the first station means, and for calculating at least on further alignment error of the at least one detected registration mark with respect to each of said further station means; characterised in that the control means are arranged to calculate a virtual alignment error for each of said further station means by taking the calculated alignment error of each of said further station means and comparing it relative to the first alignment error.
2. The registration system of claim 1, wherein the first station means is a print station means or an emboss station means.
3. The registration system of claim 1, wherein the system is arranged such that at least one registration mark is provided or located on the first side and/or a second side of the substrate in use.
4. The registration system of claim 1, wherein the system includes pre-printing means which is arranged to print at least one registration mark on the first and/or a second side of the substrate prior to the substrate passing through the first station means in use.
5. The registration system of claim 1, wherein the system is arranged so that unique identification means are provided with or associated with each registration mark provided or located on the first side and/or the second side of the substrate in use.
6. The registration system of claim 5, wherein the identification means is any or any combination of one or more bar codes, Quick Response (QR) codes, numbers, letters, patterns, symbols or images.
7. The registration system of claims 1 or 5, wherein in addition to, or as an alternative to providing each registration mark with unique identification means, the system is arranged such that each registration mark is identified using a calculation identification derived from the length of the substrate that has passed through the system up to the point of substrate length measuring means, and the length of the path between the first and further station means, or between a further station means and an adjacent station means.
8. The registration system of any one of the preceding claims, wherein each registration mark is identified or given a unique identification means on detection of the registration mark by the registration detection sensing means provided or associated with the first station means.
9. The registration system of any one of the preceding claims, wherein the substrate consists of, is formed from, or includes any or any combination of paper, board, cardboard, plastic, plastic film, fabric, multi-layered material or laminate material.
10. The registration system of claim 4, wherein the pre-printing means is a nongrip printing means.
11. The registration system of claim 4, wherein the pre-printing means is in the form of an ink jet printer or a flexo printer.
12. The registration system of claim 1, wherein the first station means and/or at least one further station means is in the form of a screen printing means or a gravure printing means.
13. The registration system of claim 1, wherein the first station means and the at least one further station means are provided with tensioning means to provide a tension to the substrate in use.
14. The registration system of claim 1, wherein the first and/or at least one further station means each include at least two rotatable and/or cylindrical printing and/or embossing members or rollers between which the substrate moves during a printing and/or embossing process in use.
15. The registration system of claim 1, wherein the first station means is run at a pre-determined and fixed speed in use, and is not corrected or controlled by the first calculated alignment error.
16. The registration system of claims 1 or 15, wherein the pre-determined and fixed speed is set by an electronic line shaft generated as part of the system.
17. The registration system of claims 1 or 16, wherein the control means are associated with the further station means and are synchronised, at least partially, to an electronic line shaft generated as part of the system.
18. The registration system of claim 1, wherein the further station means are run or controlled, or one or more operational parameters of the further station means are controlled, by using the virtual alignment errors calculated for each further station means.
19. The registration system of claim 1, wherein the registration detection means are provided downstream of the station means with which it is associated in use.
20. The registration system of claim 1, wherein the first and further alignment errors are calculated via the control means by comparing the position of the detected registration mark by a particular position registration detection means with the position or angular position of the station means that said particular position registration detection means is associated with in use.
21. The registration system of claim 1, wherein the system is an in-line printing and/or embossing apparatus.
22. The registration system of claim 1, wherein the virtual alignment error is calculated by taking the calculated alignment error at said further station means and subtracting the first alignment error calculated at the first station means.
23. The registration system of claim 1, wherein the control means, having calculated a virtual alignment error for a particular station means, is then arranged to use the virtual alignment error to control one or more parameters or operational parameters of the particular station means, the speed of one or more print and/or emboss cylinders or members forming part of the station means, and/or the position or angular position of one or more print and/or emboss cylinders or members forming part of the station means.
24. A method of using a registration system, said method including the steps of passing a substrate through a first station means and applying a tension to the same; passing the substrate through at least one further station means provided downstream of the first station means and printing and/or embossing one or more patterns or marks on a first side of the substrate; detecting at least one registration mark provided on the substrate using registration mark detection means associated with each of the first and at least one further station means; calculating a first alignment error of the at least one detected registration mark with respect to the first station means, and calculating at least on further alignment error of the at least one detected registration mark with respect to each of said further station means; characterised in that the method includes the step of calculating a virtual alignment error for each of said further station means by taking the calculated alignment error of each of said further station means and comparing it relative to the first alignment error.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020084648A1 (en) * 2000-12-28 2002-07-04 Robert Pierce Accurate registration for imaging
US20090265950A1 (en) * 2008-04-23 2009-10-29 Xerox Corporation Registration system for a web printer
JP2016215494A (en) * 2015-05-20 2016-12-22 大日本印刷株式会社 Printer and printing method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020084648A1 (en) * 2000-12-28 2002-07-04 Robert Pierce Accurate registration for imaging
US20090265950A1 (en) * 2008-04-23 2009-10-29 Xerox Corporation Registration system for a web printer
JP2016215494A (en) * 2015-05-20 2016-12-22 大日本印刷株式会社 Printer and printing method

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