EP1980516B1 - Method and device for determining the position of webs of material - Google Patents

Description

The invention relates to a device and a method for determining the position of webs or strands in printing machines. The machine is preferably a web-fed rotary printing press, preferably for offset printing, in particular wet offset. It may be a commercial press, or more preferably a large-format newspaper press.

In a printing machine, lateral displacements of a material web can occur before, during and after the convergence of the strands into bundles of strands. Possible reasons for this are paper quality, changes in speed, web tension and web stretching, register adjustments, mechanical alignment of the paper guide elements, paper paths, deflections, etc. The displacements occur mainly in areas where the strands or bundles are not clamped and guided.

After the fan, the individual strands are brought together on the hopper collecting and -einlaufwalze so that they come to lie one above the other. In some systems, the longitudinal section of the material web can only take place on the hopper collecting and infeed roller. In many systems, the longitudinal section takes place before the turning module.

Above the funnel to the next steering roller and / or tension roller, the strand bundle is not performed. For broadsheet products, the bundles are weakly guided by the forming fold on the funnel. For tabloid products, the web guide is rotated 90 degrees above the funnel without creating a longitudinal fold. Therefore, individual strands in the strand bundle can shift laterally, especially in the case of tabloid products. Shifts of the strands above the funnels in the bundles of strands are particularly troublesome in tabloid products with so-called false panorama. Strand displacements are possible in principle from the formation of the strands by the longitudinal section of the material web to the finished product.

In the prior art systems for determining the lateral position and position of the printed image to the cross section and longitudinal section of a web have long been known. Such systems require special marks or use the printed image to determine the lateral position of the printed image on the web and the position of the printed image for product cutting in the folder. For the determination of the lateral position of a material web and sensors are used, which are adapted to detect the web edges.

However, the measuring and detection techniques used in known systems can only detect the position of a material web. The detection methods are at most capable of detecting more than one material web in one plane. The multi-lane is achieved by the sensor is movably mounted and can be moved. However, not more than one track or strand can be detected and measured simultaneously with a prior art measuring device.

The sensors and their traverse or positioning unit also need space. This space requirement is decisive for the installation location of the sensors.

The measuring locations are chosen so that the sensors are arranged close to the positioning units and are placed where the accessibility to each material web is guaranteed. An early measurement and detection of the material web position can lead to material web displacements, which can occur later, no longer be detected and therefore can not be corrected automatically.

In the EP 1 521 715 B1 a measuring device for detecting a material web is described. The sensor is movable parallel to the material web level and is provided after the turning module for each material web guide. The layers of the webs are measured individually in front of the hopper before the webs come to rest on each other.

In the EP 0 850 763 B1 describes a system for detecting the position and quality of a printed image on a web, which by means of optical means color marks absorbs on the material web. For each side of a material web a sensor is needed.

WO 2004/007325 A discloses a device for measuring a layer of material webs, wherein sensors mounted on guide rolls can be displaced over the length of the guide rolls.

Out EP 0 987 205 A1 a loop buffer for a material web is known in which a sensor device is provided for detecting the storage filling.

• eine Vorrichtung und ein Verfahren bereitzustellen, um die Lage von einzelnen aufeinander oder übereinander liegenden Materialbahnen zu erfassen,
• eine Vorrichtung und ein Verfahren zur Korrektur von erfassten Verschiebungen bereitzustellen.

It is an object of the invention

• to provide a device and a method for detecting the position of individual superimposed or superimposed webs of material,
• to provide an apparatus and method for correcting detected shifts.

At least one of these objects is achieved by a method according to claim 1 or an apparatus according to claim 29. The subordinate claims define preferred embodiments of the invention.

For detecting superimposed webs according to the present invention, an optical or a capacitive measuring system can be used.

The Messvonichtung can serve to detect web material layers and in particular lateral layers of webs. The material webs can be in surface contact with other webs at the measuring location. The material webs can run in different planes. The material webs can also be guided very tightly over one another at the measurement location, so that they can partially touch one another. It is also conceivable that widely spaced webs of material can be detected simultaneously with the same measuring method. In another embodiment, however, the material webs to be detected can also run at least partially in the same planes.

In the case of the measuring device according to the invention, a single measuring unit can detect the position of at least two strands of material. However, it is also conceivable that a certain number of strands of material through several measuring units whose number is less than that of the material strands. It is thus possible, for example, for the positions of three material webs to be detected by two measuring units, likewise for detecting 4, 5, 6,..., Web material positives by 3, 4, 5,... N-1 measuring units or even conceivable by even fewer measuring units. A measuring unit may further comprise one or more sensors.

The measuring device according to the invention can use one-, two- and / or three-dimensional measuring techniques. Such measuring techniques are known and used in the geometry testing of objects. Known techniques for geometry testing are based on the basic principle of triangulation, such as the light-section method, areal structured illumination and photogrammetry. For example, point, line or area triangulation methods can be used.

The measuring system can, for example, use the light-section method based on the triangulation principle. Here, a fan-shaped laser beam (line projector) is projected onto the measurement object, whereby a sharp light-dark line is generated on the object surface, the course of which can be recorded by a camera and automatically evaluated with special algorithms.

The triangulation which can be used for example in the present invention is an active method and uses a light source, usually a laser, which illuminates the material webs which are to be measured. An electronic image converter, usually a CCD or CMOS camera or a PSD, registers the scattered light. With knowledge of the beam direction and the distance between camera and light source, the distance from the object to the camera can be determined. The connection camera light source and the two beams from and to the object form a triangle, hence the term triangulation. If the process is carried out in a grid-like or continuously moving manner, the surface relief can be determined with great accuracy, with commercially available sensors up to 0.01 mm. When projecting a pattern, for example a line or a striped pattern, the distance information for all points of the pattern can be calculated with a single camera image. In a line, one also speaks of light section, striped patterns are used in the strip projection.

The advantages resulting from the strand edge detection according to the invention also include the possibility that edges in a strand bundle, ie where several strands come to rest on one another, can be measured. Also, a later measurement than in known systems is possible and therefore a later and sustainable correction and influencing the lateral strand position possible. There are also fewer sensors or measuring systems as required in the prior art to perform the measurements. It is also possible to track relationships and dependencies with regard to web tension and the cutting position.

For example, laser, LED or LCD grid projectors can serve as light sources for a lighting unit of the measuring device. The light used can be projected onto the object to be measured in a punctiform and / or linear manner and / or in the form of a specific pattern. The light sources can be operated permanently or pulsating. The reflected light can be detected, for example, by CCD, CMOS, PMD sensors or photodiodes. One or more sensors and / or one or more light sources may be used per measurement and / or measuring device,

However, two-dimensional measuring methods from image processing without triangulation methods, such as, for example, image recording with subsequent edge extraction, are also conceivable as measuring methods in the present invention.

In an optical measuring method, it may happen that individual material web edges are covered by other overlying material webs. Therefore, one or a plurality of measuring devices and / or measurements may be provided for the present task. A measuring device can detect a profile of a bundle edge and / or two profiles of a bundle side. In another embodiment, it is possible to detect with a measuring device front and back of a material bundle edge. In a further embodiment, all four strand bundle profiles can be detected with a measuring device. The detection of two strand bundle edges of adjacent bundles is also conceivable.

The measuring unit can be permanently mounted on a machine element or movably positionable. The measuring unit can be used in conjunction with a kinematic motion detection system to locate the exact measuring device position.

In order to simplify the detection of the edges, the flat bundles can be bent slightly, in particular to ensure the accurate detection of thin material web layers, of which under certain circumstances only fractions of a millimeter are visible at the bundle edge. The bending of the bundles ensures that the individual material web edges are better visible in the bundle. The bending of the bundles can for example be done mechanically by baffles or by an air flow. The bending of the bundle is conceivable at any point of the material web and can for example already take place above the funnel,

A simultaneous and synchronized recording of multiple material bundle edges by the measuring device is possible, wherein a speed matched scanning of the material webs for the detection of dynamic processes is advantageous.

By suitable marking in the vicinity of the bundle guide, it is possible to realize an absolute position detection of the individual strand edges in the bundle with respect to a fixed or moved machine element. The marking can be two or three-dimensional. The marker can also be attached near the strand or bundle center and / or edge. However, since the absolute position of the strand edges in the bundle with respect to the coordinate system of the detection unit is determined by the measuring method, a marking is not necessarily required.

Also conceivable are measuring devices in which the detection unit is in a fixed geometric relationship to the illumination unit and also measuring devices in which the detection unit and / or illumination unit are positionable in position or changeable in their position or orientation. By an optical monitoring of the strand edges, it is also possible to make a statement with regard to the condition of the paper cutting knives for the longitudinal cut.

With the measuring method according to the invention, the paper web thickness can also be determined. Conversely, from the planning and production data, the paper thickness and / or grammage can be used to improve the measurement, the measurement method can provide information about the position of the individual material webs to each other.

In order to distinguish the paper edges better, the front-side spraying or printing the paper rolls with certain patterns is conceivable. As a result, for example, the outer strand edges can be identified directly and unambiguously by the measuring device, whereby the marking can be invisible to the human eye, for example by using infrared markings, UV markings or the like. The markings or marks applied to at least one of the end faces of the paper roll can be detected and / or decoded by machine elements.

The material webs and in particular the paper rolls can be of different widths due to manufacturing tolerances and can easily change their width during processing (fan in / out). Different strands in their width can lead to other narrower strands or strand edges always remaining covered and hidden for optical measurement.

In order to avoid such problems, means may be provided to determine the width and position of the web before and after the longitudinal cut. By way of example, as possible measuring locations, the roll cell, roll changer, before and after the roll bonding, before or after the printing units, before or after the turning module and any arbitrary point in the course of the printing process or its preparation are conceivable and / or also to the material web on the cutting device and / or align the cutting device on the material web. The information obtained can also be used to align the strands with the funnel or to align the funnels with the strands.

To accurately determine the location and width of a web of material, fixed or movable sensors can be provided which detect the paper web edge, the printed image, or certain printed marks. The sensors can be moved manually or automatically in at least one coordinate direction. Due to the at least two-fold position detection on the lateral edges of a material web, the width of the material web can be determined,

The detected print image position can be used to influence the print position laterally as well as in the longitudinal direction of the cut.

In one embodiment, the obtained deviations or measured values via line layers can be used to influence or regulate the strand guide and thus the position of the material web. Suitable elements for this purpose are, for example, adjustable eccentric rollers, parallelograms, turner bars, paper roll edges or similar devices.

Webs that are stretched too weak tend to run restlessly. Overstretched webs tend to shrink and have a different behavior. Incorrectly tensioned strands can adversely affect the course of underneath and overlying strands in the bundle. It can therefore be provided to make the measurement results available to a web tension controller. Since the web tension can influence the cross-section in the folder, the measurement results can be fed to a cutting position controller.

If the print image position of the strands is detected, the information can be made available to the printing units to set the appropriate print image position. The images and / or measured values acquired by the measuring device can be used to visualize the strands or bundles. Conversely, measured values from other recording and measuring devices can be used to influence the measurement or regulation of the material webs.

Sensors are available, in particular CDD cameras from, for example, Sick, which can simultaneously detect a light section and an image of the object. In this special case, therefore, the edge measurement can take place simultaneously with the image acquisition. A visualization of the measured strand edge and bundle is real-time possible. With a normal CCD, this functionality can also be realized, although probably not timely, but sequentially,

Decisive for the wrong panorama is the position of the paper web and the position of the printed image on the paper. The consideration of the position of the printed image has already been mentioned and taken into account. Preferably, the measuring device additionally determines the lateral position of the printed image per strand.

For this purpose, images of converging paper webs, preferably between trays and funnel collection and infeed roller, are recorded with the same measuring device. The measuring device is aligned so that the strand edges are measured reliably and the edge of the type area of each strand is visible on a recorded image.

The evaluation of the image position on the paper web takes place image-based or without image data by means of printed stamps or brandless. Image data based without marks and branded with or without image data provide absolute reference locations and can be evaluated directly, In the case of a brand-less measurement without image data can eg by Plausibiltätsprüfung, Fuzyfizierung the decision, multiple detection, etc. and by adaptive and / or knowledge-based systems of the printed image.
In this way, it is possible to dispense with upstream systems.

Figur 1

ein Bündel zu vier Strängen in einer ersten Anordnung und schematisch die daraus resultierenden Messergebnisse,

Figur 2

ein Bündel zu vier Strängen in einer zweiten Anordnung und schematisch die daraus resultierenden Messergebnisse,

Figur 3

ein Bündel zu vier Strängen in einer dritten Anordnung und schematisch die daraus resultierenden Messergebnisse,

Figur 4

ein Bündel zu vier Strängen in einer vierten Anordnung und schematisch die daraus resultierenden Messergebnisse, wobei die Strangkanten flächenmäßig vermessen werden,

Figur 5

schematisch den von einer Messvorrichtung ausgehenden Datenstrom, schematisch neben der Messvorrichtung weitere gemessene Größen und die dadurch beeinflussten Größen, und die beeinflussbaren Einrichtungen bzw. Größen,

Figur 6

durch Pfeile angegebene beispielhafte Messorte bei der vorliegenden Erfindung.

The present invention will be explained in more detail with reference to the following figures. It may include features described individually and in any meaningful combination. Showing:

FIG. 1

a bundle of four strands in a first arrangement and schematically the resulting measurement results,

FIG. 2

a bundle of four strands in a second arrangement and schematically the resulting measurement results,

FIG. 3

a bundle of four strands in a third arrangement and schematically the resulting measurement results,

FIG. 4

a bundle of four strands in a fourth arrangement and schematically the resulting measurement results, wherein the strand edges are measured in terms of area,

FIG. 5

2 shows schematically the data flow originating from a measuring device, schematically further measured variables and the variables influenced thereby in addition to the measuring device, and the influenceable devices or variables,

FIG. 6

exemplary measurement locations indicated by arrows in the present invention.

X0 puts in the FIGS. 1 to 4 the desired position of all strands (S), which move in the direction of the arrow (R), in relation to any coordinate system. In the figures listed, a bundle consisting of four strands (S) is shown in each case. The horizontal line (B) transverse to the strands shows in the FIGS. 1 to 3 the place of measurement.

The two thin vertical lines show the set position X0 (A) of the strands on the one hand and the visual separation (D) of the left edge and right edge of a strand bundle side for the two-sided evaluation of the measurement. On both sides of the bundle, the result of the measurement (C) is shown schematically as a measuring profile. The numbers in the measurement profile correspond to the numbers of the strand edges in the image. The measurement profiles on both sides of the figures can be assembled into a profile as would be provided by a single measuring device for one bundle side and two bundle edges.

In FIG. 3 It can be seen that a strand (edge 4) is not initially detected by the selected viewing direction on one side. The problem can be remedied by further measuring devices on the opposite bundle side and / or by successive and / or recursive correction of the strand layers of the visible strands.

1. 1. Verschieben von Kante 1 auf Position X0
2. 2. Verschieben von Kante 2 auf Position X0
3. 3. Verschieben von Kante 3 auf Position X0
4. 4. Verschieben des zuvor verdeckten Stranges so, dass Kante 4 auf Position X0 zu liegen kommt.

By way of example, a method for error correction of the situation in FIG. 3 in which the bundle edges are viewed from only one side of the bundle.

1. 1. Move from edge 1 to position X0
2. 2. Move from edge 2 to position X0
3. 3. Move from edge 3 to position X0
4. 4. Move the previously hidden strand so that edge 4 comes to rest on position X0.

In FIG. 4 is shown schematically the areal registration of the strand edges. By detecting the edges over a certain width or at a plurality of locations, the angle or slope of the strands (S) relative to other strands (S) or absolutely relative to any coordinate system can be determined.

In the FIG. 6 various possible positions 5 for the measuring device are shown. These can be arranged both in the area of a collecting roller 3 or an inlet roller 4, or only after a broadsheet 1 or one or more tabloid products 2 have been brought together or brought together.

Claims (50)

1. A measuring method for detecting the position of material strands and/or webs in printing machines, characterised in that the positions of n material strands and/or webs which lie one on top of the other or one above the other are detected, transverse to their transport direction, by n-1 or fewer detection units.
2. The measuring method according to the preceding claim, characterised in that the positions of at least two material strands and/or webs are detected by a single detection unit.
3. The measuring method according to any one of the preceding claims, characterised in that detection is performed in a fixed geometric relationship to an illuminating unit which illuminates the material strands and/or webs.
4. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are respectively detected on at least one of their lateral edges.
5. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are respectively detected at at least two points which are spaced from each other in and/or transverse to the transport direction, preferably on one of their lateral edges.
6. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are respectively detected at at least two points which are spaced from each other transverse to the transport direction, preferably on both lateral edges.
7. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are respectively detected at an angle between the vertical and the horizontal with respect to the web plane.
8. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are respectively detected on both flat sides, preferably on both lateral edges, from above and below the material strand and/or web plane.
9. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are respectively detected over an area, preferably over an area from above and below the material strand and/or web plane.
10. The measuring method according to any one of the preceding claims, characterised in that at least one of the following methods is used as the measuring method:

    - a one-dimensional or two-dimensional optical measuring method;

    - a two-dimensional or three-dimensional measuring method;

    - a triangulation method;

    - a light-section method;

    - a method using area-structured illumination;

    - a method using photogrammetry.
11. The measuring method according to any one of the preceding claims, characterised in that the ascertained positions and/or deviations of the material strands and/or webs are used to determine the absolute position of the material strands and/or webs in an arbitrary coordinate system and/or the position relative to other material strands and/or webs, and preferably to automatically regulate and/or correct and more preferably successively and/or recursively correct the positions of the material strands and/or webs.
12. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs are bent transverse to the transport direction before the measuring position.
13. The measuring method according to any one of the preceding claims, characterised in that the ascertained strand and/or web positions are corrected simultaneously.
14. The measuring method according to any one of the preceding claims, characterised in that the bundle edges of the material strands and/or webs are reversed before the measuring position.
15. The measuring method according to any one of the preceding claims, characterised in that the material webs of a bundle of strands contact each other at least partially at a measuring position, preferably over an area.
16. The measuring method according to any one of the preceding claims, characterised in that the measurement results and images are fed to a web tension regulator, a cutting register regulator and/or a visualising unit or are used to assess the condition of cutting knives.
17. The measuring method according to the preceding claim, characterised in that the web and/or strand position is detected and evaluated on the basis of the web and/or strand edges and/or the image position is detected and evaluated on the basis of images or marks before and after cutting performed by the cutting knives.
18. The measuring method according to any one of the preceding claims, characterised in that the detection unit detects markings on the material strands and/or webs, preferably in the middle region and/or edge region of the material strands and/or webs.
19. The measuring method according to any one of the preceding claims, characterised in that machine elements detect and/or decode marks applied to the front-facing sides of the paper reels.
20. The measuring method according to any one of the preceding claims, characterised in that by identifying and determining the material strands and/or webs and the production and planning data, the corresponding paper path from a reel carrier via printing units, turning modules, registers, channelling elements and funnels up to the folding cut can be determined.
21. The measuring method according to any one of the preceding claims, characterised in that the material strands and/or webs and/or bundles are influenced in their lateral position by means of parallelograms, eccentric rollers, turning bars or similar components.
22. The measuring method according to any one of the preceding claims, characterised in that the material strand and/or web thickness is determined and/or the material strand and/or web thickness from the production data is used to detect the material strands and/or webs.
23. The measuring method according to any one of the preceding claims, characterised in that in order to measure the positions in the fan, material strands and/or webs which do not run in parallel planes are measured.
24. The measuring method according to any one of the preceding claims, characterised in that at least some of the material strands and/or webs which converge on one of the two channelling elements and contact each other over an area are supported by a first channelling element and guided by a second channelling element.
25. The measuring method according to any one of the preceding claims, characterised in that the positions of the material strands and/or webs are measured between the fan and the turning or register modules.
26. The measuring method according to any one of the preceding claims, characterised in that an edge measurement, preferably a light-section method, and image detection, preferably optical object image detection, are simultaneously performed by the at least one detection unit.
27. The measuring method according to any one of the preceding claims, characterised in that the detection unit detects both the position - preferably, the lateral position - of the material strands and/or webs and the position - preferably, the lateral position transverse to the transport direction - of a printed image on at least one material strand and/or web.
28. The measuring method according to any one of the preceding claims, characterised in that the position of the printed image on the material strand and/or web is directly evaluated on the basis of image data, by means of marks printed on it and/or without marks, preferably on the basis of reference positions.
29. A measuring device for detecting the position of material strands and/or webs in printing machines, characterised in that n-1 or fewer detection units of the device detect the positions of n material strands and/or webs which lie one on top of the other or one above the other, transverse to their transport direction.
30. The measuring device according to the preceding claim, characterised in that a single detection unit detects the positions of at least two material strands and/or webs, transverse to their transport direction.
31. The measuring device according to any one of the preceding claims, characterised in that a detection unit comprises at least two sensors and/or measuring devices.
32. The measuring device according to any one of the preceding claims, characterised in that a detection unit is arranged in a fixed geometric relationship to an illuminating unit which illuminates the material strands and/or webs.
33. The measuring device according to any one of the preceding claims, characterised in that the detection unit respectively detects the material strands and/or webs at at least one point, preferably one of their lateral edges.
34. The measuring device according to any one of the preceding claims, characterised in that at least one detection unit respectively detects the material strands and/or webs respectively at at least two points which are spaced from each other in and/or transverse to the transport direction, preferably on one of their lateral edges.
35. The measuring device according to any one of the preceding claims, characterised in that at least one detection unit respectively detects the material strands and/or webs respectively at at least two points which are spaced from each other transverse to the transport direction, preferably on both lateral edges.
36. The measuring device according to any one of the preceding claims, characterised in that the detection unit respectively detects the material strands and/or webs at an angle between the vertical and the horizontal with respect to the web plane.
37. The measuring device according to any one of the preceding claims, characterised in that at least one detection unit respectively detects the material strands and/or webs respectively on both flat sides, preferably on both lateral edges, from above and below the material strand and/or web plane.
38. The measuring device according to any one of the preceding claims, characterised in that at least one detection unit respectively detects the material strands and/or webs respectively over an area, preferably over an area from above and below the material strand and/or web plane.
39. The measuring device according to any one of the preceding claims, characterised in that it comprises at least one of the following devices as the measuring device:

    - a measuring device for one-dimensional or two-dimensional optical measuring;

    - a measuring device for two-dimensional or three-dimensional measuring;

    - a measuring device for triangulation measuring;

    - a measuring device for light-section measuring;

    - a measuring device using area-structured illumination;

    - a measuring device for photogrammetry.
40. The measuring device according to any one of the preceding claims, characterised in that the at least one detection unit comprises one or a combination of several of the following parts:

    - a CCD;

    - a CMOS;

    - a photo-cell array;

    - PDA sensors;

    - area sensors;

    - line sensors.
41. The measuring device according to any one of the preceding claims, further comprising at least one illuminating unit which comprises one or a combination of several of the following light sources:

    - a light source which is a thermal emitter;

    - a light source which is not a thermal emitter;

    - a laser projector;

    - a light projector;

    - an LCD projector.
42. The measuring device according to any one of the preceding claims, characterised in that a web tension regulator, a cutting register regulator and/or a visualising unit assesses the condition of cutting knives.
43. The measuring device according to any one of the preceding claims, characterised in that the material strands and/or webs are bent transverse to the transport direction before the measuring position.
44. The measuring device according to any one of the preceding claims, characterised in that it comprises parallelograms, eccentric rollers, turning bars or similar components using which material strands and/or webs and/or bundles are influenced in their lateral position.
45. The measuring device according to any one of the preceding claims, characterised in that in order to measure the positions in the fan, the material strands and/or webs to be measured do not run in parallel planes.
46. The measuring device according to any one of the preceding claims, characterised in that at least some of the material strands and/or webs, which are supported by a first channelling element and guided by a second channelling element, converge on one of the two channelling elements and contact each other over an area.
47. The measuring device according to any one of the preceding claims, characterised in that the detection unit detects markings of the material strands and/or webs, preferably in the middle region and/or edge region of the material strands and/or webs.
48. The measuring device according to any one of the preceding claims, characterised in that the at least one detection unit simultaneously performs an edge measurement, preferably a light-section method, and image detection, preferably optical object image detection.
49. The measuring device according to any one of the preceding claims, characterised in that the detection unit detects both the position - preferably, the lateral position - of the material strands and/or webs and the position - preferably, the lateral position transverse to the transport direction - of a printed image on at least one material strand and/or web.
50. The measuring device according to any one of the preceding claims, characterised in that the detection unit detects images or marks printed on the material strand and/or web in order to evaluate the position of the printed image on the basis of image data.

Images