EP2746054B1 - Method and device for printing containers - Google Patents

Description

The invention relates to a device and a corresponding method for printing on containers, in particular for the seamless all-round printing of bottles with a predetermined print template.

STATE OF THE ART

Currently, containers such as e.g. Plastic containers, especially bottles of polyethylene terephthalate (PET), provided in the food or pharmaceutical industry for labeling predominantly with labels that are attached by means of labeling or labeling on the container. However, the conventional labeling methods have a number of disadvantages associated with the separate manufacture and handling of the labels.

Alternatively, methods are known in which the containers are printed directly. Such a method is for example from the DE 35 26 769 A1 in which a stationary ink jet printhead is used to decorate a container rotating about its longitudinal axis. The preparation of a separate label and the attachment of the label on the container can thus be omitted.

However, both traditional container labeling and direct printing can experience problems if the containers have different dimensions. Even small deviations, for example, in the diameter of the containers can lead to clearly visible impairments if the containers are to be printed seamlessly along their circumference. Depending on whether the container has an upward or downward diverging diameter The conventional direct printing method either leads to a gap or to an overlap area in the printed decoration.

From the EP 2 054 232 B1 Thus, there is known a printing method capable of printing rotationally symmetric containers along its circumference, compensating for any variations in the length of the circumference by providing the artwork with angle marks used to control the relative rotational movement between the container and the printhead become. This ensures that the artwork can be imaged circumferentially seamlessly and without overlap to a full revolution of 0 ° -360 °. The disadvantage here, however, that it can lead to a distorted representation of the artwork and / or that the artwork can indeed be printed seamlessly in the circumferential direction, but it can lead to differences in the height of the printed image.

A similar procedure is from the DE 10 2009 033 810 A1 It is also known that the printhead is controlled so as to maintain a constant distance from the container to be printed, even if it does not have a circular cross-section.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to specify an improved printing device or an improved printing method with which a printing original can be printed accurately on a plurality of different containers, in particular on slightly different containers, the differences being dependent only on production fluctuations.

This object is solved by the features of the independent claims. Preferred developments are the subject of the dependent claims.

It is the particular approach of the present invention to individually measure each of the containers to be printed in order to determine a scaling factor with which the (2-dimensional) master is scaled uniformly, ie while maintaining its aspect ratio, so that it is at least one direction (eg in the circumferential direction) coincides with the (in other words curved in three dimensions) pressure range of the container, in the other dimensions (eg in height) but is greater than the pressure range. In a second step, the print template scaled in this way is trimmed so that it also coincides with the specified print area in the other dimensions. This ensures that the print area specified on the container is seamlessly and completely printed without distorting the printed image.

According to a first aspect of the present invention, an apparatus for printing a plurality of containers with a digital artwork is provided. The apparatus comprises a surveying device adapted to determine at least two independent dimensions of a printing area of each container of the plurality of containers to be printed, and a control unit adapted to display, for each container to be printed, the at least two independent dimensions of the printing area receive from the surveying device to determine a scaling factor based on the received dimensions and dimensions of the print template, uniformly scale the print template with the determined scaling factor, wherein the scaling factor is selected so that the scaled print template in at least one measure with a corresponding measure the print area is equal to and in all other dimensions greater than the corresponding dimensions of the print area, and to crop the scaled artwork so that the cropped and scaled artwork is fully matched to the appropriate dimensions of the print area eichs coincides. The apparatus also includes a printing device configured to print the container with the cropped and scaled artwork.

According to a second aspect of the present invention there is provided a method of printing a plurality of containers with a digital artwork. The method comprises the steps of determining at least two independent measures of a printing area of each container of the plurality of containers to be printed; determining a scaling factor based on the determined dimensions and dimensions of the artwork; uniformly scaling the artwork with the determined scaling factor, wherein the scaling factor is selected such that the scaled artwork conforms, in at least one measure, to a corresponding measure of the printing area and is greater than the corresponding measures of the printing area in all other dimensions; crop the scaled artwork so that the cropped and scaled artwork matches in all dimensions with the appropriate measures of the printable area; and print the container with the cropped and scaled artwork.

In a preferred embodiment, a cut-off area is provided in an edge region of the print original, and the control unit is set up so that the print copy is cut only within the cut-off area. In this way, it can be ensured that no significant image information that can be contained in the print template is lost when cropping the print template. Essential image information may include, for example, details of the best before date, the ingredients, etc.

In a preferred embodiment, the artwork includes a prioritized image area, and the controller is further configured to move the prioritized image area within the artwork such that the artwork is cropped only outside or at the edge of the shifted, prioritized image area. Preferably, the control unit is further configured to shift the prioritized image area within the artwork such that an edge of the displaced prioritized image area coincides with an edge of the scaled and cropped artwork. In this way too, it can be ensured that no essential image information, which may be contained in the prioritized image area of the print original, is lost when the print original is cropped. In addition, it is ensured that this image information is always output at a predetermined location, in particular at the edge or at a predetermined distance therefrom, the cropped print template.

In another preferred embodiment, the artwork includes a reserved image area, and the controller is further configured to insert image information of a predetermined size into the reserved image area of the scaled artwork or the scaled and cropped artwork. In this way it can be ensured that the predetermined size of this image information is maintained during printing.

In a preferred embodiment, the measuring device has a scanning unit, which is set up to mechanically or optically scan the container to be printed. The scanning can also be performed from several sides, for example, from the side of a container and additionally from above, depending on the perspective from which the area of the container to be printed can be better recognized. The scanning can also be done only from the side or only from above. The printing device may in particular comprise an inkjet printhead.

For cylindrical containers or containers with a cylindrical section, the pressure area may be substantially rectangular. The at least two independent dimensions of the printing area then preferably indicate the height and width of the printing area. One of the at least two independent dimensions of the printing area may preferably correspond to a circumference of the container to be printed.

In a preferred embodiment, the digital artwork is in a computer-readable graphics format, especially in a pixel-oriented or a vector-oriented graphics format.

The area to be printed can be determined by three-dimensional shapes of a container, for example via grooves, grooves, protrusions and the like on the outer surface of the container.

In particular, it is contemplated to perform a multi-color printing with multiple printheads, which are preferably arranged in different modules. Each (electronically controllable) printhead is connected to the control unit. Instead of the arrangement in different modules, the print heads can also be arranged in a machine.

The information about the length and width passed on to the different print heads are the same in particular for all print heads, but may also differ in exceptional cases, namely if a print copy in an edge area contains no elements which require a specific color.

Fig. 1

schematisch einen Behälter mit einem zu bedruckenden Bereich zeigt,

Figs. 2A und B

Beispiele zeigen für die Anwendung eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung,

Figs. 3A und B

Beispiele zeigen für die Anwendung eines Verfahrens gemäß weiterer Ausführungsformen der vorliegenden Erfindung,

Fig. 4

ein Beispiel zeigt für die Anwendung eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung für eine nicht rechteckige Druckvorlage, und

Fig. 5

schematisch den Aufbau einer erfindungsgemäßen Vorrichtung für das nahtlose Bedrucken von Behältern mit leicht variierenden Maßen zeigt.

The invention will be described below with reference to the accompanying drawings, wherein

Fig. 1

schematically shows a container with an area to be printed,

Figs. 2A and B

Examples show for the application of a method according to an embodiment of the present invention,

Figs. 3A and B

Examples show for the application of a method according to further embodiments of the present invention,

Fig. 4

an example shows for the application of a method according to an embodiment of the present invention for a non rectangular printing master, and

Fig. 5

schematically shows the structure of a device according to the invention for the seamless printing of containers with slightly varying dimensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 schematically shows a container, such as a PET bottle, with a region to be printed 12. In the illustrated example, the area to be printed 12 is substantially cylindrical and has a height H and a diameter D. The area 12 is to be seamlessly and completely printed with a substantially rectangular print template. The print template would have to have a height and a width corresponding to the height H and the circumference U. For containers with a circular cross-section, the circumference of the diameter is known to be U = π D; with a different shape of the cross-section, there are corresponding relationships. However, due to unavoidable manufacturing tolerances, both the height and the diameter (circumference) of the containers vary independently. Even if the original can be scaled in one direction (eg, in the circumferential direction) to compensate for these variations, it can not be guaranteed that the print area in the other direction (eg, the height) will be completely printed without causing any distortion in the print image comes.

It has now been recognized that this problem can be solved by first measuring each of the containers to be printed to determine at least two independent dimensions of the printing area (e.g., width and height). In a second step, a scaling factor is determined so that the print template uniformly scaled with this scaling factor matches exactly the print area (eg the correct height) in at least one of the determined dimensions, but the scaled print copy is in all other dimensions (eg the width ) is greater than the pressure range. The remaining discrepancy is corrected in the third step by cropping the scaled artwork accordingly. In the example, the width of the scaled artwork is thus shortened accordingly, so that it coincides with that of the predetermined width of the print area.

Alternatively, it would also be possible to scale the artwork in the first step so that the scaled artwork in (to the specified extent) is smaller than the print area and the remaining margin with a fill color, a fill image, or a copy of the adjacent one Cover print template area.

The inventive method is in Figs. 2A and 2B shown schematically.

In Fig. 2A a print original 15 is first uniformly, ie, while maintaining its aspect ratio, reduced, until the height of the print template coincides with the predetermined height H of the printing area. Then, the width of the scaled artwork is cropped so that the width of the scaled and cropped artwork also matches the specified width of the printable area. The cut off area of the artwork is shown in the figure by the narrow hatching.

Fig. 2B largely corresponds to the method of Fig. 2A However, here the artwork is designed so that it must be trimmed generally in height and not in width. Accordingly, the print original 15 is first uniformly reduced until the width of the print original coincides with the predetermined width B of the print area. The height of the scaled and cropped artwork is then adjusted to the height of the printable area. The cut off area of the artwork is again indicated in the figure by the narrow hatching.

In a preferred embodiment, the artwork has an edge region 16 (in FIG Figs. 2A and 2B represented by the wide hatching), which is particularly suitable for pruning. In particular, this edge region should not contain any significant image information. Optionally, the artwork in this border area can also be designed so that it can connect seamlessly to the opposite edge of the artwork regardless of the cropping. In particular, the printing original in this edge region can have a uniform coloring or a coloring which does not vary, at least in the direction perpendicular to the cutting edge.

An advantageous development of the method according to the invention is in Figs. 3A and 3B shown schematically. In this development, the print template has a prioritized image area 17 that contains image information that is not to be changed by the clipping process. The prioritized image area 17 is shifted to within the print template so that the artwork is cropped only outside or at the edge of the shifted priority image area. In particular, the prioritized image area 17 within the artwork may be shifted such that an edge of the shifted prioritized image area coincides with an edge of the scaled and cropped artwork. The prioritized image area can be scaled like the rest of the artwork (as in Figs. 3A and 3B shown), or from the Scaling, that is, maintaining its original size. It is also possible to set conditions in the control system where the prioritized area must not be deferred. This is advantageous if certain (preferably middle) regions of the printing original 15 are not to be covered by the prioritized region 17.

In a further advantageous embodiment, the printing area may contain a reserved image area 18 into which image information having a predetermined size is inserted. The paste can be made in the reserved image area of the scaled artwork or the scaled and cropped artwork, so that the specified size is preserved during printing.

The present invention is not related to Figs. 1 to 3 limited rectangular printing areas and templates, but can be applied to arbitrarily shaped printing areas or templates. In addition, the invention is not limited to pressure ranges characterized by two independent dimensions (such as length and width) but may also be used for containers whose pressure ranges are defined by a greater number of independent measures.

It is also possible to take into account structures present on the container surface, such as hot-fill pannels, grooves, elevations, threads or the like, in such a way that specific areas, points or lines of the printing original are permanently assigned to these structures in their position. In this case, the inventive scaling and cropping of the artwork can also be limited to subregions of the artwork. For example, if four rectangular images (in the artwork, they are lined up) are to be applied to a square cross-section bottle, each side of the bottle can be separately captured and each of the four sub-images of the artwork be adjusted separately with the method according to the invention such that each partial image extends exactly to the corners of the square.

Also, artwork may have different resolutions in certain areas, especially in the structures mentioned. Here is also thought to change the resolution according to the measured data in the sub-areas relative to the other areas. If a rib in the blowing process is less pronounced, for example because of a too low blowing pressure, the elevation of the rib from a bottle base coat is not as high as at high blowing pressure. An originally higher resolution for the surfaces which emerge from the base coat can then be chosen correspondingly lower. For an overall smaller bottle, where this rib is also smaller, the resolution can be provided as a kind of "third dimension" with the same scaling factor as the height and width.

Fig. 4 schematically shows an example of a non-rectangular print template (dotted line), as may be required for example for printing a conical portion of a container. The corresponding pressure range (solid line) can be characterized by three independent dimensions, eg by the in Fig. 4 given radius R, the width B and the angle φ. These dimensions are determined by a corresponding measurement of the container to be printed. The print original 15 can be uniformly scaled in a first step (in this case scaled down), wherein the scaling factor is selected such that the radius of the scaled print original agrees with the corresponding dimension R of the print area, but the scaled print original matches in all other dimensions (B and φ) is greater than the pressure range. The uniform scaling preserves the aspect ratio of the original, ie the original is scaled in the x-direction and in the y-direction with the same factor. In the second step, the artwork can be trimmed to match the pressure range for the other two dimensions B and φ.

In the example shown, two areas are affected by the crop, which are characterized by the narrow hatching.

Fig. 5 shows schematically the construction of an apparatus according to the invention for the seamless printing of containers with slightly varying dimensions.

The device comprises a holder for the containers 10 to be printed with a bottle plate 22 and a so-called tulip 21, with which the containers are centered and held clamped against the bottle plate. The bottle plate and the tulip are rotatably mounted and can be rotated by a motor drive 23 angle true.

The device further comprises a printer device with a print head 35, which can be displaced vertically and optionally radially and / or tilted via a corresponding holder 30. The printer device may operate on the ink-jet principle or any other suitable method.

The device also includes a measuring device 40 for geometric measurement of the container, with which the dimensions of the printing area 12 can be determined. The measurement is preferably carried out optically, wherein the measuring device may comprise, for example, a laser 41 and a corresponding spatially resolving detector 42. However, the measurement can also be done mechanically with suitable scanning elements or in another suitable manner.

The apparatus further comprises a control unit 50, which is adapted to receive the results of the measuring device 40, to process the original document according to the method described above, to control the printer device 30, 35 and to coordinate with the drive 23.

A similar process can also be used in the traditional labeling with label material by the labels are cut to the appropriate size shortly before their application to the container by means of a laser or with a quick-adjustable knife.

The containers are preferably disposable PET bottles. But it can also be equipped other containers such as cans, glass bottles and the like.

Adjustment of the artwork is not only required when manufacturing tolerances of the containers occur, but also when two containers of different types are to be equipped. For example, on the one hand, 0.5-liter coke bottles and 1.5-liter coke bottles could be printed with the same artwork, even one after the other in a single production run.

Claims (11)

1. Device for printing a plurality of containers with a digital print template, comprising:

   a measurement device (40) adapted to determine at least two independent dimensions of a print area (12) of each container (10) to be printed of the plurality of containers;

   a control unit (50) adapted

   to receive, for each container (10) to be printed, the at least two independent dimensions of the print area (12) from the measurement device (40),

   to determine a scaling factor on the basis of the received dimensions and of dimensions of the print template (15),

   characterized by a control unit which scales the print template (15) uniformly with the determined scaling factor,

   wherein the scaling factor is selected such that the scaled print template corresponds in at least one dimension to a corresponding dimension of the print area (12) and is larger in all other dimensions than the corresponding dimensions of the print area (12), and

   trimming the scaled print template such that the trimmed and scaled print template corresponds in all dimensions to the corresponding dimensions of the print area (12); and

   a printing device (30) adapted to print the container (10) with the trimmed and scaled print template.
2. Device according to claim 1, wherein a cut-off region is provided in an edge region of the print template (15) and the control unit (50) is adapted such that the print template is trimmed only within the cut-off region.
3. Device according to claim 1 or 2, wherein the print template (15) comprises a prioritized image area and the control unit (50) is further adapted to shift the prioritized image area within the print template such that the print template is trimmed only outside or at the edge of the shifted prioritized image area.
4. Device according to claim 3, wherein the control unit (50) is further adapted to shift the prioritized image area within the print template such that an edge of the shifted prioritized image area coincides with an edge of the scaled and trimmed print template.
5. Device according to any one of claims 1 to 4, wherein the print template (15) comprises a reserved image area and the control unit (50) is further adapted to insert image information of a predetermined size into the reserved image area of the scaled print template or the scaled and trimmed print template so that the predetermined size is retained during printing.
6. Device according to any one of claims 1 to 5, wherein the measurement device (40) comprises a scanning unit (41, 42) adapted to scan the container (10) to be printed mechanically or optically.
7. Device according to any one of claims 1 to 6, wherein the printing device (30) comprises an ink jet printhead (35).
8. Device according to any one of claims 1 to 7, wherein the at least two independent dimensions of the print area (12) indicate the height and width of the print area (12).
9. Device according to any one of claims 1 to 8, wherein one of the at least two independent dimensions of the print area (12) corresponds to a circumference of the container (10) to be printed.
10. Device according to any one of claims 1 to 9, wherein the digital print template is present in a computer-readable graphics format, in particular in a pixel-oriented or a vector-oriented graphics format.
11. Method for printing a plurality of containers with a digital print template, wherein
    at least two independent dimensions of a print area (12) of each container (10) to be printed of the plurality of containers are determined;
    a scaling factor is determined on the basis of the determined dimensions and of dimensions of the print template;
    the print template is uniformly scaled with the determined scaling factor, wherein the scaling factor is selected such that the scaled print template corresponds in at least one dimension to a corresponding dimension of the print area (12), characterized in that the print template is larger in all other dimensions than the corresponding dimensions of the print area (12);
    the scaled print template is trimmed so that the trimmed and scaled print template corresponds in all dimensions to the corresponding dimensions of the print area (12); and the container (10) is printed with the trimmed and scaled print template.

Images