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Title:
REGISTER MARK
Document Type and Number:
WIPO Patent Application WO/2004/030911
Kind Code:
A1
Abstract:
A web provided with a register mark (200), the register mark (200) comprising a first line set (201, 204) and a second line set (202,203), each line set comprising two parallel lines, the first line set (201,204) being perpendicular to a web direction and the second line set (202,203) being oblique to the web direction. Also, a method is presented for producing a register mark (200), in which the register mark (200) is relief printed in the same production stage as a crease lining of a web material.

Inventors:
NORENSTAM RICKARD (SE)
IDBERG MAGNUS (SE)
EK LEIF (SE)
BRISEGAARD MATS (SE)
Application Number:
PCT/SE2003/001487
Publication Date:
April 15, 2004
Filing Date:
September 24, 2003
Export Citation:
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Assignee:
TETRA LAVAL HOLDINGS & FINANCE (CH)
NORENSTAM RICKARD (SE)
IDBERG MAGNUS (SE)
EK LEIF (SE)
BRISEGAARD MATS (SE)
International Classes:
B41F33/00; B65H23/04; B65H39/00; (IPC1-7): B41F33/00; B65H23/00; B26D5/32; B65B41/08
Domestic Patent References:
WO1995025941A11995-09-28
Foreign References:
US2802666A1957-08-13
US3701464A1972-10-31
EP0131241A21985-01-16
US4135664A1979-01-23
DE1049480B
US4690051A1987-09-01
Attorney, Agent or Firm:
Sundell, HÃ¥kan (Central Patent Department Ruben Rausings gata, Lund, SE)
Download PDF:
Claims:
CLAIMS
1. 1 Web provided with register mark (200), characterised in that the register mark (200) comprises a first line set 201,204 and a second line set (202,203), each line set comprising at least two parallel lines, the first line set (201,204) being perpendicular to an intended direction of travel for the web, and the second line set (202,203) being oblique to the web direction.
2. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 010 degrees from the lines 201,204 included in the first line set.
3. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 1020 degrees from the lines (201,204) included in the first line set.
4. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 2030 degrees from the lines (201,204) included in the first line set.
5. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 3040 degrees from the lines (201,204) included in the first line set.
6. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 4050 degrees from the lines (201,204) included in the first line set.
7. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 5060 degrees from the lines (201,204) included in the first line set.
8. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 6070 degrees from the lines (201,204) included in the first line set.
9. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 7080 degrees from the lines (201,204) included in the first line set.
10. Web provided with register mark (200) according to claim 1, characterised in that the second line set (202,203) is arranged with an angle (a) of 8090 degrees from the lines (201,204) included in the first line set.
11. Web provided with register mark (200) according to any of the preceding claims, characterised in that the second line set (202,203) is arranged between the lines (201,204) included in the first line set.
12. Web provided with register mark (200) according to any of the preceding claims, characterised in that the register mark (200) is in relief form.
13. Web provided with register mark (200) according to any of the preceding claims, characterised in that the register mark (200) is used for positioning of a packaging material web.
14. Web provided with register mark (200) according to any of the preceding claims, characterised in that the register mark (200) is used for positioning of packaging material webs in packaging machines.
15. Web provided with register mark (200) according to any of the preceding claims, characterised in that the relief mark is coexisting with printed prior art register marks.
16. Method for producing a web material provided with a register mark (200), characterised in that the register mark (200) is provided to the web material in the same production stage as a fold lining of the web material.
17. Method according to claim 16, characterised in that the provision of the register mark to the web material is made by extra embossments or grooves in fold lining rolls for the fold lining of the web material, leading to a relief register mark.
18. Method according to any of the claims 16 or 17, characterised in that the web material comprise packaging material for production of packages.
Description:
TITLE OF THE INVENTION REGISTER MARK TECHNICAL FIELD The present invention relates generally to a register mark for webs, and more specifically to a register mark for webs containing material for packaging machines. The invention also includes a method for providing the register mark to the web.

PRIOR ART EP 0131 241 Bl. describes a device and a method for using printed optical register marks for longitudinal positioning of a material web in a packaging machine. The register marks are a combination of two printed line sets perpendicular to an intended direction for the web, which line sets are read by an optical reading device.

EP 0131 241 B1 is mainly related to positioning of material webs in packaging machines, for manufacturing packages. Those packages are manufactured in a way well known by a person skilled in the art. In short, the packaging material is formed into a tube by heatsealing two longitudinal edges of the packaging material towards one another. After the forming of the tube, the product to be packaged (often pourable food products like wine, juices or dairy products) are poured into the tube, after which the tube is heat-sealed.

The result from the above stages is a row of "pillows"of packaging material filled with food product.

After the heat sealing, the pillow row is cut to pieces, each piece comprising a single pillow.

The folding of the pillow into a finished package takes place after the cutting of the pillow row. If the pillow position is wrong with respect to fold lines

arranged to facilitate the folding of the pillow portion into a finished package, the folding of the pillow will be less perfect, compared to what would be the case if the pillow-position was correct with respect to the fold lines.

The register marks primary purpose is to give information to the packaging machine about the packages longitudinal position relative to the web. This information is used to synchronise different operations, like hole punching splice and tube sealing. Having fold lines pressed into the material on appropriate positions facilitates the folding of the pillows to finished products (packages).

One major problem with the prior art solution is that the printing of the optical register marks and the provision of relief fold lines are performed in separate manufacturing stages. This leads to register tolerance in positioning-of the fold lines vs. the printed, optical marks, which in turn leads to an less perfect product, since the positioning of the"pillows"is controlled by the location of the printed register mark, and not by the location of the fold lines.

Further, the design of the optical register mark, with lines perpendicular to the web direction only, make it impossible to determine the lateral position of the web.

Lateral mispositioning also leads to less accuracy of the location of the fold lines vs. the actual folding, mainly longitudinal folding.

As is well understood by persons skilled in the art, the fold lines are pressed in the packaging material by some kind of pressing device. The main purpose of the fold lines is to facilitate folding of the packaging material by weakening the material. This can be done in a lot of ways, e. g. cutting or creasing of the packaging material. The preferred method is however to crease the packaging material between crease rolls provided with intrusions and protrusions in accordance with the desired fold line

pattern. As can be understood, it is very easy to provide further intrusions/protrusions to the crease rolls to provide a relief mark to the packaging material during the fold lining process.

SUMMARY OF THE INVENTION The present invention solves the above and other problems by providing a register mark comprising a first line set and a second line set, each line set comprising two parallel lines, the first line set being perpendicular to a web direction and the second line set being oblique to the web direction.

Further, the register mark is preferably of relief type. Hence, the register marks can readily be provided to the packaging material in the same production stage as the fold lines are provided to the packaging material, which minimises the risk for mispositioning of register mark/fold lines.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a schematic view showing a preferred embodiment of the register mark according to the present invention.

Figure 2 is a schematic view showing an alternative embodiment of the register mark according to the present invention.

Figure 3 is a schematic view showing a preferred embodiment for a coincidence method used to read the register marks.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference to figure 1, a register mark 200 according to the invention consists of two line sets, one perpendicular line set (lines 201 and 204) and one oblique line set (lines 202 and 203). Both line sets consists of at least two parallel lines 201,204 and 202,203, respectively. The angle between the two line sets is denoted with a.

In figure 2 an alternative embodiment for the lines 201-204 constituting the register mark is shown. In this embodiment, it is possible to have equal distances between the lines constituting each line set, which can be advantageous in some cases. The angle between the two line sets is here also denoted with a.

The reading of the different line sets, and a device to perform the reading of the lines are described in a co- pending patent application, but for clarification the reading method will be described hereinafter.

With reference to fig. 3, at TO, the register mark 200 on the material web is approaching the detector areas D1-D4 on a detector (not shown). Only a first detector area D1 reads a signal from the line 204, meaning that the signal is treated as a misreading.

At T1, a detector area D2 gets signal from the line 203. Since D3 does not simultaneously gets a signal, the signal from D2 is regarded as a misread.

At T2, both detector areas D1 and D4 gets signal from the perpendicular line set 201,204, which leads the detector system to regard the reading as being a reading of a correct longitudinal position of the web.

At T3, both detector areas D2 and D3 detect signal from the oblique lines 202,203, leading the system to regard the reading as a correct reading for the lateral position of the web.

At T4 and T5, only single detector area readings occur, leading the system to regard the readings as misreads.

If the web is perfectly laterally aligned, the reading of the two perpendicular lines 201,204 by detector areas D1 and D4 and the reading of the two oblique lines 202,203 by detector areas D2 and D3 will coincide in time, or have a predetermined time separation.

The reason behind the coincidence demand for the readings of each line set is that single perpendicular and oblique lines might be contained in the design printing or the fold lining of the package material. If there was no coincidence demand for the line set readings, such lines could be regarded as lines included in the register mark.

The dimensions of the register mark must however be chosen with great care: the distance between the line sets must be chosen so that no other types of lines (like fold lines or design lines) are separated the same distance as the line sets of the register mark, since such lines otherwise could be misread as lines constituting the register mark.

As can be understood from the above, the angle a is important for the function of the register mark. A high value of the angle a gives a high accuracy for the lateral positioning, but requires a larger register mark. A lower value of the angle a gives a lower accuracy, but admits the use of a mark with smaller dimensions. The overall dimensions of the mark are finally determined by space restrictions, fold line distances and the demand for lateral accuracy. Further, the largest lateral mispositioning of the mark also determines the final size of the register mark. If the web for some reason would get so much laterally mispositioned that the register mark is not readable for the reading device, the system is prohibited from making correct lateral adjustments of the web. This could be of course be avoided by providing a

larger register mark, but other restrictions for the size, such as package size, should also be considered when the size of the register mark is decided.

One important feature with the register mark according to the present invention is that it could be of relief type. Relief register marking of a packaging material that include fold lines is fairly simple, since the fold lining process readily could be adapted to include the provision of a relief register mark. The inclusion of the relief register marking in the fold lining process can be accomplished e. g. by providing extra embossments or grooves in the fold lining rolls, in a way that is easily comprehended by a person skilled in the art.

By including the provision of the register mark in the same production stage as the fold lining, the risk of misalignment or mispositioning of fold lines vs. register marks is minimised.

It is worth to notice, that the method described above is not limited to reading of relief register marks; in some cases, it might be useful to use the method to read printed, optical marks.

One very important feature with the present invention is that it readily could co-exist with prior art devices for reading optical marks of the obsolete type.




 
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