阅读说明：本技术 用于包装的密封部分的质量评估的方法及其装置 (Method for quality assessment of sealed portion of package and apparatus therefor ) 是由 马格纳斯·拉贝 汉斯·哈尔斯坦迪斯 维克托·彼得松 丹尼尔·祖卢莫夫斯基 霍坎·安德松 斯 于 2019-10-21 设计创作，主要内容包括：一种用于对包装(100)的密封部分(414)进行质量评估的方法(1600),其中,所述包装(100)包括至少稳固性层(406a,406b)和塑料层(408a,408b)。密封部分(414)是通过以下方式而形成的：保持所述包装(100)的第一部分(402a)和第二部分(402b)彼此抵靠,同时提供热量,使得所述第一部分和第二部分(402a,402b)的塑料层(408a,408b)熔化,从而使得所述第一部分和第二部分(402a,402b)彼此粘附。方法(1600)包括：使用相机(814)捕获(1602)描述所述密封部分(414)的图像数据,识别(1604)所述图像数据中的参考线(1204,1304,1404,1504),识别(1606)所述图像数据中的密封部分边界线(1202,1302,1402,1502),基于所述参考线(1204,1304,1404,1504)和所述密封部分边界线(1202,1302,1402,1502)确定(1608)密封部分评估特征集,以及比较(1610)所述密封部分评估特征集与参考特征集。(A method (1600) for quality assessment of a sealed portion (414) of a package (100), wherein the package (100) comprises at least a stability layer (406a, 406b) and a plastic layer (408a, 408 b). The sealing portion (414) is formed by: holding a first portion (402a) and a second portion (402b) of the package (100) against each other while providing heat such that the plastic layers (408a, 408b) of the first and second portions (402a, 402b) melt, thereby causing the first and second portions (402a, 402b) to adhere to each other. The method (1600) comprises: capturing (1602) image data describing the sealed portion (414) using a camera (814), identifying (1604) a reference line (1204, 1304, 1404, 1504) in the image data, identifying (1606) a sealed portion boundary line (1202, 1302, 1402, 1502) in the image data, determining (1608) a sealed portion evaluation feature set based on the reference line (1204, 1304, 1404, 1504) and the sealed portion boundary line (1202, 1302, 1402, 1502), and comparing (1610) the sealed portion evaluation feature set to a reference feature set.)

1. A method (1600) for quality assessment of a sealed portion (414) of a package (100), wherein the package (100) comprises at least a stability layer (406a, 406b) and a plastic layer (408a, 408b), wherein the sealed portion (414) is formed by: holding a first portion (402a) and a second portion (402b) of the package (100) against each other while providing heat such that plastic layers (408a, 408b) of the first and second portions (402a, 402b) melt, thereby adhering the first and second portions (402a, 402b) to each other, the method (1600) comprising:

capturing (1602) image data describing the sealed portion (414) using a camera (814),

identifying (1604) reference lines (1204, 1304, 1404, 1504) in the image data,

identifying (1606) a seal portion boundary line (1202, 1302, 1402, 1502) in the image data,

determining (1608) a set of sealing portion evaluation features based on the reference line (1204, 1304, 1404, 1504) and the sealing portion boundary line (1202, 1302, 1402, 1502), and

comparing (1610) the seal portion evaluation feature set to a reference feature set.

2. The method of claim 1, wherein the seal section assessment feature set includes at least one distance measure between the reference line (1204, 1404, 1504) and the seal section boundary line (1202, 1302, 1402, 1502).

3. The method of any one of the preceding claims, further comprising:

determining (1612) a seal section evaluation area (1206) defined by the reference line (1204) and the seal section boundary line (1202),

wherein the seal section evaluation feature set comprises the seal section evaluation region (1206).

4. The method of any one of the preceding claims, further comprising:

determining (1614) a boundary line deviation measure by comparing the seal portion boundary line (1302) to an ideal seal portion boundary line (1306),

wherein the at least one seal segment evaluation feature set comprises the first boundary line deviation measure.

5. The method of any one of the preceding claims, further comprising:

determining (1616) a reference-line deviation metric by comparing the reference line (1504) to an ideal reference line (1512),

wherein the seal section evaluation feature set comprises the reference line deviation measure.

6. The method of any one of the preceding claims, further comprising:

identifying (1618) a peripheral non-sealing portion (1410) having an open end facing the sealing portion boundary line (1408),

determining (1620) a depth of the peripheral non-sealing portion (1410) by determining a minimum distance between the peripheral non-sealing portion (1410) and the reference line (1404),

wherein the at least one sealing portion evaluation feature set comprises a depth of the peripheral non-sealing portion (1410).

7. The method of any one of the preceding claims, further comprising:

identifying (1622) an interior non-sealing portion (1510) in the sealing portion (414),

determining (1624) an area of the inner unsealed portion (1510),

wherein the sealing portion evaluation feature set includes the region of the inner non-sealing portion (1510).

8. The method of any of the preceding claims, wherein the sealing portion evaluation feature set further comprises input sealing energy.

9. The method according to any of the preceding claims, wherein the reference line (1204, 1304, 1404, 1504) depicts a ridge-embossed portion of the sealing portion (414).

10. The method according to any one of claims 1 to 8, wherein the reference line (1204, 1304, 1404, 1504) depicts a cut line.

11. A device (800) for quality assessment of a sealed portion (414) of a package (100), wherein the package (100) comprises at least a stability layer (406a, 406b) and a plastic layer (408a, 408b), wherein the sealed portion (414) is formed by: holding a first portion (402a) and a second portion (402b) of the package (100) against each other while providing heat such that plastic layers (408a, 408b) of the first and second portions (402a, 402b) melt, thereby causing the first and second portions (402a, 402b) to adhere to each other, the apparatus (800) comprising:

a camera (816) configured to capture image data depicting the sealed portion (414),

a processing device (818) configured to identify a reference line (1204, 1304, 1404, 1504) in the image data, wherein the reference line (1204, 1304, 1404, 1504) depicts a ridge-stamped portion of the seal portion (414); identifying a seal portion boundary line (1202, 1302, 1402, 1502) in the image data; determining a seal portion evaluation feature set based on the reference line (1204, 1304, 1404, 1504) and the seal portion boundary line (1202, 1302, 1402, 1502); and comparing the seal portion evaluation feature set to the reference feature set.

12. The apparatus of claim 8, wherein the seal section assessment feature set includes at least one distance measure between the reference line (1204, 1304, 1404, 1504) and the seal section boundary line (1202, 1302, 1402, 1502).

13. The apparatus of any one of claims 11 or 12, wherein the reference line (1204, 1304, 1404, 1504) depicts a ridge-stamped portion of the sealing portion (414).

14. The apparatus according to any one of claims 8 or 9, wherein the processing device (818) is further configured to determine a seal portion evaluation area (1206) defined by the reference line (1204, 1304, 1404, 1504) and the seal portion boundary line (1202, 1302, 1402, 1502), wherein the seal portion evaluation feature set includes the seal portion evaluation area (1206).

15. A computer program product comprising instructions which, when executed on a computer, cause the computer to perform the method of any one of claims 1 to 10.

Technical Field

The present application relates generally to the field of packaging. And more particularly to quality assessment of sealed portions, such as in packaging for food products.

Background

Paperboard packaging for milk and other food products is well known and appreciated in many parts of the world. One example is the brick-shaped packaging Tetra Pak (Tetra Brik) sold by Tetra Pak^TM). Such packages are produced in machines known as reel packaging machines. The general principle of this type of machine is to form a tube of packaging material, fill the tube with the food product, and form the packages from the lower end of the tube. Since these steps are carried out continuously, the advantage is that speeds of 30000 packages per hour or even more can be achieved. Another type of machine for producing packages of food products is the so-called blank-type packagingA machine is provided. In this type of machine, the packaging material is provided in the form of blanks (i.e. sleeve-like and pre-cut sheets of packaging material), which are filled one by one to form the packages.

In both types of packaging machines, for each package, a top and a bottom are formed by sealing together two portions of packaging material. Today, different sealing techniques (also called welding techniques) can be used. For packaging materials comprising an aluminium layer, induction heat sealing techniques can be used. The general principle of this technique is to induce an electric current in the packaging material, thereby generating heat. The heat in turn melts the outer plastic layers in the packaging material so that they can adhere to each other while being held against each other. Another example of a sealing technique that may be used is ultrasonic sealing. This technique generates heat not by inducing current, but by using ultrasonic waves.

Regardless of the sealing technique used, the sealed portion is formed in the package. These seals ensure that the package does not leak and, particularly for aseptic packages, unwanted microorganisms cannot enter the package. Today, there are different methods to assess the quality of the sealing portion. A straightforward approach is to have the operator regularly inspect the produced packages to detect deviations that may be caused by insufficient tightness. One example of an indirect method for detecting insufficient tightness is to close the package while applying pressure to the side, thereby forming an inwardly protruding side portion in the package. If the sealing portion is insufficient, air will leak into the package, causing the side portions to no longer bulge inwardly. Thereby, a package which may have an insufficient sealing portion can be easily found.

Even though there are now direct and indirect methods for detecting seal insufficiency in packages, there is still a need for improvements to further reduce the time and effort required to identify packages with seal insufficiency.

Disclosure of Invention

It is an object of the present invention to at least partially overcome one or more of the above-mentioned limitations of the prior art. In particular, it is an object of the present invention to provide a device and a method which enable an easy and cost-effective identification of an insufficient sealing portion.

According to a first aspect, a method for quality assessment of a sealed portion of a package is provided, wherein the package comprises at least a stability layer and a plastic layer, wherein the sealed portion is formed by: holding the first and second portions of the package against each other while providing heat such that the plastic layers of the first and second portions melt, thereby causing the first and second portions to adhere to each other, the method comprising: capturing image data describing the seal portion using a camera, identifying a reference line in the image data, identifying a seal portion boundary line in the image data, determining a seal portion evaluation feature set based on the reference line and the seal portion boundary line, and comparing the seal portion evaluation feature set to the reference feature set.

The seal portion evaluation feature set may include at least one distance measure (measure) between the reference line and the seal portion boundary line.

The method may further comprise: determining a seal portion evaluation area defined by the reference line and the seal portion boundary line (1202), wherein the seal portion evaluation feature set includes the seal portion evaluation area.

The method may further comprise: determining a boundary line deviation measure by comparing the seal portion boundary line to an ideal seal portion boundary line, wherein the at least one seal segment evaluation feature set comprises the first boundary line deviation measure.

The method may further comprise: determining a reference line deviation measure by comparing the reference line to an ideal reference line, wherein the seal section evaluation feature set includes the reference line deviation measure.

The method may further comprise: identifying a peripheral non-sealing portion having an open end facing the sealing portion boundary line, determining a depth of the peripheral non-sealing portion by determining a minimum distance between the peripheral non-sealing portion and the reference line, wherein the at least one sealing portion evaluation feature set includes the depth of the peripheral non-sealing portion.

The method may further comprise: identifying an inner non-sealing portion among the sealing portions, determining an area of the inner non-sealing portion, wherein the sealing portion evaluation feature set includes the area of the inner non-sealing portion.

The seal portion evaluation feature set may also include input sealing energy.

The reference line may depict a ridge-embossed portion of the sealing portion.

Alternatively, the reference line may depict a cut line.

According to a second aspect, there is provided an apparatus for quality assessment of a sealed portion of a package, wherein the package comprises at least a stability layer and a plastic layer, wherein the sealed portion is formed by: holding the first and second portions of the package against each other while providing heat such that the plastic layers of the first and second portions melt, thereby causing the first and second portions to adhere to each other, the apparatus comprising: a camera configured to capture image data depicting the sealed portion, a processing device configured to identify a reference line in the image data, wherein the reference line depicts a ridge-stamped portion of the sealed portion; identifying a seal portion boundary line in the image data; determining a seal portion evaluation feature set based on the reference line and the seal portion boundary line; and comparing the seal portion evaluation feature set to the reference feature set.

The seal portion evaluation feature set may include at least one distance measure between the reference line and the seal portion boundary line.

The reference line may depict a ridge-embossed portion of the sealing portion.

The processing device may be further configured to determine a seal section evaluation zone defined by the reference line and the seal section boundary line, wherein the seal section evaluation feature set includes the seal section evaluation zone.

According to a third aspect, there is provided a computer program product comprising instructions which, when executed on a computer, cause the computer to perform the method according to the second aspect. The step of capturing the image data may be a step of reading the image data from an image sensor such as a CMOS or a CCD. Alternatively, it may receive image data from a camera external to the device executing the computer program.

Other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

Drawings

Embodiments will now be described, by way of example, with reference to the accompanying schematic drawings in which,

FIG. 1a is a perspective view of a package;

FIG. 1b generally illustrates a packaging material that may be formed into the package shown in FIG. 1 a;

figure 2 shows a reel-type packaging machine in general;

FIG. 3 is a cross-sectional view of an exemplary packaging material;

FIG. 4 generally illustrates a lower portion of the package shown in FIG. 1 a;

FIG. 5 shows an example of a cross-sectional view of a sealing portion;

FIG. 6 shows another example of a cross-sectional view of a sealing portion;

FIG. 7 shows an example of a front view of a sealing portion;

8a-c show by way of example an arrangement for quality assessment of a seal portion;

figures 9a and 9b show two further examples of the device in general;

FIG. 10 illustrates, by way of example, one embodiment of the apparatus;

11a-b show another embodiment by way of example;

FIG. 12 is an example of a cross-sectional view of a seal portion;

FIG. 13 is another example of a cross-sectional view of a sealing portion;

FIG. 14 is yet another example of a cross-sectional view of a sealing portion;

FIG. 15 is yet another example of a cross-sectional view of a sealing portion;

fig. 16 is a flowchart showing the steps of the evaluation method of the quality of the sealed portion.

Detailed Description

Fig. 1a generally shows an example of a cardboard package 100 made from the sheet of packaging material shown in fig. 1 b. The paperboard package 100 includes a plurality of panels separated from one another by lines of weakness. The lines of weakness enable a sheet of packaging material to be reliably and efficiently folded into a package 100 by a packaging machine (also referred to as a filling machine).

In this example, the package 100 comprises a first back panel 102, a left panel 104, a front panel 106, a right panel 108 and a second back panel 110, which together form a sleeve-like body of the package 100. The first rear panel 102 and the second rear panel 110 are attached to each other by a longitudinal seal. In order to avoid that the product contained in the package comes into contact with the inner layer of the packaging material, the peripheral edge portion of the second back panel 110, which peripheral edge portion of the second back panel 110 is located inside the peripheral edge portion of the first back panel 102, may be protected by a plastic strip (also called longitudinal sealing strip).

In addition, the package 100 also includes a first top back panel 112, a left corner top panel 114, a top front panel 116, a right corner panel 118, and a second top back panel 120 that together form the top of the package 100. In a similar manner to the first and second back panels 102, 110, the first and second top back panels 112, 120 are attached to each other. To enclose the package 100, the first and second top back panels 112, 120 are each attached with the top front panel 116, two portions of the left corner top panel 114 are attached to each other, and two portions of the right corner top panel 118 are also attached to each other. This is achieved by transverse sealing in the packaging machine after the package has been filled with product.

The package 100 also includes a first bottom back panel 122, a left corner bottom panel 124, a bottom front panel 126, a right corner bottom panel 128, and a second bottom back panel 130 that together form the bottom of the package. In a similar manner to the first and second back panels 102, 110, the first and second bottom back panels 122, 130 are attached to each other. To close the package and thereby form the bottom, the first and second bottom back panels 122, 130 are each attached to the bottom front panel 126, two portions of the left corner bottom panel 124 are attached to each other, and two portions of the right corner bottom panel 128 are also attached to each other.

If the package 100 is produced in a roll-to-roll packaging machine, multiple sheets of packaging material are provided in sequence on a reel of packaging material. By arranging a plurality of sheets of packaging material in this way, a transverse seal forming the bottom can be made at the same time as a transverse seal forming the top of a subsequent package. After the transverse seals have been completed, the packages are separated from each other by cutting them through the section between the transverse seals.

To form the transverse seals, first and second top seal portions 134, 132 and first and second bottom seal portions 136, 138 may be provided. After the transverse seals are completed, the packaging material may be separated such that the first top seal portion 132 and the second top seal portion 134 form an upper portion of the top of the package 100 and the first bottom seal portion 136 and the second bottom seal portion 138 form a lower portion of the bottom of the package 100. A longitudinal seal may be formed using the longitudinal seal portion 140.

If the package is produced in a blank packaging machine, a longitudinal seal is provided in advance, i.e. the first back panel 102 is attached to the second back panel 110 by a longitudinal portion 140, thereby forming a sleeve-like sheet of packaging material. Furthermore, this separation (also referred to as cutting) is not carried out in the blank packaging machine, but rather when producing the blanks to be fed into the blank packaging machine.

Fig. 2 generally illustrates the principle of a reel-type packaging machine 200. A web 202 of packaging material is supplied via a reel and fed through the packaging machine 200 in a feed direction a. Tubes 204 are formed from the web 202. The food product can be fed into the tube 204 from above using a pipe 206 and a valve 208. In the folding and sealing apparatus 210, a package 212 is formed from the tube 204.

Fig. 3 generally illustrates, by way of example, a packaging material 300 that may be used to form the package 100.

Facing the surrounding space, an overcoat 302 may be provided. The outer coating 302 may be used to prevent moisture from contacting the print layer 304 disposed on the inside of the outer coating 302. The print layer 304 may comprise ink or any other material used to print on the package 100.

Inside the printed layer 304, a first cardboard layer 306 and a second cardboard layer 308 may be provided. The first and second paperboard layers 306, 308 provide stability to the package 100. The first paperboard layer 306 may be bleached paperboard with or without a clay coating. The second paperboard layer 308 may be bleached or unbleached paperboard.

Next, a laminate layer 310 made of plastic may be provided. The laminate layer 310 may enable prevention of contact of microorganisms with the product contained within the package 100.

Inside the lamination layer 310, an aluminium foil 312 may be provided. The aluminum foil 312 may allow light, oxygen, and odors to be prevented from coming into contact with the product within the package 100, and also allow the flavors within the package to be emitted from the package 100. But the aluminium foil 312 is not present in all types of packaging material. For example, in packaging materials for the packaging of refrigerated products (i.e., products to be frozen), the aluminum foil 312 is most often omitted and replaced by a combination of laminate and paperboard layers.

First and second interior coatings 314, 316 (which may be made of plastic, for example) may be provided proximate to the product contained within the package 100. One purpose of these internal coatings is to prevent the product from coming into direct contact with the aluminum foil 312.

Fig. 4 shows, by way of example, a cross-sectional view of the lower portion 400 of the package 100 generally in greater detail. The lower portion 400 may be formed from a first portion 402a and a second portion 402 b. Further, the package 100 may include outer layers 404a, 404b, stability layers 406a, 406b, which may be paperboard layers, and plastic layers 408a, 408 b. These various layers may in turn comprise a plurality of layers, as shown in fig. 3. During the sealing step in the packaging machine 200, the plastic layers 408a, 408b may be heated so that they melt, which may be done, for example, using induction heat sealing techniques or ultrasonic sealing. By combining it with holding the first and second portions 402a, 402b against each other, the plastic layers 408a, 408b may form fused layers 410a, 410b, which in turn enables the lower portion 400 to be formed.

During the sealing step, a sealing element provided with ridges may be used while keeping the first part 402a and the second part 402b held against each other. The ridge enables additional pressure to be provided in the ridge impression zone 412, which may be a sub-zone of the sealing portion 414.

Fig. 5 shows an example of a cross-sectional view of the seal portion 414 and the ridge imprint region 412 in the package 100 in more detail.

Fig. 6 shows by way of example a further cross-sectional view of the sealing portion. However, in this example of fig. 6, all layers other than the plastic layers 408a, 408b are omitted to clearly show how the plastic layers 408a, 408b are affected by the sealing step. That is, the plastic layers 408a, 408b are affected because the pressure applied during the sealing step thins the plastic layers 408a, 408 b.

Fig. 7 shows yet another example of the sealing portion 414, which is a front view thereof. One effect of the plastic layers 408a, 408b being affected during the sealing step is that light will face a different refractive index when transmitted through the lower portion 400 or any other portion comprising the sealing portion 414. Thus, by irradiating the lower portion 400 in a controlled manner, a quality assessment of the sealed portion 414 can be made.

Fig. 8a-c generally illustrate an apparatus 800 for quality assessment of the seal portion 414. The device makes use of the fact that: the light transmitted through the sealing portion 414 will be affected differently depending on how the packaging material 300 is affected during the sealing step.

As shown in fig. 8a, a sample 802 (which may be the lower portion 400 shown in fig. 4) may be placed in a sample holder 804 that contains a plurality of transparent plates 806. Light is provided by a lighting device 808 disposed on the first side I of the sample holder 804 through a light control device 810 having a light emitting area 812. Light is captured by a camera 814, which may be coupled to a camera mount 816, after passing through the plurality of transparent plates 806 and the sample 802, wherein the camera 814 may be placed on the second side II of the sample holder 804.

The image data acquired by the camera 814 may be transferred to a computer 818, which may be a laptop as shown, or may be an embedded processing device in the camera 814 or any other processing device configured to process the image data. The computer 818 may be equipped with a screen 820.

Fig. 8b shows the light control device 810 from a top view. The light emitting region 812 may have a first length L1 extending in a first length direction L1D and a first width W1 extending in a first width direction W1D. The first length direction L1D and the first width direction W1D may be perpendicular to each other. The first length L1 may be greater than the first width W1.

Fig. 8c shows the number of transparent plates 806 from a top view. The sample 802 including the sealing portion 414 may have a second length L2 extending in a second length direction L2D and a second width W2 extending in a second width direction W2D. The second length direction L2D and the second width direction W2D may be perpendicular to each other. The second length L2 may be greater than the second width W2. The sample 802 may be positioned such that the first length direction L1D is parallel to the second length direction L2D.

Fig. 9a and 9b show two examples of an apparatus 900 for quality assessment of the sealing portion 414. In fig. 9a the device 900 is shown without a polarizing filter and in fig. 9b the device 900 is shown with a polarizing filter.

More specifically, as shown in FIG. 9a, a sample holder 902 may be provided for holding a sample 904 having a spine impression region 906. Light 908 is emitted from the illumination device 910 and passes through the light control device 912 before reaching the sample holder 902 and the sample 904. The camera 914 may capture light passing through the sample holder 902 and the sample 906.

As shown in fig. 9b, the apparatus 900 further comprises a first polarizing filter 916 positioned between the sample holder 902 and the sample 904, and a second polarizing filter 918 positioned between the sample 904 and the camera 914. The first polarizing filter 916 may be a-45 degree polarizing filter and the second polarizing filter 918 may be a +45 degree polarizing filter. The effect of having polarizing filters 916, 918 may be that only light whose polarity is affected when passing through the sealed portion will be captured by the camera 914.

A light control device may be used such that image data may be captured with the light control device in a diffuse light position and the light control device in a high contrast position. Capturing image data at two different light settings has the advantage that different features can be determined more accurately. Different polarized lights (e.g., high contrast and diffuse lights) can be used to combine them. The linearly polarized light may have different angles with respect to the sample, e.g. 0 °, 30 °, 45 °, 90 °, etc., which has the advantage that different features may be determined in the image. Circular polarization may also be used, which also has the advantage of providing the possibility to detect different features in the image.

The device 1000 may be embodied in a number of different ways. Fig. 10 shows an example of an embodiment of an apparatus 1000. In this embodiment, no camera is provided for capturing light passing through the sealing portion, but only a sample holder 1002 is provided, which comprises inter alia an illumination device and a magnification device 1004. To evaluate the quality of the sealed portion, an operator, i.e., a user, may observe the sealed portion through the magnifying device 1004. In the case where a camera is provided, the magnification device 1004 may form part of the camera.

Fig. 11a and 11b show another embodiment of a device 1000. Consistent with the embodiment of the apparatus 1000 shown in fig. 10, a sample holder 1002 and a magnifying device 1004 may be provided. However, in addition to the embodiment shown in fig. 10, a camera stand 1100 may be provided. By using the camera stand 1100, a mobile phone 1102 with a camera or any other camera equipped device can be placed so that image data can be acquired using the camera of the mobile phone 1102.

In order to evaluate the quality of the sealing portion, different characteristics may be considered. Fig. 12 shows an example of the sealing portion 1200. In this example, the seal boundary line 1202 is determined using an image analysis algorithm. This can be achieved by using the following features: there is a difference between the pixel values of pixels that do not belong to the seal portion (i.e., are located above the seal boundary line 1202 in fig. 12) and the pixel values of pixels that belong to the seal portion (i.e., are located below the seal boundary line 1202 in fig. 12). Further, a reference line 1204 may be determined. In this example, the reference line 1204 is based on a ridge nip, i.e. a line formed by ridges placed on one or both sealing jaws used in the sealing step. Instead of using a ridge nip as the reference line 1204, a cut line (i.e. the end of the package) may be used as the reference line. When both the seal boundary line 1202 and the reference line 1204 have been determined, a seal cross-section evaluation region 1206 may be determined. Even though illustrated as covering only a portion of the width of the package, it should be understood that the sealing portion 1206 may cover the entire width of the package. Further, instead of determining the seal 1206 based on the upper seal boundary line shown as the seal boundary line 1202 and the reference line 1204, the seal portion evaluation region 1206 may be based on a lower seal boundary line (which is placed on the opposite side of the reference line 1204) and the reference line 1204. The seal evaluation area 1206 may still be selected to be determined on the upper and lower seal borderlines. If this option is used, the reference line 1204 may be used as a guide to reliably identify the upper and lower seal boundary lines.

Instead of or in combination with determining seal evaluation area 1206, one or more distance measures between reference line 1204 and seal boundary line 1202 may be determined.

As indicated above, different characteristics may be considered in evaluating the quality of the sealing portion. Seal section area 1206 may be one of these features. The different features may form a seal portion evaluation feature set. The seal assessment feature set may include only one feature, even though as a general rule, considering multiple features of different aspects will improve the reliability of the assessment.

Another feature that may form part of the seal section evaluation feature set is a boundary line deviation measure. Fig. 13 shows an example of a seal portion 1300, the metric being determined in the seal portion 1300. As shown in fig. 12, a seal portion boundary line 1302 and a reference line 1304 may be determined. To determine the boundary line deviation measure, an ideal seal portion boundary line 1306 may be used. The desired seal portion boundary line 1306 may be determined in different ways. One way to determine this is to use reference line 1304. Based on the reference line 1304 and theoretical models, it is possible to determine how the seal portion boundary line 1302 should ideally be. As shown in fig. 13, a sealing portion boundary line 1302 as an actual boundary line of a sealing portion and an ideal sealing portion boundary line 1306 as a theoretical boundary line (i.e., a set value) deviate from each other at some point. Generally, the greater the deviation between the two, the greater the likelihood of an insufficient seal.

Yet another feature that may form part of a seal section evaluation feature set is shown by way of example in fig. 14. In this example, the seal includes an upper seal boundary line 1402, a first reference line 1404, a second reference line 1406, and a lower seal boundary line 1408. The first and second reference lines 1404, 1406 can be first and second ridge nips.

As shown in fig. 14, the lower seal portion boundary line 1408 may include a peripheral non-seal portion 1410. The depth of these peripheral non-sealing portions 1410 can be determined and can be used as a feature of the sealing portion evaluation feature set. Generally, the deeper the peripheral non-sealing portion 1410, the greater the likelihood of an inadequate seal.

Fig. 15 shows yet another example of a seal portion 1500. Consistent with the example shown in fig. 14, the seal 1500 includes an upper seal boundary line 1502, a first reference line 1504, a second reference line 1506, and a lower seal boundary line 1508. However, it is different from the example shown in fig. 14. The example of fig. 15 includes an inner non-sealing portion 1510. Since the inner non-sealing portion 1510 may represent an inadequate seal, the area of the inner non-sealing portion 1510 may be determined and form part of the sealing portion evaluation feature set. Even though a plurality of inner non-sealing portions 1510 are shown by way of example, a single inner non-sealing portion may be used. Generally, the larger the area of the non-sealing portion 1510, the greater the likelihood of inadequate sealing.

Yet another feature that may form part of the seal section evaluation feature set is a reference line deviation measure. This characteristic may be determined by comparing the reference line (first reference line 1504 is used in the example shown in fig. 15) to an ideal reference line 1512. The ideal reference line 1512 may be determined in different ways. One option for determining the ideal reference line 1512 is: a straight line is fitted to many observations made in identifying the reference line 1504, for example by using regression analysis. One case where it is assumed that the reference line 1506 should be straight is that the reference line 1504 depicts a ridge nip and the ridges of the sealing jaw are straight. Generally, the greater the deviation between the two, the greater the likelihood of inadequate sealing.

Further, the seal portion evaluation feature set may include input sealing energy. By recording the amount of energy input during the sealing step, the set of reference features may be adapted such that, for example, in case the sealing portion evaluation region 1206 depends on the energy used during sealing, this energy may be compensated. The input sealing energy may also be used to determine whether an insufficient seal has been achieved in a straightforward manner. For example, if the input sealing energy is higher than a set threshold value, this may indicate that the sealing is not performed correctly, and thus there is an increased risk that the seal does not satisfy the set quality condition.

Instead of using the ridge nip as a reference line, a cutting line, i.e. the edge of the package, may be used as a reference line. Furthermore, the use of a ridge nip and a cutting line as reference lines may still be an option.

Fig. 16 is a flow chart illustrating steps of a method for quality assessment of the sealed portion 414. In a first step 1602, image data may be captured. In the image data, in a second step 1604, reference lines 1204, 1304, 1404, 1504 may be identified. Thereafter, the seal portion boundary lines 1202, 1302, 1402, 1502 may be identified in a third step 1606. Based on the reference lines 1204, 1304, 1404, 1504 and the seal section boundary lines 1202, 1302, 1402, 1502, a set of seal section evaluation features may be determined in a fourth step 1608. In a fifth step 1610, the seal portion evaluation feature set may be compared to a reference feature set. If the degree of matching is found to be within the tolerance range, the seal portion can be considered to satisfy the set condition, that is, sufficient sealing has been achieved.

Optionally, in a sixth step 1612, based on the reference line and the seal section boundary line, a seal section evaluation region 1206 can be determined and form a portion of a seal section evaluation feature set.

Alternatively, in a seventh step 1614, a boundary line deviation metric may be determined by comparing the seal portion boundary line 1302 to the ideal seal portion boundary line 1306 and form a portion of the seal portion evaluation feature set.

Optionally, in an eighth step 1616, a reference line deviation metric may be determined by comparing reference line 1504 with ideal reference line 1512 and form part of a seal portion evaluation feature set.

Optionally, in a ninth step 1618, a peripheral non-sealing portion 1410 may be identified, and in a tenth step 1620, the depth of the peripheral non-sealing portion 1410 may be determined and form part of a sealing portion evaluation feature set.

Optionally, in an eleventh step 1622, an inner non-sealing portion 1510 may be identified, and in a twelfth step 1624, a region of the inner non-sealing portion 1510 may be determined and formed as part of a sealing portion evaluation feature set.

Although the steps are shown in a particular order, they should be considered as one example of many possibilities.

From the above description, although a number of embodiments of the invention have been described and shown, the invention is not restricted thereto but can also be implemented in other ways within the scope of the subject-matter defined in the following claims.