IT202200025362A1 - DEVICE FOR INTERNAL INSPECTION OF A CONTAINER - Google Patents

Description

Device for internal inspection of a container

DESCRIPTION

Technical scope

The present invention relates to a device for the internal inspection, by means of image acquisition, of containers provided with a hole for pouring a product. An example of this type of container, in which the invention finds application, is in particular represented by oil cans.

Technology background

In many technical sectors, such as the food and pharmaceutical sectors, there is a particular need to carry out visual checks on containers intended to be filled with a certain product.

An example of such a need is represented by oil cans, which due to their characteristics, determine a series of operational criticalities.

It should be noted that empty cans are normally produced by specialized companies that supply them to bottlers on pallets with several layers.

Between the production of cans and their use, a series of operational phases are foreseen: storage of cans at the manufacturer, transport to the bottler, storage at the bottler, sending pallets to production, depalletization, sending individual cans to the filler, filling and capping.

There is therefore the risk that, at the time of filling, the container may have foreign bodies inside it such as residues from processing, stains, rust, pieces of packaging, materials that have fallen inside or been introduced, insects, small animals, deformations, etc. that would make its use unacceptable. However, automatic filling lines do not allow for effective visual inspection of the cans, as it is clear that a can-by-can inspection by operators cannot be acceptable on an industrial level.

The difficulties in inspecting cans are essentially linked to the typical characteristics of these containers.

In fact, oil cans typically have a parallelepiped shape, often with a rounded rectangular section.

In correspondence with one of their upper faces there is also a hole of small diameter compared to the section of the can itself, which is used for filling the can and for emptying the product, possibly following the application of a mouldboard cap applied on the hole itself.

Often the hole is not on the axis of the container but near one of the short sides. Another critical issue is represented by the material they are normally made of, that is, shiny, reflective sheet metal, or with white enamel on the inside.

Attempts have been made to use automatic camera vision systems but with unsatisfactory results due to the difficulty of the camera in seeing, through a small hole, an area much larger than the hole itself.

Furthermore, lighting inside the container can also be particularly complex, as the presence of reflections can blind the camera or in any case prevent some of the internal areas of the container from being clearly inspected.

To better understand the above-mentioned issues, it is appropriate to recall some concepts relating to the functioning of cameras, and of vision systems in general.

These systems are in fact based on a sensor that collects the light rays that strike it and that come from the object that is "photographed". The light rays arrive at the sensor in a cone of vision that passes through the optics applied to the camera. The vertex of this cone is inside the optics and therefore distant from the part where the rays enter the optics themselves.

Figuratively speaking, it is as if the camera-optics group saw through a cone that has its vertex inside the optics.

Normally this is not a problem because the object being photographed is far enough away and there are no screens hiding it.

The case of cans is different, in which you can see the inside only by looking through the filling hole, which however is small compared to the section of the can. It would therefore be necessary to bring the optics as close as possible to the hole but at the same time leave enough space to create the illumination of the inside, without however this illumination, which operates on mirrored or highly reflective surfaces, creating a series of reflections that prevent the camera, by blinding it, from having a useful view of the inside or parts of it. These needs are in conflict with each other.

In practice, therefore, the use of vision systems in this sector has been abandoned.

The can is then turned upside down so that the filling hole is facing downwards. In addition, compressed air is sometimes blown into the can.

It is clear that these operations are not able to guarantee that any foreign bodies come out because, as mentioned, the hole is small compared to the section of the can, often on one side, with a raised edge towards the inside, and therefore they cannot come out from the hole. Furthermore, foreign bodies, in particular residues of decomposed animals and insects, may have attached themselves to the inside of the container.

Therefore, the problem underlying the present invention is to provide a device for the internal inspection of a container that is structurally and functionally designed to at least partially overcome one or more of the drawbacks complained of with reference to the cited prior art. It is also an object of the present invention to provide a device for the internal inspection of a container and a related inspection method that allows an adequate view of the internal surfaces of a container.

Another object of the present invention is to provide a device for the internal inspection of a container which is particularly suitable for the inspection of cans with a non-centrally positioned hole, such as those used for oil.

Another aim of the present invention is also to provide the art with a device for the internal inspection of a container and a related method that allows for the improvement of known solutions within the scope of a simple, rational solution with relatively low costs.

Description of the invention

This problem is solved and one or more of these objects are achieved, at least in part, by the invention by means of a device for the internal inspection of a container provided with an aperture hole comprising image acquisition means, which define a first cone of vision.

The device preferably comprising an optical assembly.

Preferably, the acquisition means are configured in such a way as to acquire an image of one or more internal surfaces of said container through said hole, said image framing said optical group.

Preferably the image acquisition means and said optical group are positioned in such a way as to acquire said image by framing said optical group.

Said optical group comprises at least one lens configured in such a way as to deviate the cone of vision of the acquisition means into a second cone of vision. Preferably, said second cone of vision has a respective vertex located substantially in correspondence with a mouth surface of the hole of the container.

Preferably the vertex of the second cone of vision is placed at a predetermined distance, downwards, from said optical group.

Advantageously, in this way the vertex of the viewing cone is placed substantially in correspondence with a mouth surface of the container hole.

It will be appreciated that the device according to the present invention allows to obtain images of the inside of containers through the relative emptying/filling hole, operating from the outside of the container. In this way the inspection can be carried out on a production line, by advancing the containers in line under the optical group and, therefore, the image acquisition means.

According to a second aspect, the invention also relates to a method for inspecting a container provided with an aperture hole comprising a step of providing image acquisition means, which define a viewing cone.

Preferably the method further comprises a step of providing an optical group. It is preferably envisaged to position a container underneath said optical group.

The method advantageously provides for a phase of diverting the cone of vision of the acquisition means into a second cone of vision which has a respective vertex located substantially in correspondence with a mouth surface of the hole of the container.

The same advantages described in relation to the first aspect can therefore also be achieved through this second aspect.

It will also be appreciated that the device and method according to the present invention are particularly advantageous where the container has one or more of these preferred features:

the container has at least one plane of symmetry, and the hole has its center located externally to said plane of symmetry;

the container has a parallelepiped shape;

the container includes internal walls with reflective surfaces;

the container is an oil can.

It is understood, however, that the invention may also find application in different types of containers.

The present invention may also have one or more of the following preferred features in addition to those previously mentioned.

In some embodiments, said hole is located in correspondence with an upper portion of said container and has said mouth surface with a substantially vertical axis.

Preferably the device comprises a lighting group configured to emit a light beam substantially in the direction of the vertex of said second cone of vision, said lighting group being preferably positioned in a lower position than said optical group.

Preferably, it is envisaged to illuminate an internal volume of said container by means of a light beam emitted from the outside of the container and directed towards the inside of said container by passing through said hole.

Thanks to these characteristics, it is possible to use a lighting system that, although placed externally to the container, is able to illuminate its internal volume effectively.

In some embodiments, said lighting group comprises a plurality of light sources, preferably arranged around an axis passing through said vertex of the second cone of vision and preferably configured in such a way as to create a light beam directed downwards and inclined with respect to a vertical axis.

Thanks to these features it is possible to obtain uniform illumination of the inside of the container.

In some embodiments said lighting group defines an aperture, said light sources being preferably arranged in a crown around said aperture. Preferably said second cone of vision being passed through said aperture.

Thanks to this feature, it is possible to illuminate the container without it hindering the acquisition of the image through the relevant acquisition means.

In preferred embodiments, said light sources are configured so as to emit light beams of different luminous intensity depending on their position around said aperture.

Preferably, said light sources are provided to emit light beams of different intensity depending on a distance between the respective light source and a wall of the container towards which the light beam generated by the respective light source is directed.

This feature is particularly advantageous in the case of containers in which the opening hole is placed in a non-symmetrical position. Advantageously, a lower intensity beam can be used if the wall is closer to the light source and, vice versa, a higher intensity beam if the wall is further away.

Preferably, said lighting group includes means for collimating said light sources. It may therefore be possible to collimate said light beam.

This way it is possible to limit reflections as much as possible.

In preferred embodiments, said collimating means comprise lenses or channels configured such that the light beam from each light source passes within the respective channel before being emitted downwards from said lighting assembly.

These solutions are both simple and economical to implement and are particularly well suited to the patented solution.

In preferred embodiments, an inspection area is defined at which the container to be inspected is placed.

Preferably, the optical group comprises at least two lenses, thus improving the image quality.

In preferred embodiments, means are present for adjusting the distance between the two lenses, allowing an image enlargement/reduction effect to be achieved, thus increasing/decreasing the inspectable areas.

In preferred embodiments, the means for adjusting the distance between the two lenses may comprise a support on which a first lens is mounted and a tube, sliding on the support, in which the second lens is mounted.

Preferably said image acquisition means define a viewing axis, said viewing axis being inclined with respect to a vertical direction.

Preferably, said method involves tilting a viewing axis of said image acquisition means.

Thanks to this feature, it is possible to obtain a better view of the inside of the container in the event that the opening hole is not in a symmetrical position, as commonly occurs in oil cans.

In some embodiments the inspection device comprises a support element for said image acquisition means and said optical group, said support element being movable along at least two perpendicular axes, preferably three perpendicular axes.

In this way the device according to the present invention can be easily adapted to the inspection of containers of different formats and types. In some embodiments the inspection device comprises a protection element, which preferably develops along a conical surface, through which passes said cone of vision and interposed between an emission area of said light beam and said lens, in such a way as to shield said cone of vision from further light sources.

This feature allows to limit any reflections from external lights. Further preferred aspects are also defined in the attached claims as well as in the following description.

Preferably, said vertex of said second viewing cone is located at the centre of said mouth surface of said hole, in such a way as to allow better observation of the internal volume of the container.

In this description as well as in the claims attached thereto, and more generally in the context of the present invention, some terms and expressions are deemed to assume, unless otherwise explicitly indicated, the meaning expressed in the definitions that follow.

In particular, the term "cone of vision" will be understood as the shape described by the light rays that pass through an optic to reach the sensor of a camera or in general of image acquisition devices.

The cone of vision will not necessarily have the shape of a regular geometric cone, but may have an irregular shape or in any case deviate from the typical shape of a solid of rotation.

The term "image acquisition means" refers to any vision system capable of acquiring at least one image in digital format. It can therefore include both video systems capable of acquiring images in sequence, i.e. films, and possibly photographic systems capable of acquiring a single image.

Brief description of the figures

The characteristics and advantages of the invention will be better understood from the detailed description of some of its embodiments illustrated, by way of example and not by way of limitation, with reference to the attached drawings in which:

Figure 1 is a side view, partially in section, of the device of the present invention; and

Figure 2 is an enlarged detail of the view in Figure 1.

Preferred ways of carrying out the invention

With reference to figure 1, the reference number 100 indicates a device for the internal inspection of a container 10 provided with an opening hole 10A.

In this embodiment, the container 10 is represented by an oil can. As can be seen from the figures, the container 10 therefore has the shape of a parallelepiped.

The position of the opening hole 10A is not central. More precisely, the center C of the hole 10A does not lie in the plane of symmetry a of the container 10, as can be observed from the detail in figure 2. The hole 10A is therefore closer to one of the sides of the container 10, typically one of the two shorter sides. In the other direction the hole 10A can either be placed symmetrically or, in this case, not centered.

It should also be noted that another characteristic typically present in oil cans is the presence of reflective internal surfaces 11.

Figure 1 illustrates different cans of different sizes, for example with capacities of 1 litre, 3 litres, 5 litres, which, as will be seen below, can all be inspected by the device 100 according to the present invention. The dimensions of the cans can therefore be different both in section and height. It is understood that the present invention can also find application in different types of containers.

The inspection device 100 of the present invention comprises image acquisition means 1 to which a relative first viewing cone 1A is associated, hereinafter also referred to as the first viewing cone.

Preferably the viewing axis V of the acquisition means is inclined with respect to a vertical direction.

The device 100 further comprises an optical group 2, positioned in such a way as to be framed by the image acquisition means 1.

During the inspection of the container 10 ? positioned in correspondence with an inspection area 4, configured in such a way that the hole 10A is positioned below said optical group 2.

In this way the acquisition means 1 frames the hole 10A indirectly, through the optical group 2. The image acquisition means 1 are therefore positioned in such a way as to acquire an image of one or more internal surfaces 11 of the container 10 through the hole 10A.

In fact, the optical group 2 comprises at least one lens 21 which is made in such a way as to deviate the cone of vision 1A of the acquisition means 1 into a second cone of vision 2A.

The lens 21 is therefore configured in such a way that the vertex of the second cone of vision 2A is located substantially in correspondence with a mouth surface of the hole of the container 10A, preferably in correspondence with one of its centres.

This position is defined at a predetermined distance d, downwards, from the said optical group 2 which is determined according to the container being inspected.

Although the example in figure 1 shows a single lens in the optical group, embodiments may include at least two lenses, allowing for better image quality.

Lenses can also be made in different ways, some of which are listed below for illustrative purposes:

a single converging lens, preferably of the aspherical type, for a simple and economical solution;

- two or more successive lenses, preferably of the aspherical type;

a single achromatic and aspherical converging lens;

two or more successive achromatic and aspherical lenses.

The realization with aspheric lenses is improved, in terms of image quality, if, as we will see later, a monochromatic illumination or a narrow band filter is used on the image acquisition media. In this case the image obtained is in grayscale.

The embodiment with at least two successive achromatic and aspheric lenses is particularly advantageous, which instead allows obtaining an excellent color image of the inside of the can by means of white light illumination. It will be appreciated that the presence of a color image allows optimal quality control of the possible presence of foreign bodies such as processing residues, stains, rust, pieces of packaging, materials fallen inside or introduced, insects, small animals, deformations, etc.

It should also be noted that, in the case where solutions with two or more lenses are used, special means may be provided to adjust the distance between the lenses.

The device 100 further comprises a lighting group 3 configured to emit a light beam substantially in the direction of the center of the hole. Note that the light beam is therefore also substantially directed towards the vertex of the second cone of vision 2A.

The lighting group 3 is preferably placed in a lower position than the said optical group 2.

Wherein said lighting group 3 comprises a plurality of light sources 31, which during use of the device are arranged around the hole 10A of the container.

In other words, the light sources 31 are arranged around an axis passing through said vertex of the second vision cone 2A and configured in such a way as to create a light beam directed downwards and inclined with respect to a vertical axis.

This can be achieved by creating, for example, a crown of small illuminators around the hole, such as LEDs or optical fibres, which point at an angle towards the hole itself but which have their light-emitting part not visible from inside the container.

For this purpose, the lighting group 3 can define an opening 30 around which the light sources 31 are arranged. As can be seen from the figure, the second cone of vision 2A passes through this opening 30.

In some embodiments, the light sources 31 are configured so as to emit light beams of different light intensity as a function of a distance between the respective light source 31 and an internal wall HA of the container towards which the light beam generated by the respective light source 31 is directed.

Consequently, the light sources 31 will be arranged in such a way as to have different intensities depending on their position around the aperture 30. The lighting group 3 also advantageously comprises collimating means 32 of the light sources 31.

In fact, given the shape of the edge of the filling hole and the fact that the external upper surface of the can is usually shiny and reflective, these illuminating rays should be well collimated, so as to enter the can directly and not illuminate and create reflections in the external area around the hole. The collimating means 32 may for example comprise lenses, not illustrated in the figure, and/or channels 33 configured in such a way that the light beam of each light source 31 passes inside the respective channel 33 before being emitted downwards by said lighting group.

In some embodiments, the device 100 further comprises a protection element 5, which preferably extends along a conical surface, through which the second cone of vision 2A passes. The protection element is advantageously interposed between an emission area 51 of the light beam produced by the lighting unit and the lens 21, in such a way as to shield said cone of vision from further light sources.

In order to inspect containers of different sizes, the device 100 may also comprise a support element for the image acquisition means 1 and the optical group 2, which allows for their translation. Translation may allow for the image acquisition means 1 and the optical group 2 to be adjustable both in height and transversally. For this purpose, the support element may be movable either along two perpendicular axes or along three perpendicular axes.

In addition to the ability to translate, the support element can also be tilted around one or more axes. The most complete movement and adjustment possibility is obtained by providing three tilt axes.

The invention thus solves the proposed problem, achieving at the same time a plurality of advantages, including:

- the image acquisition devices can be placed at a distance from the hole and look at the optical system and not the hole, with the advantage of being able to significantly increase the depth of the field of vision and have the inside of the containers in focus even if they are of different dimensions, compared to situations in which the acquisition devices are close to the hole and therefore close to the areas to be checked;

- the optical group can therefore be seen, without problems, by the image acquisition means through its cone of vision;

- the optical group can have a diameter independent from the diameter of the hole, even much larger;

- is there sufficient space to also create a suitable system that allows the interior of the container to be illuminated without creating harmful reflections;

- the lighting group can let the light rays enter inside the can without creating a zone of intense light around the hole.

Claims (16)

1. Inspection device (100) for the internal inspection of a container (10) provided with an opening hole (10A), said device (100) comprising image acquisition means (1), which define a first cone of vision (1A), and an optical group (2), wherein said image acquisition means (1) are configured in such a way as to acquire an image of one or more internal surfaces (11) of said container (10) framing said optical group (2) and being positioned in such a way as to acquire said image of one or more internal surfaces (11) of said container (10) framing said optical group (2) and being positioned in such a way as to acquire said image of one or more internal surfaces (11) of said container (10), framing said optical group (2) and being positioned in such a way as to acquire said image of one or more internal surfaces (11). internal surfaces (11) of said container (10) through said hole (10A), said optical group (2) comprising at least one lens (21) configured in such a way as to deviate the cone of vision (1A) of the acquisition means (1) into a second cone of vision (2A), said second cone of vision (2A) having a respective vertex located at a predetermined distance (d), downwards, from said optical group (2), in such a way that the vertex of the second cone of vision (2A) is located substantially in correspondence with a mouth surface of the hole of the container (10A). 2. An inspection device (100) according to the preceding claim, further comprising a lighting group (3) configured to emit a light beam substantially in the direction of the vertex of said second cone of vision (2A), such that said light beam is substantially in the direction of a centre of the mouth surface of the hole of the container (10A), said lighting group (3) being preferably positioned lower than said optical group (2). 3. Inspection device (100) according to the previous claim, wherein said lighting group (3) comprises a plurality of light sources (31), arranged around an axis passing through said vertex of the second vision cone (2A) and configured in such a way as to create a light beam directed downwards and inclined with respect to a vertical axis. 4. Inspection device (100) according to the preceding claim, wherein said lighting group (3) defines an aperture (30), said light sources (31) being arranged in a crown around said aperture (30), said second cone of vision (2A) passing through said aperture (30). 5. Inspection device (100) according to the preceding claim, wherein said light sources (31) are configured in such a way as to emit light beams of different light intensity depending on their position around said opening (30). 6. Inspection device (100) according to any of claims 3 to 6, wherein said lighting assembly (3) comprises collimating means (32) of said light sources (31). 7. Inspection device (100) according to any of the preceding claims, wherein said image acquisition means (1) define a viewing axis (V), said viewing axis (V) being inclined with respect to a vertical direction. 8. Inspection device (100) according to any of the preceding claims, comprising a protection element (5), which preferably develops along a conical surface, through which said cone of vision passes and interposed between an emission area (51) of said light beam and said lens (21), in such a way as to shield said cone of vision from further light sources. 9. Inspection device (100) according to any of the preceding claims, comprising a support element for said image acquisition means and said optical group, said support element being movable along at least two perpendicular axes, preferably three perpendicular axes. 10. Inspection device (100) according to any of the preceding claims, wherein said support element is tiltable about one or more axes. 11. Method for inspecting a container (10) provided with an opening (10A) comprising: - provide means of acquiring an image (1), which define a cone of vision (1A), - provide an optical group (2), - place a container (10) underneath said optical group (2), - divert the cone of vision (1A) of the acquisition means into a second cone of vision (2A) which has a respective vertex located substantially in correspondence with a mouth surface of the hole (10A) of the container (10). 12. A method for inspecting a container (10) according to the preceding claim, comprising illuminating an internal volume of said container (10) by means of a light beam emitted from the outside of the container (10) and directed towards the inside of said container (10) passing through said hole (10A). 13. A method for inspecting a container (10) according to claim 11 or 12, comprising collimating said light beam. 14. A method for inspecting a container (10) according to any of claims 11 to 13, wherein said hole (10A) is located in correspondence with an upper portion of said container (10) and has said mouth surface with a substantially vertical axis. 15. A method for inspecting a container (10) according to any of claims 11 to 14, comprising tilting a viewing axis (V) of said image acquisition means (1). 16. A method for inspecting a container (10) according to any of claims 11 to 15, wherein said light beam is generated by a plurality of light sources (31), said method comprising causing said light sources to emit light beams of different intensity as a function of a distance between the respective light source (31) and an internal wall (11A) of the container towards which the light beam generated by the respective light source (31) is directed.