Device and method for performing side wall inspection on pulp container

Abstract

The invention relates to a device and a method for inspecting the side wall of a pulp container. In particular to a device for optical inspection of pulp containers. The device comprises a lighting facility, and the opening part of the pulp container can be arranged below the lighting facility, so that light of the lighting facility can be irradiated into the lighting facility through the opening part of the pulp container; and a camera formed to record light passing through the side wall of the pulp container, thereby capturing an image of the side wall of the pulp container. In addition, the invention also provides a method for performing optical inspection on the pulp container.

Description

Technical Field

[0001] The invention relates to a device and a method for inspecting the side wall of a pulp container. Background Art

[0002] Before containers, such as beverage bottles and cans, can be used for filling, it must be ensured that they are free of any damage, such as cracks or holes, or dirt. Transparent containers can be inspected for dirt, foreign objects or damaged spots on the outside by shining light through them. For opaque cans, there is an inner wall inspection, where light is shone from a large area light source through a large can mouth that is approximately the same diameter as the can. Devices for optically inspecting containers are known, for example, from DE 11 2016 002 237 T5 and DE 10 2017 123 684 A1.

[0003] Pulp containers, on the other hand, are made of a diffuse, essentially opaque material, so direct inspection of the interior from the outside is not possible. However, in industrial applications, it is necessary to effectively inspect pulp containers for damage points and dirt before they are loaded into the filling system. Summary of the invention

[0004] The object of the invention is therefore to provide a device and a method by which a pulp container can be reliably and effectively checked for dirt or damaged spots. To this end, the invention provides a device according to claims 1 and 4, and a method according to claims 9 and 11.

[0005] According to the invention, the device for optically inspecting a pulp container comprises a lighting facility, wherein the mouth of the pulp container can be arranged below the lighting facility so that light of the lighting facility can be irradiated into the pulp container through the mouth of the pulp container, and a camera. The camera is formed to record light passing through the side wall of the pulp container, thereby taking an image of the side wall of the pulp container.

[0006] Thus, using the device, it is possible to illuminate the interior of a pulp container and observe the side wall of the pulp container with a camera. If the side wall has a damaged point in the form of a hole or a crack, light will pass through this damaged point and be detected by the camera. In the image captured by the camera, the damaged point can be identified as a bright spot and is clearly identified. The device is also suitable when the side wall of the pulp container has a location with a smaller wall thickness. Likewise, in the captured image, this location will appear brighter than the surrounding locations on the side wall. Locations with a smaller wall thickness in the side wall also fall under the general term for damaged points. Thus, in general, using the device, damaged points in the side wall of a pulp container can be effectively and reliably identified.

[0007] The pulp container can be composed entirely or mainly of a mixture of pulp called water, fiber and other additives as necessary. The fiber can be natural and biodegradable. The fiber can include lignin, banana leaves and / or quinine. The fiber can, for example, include cellulose fiber, conifer fiber, leafy shrub fiber and / or sycamore fiber and / or grass fiber, reed fiber and / or bamboo fiber or similar fiber. The fiber can include silk, spider silk, algae, natural fiber (such as Danube silk (DonauSilphie) fiber, hemp, corn, cotton), banana peel, orange peel, grass, straw, potato starch or treated cow dung. Cellulose fiber derived from artificial planting process can also be provided. In the case of wood, as the basic material of the fluid substance with fiber, in the case of material shortage, these alternative materials can replace the basic material in whole or in part. Similarly, the fiber can include a fiber mixture made of non-wood material, such as cotton, hemp and / or textile fiber.

[0008] The inner wall of a pulp container is understood to mean the entire surface which delimits the interior space, for example the interior of a pulp container. This includes, for example, the container bottom (hereinafter also referred to as bottom), the side walls and / or, if necessary, the container neck (for example for bottles). Alternatively, the side walls can also be referred to as jackets. Viewed from the outside, the pulp container is also delimited by the container bottom, the side walls and, if necessary, the container neck.

[0009] The camera may further be formed to detect a label applied to a side wall of the pulp container or a printing applied to a side wall of the pulp container.

[0010] In addition to the inspection of damaged spots described at the beginning, the device also allows a so-called print control to be performed. In this case, a test image of the label or print can be compared with a template to determine any deviations between the image and the template. Thus, the inspection of damaged spots and the inspection of correct labels or prints can be carried out in the same device, which increases the efficiency of the inspection and eliminates the need for a separate print control device.

[0011] The lighting arrangement may further comprise a light source, and an optical system having a reflector and / or a lens, such that the optical system is formed such that light emitted by the light source is emitted through the mouth of the pulp container.

[0012] By means of the optical system, the radiation path of the light of the light source can be adjusted precisely so that the largest possible proportion of the light is emitted into the interior of the pulp container through the mouth. This ensures good illumination of the interior of the pulp container while requiring low optical power from the light source. In particular, the optical system can be formed so that it looks like a lens with a large depth of field. In this way, the largest possible area can be uniformly exposed between the mouth and the bottom of the side wall of the pulp container, thereby enabling an efficient optical inspection.

[0013] The device may comprise a further lighting facility which is formed to diffusely illuminate the side wall of the pulp container from the outside. In particular, the further lighting facility may be arranged concentrically around the lighting facility above the mouth of the pulp container.

[0014] The further lighting device provides good lighting conditions for print control (contrast, exposure), thereby ensuring reliable print control. In particular, by concentrically surrounding the lighting device and the further lighting device arranged above the mouth, a particularly uniform illumination of the exterior of the pulp container can be achieved. This makes the identification of the label or the print even more reliable.

[0015] The present invention also provides an apparatus for optically inspecting a pulp container, comprising a lighting facility and a camera arranged above the pulp container and aimed at its mouth. The pulp container can be arranged relative to the lighting facility so that light from the lighting facility enters the interior of the pulp container through the side wall and / or the bottom of the pulp container, and the camera is formed to record light emitted from the interior of the pulp container, thereby capturing an image of the interior of the pulp container.

[0016] Pulp is partially transparent, so light partially penetrates the wall and diffuses in all directions in the interior of the pulp container. When the pulp absorption is low, the light in the interior of the pulp container strikes the inner wall several times, each time with a diffuse distribution of light. The interior is thus evenly illuminated. This creates good exposure conditions for taking images through the mouth of the pulp container, so that dirt, foreign objects and / or damaged spots on / in the bottom and side walls of the pulp container can be reliably identified.

[0017] The light provided by the lighting facility may be or include near infrared light, in particular in the wavelength range between 800 nm and 1500 nm.

[0018] The absorption of light by the container pulp and the printing on the outside of the sidewalls of the pulp container make the illumination of the interior of the pulp container poor, making dirt and foreign matter difficult to identify. Experiments have shown that light emitted in the above part of the electromagnetic spectrum is more transmissive through the pulp than visible light. In addition, many organic dyes used for printing also have high transmittance or are almost translucent in the near infrared region. If the appropriate wavelength and dye are selected for printing, the impact of printing on optical inspection can be reduced or even avoided.

[0019] However, the pulp container can also be illuminated with visible light, for example between 350 nm and 800 nm. The spectrum used can be the same for the lighting device and the further lighting device. Furthermore, the illumination by the lighting device and / or the further lighting device can be pulsed, i.e. pulsed light or light pulses are provided. For example, LEDs, in particular chip-on-board LEDs (COB-LEDs), are suitable for this. The duration of the light pulses can be between 2 µs and 1 ms.

[0020] The lighting fixture and the further lighting fixture can be controlled individually and independently with regard to the spectrum, power, switching times and / or pulse duration.

[0021] The lighting arrangement may be formed such that the side wall of the pulp container is diffusely illuminated.

[0022] In this context, the term "diffuse" means in particular that the side wall is completely illuminated, preferably with an almost constant spatial illumination intensity. This can be achieved, for example, by a lighting arrangement which completely surrounds the side wall of the pulp container. By diffuse illumination of the side wall, diffuse illumination of the interior of the pulp container is also achieved, which, as mentioned above, leads to a more reliable identification of foreign objects, dirt and / or damaged spots.

[0023] The device may further comprise a support, whereby the pulp container arranged thereon can be rotated about its longitudinal axis. The support may be used in both versions of the device, i.e. when the pulp container is exposed through its mouth, and when the side wall of the pulp container is illuminated from the outside.

[0024] The lighting device and the camera are mainly fixed in position and the pulp container is moved relative to the lighting device and the camera. By rotating about the longitudinal axis while the camera is looking at the same time, two advantages are basically achieved. On the one hand, in embodiments of the lighting device that does not surround the entire side wall of the pulp container, a diffuse illumination of the side wall and thus also of the interior can be achieved. When the interior of the pulp container is illuminated through its mouth, the entire side wall can still be checked for damaged points due to the rotation of the pulp container using the fixed position camera. On the other hand, a print control of the entire side wall is possible. Thus, any errors in printing or labeling can be reliably identified.

[0025] The device may further comprise a transport device, wherein the transport device is transparent or translucent so that the pulp container can be illuminated through the transport device.

[0026] For example, the light coupling is carried out through the side wall of the pulp container when the pulp container is located on a conveyor. The light coupling through the bottom can be achieved, for example, by a neck treatment, wherein the pulp container is transported suspended. The advantage of a transparent or translucent transport device is that the lighting facility and the camera can be integrated into the existing transport device, and no separate optical inspection device is required. As a result, the entire system can be simpler and more space-saving.

[0027] The device may also include a linear conveyor, such as a conveyor belt, for conveying the pulp container, wherein the conveyor is in particular an input. Furthermore, the device may include an arrangement of multiple cameras to achieve an all-round view of the pulp container. For example, the arrangement includes four cameras, wherein two cameras are each arranged next to the conveyor. The two cameras on each side may form an angle of 60 to 90 degrees, in particular 70 to 90 degrees, relative to the container.

[0028] Alternatively, a mirror cabinet can be used to provide an all-round view of the pulp container.

[0029] The present invention also provides a method for optically inspecting a pulp container, which comprises illuminating a portion of the inner wall of the pulp container through its mouth with a lighting device, and taking an image with a camera by recording light that passes through the side wall of the pulp container and is directed toward the camera.

[0030] The advantages described in connection with the device apply in the same way to the method described below.

[0031] Part of the method may be detecting a label attached to the side wall of the pulp container by a camera.

[0032] Furthermore, in addition to illuminating the side wall of the pulp container through its mouth, the side wall can also be illuminated from the outside. This can be achieved in particular by, for example, a further lighting device arranged concentrically around the lighting device and above the mouth.

[0033] The method can be extended by taking another image, for example a second image. In this process, the first image is taken by recording light that passes through the side wall of the pulp container and is directed to the camera. The second image is taken by directing light from another lighting device that is reflected or scattered from the outside of the side wall to the camera. Furthermore, the other lighting device, for example, diffusely illuminates the outside of the side wall.

[0034] The two images can be recorded in particular during the transport of the pulp container. For this purpose, the second image is recorded approximately 100 µs or less, in particular approximately 50 µs or less, after the first image. For this purpose, the lighting facility and the further lighting facility must also be configured to provide light pulses of defined duration at the two light recording time points.

[0035] In the method, the pulp container can be rotated about its longitudinal axis, wherein at the same time a label applied to a side wall of the pulp container is detected.

[0036] This method allows a comprehensive inspection of pulp containers. On the one hand, as described, the side wall of the pulp container can be reliably and completely inspected for damaged points. On the other hand, a print control of the entire side wall and optionally a profile measurement of the container are also possible. The method thus effectively combines two important steps for the quality control of pulp containers.

[0037] Another method for optically inspecting a pulp container comprises illuminating portions of the side walls and / or bottom of the pulp container with a lighting device so that part of the light shines through the side walls and / or bottom to the interior of the pulp container, and taking an image from the interior of the pulp container with a camera by recording light emitted through the mouth of the pulp container to the camera.

[0038] As described above, the method allows to reliably identify foreign objects, dirt and / or damaged spots on / in the bottom and / or on / in the side walls of the pulp container.

[0039] The light of the lighting facility may be or include near infrared light, in particular in the wavelength range between 800 nm and 1500 nm.

[0040] As already described in connection with the device, light, eg electromagnetic radiation, emitted in this wavelength range is better transmitted by the pulp and any printing on the side walls of the pulp container.

[0041] The side walls of the pulp container can be diffusely illuminated.

[0042] It will be appreciated that the methods may be suitably performed using the apparatus described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further features and advantages are explained below by means of the exemplary drawings, in which:

[0044] Figure 1 shows a schematic diagram of a device for optically inspecting a pulp container according to a first embodiment;

[0045] Figure 2 shows a schematic diagram of an apparatus for optically inspecting a pulp container according to a second embodiment;

[0046] Figure 3 shows a schematic diagram of an apparatus for optically inspecting a pulp container according to a third embodiment; and

[0047] Figure 4 A schematic diagram of a device for optically inspecting a pulp container according to a fourth embodiment is shown.

[0048] In the following text and in the drawings, unless otherwise specified, the same reference numerals are used for the same or corresponding elements in different embodiments. DETAILED DESCRIPTION

[0049] Figure 1 A device 1 for optically inspecting a pulp container 20 according to a first embodiment of the invention is shown as a schematic side view. The device 1 comprises a lighting device 10 arranged above the pulp container 20. The pulp container 20 itself has a bottom, a side wall 23 and a mouth 21. A damage point 22 in the form of a hole or a crack is formed in the side wall 23. The pulp container 20 is still arranged on a support 40. The support 40 is formed so that the pulp container 20 can be rotated about its longitudinal axis. In particular, the rotation can be performed continuously and / or at an angle greater than or equal to 360 degrees.

[0050] The lighting installation 10 shown comprises, in addition to the light source 11, an optical system 12, which in this case consists of two convex lenses. However, it should be understood that the optical system 12 is neither limited to the number of lenses shown nor to their shape and can, for example, be a system consisting of concave lenses and convex lenses. The optical system 12 is used to illuminate the interior of the pulp container better than the light source 11 alone can achieve. To this end, light is guided from the light source 11 so that it irradiates the interior of the pulp container 20 through the mouth 21. The optical system 12 achieves a higher light irradiation through the mouth and therefore a higher light yield, for example, the light source 11 requires a lower light power.

[0051] The device 1 further comprises a camera 30 facing the side wall 23 of the pulp container 20. The camera 30 is formed to record the light passing through the side wall 23 and take an image accordingly. Since the pulp container 20 is arranged on a rotating support 40, the camera 30 can inspect the entire side wall 23.

[0052] In the example shown, the side wall has a damage point 22, which light enters through the side wall 23 and is detected by the camera 30. In the image captured by the camera 30, the damage point appears as a bright point relative to the surroundings. As a result, the damage point 22 is reliably identified and, accordingly, the pulp container 20 is identified as defective.

[0053] Figure 2 A device 1 for optically inspecting a pulp container 20 according to a second embodiment of the present invention is shown as a schematic side view. The device 1 first comprises an illumination device 10 formed to emit light. The illumination device 10 is arranged so that a pulp container 20 can be positioned next to it, so that the side wall 23 of the pulp container 20 is illuminated by light. Since the pulp part is light-transmissive, part of the light is transmitted to the inside of the pulp container 20, so that the inside of the pulp container 20 is illuminated. In the example shown, the illumination device 10 matches the pulp container 20 in terms of its height to ensure that the entire side wall 23 of the pulp container 20 is illuminated.

[0054] The lighting device 10 may include a plurality of light sources 11, such as LEDs arranged on the lighting device 10. In this case, the number of light sources 10b shown and their arrangement should not be understood as limiting. For example, the light sources 10b may also be so-called chip-on-board LEDs, which are closely arranged to achieve high brightness. High brightness is conducive to achieving good illumination of the interior of the pulp container 20 and improving the reliability of identifying damaged points or dirt.

[0055] Furthermore, the lighting facility may emit light in the near infrared range, for example with a wavelength between 800 nm and 1500 nm. As mentioned previously, near infrared light is beneficial because it passes through pulp and organic dyes better. In this case, the printing on the pulp container does not affect the optical inspection.

[0056] The device further comprises a camera 30 which records light entering from the interior of the pulp container 20 through the mouth 21 of the pulp container 20, thereby generating an image of the interior of the pulp container 20. In this way, damaged spots, foreign objects and / or dirt are identified on the bottom or side walls 23 of the pulp container 20 and are accordingly identified as defective.

[0057] The pulp container 20 is arranged on a support 40 which is formed so that the pulp container 20 can be rotated about its (here vertical) longitudinal axis (indicated by the arrow). This has the advantage that the side wall 23 can be diffusely illuminated without the lighting device 10 having to completely surround the side wall 23 of the pulp container. The diffuse illumination of the side wall 23 automatically also leads to diffuse illumination of the interior of the pulp container, which provides good conditions for the exposure of the image taken by the camera. This enables a high reliability of the recognition of foreign objects, dirt and / or damaged points by means of a high image quality.

[0058] Alternatively, the device 1 described in the second embodiment can also provide illumination through the bottom of the pulp container 22. For this purpose, the support 40 on which the pulp container 20 is arranged can be used as a transport device, and the support 40 is transparent, for example, by being made of organic glass, glass or other transparent materials. Accordingly, the light source 10 must be arranged below the support 40 and facing the bottom of the pulp container 20. Instead of the support 40, the device can also include a neck handling facility as a transport device, so that the bottom of the pulp container 20 can be directly illuminated.

[0059] Figure 3 A third embodiment of the described device 1 is shown. This embodiment differs from the first embodiment in that it comprises a second lighting facility 13. The second lighting facility 13 is arranged concentrically around the lighting facility 10. The second lighting facility 13 is formed to diffusely illuminate the side wall 23 of the pulp container 20. By means of this illumination, a label or a print applied on the side wall 23 can be checked using a camera 30.

[0060] It is understood that this embodiment can be combined with a support, for example, to rotate the container about its longitudinal axis. In this way, damage points and the correctness of the label or printing can be checked over the entire side wall (360° view).

[0061] Figure 4 A device 1 for optically inspecting a pulp container 20 according to another embodiment is shown in a top view, which differs from the third embodiment described above in the following aspects. The lighting device 10 and the further lighting device 13 are schematically shown next to the pulp container 20, but the configuration can be understood as the lighting devices 10, 13 being arranged as follows. Figure 3 It is shown located above the pulp container 20.

[0062] Firstly, the device 1 comprises a linear conveyor 50, for example, in particular formed as an input conveyor belt. Compared to a rack, the conveyor 50 has the further advantage that a large number of containers can be transported in series, whereas otherwise a plurality of individual racks with associated transport mechanisms must be provided. Furthermore, the device 1 comprises an arrangement of a plurality of cameras 30, in this example four cameras 30, wherein two cameras 30 are respectively arranged on either side of the conveyor 50. The arrangement is in particular symmetrical with respect to the conveyor. However, it is understood that the number of cameras is not limited thereto.

[0063] The two cameras 30 on a given side of the conveyor 50 form an angle with respect to the pulp container 20, which in the example shown is approximately 60 degrees. However, the angle may be in the range between 60 and 90 degrees. By such an arrangement of the cameras 30, for example, an all-round view of the side wall 23 of the pulp container 20 can be achieved without placing the container 20 on a rotatable support. The resulting structural simplification allows a large number of containers to be inspected at a certain time.

[0064] In particular, damage point inspection and print control can be performed for the entire side wall 23 (360 degree view) in interaction with the two lighting facilities described. For this purpose, the two lighting facilities 10, 13 are pulsed light sources that only provide light for a certain period of time. For the first image, the lighting facility 10 is switched on and the camera 30 checks whether light passes through the side wall 23 of the pulp container 20. This is how damage points are identified. For the second image, the lighting facility 13 is switched on so that the side wall 23 is diffusely illuminated from the outside. This is used for print control. The method can be implemented using a camera 30 or an arrangement of multiple cameras 30.

[0065] At typical transport speeds of about 2 m / s on conveyors, this means that the spatial offset of the container between the two shots is only 0.1 mm. This offset is small enough so that the two images can be compared. Thus, a moving container can be checked for damage points and print control simultaneously with just one camera.

Claims

1. A device (1) for optically inspecting a pulp container (20), the device comprising: A lighting facility (10), wherein a mouth (21) of the pulp container (20) can be arranged below the lighting facility (10), so that light from the lighting facility (10) can be irradiated into the mouth (21) of the pulp container (20); and A camera (30) is formed to record light passing through a side wall (23) of the pulp container (20) so as to take an image of the side wall (23) of the pulp container (20).

2. The device (1) according to claim 1, wherein: The camera (30) is further formed to detect a label applied to the side wall (23) of the pulp container (20) or a printing applied to the side wall (23) of the pulp container (20).

3. The device (1) according to any one of the preceding claims, wherein: The lighting facility (10) comprises: a light source (11); and an optical system (12) having a reflector and / or a lens, The optical system (12) is formed so that the light emitted by the light source (11) is emitted through the mouth (31) of the pulp container (20).

4. The device (1) according to any one of the preceding claims, further comprising a further lighting device (13) for diffusely illuminating the side wall (23) of the pulp container (20) from the outside, in, The further lighting device (13) is arranged, in particular, concentrically around the lighting device (10) above the mouth (21) of the pulp container (20).

5. A device (1) for optically inspecting a pulp container (20), the device comprising: Lighting facilities (10); as well as a camera (30) disposed above the pulp container (20) and directed toward the mouth (21) thereof, The pulp container (20) can be arranged relative to the lighting facility (10) so that light from the lighting facility (10) enters the interior of the pulp container (20) through a side wall (23) and / or a bottom of the pulp container (20), and The camera (30) is configured to record light emitted from the interior of the pulp container (20), thereby capturing an image of the interior of the pulp container (20).

6. The device (1) according to claim 5, wherein: The lighting facility (10) is formed such that the side wall (23) of the pulp container (20) is diffusely illuminated.

7. The device (1) according to any one of the preceding claims, further comprising a support (40), whereby the pulp container (20) arranged thereon can be rotated about its longitudinal axis.

8. The device (1) according to any one of claims 1 to 6, further comprising a linear conveyor for transporting the pulp container (20) and one or more further cameras (30), in, The cameras (30) are disposed on both sides of the conveyor (50) and are arranged so that light from the pulp container (20) falls on the cameras (30).

9. A method for optically inspecting a pulp container (20), the method comprising: Using a lighting device (10) to illuminate a portion of the inner wall of the pulp container (20) through its opening (21); as well as An image is captured with a camera (30) by recording light that passes through the side wall (23) of the pulp container (20) towards the camera (30).

10. The method according to claim 9, wherein: A label attached to the side wall (23) of the pulp container is detected by the camera (30).

11. The method according to any one of claims 10 or 11, wherein: The pulp container (20) rotates about its longitudinal axis, and Therein, a label applied to the side wall (23) of the pulp container or a print applied to the side wall (23) of the pulp container (20) is detected.

12. The method according to any one of claims 9 to 11, further comprising: illuminating the side wall (23) of the pulp container (20) from the outside using another lighting device (13); as well as Another image is captured by the camera by directing light emitted from the other lighting facility reflected or scattered from the outside of the side wall toward the camera and recording it.

13. The method according to claim 12, wherein: The lighting facility (10) and the further lighting facility (13) respectively provide light pulses, and The image and the further image are captured at a time interval of 100 μs or less, in particular at a time interval of 50 μs or less.

14. A method for optically inspecting a pulp container (20), the method comprising: Using a lighting device (10) to illuminate a portion of the side wall (23) and / or the bottom of the pulp container (20), so that part of the light is irradiated to the interior of the pulp container (20) through the side wall (23) and / or the bottom; and An image is captured from the inside of the pulp container (20) by a camera (30) by recording light emitted toward the camera (30) through the mouth (21) of the pulp container (20).

15. The method according to any one of claims 9 to 14, wherein: The light of the lighting facility (10) is or includes near infrared light, in particular in the wavelength range between 800 nm and 1500 nm.

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