Device for inspecting bottles

Abstract

A device for inspecting bottles, comprising a conveyor belt, a main structure through which the conveyor belt passes and on which an inspection area of ​​the bottle is defined, and three cameras arranged circumferentially around the inspection area. The cameras are each linked to a telecentric or plano-convex lens and oriented such that their optical axes converge substantially to the same point, forming an angle of substantially 120° to each other. The optical axes are substantially parallel to each other and parallel to a plane defined by the conveyor belt at the inspection area. The device also includes three light diffusers, each aligned with a specific optical axis and positioned diametrically opposite a respective camera with respect to the inspection area.

Description

Technical field

[0001] The present invention relates to a device for inspecting bottles and similar containers using cameras. State of the art

[0002] There are known bottle inspection systems that use a camera to capture one or more images, which can then be used to check for defects by special image recognition systems.

[0003] These inspection systems typically include one or more lighting devices that illuminate the bottle to highlight its features as much as possible and to detect cracks, chips, dirt and other similar defects in the captured images that would render the bottle unusable.

[0004] To visualize the bottle, and especially its neck, as effectively as possible, various solutions have been developed that combine multiple cameras to view the bottle from several angles. For example, French patent application FR3064068 (A1) describes a control system that uses two groups of three cameras arranged at two different positions along a conveyor belt.

[0005] The cameras are oriented differently towards each other in order to frame a respective section of the bottle and achieve a complete inspection of the bottle.

[0006] Another example is described in German patent application DE102012100987B3. In this case, there are four cameras arranged around the container to be inspected, and an equal number of lighting fixtures are arranged offset from the cameras.

[0007] However, the applicant pointed out that with known solutions it is particularly difficult to obtain a sufficiently clear and complete view of the bottleneck area.

[0008] Especially with bottles with screw caps, it is particularly difficult to obtain sufficiently detailed and complete images of both the thread profile and the thread surface unless the inspection is carried out in two separate steps.

[0009] The solution mentioned above proposes to divide the image acquisition into two different positions, each using a specific group of cameras to obtain a complete representation of the bottleneck.

[0010] Other solutions that use four cameras arranged around the bottle have the disadvantage that defects in the cap's thread profile cannot be adequately displayed, as only four different profiles can be imaged due to the cameras' two-fold mirroring. Furthermore, ensuring sufficient illumination remains difficult, as it is not possible to provide adequate backlighting for each camera. Summary of the invention

[0011] The technical problem underlying the present invention is to provide a device and a method for inspecting bottles that makes it possible to improve on known solutions and to at least partially eliminate one or more of the identifiable disadvantages in relation to the known technique.

[0012] Within the scope of this task, one object of the present invention is to provide a device for inspecting bottles that makes it possible to obtain a clear and complete image of the bottle neck with as few cameras as possible.

[0013] It is also an object of the present invention to provide an inspection device and a method that make it possible to improve the visibility, in particular with regard to the clarity and the details captured, of a section of the bottle and especially the neck and its closure with a structurally and technologically simple, rational solution and with modest effects on manufacturing costs as well as with a particularly small space requirement.

[0014] This problem is solved and one or more of these tasks are at least partially achieved by the invention through a device for inspecting bottles or other similar containers, comprising the following: • a conveyor belt; • a main structure through which the conveyor belt runs and where an area for bottle inspection is defined; • Three cameras arranged around the inspection area, each linked to a telecentric lens and / or a plano-convex lens.

[0015] The cameras are oriented so that the optical axes of the telecentric lens converge to the same point and form an angle of essentially 120° between the optical axes.

[0016] These optical axes are essentially parallel to each other and also parallel to a plane defined by the conveyor belt at the inspection area.

[0017] The device also includes three light diffusers, each aligned with a respective optical axis and positioned diametrically opposite a respective camera in relation to the inspection area, to form the respective reflectors.

[0018] It is estimated that the device according to the present invention enables effective backlighting of the bottle neck, although it is possible to achieve complete framing of the same essentially in a single area along the conveyor belt.

[0019] The use of telecentric lenses makes it possible to obtain a bundle for viewing with essentially parallel rays, making the image less susceptible to errors related to the positioning of the bottle on the conveyor belt.

[0020] In fact, the use of cameras with telecentric lenses makes it possible to obtain images of a uniform size even if the bottle is positioned inaccurately on the conveyor belt.

[0021] Furthermore, the use of telecentric lenses allows for a significant elimination of perspective aberration. In this way, the distortion phenomenon that typically occurs when using conical optics can be avoided.

[0022] Furthermore, by using telecentric lenses, a 180° arc can be framed on the bottle, which is in any case wider than with conical vision.

[0023] Similar advantages can be achieved, albeit to a lesser extent, with a plano-convex lens.

[0024] Furthermore, telecentric image acquisition units, i.e., image acquisition units already equipped with systems capable of obtaining a beam for viewing with substantially parallel rays, may also be suitable for use with the present invention, which includes inside a camera and a corresponding telecentric lens or equivalent systems.

[0025] Furthermore, the use of three cameras offset by 120° avoids the capture of mirror images, so that each camera obtains representative images of different areas of the thread. In this way, it is possible to obtain six different views of the thread, two for each camera, which leads to improved inspection accuracy.

[0026] Furthermore, the arrangement of the three cameras allows for a particularly small space requirement, especially from the perspective of the longitudinal development of the conveyor belt.

[0027] In another respect, the present invention also relates to a method for capturing images of a bottle or a similar container by a capture device comprising the features mentioned above.

[0028] Preferably, the method consists of capturing images from each of the three cameras in a successive time sequence, advantageously deactivating the associated light diffuser after capture by each camera.

[0029] Preferably, the cameras capture images with such a time delay that the bottle remains within the inspection area during continuous movement on the conveyor belt.

[0030] The present invention, as defined by one or more of the aforementioned aspects, may in addition to the aforementioned also have one or more of the following preferred features.

[0031] In some embodiments, these diffusers comprise a semi-transparent plate and at least one light source to produce diffused light for illuminating the bottle.

[0032] In some embodiments, these cameras are configured to cover the bottle with a width of essentially 180°. The images obtained from the three cameras can then be partially superimposed at the ends of each, so that the central part of the image is used to further improve the resolution. In other words, the telecentric lenses of the cameras each allow an image to be obtained that covers at least a 120° angle of the bottle, so that the three coordinated cameras can achieve a complete view of the entire circumference of the bottle.

[0033] In some embodiments, the device includes an additional camera positioned above the inspection area, defining a distinct optical axis that is substantially perpendicular to the inspection area. Preferably, the device includes a biconvex lens through which the additional camera frames the inspection area.

[0034] Thanks to this feature, it is possible to visualize further details of the bottle, in particular to observe the characteristics of any label that may be located on the bottle or the top of the opening. In some embodiments, the device additionally includes a lighting device arranged above this inspection area. Preferably, the lighting device is arranged around the perimeter of the inspection area above this area.

[0035] In some embodiments, the lighting device comprises a plurality of LEDs configured to illuminate the inspection area.

[0036] In some embodiments, the device includes adjustment means configured to set a vertical distance between the cameras and the plane defined by the conveyor belt. This feature allows for quick adjustment of the viewing device depending on the size of the bottles or containers to be inspected.

[0037] In some embodiments, the device includes a control panel. Preferably, the control panel is arranged laterally to the conveyor belt, with two of the cameras arranged on the same side of the control panel as the conveyor belt and the third camera arranged on the opposite side.

[0038] This arrangement is particularly advantageous because it allows the dimensions of the device to be optimized.

[0039] In some embodiments, the control panel includes a programmable unit configured to capture images from each of the three cameras in a successive time sequence, and is advantageously configured to deactivate the associated light diffuser after each camera has been captured.

[0040] In the present description, as well as in the claims attached thereto and more generally within the scope of the present invention, certain terms and expressions shall be deemed to have the meanings expressed in the following definitions, unless expressly stated otherwise.

[0041] In particular, the term “essentially the same”, which refers to the width of an angle, is understood to mean that the specified value may vary by ± 10%, preferably ± 5%.

[0042] The term “essentially parallel” means that two axes or two directions form an angle between ± 10°, preferably ± 5°, to each other.

[0043] The term "cone of view" refers to the shape described by the light rays that pass through an optical system to reach the sensor of a camera or, more generally, image capture devices.

[0044] The field of view does not necessarily have to be a regular geometric cone; it can be irregularly shaped or, in any case, deviate from the typical shape of a solid of revolution. The term "optical axis" refers to the axis that defines the camera's field of view. Brief description of the characters

[0045] The features and advantages of the invention are best revealed by the detailed description of some of its embodiments, which are presented as a guide and not as a limitation with reference to the accompanying drawings, in which: • Fig. 1 shows a schematic top view of the device of the present invention; • Fig. 2 a perspective top view of the device of the present invention; • Fig. 3 a perspective view of the device of the present invention from below, without the relative conveyor belt; • Fig. 4 is another perspective top view of the device of the present invention with corresponding protective cover; • Fig. 5A to 5C show different examples of images of bottle necks captured with the device according to the invention. Preferred embodiments of the invention

[0046] With reference to Fig. 1 is a device for inspecting a bottle B, with a total of 100 units.

[0047] The device 100 comprises a main structure 2, which is in Fig. 4 is more visible overall, with a corresponding outer housing 20 through which a conveyor belt 1 runs. A control panel 9 is also provided, via which the device can be operated and controlled.

[0048] In the main structure 2, an inspection area 20 of bottle B is further defined, which is carried along by the conveyor belt 1. During the pre-run, bottle B is advantageously positioned vertically on the belt 1, and the belt consequently defines a plane on which the bottle is placed.

[0049] Now, with renewed reference to Fig. 1 The device 100 comprises three cameras 3, which are arranged around the inspection area 20 and are arranged at an angle of 120°.

[0050] In preferred embodiments, each camera 3 comprises a telecentric lens 30, which enables the acquisition of a beam of substantially parallel rays for viewing F. In other words, the viewing cone of the camera 3 is oriented towards the telecentric lens, which is configured such that the bottle is observed through a beam F of parallel rays. These beams are wide enough to cover at least 120° of the bottle's circumference, so that the three coordinated cameras enable observation of the entire circumference.

[0051] As can be seen from the arrangement described above, the arrangement of the cameras 3 is such that the three optical axes V of the cameras form an angle of essentially 120° to each other.

[0052] Furthermore, the optical axes V are essentially parallel to each other and parallel to the plane that defines the conveyor belt 1 at the inspection area 20.

[0053] The cameras 3 are oriented such that the optical axes V of the three cameras 3 converge essentially to one and the same point on the inspection area 20. When inspecting bottle B, this point essentially coincides with the vertical axis of the bottle.

[0054] It should be noted that bottle B is advantageously in motion during the inspection by handling conveyor belt 1.

[0055] As a result, the optical axes V, as explained in more detail below, cannot perfectly coincide at one and the same point, so that the movement of the bottle is taken into account by each camera when capturing the image.

[0056] The device 100 further comprises three light diffusers 4, each aligned with a respective optical axis V and arranged diametrically opposite a respective camera with respect to the inspection area 20. In other words, the light diffusers 4 are advantageously also arranged offset from each other by 120° and are mirror images of the respective camera.

[0057] These light diffusers 4 provide backlighting for the section of the bottle framed by the respective camera. The combination of lighting provided by the three light diffusers allows for both direct illumination of the bottle and backlighting, ensuring sharp details of the visible part and its contours.

[0058] For this purpose, the diffusers 4 can comprise a semi-transparent plate and at least one light source to provide diffused light and avoid direct illumination of the bottle, thereby minimizing reflections on the glass or plastic of the bottle. It should be noted that the conveyor belt 1 defines two sides of the device 100, one facing the control panel 9 and the other opposite it.

[0059] As from Fig. As can be seen in Figure 1, two cameras and a light device are arranged on one of the two sides, and the other camera and the two light devices of the remaining two cameras are located on the other side. It should also be noted that, as shown in Figure 1, two cameras and a light device are arranged on one of the two sides, and the other camera and the two light devices of the remaining two cameras are located on the other side. Fig. 2 and Fig. 3 shows that the two cameras are arranged on the same side as the control panel 9.

[0060] With reference to the Fig. 2 and Fig.3. In some embodiments, the device 100 may include a further camera 5 arranged above the inspection area 20 for inspecting further details of the bottle. Preferably, the camera 5 has an optical axis V that is essentially vertical and directed towards the inspection area 20, i.e., above it.

[0061] Advantageously, an optical assembly consisting of a biconvex lens 6 is provided, through which the camera 5 frames the inspection area 20.

[0062] The biconvex lens makes it possible, in a manner known per se, to change the cone of view of the camera 5 so that one can observe the bottle around its entire circumference, in order to observe, for example, a label, if present, or other details.

[0063] The illumination of the camera 5 is preferably provided by a lighting device 7 arranged above the inspection area 20. The lighting device 5 is further preferably arranged in a lower position than the biconvex lens 6.

[0064] In some embodiments, the lighting device 7 may comprise a plurality of light sources 71 which, when the device is in use, are arranged around an opening 70 through which the modified cone of view of the camera passes through the biconvex lens 6.

[0065] The light sources 71 are advantageously designed by means of light-emitting diodes configured to illuminate the inspection area 20. Alternatively, the light sources 71 can also be designed by means of diffusers.

[0066] The light sources 71 are arranged around the optical axis of the camera 5 and are configured to produce a downward-directed beam of light and advantageously illuminate the inspection area 20.

[0067] The lighting device 7 is advantageously configured to define three different lighting areas arranged around the opening axis 70 at 120° intervals. These lighting areas, not shown in the figure, can advantageously be aligned with the cameras 3.

[0068] The control panel 9 is configured to link the switching on of each lighting area of ​​the lighting device 7 with the image capture by each of the three cameras.

[0069] This allows for further improvement of the illumination during image acquisition. It should be noted that the device 100 of the present invention can be configured to operate the three cameras sequentially, one after the other, together with the associated diffuser. The sequence can be so fast that stopping bottle B in its movement on conveyor belt 1 is not necessary.

[0070] This sequential process can be advantageously combined with switching on the lighting area corresponding to the respective camera, thereby increasing the illumination during image capture.

[0071] Once the recording by a camera is complete, the corresponding diffuser and, if applicable, the associated lighting area can be deactivated by switching on the following diffuser and the corresponding lighting area at the time of the next camera's recording.

[0072] It should be noted that the lighting device 7 can also be advantageously used in embodiments in which the upper camera 5 is not present.

[0073] In some embodiments, the device 100 further comprises adjusting means 8 configured to adjust the vertical distance between the cameras and the conveyor belt 1. For example, the adjusting means 8 may be formed from a series of screws over which camera holders 3 are moved.

[0074] The invention thus solves the proposed problem and simultaneously achieves a multitude of advantages, including the possibility of achieving optimal illumination of the container during its inspection, even though a relatively small number of cameras are used.

[0075] The invention is also used in bottles of general shape, provided the neck has a cylindrical shape or other axial symmetry. Furthermore, it can be used in bottles and containers made of any material, although it is particularly advantageous when used in bottles and similar containers made of reflective and preferably at least partially transparent materials such as glass and plastic. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] FR 3064068 (A1

[0004] DE 102012100987B3

[0006]

Claims

[1] Device (100) for inspecting bottles (B) comprising: • a conveyor belt (1); • a main structure (2) through which the conveyor belt (1) runs and at which an inspection area (20) of the bottle (B) is defined; • three cameras (3) arranged circumferentially around the inspection area (20) and each linked to a respective telecentric lens (30), wherein each of the cameras (3) together with the telecentric lenses (30) or a plano-convex lens, defines a respective optical axis (V), wherein the cameras (3) are oriented such that the optical axes (V) of the three cameras (3) converge to the same point and thus form an angle of substantially 120° to each other, wherein the optical axes are substantially parallel to each other and parallel to a plane defined by the conveyor belt (1) at the inspection area (20); • three light diffusers (4) each aligned with a respective optical axis (V) and arranged diametrically opposite a respective camera in relation to the inspection area (20). [2] Device (100) according to claim 1, comprising exactly three cameras (3) arranged around the inspection area (20). [3] Device (100) according to claim 1 or 2, comprising a further camera (5) arranged above the inspection area (20) and defining a respective optical axis (V') that is oriented substantially vertically to the inspection area (20). [4] Device (100) according to the preceding claim, comprising a biconvex lens (6) by which the further camera (5) frames the inspection area (20). [5] Device (100) according to claim 3 or 4, further comprising a lighting device (7) arranged above the inspection area (20), wherein the lighting device (7) is preferably configured to define three different lighting areas arranged offset by 120° around the inspection area, wherein the lighting areas are preferably aligned with the cameras (3). [6] Device (100) according to any of the preceding claims, comprising adjustment means (8) configured to set a vertical distance between the cameras and the plane defined by the conveyor belt (1). [7] Device (100) according to one of the preceding claims, comprising a control panel (9) arranged laterally to the conveyor belt (1), wherein two of the cameras (3) are arranged on the same side of the control panel to the conveyor belt (1) and the third camera (3) is arranged on the opposite side. [8] Device (100) according to any of the preceding claims, comprising a programmable unit configured to capture images from each of the three cameras (3) in a subsequent time sequence, wherein this programmable unit is configured to deactivate the light diffuser associated with it after capture by each camera. [9] Device (100) according to claims 5 and 8, wherein the programmable unit is configured to turn on each of these lighting areas sequentially, so that the lighting area associated with the camera capturing the image is turned on. [10] Method for inspecting bottles and similar containers using a device (100) designed according to one of the preceding claims, comprising capturing images from each of the three cameras (3) in a subsequent time sequence, wherein after capture by each camera the associated light diffuser is deactivated.

Images