Apparatus and method for inspecting a slot on a lid

Abstract

A device (1) for inspecting a slit (I) formed on a side surface (SL) of a plastic cap (T), comprising: a conveyor (11) for transporting the cap (T) along a path (P); an illuminator (10) configured to illuminate a side surface (SL) of the cover (T) placed at an inspection position, where the cover (T) at the inspection position is aligned with an inspection axis (I) oriented vertically and transversely to the path (P); a plurality of cameras (12) surrounding the inspection axis (I), the plurality of cameras being configured to capture image data representing a plurality of images of a side surface (SL) of the cover (T) at the inspection position; a control unit configured to receive the image data and to process the image data in order to derive therefrom information relating to the slit, said device being characterized in that the illuminator (10) comprises a side wall (101) extending around the inspection axis (I) in order to illuminate all side surfaces (SL) of the cover (T) with light rays converging towards the inspection axis (I), the side wall (101) defines an interior space and comprises an inlet opening (103) and an outlet opening (104) for allowing the lid (T) to enter and exit the interior space, respectively.

Description

Technical Field

[0001] The present invention relates to an apparatus and method for inspecting a slot in a cover. Background Art

[0002] The present invention is directed to the art of inspection of caps, and in particular inspection of slits (or recesses) on caps. Typically, a cap comprises a body and a tamper-evident ring, the body being connected to the tamper-evident ring by a connecting tear strip; more specifically, when a user twists the cap for the first time, the body separates from the tamper-evident ring, and the tamper-evident ring remains attached to the neck of a container. In other types of caps, such as those known as "tethered caps", a permanently attached area of ​​the tear strip does not tear and maintains the cap body attached to the tamper-evident ring; thus, tethered caps are prevented from being lost and help reduce clutter.

[0003] In conventional caps and tethered caps, the connecting strip may comprise a series of slits and bridges, that is to say tearable connection areas between the body and the tamper-evident ring; alternatively, and in particular in the case of tethered caps, the connecting strip may comprise recesses, that is to say narrow thickness portions that are thinner than the body and the tamper-evident ring and that tear when the cap is twisted for the first time. These slits or narrow thickness areas may be formed during the step of moulding the cap (by compression, injection or both) (e.g. inside the mould itself or by using a removable drawer in the mould) or during a step after moulding (e.g. by cutting the cap by using a specific knife or by a material removal process).

[0004] Therefore, in this field it is important that the slits or recesses are of high quality to facilitate opening by the user or to prevent unwanted tearing of the connection area.

[0005] Therefore, there is an increasing need to precisely inspect slits or recesses before applying lids to the respective containers.

[0006] Cutting forms a cut or a series of cuts. It should be noted that the present invention is applicable to the inspection of slits (or cuts) and / or recesses.

[0007] In the prior art, a solution is known, for example, in the patent document 102020000012214 in the name of the present applicant, in which a light source illuminates a portion of the side surface and a camera next to the cover captures image data of the illuminated portion; more specifically, the cover rotates around its own axis of symmetry so as to expose different portions of its side surface to the camera to allow the camera to capture an image of each portion. Incorporating such a solution into a cover production line reduces the production speed, since, in order to be inspected, each cover must be transported to the inspection device and rotated to capture an image of the entire surface of the cover. Other known solutions for inspecting plastic objects are described in the patent documents JP2017120201A, HP-H-09169392A, JP2001050898A and WO2017 / 196193A. JP2017120201A discloses a lamp arranged around the cover to be inspected; HP-H-09169392A discloses a laser beam illuminating the inside of the cover. However, there is still a need for a particularly precise and robust inspection device. Summary of the invention

[0008] An object of the present disclosure is to provide an apparatus and method for inspecting a slit on a cover that overcomes the above-mentioned disadvantages of the prior art.

[0009] In particular, the object of the present disclosure is to provide a device and method for inspecting slits on covers that can be easily implemented in a production line. Another object of the present disclosure is to propose a device and method for inspecting slits that allow obtaining an image of the side surface where the slit is clearly visible and produce an image with good contrast.

[0010] Another object of the present disclosure is to provide an apparatus and method for inspecting slits that ensure that the obtained images are realistic and natural.

[0011] These objects are fully achieved by the device and method of the present disclosure as characterized in the appended claims.

[0012] More specifically, the device comprises an illuminator configured as an illuminated cover. Preferably, the illuminator is configured as a side surface of the illuminated cover. More specifically, the side surface extends around the longitudinal axis, that is to say like a ring around the longitudinal axis. The cover further comprises a transverse surface, that is to say a surface connected to the side surface and oriented perpendicular to the longitudinal axis. The illuminator can be configured as a transverse surface of the illuminated cover.

[0013] The apparatus comprises a conveyor configured to transport the cover along a path. The path may be partially circular and / or partially linear. The path may include at least one substantially linear portion proximate to an illuminator. The illuminator is configured to illuminate a side surface of the cover when the cover is placed in an inspection position. At the inspection position, the cover is substantially aligned with an inspection axis, wherein the inspection axis is oriented vertically and transversely to the path. In other words, at the inspection position, the longitudinal axis of the cover is substantially aligned with the inspection axis. Since the cover is placed in the inspection position, it can be inspected.

[0014] The device includes a plurality of optical sensors or a plurality of cameras. The plurality of cameras surround an inspection axis. The plurality of cameras are configured to capture image data, wherein the image data represents a plurality of images of a side surface of the cover at an inspection position. In other words, each of the plurality of cameras is configured to capture image data, wherein the image data represents an image of a corresponding portion of the side surface of the cover. Thus, the plurality of cameras surround the inspection axis, and each camera frames a portion of the side surface, so that when the cover is aligned with the inspection axis, the plurality of cameras frames the entire side surface of the cover. Note that the inspection axis defines an inspection area, that is, an area in which the cover can be positioned for inspection. The inspection area preferably extends around the inspection axis so that the camera is still able to frame the side surface of the cover even when the cover is not fully aligned with the inspection axis.

[0015] The device comprises a control unit configured to receive and process the image data. More specifically, the control unit is configured to process the image data to derive information related to the slits on the cover.

[0016] In one embodiment, the illuminator comprises a side wall extending around the inspection axis. The side wall has a generally cylindrical shape extending around the inspection axis. In other embodiments, the side wall may have a parallelepiped shape or any other geometric shape extending around the inspection axis. More specifically, the side wall extends around the inspection axis to illuminate all side surfaces of the cover with light converging towards the inspection axis.

[0017] Preferably, the side wall defines an interior space. The side wall may include an inlet opening for allowing the cover to enter the interior space. The side wall may include an outlet opening for allowing the cover to exit the interior space. In particular, the interior space includes an inspection axis, i.e., an inspection area. Therefore, the conveyor is configured to transport the cover along a path, wherein the path includes a passage for the cover through the inlet of the side wall, a passage through the inspection axis (i.e., the inspection area), and a passage through the outlet of the side wall after the cover is inspected. In other words, the conveyor is configured to allow the cover to pass from the inlet of the side wall of the luminaire through the inspection axis to the outlet of the side wall of the luminaire.

[0018] Thus, the device allows to illuminate the entire side surface of the cover and to capture image data during the entry of the cover into the inspection area.

[0019] In an example embodiment, the apparatus comprises a collimator configured to collimate (i.e. direct) light emitted by the illuminator. Preferably, the collimator is configured to collimate the light towards the inspection axis. The collimator may be interposed between the illuminator (or more precisely, a side wall of the illuminator) and the inspection axis.

[0020] In one example, the collimator comprises a collimator grid. The collimator (i.e., the collimator grid) may extend (at least partially) around the inspection axis. The collimator (i.e., the collimator grid) may extend (at least partially) along a side wall of the illuminator. Alternatively, the collimator (i.e., the collimator grid) may be spaced apart from the side wall of the illuminator.

[0021] Preferably, the collimator (ie the collimation grid) describes a cylindrical shape around the examination axis, so that the light rays are directed radially perpendicular to the examination axis.

[0022] It should be noted that the illuminator is configured to illuminate the side surface of the cover with light emitted toward the inspection axis; therefore, the light emitted by the illuminator is diffused in all directions in the inner space, that is, the light is not guided.

[0023] The presence of the collimator allows to collimate the emitted light rays, which, due to the collimator, take a direction collimated towards the examination axis after being emitted by the illuminator. More specifically, in the case where the side walls of the illuminator have a cylindrical shape and the collimator (or collimator grid) extends along the side walls of the illuminator around the examination axis, the collimator (or collimator grid) is also cylindrical (i.e. it describes a cylindrical shape), so that the emitted light rays are radially collimated towards the examination axis. Collimated light rays have the advantage of enhancing the clarity and contrast of the image data. Indeed, due to the collimated light rays, the slits (or recesses) that appear in the image are sharply defined and effectively contrast with the rest of the cover.

[0024] Preferably, the collimating grid comprises a first collimating filter and a second collimating filter. In other words, the collimator comprises a first collimating filter and a second collimating filter to define a collimating grid, wherein the first collimating filter and the second collimating filter are oriented at a predetermined angle relative to each other; preferably, the first collimating filter and the second collimating filter are oriented at 90° relative to each other.

[0025] In one embodiment, the side wall of the luminaire includes a diffuser configured to diffuse light in the interior space of the luminaire. The luminaire includes a primary light source. The diffuser body (i.e., the side wall of the luminaire) may have an annular configuration. The primary light source may be arranged along an upper edge of the diffuser body (i.e., along an annular upper edge of the diffuser body) such that the diffuser body diffuses light from the primary light source in the interior space.

[0026] In one example, the diffuser body is made of a plastic material, preferably methacrylate.

[0027] Therefore, the function of the diffuser body is to diffuse the light from the main light source uniformly along the side wall of the luminaire all the way toward the inner space.For this purpose, the diffuser body extends along the side wall of the luminaire body.

[0028] In an example embodiment, the illuminator comprises a reflective layer configured to reflect light. Preferably, the reflective layer is applied on the outer surface of the diffuser body, facing the inner space to reflect light directed away from the inspection axis. The reflective layer may be made of a reflective material, that is, it may comprise a reflective film. Alternatively, the reflective layer may comprise micro-slits configured to reflect light, i.e. light rays. The purpose of the reflective layer is to increase the amount of light present in the inner space.

[0029] When there is a collimator, a diffuser body and a reflective layer, the diffuser body is interposed between the collimator and the reflective layer. For example, the reflective layer may extend along the side wall of the luminaire around the inspection axis. The luminaire may include an opaque layer, i.e., a layer configured to absorb or shield light from the environment outside the luminaire and directed toward the interior space of the luminaire and / or to absorb light from the interior space and directed toward the environment outside the luminaire. Preferably, the reflective layer is interposed between the opaque layer and the diffuser body so as to reflect light toward the interior space of the luminaire.

[0030] In one embodiment, the device includes a top wall coupled to the side walls of the illuminator to define a top of the interior space. In one example, the device includes an additional light source. Preferably, the additional light source is coupled to the top wall to emit light into the interior space from above. The collimator can be configured to collimate light emitted by the additional light source toward the inspection axis.

[0031] In one example, each of the plurality of images represents a corresponding portion of the side surface captured by a corresponding camera of the plurality of cameras. Preferably, the control unit is programmed to derive a developed image from each of the plurality of images, wherein the developed image shows the side surface of the cover represented in a plane. This allows an operator to better observe the entire side surface and the slit.

[0032] In one embodiment, the side wall includes a plurality of openings. Each camera defines a capture axis, and preferably, the capture axis of each camera is inclined relative to a plane perpendicular to the inspection axis. In one example, each camera is located at one of the plurality of openings. Thus, the capture axis passes through the opening, points to the inspection area and is inclined relative to a plane perpendicular to the inspection axis. In one embodiment, the capture axis is inclined at a variable angle, that is, the inclination of the capture axis relative to the plane perpendicular to the inspection axis is variable. The inclination may vary depending on the length of the side surface of the cover along the longitudinal axis.

[0033] In other words, the capture axis of the camera is tilted relative to a direction perpendicular to the inspection axis. This prevents the opening and / or the inlet opening and / or the outlet opening from being mirrored onto the side surface of the cover and thus captured, ie imaged, by the camera.

[0034] In an example embodiment, the apparatus comprises a shielding element. The shielding element is located inside the interior space. The shielding element may be located in a plane transverse to the inspection axis. The shielding element may be aligned with the inspection axis so that a cover placed at the inspection position is vertically interposed between the conveyor and the shielding element. Preferably, the shielding element is vertically movable relative to the conveyor to allow adjustment of the distance between the shielding element and the cover placed at the inspection position.

[0035] In one example, the device comprises a support cylinder. The support cylinder can be inserted into a receptacle in the top wall. Preferably, the support cylinder extends between a first end and a second end opposite the first end. The first end can be slidably connected to the top wall. Preferably, the support cylinder is aligned with the inspection axis. Preferably, the shielding element is connected to the second end. Therefore, the support cylinder is configured to slide relative to the top wall along the inspection axis so as to change the distance between the shielding element and the cover placed at the inspection position.

[0036] The shielding element is configured to (at least partially) shield light, that is to say (at least partially) absorb light. The shielding element allows shielding or limiting light that, due to reflections on components of the device, generates false reflections on the side surface of the cover that can be captured by the camera.

[0037] In one embodiment, the device includes an upper camera, which is located above the conveyor and defines a capture axis oriented along the inspection axis to observe the cover at the inspection position from above. The upper camera can be located in the top surface. For example, the top surface may include a support member for the camera, which is configured to support the upper camera. In another example, the shielding element or the supporting cylinder may include a housing for accommodating the upper camera or a supporting member supporting it. The shielding element (or the supporting cylinder) may include a compartment configured to accommodate the upper camera, and the shielding element may include an opening through which the capture axis of the upper camera passes to observe the cover from above. In another example, the device includes an external support member located outside the internal space of the illuminator. The external support member may be configured to support the upper camera and / or support multiple cameras. The top surface or the supporting cylinder or the shielding element may include an opening, and the upper camera may be located at the opening. The upper camera may be configured to capture image data representing an image of the lateral surface of the cover in the inspection area.

[0038] The control unit may be configured to process the image data to derive information relating to the lateral surface of the caps and / or to the placement of the caps on the conveyor.

[0039] In an exemplary embodiment, the upper camera is configured to capture a control image representing placement of the cap on the conveyor. The control unit can be connected to the upper camera to receive the control image. The control unit can be programmed to compare the control image with reference information representing a predetermined position of the cap aligned with the inspection axis. The control unit can be configured to process the image data based on the comparison to derive information related to the slit.

[0040] In one embodiment, the apparatus for inspecting slits on a cap may form part of a cap production system. The system may include a feed device configured to feed a series of caps to be inspected to a conveyor. The feed device may be configured to receive the series of caps as they leave a cap molding device.

[0041] The control unit may be configured to generate a correction signal based on a comparison between the control image and the reference information. The control unit may be configured to transmit the correction signal to the feeding device, and based on the correction signal the feeding device may be configured to correct the placement of the caps on the conveyor.

[0042] In one embodiment, the apparatus comprises a position sensor configured to capture a position signal indicative of placement of the cover at a predetermined position. The predetermined position may be located upstream of the inspection region (or upstream of the inspection axis). The predetermined position may be located along a path. The control unit may be configured to receive the position signal and instruct the camera to capture image data in a synchronized manner based on the position signal. The control unit may be configured to calculate a travel time taken for the cover to travel from the predetermined position to the inspection region, and instruct the camera to capture image data based on the travel time.

[0043] The present disclosure also provides a method for inspecting a slit formed on a side surface of a plastic cover.

[0044] The method includes the steps of transporting the plastic caps along a path on a conveyor, wherein the conveyor may be manufactured according to one or more aspects of the present disclosure.

[0045] The method comprises the step of illuminating the side surface of the cover with an illuminator, preferably when the cover is placed at an inspection position or close to an inspection axis. The inspection axis is oriented vertically and transversely to the path. More specifically, the illuminator can be manufactured according to one or more aspects of the present disclosure.

[0046] The method comprises capturing image data, preferably when the cover is in an inspection position, by a plurality of cameras, the image data representing a plurality of images of a side surface of the cover. The cameras in the plurality of cameras may be manufactured according to one or more aspects of the present disclosure. Preferably, the plurality of cameras surround an inspection axis.

[0047] The method includes the step of receiving image data performed by a control unit manufactured according to one or more aspects of the present disclosure. The control unit processes the image data to derive information related to the slit.

[0048] In one embodiment, the illuminator includes a side wall surrounding the inspection axis to simultaneously illuminate all side surfaces of the cap with light converging toward the inspection axis, the side wall defining the interior space and including an entrance opening and an exit opening for respectively allowing the cap to enter and exit the interior space. Thus, the method may include a step of simultaneously illuminating all side surfaces performed by the illuminator. In one example, the method includes a step of transporting the cap from the entrance of the interior space through the inspection axis to the exit of the interior space performed by a conveyor.

[0049] In an example embodiment, the method includes the step of collimating light emitted by the illuminator. The step of collimating can be performed by a collimator or by a collimation grid. The collimator or the collimation grid can be manufactured according to one or more aspects of the present disclosure. Preferably, the emitted light is collimated toward the inspection axis. The collimation grid can be interposed between the illuminator and the inspection axis to collimate the light emitted by the illuminator toward the inspection axis, and can extend around the inspection axis along the side wall of the illuminator to describe a cylindrical shape around the inspection axis so that the light is radially directed perpendicular to the inspection axis. Therefore, the method can include the step of directing the light along a radial direction perpendicular to the inspection axis.

[0050] In one embodiment, the side wall of the luminaire includes a diffuser body having an annular configuration, and the luminaire includes a main light source disposed along an upper edge of the diffuser body. The method may include a step of emitting light performed by the main light source. The method may include a step of diffusing light from the main light source in the interior space performed by the diffuser body.

[0051] In one example, the illuminator comprises a reflective layer, which preferably faces towards the interior space, and the method comprises a step of reflecting, performed by the reflective layer, the light rays directed away from the examination axis.

[0052] The side wall may comprise an opaque layer and the method may comprise the step of shielding light from an environment external to the luminaire directed towards an interior space of the luminaire and / or light from an interior space directed towards an environment external to the luminaire.

[0053] In one example, the method comprises the step of lighting from above performed by an additional luminaire, preferably coupled to a top wall, wherein the top wall is coupled to side walls of the luminaire to define a top of the interior space.

[0054] In one embodiment, each image of the plurality of images represents a respective portion of the side surface, and the method comprises the step of deriving a developed image from each image of the plurality of images performed by the control unit, wherein the developed image shows the side surface of the cover represented in a plane.

[0055] In one example, each camera defines a capture axis that is inclined relative to a plane perpendicular to the inspection axis, and the method includes a step performed by each camera to capture the side surface of the cover through an opening formed in a side wall of the illuminator. The method may include the step of varying the inclination of the capture axis.

[0056] For example, the method may include a step of shielding light performed by a shielding element manufactured according to one or more aspects of the present disclosure.

[0057] In one example, the method includes the step of viewing the caps in the inspection area from above by an upper camera located above the conveyor and defining a capture axis oriented along and aligned with the inspection axis.

[0058] The method may comprise the following steps, performed by the upper camera, of capturing a control image representing the placement of the cap on the conveyor when the cap is in the inspection position.

[0059] The method may include the steps of receiving a control image and comparing the control image with reference information representing a predetermined position of the cover aligned with the inspection axis, performed by the control unit. The method may include the steps of processing and generating information related to the slit based on the comparison, performed by the control unit.

[0060] In one embodiment, the method comprises a step performed by a feeding device of feeding a series of caps to be inspected to a conveyor.The method may comprise a step performed by a control unit of generating and transmitting a correction signal based on a comparison between the control image and the reference information.

[0061] The method may comprise a step of transmitting a correction signal to the feeding device, performed by the control unit, and a step of placing the caps on the conveyor, performed by the feeding device, based on the correction signal.

[0062] In one example, the method includes the step of capturing, by a position sensor, a position signal indicative of placement of the cover at a predetermined position. The method may include the step of receiving, by a control unit, the position signal and instructing a camera to capture image data in a synchronized manner based on the position signal. The method may include the step of calculating, by a control unit, a travel time taken for the cover to travel along a path from the predetermined position to the inspection area and instructing the camera to capture image data based on the travel time.

[0063] The present disclosure also relates to a production line for producing plastic covers. The production line includes a forming machine for manufacturing plastic covers in a continuous cycle. The forming machine includes a plurality of molds. The forming machine can be an intermittent type or a rotary type. The mold can be a compression mold or an injection mold, and the forming machine is configured to manufacture the cover by compression molding or injection molding, respectively. The production line may also include a cutting device, which is provided with a cutter (e.g., a knife or a laser generator) and is configured to receive the cover of the forming machine and to apply a slit to the cover by the cutter. The production line also includes a device for inspecting the slit formed on the side surface of the cover, the device having one or more features included in the present disclosure. If a cutting device is present, the inspection device is arranged downstream of the cutting device.

[0064] Likewise, the present disclosure also relates to a method for producing a plastic cover in a continuous cycle. The method includes the step of molding the cover by a forming machine (rotary or intermittent, by compression or injection molding). In addition, the method may include the step of processing the cover by a cutting device to apply a slit on the side surface of the plastic cover. The method also includes inspecting the slit formed on the side surface of the plastic cover by a method according to one or more features included in the present disclosure. If there is a processing step, the inspection is performed after the processing step. It is observed that in some example embodiments, there is no processing step because the slit may have been set on the side surface of the plastic cover when the cover is molded; in other words, in some example embodiments, the cover is molded with the slit; on the contrary, in other example embodiments, the cover is molded without a slit, and the slit is applied later (after the cover is formed) by a cutting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] This and other features of the present invention will become more apparent from the following description of preferred embodiments of the present invention, which are illustrated by way of example only in the accompanying drawings, in which:

[0066] - Figure 1 An apparatus according to one or more aspects of the present disclosure is shown;

[0067] - Figure 2 A cover according to one or more aspects of the present disclosure is shown;

[0068] - Figure 3A , Figure 3B shows a device according to one or more aspects of the present disclosure, Figure 3C shows a cross section of an apparatus according to one or more aspects of the present disclosure;

[0069] - Figure 4 A portion of a system including an apparatus according to one or more aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0070] Referring to the accompanying drawings, number 1 indicates a device for inspecting a slit formed on a cover T (e.g., a plastic cover) (preferably on a side surface SL of the cover T). The side surface SL of the cover T extends between a first end SL' and a second end SL" around a longitudinal axis L; the cover T also includes a transverse surface ST, which is connected to the side surface SL (e.g., connected to the first end SL' of the side surface SL) and is oriented perpendicular to the longitudinal axis L. The side surface SL of the cover T includes a joining area U, which includes a slit and / or one or more narrow thickness areas. The joining area U defines a main body C of the cover T and an anti-tamper seal BG. The slit is intermittent so that the main body C is connected to the anti-tamper seal BG through a connector (that is, an area of ​​the cover that does not include the slit (or narrow thickness area)).

[0071] The connection may be temporary, i.e., a connection configured to break when the user first unscrews the cap T from the container; in this case, the body C and the tamper-evident seal are permanently separated. Additionally or alternatively, the connection may be permanent (in this case, they may also be referred to as "tethers"), that is, a connection configured to allow the body C to move away from the tamper-evident seal: in this case, the body C and the tamper-evident seal BG remain attached to each other by a permanent connection.

[0072] The apparatus 1 comprises a conveyor 11 for conveying a cap T along a path P, the conveyor 11 comprising a substantially straight portion. In one embodiment, the conveyor 11 is a belt. The conveyor 11 is configured to hold the cap T in place (i.e., receive it in a supporting manner) while the cap T is conveyed along the path P. Preferably, the conveyor 11 is configured to hold the cap T on the conveyor 11 by suction. The cap T can be placed on the conveyor 11 with its transverse surface ST in contact with the conveyor 11, or with the second end SL" of the side surface SL in contact with the conveyor 11.

[0073] In one embodiment, the conveyor 11 comprises an infeed portion configured to receive an ordered series of caps T to be inspected from a supply device 2, wherein the supply device 2 is part of a system for producing caps T. In one embodiment, the conveyor 11 comprises an outfeed portion configured to deliver a series of inspected caps T to an outfeed device, wherein the outfeed device is part of a system for producing caps T.

[0074] The apparatus 1 comprises an illuminator 10 configured to illuminate a cap T, wherein the cap T is placed at an inspection position. At the inspection position, the longitudinal axis L of the cap T is substantially aligned with (or close to) the inspection axis I. The inspection axis I is perpendicular to the path P of the conveyor 11, specifically perpendicular to the straight portion of the path P. The illuminator 10 comprises a side wall 101 extending around the inspection axis I, the side wall 101 preferably having a cylindrical shape and defining an interior space. The illuminator 10 comprises a top wall 102, which is coupled to the side wall 101 to define the top of the interior space. The illuminator 10 comprises an inlet opening 103 and an outlet opening 104, the inlet opening 103 being formed in the side wall 101 to allow the cap T to enter the interior space, and the outlet opening 104 allowing the cap T to exit the interior space. More specifically, the conveyor 11 is configured to transport the cap T between the inlet opening 103 and the outlet opening 104 through the inspection axis I. It should be noted that the inspection axis I is located in the interior space of the illuminator 10. The inspection axis I defines an inspection area, that is to say an area of ​​the luminaire 10 close to the inspection axis I, in which area the cover T is placed for inspection.

[0075] The side wall 101 of the luminaire 10 includes a diffuser body 110 configured to diffuse light within the interior space of the luminaire 10. The luminaire 10 includes a main light source 111. The diffuser body 110 has an annular configuration and extends along the side wall 101 of the luminaire 10. The main light source 111 is positioned along an upper edge 110b of the diffuser body 110 so that the diffuser body 110 diffuses light from the main light source 111 in the interior space. The diffuser body 110 is preferably made of a methacrylate material.

[0076] The luminaire 10 includes a reflective layer 112 configured to reflect light, preferably a reflective film or a layer including micro slits. The reflective layer 112 is located on an outer surface 110e of the diffuser body 110, wherein the outer surface 110e of the diffuser body 110 is opposite to an inner surface 110i facing the inner space of the luminaire 10. The reflective surface 112 faces the inner space to reflect light directed toward the reflective layer 112. The reflective layer 112 extends along the side wall 101 of the luminaire 10.

[0077] The illuminator 10 comprises a collimator 113 configured to collimate the emitted light towards the inspection axis I. The collimator 113 comprises a first collimating filter and a second collimating filter oriented at 90° to each other to define a collimating grid. The collimator 113 is interposed between the inspection axis I and a diffuser body 110 of the illuminator 10 and extends around the inspection axis I. The collimator 113 is preferably located on an inner surface 110i of the diffuser body 110 so that the light diffused by the diffuser body 110 is collimated perpendicular to the inspection axis I.

[0078] The side wall 101 of the luminaire 10 comprises a plurality of openings 114 around an inspection axis I. The device 1 comprises a plurality of cameras 12 configured to capture image data, wherein the image data represent a plurality of images of a side surface SL of the cover T at an inspection position. Each camera 12 defines a capture axis R inclined relative to a plane perpendicular to the inspection axis I. Each camera 12 is located at one of the plurality of openings 114 of the side wall 101 so as to frame the side surface SL of the cover T.

[0079] The device 1 comprises a control unit configured to receive and process the image data to derive information related to the slits on the cover T. More specifically, each image of the plurality of images represents a respective portion of the side surface SL captured by a corresponding camera 12 of the plurality of cameras 12 .

[0080] Each image of the plurality of images represents a respective portion of the side surface SL, and the control unit is programmed to derive a developed image from each image of the plurality of images, wherein the developed image shows the side surface SL of the cover T represented in a plane.

[0081] The device 1 comprises a shielding element 13 located in the inner space, the shielding element 13 extending in a plane E transverse to the inspection axis I and aligned with the inspection axis I, so that the cover T at the inspection position is between the conveyor 11 and the shielding element 13. The device 1 comprises a support cylinder 14, which is inserted in the housing S of the top wall 102 and extends between a first end 14a and a second end 14b. The first end 14a of the support cylinder 14 is inserted in the housing S of the top wall so that the support cylinder 14 can slide, and the second end 14b is connected to the shielding element 13. The support cylinder 14 is aligned with the inspection axis I and slides along the inspection axis I to change the distance between the shielding element 13 and the cover T.

[0082] In an exemplary embodiment, the device 1 may include an upper camera 15 that defines a capture axis R' oriented along the inspection axis I. The support cylinder 14 may include an opening (e.g., formed in the shielding element 13), and the upper camera 15 may be located at the opening. The upper camera 15 may be supported by a support member 141 of the support cylinder 14. The upper camera 15 captures image data representing an image of the lateral surface ST of the cover T, and the control unit processes the image data to derive information related to the lateral surface ST of the cover T and / or the position of the cover T on the conveyor 11. The device 1 may include a locking element 16 that is configured to lock the support cylinder 14 in place along the inspection axis I. The locking element 15 may include a clamp 161 and a stop screw 162.

[0083] The device 1 includes a mounting assembly 17 configured to support the illuminator 10. The mounting assembly 17 includes a mounting flange 171 connected to the side wall 101 of the illuminator 10 externally (relative to the interior space of the illuminator 10). The mounting assembly 17 (specifically, the mounting flange 171) is configured to support a plurality of cameras 12 around the inspection axis I. The illuminator 10 is configured to slide along the inspection axis I relative to the mounting flange 171 so as to adjust its height relative to the plurality of cameras 12. The mounting flange 171 is also connected to a mounting wall 172 of the mounting assembly, surrounding the inspection axis I and located outside the illuminator 10. The mounting assembly 17 includes a locking element, which includes a mounting clamp 173 and a mounting screw 174 to fix the illuminator 10 in place along the inspection axis I relative to the mounting assembly 17.

[0084] In one embodiment, the apparatus 1 includes a box 18 configured to shield the luminaire 10 from light from outside the luminaire 10. The box 18 includes an inlet 181 and an outlet for the conveyor 11, which are located at an inlet opening 103 and an outlet opening 104, respectively, of a side wall 101 of the luminaire 10. The box 18 includes a pair of handles 182.

[0085] Operatively, in the step of inspecting the slits on the side surface SL of the cap T, the conveyor 11 conveys the cap T to be inspected along the path P. The conveyor 11 may receive an ordered series of caps T from the supply device 2. The conveyor 11 conveys the cap T to be inspected toward the inlet opening 103 formed in the side wall 101 of the illuminator 10. The side wall 101 defines an internal space in which the side surface SL of the cap T is illuminated. More specifically, the conveyor 11 conveys the cap toward an inspection axis I around which the side wall 101 of the illuminator 10 extends, so that the longitudinal axis L of the cap T is substantially aligned with the inspection axis I. When the cap is within the internal space, the primary light source 111 illuminates the side surface SL of the cap T. The light from the primary light source 111 is first diffused by the diffuser body 110 extending along the side wall 101 of the illuminator 10 and around the inspection axis I. Thus, the light is diffused within the internal space. The light is also reflected by a reflective layer 112, which extends along the side wall 101, around the inspection axis I and on the outer surface 110e of the diffuser body 110. The emitted light (i.e., both the light reflected by the reflective layer 112 and the light diffused by the diffuser body 110) is collimated by the collimating grid of the collimator 113. Thus, within the interior space, the light is directed radially toward the inspection axis I, toward the side surface SL of the cover T. A shielding element 13, which is positioned along the inspection axis I and extends transversely to the inspection axis I, shields some of the light. When the cover T is in the inspection position, a plurality of cameras 12 around the inspection axis I capture image data representing a plurality of images of the side surface SL.

[0086] In one embodiment, the position sensor captures a position signal indicating the placement of the cap T at a predetermined position upstream of the inspection axis I. The control unit receives the position signal and calculates the travel time taken for the cap T to travel from the predetermined position to the inspection area based on the speed of the conveyor 11, and instructs the camera 12 to capture image data based on the travel time. Each camera 12 captures image data representing a portion of the side surface of the cap and sends the data to the control unit. The control unit receives and processes the image data to derive information related to the slit on the cap. More specifically, the control unit derives a developed image from each of the multiple images, wherein the developed image shows the side surface SL of the cap T represented in a plane.

[0087] Next, the caps T thus inspected are transported toward the outlet opening 104 by the conveyor 11. Thereafter, the caps T may be delivered to a rejecting device.

Claims

1. An apparatus (1) for inspecting a slit formed on a side surface (SL) of a plastic cover (T), comprising: - a conveyor (11) configured to transport the caps (T) along a path (P); - an illuminator (10) configured to illuminate a side surface (SL) of said cover (T) placed in an inspection position, wherein said cover (T) in said inspection position is aligned with an inspection axis (I) oriented vertically and transversely to said path (P); - a plurality of cameras (12) surrounding the inspection axis (I) and configured to capture image data representing a plurality of images of the side surface (SL) of the cover (T) at the inspection position; - a control unit configured to receive and process said image data to derive information related to said slit, It is characterized in that the illuminator (10) comprises a side wall (101), which extends around the inspection axis (I) to illuminate all side surfaces (SL) of the cover (T) with light converging toward the inspection axis (I), and the side wall (101) defines an internal space and comprises an entrance opening (103) and an exit opening (104) for respectively allowing the cover to enter and exit the internal space.

2. The device (1) according to claim 1 comprises a collimator (113), which is between the illuminator (10) and the inspection axis (I) and is configured to collimate the light emitted by the illuminator (10) towards the inspection axis (I).

3. The device (1) according to claim 2, wherein the collimator (113) comprises a collimator grid, which extends along the side wall (101) of the illuminator (10) around the inspection axis (I) to describe a cylindrical shape around the inspection axis (I), so that the light is radially guided perpendicular to the inspection axis (I).

4. A device (1) according to any one of the preceding claims, wherein the side wall (101) of the luminaire (10) includes a diffuser body (110) having an annular structure, and wherein the luminaire (10) includes a main light source (111) arranged along an upper edge (110b) of the diffuser body (110), and the diffuser body (110) is configured to diffuse light from the main light source (111) in the internal space.

5. The device (1) according to claim 4, wherein the illuminator (10) comprises a reflective layer (112), which is applied on the outer surface (110e) of the diffuser body (110) and faces the inner space to reflect light directed away from the inspection axis (I).

6. The device (1) according to any one of the preceding claims, comprising a top wall (102) coupled to the side walls (101) of the luminaire (10) to define a top of the inner space.

7. The device (1) according to claim 6, comprising an additional light source (111) coupled to the top wall (102) to emit light into the inner space from above.

8. An apparatus (1) according to any one of the preceding claims, wherein each of the multiple images represents a corresponding portion of the side surface (SL) imaged by a corresponding camera (12) of the multiple cameras (12), and the control unit is programmed to derive a developed image from each of the multiple images, wherein the developed image shows the side surface (SL) of the cover (T) represented in a plane.

9. The device (1) according to any of the preceding claims, wherein the side wall (101) comprises a plurality of openings (114), each camera (12) being located at one opening (114) of the plurality of openings (114).

10. Device (1) according to any of the preceding claims, wherein each camera (12) defines a capture axis (R), and the capture axis (R) of each camera (12) is inclined relative to a plane perpendicular to the inspection axis (I).

11. The device (1) according to any one of the preceding claims, comprising a shielding element (13), wherein the shielding element (13): is located inside the inner space and extends in a plane (E) transverse to the inspection axis (I), aligned with the inspection axis (I), so that the cover (T) placed in the inspection position is vertically interposed between the conveyor (11) and the shielding element (13), It is vertically movable relative to the conveyor (11) to allow adjustment of the distance between the shielding element (13) and the cover (T) placed at the inspection position.

12. An apparatus (1) according to any one of the preceding claims, comprising an upper camera (15) located above the conveyor (11) and defining a capture axis (R') oriented along the inspection axis (I) to observe the cover (T) at the inspection position from above.

13. Apparatus (1) according to claim 12, wherein the upper camera (15) is configured to capture a control image representing the placement of the cap (T) on the conveyor (11), and wherein the control unit is connected to the upper camera (15) to receive the control image and is programmed to: - comparing said control image with reference information representing a predetermined position in which said cover (T) is aligned with said inspection axis (I); - processing the image data based on the comparison to derive information related to the slit.

14. An apparatus (1) according to any one of the preceding claims, comprising a position sensor, which is configured to capture a position signal indicating the placement of the cover (T) at a predetermined position upstream of the inspection area, wherein the control unit receives the position signal and instructs the camera (12) to capture image data in a synchronized manner based on the position signal.

15. A production line for manufacturing plastic caps (T), comprising: - a forming machine for manufacturing said plastic caps in a continuous cycle; - A device (1) for inspecting slits formed on the side surface (SL) of the plastic cover (T), said device being a device according to any one of the preceding claims.

16. A method for inspecting a slit formed on a side surface (SL) of a plastic cover (T), the method comprising the steps of: - transporting the plastic caps (T) along a path (P) by means of a conveyor (11); - illuminating the side surface (SL) of the cover (T) by means of an illuminator (10) when the cover (T) is placed in its inspection position aligned with an inspection axis (I), the inspection axis (I) being oriented vertically and transversely to the path (P); - when the cover (T) is in the inspection position, capturing image data by means of a plurality of cameras (12) around the inspection axis (I), the image data representing a plurality of images of the side surface (SL) of the cover (T); - receiving and processing said image data by a control unit to derive information related to said slit, The method is characterized in that the illuminator (10) comprises a side wall (101), which extends around the inspection axis (I) to simultaneously illuminate all side surfaces (SL) of the cover (T) with light converging toward the inspection axis (I), and the side wall (101) defines an internal space and comprises an entrance opening (103) and an exit opening (104) for respectively allowing the cover (T) to enter and exit the internal space.

17. The method according to claim 16 comprises the following steps performed by a collimator grid of a collimator (113): collimating the light emitted by the illuminator (10) toward the inspection axis (I), wherein the collimator grid is interposed between the illuminator (10) and the inspection axis (I) to collimate the light emitted by the illuminator (10) toward the inspection axis (I), and extends around the inspection axis (I) along the side wall (101) of the illuminator (10) to describe a cylindrical shape around the inspection axis (I), so that the light is directed radially perpendicular to the inspection axis (I).

18. The method according to claim 16 or 17, wherein the side wall (101) of the luminaire (10) comprises a diffuser body (110) having an annular configuration, and wherein the luminaire (10) comprises a primary light source (111) arranged along an upper edge (110b) of the diffuser body (110), the method comprising the following steps: - emitting light through a primary light source (111); - diffusing light from the primary light source (111) in the inner space through the diffuser body (110).

19. Method according to any one of claims 16 to 18, wherein each camera (12) defines a capture axis (R) which is inclined relative to a plane perpendicular to the inspection axis (I).

20. The method according to any one of claims 16 to 19, comprising the steps of: - when the cap (T) is placed in the inspection position, capturing a control image representing the placement of the cap (T) on the conveyor (11) by means of an upper camera (15), the upper camera (15) being located above the conveyor (11) and defining a capture axis (R') aligned with the inspection axis (I); - receiving, by means of the control unit, the control image and comparing it with reference information representative of a predetermined position in which the cover (T) is aligned with the inspection axis (I); - Processing and generating, by the control unit, information related to the slit based on the comparison.

21. A method for producing plastic caps (T) in a continuous cycle, comprising the following steps: - molding the cover by means of a molding machine; - Inspecting the slits formed on the side surface (SL) of the plastic cover (T) by the method according to any one of the preceding claims 16 to 20.

Images