Machine for inspecting containers

Abstract

Machine for testing containers, comprising: - a conveyor (2) configured to move a sequence of containers along a feed path; - at least one plate (3) mounted on the conveyor (2) and configured to receive a container (C) and rotate it about an axis thereof along the feed path to impart a controlled rotational movement to the container (C) independently of the movement of the plate (3) along the feed path; - a first motor unit connected to the conveyor (2) for rotating it, and a second motor unit connected to the at least one plate (3) for rotating it about itself, wherein the first motor unit and the second motor unit are independent of each other and can be controlled separately; - a first position sensor (4) configured to detect a position of the plate (3) relative to the feed path; - at least one second angular position sensor (5) configured to detect an angular position of the at least one plate (3) with respect to the axis of the container (C); - a fixed optical sensor (6) arranged on one side of the feed path and facing the latter and configured to capture a sequence of images of a side surface of the container (C) during the combined rotational and translational movement along the feed path, the optical sensor (6) being the only sensor for inspecting the containers arranged on this side of the feed path and the optical sensor (6) being a camera; - a control unit (7) connected to the optical sensor (6) and to the first and second position sensors (5) and configured to receive a position signal of the plate (3) with respect to the feed path from the first sensor (4); to receive an angular position signal of the plate (3) with respect to the axis of the container (C) from the second sensor (5); to capture the sequence of images as a function of the position of the plate (3) along the feed path and the angular position of the plate (3) itself; to select a different part of each image as a function of the position of the plate (3) with respect to the feed path detected by the first sensor (4) and as a function of the angular position of the plate (3) with respect to the axis of the container (C), detected by the second sensor (5); to analyse each of the image sections selected for carrying out the test individually or to reconstruct a representation of the side surface of the container (C) by joining the image sections of the image sequence without superimposing them, and to analyse this representation to carry out the test; wherein the control unit (7) is further configured to calculate and select the part of each image corresponding to the projection of the image section onto a plane tangential to the container (C) and perpendicular to the central viewing axis (S) of the optical sensor (6) to achieve the least perspective distortion.

Description

Technical area

[0001] The present invention relates to the technical field of machines for treating containers, preferably bottles, of various types, for example semi-transparent and opaque containers.

[0002] More specifically, the present invention relates to a machine for inspecting containers arranged to operate when the containers are transported along a conveyor line, and to an associated method for detecting the orientation of the containers.

[0003] More specifically, the present invention falls into the category of machines capable of scanning the entire lateral surface of containers in order to analyze identifying marks, stains, or the like that identify a particular configuration of the container itself.

[0004] Identifying the orientation of the containers is particularly useful for subsequent processing of the containers themselves, such as labeling, which must be done at some predefined locations on the bottle.

[0005] Alternatively, it should be noted that the present invention may be used for purposes other than identifying the orientation of the containers, for example, for purposes related to the analysis of the external characteristics of the container to assess the conformity of the product to the quality requirements specified by the customer. State of the art

[0006] Particularly in the field of bottle processing, it is known to load these onto conveyor belts, which can be implemented, for example, by rotating turntable conveyors or linear motors with movable carriages.

[0007] In any case, the conveyors comprise a plurality of rotating plates that are movable along a feed path and onto which the containers to be treated are loaded.

[0008] For example, with regard to rotating turntable conveyors, they comprise a plurality of rotating plates arranged along the circumference of the turntable onto which the bottles are loaded (one bottle per plate).

[0009] During normal operation of the conveyor system, the combined movement of the turntable and the individual plates causes the bottles to rotate (rotation around the plate's axis and rotation around the turntable's axis), gradually and sequentially exposing the entire side surface of the bottle to a suitable detector. In particular, according to the prior art, several detectors are mounted on the turntable, each on a plate.

[0010] As the bottle rotates around its axis, each detector scans the entire side surface of the bottle to detect the position of a distinguishing feature (commonly referred to as a 'point'), which, in the case of a glass bottle, may be the weld on the glass, an emblem applied to the glass (to which, for example, a label may be applied), or other features.

[0011] As soon as the sensor has detected the “spot” of the bottle, a connected control unit processes the signal and assigns it to the angle at which the plate is positioned at that moment.

[0012] In this way, it is possible to detect the orientation of the bottle on the plate and, for example, to attach a label to a desired location on the bottle.

[0013] The detectors are usually connected to the turntable in two preferred ways.

[0014] In a first possibility, a detector is provided for each plate, which is attached to the turntable via a corresponding bracket (internal or external) and is firmly connected to the turntable in order to track the respective bottle during the rotation of the turntable.

[0015] However, this well-known technique has some disadvantages.

[0016] A first disadvantage is that the presence of several sensors significantly complicates the structure of the turntable and increases its dimensions.

[0017] Another disadvantage is that a number of sensors must be installed that corresponds to the number of plates on the rotating turntable.

[0018] Finally, it should be noted that changing the format of the containers to be inspected during a work cycle is complex and time-consuming, as the sensors have to be replaced or adapted to the new container format.

[0019] Therefore, for large turntables or turntables with many stations, a high number of detection sensors is required, which increases the final cost of the turntable due to both the cost of the sensors themselves and the cost of the structures that support them and their installation.

[0020] To overcome these disadvantages, a second technology is known in which at least one detector (preferably in the form of a camera) is movable forwards and backwards along a predefined path and follows the rotating bottle, at least for this part of the path, in order to film the side surface.

[0021] This second known technology also has some disadvantages, mainly related to the fact that the detector moves outside the turntable, which requires additional space in that area, and the need to provide a special and sometimes complex movement system.

[0022] Other technologies involve the use of a single fixed camera aimed at the bottle feed path and configured to take a sequence of photographs that can be used to reconstruct the entire surface of the bottle.

[0023] Although this solution is simpler in structure, it has disadvantages that affect its performance.

[0024] The use of a single camera requires greater accuracy in image acquisition due to the angular shift caused by the rotation of the bottle compared to the fixed camera.

[0025] To ensure that the entire surface of the bottle is correctly reconstructed and the “point” is clearly identified, it is therefore known to activate the camera in such a way that images are taken that partially overlap in order to subsequently reconstruct the entire image of the side surface of the bottle.

[0026] However, this solution makes the processing of the collected information more complex, especially with regard to the reconstruction to be carried out.

[0027] In fact, it is necessary to first analyze the individual images taken in order to identify and compare the individual areas of overlap and only then to reconstruct the entire image.

[0028] It should be noted that the problems set out above using the example of a rotating turntable conveyor also occur in a linear motor conveyor with movable carriages, to which the present invention relates. Subject of the present invention

[0029] Against this background, the technical object of the present invention is to provide a machine for testing containers which eliminates at least some of the disadvantages of the prior art described above.

[0030] In particular, it is an object of the present invention to provide a machine for testing containers which is structurally simple and can perform a quick and accurate test at the same time.

[0031] The stated technical problem and the objectives are essentially achieved by a machine for testing containers having the technical features listed in one or more of the appended claims.

[0032] According to the present invention, a machine for inspecting containers is shown, comprising a conveyor configured to move a succession of containers along an infeed path on which is mounted at least one plate configured to receive a container and rotate it about an axis thereof along the infeed path to impart rotation and simultaneous infeed movement to the container.

[0033] The machine further comprises a first linear or angular position sensor configured to detect the position of the plate along the feed direction and at least one second angular position sensor configured to detect an angular position of the at least one plate with respect to the axis of the container.

[0034] The movements of the container in the feed direction and around itself are independent of each other because they are controlled by independent motors (e.g. there are no mechanical or electronic motion relationship chambers) and are controlled independently of each other.

[0035] The conveyor may be in two embodiments comprising a rotating turntable or a linear motor with carriage, as described in more detail below.

[0036] The machine further comprises at least one fixed optical sensor facing the feed path and configured to capture a sequence of images representing adjacent portions of a side surface of the container during its rotational movement, and a control unit configured to simultaneously activate the capture of the images depending on the angular position of the rotatable turntable and the angular position of the at least one plate.

[0037] There is only one optical sensor, at least as far as the side where it is installed in relation to the feed path is concerned.

[0038] It should be noted that the claimed solution provides for selecting a different portion of each image depending on the position of the plate with respect to the feed path, detected by the first sensor, and depending on the angular position of the plate with respect to the axis of the container, detected by the second sensor.

[0039] In other words, the selection of a first section of a first image depends on a first position of the plate along the feed path and its angular position relative to itself. A second section is obtained from a second image following the first and depends on a second position of the plate along the feed path and its angular position relative to itself. And so on...

[0040] Advantageously, such a solution avoids the need to superimpose images to reconstruct a representation of the lateral surface of the container C, since the use of special angular position sensors for the turntable and for the plate and the selection of different image sections corresponding to predefined angular positions make it possible to always precisely and accurately determine the effective position of the container and its orientation along the feed path and to clearly identify which angular position of the lateral surface was actually photographed.

[0041] The present invention also relates to a method for inspecting a container, which is carried out by arranging a container in a plate of a machine according to the present invention.

[0042] Subsequently, while the container is transported along the feed direction, the position of the plate along the feed and rotation directions of the plate around the axis of the container can be recorded individually and separately.

[0043] The method therefore provides for activating the optical sensor at predetermined combinations of angular positions of the turntable and the at least one plate to capture a sequence of images, each representing adjacent portions of the side surface of the container. In particular, the method provides for selecting a different portion of each image depending on the position of the plate relative to the feed path and depending on the angular position of the plate relative to the axis of the container.

[0044] The images of the sequence are then analyzed individually or side by side without overlay to reconstruct a representation of the side surface of the container.

[0045] Advantageously, the method proposed here is particularly efficient because the acquired images can be analyzed individually or simply side by side without the need for pre-analysis to identify the superimposed parts.

[0046] At the same time, the individual recording of the individual angular positions of both the turntable and the plate ensures that the entire side surface of the container is correctly inspected.

[0047] The dependent claims, which are incorporated herein by reference, correspond to various embodiments of the invention. Short description of the characters

[0048] Further features and advantages of the present invention will become more apparent from the general and therefore non-limiting description of a preferred but not exclusive embodiment of a machine for testing containers, as shown in the attached drawings, in which - Fig. Figure 1 schematically shows a machine according to the present invention; - Fig. 2 shows a detail of a possible embodiment of the machine; - the Fig. 3a, Fig. 3b and Fig. 3c schematically shows a graphical user interface on which the reconstruction of the side surface of the container can be displayed; - the Fig. 4 and Fig. 5 show possible operating configurations of the machine, with particular reference to the procedures for reconstructing the side surface; - Fig. Figure 6 shows an embodiment detail of the machine according to the present invention. Description of at least one preferred embodiment of the present invention

[0049] In the accompanying figures, reference numeral 1 generally designates a machine for controlling the container “C”, which in the following description will be referred to simply as machine 1.

[0050] The machine 1 comprises a conveyor 2 for transporting containers "C" along a feed path. The latter can have various shapes depending on the requirements, such as circular, oval, rectilinear, or anything else not expressly specified herein.

[0051] The machine 1 further comprises at least one plate 3 which is rotatable about an axis of rotation “Y” of the plate 3, which preferably coincides with the axis of rotation of the container “C”.

[0052] The present invention comprises at least two embodiments of the conveyor 2: a first embodiment in which the conveyor 2 comprises a rotating turntable, and a second embodiment (not shown in the attached figures) in which the conveyor is provided with a linear motor with a plurality of carriages movable along the feed path thanks to the electromagnetic field variation.

[0053] According to the first embodiment of the conveyor 2, the rotating turntable is rotatable about a rotation axis “X” of the turntable, which, when rotating, describes a feed path in the center of which the rotation axis “X” runs.

[0054] In particular, the at least one plate is arranged on a peripheral edge of the rotatable turntable 2 such that the rotational axis "Y" of the plate 3 (parallel to the rotational axis "X" of the turntable 2) intersects the feed path. In other words, during the rotation of the rotatable turntable 2, the rotational axis "Y" of the plate 3 moves along the feed path. In addition, each plate 3 defines a support surface for a container "C." Preferably, the machine 1 comprises a plurality of plates 3 arranged circumferentially around the rotatable turntable 2 at a predefined distance, referred to as the pitch of the turntable.

[0055] Each plate is configured to rotate about its own “Y” axis as it moves along the feed path.

[0056] In this way, the joint movement of the rotating turntable 2 and the plate 3 allows the containers “C” accommodated therein to be given a rotational movement (rotation about the rotation axis “Y” of the plate 3 and rotation about the rotation axis “X” of the rotating turntable 2).

[0057] In the embodiment with a linear motor, each plate 3 is mounted on a respective carriage which is movable along the feed path.

[0058] The machine 1 further comprises a first angular position sensor 4 configured to detect an angular position of the rotatable turntable 2 or the position of the plate 3 (or the carriage on which the plate 3 is mounted) along the feed path.

[0059] Such a first sensor 4 therefore makes it possible to know the exact orientation of the turntable 2 or the position of the plate 3 along the feed path at any time.

[0060] The machine 1 further comprises at least one second angular position sensor 5 configured to detect an angular position of the at least one plate 3 with respect to the rotation axis “Y”.

[0061] Preferably, the machine 1 comprises a second sensor 5 for each plate 3 in order to know at any time the exact orientation of the individual plates 3 directly and independently of the detections of the first sensor 4 on the turntable 2 or on the linear motor carriage.

[0062] In particular, in the case of the rotating turntable, the machine 1 comprises a first motor device connected to the rotating turntable 2 and a second motor device connected to the plate 3. Preferably, the first motor device is separate from the second motor device and can be controlled independently thereof, and vice versa.

[0063] If there are several plates 3, the second motor unit is connected to each individual plate so that each plate 3 can be rotated independently of the other plates 3 of the machine 1 and, of course, independently of the rotational movement of the turntable 2.

[0064] According to this aspect, the first sensor 4 comprises an encoder coupled to or integrated into the first motor unit, while the second sensor 5 comprises an encoder coupled to or integrated into the second motor unit.

[0065] In particular, the machine 1 may comprise a plurality of encoders coupled to the respective plates 3 in order to be able to detect the angular position of the individual plates independently of one another as they are rotated along the feed path under the action of the second motor device.

[0066] In the case of the linear motor, the first sensor 4 is implemented directly in the electromagnetic control and command system of the carriage along the feed path, while the second sensor 5 is formed in the control system for the rotation of the plate 3, which can be carried out by auxiliary carriages that mechanically act on the rotation of the plate 3 mounted on the main carriage as a function of the variation of the controlled mutual distance, and / or by electric motors mounted directly on board the carriage and / or by other methods not expressly mentioned here.The machine 1 further comprises a fixed optical sensor 6 facing the feed path and configured to capture a sequence of images each representing adjacent portions of a side surface of the container “C” during its rotation and feed movement along a predefined portion of the conveyor 2 (in the case of the turntable, this is a predefined angular portion).

[0067] In other words, the optical sensor 6 is located in a fixed position next to the feed path, so that it has a field of view that covers a predefined section of the feed path. As can be seen in the attached figures, there is only one optical sensor 6 for one side, preferably the outside, of the conveyor track 2 (only in the alternative embodiment of Fig. 2, there is an optical sensor 6 for each side: inside and outside). The optical sensor 6 can be realized, for example, by means of a camera capable of taking a sequence of photographs of different sections of the side surface of the rotating container "C".

[0068] The rotation and feed movement imparted to the container “C” is such that during the passage through the field of view of the optical sensor 6 the entire side surface of the container “C” is exposed and can be correctly detected.

[0069] In order to synchronize the acquisition of images during the rotation of the containers “C”, the machine comprises a control unit 7 configured to activate the optical sensor 6 to acquire the sequence of images as a function of the angular position of the rotating turntable 2 or plate 3 along the feed direction and of the angular position of at least one plate 3 with respect to the “Y” axis.

[0070] In other words, the control unit 7 receives from the first sensor 4 and the second sensor 5 the information about the angular position of the turntable 2 and the plate 3 through respective electrical signals representing the position along the feed path and the angular position of the plate 3, and uses this information to activate the capture of the images by the optical sensor 6.

[0071] In particular, the control unit 7 is configured to activate the optical sensor 6 in dependence on a plurality of predetermined combinations of angular positions of the rotatable turntable 2 and the at least one plate 3.

[0072] In other words, the selection of a first portion 9a of a first image depends on a first position of the plate 3 along the feed path and its angular position relative to itself. A second portion 9a is taken from a second image following the first and is related to a second position of the plate 3 along the feed path and its angular position relative to itself. And so on...

[0073] In this way, the acquisition of superimposed images becomes unnecessary, since the control unit knows exactly the orientation of the container "C" (which results from the combination of the angular position of the rotating turntable 2 or plate 3 along the feed direction and of plate 3 with respect to the "Y" axis on which this container "C" rests) and thus clearly identifies which part of its lateral surface is being inspected.

[0074] In particular, the control unit 7 is configured to individually analyze or reconstruct a representation of the entire lateral surface of the container “C” by arranging the images of the image sequence to be analyzed side by side without superimposing them.

[0075] As in the Fig. 3a-3c, the control unit can also be connected to or directly comprise a graphical interface 8, on which both the field of view of the optical sensor 6 and the progressive reconstruction of the side surface of the container "C" can be displayed. Such a reconstruction can be carried out, for example, according to the Fig. described procedures (according to the procedure described in the Fig. shown), whereby the overall image is reconstructed by sequentially aligning the partial images in a row.

[0076] In particular, a first image section 9a is used as a starting point and positioned at a fixed lateral reference "A" (for example, a right, left, or center end of a display 8a of the graphical interface 8) and as a reference for the reconstruction of the image. Subsequently, in further steps, a second image section 9b and a third image section 9c are appended to this first image section 1a. Therefore, the control unit 7 generally receives the images captured by the optical sensor 6 one after the other when the container "C" is in a sequence of predefined positions and arranges them sequentially next to each other, with the ends aligned without overlapping.

[0077] Alternatively, the control unit 7 receives successively the images captured by the optical sensor 6 when the container “C” is in a sequence of predefined positions and analyses them individually, without having to superimpose them, in order to carry out the complete reconstruction of the lateral surface of the container “C”.

[0078] According to the present invention, the control unit 7 is configured to select a different portion of each image corresponding to a specific position of the plate 3 along the feed path. The portions selected for each image define the reconstruction of the representation of the side surface of the container C or are analyzed individually.

[0079] In other words, the control unit 7 is configured for: - receiving the images captured by the optical sensor 6; - to select a part (or section) of each image corresponding to a specific position of the plate 3 along the feed path; - to join the selected parts together without overlapping them so that they form the complete image of the side surface of the container “C”, or to analyse the selected parts individually.

[0080] It should be noted that the part of each image corresponds to a part of the field of view of the sensor 6.

[0081] The detailed Fig. show a sequence of capture and selection of the images captured by sensor 6, with container "C" moving from right to left while simultaneously rotating. The dashed parallel lines in the top left of each figure represent the selected image section.

[0082] In practice, sensor 6 detects the container ‘C’ entering its field of view from the right and moving to the left, and takes a series of photographs, each of which selects a different section to contribute to the composition of the overall image or to be analyzed.

[0083] In any case, it should be noted that the control unit 7 assigns to each detected image section the information about the position of the container “C” along the direction of movement and the angular position of the container “C” around itself (information received from the position sensors 4 and 5) at that precise time.

[0084] In other words, there is an exact relationship between the selected image section and the position of the plate 3 along the movement path.

[0085] Assuming there is an optical sensor 6 with a width of 1400 pixels and image patches of 100 pixels each, and 14 images are to be captured, the control unit is configured to select the first image patch between 0 and 100 pixels of the first captured image, the second image patch between 101 and 200 pixels of the second captured image, and so on.

[0086] In particular, the central extension axis of the selected portion of each image moves along the field of view of the sensor 6 and the associated acquired images in dependence on the movement of the container “C” along the feed path.

[0087] In one embodiment, the control unit 7 receives the image sections directly (and does not select them) from the optical sensor 6, since different detection sectors of the same optical sensor 6 are activated to already detect a respective image sector to be analyzed individually or flanked without superimposition with subsequent image sectors to define the representation of the side surface of the container C.

[0088] In other words, this embodiment provides for capturing the image parts to be analyzed or required for composing the overall representation of the side surface of the container C.

[0089] The detection sectors of the optical sensor 6 are activated sequentially depending on the position of the container “C” along the feed direction with respect to the position of the optical sensor 6, according to the same principle that applies, mutatis mutandis, to the selection of the part of the image described above.

[0090] In any case, as already explained above, each image section (or capture sector) has a width equal to the division of the total width of the image captured by the optical sensor 6 by the number of images captured by the optical sensor 6 itself. Returning to the previous example, each image section has a width of 100 pixels (out of a total of 14 images to obtain 1400 pixels of the total image).

[0091] According to one aspect of the present invention, the control unit 7 is configured to select the part of each image that has the least perspective distortion with respect to the optical sensor 6.

[0092] As in Fig. 6, the part of each image with the least perspective distortion corresponds to the projection of the image part onto a plane that is tangential to the container “C” and perpendicular to a central viewing axis “S” of the optical sensor 6.

[0093] In other words, the control unit 7 is configured to calculate the part of each image with the least perspective distortion with respect to the plane tangent to the container “C” and perpendicular to the central axis “S” and consequently select that part of the image.

[0094] In this way, it is advantageously possible to select the view with the least deformation or distortion of a particular image section, taking into account the angular deviation of the container “C” with respect to the central axis “S”.

[0095] This system allows the entire image of the side surface of container "C" to be reconstructed without superimposing the various image parts (just juxtaposing them) and then analyzed for verification. Alternatively, it is also possible to analyze each image part individually for verification (without performing reconstruction).

[0096] In one embodiment that is part of the present invention, one or more of the image sections has a width greater than the division of the total width of the image captured by the optical sensor 6 by the number of images captured by the optical sensor 6 itself. In this way, one and the same feature ("spot" or weld seam of the bottle, or the like) of a container "C" is visible in different consecutive image sections.

[0097] In this case, the control unit 7 does not perform flanking and reconstruction of the entire image, but analyzes each individual image section.

[0098] Advantageously, such an embodiment allows the identification of less significant "spots" (such as the vertical weld of the bottle glass) that may not be visible in a single image patch due to light reflections on the container "C". By capturing patches of a larger width (relative to the precise subdivision of the number of photographs), it is therefore possible to locate the "spot" in one or more consecutive patches in order to select the patch in which the "spot" is more clearly visible compared to other patches, for example, due to a different (and more favorable) reflection of light on the container "C".

[0099] In the latter case, the control unit 7 is configured to analyze each individual image section and identify the "spot" within the selected image section. Furthermore, the control unit 7 can be configured to identify the position of the "spot" relative to the entire lateral surface of the container "C" by knowing the position of the central axis of the selected image section relative to the outer edges of the entire captured image, the position of the plate 3 relative to the optical sensor 6, and the angular position of the plate 3.

[0100] It should also be noted that the present invention allows inspection of the side surface of the container "C" even when the conveyor 2 is in a position where the container "C" falls into the field of view of the optical sensor 6. In this case, the control unit 7 captures the images of the rotating container "C", always selecting the same image section (i.e., the same position within the captured image) for each image, since the container "C" does not move along the feed direction of the conveyor 2.

[0101] In addition, the control unit 7 is configured to activate the optical sensor 6 at irregular intervals.

[0102] In other words, the possible combinations of angular positions that allow the activation of image acquisition are irregularly distributed between a minimum value (corresponding, for example, to the 0° rotation of plate 3) and a maximum value (corresponding, in this example, to the 360° rotation of plate 3).

[0103] In this way, the relative translational movement between the optical sensor 6 and the plate 3 generated by the simultaneous movement of the conveyor 2 can be taken into account.

[0104] A possible operating configuration of machine 1 is given below as a non-limiting example, which allows information on the entire lateral surface of the container “C” to be obtained particularly quickly and efficiently.

[0105] According to this example of the operating configuration, the rotating turntable is moved to make 15 to 20 revolutions per minute, that is, it can be moved to rotate 100° every second (which corresponds to about 16.5 revolutions per minute).

[0106] Likewise, each plate 3 can be rotated at a speed between 590 and 610 revolutions per minute, e.g. 600 revolutions per minute.

[0107] In this context, the plate 3 performs a complete rotation in 100 milliseconds (thereby exposing the entire lateral surface of the container “C” to the optical sensor 6).

[0108] So if the turntable is moved 100° every second, the container “C” makes one complete rotation while the turntable rotates 10° (angular image recording range).

[0109] Therefore, it is sufficient for the optical sensor 6 to have a field of view of 10° in order to be able to reconstruct the entire side surface of the container “C”.

[0110] The number and distribution of the predetermined combinations of angular positions in which the images are to be acquired is determined, for example, depending on the number of images to be acquired and the dimensions / shape of the container “C”.

[0111] So if 64 images are to be captured, optical sensor 6 must be activated every 1.5625 milliseconds.

[0112] As already highlighted, it is also possible to specify irregular intervals between one detection and the next in order to better take into account the movement of the rotating turntable 2.

[0113] Each of the captured images is uniquely associated with a precise angular position of both the turntable 2 and the plates 3 and is thus directly and uniquely linked to a specific section of the side surface of the container “C”.

[0114] It is therefore sufficient to place the individual images taken side by side in order to reconstruct the entire side surface and thus determine the exact position of the “point”.

[0115] Alternatively, the system analyzes the captured images or image sections individually to determine the position of the “point.”

[0116] According to a further aspect of the present invention, the machine comprises a pair of optical sensors 6 which are opposite to each other and arranged on opposite sides of the feed path.

[0117] As in Fig. As can be seen in more detail in Figure 2, the container “C” passes through the two optical sensors 6.

[0118] In this context, it is sufficient for each optical sensor 6 to detect only half of the total area of ​​the container “C”, thus further reducing the time required to collect all the useful information for identifying the position of the “point” on this area.

[0119] In addition, the field of view required for each optical sensor 6 is reduced in order to be able to perform the respective test.

[0120] With respect to the numerical example discussed above, each optical sensor 6 would be able to capture the entire image sequence in only 5° rotation of the turntable 2.

[0121] In this way, further possible distortion effects of the images resulting from them being taken when the container “C” is in different positions with respect to the optical sensor 6 are reduced.

[0122] Operationally, therefore, each optical sensor 6 captures a respective set of images which in total represent at least half of the entire lateral surface of the container “C”, with the control unit 7 flanking or simply analyzing the two sets of images to check the overall image.

[0123] To ensure correct analysis of the two sets, each of them may comprise images which, when placed side by side, represent more than half of the lateral surface of the container "C" (for example, in a range between 181° and 190°), so that the control unit 7 can use this slight superposition to check that no parts of the container "C" have been incorrectly inspected.

[0124] Functionally, the optical sensors 6 detect, as shown in Fig. can be seen, a first set 11a and a second set 11b of partial images, each representing slightly more than half of the total lateral surface of the container “C” (“slightly” means, for example, the area between 181° and 190° already mentioned).

[0125] The ends 12a, 12b of these sets 11a, 11b represent at least partially the same part of the lateral surface of the container "C," so that the control unit can reconstruct or simply analyze the overall image 11c by superimposing the overlapping area of ​​the two ends 12a, 12b. For example, if the location to be analyzed is located approximately in the center of the container, it will be captured in both images relating to these ends 12a and 12b.

[0126] It should be noted that reconstruction by flanking is not required since the control unit 7 is configured to analyze the two sets 11a and 11b individually without superimposing them.

[0127] It can be observed that each of the two sets 11a, 11b is preferably as shown in Fig. 4 and the above description. The control unit 7 is configured to calculate the orientation of the container "C" by analyzing the image(s) acquired by the optical sensor 6, depending on the position of the "point" present in the image relative to the angular position of the plate 3 at the end of the inspection.

[0128] Advantageously, the present invention achieves the proposed objectives by overcoming the disadvantages of the prior art by providing the user with a machine for inspecting the container "C" which operates quickly and efficiently, analyses the individual images or parts of images and reconstructs a representation of the entire lateral surface of the container "C" without requiring prior analysis and superimposition of the individual images acquired.

[0129] The present invention also relates to a method for inspecting a container “C”, which can be carried out particularly successfully with a machine having any combination of the technical features described above, to which reference is made in full below.

[0130] In particular, the method is carried out by providing a container “C” and moving it in a rotational and feed movement, for example by means of a plate 3 of a rotating turntable 2 or a linear motor.

[0131] In particular, the plates 3 and the conveyor 2 may be part of a machine 1 manufactured according to the above description.

[0132] During the movement of the container “C”, both the position of the plate 3 along the feed direction and the angular position of the plate 3 are recorded autonomously, separately and independently of each other.

[0133] The combination of this information makes it possible to accurately determine the effective orientation of container “C” at any time.

[0134] Then, the optical sensor 6 is activated at predetermined combinations of positions of the plate 3 along the feed direction and of the plate 3 with respect to the axis “Y” on which the container “C” is located, to capture a sequence of images each representing adjacent portions of the side surface of the container “C”.

[0135] In other words, whenever the conveyor 2 and the plate 3 assume certain angular positions, the acquisition of an image by the optical sensor 6 and the selection of the corresponding image section are activated as previously described, including the selection of the image section with the least perspective distortion.

[0136] The plurality of predetermined combinations thus determines the acquisition of an image sequence, which is analyzed by the control unit 7 individually or after reconstructing a representation of the lateral surface of the container "C". In particular, the control unit 7 flanks the images acquired by the optical sensor 6 without superimposing them, preferably as shown in Fig. 4 works.

[0137] Should the machine 1 comprise two optical sensors 6, the step of acquiring a sequence of representative images of respectively adjacent portions of a side surface of the container “C” may be performed by acquiring a first set 11a and a second set 11b of partial images each having ends 12a, 12b representing the same portion of the side surface of the container “C”.

[0138] In this context, the step of reconstructing the representation of the side surface of the container “C” is carried out by joining the partial images of each set 11a, 11b without superposition and by at least partially superimposing the respective ends 12a, 12b of the first set 12a and the second set 12b, as in Fig. shown.

[0139] In any case, it should be noted that such reconstruction by concatenation is not necessary since the control unit 7 is configured to analyze the two sets 11a and 11b individually without superimposing them.

[0140] Advantageously, such a method allows to reduce the time required for the reconstruction of the side surface of the container, since it is not necessary to search for the superimposable parts of each partial image, making it immediately available for subsequent processes, such as the identification of the "spot" and the subsequent application of a label.

Claims

[1] Machine for testing containers, comprising: - a conveyor (2) configured to move a sequence of containers along a feed path; - at least one plate (3) mounted on the conveyor (2) and configured to receive a container (C) and rotate it about an axis thereof along the feed path to impart a controlled rotational movement to the container (C) independently of the movement of the plate (3) along the feed path; - a first motor unit connected to the conveyor (2) for rotating it, and a second motor unit connected to the at least one plate (3) for rotating it about itself, wherein the first motor unit and the second motor unit are independent of each other and can be controlled separately; - a first position sensor (4) configured to detect a position of the plate (3) relative to the feed path; - at least one second angular position sensor (5) configured to detect an angular position of the at least one plate (3) with respect to the axis of the container (C); - a fixed optical sensor (6) arranged on one side of the feed path and facing the latter and configured to capture a sequence of images of a side surface of the container (C) during the combined rotational and translational movement along the feed path, the optical sensor (6) being the only sensor for inspecting the containers arranged on this side of the feed path and the optical sensor (6) being a camera; - a control unit (7) connected to the optical sensor (6) and to the first and second position sensors (5) and configured to receive a position signal of the plate (3) with respect to the feed path from the first sensor (4); to receive an angular position signal of the plate (3) with respect to the axis of the container (C) from the second sensor (5); to capture the sequence of images as a function of the position of the plate (3) along the feed path and the angular position of the plate (3) itself; to select a different part of each image as a function of the position of the plate (3) with respect to the feed path detected by the first sensor (4) and as a function of the angular position of the plate (3) with respect to the axis of the container (C), detected by the second sensor (5); to analyse each of the image sections selected for carrying out the test individually or to reconstruct a representation of the side surface of the container (C) by joining the image sections of the image sequence without superimposing them, and to analyse this representation to carry out the test; wherein the control unit (7) is further configured to calculate and select the part of each image corresponding to the projection of the image section onto a plane tangential to the container (C) and perpendicular to the central viewing axis (S) of the optical sensor (6) to achieve the least perspective distortion. [2] Machine according to claim 1, wherein the control unit (7) is configured to activate the optical sensor (6) in dependence on a plurality of predetermined combinations of positions of the plate (3) along the feed path and the angular position of the plate (3) itself. [3] Machine according to one of the preceding claims, wherein the control unit (7) is configured to activate different detection segments of the optical sensor (6) to detect a respective image segment, which is analyzed individually or flanked without superposition with subsequent image segments to define the representation of the lateral surface of the container (C). [4] Machine according to one of the preceding claims, wherein one or more of the image sections have the same width as the division of the total width of the image captured by the optical sensor (6) by the number of images captured by the optical sensor (6) itself. [5] Machine according to one of claims 1 to 3, wherein one or more of the image sections have a width greater than the division of the total width of the image captured by the optical sensor (6) by the number of images captured by the optical sensor (6) itself, so that the same characteristic of a container (C) is visible in different sections of successive images. [6] Machine according to one of the preceding claims, wherein the first motor unit connected to the conveyor (2) and the second motor unit connected to the at least one plate (3) are mechanically independent of each other. [7] A machine according to any preceding claim, wherein the conveyor (2) comprises a rotating turntable having a plurality of stations along its circumference in which the plates (3) are mounted; wherein the first position sensor (4) is configured to detect an angular position of the rotating turntable. [8] Machine according to one of the preceding claims, wherein the first angular position sensor (4) comprises an encoder coupled to the first motor unit and the second angular position sensor (5) comprises an encoder coupled to the second motor unit. [9] A machine according to any one of the preceding claims, wherein the conveyor (2) comprises a linear motor having a plurality of carriages movable along the feed path; wherein the rotary plate (3) is mounted on each of the carriages. [10] A machine according to any preceding claim, comprising a pair of opposed optical sensors arranged on opposite sides of the feed path. [11] A machine according to claim 10, wherein each optical sensor (6) is configured to acquire a sequence of images each representing adjacent portions of at least a respective half of the side surface of the container (C).

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