WO2021198797A1 - Machine for inspecting containers - Google Patents

Machine for inspecting containers Download PDF

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Publication number
WO2021198797A1
WO2021198797A1 PCT/IB2021/050831 IB2021050831W WO2021198797A1 WO 2021198797 A1 WO2021198797 A1 WO 2021198797A1 IB 2021050831 W IB2021050831 W IB 2021050831W WO 2021198797 A1 WO2021198797 A1 WO 2021198797A1
Authority
WO
WIPO (PCT)
Prior art keywords
container
plate
image
optical sensor
advancement path
Prior art date
Application number
PCT/IB2021/050831
Other languages
French (fr)
Inventor
Davide CAMPEDELLI
Simone Marcantoni
Christian MICHELINI
Original Assignee
Makro Labelling S.R.L.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Makro Labelling S.R.L. filed Critical Makro Labelling S.R.L.
Priority to EP21706711.5A priority Critical patent/EP4127685A1/en
Publication of WO2021198797A1 publication Critical patent/WO2021198797A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
    • G01N21/9009—Non-optical constructional details affecting optical inspection, e.g. cleaning mechanisms for optical parts, vibration reduction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
    • G01N21/9036—Investigating the presence of flaws or contamination in a container or its contents using arrays of emitters or receivers

Definitions

  • the present invention relates to the technical sector of machines for treating containers, preferably bottles, of various kinds and for example semi-transparent and opaque.
  • the present invention relates to a machine for inspecting the containers, arranged to operate when the latter are conveyed along an advancement path and a related method for detecting the orientation of the containers.
  • the present invention falls within the category of machines able to detect the entire lateral surface of containers in order to be able to analyse recognition signs, spots or the like that identify a particular arrangement of the container itself.
  • the identification of the orientation of the containers is particularly useful for the subsequent processing to be performed on the containers themselves, e.g. the labelling that must take place at some of the predefined areas of the bottle.
  • the present invention can be used for different purposes from the identification of the orientation of the containers such as, for example, for purposes connected with the analysis of the external characteristics of the container for assessing the conformity of the product with quality specifications dictated by the customer.
  • conveyors which can for example be made through rotating turntable conveyors or linear motors with movable carriages.
  • the conveyors comprise a plurality of rotating plates movable along an advancement path and onto which the containers to be treated are loaded.
  • rotating turntable conveyors they comprise a plurality of rotatable plates, positioned along the periphery of the turntable, onto which the bottles are loaded (one bottle per each plate).
  • the joint movement of the turntable and of the individual plates imparts to the bottles a roto-revolution movement (rotation about the axis of the plate and revolution about the axis of the turntable) which enables the progressive and sequential exposition of the entire lateral surface of the bottle to an appropriate detector.
  • a plurality of detectors is mounted on the turntable, each at a respective plate.
  • each detector inspects the entire lateral surface thereof in order to detect the position of a distinctive sign (commonly known as a “spot”) which can be, if for example the bottle is made of glass, the weld of the glass, an emblem arranged on the glass (at which, if desired, a label can for example be applied), or even other signs.
  • a distinctive sign commonly known as a “spot”
  • a control unit connected thereto processes the signal and associates it with the angle at which the plate is positioned at that precise moment.
  • the detectors are usually connected to the turntable in two preferred ways.
  • a first way envisages that there is a detector for each plate and it is fixed to the turntable (internally or externally) through a relevant bracket and turns solidly constrained to the turntable in order to follow the respective bottle during the rotation of the turntable.
  • a first drawback is connected to the fact that the presence of a plurality of sensors significantly complicates the structure of the turntable and increases the dimensions thereof.
  • a second technology which envisages there being at least one detector (preferably in the form of a camera) movable forwards and backwards along a predefined path following, at least for that portion of path, the bottle in rotation so as to film the lateral surface.
  • at least one detector preferably in the form of a camera
  • this known second technology has some drawbacks mainly connected with the fact that the detector moves externally to the turntable creating extra bulk at that area and with the fact that a specific and sometimes complex movement system needs to be provided.
  • the technical task underlying the present invention is to provide a machine for inspecting containers which obviates at least some of the drawbacks in the prior art as described above.
  • the set technical task and aims are substantially attained by a machine for inspecting containers, comprising the technical characteristics set out in one or more of the appended claims.
  • a machine for inspecting containers which comprises a conveyor, configured to move a succession of containers along an advancement path on which at least one plate is mounted configured to supportingly receive a container and to rotate about an axis thereof along the advancement path so as to impart to the container a rotation and simultaneous advancement motion.
  • the machine further comprises a first linear or angular position sensor configured to detect the position of the plate along the advancement direction and at least a second angular position sensor configured to detect an angular position of the at least one plate with respect to the axis of the container.
  • the movements of the container of advancement and rotation on itself are independent from one another as they are governed by independent motors (e.g. there are no mechanical or electronic movement relation cams) and independently controlled.
  • the conveyor can be presented in two embodiments that comprise a rotating turntable or a linear motor with carriages as will be better described below.
  • the machine further comprises at least one fixed optical sensor facing the advancement path and configured to acquire a succession of images representative of adjacent portions of a lateral surface of the container during its roto-revolution movement and a control unit configured to activate the acquisition of the images as a function simultaneously of the angular position of the rotating turntable and the angular position of the at least one plate.
  • optical sensor there is only one optical sensor at least with reference to the side in which it is installed with respect to the advancement path.
  • the claimed solution envisages selecting a different portion of each image as a function of the position of the plate with respect to the advancement path detected by the first sensor and as a function of the angular position of the plate with respect to the axis of the container detected by the second sensor.
  • the selection of a first portion of a first image is related to a first position of the plate along the advancement path and angular position on itself.
  • a second portion is obtained from a second image, subsequent to the first, and is related to a second position of the plate along the advancement path and angular position on itself.
  • the subject matter of the present invention is also a method for inspecting a container that is performed by arranging a container in a plate of a machine according to the present invention.
  • the position of the plate along the advancement and rotation direction of the plate about the axis of the container can be detected individually and separately.
  • the method therefore envisages activating the optical sensor at predetermined combinations of angular positions of the turntable and of the at least one plate, so as to acquire a succession of images representative of respective adjacent portions of the lateral surface of the container.
  • the method envisages selecting a different portion of each image as a function of the position of the plate with respect to the advancement path and as a function of the angular position of the plate with respect to the axis of the container.
  • the images of the succession of images are then analysed individually or flanked without superposition so as to reconstruct a representation of the lateral surface of the container.
  • the method proposed herein is particularly efficient, as the images acquired can be analysed individually or simply flanked without the need for the pre-analysis thereof in order to identify the superposition portions thereof.
  • the individual detection of the individual angular positions both of the turntable and of the plate guarantee that the entire lateral surface of the container is correctly inspected.
  • FIG. 1 schematically shows a machine according to the present invention
  • FIG. 2 shows a detail of a possible embodiment of the machine
  • FIG. 3a, 3b and 3c schematically show a graphical user interface on which the reconstruction of the lateral surface of the container can be displayed;
  • FIG. 6 shows an implementation detail of the machine according to the present invention.
  • reference number 1 generally indicates a machine for controlling the container “C”, to which reference will be made in the following present description simply as machine 1.
  • the machine 1 comprises a conveyor 2 for transporting containers “C” along an advancement path.
  • the latter can follow different shapes such as, for example, circular, oval, rectilinear or anything else not expressly identified herein as a function of the requirements.
  • the machine 1 further comprises at least one plate 3 rotatable about an axis of rotation ⁇ ” of the plate 3 which, preferably, coincides with the axis of rotation of the container “C”.
  • the present invention covers 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 illustrated in the appended figures) in which the conveyor is made with a linear motor having a plurality of carriages movable along the advancement path thanks to the electromagnetic field variation.
  • the rotating turntable is rotatable about an axis of rotation “X” of the turntable, which as it turns describes an advancement path in whose centre the axis of rotation “X” passes.
  • the at least one plate is arranged at a peripheral edge of the rotating turntable 2, so that the axis of rotation ⁇ ” of the plate 3 (parallel to the axis of rotation “X” of the turntable 2) intersects the advancement path.
  • the axis of rotation “Y” of the plate 3 moves along the advancement path.
  • each plate 3 defines a support surface for a container “C”.
  • the machine 1 comprises a plurality of plates 3 arranged circumferentially to the rotating turntable 2 at a predefined distance, identified as the pitch of the turntable, from one another.
  • Each plate is configured to rotate about its own axis of rotation “Y”, when it moves along the advancement path.
  • each plate 3 is mounted on a respective carriage movable along the advancement path.
  • the machine 1 further comprises a first angular position sensor 4 configured to detect an angular position of the rotating turntable 2 or the position of the plate 3 (or of the carriage on which the plate 3 is mounted) along the advancement path.
  • Such first sensor 4 therefore enables the exact orientation of the rotating turntable 2, or the position of the plate 3 along the advancement path, to be known at all times.
  • the machine 1 further comprises at least a second angular position sensor 5 configured to detect an angular position of the at least one plate 3 with respect to the axis of rotation “Y”.
  • the machine 1 comprises a second sensor 5 for each plate 3, so as to be able to know at all times the exact orientation of the individual plates 3 directly and independently from the detections performed by the first sensor 4 on the rotating turntable 2 or on the linear motor carriage.
  • the machine 1 comprises a first motor means that is associated with the rotating turntable 2 and a second motor means associated with the plate 3.
  • the first motor means is distinct and controllable independently from the second motor means and vice versa.
  • the second motor means is associated with each of them so that each plate 3 can be placed in rotation independently from each other plate 3 of the machine 1 and obviously independently from the rotation motion of the rotating turntable 2.
  • the first sensor 4 comprises an encoder coupled or integrated into the first motor means while the second sensor 5 comprises an encoder coupled or integrated into the second motor means.
  • the machine 1 can comprise a plurality of encoders coupled to respective plates 3, so as to be able to independently detect the angular position of the individual plates while they are made to rotate along the advancement path under the action of the second motor means.
  • the first sensor 4 is implemented directly in the electromagnetic control and command system of the carriage along the advancement path, whereas the second sensor 5 is made in the control system of the rotation of the plate 3 which can be performed through auxiliary carriages that act mechanically on the rotation of the plate 3 mounted on the main carriage as a function of the variation of the mutual distance controlled and/or through electric motors mounted directly on board the carriage and/or through other methods not expressly mentioned herein.
  • the machine 1 further comprises a fixed optical sensor 6 facing the advancement path and configured to acquire a succession of images representative of respective adjacent portions of a lateral surface of the container “C” during its rotation and advancement movement at a predefined portion of conveyor 2 (in the case of the turntable it is a predefined angular portion).
  • the optical sensor 6 is situated in a fixed position adjacent to the advancement path so as to have a field of vision that covers a predefined portion of the advancement path.
  • there is only one optical sensor 6 for one side, preferably external, of the conveyor 2 (only in the alternative embodiment of figure 2 there is an optical sensor 6 for each side: internal and external).
  • the optical sensor 6 can for example be made by means of a camera able to take a succession of photographs on distinct portions of the lateral surface of the container “C” in rotation.
  • the rotation and advancement motion imparted to the container “C” is such as to guarantee that during the crossing of the field of vision of the optical sensor 6 the entire lateral surface of the container “C” is exposed and can be correctly acquired.
  • the machine comprises a control unit 7 configured to activate the optical sensor 6 so as to acquire the succession of images as a function of the angular position of the rotating turntable 2 or of the plate 3 along the advancement direction and of the angular position of the at least one plate 3 with respect to the axis ⁇ ”.
  • control unit 7 receives from the first sensor 4 and from the second sensor 5 the information related to the angular position of the turntable 2 and of the plate 3 through respective electric signals representative of the position along the advancement path and of the angular position of the plate 3, and uses this information to activate the acquisition of the images by the optical sensor 6.
  • control unit 7 is configured to activate the optical sensor 6 as a function of a plurality of predetermined combinations of angular positions of the rotating turntable 2 and of the at least one plate 3.
  • a first portion 9a of a first image is related to a first position of the plate 3 along the advancement path and of the angular position on itself.
  • a second portion 9a is taken from a second image, subsequent to the first, and is related to a second position of the plate 3 along the advancement path and angular position on itself. And so forth...
  • the acquisition of the images that are superposed with one another becomes superfluous, as the control unit precisely knows the orientation of the container “C” (which is obtained from the combination of the angular position of the rotating turntable 2 or of the plate 3 along the advancement direction and of the plate 3 with respect to the axis ⁇ ” on which such container “C” rests) and therefore unambiguously identifies which portion of its lateral surface is being inspected.
  • control unit 7 is configured to individually analyse or to reconstruct a representation of the overall lateral surface of the container “C” by flanking without superposition the images of the succession of images to be analysed.
  • control unit can also be connected to or can directly comprise a graphical interface 8, on which both the field of vision of the optical sensor 6 and the progressive reconstruction of the lateral surface of the container “C” can be displayed.
  • Such reconstruction can for example take place according to the procedure shown in figure 4 (corresponding to what is represented in figures 3a-3c), wherein the overall image is reconstructed by sequentially aligning the partial images with each other in a row.
  • a first image portion 9a is used as a starting point and is positioned at a fixed lateral reference “A” (for example a right or left or central end of a display 8a of the graphical interface 8) and as a reference for the reconstruction of the image.
  • a fixed lateral reference “A” for example a right or left or central end of a display 8a of the graphical interface 8
  • control unit 7 receives in sequence the images acquired from the optical sensor 6 when the container “C” is in a succession of predefined positions and arranges them sequentially flanked to one another making the ends match without superposing them.
  • control unit 7 receives in sequence the images acquired from the optical sensor 6 when the container “C” is in a succession of predefined positions and analyses them individually without needing to superpose them to perform the total reconstruction of the lateral surface of the container “C”.
  • control unit 7 is configured to select a different portion of each image corresponding to a specific position of the plate 3 along the advancement path.
  • the set of said portions selected for each image define said reconstruction of the representation of the lateral surface of the container C or are analysed individually.
  • control unit 7 is configured for:
  • each image corresponds to a portion of visual field of the sensor 6.
  • figures 3a-3c represent a sequence of acquisition and selection of the images taken by the sensor 6, in which the container “C” is in advancement from right to left and simultaneously rotates on itself.
  • the broken parallel lines in the image at the top left of each figure represent the selected image portion.
  • the senor 6 detects the container “C” that enters into its visual field from the right and advances to the left and takes a series of photographs for each of which a different portion is selected that will contribute to composing the total image or that will be analysed.
  • control unit 7 associates the information related to the position of the container “C” along the advancement direction and the angular position of the container “C” on itself (information received from the position sensors 4 and 5) at that precise moment.
  • control unit is configured to select the first image portion between 0 and 100 pixel of the first image acquired, the second image portion between 101 and 200 pixel of the second image acquired, and so on.
  • the central extension axis of the selected portion of each image moves along the visual field of the sensor 6 and of the related images acquired as a function of the movement of the container “C” along the advancement path.
  • control unit 7 directly receives the portions of image (and does not select them) from the optical sensor 6 as different acquisition sectors of the same optical sensor 6 are activated so as to already acquire a respective image sector to be analysed individually or to be flanked without superposition with subsequent image sectors for defining said representation of the lateral surface of the container C.
  • such embodiment envisages acquiring the portions of image to be analysed or that are needed for composing the total representation of the lateral surface of the container C.
  • the acquisition sectors of the optical sensor 6 are activated sequentially as a function of the position of the container “C” along the advancement direction with respect to the position of the optical sensor 6 according to the same principle, mutatis mutandis, followed for the selection of the image portion described above.
  • each image portion (or acquisition sector) has a width equal to the subdivision of the total width of the image acquired by the optical sensor 6 by the number of images acquired by the optical sensor 6 itself.
  • each image portion has a width of 100 pixel (of the total of 14 images for obtaining 1400 pixel of the overall image).
  • control unit 7 is configured to select the portion of each image having the lowest perspective distortion with respect to the optical sensor 6.
  • the portion of each image having the lowest perspective distortion corresponds to the projection of the image portion on a plane tangential to the container “C” and perpendicular to a central viewing axis “S” of the optical sensor 6.
  • control unit 7 is configured to calculate the portion of each image having the lowest perspective distortion with reference to the plane tangential to the container “C” and perpendicular to the central axis “S” and, consequently, to select the portion of said image.
  • This system enables the entire image of the lateral surface of the container “C” to be reconstructed without superposition of the various portions of image (only juxtaposition), then analysing the entire image reconstructed for inspection. Alternatively, it is also possible to analyse every image portion individually for inspection (without performing the reconstruction).
  • one or more of said image portions has a larger width than the subdivision of the total width of the image acquired by the optical sensor 6 by the number of images acquired by the optical sensor 6 itself. In this way a same characteristic (“spot” or weld of the bottle or the like) of a container “C” is visible in various consecutive image portions.
  • control unit 7 does not perform the flanking and reconstruction of the entire image but analyses every individual image portion.
  • such embodiment enables less significant “spots” to be identified (such as, for example, the vertical weld of the glass of the bottle) which, because of some light reflection play on the container “C”, may not be detected in a single image portion. Therefore, by acquiring image portions having a larger width (with respect to the precise subdivision of the number of photos) it is possible to find the “spot” again in one or more consecutive image portions in order to be able to choose the image portion in which the “spot” is more significant with respect to other image portions thanks, for example, to a different (and more favourable) reflection of the light on the container “C”.
  • control unit 7 is configured to analyse every single image portion and to identify the “spot” within the chosen image portion. Furthermore, the control unit 7 can be configured to identify the position of the “spot” with respect to the entire lateral surface of the container “C” knowing the position of the central axis of the selected image portion with respect to the outer edges of the entire acquired image and knowing the position of the plate 3 with respect to the optical sensor 6 as well as the angular position of the plate 3.
  • the present invention enables an inspection of the lateral surface of the container “C” also when the conveyor 2 is stationary in a position in which the container “C” falls within the visual field of the optical sensor 6.
  • the control unit 7 acquires the images of the rotating container “C” always selecting for each image the same image portion (meaning the same position within the image taken) as the container “C” does not move along the advancement direction of the conveyor 2.
  • control unit 7 is configured to activate the optical sensor 6 at irregular intervals.
  • the possible combinations of angular positions which enable the acquisition of images to be activated are distributed in an irregular way between a minimum value (corresponding for example to the 0° rotation of the plate 3) and a maximum value (corresponding in this example to the 360° rotation of the plate 3).
  • a possible operating configuration of the machine 1 is provided hereinbelow by way of non-limiting example, which enables information to be obtained on the entire lateral surface of the container “C” particularly quickly and efficiently.
  • the rotating turntable is moved in order to perform from 15 to 20 revolutions per minute, e.g. it can be moved to rotate by 100° every second (corresponding to about 16.5 revolutions per minute).
  • each plate 3 can be moved in rotation at a speed comprised between 590 and 610 revolutions per minute, e.g. 600 revolutions per minute.
  • the plate 3 performs a complete revolution (therefore it exposes the entire lateral surface of the container “C” to the optical sensor 6) in 100 milliseconds.
  • the optical sensor 6 it is sufficient for the optical sensor 6 to have a 10° field of vision in order to be able to reconstruct the entire lateral surface of the container “C”.
  • the quantity and distribution of predetermined combinations of angular positions in which to acquire the images is determined for example as a function of the number of images to be acquired and the dimensions/shape of the container “C”.
  • Each of the images acquired is unambiguously associated with a precise angular position both of the turntable 2 and of the plates 3 and therefore directly connected unequivocally with a precise portion of the lateral surface of the container “C”.
  • the system individually analyses the images or portions of images acquired to identify the position of the “spot”.
  • the machine comprises a pair of optical sensors 6 opposing one another and arranged on opposite sides of the advancement path.
  • the container “C” therefore transits in between the two optical sensors 6.
  • each optical sensor 6 it is sufficient for each optical sensor 6 to only acquire half of the total surface of the container “C” further reducing the necessary time for obtaining all the useful information for identifying the position of the “spot” on such surface.
  • each optical sensor 6 would be able to acquire the entire sequence of images in just 5° rotation of the rotating turntable 2.
  • each optical sensor 6 therefore acquires a respective set of images that are representative overall of at least half the total lateral surface of the container “C”, the control unit 7 therefore provides to flank or simply analyse the two sets of images for inspecting the overall image.
  • each of them can comprise images that when flanked represent more than half of the lateral surface of the container “C” (for example in a range comprised between 181° and 190°), therefore the control unit 7 can exploit this slight superposition to check that there are no portions of the container “C” that haven’t been correctly inspected.
  • the optical sensors 6 respectively acquire a first set 11 a and a second set 11 b of partial images that each represent slightly more than half of the overall lateral surface of the container “C” (‘slightly’ means for example the already mentioned 181°-190°).
  • the ends 12a, 12b of such sets 11a, 11b represent at least partially the same portion of lateral surface of the container “C” and the control unit is therefore able to reconstruct or simply analyse the overall image 11c by superposing the superposition region of the two ends 12a, 12b. For example, if the spot to be analysed is located at about a “halfway” area of the container, it will be detected in both the images related to such ends 12a and 12b.
  • control unit 7 is configured to analyse the two sets 11a and 11b individually without superposing them.
  • each of the two sets 11a, 11b is preferably made according to what is illustrated in figure 4 and described above.
  • the control unit 7 is configured to calculate the orientation of the container “C” by analysing the image or the images detected by the optical sensor 6 as a function of the position of the “spot” present on the image related to the angular position of the plate 3 at the end of the inspection.
  • the present invention achieves the proposed objects, overcoming the disadvantages complained of in the prior art by providing the user with a machine for inspecting the container “C” that operates quickly and efficiently, analysing the individual images or image portions and reconstructing a representation of the entire lateral surface of the container “C” without requiring the prior analysis and superposition of the individual images acquired.
  • the subject matter of the present invention is also a method for inspecting a container “C” that can be performed particularly successfully by a machine that has any combination of the technical characteristics outlined above, which are referred to below in full.
  • the method is performed by providing a container “C” and moving it according to a rotation and advancement motion for example by means of a plate 3 of a rotating turntable 2 or linear motor.
  • the plates 3 and the conveyor 2 can be part of a machine 1 made according to what is described above.
  • both the position of the plate 3 along the advancement direction and the angular position of the plate 3 are detected autonomously, separately and independently.
  • the optical sensor 6 is activated at predetermined combinations of positions of the plate 3 along the advancement direction and of the plate 3 with respect to the axis ⁇ ” on which the container “C” is located, in order to acquire a succession of images representative of respective adjacent portions of the lateral surface of the container “C”.
  • the plurality of predetermined combinations therefore determines the acquisition of a sequence of images that are analysed by the control unit 7 individually or after the reconstruction of a representation of the lateral surface of the container “C”.
  • control unit 7 flanks without superposition the images acquired by the optical sensor 6, preferably operating according to what is illustrated in figure 4.
  • the step of acquiring a succession of representative images of respective adjacent portions of a lateral surface of the container “C” can be performed by acquiring a first set 11a and a second set 11b of partial images each having respective ends 12a, 12b representative of the same portion of lateral surface of the container “C”.
  • the step of reconstructing the representation of the lateral surface of the container “C” is performed by flanking without superposition the partial images of each set 11a, 11b and superposing at least partially the respective ends 12a, 12b of the first set 12a and of the second set 12b, as shown in figure 5.
  • control unit 7 is configured to analyse the two sets 11a and 11 b individually without superposing them.
  • such method enables the necessary times for the reconstruction of the lateral surface of the container, as it is not necessary to search for the superposable parts of each partial image, making it immediately available for the subsequent processes, e.g. for the identification of the “spot” and for the subsequent application of a label.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
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Abstract

A machine for inspecting containers (C) comprises a conveyor (2) and at least one plate (3) configured to supportingly receive a container (C), wherein the joint movement of the conveyor along an advancement path and of the plate (3) imparts to the container (C) a combined advancement and rotation movement on itself. The machine further comprises at least one fixed optical sensor (6) configured to acquire a succession of images representative of respective adjacent and not overlapping portions of a lateral surface of the container (C) during its movement and a control unit (7), associated with the optical sensor (6) that causes the acquisition of the succession of images as a function of the position of the plate (3) along the conveyor (2) and of the angular position of the at least one plate (3) with respect to the axis of the container (C).

Description

“Machine for inspecting containers”
Technical Field
The present invention relates to the technical sector of machines for treating containers, preferably bottles, of various kinds and for example semi-transparent and opaque.
In detail, the present invention relates to a machine for inspecting the containers, arranged to operate when the latter are conveyed along an advancement path and a related method for detecting the orientation of the containers.
In even more detail, the present invention falls within the category of machines able to detect the entire lateral surface of containers in order to be able to analyse recognition signs, spots or the like that identify a particular arrangement of the container itself.
The identification of the orientation of the containers is particularly useful for the subsequent processing to be performed on the containers themselves, e.g. the labelling that must take place at some of the predefined areas of the bottle.
Alternatively, it is to be noted that the present invention can be used for different purposes from the identification of the orientation of the containers such as, for example, for purposes connected with the analysis of the external characteristics of the container for assessing the conformity of the product with quality specifications dictated by the customer. Prior art
With particular reference to the sector of processing bottles, it is known to load them onto conveyors, which can for example be made through rotating turntable conveyors or linear motors with movable carriages.
In any case, the conveyors comprise a plurality of rotating plates movable along an advancement path and onto which the containers to be treated are loaded. For example, in relation to rotating turntable conveyors, they comprise a plurality of rotatable plates, positioned along the periphery of the turntable, onto which the bottles are loaded (one bottle per each plate).
During the normal use of the conveyor, the joint movement of the turntable and of the individual plates imparts to the bottles a roto-revolution movement (rotation about the axis of the plate and revolution about the axis of the turntable) which enables the progressive and sequential exposition of the entire lateral surface of the bottle to an appropriate detector.
In particular, according to the prior art, a plurality of detectors is mounted on the turntable, each at a respective plate.
During the rotation of the bottle on itself, each detector inspects the entire lateral surface thereof in order to detect the position of a distinctive sign (commonly known as a “spot”) which can be, if for example the bottle is made of glass, the weld of the glass, an emblem arranged on the glass (at which, if desired, a label can for example be applied), or even other signs. Once the sensor has detected the “spot” of the bottle, a control unit connected thereto processes the signal and associates it with the angle at which the plate is positioned at that precise moment.
In this way it is possible to know the orientation of the bottle on the plate and it is, for example, possible to apply a label in a desired point of the bottle.
The detectors are usually connected to the turntable in two preferred ways.
A first way envisages that there is a detector for each plate and it is fixed to the turntable (internally or externally) through a relevant bracket and turns solidly constrained to the turntable in order to follow the respective bottle during the rotation of the turntable.
However, this known technique implies some drawbacks.
In particular, a first drawback is connected to the fact that the presence of a plurality of sensors significantly complicates the structure of the turntable and increases the dimensions thereof.
Furthermore, a further drawback is connected with the fact that it is necessary to install a number of sensors equal to that of the plates of the rotating turntable.
Finally, it is to be noted that also the format change of the containers to be inspected during a work cycle is onerous and timely long to perform as the sensors need to be replaced or realigned with respect to the new container format.
Therefore, in the event of large turntables or that have many stations, a high number of detection sensors is required, thus increasing the final cost of the turntable both because of the costs connected with the sensors themselves and because of the costs connected with the structures that support them and their installation.
To overcome such disadvantages, a second technology is known which envisages there being at least one detector (preferably in the form of a camera) movable forwards and backwards along a predefined path following, at least for that portion of path, the bottle in rotation so as to film the lateral surface.
Also this known second technology has some drawbacks mainly connected with the fact that the detector moves externally to the turntable creating extra bulk at that area and with the fact that a specific and sometimes complex movement system needs to be provided.
Other technologies envisage that a single fixed camera is used facing the advancement path of the bottles and configured to take a succession of photographs that enable the entire surface of the bottle to be reconstructed.
Flowever, also this solution, although having a simpler construction, has disadvantages that make the performance implementation thereof poor.
In fact, the use of a single camera makes it necessary to have greater accuracy in the acquisition of images because of the angular displacement due to the roto-revolution movement of the bottle with respect to the fixed camera.
Therefore, in order to be able to guarantee that the entire surface of the bottle is reconstructed correctly, and that the “spot” is definitely detected, it is known to activate the camera so as to obtain images that are partially superposed with one another to then reconstruct the entire image of the lateral surface of the bottle.
However, this solution makes the processing of the collected information more laborious particularly in relation to the reconstruction to be performed.
In fact, it is necessary to pre-analyse the individual images acquired so as to identify and compare the individual superposition portions, only later reconstructing the whole image.
It is to be noted that the problems set out above in relation to the example of a rotating turntable conveyor also arise in the case of a linear motor conveyor with movable carriages to which the present invention relates.
Object of the present invention
In this context, the technical task underlying the present invention is to provide a machine for inspecting containers which obviates at least some of the drawbacks in the prior art as described above.
In particular, it is an object of the present invention to provide a machine for inspecting containers that is constructively simple and able to perform an inspection that is simultaneously quick and accurate.
The set technical task and aims are substantially attained by a machine for inspecting containers, comprising the technical characteristics set out in one or more of the appended claims.
According to the present invention, a machine for inspecting containers is shown, which comprises a conveyor, configured to move a succession of containers along an advancement path on which at least one plate is mounted configured to supportingly receive a container and to rotate about an axis thereof along the advancement path so as to impart to the container a rotation and simultaneous advancement motion.
The machine further comprises a first linear or angular position sensor configured to detect the position of the plate along the advancement direction and at least a second angular position sensor configured to detect an angular position of the at least one plate with respect to the axis of the container.
The movements of the container of advancement and rotation on itself are independent from one another as they are governed by independent motors (e.g. there are no mechanical or electronic movement relation cams) and independently controlled.
The conveyor can be presented in two embodiments that comprise a rotating turntable or a linear motor with carriages as will be better described below.
The machine further comprises at least one fixed optical sensor facing the advancement path and configured to acquire a succession of images representative of adjacent portions of a lateral surface of the container during its roto-revolution movement and a control unit configured to activate the acquisition of the images as a function simultaneously of the angular position of the rotating turntable and the angular position of the at least one plate.
There is only one optical sensor at least with reference to the side in which it is installed with respect to the advancement path.
It is to be noted that the claimed solution envisages selecting a different portion of each image as a function of the position of the plate with respect to the advancement path detected by the first sensor and as a function of the angular position of the plate with respect to the axis of the container detected by the second sensor.
In other words, the selection of a first portion of a first image is related to a first position of the plate along the advancement path and angular position on itself. A second portion is obtained from a second image, subsequent to the first, and is related to a second position of the plate along the advancement path and angular position on itself. And so forth... Advantageously, such solution prevents the need to superpose images for reconstructing a representation of the lateral surface of the container C, as the use of dedicated angular position sensors for the turntable and for the plate and the selection of different portions of image corresponding to predefined angular positions, enable the effective position of the container and its orientation along the advancement path to be always determined precisely and accurately and which angular position of the lateral surface was effectively photographed to be unambiguously identified.
The subject matter of the present invention is also a method for inspecting a container that is performed by arranging a container in a plate of a machine according to the present invention.
Subsequently, while the container is conveyed along the advancement direction, the position of the plate along the advancement and rotation direction of the plate about the axis of the container can be detected individually and separately.
The method therefore envisages activating the optical sensor at predetermined combinations of angular positions of the turntable and of the at least one plate, so as to acquire a succession of images representative of respective adjacent portions of the lateral surface of the container.
In particular, the method envisages selecting a different portion of each image as a function of the position of the plate with respect to the advancement path and as a function of the angular position of the plate with respect to the axis of the container.
The images of the succession of images are then analysed individually or flanked without superposition so as to reconstruct a representation of the lateral surface of the container.
Advantageously, the method proposed herein is particularly efficient, as the images acquired can be analysed individually or simply flanked without the need for the pre-analysis thereof in order to identify the superposition portions thereof.
At the same time, the individual detection of the individual angular positions both of the turntable and of the plate guarantee that the entire lateral surface of the container is correctly inspected.
The dependent claims, incorporated herein by reference, correspond to different embodiments of the invention.
Brief description of the figures
Further characteristics and advantages of the present invention will become more apparent from the general and thus non-limiting description of a preferred, but not exclusive, embodiment of a machine for inspecting containers, as illustrated in the accompanying drawings, in which:
- figure 1 schematically shows a machine according to the present invention;
- figure 2 shows a detail of a possible embodiment of the machine;
- figures 3a, 3b and 3c schematically show a graphical user interface on which the reconstruction of the lateral surface of the container can be displayed;
- figures 4, 5 show possible operating configurations of the machine, with particular reference to procedures for the reconstruction of the lateral surface;
- figure 6 shows an implementation detail of the machine according to the present invention.
Description of at least one preferred embodiment of the present invention
In the appended figures, reference number 1 generally indicates a machine for controlling the container “C”, to which reference will be made in the following present description simply as machine 1.
The machine 1 comprises a conveyor 2 for transporting containers “C” along an advancement path. The latter can follow different shapes such as, for example, circular, oval, rectilinear or anything else not expressly identified herein as a function of the requirements.
The machine 1 further comprises at least one plate 3 rotatable about an axis of rotation Ύ” of the plate 3 which, preferably, coincides with the axis of rotation of the container “C”.
The present invention covers 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 illustrated in the appended figures) in which the conveyor is made with a linear motor having a plurality of carriages movable along the advancement path thanks to the electromagnetic field variation.
According to the first embodiment of the conveyor 2 the rotating turntable is rotatable about an axis of rotation “X” of the turntable, which as it turns describes an advancement path in whose centre the axis of rotation “X” passes.
In particular, the at least one plate is arranged at a peripheral edge of the rotating turntable 2, so that the axis of rotation Ύ” of the plate 3 (parallel to the axis of rotation “X” of the turntable 2) intersects the advancement path. In other words, during the rotation of the rotating turntable 2, the axis of rotation “Y” of the plate 3 moves along the advancement path.
Additionally, each plate 3 defines a support surface for a container “C”. Preferably, the machine 1 comprises a plurality of plates 3 arranged circumferentially to the rotating turntable 2 at a predefined distance, identified as the pitch of the turntable, from one another.
Each plate is configured to rotate about its own axis of rotation “Y”, when it moves along the advancement path.
In this way the joint movement of the rotating turntable 2 and of the plate 3 enables a roto-revolution motion to be imparted to the container “C” housed therein (rotation about the axis of rotation “Y” of the plate 3 and revolution about the axis of rotation “X” of the rotating turntable 2).
In the case of the embodiment of the linear motor, each plate 3 is mounted on a respective carriage movable along the advancement path.
The machine 1 further comprises a first angular position sensor 4 configured to detect an angular position of the rotating turntable 2 or the position of the plate 3 (or of the carriage on which the plate 3 is mounted) along the advancement path.
Such first sensor 4 therefore enables the exact orientation of the rotating turntable 2, or the position of the plate 3 along the advancement path, to be known at all times.
The machine 1 further comprises at least a second angular position sensor 5 configured to detect an angular position of the at least one plate 3 with respect to the axis of rotation “Y”.
Preferably, the machine 1 comprises a second sensor 5 for each plate 3, so as to be able to know at all times the exact orientation of the individual plates 3 directly and independently from the detections performed by the first sensor 4 on the rotating turntable 2 or on the linear motor carriage.
In particular, in the case of the rotating turntable, the machine 1 comprises a first motor means that is associated with the rotating turntable 2 and a second motor means associated with the plate 3. Preferably, the first motor means is distinct and controllable independently from the second motor means and vice versa.
Should there be more plates 3, the second motor means is associated with each of them so that each plate 3 can be placed in rotation independently from each other plate 3 of the machine 1 and obviously independently from the rotation motion of the rotating turntable 2.
According to such aspect, the first sensor 4 comprises an encoder coupled or integrated into the first motor means while the second sensor 5 comprises an encoder coupled or integrated into the second motor means. In particular, the machine 1 can comprise a plurality of encoders coupled to respective plates 3, so as to be able to independently detect the angular position of the individual plates while they are made to rotate along the advancement path under the action of the second motor means. 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 advancement path, whereas the second sensor 5 is made in the control system of the rotation of the plate 3 which can be performed through auxiliary carriages that act mechanically on the rotation of the plate 3 mounted on the main carriage as a function of the variation of the mutual distance controlled and/or through electric motors mounted directly on board the carriage and/or through other methods not expressly mentioned herein.
The machine 1 further comprises a fixed optical sensor 6 facing the advancement path and configured to acquire a succession of images representative of respective adjacent portions of a lateral surface of the container “C” during its rotation and advancement movement at a predefined portion of conveyor 2 (in the case of the turntable it is a predefined angular portion).
In other words, the optical sensor 6 is situated in a fixed position adjacent to the advancement path so as to have a field of vision that covers a predefined portion of the advancement path. As can be seen in the appended figures, there is only one optical sensor 6 for one side, preferably external, of the conveyor 2 (only in the alternative embodiment of figure 2 there is an optical sensor 6 for each side: internal and external). The optical sensor 6 can for example be made by means of a camera able to take a succession of photographs on distinct portions of the lateral surface of the container “C” in rotation.
The rotation and advancement motion imparted to the container “C” is such as to guarantee that during the crossing of the field of vision of the optical sensor 6 the entire lateral surface of the container “C” is exposed and can be correctly acquired.
To synchronise the acquisition of the images during the rotation of the containers “C” the machine comprises a control unit 7 configured to activate the optical sensor 6 so as to acquire the succession of images as a function of the angular position of the rotating turntable 2 or of the plate 3 along the advancement direction and of the angular position of the at least one plate 3 with respect to the axis Ύ”.
In other words, the control unit 7 receives from the first sensor 4 and from the second sensor 5 the information related to the angular position of the turntable 2 and of the plate 3 through respective electric signals representative of the position along the advancement path and of the angular position of the plate 3, and uses this information to activate the acquisition of the images by the optical sensor 6.
In particular, the control unit 7 is configured to activate the optical sensor 6 as a function of a plurality of predetermined combinations of angular positions of the rotating turntable 2 and of the at least one plate 3.
In other words, the selection of a first portion 9a of a first image is related to a first position of the plate 3 along the advancement path and of the angular position on itself. A second portion 9a is taken from a second image, subsequent to the first, and is related to a second position of the plate 3 along the advancement path and angular position on itself. And so forth...
In this way, the acquisition of the images that are superposed with one another becomes superfluous, as the control unit precisely knows the orientation of the container “C” (which is obtained from the combination of the angular position of the rotating turntable 2 or of the plate 3 along the advancement direction and of the plate 3 with respect to the axis Ύ” on which such container “C” rests) and therefore unambiguously identifies which portion of its lateral surface is being inspected.
In particular, the control unit 7 is configured to individually analyse or to reconstruct a representation of the overall lateral surface of the container “C” by flanking without superposition the images of the succession of images to be analysed.
As can be observed in figures 3a-3c, the control unit can also be connected to or can directly comprise a graphical interface 8, on which both the field of vision of the optical sensor 6 and the progressive reconstruction of the lateral surface of the container “C” can be displayed. Such reconstruction can for example take place according to the procedure shown in figure 4 (corresponding to what is represented in figures 3a-3c), wherein the overall image is reconstructed by sequentially aligning the partial images with each other in a row.
In particular, a first image portion 9a is used as a starting point and is positioned at a fixed lateral reference “A” (for example a right or left or central end of a display 8a of the graphical interface 8) and as a reference for the reconstruction of the image.
Then, a second image portion 9b and a third image portion 9c are flanked to such first image 1a in subsequent steps.
Therefore, in general, the control unit 7 receives in sequence the images acquired from the optical sensor 6 when the container “C” is in a succession of predefined positions and arranges them sequentially flanked to one another making the ends match without superposing them. Alternatively, the control unit 7 receives in sequence the images acquired from the optical sensor 6 when the container “C” is in a succession of predefined positions and analyses them individually without needing to superpose them to perform the total reconstruction of the lateral surface of the container “C”.
In accordance with 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 advancement path. The set of said portions selected for each image define said reconstruction of the representation of the lateral surface of the container C or are analysed individually.
In other words, the control unit 7 is configured for:
- receive the images detected by the optical sensor 6;
- select a portion (or slice) of each image corresponding to a specific position of the plate 3 along the advancement path; - flank without superposition the portions selected so as to compose the entire image of the lateral surface of the container “C” or individually analyse said selected portions.
It is to be noted that the portion of each image corresponds to a portion of visual field of the sensor 6.
In detail figures 3a-3c represent a sequence of acquisition and selection of the images taken by the sensor 6, in which the container “C” is in advancement from right to left and simultaneously rotates on itself. The broken parallel lines in the image at the top left of each figure represent the selected image portion.
In practice, the sensor 6 detects the container “C” that enters into its visual field from the right and advances to the left and takes a series of photographs for each of which a different portion is selected that will contribute to composing the total image or that will be analysed.
In any case, it is to be noted that, with each image portion detected, the control unit 7 associates the information related to the position of the container “C” along the advancement direction and the angular position of the container “C” on itself (information received from the position sensors 4 and 5) at that precise moment.
In other words, there is a precise relationship between the selected image portion with respect to the position of the plate 3 along the advancement path.
For example, by hypothesizing an optical sensor 6 with 1400-pixel width and portions of image with 100 pixel each and wanting to acquire 14 images, the control unit is configured to select the first image portion between 0 and 100 pixel of the first image acquired, the second image portion between 101 and 200 pixel of the second image acquired, and so on.
In particular, the central extension axis of the selected portion of each image moves along the visual field of the sensor 6 and of the related images acquired as a function of the movement of the container “C” along the advancement path.
In one embodiment, the control unit 7 directly receives the portions of image (and does not select them) from the optical sensor 6 as different acquisition sectors of the same optical sensor 6 are activated so as to already acquire a respective image sector to be analysed individually or to be flanked without superposition with subsequent image sectors for defining said representation of the lateral surface of the container C.
In other words, such embodiment envisages acquiring the portions of image to be analysed or that are needed for composing the total representation of the lateral surface of the container C.
The acquisition sectors of the optical sensor 6 are activated sequentially as a function of the position of the container “C” along the advancement direction with respect to the position of the optical sensor 6 according to the same principle, mutatis mutandis, followed for the selection of the image portion described above.
In any case, as already set out above, each image portion (or acquisition sector) has a width equal to the subdivision of the total width of the image acquired by the optical sensor 6 by the number of images acquired by the optical sensor 6 itself. To return to the previous example, each image portion has a width of 100 pixel (of the total of 14 images for obtaining 1400 pixel of the overall image).
According to an aspect of the present invention, the control unit 7 is configured to select the portion of each image having the lowest perspective distortion with respect to the optical sensor 6.
As represented in figure 6, the portion of each image having the lowest perspective distortion corresponds to the projection of the image portion on a plane tangential to the container “C” and perpendicular to a central viewing axis “S” of the optical sensor 6.
In other words, the control unit 7 is configured to calculate the portion of each image having the lowest perspective distortion with reference to the plane tangential to the container “C” and perpendicular to the central axis “S” and, consequently, to select the portion of said image.
In this way, it is advantageously possible to select the view with lowest deformation or distortion of a certain image portion considering the angular deviation of the container “C” with respect to the central axis “S”.
This system enables the entire image of the lateral surface of the container “C” to be reconstructed without superposition of the various portions of image (only juxtaposition), then analysing the entire image reconstructed for inspection. Alternatively, it is also possible to analyse every image portion individually for inspection (without performing the reconstruction).
In an embodiment that is part of the present invention, one or more of said image portions has a larger width than the subdivision of the total width of the image acquired by the optical sensor 6 by the number of images acquired by the optical sensor 6 itself. In this way a same characteristic (“spot” or weld of the bottle or the like) of a container “C” is visible in various consecutive image portions.
In this case, the control unit 7 does not perform the flanking and reconstruction of the entire image but analyses every individual image portion.
Advantageously, such embodiment enables less significant “spots” to be identified (such as, for example, the vertical weld of the glass of the bottle) which, because of some light reflection play on the container “C”, may not be detected in a single image portion. Therefore, by acquiring image portions having a larger width (with respect to the precise subdivision of the number of photos) it is possible to find the “spot” again in one or more consecutive image portions in order to be able to choose the image portion in which the “spot” is more significant with respect to other image portions thanks, for example, to a different (and more favourable) reflection of the light on the container “C”.
In this latter case, the control unit 7 is configured to analyse every single image portion and to identify the “spot” within the chosen image portion. Furthermore, the control unit 7 can be configured to identify the position of the “spot” with respect to the entire lateral surface of the container “C” knowing the position of the central axis of the selected image portion with respect to the outer edges of the entire acquired image and knowing the position of the plate 3 with respect to the optical sensor 6 as well as the angular position of the plate 3.
It is also to be noted that the present invention enables an inspection of the lateral surface of the container “C” also when the conveyor 2 is stationary in a position in which the container “C” falls within the visual field of the optical sensor 6. In this case, the control unit 7 acquires the images of the rotating container “C” always selecting for each image the same image portion (meaning the same position within the image taken) as the container “C” does not move along the advancement direction of the conveyor 2.
Furthermore, the control unit 7 is configured to activate the optical sensor 6 at irregular intervals.
In other words, the possible combinations of angular positions which enable the acquisition of images to be activated are distributed in an irregular way between a minimum value (corresponding for example to the 0° rotation of the plate 3) and a maximum value (corresponding in this example to the 360° rotation of the plate 3).
In this way, it is possible to consider the relative translation movement between the optical sensor 6 and the plate 3 generated by the simultaneous movement of the conveyor 2.
A possible operating configuration of the machine 1 is provided hereinbelow by way of non-limiting example, which enables information to be obtained on the entire lateral surface of the container “C” particularly quickly and efficiently.
According to such example of the operating configuration, the rotating turntable is moved in order to perform from 15 to 20 revolutions per minute, e.g. it can be moved to rotate by 100° every second (corresponding to about 16.5 revolutions per minute). Likewise, each plate 3 can be moved in rotation at a speed comprised between 590 and 610 revolutions per minute, e.g. 600 revolutions per minute.
In this context, the plate 3 performs a complete revolution (therefore it exposes the entire lateral surface of the container “C” to the optical sensor 6) in 100 milliseconds.
Consequently, if the turntable is moved by 100° every second, the container “C” performs a complete revolution while the turntable rotates by 10° (angular image acquisition portion).
Therefore, it is sufficient for the optical sensor 6 to have a 10° field of vision in order to be able to reconstruct the entire lateral surface of the container “C”.
The quantity and distribution of predetermined combinations of angular positions in which to acquire the images is determined for example as a function of the number of images to be acquired and the dimensions/shape of the container “C”.
Therefore, if 64 images are to be acquired, it will be necessary to activate the optical sensor 6 every 1.5625 milliseconds.
As already highlighted, it is also possible to pre-set irregular intervals between one acquisition and the subsequent one so as to keep better consideration of the movement of the rotating turntable 2.
Each of the images acquired is unambiguously associated with a precise angular position both of the turntable 2 and of the plates 3 and therefore directly connected unequivocally with a precise portion of the lateral surface of the container “C”.
It is therefore sufficient to flank the individual images acquired in order to reconstruct the entire lateral surface, thus enabling the exact position of the “spot” to be identified.
Alternatively, the system individually analyses the images or portions of images acquired to identify the position of the “spot”.
According to a further aspect of the present invention, the machine comprises a pair of optical sensors 6 opposing one another and arranged on opposite sides of the advancement path.
As can be observed in more detail in figure 2, the container “C” therefore transits in between the two optical sensors 6.
In this context it is sufficient for each optical sensor 6 to only acquire half of the total surface of the container “C” further reducing the necessary time for obtaining all the useful information for identifying the position of the “spot” on such surface.
Furthermore, the range of the field of vision necessary for each optical sensor 6 in order to be able to perform its respective inspection is reduced. In relation to the numerical example discussed above, each optical sensor 6 would be able to acquire the entire sequence of images in just 5° rotation of the rotating turntable 2.
In this way, any further possible distortion effects of the images due to the fact that they are acquired when the container “C” is in different positions with respect to the optical sensor 6 are reduced further.
Operatively, each optical sensor 6 therefore acquires a respective set of images that are representative overall of at least half the total lateral surface of the container “C”, the control unit 7 therefore provides to flank or simply analyse the two sets of images for inspecting the overall image.
To guarantee the correct analysis of the two sets, each of them can comprise images that when flanked represent more than half of the lateral surface of the container “C” (for example in a range comprised between 181° and 190°), therefore the control unit 7 can exploit this slight superposition to check that there are no portions of the container “C” that haven’t been correctly inspected.
Operatively, as can be observed in figure 5, the optical sensors 6 respectively acquire a first set 11 a and a second set 11 b of partial images that each represent slightly more than half of the overall lateral surface of the container “C” (‘slightly’ means for example the already mentioned 181°-190°). The ends 12a, 12b of such sets 11a, 11b represent at least partially the same portion of lateral surface of the container “C” and the control unit is therefore able to reconstruct or simply analyse the overall image 11c by superposing the superposition region of the two ends 12a, 12b. For example, if the spot to be analysed is located at about a “halfway” area of the container, it will be detected in both the images related to such ends 12a and 12b.
It is to be noted that reconstruction by flanking is not necessary as the control unit 7 is configured to analyse the two sets 11a and 11b individually without superposing them.
It is observed that each of the two sets 11a, 11b is preferably made according to what is illustrated in figure 4 and described above.
The control unit 7 is configured to calculate the orientation of the container “C” by analysing the image or the images detected by the optical sensor 6 as a function of the position of the “spot” present on the image related to the angular position of the plate 3 at the end of the inspection. Advantageously, the present invention achieves the proposed objects, overcoming the disadvantages complained of in the prior art by providing the user with a machine for inspecting the container “C” that operates quickly and efficiently, analysing the individual images or image portions and reconstructing a representation of the entire lateral surface of the container “C” without requiring the prior analysis and superposition of the individual images acquired.
The subject matter of the present invention is also a method for inspecting a container “C” that can be performed particularly successfully by a machine that has any combination of the technical characteristics outlined above, which are referred to below in full.
In particular, the method is performed by providing a container “C” and moving it according to a rotation and advancement motion for example by means of a plate 3 of a rotating turntable 2 or linear motor.
In particular, the plates 3 and the conveyor 2 can be part of a machine 1 made according to what is described above.
During the movement of the container “C”, both the position of the plate 3 along the advancement direction and the angular position of the plate 3 are detected autonomously, separately and independently.
The combination of such information makes it possible to find out precisely at all times the effective orientation of the container “C”.
Then the optical sensor 6 is activated at predetermined combinations of positions of the plate 3 along the advancement direction and of the plate 3 with respect to the axis Ύ” on which the container “C” is located, in order to acquire a succession of images representative of respective adjacent portions of the lateral surface of the container “C”.
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 portion of image as previously described are activated, including the part of selecting the image portion with the lowest perspective distortion.
The plurality of predetermined combinations therefore determines the acquisition of a sequence of images that are analysed by the control unit 7 individually or after the reconstruction of a representation of the lateral surface of the container “C”.
In particular, the control unit 7 flanks without superposition the images acquired by the optical sensor 6, preferably operating according to what is illustrated in figure 4.
Furthermore, should the machine 1 comprise two optical sensors 6, the step of acquiring a succession of representative images of respective adjacent portions of a lateral surface of the container “C” can be performed by acquiring a first set 11a and a second set 11b of partial images each having respective ends 12a, 12b representative of the same portion of lateral surface of the container “C”.
In this context, the step of reconstructing the representation of the lateral surface of the container “C” is performed by flanking without superposition the partial images of each set 11a, 11b and superposing at least partially the respective ends 12a, 12b of the first set 12a and of the second set 12b, as shown in figure 5.
In any case, it is to be noted that such reconstruction by flanking is not necessary as the control unit 7 is configured to analyse the two sets 11a and 11 b individually without superposing them.
Advantageously, such method enables the necessary times for the reconstruction of the lateral surface of the container, as it is not necessary to search for the superposable parts of each partial image, making it immediately available for the subsequent processes, e.g. for the identification of the “spot” and for the subsequent application of a label.

Claims

1. A machine for inspecting containers, comprising:
- a conveyor (2), configured to move a succession of containers along an advancement path;
- at least one plate (3), mounted on the conveyor (2), configured to supportingly receive a container (C) and to rotate about an axis thereof along the advancement path so as to impart to said container (C) a controlled rotation motion regardless of the movement of the plate (3) along the advancement path;
- a first motor means associated with the conveyor (2) to make it rotate and a second motor means associated with the at least one plate (3) to make it rotate on itself, wherein said first motor means and said second motor means are independent from one another and can be controlled separately;- a first position sensor (4) configured to detect a position of the plate (3) with respect to the advancement path;
- at least a 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);
- one fixed optical sensor (6) arranged at one side of the advancement path and oriented to face it and configured to acquire a succession of images of a lateral surface of the container (C) during the combined rotation and displacement movement along the advancement path; said optical sensor (6) being the only sensor for inspecting the containers arranged at said side of the advancement path;
- a control unit (7) associated with the optical sensor (6) and with the first and second position sensor (5) and configured to: receive a position signal of the plate (3) with respect to the advancement path from said first sensor (4); receive an angular position signal of the plate (3) with respect to the axis of the container (C) from said second sensor (5); acquire said succession of images as a function of the position of the plate (3) along the advancement path and the angular position of the plate (3) itself; select a different portion of each image as a function of the position of the plate (3) with respect to the advancement path detected by said 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 said second sensor (5); individually analyse each of said image portions selected for performing said inspection, or reconstruct a representation of the lateral surface of the container (C) by flanking without superposition the image portions of said succession of images and analyse said representation for performing said inspection.
2. The machine according to claim 1 , wherein the control unit (7) is configured to activate the optical sensor (6) as a function of a plurality of predetermined combinations of positions of the plate (3) along the advancement path and the angular position of the plate (3) itself.
3. The machine according to any one of the preceding claims, wherein the control unit (7) is configured to select the portion of each image having the lowest perspective distortion with respect to the optical sensor (6); said portion of each image having the lowest perspective distortion corresponding to the projection of the image portion on a plane tangential to the container (C) and perpendicular to a central viewing axis (S) of the optical sensor (6).
4. The machine according to any one of the preceding claims, wherein the control unit (7) is configured to activate different acquisition sectors of the optical sensor (6) so as to acquire a respective image sector to be analysed individually or to be flanked without superposition with subsequent image sectors for defining said representation of the lateral surface of the container (C).
5. The machine according to any one of the preceding claims, wherein one or more of said image portions has the same width as the subdivision of the total width of the image acquired by the optical sensor (6) by the number of images acquired by the optical sensor (6) itself.
6. The machine according to any one of claims 1 to 4, wherein one or more of said image portions has a larger width than the subdivision of the total width of the image acquired by the optical sensor (6) by the number of images acquired by the optical sensor (6) itself so that the same characteristic of a container (C) is visible in various portions of consecutive images.
7. The machine according to any one of the preceding claims, wherein the first motor means associated with the conveyor (2) and the second motor means associated with the at least one plate (3) are mechanically unconstrained from one another.
8. The machine according to any one of the preceding claims, wherein said conveyor (2) comprises a rotating turntable having a plurality of stations along the periphery thereof in which said plates (3) are mounted; said first position sensor (4) being configured to detect an angular position of said rotating turntable.
9. The machine according to any one of the preceding claims, said first angular position sensor (4) comprising an encoder coupled to the first motor means and said second angular position sensor (5) comprising an encoder coupled to the second motor means.
10. The machine according to any one of the preceding claims, wherein said conveyor (2) comprises a linear motor having a plurality of carriages movable along said advancement path; said rotating plate (3) being mounted on each of said carriages.
11. The machine according to any one of the preceding claims, comprising a pair of opposing optical sensors arranged on opposite sides of the advancement path.
12. The machine according to claim 11 , wherein each optical sensor (6) is configured to acquire a succession of images representative of respective adjacent portions of at least one respective half of the lateral surface of the container (C).
13. A method for inspecting a container (C), comprising the steps of:
- arranging and moving a container (C) in a plate (3) of a machine for inspecting containers, preferably a machine according to any one of the preceding claims wherein the movement of the container (C) along the advancement path is independent and can be controlled separately from the rotation movement of the plate (3) on itself;
- continuously detecting a position of the conveyor (2) along the advancement path;
- continuously detecting an angular position of the plate (3);
- acquiring, through a single fixed optical sensor (6) arranged at a side of the advancement path a succession of images representative of respective adjacent and not overlapping portions of a lateral surface of the container (C) as a function of the position of the plate (3) along the advancement path and the angular position (3) thereof;
- selecting a different portion of each image as a function of the position of the plate (3) with respect to the advancement path and as a function of the angular position of the plate (3) with respect to the axis of the container (C); - individually analysing each of said image portions selected for performing said inspection, or reconstructing a representation of the lateral surface of the container (C) by flanking without superposition the image portions of the succession of images and analysing said representation for performing said inspection.
14. The method according to claim 13, comprising the step of acquiring said succession of images as a function of a plurality of predetermined combinations of positions of the plate (3) along the advancement path and the angular position of the plate (3) itself.
15. The method according to one of claims 13 to 14, comprising the step of selecting the portion of each image having the lowest perspective distortion with respect to the optical sensor (6); said portion of each image having the lowest perspective distortion corresponding to the projection of the image portion on a plane tangential to the container (C) and perpendicular to a central viewing axis of the optical sensor (6).
16. The method according to any one of claims 13 to 15, wherein the acquisition step envisages sequentially activating different acquisition sectors of the optical sensor (6) so as to acquire a respective image sector to be analysed individually or to be flanked without superposition with subsequent image sectors for forming said representation of the lateral surface of the container (C).
17. The method according to one of claims 13 to 16, wherein the step of acquiring a succession of representative images of respective adjacent portions of a lateral surface of the container (C) is performed by acquiring a first set (11a) and a second set (11b) of partial images respectively corresponding substantially to different halves of the lateral surface of the container (C).
PCT/IB2021/050831 2020-03-31 2021-02-02 Machine for inspecting containers WO2021198797A1 (en)

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US5007096A (en) * 1987-02-18 1991-04-09 Hajime Industries Ltd. Object inspection apparatus
EP0872724A2 (en) * 1997-03-18 1998-10-21 Logics & Control S.n.c. di Lottici Marco e C. Method and apparatus for the external inspection of containers
US20070115467A1 (en) * 2005-11-23 2007-05-24 Owens-Brockway Glass Container Apparatus and method for ensuring rotation of a container during inspection
EP1804055A1 (en) * 2005-12-30 2007-07-04 KRONES Aktiengesellschaft Device for inspecting labels on containers
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