Label feeding system provided with recovery mode and verification mode of sensor device

Abstract

A label feed system (15) for a labeling machine (1) is described, the label feed system (15) comprising: a sensor device comprising an optical sensor (17) having a fixed field of view (FV); a feed roller (11) for longitudinally feeding a web (4) of labeling material along a feed path (P) and through said field of view (FV), the web (4) comprising a plurality of longitudinally connected labels (3), each label (3) having a plurality of longitudinal portions and an aesthetic feature (AF) arranged at a determined longitudinal portion; and a reference member (16) fixed with respect to the feed path (P) and the field of view (FV) and arranged within the field of view (FV); the sensor device is configured to operate in a production mode according to which, for each label (3), the optical sensor (17) sequentially acquires an image (I) of the field of view (FV) at said determined longitudinal portion to detect a linear distance between the respective aesthetic feature (AF) and the reference member (16); the sensor device is further configured to operate in a recovery mode according to which the optical sensor (17) acquires a plurality of images (I1, I2, I3) of the field of view (FV) for searching for an aesthetic feature (AF), where each image (I1; i2; i3) of the plurality of images comprises at least one longitudinal portion which is different from the other images (I2, I3; i1, I3; i1, I2) to inspect all different longitudinal portions cumulatively by a single label (3) or by a plurality of labels (3a, 3b, 3c) during the recovery mode.

Description

Technical Field

[0001] The present invention relates to a label feeding system for a labelling machine arranged to label containers, such as bottles, cans, vials or the like, suitable for containing pourable products, preferably pourable food products. Background Art

[0002] Labelling machines are known which are usually used to prepare labels, in particular labels obtained from a web of labelling material, convey and apply them to containers, such as bottles, vials, cans or the like, intended to be filled with pourable products, in particular pourable foodstuffs.

[0003] Such labeling machines typically operate using the well-known adhesive labels which are cut from a web at appropriate lengths, sprayed with glue, and then applied to the container.

[0004] In other embodiments, the labeling machine may operate using so-called "sleeve labels" that are cut from a heat shrink film web, applied to the container with a certain gap, and then heated in an oven, causing the label to shrink and perfectly adhere to the side of the container.

[0005] Regardless of the type of label used, known labeling machines typically include: - a turntable rotatable about a vertical axis and configured to convey a plurality of containers along a horizontal curved labeling path; and a labelling module arranged relative to the periphery of the carousel (ie radially relative to the aforementioned vertical axis) and configured to prepare, transport and feed a plurality of labels to the carousel at an application station in order to apply these labels to the respective containers.

[0006] Typically, the labeling module mainly includes: - at least one supporting shaft, on which the web of labelling material is initially wound in the form of a reel; - a label feed system for feeding a web of labelling material along a feed path, which typically comprises feed rollers for unwinding the web from a reel and advancing it along the feed path; - a cutting unit for repeatedly cutting the web at a cutting station in order to separate a series of labels from the web itself; and - a label transfer device, such as a known vacuum drum arranged at the periphery of the carousel, configured to receive, retain and advance each previously cut label at the application station and to feed each label to the carousel.

[0007] In the case of using adhesive labels, the labeling module also includes a glue roller arranged at the periphery of the vacuum drum, for spraying glue sequentially onto each label held and conveyed by the drum itself.

[0008] It is known in the art that there is a need for: - continuously monitoring the positioning of the web of labelling material as it is unwound from the respective reel; and - Correction of the positioning in case deviations from the nominal positioning are detected.

[0009] Indeed, during the web unwinding, the positioning of the web along the feed path, for example the longitudinal positioning, influences the correct nominal separation of each label from the web itself at the cutting station.

[0010] More specifically, the web must pass through the cutting station with its cut portions (ie, the connecting transverse edges between each pair of longitudinally adjacent labels) in the correct position to ensure nominal cutting of the web itself and subsequent nominal application of the labels to the containers.

[0011] For this purpose, a typical labeling module comprises a sensor system including an optical sensor and a control unit.

[0012] The optical sensor is configured to detect a reference element on each label in turn prior to cutting the web, such as an aesthetic pattern or theme or design printed on the label.

[0013] In order to achieve the above object, the optical sensor is configured to acquire an image of a detection area corresponding to a field of view of the optical sensor at a predetermined frequency.

[0014] The predetermined frequency is related to the production speed. For example, if five tags should pass through the field of view (ie, the detection area) per second, the acquisition frequency will be set to 5 Hz, i.e., five acquisitions per second.

[0015] The Applicant has observed that an optical sensor may "loose" a reference element in certain circumstances. More specifically, an element initially implemented as a reference in the sensor system and initially correctly located within a detection zone and field of view may be located outside such detection zone or field of view for a certain number of consecutive labels.

[0016] This can occur, for example, if the phase shift of the web is too large.

[0017] In this case, the labeling machine must be stopped and the sensor system manually recalibrated and reinitialized in order to re-implement the reference element in the sensor system (ie so that the reference element is again within the field of view and / or within the reference area).

[0018] This is also necessary at the beginning of a labelling process or when the label format changes, in which case a new reference element needs to be implemented manually.

[0019] Furthermore, once a reference element is selected and implemented, it may happen that the optical sensor erroneously detects a feature on the label that is similar to the reference element, even though the feature is not the reference element. Summary of the invention

[0020] It is therefore an object of the present invention to provide a label feeding system for a labelling machine which is designed to overcome at least one of the above-mentioned disadvantages in a simple and cost-effective manner.

[0021] This object is achieved by a label feeding system according to claim 1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Non-limiting embodiments of the present invention will be described below by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic top view of a labelling machine (with parts removed for clarity) having a label feeding system according to the invention for feeding a web of labelling material through the labelling machine; Figure 2 Under normal operating conditions, Figure 1 The system feeds the web and Figure 1 Schematic side view of some parts of the system (with parts removed for clarity); FIG. 3a to FIG. 3c are diagrams of three different operating conditions according to the recovery operation mode of the system. Figure 1 Schematic side view of a web and some parts of the system (with parts removed for clarity); 4a to 4c are diagrams showing three different operating conditions of the recovery operation mode of the system according to the second preferred embodiment of the present invention. Figure 1 Schematic side view of a web and some parts of the system (with parts removed for clarity); and Figures 5a to 5c are diagrams of three different operating conditions in the system verification operation mode. Figure 1 Schematic side view of the web and some parts of the system (parts are removed for clarity). DETAILED DESCRIPTION

[0023] refer to Figure 1 , reference numeral 1 denotes as a whole a labelling machine for labelling containers 2, such as bottles, vials, jars or the like, suitable for containing pourable products, preferably pourable foodstuffs.

[0024] The labelling machine 1 is configured to apply labels 3 obtained from a web 4 of labelling material to containers 2 .

[0025] According to this preferred and non-limiting embodiment, the labels 3 are adhesive labels, ie strips of labelling material are cut from the web 4 at predetermined lengths and then sprayed with glue before they are applied to the respective containers 2 .

[0026] The web 4 is provided in the form of a continuous strip which is initially wound on a reel 5 and from which, in use, is gradually unwound along a feed path P in a known manner.

[0027] like Figure 2 As shown schematically, the web 4 comprises a plurality of labels 3 connected longitudinally.

[0028] More specifically, the labels 3 are joined together at their respective transverse edges, at which edges the web 4 is cut to obtain separate labels 3 .

[0029] Each label 3 has a plurality of longitudinal portions, ie portions of labelling material arranged at specific and unique longitudinal coordinates relative to the longitudinal extension of the label along the feed path P.

[0030] Each longitudinal portion therefore has a longitudinal extension that is smaller than the total longitudinal length of the corresponding label 3 .

[0031] Each label 3 has an aesthetic feature AF arranged at a determined longitudinal portion, such as Figure 2 Shown schematically.

[0032] The aesthetic features AF define a reference element on each label 3 .

[0033] The aesthetic features AF may be defined by a pattern or aesthetic theme or design printed on the surface of each label 3 .

[0034] like Figure 1 As shown, the labeling machine 1 comprises: a conveying device, preferably a turntable 6, rotatable about a central axis X (preferably vertical) and configured to advance a plurality of containers 2 along an arcuate labeling path (preferably horizontal); a labelling module 7 (shown only schematically) arranged relative to the periphery of the carousel 6 and configured to prepare a plurality of labels 3 and feed them to the carousel 6 at the application station A for application thereof onto respective containers 2 .

[0035] The labeling module 7 comprises: - a fixed frame 8; - a support shaft 10 for supporting one reel 5 at a time in an expandable manner; a feed roller 11 rotatably fixed to the frame 8 , rotatably actuated to feed the web 4 along a feed path P extending inside and through the labelling module 7 , the feed roller 11 being conveniently arranged downstream of the support shaft 10 along the feed path P; a plurality of guide rollers 12 (only one is shown) operatively arranged downstream of the support shaft 10 and the feed roller 11 and configured to support the web 4 gradually unwound from the reel 5 and to guide the web 4 along the feed path P; a cutting unit 13 (known per se and not described in detail) arranged along the feed path P downstream of the guide roller 12 and configured to repeatedly cut the web 4 at a cutting station C in order to separate a series of labels 3 therefrom; and - a transfer roller 14, preferably a vacuum roller of known type, which is arranged downstream of the cutting unit 13, is mounted on the frame 8 in a rotatable manner about a central axis (preferably parallel to the axis X) and is configured to transfer the labels 3 to the application station A for applying them to the corresponding containers 2.

[0036] The feed roller 11 is supported by the frame 8. The feed roller 11 is configured to feed the web 4 by rotating itself and relative to the frame 8.

[0037] Since in this preferred non-limiting embodiment, the label 3 requires the use of glue, the labeling module 7 also includes at least one glue roller 50, which is arranged to be basically tangential to the conveying roller 13 and is configured to apply glue to at least the end of each individual label 3 before the label 3 is applied to the container 2.

[0038] The feed roller 11 is of known type, rotatable about a central axis W (preferably parallel to the axis X).

[0039] The feed roller 11 is part of a label feeding system 15 and is configured for feeding the web 4 (ie along a feed path P) through the labelling module 7 .

[0040] The system 15 further comprises: a sensor device comprising an optical sensor 17 having a field of view FV and configured to repeatedly check the field of view FV; a control unit 18 operatively connected to the optical sensor 17 and the feed roller 11 ; and A reference member 16 which is fixed relative to the feed path P and the field of view FV and is arranged within the field of view FV so as to be detectable by the optical sensor 17 .

[0041] The frame 8 supports the sensor device such that the field of view FV can be fixed relative to the frame 8 .

[0042] The reference member 16 comprises at least a portion of a physical body, such as a mechanical rod or bar, which is supported by the frame 8 such that the physical body can be fixed relative to the frame 8 .

[0043] exist Figure 1In the figure, for the sake of clarity, only a small part of the frame 8 is shown, namely the part of the frame 8 supporting the reference member 16.

[0044] The feed roller 11 is configured to feed the web 4 through the field of view FV.

[0045] The aesthetic feature AF may be detected by the optical sensor 17, in particular when it passes through the field of view FV.

[0046] Preferably, the optical sensor 17 is fixable to, in particular to, the frame 8 .

[0047] Preferably, the reference member 16 is fixable to, in particular to, the frame 8. Thus, the reference member 16 is fixed relative to the web 4 advancing along the path P.

[0048] Preferably, the reference member 16 comprises, in particular is defined by, a mechanical rod or bar mounted in a fixed position on the frame 8 and operatively interposed between the feed roller 11 and the cutting unit 13 , in particular between the feed roller 11 and the guide roller 12 .

[0049] In detail, the optical sensor 17 is arranged on the opposite side of the reference member 16 relative to the feed path P and therefore on the opposite side of the web 4 advancing along it, that is, on the other side of the feed path P (and the web 4 fed along it) relative to the reference member 16.

[0050] The above-mentioned check is therefore performed by the optical sensor 17 on the labels 3 which are still connected together to form the web 4 .

[0051] Preferably, the optical sensor 17 comprises, in particular is defined by, a camera.

[0052] The sensor device is configured to operate in production mode ( Figure 2 ), according to which, for each label 3 , the optical sensor 17 sequentially acquires an image I of the field of view FV at said determined longitudinal portion in order to detect the linear distance between the corresponding aesthetic feature AF and the reference member 16 .

[0053] Suitably, the optical sensor 17 is configured to acquire each image I for each tag 3 in turn when the determined longitudinal portion of each tag 3 passes through the field of view FV.

[0054] More precisely, the sensor device is configured so that the longitudinal position of each respective tag 3 relative to the field of view FV is the same for all images I acquired during the production mode.

[0055] In other words, during production mode, all images I are acquired when the same longitudinal portion of each label passes through the field of view FV.

[0056] For example, refer to Figure 2 The optical sensor 17 acquires each image I when the terminal longitudinal portion of each label 3 , at which terminal longitudinal portion the aesthetic feature AF is arranged according to the example shown, passes through the field of view FV.

[0057] Preferably, the detected linear distance is the distance along the longitudinal direction (ie along the path P).

[0058] The linear distance may also be a lateral distance relative to the path P.

[0059] Based on the detected linear distance between the aesthetic feature AF and the reference member 16 , the control unit 18 controls the rotation speed of the feed roller 11 , thereby adjusting the phase of the web 4 .

[0060] According to one aspect of the invention, the sensor device is further configured to operate in a recovery mode, according to which the optical sensor 17 acquires a plurality of images I1, I2, I3 of the field of view FV for searching for the aesthetic feature AF, wherein each image I1, I2, I3 of the plurality of images comprises at least one longitudinal portion that is different from other longitudinal portions comprised in other images I1, I2, I3 of the plurality of images, so that all different longitudinal portions are cumulatively checked during the recovery mode by a single tag 3 or by a plurality of tags 3a, 3b, 3c.

[0061] In more detail, according to a first preferred embodiment schematically shown in FIGS. 4a , 4b , 4c , the sensor device is configured such that during recovery mode, the optical sensor 17 sequentially acquires a plurality of images including at least a first image I1 and a second image I2 of a single label 3 to be inspected.

[0062] In the example shown, the optical sensor 17 captures a first image I1 , a second image I2 and a third image I3 of a single label 3 .

[0063] According to this first preferred embodiment, in each image I1, I2, I3 of the plurality of images, the label 3 has a corresponding longitudinal position relative to the field of view FV, which is different from the longitudinal position of the same label 3 in all other images I1, I2, I3 of the plurality of images.

[0064] For example, in image I1 (FIG. 4a), label 3 has a longitudinal position, i.e., it is in a longitudinal position relative to the field of view FV, which is different from the longitudinal position of the same label 3 in image I2 (FIG. 4b) and image I3 (FIG. 4c), and so on.

[0065] In practice, the sensor device is configured so that the optical sensor 17 acquires images I1 , I2 , I3 of all longitudinal portions of a single label 3 in order to search for aesthetic features AF in order to define a restoration pattern.

[0066] If the aesthetic feature AF is not found in this particular tag 3 , the recovery mode is performed on subsequent tags 3 .

[0067] Such a recovery mode is advantageous, for example, when the optical sensor 17 for some reason "loses" the aesthetic feature AF, ie its reference element based on which the control unit 18 monitors the development of the web 4 along the path P.

[0068] Advantageously, during the above-mentioned recovery mode, the control unit 18 is configured to reduce the rotation speed of the feed roller 11, thereby causing a deceleration of the web 4 along the feed path P and thus of each label 3 passing through the field of view FV.

[0069] In this way, the optical sensor 17 is able to perform the acquisition of different images I1, I2, I3 for all longitudinal portions of the label 3 without excessively increasing the acquisition frequency. This ensures the effectiveness and accuracy of the acquisition, and therefore the effectiveness and accuracy of the aesthetic feature AF search. In addition, it is ensured that the upper limit of the acquisition frequency of the optical sensor 17 is not reached or exceeded.

[0070] The optical sensor 17 is configured to acquire images I of the field of view FV at a first acquisition frequency during a production mode of the sensor device.

[0071] “Acquisition frequency” refers to the acquisition time frequency, for example, in Hz.

[0072] The optical sensor 17 is configured to acquire images I1 , I2 , I3 of the field of view FV at a second acquisition frequency during the recovery mode of the sensor device, wherein the second acquisition frequency is different from the first acquisition frequency.

[0073] Conveniently, the second acquisition frequency is higher than the first acquisition frequency.

[0074] In detail, the control unit 18 is configured to command an increase in the acquisition frequency of the optical sensor 17 during the recovery mode relative to the production mode.

[0075] In this way, the rotation speed of the feed roller 11 does not have to be reduced excessively, so that the labeling process is not slowed down too much during the recovery mode.

[0076] Thanks to the label feeding system 15 according to the above configuration, in case the optical sensor 17 loses the aesthetic feature AF, it is no longer necessary to stop the labelling machine 1 and manually recalibrate and reinitialise the sensor device.

[0077] In fact, re-implementing the aesthetic feature AF in the sensor device can be performed automatically and on the fly (ie during production, without stopping the labeling process).

[0078] The above configuration is also particularly advantageous when starting a labeling process or when label specifications change, in which case a new reference element needs to be implemented.

[0079] Furthermore, due to the above-described configuration, since the search for the aesthetic feature AF can be performed by a single tag 3 , the total number of discarded tags 3 is reduced.

[0080] like Figure 2 As schematically shown in FIGS. 4 a to 4 c , the optical sensor 17 is configured to analyze, for each image I, I1, I2, I3 acquired during production mode and recovery mode, a pre-set reference region RR of the field of view FV in order to detect the aesthetic feature AF. In this way, the amount of calculation is reduced, since the reference region corresponds to a smaller area relative to the field of view FV. The reference region RR is preferably set in the machine by an operator.

[0081] Preferably, the field of view FV has a longitudinal extension, relative to and along the feed path P, which is a portion of the longitudinal length of each label 3 .

[0082] Conveniently, the minimum number of images I1 , I2 , I3 to be acquired during the recovery mode for searching for the aesthetic feature AF is at least equal to the ratio between the longitudinal length of the label 3 and the longitudinal extension of the field of view FV.

[0083] Therefore, the sensor device is configured so that the number of images I1 , I2 , I3 acquired during the recovery mode for searching for the aesthetic feature AF is greater than or equal to the ratio between the longitudinal length of the tag 3 and the longitudinal extension of the field of view FV.

[0084] More precisely, the minimum number of images I1 , I2 , I3 to be acquired during the restoration mode for searching for the aesthetic feature AF is at least equal to the first integer following the value of the above ratio.

[0085] For example, in the case shown in FIGS. 4 a to 4 c , where the longitudinal extension of the field of view FV is 1 / 3 of the longitudinal length of each label 3 , the minimum number of images to be acquired in order to check all longitudinal portions is three.

[0086] In this way, it is ensured that all of the aforementioned longitudinal sections are inspected by the optical sensor 17 .

[0087] 3a, 3b and 3c schematically show a second preferred embodiment of a sensor device according to the invention.

[0088] Since the sensor device according to the second embodiment is similar to the sensor device according to the first embodiment, only the differences between the two will be described below.

[0089] Specifically, the sensor device according to the second embodiment is configured such that, during the recovery mode, for a tag group 3 comprising at least a first tag 3a and a second tag 3b, the optical sensor is configured to acquire at least one single image I1, I2, I3 for each tag 3a, 3b, 3c of the tag group 3.

[0090] In the example shown, the tag group 3 includes a first tag 3a, a second tag 3b, and a third tag 3c. Therefore, the optical sensor 17 is configured to acquire a first image I1, a second image I2, and a third image I3. More specifically, the optical sensor 17 acquires a single first image I1 of the first tag 3a, a single second image I2 of the second tag 3b, and a single third image I3 of the third tag 3c.

[0091] According to this second preferred embodiment of the sensor device of the present invention, the sensor device is configured so that in each acquired image I1, I2, I3, the longitudinal position of the corresponding label 3a, 3b, 3c of the label group 3 relative to the field of view FV is different from the longitudinal positions of other labels 3a, 3b, 3c of the label group 3 in the corresponding images I1, I2, I3.

[0092] For example, the optical sensor 17 acquires a first image I1 at a first longitudinal portion of a first label 3a (FIG. 3a); then the optical sensor 17 acquires a second image I2 at a second longitudinal portion of a second label 3b (FIG. 3b); and then the optical sensor 17 acquires a third image I3 at a third longitudinal portion of a third label 3c (FIG. 3c).

[0093] Therefore, in the first image I1 (Figure 3a), the first label 3a has a longitudinal position, that is, it is in a longitudinal position relative to the field of view FV, which is different from the longitudinal position of the second label 3b in the second image I2 (Figure 3b), and also different from the longitudinal position of the third label 3c in the third image I3 (Figure 3c), and so on.

[0094] In practice, the sensor device is configured so that the optical sensor 17 acquires images I1 , I2 , I3 of all longitudinal portions of a tag 3 through a plurality of tags 3a , 3b , 3c in order to search for aesthetic features AF defining a restoration pattern.

[0095] Thanks to the above described configuration, the search and re-realization of the aesthetic feature AF can be performed without stopping the labelling machine 1 and the labelling process and without slowing down the labelling process.

[0096] In other words, the advancement speed of the web 4 along the feed path P can be kept constant.

[0097] This is particularly advantageous with regard to the inertial conditions of the system, since the feed roller 11 does not have to be slowed down and then accelerated again to re-establish the production speed.

[0098] Furthermore, complicated control of the speed of the feed roller 11 can be avoided.

[0099] Therefore, the aforementioned second acquisition frequency is suitably lower than the first acquisition frequency, so that all longitudinal sections can be completely inspected by a plurality of tags 3 .

[0100] Compared to the first embodiment described above, more labels are needed to re-implement the aesthetic features AF in the sensor device, thereby increasing the number of discarded labels 3. However, the advantages of the first embodiment in terms of inertial conditions and speed of the labeling process are obvious.

[0101] With reference to Figs. 5a, 5b and 5c, another mode of operation of the sensor device according to the invention will be described, wherein the same reference numerals are used as much as possible for corresponding elements.

[0102] The optical sensor 17 is configured to acquire said images I, I1 , I2 , I3 with a first level of accuracy.

[0103] In one embodiment, the accuracy level is defined by the contrast level of the image in the field of view FV.

[0104] Specifically, the sensor device according to the present invention is configured to operate in a verification mode, according to which the optical sensor 17 sequentially acquires multiple images I1, I2, I3 for multiple labels 3 (for example, a single label 3 as shown in Figures 5a to 5c) at a second accuracy level lower than the first accuracy level to detect whether there is an additional aesthetic feature AF' on each of the multiple labels 3 that may be confused with the aesthetic feature AF.

[0105] More specifically, the sensor device is configured such that during the verification mode, the optical sensor 17 acquires, for each tag 3 of the plurality of tags 3 in turn and at the second level of accuracy, a plurality of images comprising at least a first image I1 and a second image I2 .

[0106] In the example shown, the optical sensor 17 captures a first image I1 , a second image I2 and a third image I3 of a single label 3 .

[0107] According to the present invention, the sensor device is configured so that in each image I1, I2, I3 of the multiple images, the tag 3 has a respective longitudinal position relative to the field of view FV, which is different from the longitudinal position of the same tag 3 in all other images I1, I2, I3 of the multiple images.

[0108] In fact, during the verification mode, the optical device 17 operates according to the first embodiment described above, except that the accuracy level is changed from the first accuracy level to the second accuracy level.

[0109] Thus, in image I1 (FIG. 5a), label 3 has a longitudinal position, i.e. it is in a longitudinal position relative to the field of view FV, which is different from the longitudinal position of the same label 3 in image I2 (FIG. 5b) and image I3 (FIG. 5c), and so on.

[0110] In practice, the sensor device is configured so that the optical sensor 17 acquires images I1 , I2 , I3 of all longitudinal portions of the label 3 in order to search for further aesthetic features AF′ defining the authentication pattern.

[0111] The verification mode is successful if no further aesthetic feature AF' as defined above is detected in the label 3. Indeed, if no further aesthetic feature AF' as defined above is detected at a contrast level lower than the contrast level used during the production mode, it is certain that, at the nominal contrast level, the optical sensor 17 will not confuse the aesthetic feature AF with other aesthetic features printed on the label 3.

[0112] If the further aesthetic feature AF' as defined above is indeed detected in the label 3, the verification mode is unsuccessful and another aesthetic feature different from the aesthetic feature AF must be implemented as reference element to avoid that the optical sensor 17 could confuse the aesthetic feature AF with the further aesthetic feature AF' during the production mode.

[0113] The above configuration can avoid that the optical sensor 17 erroneously detects features on the label similar to the reference element during the production mode. In this way, an erroneous calculation of the linear distance between the reference element and the reference member 16 and thus an erroneous cutting of the web 4 is avoided.

[0114] From the above description, the advantages of the label feeding system 15 according to the present invention will become apparent.

[0115] In particular, due to the recovery mode of the sensor device, the search and re-realization of the aesthetic feature AF can be performed without stopping the labeling machine 1 and the labeling process. More specifically, if the optical sensor 17 loses the aesthetic feature AF, it is no longer necessary to stop the labeling machine 1 and manually recalibrate and reinitialize the sensor device.

[0116] In fact, re-implementing the aesthetic feature AF in the sensor device can be performed automatically and on the fly (ie during production and without stopping the labeling process).

[0117] The above configuration is also particularly advantageous when starting a labeling process or when label specifications change, in which case a new reference element needs to be implemented.

[0118] Furthermore, due to the verification mode of the sensor device, it is avoided that the optical sensor 17 during the production mode erroneously detects features on the label that are similar to reference elements.

[0119] Obviously, changes may be made to the label feeding system 15 described herein without, however, departing from the scope of protection defined by the appended claims.

Claims

1. A label feeding system (15) for a labelling machine (1) configured to label containers (2) suitable for containing pourable products, the label feeding system (15) comprising: - a sensor device comprising an optical sensor (17) having a field of view (FV) and configured to repeatedly examine said field of view (FV); - a frame (8) supporting the sensor device such that the field of view (FV) can be fixed relative to the frame (8); a feed roller (11) for longitudinally feeding a web (4) of labelling material along a feed path (P) and across the field of view (FV), the web (4) comprising a plurality of longitudinally connected labels (3), each label (3) having a plurality of longitudinal portions and an aesthetic feature (AF) arranged at a determined longitudinal portion, the aesthetic feature (AF) being detectable by the optical sensor (17), the feed roller (11) being supported by the frame (8) and being configured to feed the web (4) by rotating about itself and relative to the frame (8); and - a reference member (16) fixed relative to said field of view (FV) and arranged within said field of view (FV) so as to be detected by said optical sensor (17); The sensor device is configured to operate in a production mode according to which, for each label (3), the optical sensor (17) sequentially acquires an image (I) of the field of view (FV) at the determined longitudinal portion in order to detect the linear distance between the corresponding aesthetic feature (AF) and the reference member (16); The sensor device is further configured to operate in a recovery mode, according to which the optical sensor (17) acquires a plurality of images (I1, I2, I3) of the field of view (FV) for searching for the aesthetic feature (AF), wherein each image (I1; I2; I3) of the plurality of images comprises at least one longitudinal portion that is different from the other images (I2, I3; I1, I3; I1, I2) so that all different longitudinal sections are cumulatively checked during said recovery mode by a single tag (3) or by a plurality of tags (3a, 3b, 3c).

2. A label feeding system as claimed in claim 1, wherein the sensor device is configured so that during the production mode, the longitudinal position of each corresponding label (3) relative to the field of view (FV) is the same for all the images (I) acquired.

3. The label feeding system of claim 2, wherein the sensor device is configured so that during the recovery mode, the optical sensor (17) sequentially acquires a plurality of images (I1, I2, I3) for a single label (3), the plurality of images (I1, I2, I3) comprising at least a first image (I1) and a second image (I2), And wherein the sensor device is configured so that in each image (I1; I2; I3) of the plurality of images, the tag (3) has a respective longitudinal position relative to the field of view (FV), which longitudinal position is different from the longitudinal position of the same tag (3) in all other images (I2, I3; I1, I3; I1, I2) of the plurality of images.

4. A label feeding system according to claim 3, wherein said sensor device comprises a control unit (18) operatively connected to said optical sensor (17) and said feed roller (11); And wherein the control unit (18) is configured to reduce the rotation speed of the feed roller (11) during the recovery mode, thereby causing the web (4) to decelerate along the feed path (P) and through the field of view (FV).

5. A label feeding system according to claim 2, wherein the sensor device is configured such that during the recovery mode, for a label group (3a, 3b, 3c) comprising at least a first label (3a) and a second label (3b), the optical sensor (17) is configured to acquire at least one single said image (I1, I2, I3) for each label (3a, 3b, 3c) of the label group; and wherein the sensor device is configured so that in each acquired image (I1, I2, I3), a corresponding tag (3a; 3b; 3c) of the tag group has a longitudinal position relative to the field of view (FV) that is identical to other tags (3b, 3c; 3a, 3c; 3a, 3b) have different longitudinal positions.

6. A label feeding system as claimed in any one of the preceding claims, wherein the optical sensor (17) is configured to analyse a predetermined reference region (RR) of the field of view (FV) for each image (I; I1, I2, I3) acquired during the production mode and during the recovery mode to detect the aesthetic feature (FV).

7. A label feeding system according to any one of the preceding claims, wherein the field of view (FV) has a longitudinal extension relative to the feed path (P), the longitudinal extension being a portion of the longitudinal length of each label (3); And wherein the sensor device is configured so that the number of images (I1, I2, I3) acquired during the recovery mode for searching for the aesthetic feature (AF) is greater than or equal to the ratio between the longitudinal length of the tag (3) and the longitudinal extension of the field of view (FV).

8. A label feeding system as claimed in claim 7, wherein the number of images acquired during the recovery mode for searching for the aesthetic feature (AF) is greater than or equal to the first integer after the numerical value of the ratio between the longitudinal length of the label (3) and the longitudinal extension of the field of view (FV).

9. A label feeding system as claimed in any one of the preceding claims, wherein the reference member (16) comprises at least a portion of a physical body, such as a mechanical rod or bar, which is supported by the frame (8) so that the physical body can be fixed relative to the frame (8).

10. A label feeding system according to any one of the preceding claims, wherein said optical sensor (17) is configured to acquire said image (I) of said field of view (FV) at a first acquisition frequency during said production mode; and wherein the optical sensor (17) is configured to acquire the image (I1, I2, I3) of the field of view (FV) at a second acquisition frequency during the recovery mode, The second acquisition frequency is different from the first acquisition frequency.

11. The label feeding system as claimed in claims 3 and 10, wherein the second acquisition frequency is higher than the first acquisition frequency.

12. The label feeding system as claimed in claims 5 and 10, wherein the second acquisition frequency is lower than the first acquisition frequency.

13. A label feeding system according to any one of the preceding claims, wherein said optical sensor (17) is configured to acquire said image (I; I1, I2, I3) at a first level of accuracy; And wherein the sensor device is configured to operate in a verification mode, according to which the optical sensor (17) sequentially acquires a plurality of images (I1, I2, I3) for a plurality of labels (3) or for a single label (3) at a second accuracy level lower than the first accuracy level to detect whether there is an additional aesthetic feature (AF') on each label (3) of the plurality of labels (3) that may be confused with the aesthetic feature (AF).

14. A label feeding system according to claim 13, wherein the sensor device is configured so that during the verification mode, the optical sensor (17) sequentially acquires a plurality of images (I1, I2, I3) for each label (3) and at the second level of accuracy, the plurality of images (I1, I2, I3) comprising at least a first image (I1) and a second image (I2), And wherein the sensor device is configured so that in each image (I1, I2, I3) of the plurality of images, the tag (3) has a respective longitudinal position relative to the field of view, which longitudinal position is different from the longitudinal position of the same tag (3) in all other images (I2, I3; I1, I3; I1, I2) of the plurality of images.

15. A label feeding system as claimed in claim 13 or 14, wherein the accuracy level is defined by the contrast level of the image in the field of view (FV).

16. A labelling machine (1) for labelling containers (2) suitable for containing pourable products with labels (3), the labels being obtained from a web (4) of labelling material, the web (4) comprising a plurality of longitudinally connected labels (3), each label (3) having a plurality of longitudinal portions and aesthetic features (AF) arranged at determined longitudinal portions, the labelling machine (1) comprising a labelling module (7) and a label feeding system (15) as claimed in any one of the preceding claims for feeding the web (4) through the labelling module (7), The labeling module (7) comprises: - a fixed frame (8); - a plurality of guide rollers (12) arranged on the fixed frame (8) and configured to support the web (4) and guide it along the feed path (P); a cutting unit (13) for repeatedly cutting the web (4) at a cutting station (C) in order to separate a series of labels (3) from the web (4) itself; and - a label transfer device (14) configured to receive, hold and advance each label (3) and to feed each label (3) towards said container (2) for application thereto.

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