Abstract:
To label products on a conveyor, a target area for a given product conveyed on the conveyor is determined relative to a frame of reference. One of a plurality of labellers fixed at different transverse positions over the conveyor, which one labeller is at a transverse position which is within the transverse extent of the target area is then activated in order to label the product. Each labeller may have a turret with a number of flexible bellows with an interior air diffuser. The air diffuser has a central opening facing the tamping end of the bellows and at least one side opening. This arrangement can enhance the responsiveness of the bellows. Each labeller may also have a de-mountable label cassette with a drive pinion which meshes with a two-sided timing belt. The two-sided timing belt is driven by a stepper motor in synchronism with the turret. The label cassette may have a driven pin wheel for moving the pin holed release tape of a label web. A ratchet tooth fixed in with respect to a pin of the pin wheel is engaged by a pawl to set a limit for driving the label web in a label web retracting direction in order to set a start position for a label on the web.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a method and apparatus for labelling products.  
           [0002]    Products to be sold are commonly labelled. In this regard, automatic labelling apparatus may be employed where the products are smaller and processed in large volumes. One approach in this regard is to wipe a label onto each product as its passes a labelling head. This approach, however, is only well suited for labelling products of uniform dimensions. Where products have irregular dimensions, such that the distance between a given product and the labelling head will vary, tamping labellers are typically used. U.S. Pat. No. 5,829,351 to Anderson discloses such a labeller. In Anderson, a turret carries a number of flexible pneumatic bellows about its periphery. The turret has a vacuum plenum and a positive pressure plenum. The turret rotates each bellows, consecutively, to a labelling station. A bellows normally communicates with the vacuum plenum which keeps it in a retracted position; also, due to end perforations in the bellows, the negative pressure holds a label at the end of the bellows. However, when the bellows reaches the labelling station, it is coupled to the positive pressure plenum which causes a one-way valve to block the perforations and causes the bellows to rapidly extend until it tamps a product below. The force of the tamping forms an adhesive bond between the pressure sensitive adhesive of the label and the product. Labels are fed to each bellows from a label cassette with a label web comprising serially arranged labels on a release tape. The release tape is split along a weakened centreline to release the labels.  
           [0003]    A problem arises if products are irregularly arranged such that they do not all pass directly below the labelling station. A further difficulty faced by a tamping apparatus employing a flexible bellows is in the accurate control of tamping with the bellows. Yet another difficulty is in the synchronisation of the label web with the bellows and in the ease of reloading a label cassette. This invention seeks to address at least some of these problems.  
         SUMMARY OF INVENTION  
         [0004]    In one aspect, a target area for a given product conveyed on a conveyor is determined relative to a frame of reference. One of a plurality of labellers fixed at different transverse positions over the conveyor, which one labeller is at a transverse position which is within the transverse extent of the target area is then activated in order to label the product. In another aspect, a labeller has a flexible bellows with an interior air diffuser. The air diffuser has a central opening facing the tamping end of the bellows and at least one side opening. This arrangement can enhance the responsiveness of the bellows. In a further aspect, a labeller has a two-sided timing belt driven by a stepper motor with a de-mountable label cassette which, when mounted, has a drive pinion meshing with the two-sided timing belt. In another aspect, a labeller has a label cassette with a driven pin wheel for moving a pin holed release tape of a label web. A ratchet tooth having a fixed relation to a pin of the pin wheel engages a pawl to set a limit for driving the label web in a label web retracting direction in order to set a start position for a label on the web. It is useful to set the label cassette at this start position when the cassette is first mounted and then occasionally thereafter in order to reduce the likelihood of label mis-feeds.  
           [0005]    Accordingly, the present invention provides labelling apparatus for use with a conveyor for conveying products in a downstream direction, comprising: a vision system for imaging products on said conveyor; a plurality of labellers downstream of said vision system, each labeller for being fixed above said conveyor at a different transverse position over said conveyor; a processor for, responsive to an input from said vision system, selecting a labeller to label a given product and sending an activation signal to one said labeller.  
           [0006]    According to another aspect of the invention, there is provided a method of labelling products, comprising conveying products in a downstream direction, determining a target area for a given product on the conveyor relative to a frame of reference, and activating a one of a plurality of labellers positioned above the conveyor at fixed transverse positions which one labeller is within a transverse extent of the target area. A computer readable medium is also provided to effect this method.  
           [0007]    According to a further aspect of the present invention, there is provided a product labelling apparatus comprising: at least one flexible bellows having a retracted position and an extended tamping position; an air diffuser associated with each bellows, each air diffuser extending interiorly of an associated bellows from a base of said associated bellows toward a tamping end of said associated bellows, said each air diffuser having a central opening facing said tamping end of said associated bellows and at least one side opening facing a side of said associated bellows.  
           [0008]    According to another aspect of the invention, there is provided a labelling apparatus comprising: an indexing turret carrying a plurality of tamping labellers; a stepper motor for stepping in synchronism with step-wise movement of said turret, said stepper motor for driving a two-sided timing belt; a releasable mount for a label web cassette; said label web cassette having a drive pinion, said drive pinion for meshingly engaging with said two-sided timing belt when said label web cassette is mounted to said releasable mount.  
           [0009]    According to a further aspect of the invention, there is provided a labelling apparatus comprising: an indexing turret carrying a plurality of tamping labellers; a label web cassette normally driven in synchronism with said indexing turret; wherein a label web of said cassette has a pin hole between each label and wherein said label web cassette has a driven pin wheel engaging said pin holes; and a ratchet tooth fixed in relation to a pin of said pin wheel and a pawl setting a limit for driving said label web cassette in a label web retracting direction whereby said label web may be retracted so that a label is at a pre-determined start position.  
           [0010]    Other aspects and features of the invention will become apparent be reference to the following description in conjunction with the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    In the figures which set out example embodiments of the invention,  
         [0012]    [0012]FIG. 1 is a top plan schematic view of a labelling apparatus made in accordance with this invention,  
         [0013]    [0013]FIGS. 2A and 2B are front and side views, respectively, of a labeller which may be used in the apparatus of FIG. 1,  
         [0014]    [0014]FIG. 3 is a side view detail of a portion of the labeller of FIGS. 2A, 2B,  
         [0015]    [0015]FIG. 4 is a perspective view of a turret of the labeller of FIGS. 2A, 2B,  
         [0016]    [0016]FIG. 5 is a perspective view, and FIG. 5A a side view, of a portion of the turret of FIG. 4,  
         [0017]    [0017]FIGS. 6A and 6B are front and side views, respectively, of another portion of the turret of FIG. 4,  
         [0018]    [0018]FIG. 7 is an exploded view, and FIG. 7A a side view, of a further portion of the turret of FIG. 4,  
         [0019]    [0019]FIG. 8 is a plan view of a label web used with the apparatus of FIG. 1, and  
         [0020]    [0020]FIG. 9 is a flow diagram for operation of a processor of the apparatus of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0021]    Turning to FIG. 1, a labelling apparatus  10  comprises labellers  12   a  to  12   h  (referred to individually as labellers  12 ) mounted by mounts  14  at a fixed position above a conveyor  16 . The labellers  12  are arranged as an upstream bank  18   u  of labellers ( 12   a  to  12   d ) and a downstream bank  18   d  of labellers ( 12   e  to  12   h ). Each bank  18   u ,  18   d  of labellers extends transversely of the conveyor  16 . The labellers in a bank are equally spaced and the labellers of the downstream bank  18   d  are offset from those of the upstream bank  18   u  so that each labeller has a different transverse position over the conveyor. Further, the labellers  12  extend substantially across the width of the conveyor so as to provide eight distinct transverse positions across the conveyor. The labellers  12  are operatively connected to processor  22  on paths  20 .  
         [0022]    The labellers  12  are downstream of a camera  24 ; the camera is arranged to image an area of the conveyor and output this image to the processor  22 . In this regard, products  26  may be carried in trays  28  and the camera may image an area which captures one such tray. For example, as illustrated, the products may be vine ripened tomatoes which remain attached to vines  30  such that the products are irregularly spaced. A conveyor position indicator  32  (which, for example, may be a rotary encoder, a sensor which senses marks on the conveyor, or, where the conveyor moves at a known constant speed, simply a timer) also outputs to the processor.  
         [0023]    A labeller  12 , in its various aspects, is illustrated in FIGS.  2  to  7 . Referencing FIGS. 2A and 2B, the labeller  12  has a turret  40  rotatably mounted to a base  38 . A drive belt  42  connects the turret  40  to a stepper motor  44 . A label cassette  50  is releasably mounted to base  38  by way of a loading peg  48  at the rear of the cassette which slides into a notch  52  on the base and allows the cassette to be pivoted forwardly into a releasable latch (not shown) at the front of the base.  
         [0024]    The label cassette has a cassette magazine  54  to which is wound a label web  56  of the type illustrated in FIG. 8. Thus, the web comprises a release tape  58  carrying a plurality of labels  60  backed with a pressure sensitive adhesive. A pin hole  62  is provided in the release tape between each pair of labels. The label web extends from the cassette magazine  54  to a pin wheel  66  of the label cassette  50 , then through a C-channel member  68  to a label pickup station  70 , with the release tape  58  returning to wind around a pin wheel  72 . Pin wheel  72  is concentrically mounted to drive pinion  74 . With the cassette  50  mounted to base  38 , the drive pinion  74  is meshed with a two-sided timing belt  78  on the base. The two-sided timing belt is driven by a stepper motor  84 . A communication path  20  from the processor  22  (FIG. 1) terminates at stepper motors  44  and  84 .  
         [0025]    As seen in FIG. 3, pin wheel  72  has a circumferential portion  82  which carries a ratchet tooth  86  for each pin  88  on the wheel  72 . Each ratchet tooth has an operative edge  90  aligned with a pin  88 . A spring loaded pawl  92  is urged against circumferential portion  82 .  
         [0026]    The turret  40  is detailed in FIGS.  4  to  7 . Referencing FIGS. 4, 5, and  5 A, turret  40  has a stationary core  110  fixed to base  38 . The core has a port  112  for connection to a vacuum source (not shown) and a port  114  for connection to a source of positive pressure (not shown). Port  112  connects to an airway having a substantially circumference channel  118  opening to the periphery of the core. Port  114  connects to an airway having a slot  120  opening to the periphery of the core between the ends of the channel  118  so as to leave lands  124  between the ends of the channel  118  and slot  120 . The core  110  is oriented so that slot  120  is positioned over a label applying station  128 .  
         [0027]    Referencing FIGS. 6A and 6B along with FIG. 4, turret  40  has a sleeve  130  closely fit to the core  110 . Both the core and sleeve are fabricated of an ultra-high molecular weight (UHMW) polymer, or other material having a low co-efficient of friction. Thus, closely fitting sleeve  130  can rotate on core  110  absent other bearings between the two members. Sleeve  130  has a flange  132  which receives drive belt  42  (FIG. 1). The sleeve also has a number of peripheral through holes  134  comprising cylindrical openings  136  extending from its outer surface which terminate in slots  138  extending through its inner surface. A ratchet tooth  142  is associated with each through opening  134  having an operative edge  144  proximate a leading edge of its associated opening  134 . A spring loaded pawl (not shown) mounted to base  38  (FIG. 2A) is urged against the ratchet tooth bearing periphery of sleeve  130 .  
         [0028]    Referring to FIGS. 7 and 7A with FIG. 4, an air diffuser  140  has a base  142  which is press fit into each cylindrical opening  136  (FIG. 6A) of sleeve  130 . The air diffuser also has a snout  144  with a central opening  146  and side openings  148 . The air diffuser base  142  has a central opening  150  in fluid communication with the openings  146 ,  148  of the snout  144 . The air diffuser has a lip  152  for mounting a bellows  160 . Each bellows  160  is fabricated of a flexible material, such as rubber or silicone, which can be stretched over a lip  152  of an air diffuser  140 . The tamping end  162  of the bellows is perforated with pin holes  164 . A one-way valve at the tamping end comprises a flexible disk  166  internally mounted in the bellows  160  at a small stand off from the tamping end  162  by a short post  168 . It will be noted from FIG. 7A that with a bellows  160  mounted to an air diffuser  140 , the disk  166  seats on the central opening  146  of the air diffuser when the bellows is in its fully retracted position.  
         [0029]    To prepare labelling apparatus  10  for operation, label cassettes  50  are first readied. To ready a cassette, a full magazine  54  is loaded on the cassette then the end of the label web  56  is drawn from the magazine around pin wheel  66 , through channel  68  and back to pin wheel  72  such that the pins of each pin wheel are embedded in the pin holes of the web. So as not to waste labels during set-up, the web may have a leader portion free of labels. A readied cassette  50  may be mounted to the base  38  of a labeller  12  by inserting peg  48  of the cassette into notch  52  of the base then tilting the cassette  50  forwardly until the cassette latches to a latch carried by the base  38 . While the cassette is being tilted forwardly, pinion  74  contacts double-sided timing belt  78  ever more forcefully, deforming the belt thereby ensuring that teeth of the pinion  74  will mesh with the belt. In the latched position of the cassette seen in FIG. 2B, belt  78  is perpetually deformed by the pinion. This deformation results in the timing belt wrapping around a portion of the periphery of the pinion  74  so that a greater number of teeth of the pinion engage with the timing belt.  
         [0030]    Next each labeller may be moved to a start position (S 210 ). To do so, processor  22  signals stepper motor  84  to rotate in a direction which will wind the label web  56  back on to the magazine  54 . With specific reference to FIG. 3, stepper motor  84  then rotates in a counter clockwise direction so that pinion  74 , with its concentrically mounted pin wheel  72 , rotates clockwise. This continues until pawl  92 , which rides along periphery  82  of the pin wheel  72 , engages an engaging face  90  of a ratchet tooth  86 , whereupon stepper motor  84  stalls out as it can rotate counter clockwise no further. It will be recalled that there is a pin  88  for each ratchet tooth  86  and that the engaging face  90  of each tooth  86  has the same relative position with respect to an associated pin  88 . It will also be recalled that there is one pin hole  62  between each pair of labels on the label web. In consequence, with an appropriate choice of the distance between pin wheel  72  and the label pick-up station  70 , a label  60  will be at a pre-selected location with respect to the labelling station when the stepper motor  84  stalls. This is the start position for the labelling cassette  12 . The start position of the label cassette will normally be such that a label is present just upstream of the label pick-up station  70 . Similarly, processor  22  may signal stepper motor  44  to rotate backwards (clockwise) until a pawl (not shown) engages the engaging face  144  of a ratchet tooth  142  on sleeve  130  of turret  40  whereupon stepper motor  44  will stall (S 212 ). This defines the start position for turret  40 . The start position for turret  40  will normally be such that a bellows  160  is at the label pick-up station  70 .  
         [0031]    If not done previously, the positive and negative pressure ports  114 ,  112 , respectively, of each labeller are then coupled to appropriate air pressure sources. This couples a negative pressure to each bellows  160  of the turret  40  of a labeller thereby drawing each bellows to a collapsed position shown in FIG. 4. A bellows remains in this collapsed state except when at the label applying station  128 . This is due to the configuration of the core  110  with its substantially circumferential channel  118  coupled to the vacuum source. The lands  124  of the core substantially isolate the negative pressure in the channel  118  from the positive pressure in the slot  120  (which slot is aligned with the label applying station).  
         [0032]    With a vacuum source coupled to a bellows  160 , the one-way disk valve  166  is open such that there is a low pressure beyond the tamping head  162  of the bellows. Thus, a bellows  160  at the label pick-up station is ready to pick-up a label. The processor then sends an activation signal to stepper motor  84  causing it to advance the label web  56  by a fixed increment. This moves a label on the web from just upstream of the label pick-up station  70  to station  70  whereat the release tape turns back on itself around the end of channel  68  causing the label to peel off. Since a bellows  160  is already at this station, the released label  60  is sucked onto tamping head  162  presenting its pressure sensitive adhesive side outwardly. The processor then activates stepper motor  44  to rotate the turret  40  by a fixed increment in advancement direction A (FIG. 2B) so as to advance the next bellows  160  to the label pick-up station  70  and then again activates stepper motor  84  to advance the next label to the label pick-up station. This is repeated until all bellows extending in the advancement direction A between the label pick-up station and the label applying station  128  are loaded with a label (as shown in FIG. 2B, this would be four bellows) (S 214 ).  
         [0033]    Conveyor  16  may be started in downstream direction D. The conveyor may hold a number of trays  28 , each loaded with products  26 . When a tray reaches an imaging station, camera  24  images the tray and its contents. This image is passed to processor  22  (S 220 ) as is a conveyor position indication signal from position indicator  32  (S 222 ). The received image of the products  26  (and the vines  30 ) on the tray  28  allows the processor to determine the co-ordinates of a target area for labelling a product (i.e., the processor determines this target area relative to a frame of reference). Based on the determined target area, the processor determines which labeller  12  has a transverse position over conveyor  16  which is within the transverse extent of this target area. This labeller is chosen to label the product (S 224 ). For example, the processor  22  may determine that a target area of product  26   a  can be hit by labeller  12   h  of bank  18   d  and so choose labeller  12   h  for labelling product  26   a . Similarly, the processor may determine that labeller  12   b  of the upstream bank  18   u  should label product  26   b . The distance between the imaging station and each bank  18   u ,  18   d  of labellers is pre-defined and stored in the processor  22 . With knowledge of this, the movement of the conveyor, and the image of the products on the tray, the processor may determine when the target area of any product  26  on the tray  28  will reach the label pick-up station  70  of each bank  18   u ,  18   d  of labellers. Having chosen a labeller  12  for a given product  26 , the processor  22  can then time the sending of an activation signal to stepper motor  44  of the chosen labeller so that a label is applied to the given product (S 226 ).  
         [0034]    More particularly, the activation signal sent by the processor to stepper motor  44  advances the stepper motor  44  by one step to move a bellows  160  which had previously been loaded with a label through the label applying station. While moving through the label applying station, the bellows  160  registers with slot  120  in core  110  thereby coupling the source of positive air pressure to the air diffuser  140  of the bellows  160 . As air attempts to push out of the air diffuser into the bellows, air is initially blocked from exiting central opening  146  in the snout  144  of the air diffuser in view of disk  166  of the bellows blocking this opening. Consequently, initially, most air is directed out of the side openings  148  of the snout  144 . This air fills the vacuum in the bellows. Meanwhile, the air pressure will seat disk  166  against the pin holes  164  in the tamping end  162  of the bellows to block these perforations. With the vacuum in the bellows replaced by a positive pressure, the bellows quickly extends until it tamps the product at the labelling station  128 , thereby applying a label to the product. As the tamping bellows moves past the label applying station  128  it is again coupled to a source of vacuum which quickly draws the bellows back to its collapsed position. At the end of the step by the stepper motor  44 , another bellows  160  will have advanced to the label pick-up station  70 . The processor may then cause the stepper motor  84  of the label cassette  50  to advance another label to the label pick-up station in order to load the bellows now at this station (S 228 ), and the process may repeat.  
         [0035]    Processor  22  may be loaded with software from computer readable medium  34  in order to perform the described operations. Computer readable medium  34  may, for example, be a disk, a solid state memory device, or a file downloaded from a remote source.  
         [0036]    From the foregoing, it will be apparent that each step of stepper motor  44  moves one bellows  160  on turret  40  through the label applying station  128  and stops the turret so that another bellows is registered with the label pick-up station  70 . The speed of the stepper motor may be adjusted so that a bellows moving through the label applying station is coupled to the source of positive pressure air for an appropriate length of time.  
         [0037]    In consequence of air pressure initially being communicated to the bellows through the side openings of the air diffuser  140 , the bellows will contain a positive pressure when it begins its tamping motion. This makes the tamping motion faster and more predictable.  
         [0038]    When a magazine  54  of a cassette  50  is spent, the cassette  50  may be removed, re-loaded, and replaced.  
         [0039]    It will be apparent that the processor  22  may control banks of fixed labellers other than tamping labellers  12  in order to select a labeller to apply a label to a product. Thus, in a modified system, bellows labellers  12  may be replaced with piston-type tamping labellers (such as the labellers described in U.S. Pat. No. 5,645,680 to Rietheimer, the contents of which are incorporated by reference herein). In such case, processor  22 , working with camera  24  and position indicator  32 , may send activation signals to the piston-type tamping labellers. Further, where the products were such that a wiping labeller would suffice, bellows labellers  12  could be replaced by labellers which wipe a label onto a product.  
         [0040]    While the labelling apparatus  10  has been illustrated as having two banks of labellers, with sufficiently narrower labellers, one bank may suffice. Further, to provide a smaller granularity between transverse positions of the labellers, additional banks of labellers could be provided, with each labeller having a smaller transverse offset from transversely adjacent labellers.  
         [0041]    Where the conveyor position indicator is simply a timer, it may be incorporated in the processor  22 .  
         [0042]    Although the stepper motors  44 ,  84  have been described as being electronically controlled by processor  22 , alternatively, they could be mechanically, or electro-mechanically controlled. For example, an overhead deformable finger could be located at a fixed position upstream of each labeller such that the finger is deformed when a product contacts it, resulting in a microswitch temporarily closing. This could activate a timer which, when it times out, sends a signal to the associated labeller causing it to execute a tamping operation and re-load a bellows with a label. Once the timer times out, it is re-set. If the conveyor speed was fixed, each timer could be loaded with an appropriate value based on this speed and the distance the finger was positioned upstream of the associated labeller.  
         [0043]    Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims.