Abstract:
A tamp pad for a label applicator permits use of a single, reconfigurable pad for use with labels of different sizes. Such a pad is used in a label applicator of the type for separating labels from a continuous carrier strip and carrying the labels to and applying the labels to an object positioned at the applicator. The tamp pad includes a first surface configured to receive a label and secure the label thereto by a vacuum. The first surface has a plurality of vacuum openings arranged in at least two series of openings. Each of the openings in a series is aligned with one another and the openings of each series are spaced from the openings of each other series. A second surface has a vacuum channel and at least two depending sub-channels formed therein. The vacuum and sub-channels are configured for receipt of a blocking element to prevent communication of the vacuum through a selected one of the series of openings. One or more blocking elements are configurable to prevent communication of the vacuum through those vacuum openings uncovered by the label received on the pad, without significant loss of vacuum through the uncovered vacuum openings.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a label printer applicator. More particularly, the present invention pertains to a tamp pad for a label printer applicator that uses web fed labels and applies those labels to a series of objects.  
           [0002]    Automated label printer applicators or label machines are well known in the art. Such a machine feeds a continuous web of label material (which web material includes a carrier or liner and a series of discrete labels adhered to the liner at intervals along the liner), removes the labels from the liner and applies the labels to the objects. In many such machines, the label is also printed by the device, prior to separation from the liner and application to the objects.  
           [0003]    Known label machines include, generally, a supply roll on which the web is wound. The web is fed from the supply roll around a plurality of rollers and enters a printing head. In the printing head, indicia are printed on to the individual labels. The web exits the print head and the labels are separated from the liner and are urged into contact with a tamp pad.  
           [0004]    The tamp pad is, typically, a vacuum assisted assembly that holds the individual labels and moves the labels into contact with the objects onto which they are adhered. Tamp pads are typically designed to apply a predetermined or desired force upon application of the label to the object. The force used to apply the label can be varied depending upon the object. For example, while a relatively larger force can be used to apply a label to a heavy gauge shipping carton, a much lesser force must be used when applying a label to, for example, a bakery carton.  
           [0005]    Subsequent to separating the labels from the liner, the liner is accumulated onto a rewind or take-up roll for subsequent disposal. The driving force for moving the web through the label machine is provided by a motor that drives supply roll while the driving force for collecting the liner is provided by a motor that drives the take-up roll.  
           [0006]    Labeling machines are generally part of a high-speed overall processing system. As such, it is desirable to be able to detect various conditions of the supply roll, such as a low label level, few labels remaining or a no labels remaining level. In one known supply roll level sensing arrangement, an optical sensor is mounted adjacent the supply roll. The sensor is mounted so that the point at which a particular, given condition is sensed can be mechanically adjusted, such as by a two-position block or turn screw. A separate sensor in this arrangement is required for label out.  
           [0007]    One drawback to this arrangement is that a typical mechanical mounting limits the range to which the settings can be adjusted. As such, it may be found during operation that it is desirable to set a label out or low label condition outside of the permitted range. In addition, many labels use material that has a somewhat reflective nature, and the reflectiveness of the label material can adversely effect the adjustment as well as the sensing capabilities of many such optical sensors.  
           [0008]    Another known level sensing arrangement uses a mechanical wheel that rides on the edge of the supply roll. This system provides a continuous sensing, rather than set point sensing conditions, to, for example, indicate low and/or label out conditions. However, in order to accommodate labels having various lengths, the mechanical changes required in the sensing arrangement can be quite difficult to accomplish.  
           [0009]    Still another condition sensing device uses an ultrasonic transducer to detect a variety of low and label out conditions. Such ultrasonic devices require considerable and sometimes complex set up times in order to properly calibrate the sensor. Additionally, these sensors typically suffer from performance degradation with changes in temperature and humidity.  
           [0010]    In operation of a label machine, it is necessary to properly tension the liner to create optimal peel tension for separating the label from the liner backing. Such tension controls also control the windup or take-up of the waste liner onto the take-up roll.  
           [0011]    Known machines utilize a number of different arrangements for creating the proper tension on the liner. In one such arrangement, the rewind roll includes a clutch to allow the motor drive to “slip” once a desired tension is achieved. While such an arrangement works well, the clutch requires initial tension adjustment as well as correction over time as the clutch wears. In that clutches are by nature wear-susceptible components, such clutches must be replaced during the course of operation of the machine. Typically, clutch replacement is a fairly labor-intensive undertaking and requires that the machine be taken out of service for an extended period of time.  
           [0012]    In addition, a clutch can be set at a single fixed tension value. However, in order for the liner tension to remain constant as the roll size grows or shrinks, the clutch tension must be changed with a change in the roll diameter.  
           [0013]    Another known arrangement for creating proper tension uses a dancer arm with a limit switch. In such an arrangement, the rewind motor is controlled to operate when the arm moves away from a set point, which set point is determined by a spring tension. In such an arrangement, the motor is either on or off with the position of the limit switch. Typical motors are AC induction-type motors.  
           [0014]    One drawback to this arrangement is that “spikes” in the tension of the liner are observed when the motor turns on or off. In that the motor is either on and running at a particular speed, or off, it has been found that as the motor accelerates and tension increases, the desired tension set point is over-shot. This can result in tension spikes which can cause the liner to break and/or print “stretching”.  
           [0015]    Also in known machines, in applying the label to the product or object surface, it is desirable to apply the label at a consistent force without taking into account changes in the product surface distance, reflectivity or tamp pressure. As set forth above, the label is separated from the liner and is held on the tamp pad. The label remains on the pad until the target object is in line with the pad. A tamp cylinder then extends to move the tamp pad into contact the object surface to apply the label to the surface. At the completion of the extension stroke, the cylinder returns the pad to the home or rest position at which time a subsequent label can be fed onto the tamp pad.  
           [0016]    It is desirable to transfer the label and apply the label to the product surface at a relatively high rate of speed. As such, the transfer process inherently controls the throughput of the label machine. A number of methods are known for controlling the application of the label to the product or object surface in order to maintain high rates of throughput. One straightforward method uses a timer (through hard wiring, such as relays or through software), to return the cylinder from the extended position to the home position based upon a predetermined duration of time. While this method and arrangement is relatively straightforward, it does not compensate for varying product distance. As such, the tamp pad may not reach a shorter product, or conversely, the force may be too great for applying a label to a larger object, in which instance the force of the tamp pad could deform the product or jam the cylinder.  
           [0017]    Another tamp pad control arrangement uses optical sensors that sense the product as the tamp cylinder is extending. Difficulties have been encountered with these optical sensors when used in connection with products having non-reflective or other than flat surfaces. In addition, because of the wiring and/or circuitry required on the moving tamp pad, mean time between failures has been shown to decrease, thus requiring maintenance and/or repair more frequently than acceptable.  
           [0018]    Still another arrangement uses contact plates or mechanical pressure switches to sense pressure. In such an arrangement, the cylinder is returned from the extended position to the home position without a time delay, based upon a sensed pressure. These arrangements measure the pressure within the cylinder chamber and reverse direction of the cylinder upon reaching a set, high pressure point.  
           [0019]    Typically, in these arrangements, the contact plates require a fairly significant force to perform the switch-over function, that is to sense the increased pressure in the cylinder and reverse the cylinder direction. In addition, these mechanical components add significant weight to the tamp pad which increases the time required to change direction. These arrangements typically result in a high force of application on the product surface. As with the other arrangements, this arrangement often requires operator adjustment and frequent maintenance in order to maintain the equipment in proper operating condition.  
           [0020]    The tamp pads are configured such that a label is transferred onto the pad after it is separated from the liner with the non-adhesive side of the label contacting an impact plate (on the front side of the pad). The label is held on the plate and the tamp pad is extended toward the product surface for application of the label. In a typical arrangement, a vacuum is used to secure the label to the impact plate. Typical impact pads are formed from a low friction material having a plurality of vacuum openings formed therein. Vacuum channels are formed in the rear of the plate.  
           [0021]    The plate is mounted to a mounting plate (the rear of the tamp pad) through which a vacuum port provides communication from a vacuum source to the rear of the impact plate. A vacuum is drawn through the vacuum openings to secure the label to the impact plate after separation from the liner and prior to application to the object surface.  
           [0022]    Desirably, label machines are configured for accepting and applying a wide variety of label sizes. To this end, tamp pads must be configured for each of the different label sizes that may be used in a particular machine. The pads must be changed out each time the label size is changed. It has been found that use of improper pad sizes can adversely effect operation of the machine. For example, if a label is smaller than the area encompassed by the vacuum openings, the vacuum will tend to draw through those openings surrounding the label. As such, the label may not be properly secured to the tamp pad. As a result, the label can tend to slip from the pad or be misapplied to the object.  
           [0023]    To this end, label machines are often supplied with a variety of different tamp pad sizes to accommodate label of different sizes. This increases costs as well as the time necessary for machine set up. Other arrangements use standard backing plates or mounts, but use a variety of rubber or similar material faceplates that can be punched out for the particular label dimensions. This, again, lacks the ability to reconfigure face pads that have been punched for a desired application.  
           [0024]    Accordingly, there exists a need for an improved label printer applicator that provides a ready count or indication of the one or more desired levels of labels remaining on the supply roll. Desirably, such indication can be easily changed, and can further be used to control operation of the machine. Such a printer applicator also includes an assembly to control the movement and timing of the tamp pad with respect to applying labels to the surface of objects. Desirably, such an assembly permits applying labels to objects having varying heights or distances from the tamp pad home position, while taking into consideration the force at which the label is applied. Most desirably, such an assembly is self calibrating to take such height differences as well as changes in compressed air supply into account in applying the labels.  
           [0025]    In such a machine, the tamp pad is configured to permit the use of different sizes of labels without the need to change-out pads for each label size. Such a machine also uses a novel rewind assembly and drive to provide proper tension on the liner to prevent over tensioning (and possible breakage), while providing sufficient tension to peel the labels away from the liner on which they are carried.  
         BRIEF SUMMARY OF THE INVENTION  
         [0026]    A label applicator of the type for separating labels from a continuous carrier strip and applying the labels to an object positioned at the applicator includes a supply roll and a rewind roll. The supply and rewind rolls are driven by motors for moving the strip through the applicator.  
           [0027]    The applicator includes a supply disk positioned coaxially on the supply roll. The supply disk has a plurality of equally spaced openings therein. A sensor senses the passing of the supply disk openings. A counter counts the openings passing the sensor. The applicator includes means for determining a predetermined level of labels remaining on the supply roll by counting the openings.  
           [0028]    The applicator includes a tamp pad assembly for moving the labels into contact with an object at the applicator. The assembly includes a tamp pad cylinder having a compressed gas inlet for extending the cylinder and a compressed gas inlet for retracting the cylinder. A pressure transducer is mounted in communication with the compressed gas extension inlet for measuring a pressure in the cylinder. The tamp pad assembly includes means for controlling movement of the cylinder between an extended position and a retracted position including input means from the pressure transducer.  
           [0029]    A tamp pad for use with the applicator permits use of a single, reconfigurable pad for use with labels of different sizes. The pad has a plurality of vacuum openings formed therein. The vacuum openings are arranged in at least two series of openings. Each of the openings in a series is aligned with one another. The openings of each series are spaced from the openings of each other series.  
           [0030]    The tamp pad has a vacuum channel formed in a side thereof and at least two depending sub-channels in communication with the vacuum channel. The vacuum sub-channels are configured for receipt of a blocking element to prevent communication of a vacuum through a selected one of the series of openings. That is, the one or more blocking elements are configurable to prevent communication of the vacuum through those vacuum openings uncovered by the label received on the pad, without significant loss of vacuum through the uncovered vacuum openings.  
           [0031]    In a current embodiment, the tamp pad includes an impact plate for carrying the labels and a mounted plate to which the impact plate is mounted. The impact plate has a first side and a second side generally coplanar with the first side. The vacuum openings are formed in the first side of the impact plate and the vacuum channel and sub-channels are formed in the second side of the plate. A vacuum port is formed in the mounting plate to provide the vacuum to the vacuum channel.  
           [0032]    In a preferred arrangement, the blocking element is formed from a moldable, resilient material, such as silicone rubber.  
           [0033]    The tamp pad defines a leading edge and a trailing edge. The leading edge has a series of vacuum openings formed therein. The trailing edge has a plurality of series of openings formed therein. Each of the series of openings formed in the trailing edge is formed equidistant from its adjacent series of openings.  
           [0034]    The improved applicator includes a rewind assembly having a motor, a biased pivoting arm and a sensing assembly cooperating with the pivoting arm. The sensing assembly senses the presence or absence of a sensed element as the pivoting arm moves from a first home position to a position other than the home position. The sensor is operably connected to the rewind roll drive so as to actuate the motor upon moving the arm toward the home position.  
           [0035]    These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0036]    The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein:  
         [0037]    [0037]FIG. 1 is a front view of a label printer applicator embodying the principles of the present invention;  
         [0038]    [0038]FIG. 2 is an enlarged illustration of the tamp pad assembly of the printer applicator showing the separation blade and tamp pad;  
         [0039]    [0039]FIG. 3 is an enlarged illustration of the rewind assembly dancer arm and the rewind tension sensor assembly;  
         [0040]    [0040]FIG. 4 is an illustration of the print head and shows the path of the web, labels and liner through the printer applicator;  
         [0041]    [0041]FIG. 5 is an illustration of the rear of the printer applicator showing various compressed air valves (solenoid valves) for controlling the pneumatic portion of the machine;  
         [0042]    [0042]FIG. 6 is a graphic illustration of the supply roll encoder disk and sensor;  
         [0043]    [0043]FIG. 7 is a graphic illustration of the tamp pad cylinder assembly and air supply arrangement;  
         [0044]    [0044]FIG. 8 is a plot of the pressure as measured by the pressure transducer along the ordinate (y-axis) of the plot and time/extension of the cylinder shown along the abscissa (x-axis) of the plot;  
         [0045]    [0045]FIG. 9 is a further illustration of the rewind assembly dancer arm and the rewind tension sensor assembly, as shown in FIG. 3;  
         [0046]    [0046]FIG. 10 is an exploded view of a tamp pad embodying the principles of the present invention;  
         [0047]    [0047]FIG. 11 is a front view of the tamp pad of FIG. 10 showing the vacuum openings and the vacuum channels and sub-channels in phantom lines, and showing, in partial views, various sizes of labels positioned on the pad; and  
         [0048]    [0048]FIG. 12 is a cross-sectional view taken along line  12 - 12  of FIG. 10, showing the blocking strips positioned in the tamp pad vacuum sub-channels. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0049]    While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated.  
         [0050]    It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein.  
         [0051]    Referring now to the figures and in particular, to FIG. 1 there is shown generally an automatic label printer applicator or label machine  10 . The machine  10  includes a frame or stand  12  and is positioned above objects (not shown) onto which labels L (see, e.g., FIG. 11) are placed. The frame  12  has mounted thereto a supply or unwind roll  14 , a print head  16 , a tamp pad assembly  18  and a take-up or rewind roll  20 .  
         [0052]    A web indicated generally at W (which includes a backing or liner strip N on which discrete labels L are adhered) is fed from the supply roll  14  and traverses through the print head  16 , in which indicia are printed on the individual labels L. The labels L are then separated from the web W and are dispensed to a tamp pad  22 . A tamp pad cylinder  24  (having the tamp pad  22  mounted thereto) extends to apply the label L to the surface of the object. The liner N, after the labels L have been removed, is then wound onto the take-up or rewind roll  20 . The operation of the label machine  10  is controlled by a controller  25  mounted local to (or on) the machine  10 .  
         [0053]    In order to monitor the “level” of labels L remaining on the supply roll  14 , the machine  10  includes a supply roll level sensing assembly  26 . Referring to FIGS. 3 and 6, the sensing assembly  26  includes an optical slot sensor  28  and a series of slots or holes or openings  30   a,b,c  . . . formed in the supply roll disk  32 . In a present arrangement, the holes are formed in the supply roll inner disk  32 , beyond the periphery of the web W wound on the roll  14 . The assembly  26  is configured to monitor the level or quantity of labels L on the supply roll  14  and to generate signals (for indication) corresponding to a label low supply, label out and “early out”. In the present assembly  26 , a single sensor  28  can be used to provide these three indicating functions.  
         [0054]    The assembly  26  utilizes the sensor  28  and holes  30   a,b,c  . . . formed in the supply roll disk  32  in an encoder arrangement. In printing or advancing a label, the number of holes  30   a,b,c  . . . moving passed the sensor  28  is counted. As the label L is fed from the machine  10 , the accumulated count, in conjunction with the label length, is maintained in memory in the controller  25 . The controller  25  calculates the diameter (radius) of the remaining label roll by use of the equation below:  
           R= [( L   L )( T )]/[2π( T   acc )] 
         [0055]    Where:  
         [0056]    R=roll radius;  
         [0057]    L L =the distance in inches of the label length;  
         [0058]    T=the number of transitions or holes counted in one revolution of the supply disk; and  
         [0059]    T acc  is the number of transitions counted when a label was printed.  
         [0060]    As the machine  10  begins printing a label L, the supply roll  14  (and thus the disk  32 ) rotates. As the disk  32  turns, the sensor  28  counts the number of transitions or slots  30   a,b,c  . . . . If the supply roll  14  does not rotate, the system enters the “early out” condition. In this condition, the machine  10  is allowed to run down to the last few labels L without transporting the end of the liner N (which includes an adhesive bonding material to secure the liner N to the core) through the printer  16 . As will be recognized by those skilled in the art, it is undesirable to transport this portion of the liner N through the print head  16  as damage and/or premature wearing of the print head  16  may occur. Once the supply roll  14  remains stationary for a predetermined period (during which a preset number of labels L is printed), the machine  10  enters “label out” status and shuts down.  
         [0061]    It has been found that a number of advantages are achieved using the present sensor assembly  26  arrangement. First, variable set positions for the supply roll  14  level can be established within the controller  25  merely by setting a predetermined supply roll  14  “radius”. For example, with a proper operator interface, set point positions or conditions can be established and “set” through operator accessible screens and the like. This permits the controller  25  to maintain the particular label and/or operating information within memory for ready recall and reprinting of like labels. In addition, the controller  25  can be configured to allow password only access to the set points within the control system.  
         [0062]    Advantageously, the present sensor arrangement  26  uses a sensor  28  that does not require calibration. That is, the light sensor  28  and “holes”  30   a,b,c  . . . within the disk  32  are set upon installation. No changes in the position of the sensor  28  relative to the holes  30   a,b,c  . . . are required. As such, no field required changes or adjustments are necessary. In addition, such an arrangement is essentially impervious to environmental changes. That is, changes in humidity and/or temperature in the workplace environment have little to no impact on the overall operation of the sensor assembly  26  arrangement.  
         [0063]    As will be appreciated by those skilled in the art, no mechanical adjustments are required for setup. A senor block  34  is mounted to a base plate  36  and the encoder or supply roll disk  32  is permanently attached to a supply roll hub  38 . As such, once established at a fabrication plant, the machine  10  can essentially be installed and started up without adjustment or calibration.  
         [0064]    Referring to FIGS. 1 and 4, and continuing through the machine  10 , the web W traverses from the supply roll  14  over one or more guide rollers  40  and enters the print head  16 . As seen in FIG. 4, in the print head  16 , the web W is aligned by one or more guides  42  or rollers  44  and passes through the printer  46 . Indicia are printed on the label L in accordance with known methods, using known printing techniques. For example, indicia can be imprinted on the label L by transfer from a print ribbon. Alternately, those skilled in the art will recognize the various types of contact and non-contact print devices that can be used.  
         [0065]    Referring to FIGS. 2 and 4, after exiting the printer  16 , the web W traverses to a separating blade  48 . At the separating blade  48 , the web W is rerouted (i.e., in a sharp angled turn, as indicated generally at  50 ) to begin separating the label L from the liner N. The liner N then traverses in a direction opposite that of the continued movement of the label L. Essentially, the liner N is pulled away from the label L, and the label L traverses on to the tamp pad  22 .  
         [0066]    Referring now to FIGS.  1 - 2  and  7 , the tamp pad  22  is part of the overall tamp assembly  18 . The tamp assembly  18  includes generally the tamp pad  22  and the tamp pad cylinder  24 . In a present embodiment, the cylinder  24  is a pneumatic cylinder. The tamp pad  22  (which will be discussed in detail below) is mounted to the cylinder  24  and moves with extension and retraction of the cylinder  24  between the label L applying or extended position and a label L receiving or home position (FIG. 2). These positions are the positions at which the label L is applied to the product surface and the position at which the label L is moved onto the tamp pad  22  after separation from the liner N.  
         [0067]    In a present arrangement, a dual action cylinder  24  is used. That is, air (or a like compressed gas) pressure is applied to one side  52  of a piston  54  in the cylinder  24  to extend the cylinder  24  and air pressure is applied to an opposing side  56  of the piston  54  to retract the cylinder  24 . Compressed air supply lines  58 ,  60  extend from a compressed air source (not shown) to inlets at the opposing sides  52 ,  56  of the cylinder  24  to move the cylinder  24  between the extended and home positions.  
         [0068]    In a current embodiment of the label machine  10 , a pressure transducer  62  is positioned in the supply line  58  to the piston  54  for supplying air to move the piston  54  to the extended (label L applying) position. The transducer  62 , in conjunction with the controller  25  is used to monitor the varying pressure in the cylinder  24  body. The system is configured to recalibrate during each extension cycle to maintain an optimal threshold level. In this manner, changes in pressure from the pressure source or changes in the tamp cylinder  24  pressure set point are taken into consideration during each recalibration cycle. Moreover cylinder  24  body wear and debris within the orifices (not shown) are likewise compensated for by measuring the pressure profile of the air filling the cylinder  24 .  
         [0069]    [0069]FIG. 8 graphically illustrates one cycle of the piston  54  from the retracted position through the extended position. This figure is a plot of the pressure P as measured by the pressure transducer  62  along the ordinate of the plot (y-axis) and time (t) or extension (E) shown along the abscissa of the plot (x-axis).  
         [0070]    Upon receipt of a signal from the controller  25  to apply a label L, a valve  64  is opened to apply pressure to the extension inlet port side  52  of the cylinder  24 , and the tamp pad  22  moves to the extended position. At this point in time, the cylinder  24  volume is small and the initial pressure inlet peaks (as indicated at  66 ). The pressure initially spikes in that the cylinder  24  must be moved from the home position. As such, the rate of change of volume is less than the rate of change of pressure within the cylinder  24 . The peak pressure (as at  66 ) measured by the transducer  62  is used to determine a maximum pressure or tamp pressure value setting for the system  10 .  
         [0071]    As the cylinder rod  68  begins to move at an increased rate (in that the initial inertia of the system is overcome), the pressure begins to drop (as indicated at  70 ) within the cylinder  24 . It has been found that the pressure drops to a level (as indicated at  72 ) that is equal to the rate of volume expansion or rate of air filling the space behind the rod plate  74 . The transducer  62  monitors and measures the lowest point of pressure (as indicated at  76 ) for the system and provides a signal to the controller  25  for determining the optimal trigger threshold point for return.  
         [0072]    The cylinder  24  continues to extend as the pressure slowly begins to increase (as indicated at  78 ). This is due to the velocity of the cylinder  24  reaching an essentially steady state, while air continues to be fed into the cylinder  24 . Although the pressure increases, the increase is significantly small so as to not cause a triggering of the cylinder return.  
         [0073]    Once the tamp pad  22  contacts the product surface, there is an abrupt increase or positive change in pressure (as indicated at  80 ) in the cylinder  24 . Because the volume of the cylinder  24  is fixed, it can no longer extend further. As a result, the pressure in the cylinder  24  increases beyond the trip point established by the proceeding events. Upon reaching this point, the cylinder  24  is retracted to the home position by inlet of the retraction air (through piston side  56 ), and the venting of the extension side  52  of the cylinder  24 .  
         [0074]    The present arrangement has a number of advantages over known tamp pad pressure return arrangements. First, a relatively inexpensive “off the shelf” pressure transducer  62  is used to monitor the pressure in the cylinder  24 . The transducer  62  generates signals that are used to provide input for automatic control and calibration of the tamp process. In addition, the process calibrates each cycle. In this manner, close control is maintained over the tamp process.  
         [0075]    Moreover, the contact force, that is the force of the tamp pad  22  on the object surface is consistent regardless of fluctuations in inlet  58  pressure and user set point adjustments. In addition, as set forth above, the force is established regardless of environmental conditions (e.g., temperature and humidity fluctuations).  
         [0076]    Also, unlike many known tamp sensing arrangements, varying product distances can be accommodated by the present pressure sensing arrangement. That is, packages of different “heights” can have labels applied thereto using the present label machine  10 , because the point from which the tamp pad  22  returns is determined by sensing the pressure spike and trough and setting the return pressure accordingly.  
         [0077]    Moreover, it has been found that the use of a pressure transducer  62  in the inlet line  58  does not adversely affect the throughput of the label machine  10 . That is, even though the transducer  62  may not react instantly, it has been found that the sensitivity of the transducer  62  does not adversely affect the speed of the packaging line.  
         [0078]    With respect to the tamp pad  22 , a pad in accordance with the present invention is illustrated in FIGS.  10 - 12 . The tamp pad  22  is configured to allow changing label sizes quickly and to allow use of a single pad with multiple size labels. The tamp pad  22  includes a rear mounting plate  84  having a mounting block  86  attached thereto. A vacuum inlet  88 , such as the illustrated vacuum elbow fitting is mounted to the rear mount plate  84 .  
         [0079]    An impact plate  90  is mounted to the rear mounting plate  84 . The impact plate  90  is that plate onto which the label L is transferred and is carried to the object surface for adhering to the object. The impact plate  90  is mounted to the rear mounting plate  84  by a plurality of fasteners  92 , such as the illustrated flat head machine screws. The impact plate  90  is configured having counter-bored openings (as shown at  94 ) so that the screws  92  rest flush or below the surface  96  of the impact plate  90 .  
         [0080]    The impact plate  90  includes a first or leading end  98  (which is that end closest to the print head  16 ) and a trailing end  100  (which is that end farthest from the print head  16 ). A plurality of vacuum openings or through holes  102   a,b,c  . . . are formed in the impact plate  90  at the leading end  98  (the leading end series of openings). The series of openings  102  extend along the width D of the plate  90  or in the direction transverse to the direction (indicated by the arrow at  104 ) in which the labels L move on to the plate  90 .  
         [0081]    The trailing end  100  of the plate  90  includes a plurality of series of openings  106   a,b,c  . . . . Each of the series of openings  106  extends generally parallel to the leading end series of openings  102 . These openings  106 , like the leading end openings  102 , are transverse to the direction  104  of movement of the label L on to the pad  90 . It is through these openings  102 ,  106  that vacuum is communicated to secure the non-adhesive side of the label L to the tamp pad  90  from the time that it is separated from the liner N until it is applied to the product or object surface. Intermediate series of openings such as those indicated at  103 ,  105 ,  107  can also be formed in the pad  22 .  
         [0082]    The impact plate  90  includes a vacuum channel  108  formed in a rear surface  110  thereof. The vacuum channel  108  includes a main longitudinal channel  112  that is in communication with the vacuum inlet  88  on the mounting plate  90 . The longitudinal channel  112  extends essentially along the length L of the plate  90  from the leading end vacuum openings  102  to the trailing end vacuum openings  106 . There are no vacuum openings formed in the main longitudinal channel  112 .  
         [0083]    The leading and trailing end vacuum opening series  102 ,  106  are in communication with sub-channels  114 ,  116 , respectively, that extend from the main vacuum channel  112 . Each sub-channel  114 ,  116  essentially depends from the main vacuum channel  112 . A single series of vacuum openings (e.g.,  102   a,b,c  . . . ) is formed so as to communicate with a discrete sub-channel (e.g.,  114 ). In this manner, the leading edge vacuum openings  102  are formed in a first sub-channel  114  and each series of trailing edge vacuum openings ( 103 ,  105 ,  107  and  106 ) is formed in a discrete trailing edge vacuum sub-channel ( 118 ,  120 ,  122  and  116 , respectively).  
         [0084]    As will be recognized by those skilled in the art, when the vacuum openings  102 ,  103 ,  105 ,  106 ,  107  extend over an area that is greater than the size of the label L that is secured thereto, the vacuum tends to be drawn through the openings over which a portion of the label L does not lie. That is, the vacuum tends to be drawn through the path of least resistance which is those vacuum openings that are open to atmosphere, rather than those over which the label L lies.  
         [0085]    To this end, a present tamp pad  22  includes a plurality of blocking strips  124  that can be laid in each of the sub-channels  116 - 122  along the entire length of the sub-channel  116 - 122  or a portion of the sub-channel  116 - 122 . The strips  124  are configured so as to block or prevent communication of the vacuum from the main channel  112  into those vacuum openings lying along the blocked sub-channel. In this manner, a desired series of openings and/or portions of series of openings can be configured to remain open while other series and/or portions of series of openings can be blocked. In a present pad, the strips  124  are formed from a silicone rubber that is readily placed and held in a desired sub-channel  116 - 122 .  
         [0086]    This arrangement provides for free communication of the vacuum through those openings that correspond to a given label size. Thus, if a small label is to be used with the tamp pad  22 , the impact plate  90  can be removed, strips  124  can be laid in the sub-channels that are outside of the label footprint (e.g.,  116 - 120  as appropriate) and the impact plate  90  can be remounted to the mounting plate  84 . Thus, when a vacuum is drawn through the vacuum inlet  88  in the mounting block  86 , the vacuum is communicated only to those vacuum openings that correspond to a desired, particular label. This configuration permits reconfiguring a single tamp pad  22  for use with a variety of sizes of labels L by reconfiguring the layout of the blocking strips  124 .  
         [0087]    It has been found that a tamp pad  22  in accordance with the present invention permits the use of a variety of label sizes with a single tamp pad  22 . For example, as noted below, tamp pads  22  having the dimensions as shown in the first column can be used with labels L ranging from about the size shown in the second column (smallest label L size) to a label L size about as large as that shown in the third column (largest label L size).  
                                           APPROXIMATE   APPROXIMATE       PAD SIZE   SMALLEST LABEL SIZE   LARGEST LABEL SIZE                   2″ × 2″ pad   1″ × 1″   2″ × 2″       2″ × 4″ pad     1″ × 2.5″   2″ × 4″       2″ × 6″ pad     1″ × 4.5″   2″ × 6″       2″ × 8″ pad     1″ × 6.5″   2″ × 8″       2″ × 13″ pad     1″ × 8.5″    2″ × 13″       4″ × 2″ pad   2.5″ × 1″     4″ × 2″       4″ × 4″ pad   2.5″ × 2.5″   4″ × 4″       4″ × 6″ pad   2.5″ × 4.5″   4″ × 6″       4″ × 8″ pad   2.5″ × 6.5″   4″ × 8″       4″ × 13″ pad   2.5″ × 8.5″    4″ × 13″                  
 
         [0088]    The tamp pad  22  is configured so that the blocking strips  124  are readily removed and/or replaced in the sub-channels  116 - 122 . To reconfigure the tamp pad  22 , the fasteners  92  or mounting screws that secure the impact plate  90  to the mounting plate  84  are removed. The strips  124  can then be inserted or removed in those sub-channels  116 - 122  or portions of sub-channels  114 - 122  that require blocking off for the particular label L size. At least a portion of the first sub-channel  114  always remains unblocked. However, if a label L width D is smaller than the maximum that can be accommodated for that particular pad  22 , a portion of the sub-channel  114  can be blocked. In addition, it has been found that the channel utilized for the particular label&#39;s furthest length edge should also remain unblocked.  
         [0089]    It has been found that present configuration permits reducing the number of tamp pad combinations significantly. For example, in a present application, it has been found that the number of tamp pad combinations can be reduced from over 900 to about 10. The present configuration also permits an end user to use the same pad  22  even if their label L size changes within a preset range. In addition, the user (customer) can readily reconfigure the tamp pad  22  with minimal downtime and without significant skilled labor.  
         [0090]    Still another advantage of the present label machine relates to the rewind or take-up arrangement indicated generally at  130 . The rewind arrangement  130 , best seen in FIGS. 3 and 9, is configured to facilitate creating sufficient tension for separating the label L from the liner N as well as to control the wind up of the waste liner N onto the rewind roll  20 . To this end, the rewind arrangement  130  includes the rewind roll  20  onto which the waste liner N is rolled. The roll  20  is driven by a motor  21  that is controlled by the overall machine controller  25 . In a present machine, a servomotor or stepper motor is used for the rewind assembly  130  to provide greater control over the rewind speed as discussed below.  
         [0091]    A present rewind assembly  130  includes a pivoting dancer arm  132  that controls the rewind tension and speed while at the same time reduces slack that may develop in the web W when the label feed begins and the rewind motor  21  starts. To this end, the rewind assembly  130  creates sufficient tension on the liner N to avoid telescoping of the liner waste roll  20  while at the same time creating sufficient (but not too much) tension in the liner N to prevent label L mis-feed and print stretching.  
         [0092]    As shown in FIG. 9, the dancer arm  132  is mounted for pivoting about a pivot  134  located near the rewind roll  20 . The dancer arm  132  cooperates with an upper stop  136  and is biased toward the upper stop  136  position. In a present arrangement, a constant rate spring  138  (FIG. 3) biases the dancer arm  132  to the stop position. A roller  140  is positioned at about an end of the dancer arm  132 , over which roller  140  the liner N travels.  
         [0093]    A sensing assembly  142  cooperates with the dancer arm  132 . In a present arrangement, the sensing assembly  142  includes magnets  144  positioned on the arm  132  between the pivot  134  and the roller  140  and a magnet sensor  146  mounted to the label machine frame  12 .  
         [0094]    The dancer arm spring  138  is a fixed rate spring and thus sets the tension in the liner N in a non-linear fashion. In addition, as set forth above, the rewind roll  20  is controlled by a stepper or servomotor rather than a conventional induction motor. As such, movement of the rewind roll  20  is more closely controlled than would otherwise be possible with a convention induction motor.  
         [0095]    As will be appreciated by those skilled in the art, liner N tension increases as the rewind motor  21  turns. This in turn forces the dancer arm  132  to pivot, thus extending the spring  138 . As the magnets  144  (mounted on the dancer arm  132 ) approach the magnet sensor  146 , the tension is at an optimal range for liner N take-up. However, if the motor  21  continues to turn the rewind roll  20 , tension in the liner N continues to increase and the liner N may eventually tear. In this manner, there is a balancing of motor  21  rotation and dancer arm  132  (height) to control the liner N tension. Conversely, if the motor  21  stops, too much slack may be present in the liner N, and insufficient tension is produced for separating the labels L from the liner N.  
         [0096]    In order to establish the proper tension balance, the rewind motor  21  is controlled to apply a rotation distance proportional to the time elapsed from when the dancer arm  132  leaves the home position. If the dancer arm  132  slowly leaves the home position, the rewind motor  21  speed is increased to bring the arm  132  into position. Conversely, an abrupt change in dancer arm  132  position results in a slow increase in rewind motor  21  speed. This arrangement prevents oscillation (rapid increases and decreases in rewind motor  21  speed) which could otherwise cause tension spikes in the liner N.  
         [0097]    In order to provide proper tension for initial peel of the label L from the liner N, the start of print is accomplished with an increase in rewind motor  21  speed for a predetermined period of time. In carrying this out, tension is increased briefly by forcing the dancer arm  132  beyond the set tension. Continued feed then results in a relaxation of the dancer arm  132  moving toward the home position. This provides the required tension for the initial peel or separation of the label L from the liner N, without continuously over-tensioning the liner N.  
         [0098]    All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically do so within the text of this disclosure.  
         [0099]    In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular.  
         [0100]    From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover all such modifications as fall within the scope of the invention.