Patent Abstract:
An apparatus and laminate allow removal of at least one sub-area of a face layer sheet from a laminate composed of a backing layer with the face layer sheet adhering thereto to leave at least one product area of the face layer sheet in place on the backing layer. The apparatus may comprise a work surface for receiving the laminate thereon; at least one adhesive applicator mounted adjacent to the work surface; an actuator associated with the applicator(s); an actuator controller to cause application of an adhesive to predetermined portions of the waste area(s); a laminator beside the work surface including a supply of carrier web oriented for temporary lamination with the laminate using the applied adhesive; and a delaminator positioned to receive the carrier lamination and delaminate the laminate therefrom with the waste area(s) adhering to the carrier web.

Full Description:
RELATED APPLICATION  
       [0001]     This is a divisional of patent application Ser. No. 10/094,691, filed on Mar. 11, 2002 by Steen B. Mikkelsen entitled “Automatic Waste-Area Removal Method” which was a continuation-in-part of now-abandoned patent application Ser. No. 09/804,344, filed on Mar. 12, 2001 by Steen B. Mikkelsen, entitled “Automatic Waste-Area Removal Method and Apparatus.” 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention is related generally to decal laminate technology, such as is involved in the preparation of one or more decals (e.g., “graphic areas” or “product areas”) which are formed as part of a removable layer of a laminate for later removal and application onto various surfaces. More particularly, the invention relates to the field involving prior removal of waste portions of removable laminate layers, leaving the removable decal in place on the laminate.  
       BACKGROUND OF THE INVENTION  
       [0003]     Many if not most decals are graphics-image-bearing portions (sometimes referred to herein as “product areas,” whether or not they have graphics images thereon) of a removable layer (sometimes referred to herein as a “face layer”) of a laminate. Each such decal laminate typically includes the face layer and a backing layer (or “liner”), the face layer being removably secured to the backing layer by an adhesive. The adhesive is preferential to the face layer, and is used, after removal of the product area(s) from the backing layer, for the adhesive attachment of the product area(s) of the face layer onto the surface intended to be covered—for decorative, signage or any of a multitude of other purposes.  
         [0004]     To facilitate production of product areas (decals) in a form ready for use, it is frequently necessary or desirable to pre-remove the area or areas of the face layer which is/are not product areas from the backing layer of the decal laminate. (These non-product areas of the face layer are often referred to herein as “waste areas.”) Such pre-removal of waste areas leaves the product area(s) on the backing layer—ready to be easily peeled away from the backing layer just prior to use. The pre-removal of waste areas of a face layer, sometimes referred to “sheet-weeding,” greatly facilitates the subsequent removal of product areas (decals) just prior to use.  
         [0005]     (The pre-removal of waste areas, of course, follows slitting or other severing of the product areas from the waste areas, which occurs while the removable layer to be slit or severed is in place on the backing layer. A highly preferred and advantageous method and apparatus for accurate severing around the product area or areas of the face layer of a decal laminate is disclosed in commonly-owned U.S. patent application Ser. No. 09/678,594, filed Oct. 4, 2000, entitled “Method and Apparatus for Precision Cutting and the Like of Graphics Areas from Sheets.”)  
         [0006]     Sheet-weeding is typically carried out by nimble-fingered workers who delicately lift and peel away unused portions of the image-bearing face layer of a decal laminate. This is tedious and time-consuming work. Progress has been made toward automating the sheet-weeding process; despite such efforts, there remains a need for an improved automatic waste-area removal method and apparatus.  
         [0007]     Various automated systems have been devised over the years for facilitating sheet-weeding operations. Among these are the systems and concepts disclosed in the following United States patents: U.S. Pat. No. 5,143,576 (Logan); U.S. Pat. No. 5,277,736 (Logan); U.S. Pat. No. 5,026,584 (Logan); U.S. Pat. No. 4,246,058 (Reed); U.S. Pat. No. 4,786,537 (Sasaki); U.S. Pat. No. 5,695,600 (Goin); and U.S. Pat. No. 4,333,781 (Meulenberg). These prior systems each have certain disadvantages or problems, some of which are set forth below.  
         [0008]     The computer-controlled systems of the Logan patents use complex adhesive materials including microspheres or microcapsules which, when broken by force application, release strong adhesive to allow an overlay sheet to engage and remove portions of a sheet. Such adhesives can be very expensive, and force-activation can be problematic and difficult in high-speed operations.  
         [0009]     The Reed disclosure involves an embossing of areas to be removed in order to weaken their adhesive attachment to the base layer and facilitate removal. However, such embossing tends to be a step which, among other things, may be unacceptable for removal of intricate waste areas or patterns around irregularly shaped decals or product areas.  
         [0010]     The Sasaki disclosure involves removal of an overlayer after a separation is caused by radiation treatment of a radiation-responsive composition. This system is complex and believed not to be suitable for many high-speed production operations.  
         [0011]     The prior systems and disclosures fall short of offering and delivering simple, effective sheet-weeding which is fully suitable for high-speed decal production and similar waste-area removal operations.  
       OBJECTS OF THE INVENTION  
       [0012]     It is an object of this invention, in the field of decal laminate technology, to provide an improved sheet-weeding method and apparatus for prior removal of waste portions of removable laminate layers which overcomes some of the problems and shortcomings of the prior art.  
         [0013]     Another object of this invention is to provide a sheet-weeder and sheet-weeding method which can operate at high speeds.  
         [0014]     Another object is to provide a sheet-weeder which can operate with little or no detrimental effects to the product areas remaining on the laminate.  
         [0015]     Another object of the invention is to provide a sheet-weeding method which more reliably removes all or nearly all of the waste areas of the face layer from the backing layer while more reliably not removing all or nearly all of the product areas.  
         [0016]     Another object of the invention is to provide a sheet-weeding which allows reliable removal of waste areas of the face layer from the backing layer around delicate products areas.  
         [0017]     Still another object of the invention is to provide a sheet-weeder which is simple, efficient and cost-effective.  
         [0018]     Yet another object of the invention is to provide an improved method and apparatus for removal of select areas of less-than-all layers of a laminate which are useful in a wide variety of contexts and applications.  
         [0019]     These and other objects of the invention will be apparent from the following descriptions and from the drawings.  
       SUMMARY OF THE INVENTION  
       [0020]     The invention is a method and apparatus for removing waste area(s) of a face layer from a laminate composed of a backing layer with the face layer removably adhering thereto, while leaving at least one product area of the face layer in place on the backing layer. The sheet-weeding method of this invention includes applying an adhesive on portions of the waste area(s), temporarily adhering the laminate to a carrier surface (of a carrier-surface member) using the adhesive, and separating the laminate from the carrier surface with the waste area(s) remaining on the carrier surface.  
         [0021]     A number of terms used herein are defined at the end of this “Summary” section. Such definitions should be referred to for clarity of understanding.  
         [0022]     In certain highly preferred embodiments, the carrier-surface member is a carrier sheet—most preferably a carrier web. In such embodiments, the adhering step, in which the laminate is adhered to the carrier web or other carrier sheet, such combination is sometimes referred to herein as a “carrier lamination.” In some embodiments, such carrier lamination is discarded with the waste area(s) remaining on it. Suitable carrier web materials include unused newsprint. Embodiments using a carrier web facilitate continuous or nearly continuous sheet-weeding.  
         [0023]     In preferred embodiments of the invention utilizing a carrier web, the process of separating the laminate from the carrier web while leaving the waste areas on the carrier web involves peeling the carrier web away from the laminate. In certain preferred embodiments, it is most preferred that the separating step include the step of pulling the carrier web over a separator edge in tension to initiate separation of the laminate from the carrier web.  
         [0024]     As already indicated, the carrier-surface member is preferably in the form of a carrier web; however, in some embodiments it can be in the form of a fairly large cylindrical roller—sufficient to accommodate various operations therearound. When in the form of a carrier web, the carrier web may be a long continuous two-ended web, such as the newsprint mentioned above, or may be an endless web each portion of which is used and reused. In preferred embodiments in which the carrier-surface member is either an endless carrier web or a large cylindrical roller, the method of this invention preferably includes, after the step of separating the laminate from the carrier surface with the waste areas thereon, the further step of removing the waste areas from the carrier surface and discarding the waste areas, thereby clearing the carrier surface for reuse.  
         [0025]     In certain embodiments of the invention, the adhesive is applied adjacent to the product area(s), preferably only at discrete locations. It is preferred that the adhesive applicator apply a quick-drying liquid adhesive, doing so by shooting the adhesive onto the specific locations of the waste area(s) without applicator contact with the waste area(s).  
         [0026]     Certain preferred embodiments in which a carrier web is used include: unrolling a portion of the carrier web from a roll; performing the laminating of a laminate to the unrolled portion of the carrier web; separating the laminate from the unrolled portion; and thereafter rolling up the carrier web with the waste area(s) thereon.  
         [0027]     In preferred embodiments of this type, the web is moving in a direction along its length at least during the laminating and separating steps. In these embodiments, the product and waste area(s) each have at least one leading-edge portion and at least one trailing-edge portion (see definitions infra), some of the leading-edge portion(s) of the waste area(s) being adjacent to trailing-edge portions of the product areas. In highly preferred embodiments, the adhesive is applied to the leading-edge portion(s) of the waste areas.  
         [0028]     In preferred embodiments, the precise locations of adhesive application are controlled by a computer. Precise locations are determined by what is best to affect separation of waste areas while leaving product areas fully intact on the backing layer.  
         [0029]     The apparatus of this invention includes: a support for the laminate; an adhesive applicator adjacent to the supported laminate; an actuator associated with the applicator; a controller for the actuator to cause application of an adhesive to the waste area(s); a carrier-surface having a carrier surface positioned to receive the laminate with the laminate adhering thereto; and a separator adjacent to the carrier surface to separate the laminate from the carrier surface with the waste area(s) remaining on the carrier surface.  
         [0030]     Certain embodiments of such apparatus also include a stripper for removing the waste area(s) from the carrier surface after the separation has been accomplished. This allows the carrier surface, which is preferably endless, to be reused, and in some cases enhances the continuous nature of the operation.  
         [0031]     Certain preferred forms of the apparatus of this invention include: a work surface on which to receive the laminate; at least one adhesive applicator mounted adjacent to the work surface; an actuator associated with the applicator(s); an actuator controller to cause application of an adhesive to predetermined portions of the waste area(s); a laminator beside the work surface including a supply of carrier web oriented for temporary lamination with the laminate using the applied adhesive; and a delaminator positioned to receive the carrier lamination and delaminate the laminate therefrom with the waste area(s) adhering to the carrier web.  
         [0032]     In certain other highly preferred embodiments of such apparatus, as already indicated by the above discussion of the inventive method, the carrier-surface member is a carrier web. In such embodiments, it is most preferred that the separator include a separator edge positioned so that the carrier web passes under tension over the edge to initiate separation of the laminate from the carrier web.  
         [0033]     In highly preferred embodiments of the invention, the face layer of the laminate has a plurality of registration marks at and about the product area(s) which are used for locating those areas of the laminate to which adhesive is to be applied. More specifically, the apparatus includes a controller (e.g., computer) programmed with information on the product area(s) and the waste area(s) and a sensor mounted adjacent to the work surface and capable of sensing locations of the registration marks and transmitting such information to the controller. The applicator(s) is/are actuated in response to the information about the locations of the registration marks sensed by the sensor and the information on the product area(s) and the waste area(s).  
         [0034]     The laminates for which the method and apparatus of this invention facilitate sheet-weeding operations can be in various forms. For example, the laminates can be in the form of discrete sheets, either large or small, or a laminate may be in the form of a lengthy continuous sheet (web) which extends from a supply roll to a take-up roll. Either way, the laminates to be weeded may have a large number of product areas on it, in a great variety of shapes and sizes, and a great number of waste areas in a variety of shapes and sizes. In other cases, a lengthy continuous laminate web may have one or more rows of identically-shaped product areas such as labels or the like.  
         [0035]     Broadly considered, this invention is a method for removing sub-areas of a face layer from a laminate composed of a backing layer with the sub-areas removably adhering thereto over less than all of the backing layer, and the invention involves: applying an adhesive on portions of the sub-areas; temporarily adhering the laminate to a carrier sheet using the adhesive; and separating the sub-areas from the backing layer by peeling them off with the carrier sheet.  
         [0036]     In certain preferred embodiments of the method of this invention, one waste area has a leading edge portion with a leading edge that includes a lead part and at least one trailing lateral part, and the separating step includes (1) separating the waste area (with the carrier surface, e.g., a carrier sheet in web or other form) from the backing layer along the lead part before the trailing lateral part(s) are separated from the backing layer, thereby creating a chord line spanning the lead part, (2) continuing the separating step until the chord line substantially spans the leading edge portion, and (3) thereafter completing the separating step.  
         [0037]     In such embodiments, it is preferred that the leading edge portion have at least one starter tab along the lead part of the leading edge, the starter tab extending in the direction opposite the weeding direction and having a width less than about 10% of the width of the leading edge portion.  
         [0038]     In a highly preferred embodiment, the leading edge is convex. Preferably, such convex leading edge is a substantially circular arc having a radius greater than half the width of the leading edge portion. Such arc can be very gentle; even if the radius is substantially greater than the width of the leading edge portion to the point that the arc is nearly a straight line, waste area removal is substantially facilitated.  
         [0039]     In certain other preferred embodiments of the method of this invention, in which a product area has a delicate leading edge portion, the waste area includes one trailing edge portion adjacent to the delicate leading edge portion, such trailing edge portion having a force-modifying slit therein which surrounds the delicate leading edge portion and has ends on opposite sides thereof.  
         [0040]     In certain preferred embodiments having delicate leading edge portions, the ends of the force-modifying slit are downstream of the delicate leading edge portion. Preferably, the force-modifying slit is arcuate; the slit may be substantially circular. It is highly preferred that the ends of the force-modifying slit be downstream of the delicate leading edge portion.  
         [0041]     In certain embodiments of the inventive method, a particularly delicate product areas is surrounded by a temporary product area such that the temporary product area is removed from the backing layer at some time following the completion of the automatic weeding process.  
         [0042]     In certain embodiments the apparatus for removing sub-areas of a face layer sheet from a laminate of the type having been formed by removably adhering the face layer sheet to a backing layer, the sub-areas covering less than all of the backing layer, the face layer sheet having a plurality of registration marks at and about the sub-areas, comprises a sensor that senses locations of the plurality of registration marks; an adhesive applicator that automatically applies adhesive to portions of the sub-areas in response to the sensor sensing locations of the plurality of registration marks; a carrier-surface member having a carrier surface that receives the laminate with the laminate adhering thereto via the adhesive; and a separator adjacent to the carrier surface that separates the laminate from the carrier surface with the waste area(s) remaining on the carrier surface.  
         [0043]     In certain embodiments, the separator peels the sub-areas from the backing layer. In certain embodiments, the apparatus further comprises a controller that actuates the adhesive applicator to apply adhesive on portions of the sub-areas in response to the sensor sensing the locations of the plurality of registration marks.  
         [0044]     In certain embodiments, the applicator is a jet applicator which applies adhesive without applicator contact with the sub-areas. In certain embodiments, the adhesive is a quick-drying liquid.  
         [0045]     In certain embodiments, the carrier surface forms an endless web. In certain embodiments, at least one product area is surrounded by a sub-area, the product area remaining on the backing layer during separation of the sub-area and the backing layer.  
         [0046]     In certain embodiments, the laminate formed by removably adhering a face layer sheet to a backing layer, the laminate for use with an apparatus for removing sub-areas of the face layer sheet from the backing layer, the sub-areas covering less than all of the backing layer, to leave at least one product area of the face layer sheet in place on the backing layer, the laminate comprising the backing layer; and the face layer sheet, the face layer sheet having a plurality of registration marks at and about the sub-areas, the face layer sheet including the sub-areas, each sub-area having a leading edge portion with a leading edge having a lead part, at least one trailing lateral part and at least one starter tab along the lead part, the starter tab extending in the direction opposite a weeding direction and having a width less than about 10% of the width of the leading edge portion. Such a laminate provides that, during removal of the sub-areas from the backing layer, the lead parts are separated from the backing layer before the trailing lateral parts are separated from the backing layer, thereby creating chord lines that span the lead parts before substantially spanning the leading edge portions with removal of the sub-areas progressing along the weeding direction.  
         [0047]     In certain embodiments, each leading edge has two lateral parts, one on each side of the respective lead part. In certain embodiments, each leading edge is convex. In certain embodiments, each leading edge is a substantially circular arc having a radius greater than half the width of the respective leading edge portion. In certain embodiments, each radius is greater than the width of the respective leading edge portion.  
         [0048]     The invention also includes, in combination, a laminate and an apparatus for use with the laminate, the laminate formed by removably adhering a face layer sheet to a backing layer, the face layer sheet having sub-areas covering less than all of the backing layer, the face layer sheet having a plurality of registration marks at and about the sub-areas, the apparatus removing the sub-areas of the face layer sheet from the laminate to leave at least one product area of the face layer sheet in place on the backing layer.  
         [0049]     In such a combination, the apparatus may comprise a sensor that senses locations of the plurality of registration marks; an adhesive applicator that automatically applies adhesive to portions of the sub-areas in response to the sensor sensing locations of the plurality of registration marks; a carrier-surface member having a carrier surface that receives the laminate with the laminate adhering thereto via the adhesive; and a separator adjacent to the carrier surface that separates the laminate from the carrier surface with the waste area(s) remaining on the carrier surface.  
         [0050]     In such a combination the laminate may comprise the backing layer; and the face layer sheet in which each sub-area has a leading edge portion with a leading edge having a lead part, at least one trailing lateral part and at least one starter tab along the lead part, the starter tab extending in the direction opposite a weeding direction and having a width less than about 10% of the width of the leading edge portion.  
         [0051]     Such a combination provides that, during removal of the sub-areas from the backing layer, the lead parts are separated from the backing layer before the trailing lateral parts are separated from the backing layer, thereby creating chord lines that span the lead parts before substantially spanning the leading edge portions with removal of the sub-areas progressing along the weeding direction.  
         [0052]     As used herein, the following terms have the meanings given below, unless the context requires otherwise:  
         [0053]     The term “quick-drying adhesive” refers to a liquid adhesive which, when applied by the applicator, flows in its liquid state easily enough to be applied with a jet applicator or sprayer but which, when applied to the waste areas of the face layer, dries rapidly enough such that it acts properly as an adhesive when it is contacted by the carrier-surface member.  
         [0054]     The term “weeding direction” as used herein refers to the direction in which the weeding progresses along a sheet or roll of materia. More specifically, it refers to the direction of motion of the line along which separation of waste areas from the backing layer occurs. Accordingly, the weeding direction proceeds from “upstream” positions to “downstream” positions.  
         [0055]     The terms “leading edge portion” and “trailing edge portion” pertain, e.g., to portions of areas of the face layer (i.e., portions of the product areas/or portions of the waste areas) in embodiments of this invention in which the carrier surface (e.g., the surface of a carrier web) is moving during the adhering and separating (or “laminating” and “delaminating”) steps of the sheet-weeding process. A leading edge portion of a waste area is a part thereof which is (1) immediately adjacent to and following a product area as determined along lines parallel to the weeding direction or (2) is immediately adjacent to a leading edge of the laminate if such leading edge is part of a waste area of the laminate. A trailing edge portion of a product area is a part of thereof which is immediately adjacent to and ahead of a waste area as determined along lines parallel to the weeding direction. In embodiments not involving a moving carrier web, the terms “leading edge portion” and “trailing edge portion” refer to the order of portions undergoing separation—with a “leading portion” always being encountered before a “trailing portion.” 
         [0056]     The term “leading edge” as used herein with respect to a waste area refers to the line along the farthest upstream boundary of the leading edge portion of such waste area.  
         [0057]     The term “width” as used herein with respect to a waste area refers to a dimensional measurement taken across the waste area in a direction substantially perpendicular to the weeding direction.  
         [0058]     The term “chord line” as used herein refers to the line along which separation of a waste area from the backing layer takes place, with the length of the chord line being equal to the length of the continuous portion of the waste area being separated from the backing layer. Thus, if the weeding process is occurring across a wide sheet of laminate, it is possible that there could be more than one “chord line” defined locally along the line of separation.  
         [0059]     The term “force ratio” as used herein refers to the ratio of “adhering forces” to “pulling forces” on a portion of face layer. With respect to portions of a waste area which are to be separated from the backing layer, “adhering forces” include both (1) the holding force of the adhesive layer (between the face layer and the backing layer of the laminate material) and (2) any additional forces from the surrounding face layer (i.e., the force exerted on the portion of waste area by the surrounding product area from incomplete slitting of the face layer and/or the adhesive layer and/or from rejoining of portions of the adhesive layer on either side of the slit) which are holding the portion of the waste area in place, and “pulling forces” are adhesive forces between the waste areas and the carrier surface from the adhesive applied the waste areas. With respect to portions of a product area (not intended to be separated from backing layer), “adhering forces” are the force applied by the adhesive layer between the face layer and the backing layer of the laminate material, and “pulling forces” include both (1) the force exerted on the portion of the product area by the surrounding waste area being removed from around the portion of the product area (i.e., similar to the forces from surrounding waste area described above) and (2) any small forces which might occur from the contact of the carrier surface with the portion of the product area. (These force considerations are of course qualitative in nature and imply consistent bases of determination, whatever they may be—e.g., taking into consideration both normal forces and shear forces.)  
         [0060]     The term “delicate leading edge portion” as used herein with respect to a product area refers to a portion of the product area for which the force ratio is approximately one or less than one and which has a dimension along the weeding direction. Thus, delicate leading edge portions of product areas are susceptible to unwanted separation from the backing layer unless the force ratio is raised. Examples of delicate leading edge portions of product areas include pointed leading edge portions such as the points of a star or small shapes such as letters.  
         [0061]     The term “force-modifying slit” as used herein refers to cuts made in the trailing edge portion of a waste area adjacent to and surrounding a delicate leading edge portion of a product area to change the force ratio of the portion of the product area.  
         [0062]     The term “starter tab” as used herein refers to small areas of waste area added to leading edge portions of waste area and extending in the upstream direction from the leading edge portion in order to change the force ratio of the leading edge portion of waste area, thereby enabling initiation of the separation of the waste area from the backing layer.  
         [0063]     The term “particularly delicate product area” as used herein refers to entire product areas which are characterized by a low force ratio.  
         [0064]     The term “temporary product area” as used herein refers to a small area of waste area which is not separated from around particularly delicate product areas and which are separated from the backing layer by hand after completion of the automatic weeding process. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0065]     The drawings illustrate preferred embodiments which include the above-noted characteristics and features of the invention. The invention will be readily understood from the descriptions and drawings. In the drawings:  
         [0066]      FIG. 1  is a highly schematic, fragmentary perspective view (not to scale) of an apparatus in accordance with this invention. In particular, the thicknesses of the laminate layers and carrier web are greatly exaggerated to help illustrate the principles of this invention.  
         [0067]      FIG. 2  is a schematic, fragmentary perspective view of a laminate, including product areas and a surrounding waste area, such laminate again being illustrated out of scale as to thickness.  
         [0068]      FIG. 3  is a schematic, side elevation of an adhesive applicator adjacent to a laminate (to be weeded) on a support surface. The laminate is again illustrated out of scale as to thickness.  
         [0069]      FIG. 4  is a schematic, fragmentary perspective view of  FIG. 3 . The laminate is again illustrated out of scale as to thickness.  
         [0070]      FIG. 5  is a schematic side elevation of an endless carrier web and its associated separator edge and waste-area stripper. The laminate and carrier web are again illustrated out of scale as to thickness.  
         [0071]      FIG. 6  is a schematic fragmentary plan view of the arrangement of parts of a sensing and adhesive applicator apparatus of a preferred embodiment of this invention, such sensing and applicator apparatus having multiple sensors and multiple jet applicators for adhesive.  
         [0072]      FIG. 7  is a schematic side elevation representing an alternative applicator apparatus for application of adhesive on intended portions of waste areas to be removed. Once again, the laminate is illustrated far out of scale as to thickness.  
         [0073]      FIG. 8   a  is a top view of a portion of a sheet of laminate illustrating a waste area leading edge portion which is perpendicular to the weeding direction.  
         [0074]      FIG. 8   b  is a top view of a portion of a sheet of laminate illustrating a preferred force-modifying feature included in a preferred shape of a waste area leading edge portion.  
         [0075]      FIG. 9  is a top view of a portion of a sheet of laminate illustrating a force-modifying feature placed near a trailing edge portion of a waste area adjacent to a leading edge of a delicate feature of a product area.  
         [0076]      FIGS. 10   a  and  10   b  are enlarged portions of  FIG. 9 .  
         [0077]      FIG. 11  is a top view of a particularly delicate product area surrounded by a temporary product area.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0078]     Before describing sheet-weeding apparatus  10  and its various elements, which should be understood to be represented in highly schematic fashion, it will be helpful to describe the laminate upon which sheet-weeding apparatus  10  is operating and to illustrate some of the terms used to describe the sheet-weeder operation. Referring to  FIG. 2 , the laminate  50  a discrete sheet made up of multiple layers, including face layer  52 , adhesive layer  54 , and backing layer  56 .  FIGS. 1 and 3 - 7  also include illustrations of laminate sheet or sheets  50  with face layer  52 , adhesive layer  54 , and backing layer  56 .  
         [0079]     Referring again to  FIG. 2 , face layer  52  has been slit (severed), with the slit lines isolating product areas  58  from waste areas  60 . Product areas  58  are shown in simple form; in many cases, the shapes of product areas may be very complex or intricate, and may have islands of waste areas within them. When waste areas  60  are weeded from laminate sheet  50 , products areas  58  remain on backing layer  56  for their eventual intended use.  
         [0080]      FIG. 2  further illustrates the leading and trailing edges of both product areas  58  and waste areas  60 . If motion of laminate sheet  50  is assumed to be left to right as indicated in  FIG. 2 , then the location of a leading edge  68  of waste area  60  is as indicated. In similar fashion, a trailing edge  70  of a product area  58 , a leading edge  64  of a product area  58 , and a trailing edge  66  of a waste area  60  are indicated in  FIG. 2 .  
         [0081]      FIG. 2  further illustrates discrete locations  62  of adhesive  72  applied to waste areas  60  of face layer  52 . Adhesive  72  can be one of various quick-drying adhesives which are known in the art. Acceptable choices would be known to those skilled in the art and who are made aware of this invention. One group of adhesives which are useful are permanent waterborne acrylic pressure-sensitive adhesives available from ICI Americas Inc., New York, N.Y.  
         [0082]     Referring to  FIGS. 3 and 4 , adhesive applicator  76  is positioned over discrete locations  62  on face layer  52  and applies adhesive  72  to discrete locations  62 . As shown in  FIGS. 3 and 4 , adhesive applicator  76  does not make contact with face layer  52  of laminate sheet  50 , but applies adhesive  72  by rapidly and accurately shooting small quantities of adhesive  72  in the form of droplets or spray  74 . Applicators suitable for use as adhesive applicator  76 , such as a jet or sprayer, are known in the art.  FIG. 4  further illustrates a work surface  12  adjacent to applicator  76  for receiving laminate sheets  50 .  FIGS. 6 and 7 , described further below, illustrate alternative devices for adhesive application.  
         [0083]     Referring now to  FIG. 1 , which illustrates a much larger portion of inventive sheet-weeding apparatus  10 , the embodiment shown is of the type which incorporates a carrier-surface member in the form of a carrier web  14  and in which carrier web  14  is moving in apparatus  10  in a direction along its length.  
         [0084]     In  FIG. 1 , laminate sheets  50  and carrier web  14  are moving from right to left through apparatus  10 . As a laminate sheet  50  moves from right to left, laminate sheet  50  is at first received and supported by support by work surface  12 . Adhesive applicator  76  is mounted adjacent to work surface  12  on an actuator apparatus  36 . Actuator apparatus  36  includes an actuator frame  38  and an actuator bar  40 , and is configured and arranged such that adhesive applicator  76  can be moved back and forth along actuator bar  40  and actuator bar  40  can be moved back and forth along actuator frame  38 , all under computer control as referred to below. In this way, any point on face layer  52  is available to receive adhesive  72 . It should be noted that a plurality of applicators can be associated with one or more actuator apparatuses.  
         [0085]     Still referring to  FIG. 1 , a sensor  78  is also adjacent to work surface  12  and is mounted such that it can be moved back and forth along actuator bar  40  along with adhesive applicator  76 . Sensor  78  is responsive to registration marks  44 . Sensor  78 , actuator apparatus  36 , and applicator  76  are connected to controller  46  through controller cable  48 . Controller  46  is a computer programmed with information on product areas  58  and waste areas  60  such that the position of product areas  58  and waste areas  60  on work surface  12  enable actuator  36  to respond to controller  46  to move applicator  76  to the desired locations on face layer  52  and apply the precise amount of adhesive  72  to face layer  52 .  
         [0086]     Carrier web  14  is unrolled from a carrier web supply roll  16  and temporarily laminated with laminate sheet  50  by passing through a laminator, which includes a face layer laminator roller  18  and a backing layer laminator roller  20 . The temporary lamination formed by laminator rollers  18  and  20  is held together by applied adhesive  72 , and is referred to as a carrier lamination  24 . Carrier lamination  24  is in tension as carrier lamination  24  is received by a delaminator  26 , which includes a separator edge  28  and a retaining bar  30 . Separator edge  28  has a tightly-rounded leading edge  32  which is shaped such that waste areas  60  are lifted off backing layer  56  as carrier lamination  24  passes over leading edge  32 . Retaining bar  30  of delaminator  26  is positioned such that product areas  58  are prevented from being lifted up as carrier lamination  24  passes over separator edge  32 .  
         [0087]     After passing through delaminator  26 , waste areas  60  remain adhered to carrier web  14  by adhesive  72 , and product areas  58  remain on backing layer  56  for later use as intended. The weeded laminates are collected in a pile, ready for use.  
         [0088]     Carrier web  14 , with waste areas  60  remaining on it, is taken up by a carrier web take-up roller  34 . When carrier web take-up roller  34  is full, it can be discarded and replaced with an empty roller. Carrier web  14  is preferably low-cost newsprint or the like.  
         [0089]     As is by now apparent,  FIG. 1  illustrates two laminate sheets  50 , the first one (to the left in  FIG. 1 ) undergoing separation after adhering to carrier web  14  and the second one (to the right in  FIG. 1 ) having adhesive applied to its waste areas. It should be noted that, instead of being in the form of discrete sheets, the laminate could be in the form of a continuous laminate web. In such case, after weeding the weeded web, with its product areas ready for use, would itself be wound onto a take-up roller.  
         [0090]     Referring again now to the second (the rightmost) laminate sheet shown in  FIG. 1 , such laminate sheet (like that before it) has a waste area along its leading edge and illustrates adhesive having been applied to a leading edge portion of such waste area. It should also be noted that, with respect to product area  58  as seen on the second laminate sheet in  FIG. 1 , adhesive is being applied all around the perimeter of product area  50 . With respect to adhesive application at portions of waste areas around product areas,  FIG. 6 , discussed more below, serves to illustrate the application of adhesive only at leading portions of waste areas around product areas.  
         [0091]      FIG. 5  illustrates schematically a portion of another sheet-weeder apparatus  90  incorporating a carrier-surface member  80  which is in the form of an endless carrier web. Apparatus  90  also includes a separator edge  28  and a stripper  82 . In similar fashion to apparatus  10  of  FIG. 1 , laminate sheet  50  and endless carrier web  80  move between a face layer laminator roller  18  and a backing layer laminator roller  20  to form a temporary carrier lamination  24 .  
         [0092]     Also in similar fashion to apparatus  10  of  FIG. 1 , separator edge  28  of apparatus  90  facilitates the lifting of waste areas  60  from backing layer  56 , leaving product areas  58  on backing layer  56  for later use as intended, while waste areas  60  remain adhered to endless carrier web  80 . Unlike apparatus  10  of  FIG. 1 , however, waste areas  60  which remain on endless carrier web  80  are removed from endless carrier web  80  by stripper  82 , immediately freeing that portion of endless carrier web  80  for reuse. Stripper  82  incorporates a knife edge  86  which scrapes waste areas  60  from endless carrier web  80  and discards them into a waste bin  84 .  
         [0093]     Alternative strippers can include apparatus which applies heat (or removes heat, i.e., makes cold) in order to soften (or harden) the adhesive and release, or at least facilitate release of, waste areas from the endless carrier web or other carrier-surface member. Depending on the particular location along the endless carrier web (or other carrier-surface member) and depending on the type of adhesive used, differing temperature levels may be used to accomplish the adhering or releasing of laminate layers. Alternatives for the waste bin can include, e.g., a take-up roller to collect continuous waste areas removed from the endless carrier web by the stripper or a chopper and a conveyor to discard large amounts of waste material.  
         [0094]     Precise application of adhesive to waste areas for sheet-weeding purposes depends on accurate information about the locations of product areas and waste areas. There are numerous ways in which such locations can be determined. Highly preferred ways involve the sensing of registration marks  44 . For example, sensors can be in a line as is common in a computer scanner and either be fixed to a frame or free to move. Another alternative is that sensor  78  and applicator  76  can be moved independently to speed up operation of apparatus  10 .  
         [0095]     Referring now to the actuator apparatus with which one or more adhesive applicators are associated (for its/their control), the actuator apparatus can be designed to move the applicator(s) (and/or sensors) along three axes (rather just the two illustrated in  FIG. 1 ) to give added flexibility and capability to the sheet-weeding apparatus.  
         [0096]     Referring to the pattern of adhesive application, adhesive may be applied in discrete locations as illustrated, or can be applied in line segments, continuous lines, or even in wide areas as appropriate to the particular sheet-weeding application. This can include the entire surface of the waste area or areas. One preferred pattern, as illustrated by the rightmost product area of  FIG. 2 , involves application of adhesive on waste areas just beyond all of the edges of the product areas. Another pattern can be continuous lines along the length of the laminate—e.g., to remove waste areas along the edges of the laminate, such as in the production of pressure-sensitive labels.  
         [0097]      FIG. 6  illustrates schematically a highly preferred location sensing and adhesive-application apparatus  92  having several sensing and adhesive-applicator units  94  arranged side by side in a line across laminate. Sensing/applicator units  94  need not move in order to sense the locations of registration marks  44  or to apply adhesive in the proper locations on the two laminate sheets  50  that are shown in  FIG. 6 . Instead, based on their sensing and the rate of movement of laminate sheets  50 , the adhesive applicators of sensing/applicator units  94  apply adhesive  72  at the proper time to be applied to discrete locations  62 , which are the locations programmed to be appropriate to facilitate the later separating step.  FIG. 6  also serves to illustrate the preferred application of adhesive on various selected leading edge portions  68  of the waste areas  60  of two discrete laminate sheets  50 , as the laminate sheets pass sensing and adhesive-application apparatus  92 .  
         [0098]      FIG. 7  illustrates another alternative adhesive-application apparatus  95 , in this case an applicator which applies adhesive by direct contact with face layer  52  of laminate sheet  50 . Adhesive application apparatus  95  applies adhesive  96  by means of an applicator roller  97  that has contact members  98  positioned to engage face layer  52  at the intended portions of its waste areas. Contact members  98  of applicator roller  97  receive adhesive  96  via transfer rollers  99 , and deposit such adhesive upon contact with face layer  52 . A variety of other adhesive applicator devices can be used in the apparatus of this invention.  
         [0099]      FIGS. 8   a  and  8   b  illustrate an additional aspect of the inventive method wherein the leading edge of a waste area  60  is configured to facilitate more efficient and reliable removal of waste area  60  from the backing layer of the laminate. Waste area  60  surrounds product areas  58 . In  FIG. 8   a , a leading edge portion  110  of waste area  60  is substantially perpendicular to the weeding direction. As the separation process progresses along laminate sheet  50 , the line of separation (not shown) reaches the leading edge  111  of leading edge portion  110 , and a pulling force is applied to leading edge portion  110  through adhesive  72  (shown as deposited at a series of discrete locations across leading edge portion  110 ). Since leading edge  111  is perpendicular to the weeding direction, the total force required to cause separation suddenly increases as the line of separation reaches leading edge portion  110 . Depending on a number of variables such as the nature of the various material surfaces and the adhesive strengths of adhesive  72  and the adhesive layer of the laminate, the force ratio may be too high, thus preventing leading edge portion  110  from separating cleanly from the backing layer.  
         [0100]      FIG. 8   b  illustrates a preferred embodiment of the inventive method which lowers the force ratio, thereby enabling efficient and reliable separation of waste area from backing layer. The leading edge  113  of a leading edge portion  112  is given a slightly convex shape, thereby dividing leading edge  113  into a lead part  114  and two trailing lateral parts  116   a  and  116   b . (The approximate width of parts  114 ,  116   a , and  116   b  are indicated in  FIG. 8   b  by the brackets drawn upstream of leading edge  113 .) As the line of separation progresses along sheet  50 , the line of separation reaches lead part  114  prior to reaching trailing lateral parts  116   a  and  116   b . The length of the chord line across leading edge portion  112  gradually increases in length as the line of separation moves along sheet  50  in the weeding direction, thereby lowering the force ratio at the initiation of separation of waste area  60  and gradually raising the total force required to separate leading edge portion  112  from backing layer as the separation progresses.  
         [0101]      FIG. 8   b  also illustrates a highly preferred embodiment of leading edge portion  112 . Starter tabs  100  (three shown), extending in a substantially upstream direction from lead part  114 , are added to leading edge portion  112  along lead part  114  of leading edge  113 . Starter tabs  100  lower the force required to initiate separation as the line of separation encounters leading edge portion  113 , thereby further increasing the efficiency and reliability of the separation process.  
         [0102]      FIG. 9  illustrates another highly preferred embodiment of the inventive method. Sheet  50  is shown with waste area  60  and product areas  58   a ,  58   b ,  58   c , and  58   d , with each such product area having delicate leading edge portions  59   a ,  59   b ,  59   c , and  59   d  respectively. Force-modifying slits  102   a ,  102   b ,  102   c , and  102   d  surround delicate leading edge portions  59   a ,  59   b ,  59   c , and  59   d  respectively.  FIGS. 10   a  and  10   b  provide enlarged views of product areas  58   a  and  58   d  respectively. Trailing edge portions  120  and  122  are adjacent to delicate leading edge portions  59   a  and  59   d  respectively, with trailing edge portions  120  and  122  having force-modifying slits  102   a  and  102   d  respectively. (Trailing edge portions  120  and  122  are each shown with multiple indicators to illustrate that trailing edge portions  120  and  122  are areas of waste area which surround delicate leading edge portions  59   a  and  59   d  respectively.) In  FIG. 10   a , force-modifying slit  102   a  is positioned such that the end points  104   a  and  104   b  of slit  102   a  are on opposite sides of delicate leading edge portion  59   a . As the line of separation progresses along sheet  50  in the weeding direction reaching the upstream portion of slit  102   a  at trailing edge portion  120 , slit  102   a  allows trailing edge portion  120  to temporarily remain on the backing layer until the line of separation progresses to end points  104   a  and  104   b . At this time, the force ratio for delicate leading edge portion  59   a  is high enough to cause separation of trailing edge portion  120  from the backing layer without causing delicate leading edge portion  59   a  to be separated from the backing layer.  
         [0103]      FIG. 10   b  illustrates delicate leading edge portion  59   d , having an even sharper point than delicate leading portion  59   a . In similar fashion to events described in  FIG. 10   a , separation of delicate leading edge portion  59   d  is prevented. End points  106   a  and  106   b  of slit  102   d  are comparatively farther downstream than endpoints  104   a  and  104   b , thus accommodating the increased sharpness of delicate leading edge portion  59   d.    
         [0104]      FIG. 11  illustrates another embodiment of the inventive method in which a temporary product area surrounds a particularly delicate product area. Sheet  50  is shown with waste area  60  surrounding a temporary product area  132  which surrounds a particularly delicate product area  130 . In situations for which the force ratio for an entire product area is near or less than one, such as is illustrated by particularly delicate product area  130 , temporary product area  132  is not separated from the backing layer by the automatic weeding process but is removed by manual weeding after the completion of the automatic weeding process. While the principles of this invention have been described in connection with specific embodiments, it should be understood clearly that these descriptions are made only by way of example and are not intended to limit the scope of the invention.

Technology Classification (CPC): 8