Abstract:
A shelf-front label holder is provided with a specifically improved form of auxiliary sign clip along its upper front edge. The label holder is formed of a relatively rigid plastic material, and the sign clip includes a downwardly extending portion overlying the upper front margin of the label holder to accommodate upward insertion of special sign tags. A thin, flexible tongue-like retaining element extends across a lower portion of the sign clip and is adapted to be easily deflected by upward insertion of a paper sign but thereafter lightly grips the sign to hold it in place. A new process is also disclosed for the continuous extrusion of the new label holder product, enabling the continuous co-extrusion of the soft, flexible tongue-like retaining element together with the main section of the label holder.

Description:
RELATED CASES 
     This application is related to the application Ser. No. 09/587,695, filed Jun. 5, 2000 by Thomas O. Nagel, now U.S. Pat. No. 6,266,906, granted Jul. 31, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     Mass merchandisers such as grocery chains, drug chains, discount department stores, and the like make extensive use of merchandise display shelving in which shelves are provided along their front edges with ticket moldings or data strips for displaying pricing and other information related to the displayed merchandise. In many modern installations, plastic strips are used in preference to extruded metal ticket moldings. In some instances, the plastic strips are constructed to be mounted within existing metal ticket moldings. In other cases, the strips are mounted directly to the front edge of the shelving. 
     One commonly used form of plastic data strip is comprised of a continuous extruded section of plastic material provided with a clear plastic front panel joined along its bottom edge to a back panel structure. The back panel structure may comprise a single panel, which is secured to the front edge of the shelving, or it may include an additional panel configured to be snapped into the front of a conventional metal ticket molding, for example. In either case, the clear front panel and the back panel structure form a continuous, upwardly opening label-receiving pocket for receiving pricing and information labels and the like. 
     It is a customary practice of stores of the type mentioned above to emphasize certain items in their displays, from time to time, such as new items, items that are featured on special sale, etc. Where conventional metal ticket moldings are employed, such special tags frequently are installed using plastic clips, which are inserted into the ticket molding, and provide a prominent display for the special tag. Where plastic data strips are utilized for the main pricing information, the special tags frequently are printed on thin, heat-bent plastic elements designed to be installed behind the clear front panel of the data strip. The special information can be printed on the plastic element, or on a paper tag which is enveloped within the special plastic element. In any case, these special plastic clips or elements involve undesirable added expense. While in some cases, they may be reused, they usually are thrown away after one or two uses. Moreover, the handling and storage of such reusable items is both an expense and an annoyance. 
     In the related case referred to above, a plastic data strip is provided along its upper front edge with a continuous, downwardly projecting overlay panel, joined integrally with the upper edge of the front panel, which forms a downwardly opening tag-receiving pocket along the uppermost edge margin of the front panel. The overlay panel is configured to converge with the surface of the front panel, to form a narrow throat, and thereafter to project forwardly to form a downwardly divergent entry. The overlay panel enables a thin, inexpensive and disposable printed paper tag to be inserted anywhere along the entire length of the data strip, by inserting an upper edge portion of the paper tag underneath the overlay panel. When the special tag has served its purpose, it can simply be removed and discarded. The device of the related application advantageously is formed with a narrow bead of co-extruded soft plastic material along the narrow throat portion of the overlay panel to improve the gripping action of the tag-receiving pocket on a light paper tag inserted therein, without unduly resisting insertion of the tag during installation. 
     SUMMARY OF THE INVENTION 
     Because the special tag to be inserted under the overlay panel typically is thin and flimsy, it is important that the overlay accommodate easy upward insertion of the tag while at the same time providing reliable retention of the tag by gripping its upper edge margin. These are somewhat mutually inconsistent requirements, in that the optimum arrangement requires a somewhat easier insertion of the tag than its removal. To accommodate this optimum performance desire, the display strip of the present invention incorporates an overlay panel construction in which the tag-holding clip includes a thin, highly flexible co-extruded tongue-like element of soft material which flexes easily to allow upward entry of the tag. At the same time, this flexible element effectively resists downward movement of the tag, unless intentional force is applied. In this respect, the soft, flexible tongue-like element advantageously is oriented to be inclined slightly upward, such that it is easily flexed upwardly for insertion of a thin paper tag. Downward movement of the tag, however, is resisted more strongly, as the flexible tongue-like element is displaced slightly downward, to extend more directly across the throat of the tag-holding clip and thus exert more retention force on the tag. 
     While the principal plastic data strip is extruded of a relatively hard plastic material, such as rigid polyvinyl chloride (PVC), the co-extruded tongue-like element is formed of a considerably softer material, typically a compatible soft PVC material. While co-extrusion of such materials, as a general proposition, is widely practiced, the display strip of the present invention presents a particularly difficult problem in the manufacture, because of the relatively tiny dimensions of the co-extruded tongue-like element. 
     In accordance with the invention, the co-extrusion process is in effect carried out in two stages. The primary strip, formed of so-called rigid PVC or other plastic material, is formed by extruding molten plastic material through an extrusion die of appropriate configuration, in a generally known manner, emerging from the extrusion die without the intended co-extruded tongue-like element. A second and separate extrusion die is placed on or immediately adjacent to the front face of the primary die and is positioned to be partly enveloped by the upper margin of the front panel of the display strip, on one side, and by the short clip-forming overlay panel, on the other side. Significantly, as the primary display strip merges from its extrusion nozzle, the tag-holding clip portion thereof has a substantially wide-open configuration, allowing an upper portion of the second extrusion nozzle to be easily received within the downwardly opening recess formed along the upper edge of the display strip. At this juncture, the plastic material forming the principal part of the display strip is still in the form of a highly viscous, semi-liquid material. Immediately as this semi-liquid material emerges from its extrusion nozzle, it is joined by the flow of softer plastic co-extrusion material emerging from the second nozzle, so that the two materials are joined in a co-extrusion in a manner that enables the small, delicate tongue-like element to retain its desired shape and effectively prevents from being overwhelmed and deformed by the heavier section of the primary extrusion. Immediately following the second extrusion step, the co-extruded shape separates from the second extrusion die and is drawn under slight tension into a so-called calibrating die, which reshapes the strip into its desired, final cross-sectional configuration. While the material is traveling to and through the calibrating die, it is still extremely soft and pliable, and easily conforms to the desired final shape, including a closing of the tag-holding clip portion to its final configuration, with a narrow entrance throat closed by the co-extruded soft plastic tongue-like element. Typically, as the extruded section emerges from the downstream side of the calibrating die, it is immediately immersed in a cooling liquid to harden the plastic and permanently fix the final shape of the strip. The finished strip is then cut into suitable lengths, (typically four feet) for installation on standard store shelving. 
     The process of the invention enables truly unique and advantageous label display of product to be produced on a controlled, high production basis. 
     For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiments of the invention, and to the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a typical form of label display strip incorporating features of the invention and produced in accordance with the process of the invention. 
     FIG. 2 is a front elevational view of a dual extrusion die arrangement according to the invention for a two-step co-extrusion of a label display strip with integral tag-holding clip. 
     FIG. 3 is an enlarged, fragmentary illustration of the encircled area of FIG. 2, showing details of the second-stage extrusion die. 
     FIG. 4 is a schematic illustration of a two-step co-extrusion process according to the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, a typical and advantageous form of label display strip according to the invention is illustrated in FIG.  1 . Specific dimensions are not a part of the invention, although dimensions may be referred to herein for convenience and to indicate typical practices in the field. Label display strip  10  of FIG. 1 includes a front panel  11 , formed of clear plastic material, and a first back panel  12 , also formed of plastic material, but not necessarily clear. The front and back panels  11 - 12  are integrally joined at  13 , along their bottom edges, forming an upwardly open pocket for the reception of information and pricing labels (not shown). Commonly, the structure of the lower edge area of the label-holding strip includes a short forward projection  14 , which provides stress relief, and also functions as a guide flange for a barcode reader, for example. 
     In the illustrated form of the invention, a second back panel  15  is provided, integrally attached to the top edge portion  16  of the first back panel  12  and typically having a portion  17  extending above the upper edge of the back panel  12 . Second back panel  15 , where employed, provides a means for mounting the label display strip within the channel of a pre-existing metal price tag molding, frequently provided at the front edges of merchandise shelving. Where the shelving does not have a previous installation of the metal price tag molding, it may be expedient to eliminate the second back panel  15  and secure the label display strip directly to the front edge of a shelf by adhesive bonding of the back panel  12 , for example. These are well-known alternatives in the art, and do not form part of the present invention. 
     In the illustrated and preferred form of the invention, the front panel  11  and back panels  12 , 15  preferably, are formed of a rigid polyvinyl chloride. A label display strip of around 1.25 inches in height may typically have a panel thickness of around 0.016 inch. 
     As indicated in FIG. 1, the upper margin  18  of the front panel is joined with a downwardly extending overlay panel  19 , by means of a connecting top section  20 . The overlay panel  19  extends downward and somewhat inward, and preferably terminates in an outturned guide flange  21 . The elements  18 - 21  are advantageously formed of the same rigid PVC material of which the main panels  11 ,  12  and  15  are formed. 
     Extending generally rearwardly from the overlay panel  19  is a tongue-like retaining element  22 , which is formed of a soft, flexible polyvinyl chloride composition and is co-extruded with the overlay panel  19  in a manner to be described hereinafter. Desirably, the retaining element  22  may be of slightly narrower cross-section at its root  23 , where it joins with the overlay panel, to provide for easy flexibility of the element  22 . 
     As is evident in FIG. 1, the tongue-like retaining element  22  preferably is disposed at an upwardly inclined angle, and its distal edge  24  lightly touches the front surface of the upper panel margin  18 . Preferably, the front panel  11  is formed with a small, forwardly projecting rib  25 , which extends along the length of the label display strip below the free edge  24  of the tongue-like retaining element  22 . 
     In typical use of the label display strip of FIG. 1, a normal pricing and information label is inserted therein by displacing the upper portion of the front panel  11  forwardly relative to the back panel  12 , opening a pocket between those two panels. The label (not shown) is inserted downward into the pocket  26  between the panels and is retained therein when the front panel is released. The label is readily viewable through the clear, transparent front panel  11  of the display strip. 
     For calling special attention to selected items, a special tag  27 , which may be printed on ordinary paper, for example, is inserted upwardly into the tag-holding clip formed by the elements  18 - 22 . When the tag  27  is inserted upwardly into the clip, the upper edge of the tag engages the flexible tongue-like element  22  and displaces that element upwardly a sufficient distance to allow the upper margin of the tag to slide by. The upwardly inclined orientation of the tongue-like element  22  facilitates the insertion of tag  27 , as will be appreciated. The inherent resilience of the retaining element  22  causes the upper margin of the tag  27  to be gripped between the front surface of the panel margin  18  and the free end  24  of the retaining element  22  just above the rib  25 . Slight downward forces on the tag  27  will simply cause the retaining element  22  to exert its grip more firmly. Because of the upwardly inclined orientation, the retaining element tends to be displaced downwardly by downward forces on the tag  27 . This causes the retaining element to increase its gripping force. The underlying rib  25  tends to limit the downward displacement of the retaining element as will be understood. While the tag  27  is thus reliably held in place in the tag-holding clip, nevertheless, it may be removed by intentional force applied downwardly to the tag, when its removal is desired. 
     Desirably, to impart a desired degree of flexibility, the tongue-like retaining element  22  has a projecting length substantially greater than its thickness. By way of example only, its projecting length may be approximately 0.045 inch, whereas its thickness may be approximately one third of its length. The throat area  28 , defined between the front surface of the front panel  11 , and the lower back edge area  28 , defined between the front surface of the front panel  11  and the lower back edge area of the overlay panel, can be comfortably large to facilitate insertion of the special tag  27 . For example, a throat width of about 0.03 is easily accommodated. The tag is thus easily inserted into the clip, meeting no resistance until it engages the flexible tongue-like element  22 . 
     Production of the described device pursuant to procedures of the invention involves a special two-stage co-extrusion procedure, in which the main body of the data strip is initially extruded from a primary extrusion nozzle and, immediately upon its emergence from the primary nozzle, and while the material of the strip body remains in semi-molten condition, the soft tongue-like element is co-extruded onto an inner surface of the overlay panel  19 . With reference now to FIGS. 2-4, the reference numeral  30  designates generally the front face of a primary extrusion nozzle forming part of a conventional extrusion machine indicated generally by the reference numeral  31  in FIG.  4 . The extrusion nozzle  30  is formed with an opening  32  having a cross sectional configuration generally related to that of the data strip  10  of FIG.  1 . The configuration of the nozzle opening  32  is, however, laterally expanded in relation to the final configuration of the panels of the data strip and of somewhat larger dimensions. Thus, as, the strip emerges from the extruder nozzle, it has the same, expanded cross sectional configuration as that of the nozzle opening  32 . 
     Pursuant to the invention, the overlay panel  19  emerging from the primary extrusion nozzle is expanded away from the upper margin  18  of the back panel  12 , as shown particularly in FIG.  3 . This forms a wide, downwardly opening pocket between the panels  18 ,  19 . 
     A secondary extrusion nozzle  33  is positioned immediately adjacent to the front face  34  of the primary extrusion nozzle, and preferably is fastened directly to the nozzle front face, by bolts  35 . The upper extremity  36  of the secondary extrusion nozzle is received within the downwardly opening pocket defined by the overlay panel  19  and the upper panel margin  18 . Desirably, the nozzle extremity  36  has cross sectional contours corresponding closely to the internal cross sectional configuration defined by the strip elements  18 - 20 , as is evident in FIG.  3 . 
     The secondary extrusion nozzle  33  is provided with internal supply passages  37 ,  38  communicating with the outer end of a discharge slot  39 . The slot  39  is open at the front, and conveniently also at the back where the secondary nozzle is bolted directly to the front of the primary nozzle. The cross sectional configuration of the discharge slot  39 , as viewed from in front of the primary extrusion nozzle  30 , corresponds with the cross sectional configuration of the tongue-like retaining element  22 . The discharge slot  39  is also open at one side of the nozzle extremity  36  facing a lower portion of the overlay panel  19 . 
     The passages  37 ,  38  of the secondary extrusion nozzle  33  are supplied with the softer co-extrusion material (e.g., soft PVC) to form the tongue-like element  22 . As is the material forming the more rigid portions of the data strip emerge from the primary nozzle  30 , and while such material remains in a semi-molten state, it is immediately contacted by the co-extrusion material issuing from the discharge slot  39  of the secondary extrusion nozzle. The semi-molten materials bond instantly, joining the tongue-like retaining element  22  to the inner surface of the overlay panel  19  in the manner desired. 
     As reflected in FIG. 4, the combined extruded materials travel forwardly from the extrusion dies  30 ,  33  into a calibration die  40 . The calibration die  40 , in itself known and not a part of the present invention, conforms the extruded strip to its final size and configuration by closing up the various expanded panels and sections of the strip, and preferably also reducing the overall dimensions of the final product. 
     Typically, the strip material  41  exiting from the calibration nozzle  40 , is maintained under linear tension, by any suitable means (not shown) located downstream of the illustration of FIG.  4 . Thus, the still-soft material in the region  42 , between the extrusion nozzles  30 ,  33  and the calibration die  40 , is under controlled tension, causing the material to be elongated and somewhat reduced in size, and then configured to its final cross sectional shape in the calibration die  40 . 
     In the illustrated arrangement, the calibration die discharges the material  41  into a cooling bath  43  to completely solidify and harden the extrusion materials. As the extruded strip continues downstream, it typically is cut into desired lengths, for example, four feet, for attachment to standard merchandise display shelving. 
     The two-stage extrusion technique of the invention enables the co-extrusion of a relatively elongated tongue-like retaining element, which is functionally superior to merely co-extruding a soft bead or surface area on the overlay panel  19 . The soft flexible tongue-like element is easily displaced by upward pressure on a tag element  27 , yet provides highly effective retention of the tag in its installed position. 
     By co-extruding the soft tongue cross section with the primary strip material immediately upon its emergence from the primary extrusion die, it is possible to retain the integrity and cross sectional configuration of the delicate tongue-like element. The secondary extrusion is performed while the clip area  18 - 20  of the strip is in an open or expanded configuration, accommodating the presence of the secondary nozzle to extrude the tongue-like element. Later, as the strip passes through the calibrating die, the clip area of the strip is closed to the configuration of FIG. 1, with the outer end extremity  24  of the tongue-like element lightly contacting the upper panel margin  18 . 
     It should be understood, of course, that the specific forms of the invention herein illustrated and described are intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.