Abstract:
An RFID label is bonded to the surface of a plastic container. The label includes a web of label stock having an antenna and an RFID chip on the reverse side of the label. The antenna and the chip are between the label and the container. The obverse side of the label is visible on the exterior of the container and includes printed material such as a barcode. A protective patch may overlie the RFID chip to protect the RFID chip from the molten polymer during the molding process.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates generally to radio frequency identification (“RFID”) devices, and more particularly to an RFID label for attachment to a waste container.  
         [0002]     RFID devices are well known for the advantages they provide in information storage. An RFID device can be attached to a variety of different products for storing unique information about that product. These devices generally include a scannable circuit board, or “RFID chip”, that may be programmed with unique identification information, and an antenna for transmitting the information to a reader. The devices do not need batteries, as they are powered by an electromagnetic field generated by the reader. The ability to write information to the chip from the reader allows the stored information to be updated only in an authorized manner.  
         [0003]     RFID devices are useful in a variety of industries. For example, in the waste container industry, an RFID device may be attached to a waste container for storing information unique to that container, such as an identification number, and the time and date of manufacture. The stored information can be scanned by a reader located on the waste truck.  
         [0004]     An example of an RFID device attached to a waste container is shown in U.S. Pat. No. 6,206,282. The RFID chip is embedded within the sidewall of a waste container during thermoforming of the container. Unfortunately, a number of difficulties arise in this arrangement. First, the molding process must be altered to accommodate for the insertion of a chip into the molten polymer during the molding process. This includes the insertion of special pins to hold the chip in place until the plastic has completely cured. Second, the area surrounding the chip must be cooled to avoid damaging the sensitive chip. Third, it may be difficult to read and transmit information to the chip because it is entirely embedded in plastic.  
       SUMMARY OF THE INVENTION  
       [0005]     The aforementioned problems are overcome by the present invention, wherein an RFID chip and antenna are attached to a label that is attached to the surface of a plastic waste container during molding of the container.  
         [0006]     In a first embodiment, the present invention includes a web of label stock having a first surface and a second surface opposite the first surface. An antenna is printed on the second surface with conductive ink, and an RFID chip is attached to the antenna, for example with a conductive adhesive. The second surface of the label is molded to the surface of a container during molding of the container. Consequently, the RFID chip is between the label and the surface of the container, and the first surface is visible.  
         [0007]     In a further refinement of the first embodiment, a barcode is printed on the first surface of the label stock, possibly with additional printed material such as a corporate logo. The barcode may correspond to the information stored on the RFID chip. One or both of the surfaces of the label may be coated with a protective UV coating. Consequently, the label can be RF scanned or optically scanned.  
         [0008]     In a second embodiment, a protective patch is included between the RFID chip and the surface of the container to protect the RFID chip from the heat and physical forces received from the molten polymer during molding of the container. The antenna may be printed on either the second surface of the label stock, or on the protective patch.  
         [0009]     The present invention provides an RFID assembly that is cost effective and relatively easy to manufacture because the labels can simply be attached to the exterior surface of a plastic container during molding of the container. In addition to providing RFID capabilities, the labels provide a location to include both aesthetic and functional printed information, such as a barcode or a corporate logo.  
         [0010]     These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the current embodiments and the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a perspective view of an RFID label attached to a waste container according to one embodiment of the present invention.  
         [0012]      FIG. 2  is a front view of an RFID label according to one embodiment of the present invention.  
         [0013]      FIG. 3  is a front perspective view of the RFID label.  
         [0014]      FIG. 4  is a rear perspective view of the RFID label.  
         [0015]      FIG. 5  is a rear perspective view of an RFID label including a protective patch.  
         [0016]      FIG. 6  is an exploded view of another embodiment of the label wherein an antenna and RFID chip are attached to the protective patch.  
         [0017]      FIG. 7  is a rear perspective view of the  FIG. 6  embodiment showing the antenna and RFID chip in broken lines.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     I. Overview  
         [0019]     An RFID label according to the present invention is shown in  FIG. 2  and generally designated  10 . In general, the label includes a web of label stock  12 , an antenna  14 , and an RFID chip  16 . Shown in  FIG. 1 , the web  12  is attached to the surface of a container  18 , such that the antenna  14  and RFID chip  16  are between the label  10  and the surface of the container  18 .  
         [0020]     II. Structure  
         [0021]     The web  12  is typically a section of sheet material that is cut to a desired size and shape. The web  12  is generally a polymeric sheet stock, such as 0.0065 in. thick polyethylene sheet stock. The web  12  includes a first surface  20  and a second surface  22 . As shown, the first surface  20  includes printed information, such as a barcode  24 . In addition to the barcode  24 , the first surface may include a variety of other printed information, such as a corporate logo  25  or other marks of product identification. One or both of the surfaces may be coated with a variety of coatings. For instance, one or both surfaces may be coated with an ink primer coat before any printed information or other material is printed on the surface. In the illustrated embodiment, the first surface  20  is coated with a primer coat (not shown) before the printed information is applied. In a similar fashion, one or both of the surfaces may be Corona treated before the application of any ink. Corona treatment is a known process wherein the surface energy of the web  12  is altered, but the material properties stay the same. This treatment allows the surface to receive ink, such as the printed antenna  14  described below, while still allowing the polyethylene surface  22  to attach to the injection molded surface of a container. In the illustrated embodiment, only the second surface  22  is Corona treated. In addition, a protective UV coating (not shown) may be applied to one or both surfaces to prolong the life of the label  10 . In the illustrated embodiment, a UV coating is applied to the first surface  20 .  
         [0022]     The antenna  14  is conventional, and is typically printed on the second surface  22  of the web  12  with a conductive ink, such as a silver based ink manufactured by Precisia, Inc. As described above, the second surface  22  is typically Corona treated prior to the application of the antenna  14  so that the ink antenna attaches to the surface  22 , and so that the surface  22  is still able to attach to another plastic surface, such as the surface of an injection molded container. The antenna  14  may extend along the second surface  22  of the web  12  in a variety of desired patterns; however, the size and shape are generally chosen to maximize the transmission distance of the chip. Shown in  FIG. 4 , the antenna is printed in two halves that terminate proximate to each other at a pair of electrical contact points  27 ,  29  for connection to the RFID chip  16 .  
         [0023]     The RFID chip  16  is also conventional, and therefore will not be described in great detail. In short, the chip  16  is a programmable semiconductor, such as an EPC Class 1 915 MHz chip manufactured by Alien Technology. As shown in  FIG. 4 , the chip  16  may be attached to a plastic substrate  17 , known in the industry as a strap, that includes a pair of electrically conductive pads  31 ,  33  for connecting the chip to the antenna  14 . As shown in  FIG. 4 , the strap is attached to the antenna  14  such that the electric leads  27 ,  29  on the antenna  14  are in electrical connection with the pads  31 ,  33  on the strap  17 . In one embodiment, the strap is attached to the antenna  14  with a conductive adhesive (not shown). In another embodiment, the electrical connections may be soldered together.  
         [0024]     In one embodiment, shown in  FIGS. 5-7 , a protective patch  26  may be attached to the second surface  22  of the web  12 . The protective patch  26  may be comprised of a variety of materials. In one embodiment, the protective patch  26  is comprised of the same label stock as the web  12 . The protective patch includes a first surface  28  and a second surface  30 . The first surface  28  of the patch  26  is attached to the second surface  22  of the web  12 , for instance, with an adhesive, such that it covers at least the strap  17 . As shown in  FIG. 5 , the protective patch covers the strap  17 , the RFID chip  16 , and a portion of the antenna  14 . In another embodiment, shown in  FIGS. 6 and 7 , the antenna  14  may be printed on the first surface  28  of the protective patch  26 , and the strap  17  attached to the antenna  14  on the patch  26  such that the electrical pads  31 ,  33  connect to the leads  27 ,  29  on the antenna  14 . In this embodiment, the patch  26 , antenna  14  and chip  16  are attached as a unit to the second surface  22  of the web  12 . As with the web  12 , one or both surfaces of the protective patch  26  may be coated or treated with one or more coatings.  
         [0025]     The container  18  is thermoformed plastic, typically formed by molding, such as injection molding, roto molding, vacuum molding or blow molding. In the illustrated embodiment, the label  10  is shown attached to a conventional waste container  18 ; however, the label  10  may alternatively be attached to a wide variety of injection molded products. The label  10  is generally attached to the container by one of two methods. In a first method, a pressure sensitive adhesive is applied to the second surface  22  of the label and the label  10  is then adhered to the container  18 . In a second method, the label is “in-molded”  18  during the molding process, such that the second surface  22  is bonded to a surface of the container  18 . In-molding is a process in which the label is placed in the mold before the plastic material is injected or otherwise placed into the mold. With suitable material selection, the label physically bonds with the injected plastic material. Alternatively, a heat-activated adhesive may be applied to the reverse side of the label, in which case the adhesive would be activated by the injected plastic. Appropriate in-molding techniques are known to those skilled in the art. As the plastic cools and cures, the second surface  22  of the label  10  remains attached to the surface of the container  18 , with the antenna  14  and RFID chip  16  disposed between the label  10  and container  18 .  
         [0026]     III. Manufacture  
         [0027]     Manufacture of the label  10  includes the steps of 1) preparing the surfaces of the web  12 , 2) applying printed material to the surfaces of the web  12 , 3) attaching an RFID chip to the web  12 , and 4) attaching the web  12  to a plastic structure.  
         [0028]     Preparing the surfaces of the web  12  typically involves applying a primer coat to the first surface  20  and Corona treating the second surface  22 . Alternative coatings are also known. The desired printed information, such as a barcode  24  and corporate logo  25 , are applied to the front surface  20 , and the antenna  14  is printed on the second surface  22 . Conventional printers are used for both applications. As described above, in an alternative embodiment, the antenna may be printed on a separate protective patch  26 .  
         [0029]     The strap  17  is then attached to the antenna  14 . This is typically done by applying a conductive adhesive to either the strap  17  or the antenna  14  and then pressing the two together with the electrical contacts aligned. In the embodiment including a protective patch  26 , wherein the antenna  14  is printed on the protective patch  26 , the chip  26  may be attached to the protective patch  26 . The protective patch  26  is adhered to the second surface  22  of the web  12  with a conventional adhesive.  
         [0030]     The label  10  is then attached to the substrate of a plastic structure, such as the waste container  18 , by a pressure sensitive adhesive or during the injection molding process. The pressure sensitive adhesive method involves applying the adhesive to the second surface  22  of the label  10  and placing the label  10  on the container  18 . In the in-mold method, one or both surfaces of the label may be provided with a static charge so it will stick to the surface of a mold. The label  10  is placed in the mold with the second surface  22  facing the mold cavity, and the first surface  20  bearing against the mold. The molten plastic is injected into the mold to contact the second surface  22  and to encapsulate the top  38 , bottom  32 , and side edges  34 ,  36  of the label  10 . The second surface  20  remains exposed. As the plastic cures, the RFID enabled label is attached to the plastic structure.  
         [0031]     The above description is that of the current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.