Patent Publication Number: US-2009237211-A1

Title: Security and identification tags

Description:
TECHNICAL FIELD 
     This invention relates to security tags that can be applied to articles for theft prevention, inventory tracking, etc. Such tags includes radio-frequency and magnetic EAS (electronic article surveillance) tags, radio-frequency identification (RFID) tags, and the like. In particular, the invention relates to such tags that are suitable for use on items such as cases for compact discs (CDs), digital versatile discs (DVDs), Video Games, and the like. The term ‘security tag’ is used here for both EAS and RFID tags. 
     BACKGROUND ART 
     EAS tags are well-known as anti-theft devices. Radio-frequency EAS tags essentially comprise an LC tank circuit with a resonance peak at a predetermined frequency. Detection is achieved by sweeping an rf field around the predetermined frequency and detecting a dip due to the presence of the tag. The tags are deactivated by submitting them to a strong FM field to induce voltages exceeding the capacitor&#39;s breakdown voltage. 
     One common use for EAS tags is in securing and tracking books, CDs, DVDs and the like in retail outlets. Such tags are usually laid down on a thin flexible substrate that is inserted into a book or product package, or adhered to the outside of packaging or wrapping. A typical form of tag is a square or rectangular antenna with the electronic components located within the loop. 
     RFID tags have been known for some time and are routinely found in a number of uses for tracking and identification of items. An RFID tag typically comprises a loop antenna and a small electronic circuit including an integrated circuit chip having a unique code programmed into it. Passive RFID tags have no internal power source (battery). In use, an interrogating radio-frequency (RF) signal induces a current in the loop antenna which provides both power and data to the chip. The chip in turn provides an output signal to the antenna which is detected by the interrogating system. Active RFID tags include a small internal power source allowing them to communicate over greater ranges and store and process larger amounts of information in the chip. 
     One problem encountered with such devices when used on cases for CDs, DVDs, and Video Games is that the metallization layer on the disc interferes with the RF signals, reducing the power and range available. This problem is particularly evident at certain frequencies when the loop antenna overlies part of the disc. This problem conflicts with the desire to make the loop as large as possible to obtain a good signal. 
     Another problem encountered with packaging such as CD or DVD cases is that it is possible to open the package and remove the disc, making them vulnerable to theft. GB 2311053 A describes a security tag having an adhesive layer which can be wrapped around the opening edge of the package so as to both secure the security tag to the package and prevent opening of the package to remove the disc. 
     This invention is based on the recognition that the form of the tag can be configured to diminish the effect of the disc on signals and that the tag can be provided in a convenient form for use with packaging such as CD, DVD, or Game cases. 
     DISCLOSURE OF THE INVENTION 
     One aspect of the invention provides a tag comprising a loop antenna having a substantially triangular shape and an electronic component connected to and positioned within the loop antenna, the antenna and component comprising a flexible metal structure disposed on one face of a flexible substrate, the flexible substrate extending away from one side of the triangular loop antenna to form a flap such that, when the tag is positioned on a face of a package close to its edge, the flap can be wrapped around the edge of the package and onto its other face. 
     By providing the loop antenna with a substantially triangular shape, it is possible to position the tag on CD or DVD packaging (which is typically square or rectangular) in a corner region so as to have little or no overlap with the metallised surface of the disc and so avoid interference while still obtaining a relatively large loop for good signal reception. 
     The flexible substrate can be provided with an adhesive on the opposite face to that on which the tag is disposed so as to allow fixing on a package. 
     It is also preferred that the substrate is transparent and may also be provided with printing that can be viewed when the tag is fixed to packaging. 
     The adhesive is preferably a clear, semi-transparent, removable acrylic-based adhesive. 
     In one particularly preferred embodiment, several tags are provided on a backing strip from which they can be removed and placed onto packaging. In one format, the tags can be arranged in sequential order with the triangular loop antennae consistently on one side of the substrate. This format is preferable for use with automated application. In another format, the tags can be arranged in an alternating configuration on the strip to optimise use of space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a security tag according to one embodiment of the invention; 
         FIG. 2  shows a strip of security tags of the type shown in  FIG. 1 ; and 
         FIG. 3  shows an security tag of the type shown in  FIG. 1  when used on a CD case. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
       FIG. 1  shows one embodiment of an EAS tag according to the invention. The active part of the tag  10  comprises a loop antenna  11  in the form of a triangle, and an electronic component  12  connected to the antenna  11  and located within the loop. The active part  10  is formed from thin, flexible metallic structures, typically aluminium, disposed on one face of a flexible substrate  14 . The manner of forming such flexible structures on substrates is well-known for use in identification tag devices. The flexible substrate  14  is a clear plastic material. In the region of the active part  10 , the substrate  14  has a corresponding, but slightly larger, triangular shape. The part of the substrate  14  along one of the sides of the antenna  11  is extended to form a flap  15 . A printed section  16  is provided on the substrate adjacent the same side of the antenna  11 . This printed section  16  can carry security markings, branding or any other information. 
     The face of the substrate  14  opposite to that on which the tag and printed section are provided is coated with an adhesive to allow fixture to a package such as a CD or DVD case. The adhesive is preferably a clear, semi-permanent, removable, acrylic-based adhesive. Adhesives with good clarity and UV resistance are preferred. Such adhesives are known for applications such as these. 
     The intended use of the tag of  FIG. 1  is on a CD or Game case (discussed in more detail below). Consequently, the dimensions of the active part  10 , in particular those of the antenna  11  are selected such that, when placed on the case in a corner, little or none of the antenna overlies the disc. DVD and Game cases are often of different size and shape to CD cases so the dimensions for that application can be different. Also, the printed section  16  can be dimensioned so as to lie along the edge of the case when the flap  15  is wrapped around the case. 
     The particular operating characteristics of the identification tag device will depend upon the particular system being used. A number of standard systems are currently in use operating. EAS tags can be magnetic, magneto-acoustic, radio-frequency and microwave systems. RFID tags operate at various frequencies from low frequency tags operating at just over 100 kHz to microwave tags operating at just over 2 GHz. High frequency (13.56 MHz) systems are particularly preferred for uses in the present invention. 
       FIG. 2  shows one embodiment of a strip of tags that is considered as particularly convenient for use. A number of tags A 1-3 , B 1-3  are located releasably on a strip C. Because of the triangular shape of the antenna  11  and the underlying part of the substrate, alternate tags A, B are rotated by 180° such that the antennae lie alongside each other. This optimises the use of the strip C and keeps the overall length down. The strip C is coated in the usual manner to allow easy release of the tags A, B with the adhesive layer intact. 
       FIG. 3  shows a perspective view of the use of a tag  18  of the type shown in  FIG. 1  on a conventional CD case  20 . The case  20  has a base  22  to which a lid  24  is connected by way of a hinge  26 . 
     In the embodiment shown in  FIG. 3  the CD case  20  is secured in its closed position by way of the tag  18 . The tag  18  is secured to the case such that the active portion  10  is on the lid  24  and the flap  15  is wrapped around the edge  25  and onto the base  22 , the adhesive on the substrate  14  fixing the tag  18  to both the lid  24  and the base  22  such that the tag  18  has to be removed is before the lid  24  can be opened. The active part  10  is positioned in the corner of the lid  24  so that it does not overlie the disc in the case and so avoids the interfering effect of the metallised layer. The printed portion  16  lies along the edge  25 . 
     The triangular shape is relatively easy to manufacture and achieve the objective of not overlying the disc. However, the shape does not have to be a perfect triangle. Thus, the side closest to the disc can be curved to optimise the amount of space taken up by the antenna. 
     A system for using tags such as those described above will include a transmitter and central processing system and will be installed in the location of use, such as a store. 
     Changes can be made while remaining within the scope of the invention. For example, as is discussed above, the dimensions of the active part  10  can be selected according to the packaging to be secured.