Edge on foam tags

An RFID antenna structure is disclosed that is designed to operate in proximity to metal surfaces. The RFID antenna structure is placed at 90 degrees to the surface of the metallic object, allowing it to operate with minimal separation from the edge of the RFID antenna structure to the metallic object. In another embodiment, the RFID antenna structure comprises an anti-tamper embodiment wherein a RFID tag device is applied to twist and flip-top cap containers, such that tearing along the perforations on the cap disables the RFID tag device.

BACKGROUND OF THE INVENTION

The present invention relates generally to a radio-frequency identification (RFID) antenna that is designed to operate in proximity to metal surfaces. Specifically, the antenna is positioned at 90 degrees to the surface, allowing the antenna to operate with minimal separation from the edge of the RFID antenna to the metallic object. The present subject matter is especially suitable for food and medication containers. In accordance with embodiments of the present subject matter, an RFID antenna is provided that is designed to operate in proximity to conductive surfaces, with the surfaces including high dielectric constant and high dielectric loss, such as some liquids, gels, solutions, and combinations of these surfaces and material. Particular relevance is found in connection with sealed food and medication containers. Accordingly, the present specification makes specific reference thereto. However, it is to be appreciated that aspects of the present inventive subject matter are also equally amenable to other like applications.

Radio-frequency identification (“RFID”) is the use of electromagnetic energy (“EM energy”) to stimulate a responsive device (known as an RFID “tag” or transponder) to identify itself and in some cases, provide additionally stored data. RFID tags typically include a semiconductor device commonly called the “chip” on which are formed a memory and operating circuitry, which is connected to an antenna. Typically, RFID tags act as transponders, providing information stored in the chip memory in response to a radio frequency (“RF”) interrogation signal received from a reader, also referred to as an interrogator. In the case of passive RFID devices, the energy of the interrogation signal also provides the necessary energy to operate the RFID device.

RFID tags may be incorporated into or attached to articles to be tracked. In some cases, the tag may be attached to the outside of an article with adhesive, tape, or other means and in other cases, the tag may be inserted within the article, such as being included in the packaging, located within the container of the article, or sewn into a garment. The RFID tags are manufactured with a unique identification number which is typically a simple serial number of a few bytes with a check digit attached. This identification number is incorporated into the tag during manufacture. The user typically cannot alter this serial/identification number and manufacturers guarantee that each serial number is used only once. This configuration represents the low cost end of the technology in that the RFID tag is read-only and it responds to an interrogation signal only with its identification number. Typically, the tag continuously responds with its identification number. Data transmission to the tag is not possible. These tags are very low cost and are produced in enormous quantities.

Such read-only RFID tags typically are permanently attached to an article to be tracked and, once attached, the serial number of the tag is associated with its host article in a computer data base. The RFID tag data, both a unique ID and data stored in a read/write memory, may also be associated in a database with a host article, but not always. The tag may store data read from a bar code, or the item identification, its manufacturing date etc. and have no association with a database or requirement to access one.

Read only tags, those that respond with a pre-programmed code when powered up at a regular or pseudo random interval, are no longer commonly used.

Most tags now incorporate chips that include both read only memory, that usually contains configuration bits, manufacturers ID, chip model number and a unique ID ranging between 2 and 9 bytes in length, and read write memory commonly between 12 and 16 bytes, although larger memories may be used. The unique ID is used in combination with the manufacturers ID and chip model number (two different chip manufacturers could use the same unique ID).

Specifically, an object of the tag is to associate it with an article throughout the article's life (the tag may be applied at any point in the supply chain, not necessarily for the articles life) in a particular facility, such as a manufacturing facility, a transport vehicle, a health care facility, a pharmacy storage area, or other environment, so that the article may be located, identified, and tracked, as it is moved. Tracking the articles through the facility can assist in generating more efficient dispensing and inventory control systems as well as improving work flow in a facility. This results in better inventory control and lowered costs. In the case of medical supplies and devices, it is desirable to develop accurate tracking, inventory control systems, and dispensing systems so that RFID tagged devices and articles may be located quickly should the need arise, and may be identified for other purposes, such as expiration dates or recalls.

Many RFID tags used today are passive in that they do not have a battery or other autonomous power supply and instead, must rely on the interrogating energy provided by an RFID reader to provide power to activate the tag. Passive RFID tags require an electromagnetic field of energy of a certain frequency range and certain minimum intensity in order to achieve activation of the tag and transmission of its stored data. Another choice is an active RFID tag; however, such tags require an accompanying battery to provide power to activate the tag, thus increasing the expense and the size of the tag and making them undesirable for use in a large number of applications.

Depending on the requirements of the RFID tag application, such as the physical size of the articles to be identified, their location, and the ability to reach them easily, tags may need to be read from a short distance or a long distance by an RFID reader. Furthermore, the read range (i.e., the range of the interrogation and/or response signals) of RFID tags is also limited.

Furthermore, when the RFID tags are attached to a conductive surface, an RFID tag may have difficulties in being read. In those situations where reading a tag is problematic, such as where the space between a dipole and its image is small reducing the space creates difficulty in reading the tag, such as where the space is very small (less than one wavelength), then the total effective current between the dipole and its image is equal to zero or near zero. As the spacing between the antenna and the metal plane decreases the efficiency of the antenna reduces and it becomes difficult to achieve an impedance match to a device such as an RFID chip over a useful bandwidth. The issues become more apparent when the spacing is ˜<1% of one wavelength; these problems can be mitigated to some extent by using a separator between the antenna and plane. For example, a high dielectric constant material may be used, or a material with both a high dielectric constant and high relative permeability, to increase the effective separation. However, such materials are expensive, and not suitable for RFID tags, where lower cost materials, such as papers/card, simple plastics such as PET and polypropylene foams are more desirable; all of these have relatively low dielectric constants.

Thus, the total radiated field is negligible and therefore, the RFID tag is unable to capture data and power from the reader. This is a significant problem given that in many commercial applications it is desirable to apply the RFID tag to a metal or other type of conductive surface. What is needed therefore is an RFID tag device and/or system that allows the RFID tag to operate in proximity to metal surfaces or other types of conductive surfaces.

The present invention discloses an RFID antenna structure that is designed to operate in proximity to metal surfaces. The RFID antenna structure is placed at 90 degrees to the surface of the metallic object, allowing it to operate with minimal separation from the edge of the RFID antenna structure to the metallic object.

SUMMARY

The subject matter disclosed and claimed herein, in one aspect thereof, comprises an RFID antenna structure that is designed to operate in proximity to metal surfaces. The RFID antenna structure is placed at 90 degrees to the surface of the metallic object, allowing it to operate with minimal separation from the edge of the RFID antenna structure to the metallic object.

In a preferred embodiment, the RFID antenna structures may be thin and formed into a number of shapes depending on the form factor used. Specifically, the RFID antenna structure can be linear and incorporated into a protective plastic layer by extrusion, wrapped in a number of shapes, wrapped around a form and placed in a cavity, or incorporated into a structure by injection molding. In another embodiment, the container comprises an anti-tamper (or tamper evident) embodiment wherein the RFID tag device is applied to twist and flip-top cap containers, wherein tearing along the perforations on the cap disables the RFID tag device.

DETAILED DESCRIPTION

The present invention discloses an RFID antenna structure that is designed to operate in proximity to metal surfaces. The RFID antenna structure is placed at 90 degrees to the surface of the metallic object, allowing it to operate with minimal separation from the edge of the RFID antenna structure to the metallic object. Furthermore, the RFID antenna structures may be thin and formed into a number of shapes depending on the form factor used. Specifically, the RFID antenna structure can be linear and incorporated into a protective plastic layer by extrusion, wrapped in a number of shapes, wrapped around a form and placed in a cavity, or incorporated into a structure by injection molding.

Referring initially to the drawings,FIG. 1illustrates the RFID antenna structure100that is designed to operate in proximity to metal surfaces. The RFID antenna structure100is placed at 90 degrees (or any other suitable distance) to the surface of the metallic object, allowing it to operate with minimal separation from the edge102of the RFID antenna structure100to the metallic object. The RFID antenna structure100can comprise any suitable antenna as is known in the art, such as, but not limited to, a dipole antenna. Specifically, the RFID antenna structure100is formed from an RFID inlay that can be adhered to a material such as paper, plastic, or foam, such as, but not limited to, an Avery Dennison 160u7 inlay. The RFID inlay comprises an RFID chip and aluminum, copper or silver antenna bonded to a polyethylene terephthalate (PET) layer or other suitable layer as is known in the art. The RFID inlay can then be adhered to the back side of a label or other suitable material and printed and encoded in an RFID printer.

The RFID antenna structure100can be any suitable size, shape, and configuration as is known in the art without affecting the overall concept of the invention. One of ordinary skill in the art will appreciate that the shape and size of the antenna structure100as shown inFIG. 1is for illustrative purposes only and many other shapes and sizes of the antenna structure100are well within the scope of the present disclosure. Although dimensions of the antenna structure100(i.e., length, width, and height) are important design parameters for good performance, the antenna structure100may be any shape or size that ensures optimal performance and sensitivity during use.

As illustrated inFIG. 2, the RFID antenna structure100is shown on a metallic object200. The RFID antenna structure100is placed at 90 degrees to the surface of the metallic object200, allowing it to operate with minimal separation from the edge202of the RFID antenna structure100to the metallic object200. With reference now toFIG. 3, there is illustrated a graph of the performance of the RFID antenna structure on both a metal surface and a non-metal surface.

With reference now toFIG. 4, there is illustrated the RFID antenna structure100in use with medication container. The RFID antenna structure100is formed into a circle and positioned within the interior of the lid400of the medication container. Specifically, the RFID antenna structure100is positioned against the threads402of the lid400. Thus, once the lid400is screwed on the container, the edge202would contact the metal foil sealing disk of the container creating an edge on to the metallic surface. Typically, the RFID antenna structure100comprises a biaxially polypropylene (BOPP) face and a permanent adhesive to secure the RFID antenna structure100in the lid400, however any other suitable materials can be used as is known in the art.

FIG. 5illustrates the RFID antenna structure100positioned in the same orientation but within a larger lid500of a medication container. Further, the action of the lid threads402engaging when the lid500is screwed on does not destroy the RFID antenna structure100, and even after multiple tries, as well as over-tightening the lids400and500, the RFID antenna structure100still functions. With reference now toFIG. 6, there is illustrated a graph of the performance of the RFID antenna structure edge on to a foil sealing disk.

With reference now toFIGS. 7A-B, the RFID antenna structure700is shown. Specifically,FIG. 7Adiscloses the RFID antenna structure700configured as an RFID inlay702sandwiched between two sheets of material704, such as paper, plastic, or foam. Specifically, the material is typically laminated around the material704and then cut into shapes, such as circles, rectangles, hexagons, triangles, etc., or any other suitable shape as is known in the art. When mounted on a metal surface so that the edge706of the RFID inlay702is in proximity to the metal surface, good performance is achieved.

FIG. 7Bdiscloses a side view of the RFID antenna structure700. The RFID inlay702is shown sandwiched between two layers of material704(i.e., paper, plastic, or foam). Thus, the RFID inlay702is capable of operating on metal surfaces when made by flat roll to roll lamination and slitting or die cutting, or any other suitable method as is known in the art.

With reference now toFIG. 8, the RFID antenna structure800is shown wrapped around a shape. Specifically,FIG. 8discloses the RFID antenna structure800configured as an RFID inlay802which is wrapped around a round object804, such as a plastic disk or any other suitable shape as is known in the art. If the disk has a hole, then the RFID inlay802can be wrapped around an internal surface of the disk, such as a thread or other area. The RFID inlay802in either configuration is then placed in edge on proximity to a metal surface806, such as a foil disk used to seal a medicine container, or any other suitable metal surface as is known in the art.

With reference now toFIG. 9, the RFID antenna structure900is shown extruded inside a plastic strip904. Specifically,FIG. 9discloses the RFID inlay902extruded into a plastic strip904, wherein the RFID inlay902is positioned down the center of the extrusion.FIG. 9shows a triangular cross-section, but alternate multi-sided shapes can be used as well, as is known in the art. The RFID inlay902is then placed on its edge906proximate to any suitable metal surface as is known in the art.

With reference now toFIG. 10, the RFID antenna structure1000is disclosed as being wound helically around a narrower former. Specifically, in order to reduce the diameter of the structure without making the ends of the RFID inlay1002overlap, the RFID inlay1002is wound helically around a narrower plastic former1004. This plastic former1004can include a hole1006to allow the structure1000to be fixed by a bolt or screw to a surface, or any other attachment means as is known in the art. The RFID inlay1002is then able to be mounted such that the edge of the RFID inlay1002is in proximity to the metal surface.

With reference now toFIG. 11, the RFID antenna structure1100is disclosed as being formed into a flat spiral. Specifically, the RFID inlay1102is wound into a flat edge spiral that can be attached to a metal surface1106. Thus, the RFID inlay1102in the shape of a spiral can be placed edge on a metal surface1106to achieve good performance of the antenna structure1100.

With reference now toFIGS. 12A-B, the RFID antenna structure1200is shown as being attached to a metal surface in different mounting orientations. Specifically, the figures show an RFID inlay1202embedded within a plastic material1204, or any other suitable material. The embedded RFID inlay1202has two mounting surfaces that can be attached to a metal surface1206. Depending on which surface is attached, the tuning and other properties of the RFID antenna structure1200can be changed. Further, other structures such as a hexagonal cross-sectional structure, allow multiple mounting orientations which can give different tuning states.

With reference now toFIGS. 13A-C, the RFID antenna structure1300is applied to twist cap containers1302as a tamper evident device. Specifically, as shown inFIG. 13A, a label1304is positioned over a twist cap1306and over the container (or bottle)1302neck with an RFID inlay1308positioned only over the container (or bottle)1302. A perforation strip1310is engineered over the label1304and the RFID inlay1308. Twisting of the cap1306to expose the container1302opening, propagates the tearing in and along the weakened path (i.e., perforation strip1310) across and down through the label1304and inlay1308on the container1302, disabling the inlay1308(as shown inFIG. 13B). Thus, the RFID inlay1308is disabled when the cap1306is twisted off (i.e., the bottle is opened).

Furthermore, the perforation strip1310can be any engineered path that propagates a tear along a predetermined path, such that the predetermined path may be defined as any designed/engineered weakening in the label/inlay construction. In a preferred embodiment, the weakening is by perforation or scoring of certain layers in the label/inlay construction. In a further embodiment shown inFIG. 13C, the label1304comprises no or a reduced adhesion in certain areas1312. These areas1312of little or no adhesive facilitate ease of separation of the perforated path through the label1304and inlay1308.

With reference now toFIGS. 14A-B, the RFID antenna structure1400is applied to fliptop cap containers1402as a tamper evident device. Specifically, as shown inFIG. 14A, a label1404is positioned over a flip-top cap1406and over the container (or bottle)1402neck with an RFID inlay1408positioned over the flip-top can1406and over the container (or bottle)1402as well. A perforation strip1410is engineered over the label1404and the RFID inlay1408. Flipping open the cap1406to expose the container1402opening, propagates the tearing in and along the weakened path (i.e., perforation strip1410) across and down through the label1404and inlay1408on the container1402, disabling the inlay1408(as shown inFIG. 14B). Thus, the RFID inlay1408is disabled when the cap1406is flipped open (i.e., the bottle is opened). Furthermore, the perforation strip1410can be any engineered path that propagates a tear along a predetermined path, such that the predetermined path may be defined as any designed/engineered weakening in the label/inlay construction. In a preferred embodiment, the weakening is by perforation or scoring of certain layers in the label/inlay construction.

With reference now toFIGS. 15A-C, the RFID antenna structure1500is applied to fliptop cap containers1502as a tamper evident device. Specifically, as shown inFIG. 15A, a label1504is positioned over a flip-top cap1506and over the container (or bottle)1502neck with an RFID inlay1508positioned only over the container (or bottle)1502. A perforation strip1510is engineered over the label1504and the RFID inlay1508. Flipping open the cap1506to expose the container1502opening, propagates the tearing in and along the weakened path (i.e., perforation strip1510) across and down through the label1504and inlay1508on the container1502, disabling the inlay1508(as shown inFIG. 15B). Thus, the RFID inlay1508is disabled when the cap1506is flipped open (i.e., the bottle is opened).

Furthermore, the perforation strip1510can be any engineered path that propagates a tear along a predetermined path, such that the predetermined path may be defined as any designed/engineered weakening in the label/inlay construction. In a preferred embodiment, the weakening is by perforation or scoring of certain layers in the label/inlay construction. In a further embodiment shown inFIG. 15C, the label1504comprises no or a reduced adhesion in certain areas1512. These areas1512of little or no adhesive facilitate ease of separation of the perforated path through the label1504and inlay1508.