Transponder device and a label for on-metal labelling

Abstract

A transponder device suitable for use on metal surfaces is described here. The transponder device is comprising a monopole (or "Marconi"-) antenna structure with a radiating part protruding from the metal surface and a grounded plane, which is attached to the metal surface. The transponder device further comprises a floating element, which is separating the radiating element and the ground plane. The floating element is neither conductively connected to the antenna structure nor the metal structure. The transponder device allows for enhanced performance on metal surfaces.

Description

TRANSPONDER DEVICE AND A LABEL FOR ON-METAL LABELLINGCross-Reference to Related Application

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 63 / 584,566 filed September 22, 2023, which is incorporated by reference herein in its entirety.Background

[0002] Transponders are used in secure supply chains in order to control the supply chain, in retail as identifiers in shop management or even for automatized check-out. The functioning of the transponders is often disturbed because packaging materials or contents of packages cause detuning or attenuation and as a consequence, the transponder does not work properly. Furthermore, different retail products have different dielectric characteristics and therefore different effect on electrical components, such as transponders. For example, on metal surfaces or on some other surfaces which have high RF losses, the transponders do not work at all.

[0003] In some cases, the problem can be solved by manufacturing a suitable transponder for each application, but it is naturally an expensive way to solve the problem. It is also possible to use a dielectric material to de-couple the transponder from a metal underground. But doing so will make the label comprising the transponderthicker but then it is impossible to printthe label byTTR (thermal transfer ribbon) printers or barcode printers, which are conventionally used by package manufacturers, such as CPG (consumer package goods) manufacturers. Different returnable transport items are often collected in the same place, and it is cumbersome if all types of the items require a tailored transponder.

[0004] Besides the solutions in which thickness is increased, certain hard materials or encapsulations have been used. Such labels can be neither printed nor attached automatically. Further, they are expensive.

[0005] Also a bent label has been introduced. It is intended to be attached to a target surface (in this application the target surface means any surface to which a label is attached) in such a manner that it is attached to the surface from its both ends, and the middle of the label is loose from the surface. A problem with the bent label is that it is difficult to attach to the target surface, and a bent antenna does not work as well as a straight antenna. Further, the loose part of the label is easily torn.

[0006] U.S. Publication No. 2003 / 0080917 discloses a dielectric shielding for improved RF performance of RFID. The shielding is formed from a release liner which remains between the transponder and the target surface, or the shielding is formed from a portion of a face sheet which is folded upon itself.Summary

[0007] Embodiments of the invention seek to overcome above disadvantages by providing a flat label which comprises an RFID transponder device - or inlay - that can be attached to a metal surface, e.g. a metal pouch, metal packaging, metal can, etc.

[0008] The transponder device comprises an IC and an antenna structure on a dielectric substrate, e.g. PET or Paper. The IC is coupled to an antenna structure made from an electrically conductive material, such as Copper, Aluminium, Gold, Silver, Graphene, or conductive inks. The antenna structure comprises a radiating element, which is designed to not attach to the metal surface. It can either reach over the edge of the metal surface in case the transponder device is placed near the edge of it or it can be bent to be oriented in an angle away from the metal surface. The metal surface would interact with the antenna and affect it negatively. In order to prevent this, the radiating part of the transponder device should be sticking out from said metal surface, either over its edge or in an angle. The transponder device also comprises a ground plane designed to attach to the metal surface and being electrically grounded by said metal surface. For the transponder device to optimally work, the ground plane should be grounded, as opposed to the radiating element. As a result, the dipole antenna will turn into a monopole antenna, which mimics a dipole. This principle is known from long-range communication antennas. The performance increases greatly over other on-metal solutions described above.

[0009] However, embodiments of the invention can also be used like a normal dipole UHF RFID tag when placed on non-metal surfaces, e.g. paper or cartonnage. In this case the radiating element may also be attached to the surface, sticking out over the edge or an angle towards the surface is not necessary in this case.

[0010] To further improve the on-metal performance, embodiments of the invention suggest the transponder device to further comprise an electrically connected element located between the ground plane and the radiating element and electrically insulated from the metal surface, so it is not grounded by said metal surface. This element can be arranged close to the ground plane and in parallel to one of its sides. This element will add additional degrees of freedom to the impedance of the antenna structure and enables better performance on metal surfaces.

[0011] Further, embodiments of the invention suggest the transponder device to further comprise a floating element used to separate the radiating element and the ground plane, wherein the floating element is not conductively connected to the antenna structure. The floating element interacts with the ground plane (or ground when attached to a metal surface) and the radiating element only by means of capacitive or inductive coupling. There is no conductive connection between the other elements of the transponder device and thee floating element.

[0012] In some embodiments, the transponder device the ground plane is at least half the size of the device. This can be determined either by the area or the side-length measured from the ground plane in direction of the radiating element

[0013] In some embodiments, the ground plane has a rectangular shape. In some embodiments it may have a square shape. In yet another embodiment it may have a circular or oval shape.

[0014] In some embodiments, the radiating element may be arranged in parallel to a longer side of the rectangular ground plane. In other embodiments the radiating element may be arranged in parallel to a smaller side of the rectangular ground plane.

[0015] In some embodiments, the floating device has a gap of at least 1.2 mm between the ground plane and the floating device. A sufficient gap ensures stability of the performance of the transponder device.

[0016] In some embodiments, the transponder device comprises an additional meandered element, which introduces more degrees of freedom for improved tunability.

[0017] Embodiments of the invention also include a label comprising a transponder device as described above. A label may be the transponder device laminated on one side with a material which can display readable information. The information can be letters and ciphers readable for a human user or machine-readable code, e.g. a barcode. In retail the information for a human user may be a pricing information. In some situations, it may be that additionally to the information of the RFID transponder device some information must be optically readable for machines e.g. check-out systems.

[0018] In some embodiments the label may be suitable to be printed on by a label printer, laser printer or inkjet printer. In contrast to on-metal transponders of prior art the transponder device as described above is very thin (thin as paper or paper labels) and can be used with label printers, laser printers or inkjet printers. Further, the label can be manufactured in such a manner that only minor changes or no changes at all are required in the manufacturing lines. Thus, the manufacturing process of the label according to embodiments of the invention is cost-effective.

[0019] In some embodiments the section of the label comprising the part of the transponder device may be foldable and designed to firmly stay in the folded position. For the radiating element itis important to not interact with the metal surface to work properly. The label / transponder device can either be placed in a way that allows the radiating element to stick out over the edge of the metal surface or be arranged in an angle away from the metal surface (preferably > 45°, ideally 90° from the metal surface).

[0020] In some embodiments the label is comprising a layer of sturdy paper or thin cartonnage. The transponder device or the substrate may be covered with an adhesive and then attached to a sheet or layer of relatively stiff paper. In some embodiments there can be a perforation or folding line between the ground plane and the radiating element. This may be advantageous to keep the radiating part in its position and prevent an unwanted interaction with the metal surface.

[0021] In some embodiments the label may be self-adhesive in the area of the ground-plane of the transponder device and non-adhesive in the area of the radiating element of the transponder device. In some embodiments the adhesive may be a conductive adhesive.Description of the figures

[0022] Fig. 1: Schematic drawing of an example of inventive transponder inlay;

[0023] Fig. 2: Schematic drawing of another example of the transponder inlay; and

[0024] Fig. 3: Schematic drawing of a third example of the transponder inlay.Detailed description of the drawings

[0025] Fig. 1 depicts a schematic drawing of the inventive transponder inlay. The transponder device comprises an IC 2 connected to the antenna structure 1+3+4. The ground plane 3 will interact either conductively, inductively or capacitively with a metal surface. By that the ground plane is being grounded. The presence of a grounded ground plane allows the radiating element 1 to operate as a monopole antenna with the electrical equivalent to a dipole antenna. Image currents and fields add in a positive manner since the ground plane behaves like an electromagnetic mirror, which generates an electric field above the metal ground. Ground plane 3 and radiating element 1 are connected by an electrically connected element 4, which is used for frequency resonance tuning. Further the transponder device comprises the floating element 5, which may have a clearance to the ground plane 3 of at least 1.2 mm. The floating element is stabilizing the performance of the transponder device on different metal surfaces with different electrical conductivity. Only the ground plane 3 is grounded. Connected element 4, floating element 5 and radiating element 1 are not grounded. The transponder device can be mounted on the metal surface such that radiating element 1 is sticking out over the edge of the metal surface.

[0026] Fig. 2 depicts the schematic drawing of a further example of the inventive transponder device. When miniaturizing the transponder device limitations in tunability arise. The additional meandered element 6 introduces additional grades of freedom that increase the tuneability of the transponder device.

[0027] Fig. 3 depicts the schematic drawing of a further example of transponder device according to an embodiment of the invention. Here the ground plane is significantly smaller. This embodiment may be used for difficult metal surfaces that do not offer a large, plain area of metal.

Claims

ClaimsWhat is claimed is:

1. A transponder device suitable for use on metal surfaces, the device comprising an IC and an antenna structure on a dielectric substrate, the IC coupled to an antenna structure, characterized by the antenna structure comprising:- a radiating element designed to not attach to the metal surface and sticking out from said metal surface- a ground plane designed to attach to the metal surface and being electrically grounded by said metal surface- an electrically connected element located between the ground plane and the radiating element and electrically insulated from the metal surface, so it is not grounded by said metal surface, wherein the grounded ground plane and the radiating element are designed to work as a monopole antenna and the transponder device further comprising a floating element used to separate the radiating element and the ground plane, wherein the floating element is not conductively connected to the antenna structure.

2. The transponder device of claim 1, characterized by the ground plane being at least half the size of the device.

3. The transponder device of claim 1, characterized by the ground plane having a rectangular shape.

4. The transponder device of any of claims 1-3, characterized by the radiating element being arranged in parallel to a longer side of the rectangular ground plane.

5. The transponder device of any of claims 1-4, characterized by the radiating element being arranged in parallel to a smaller side of the rectangular ground plane.

6. The transponder device according to any of the previous claims, characterized by the gap between the ground plane and the floating element being at least 1.2 mm.

7. The transponder device according to any of the previous claims, characterized by the transponder device further comprising a meandered element between the ground plane and the electrically connected element, said meandered element connected conductively to both the ground plane and the electrically connected element.

8. A label comprising a transponder device suitable for use on metal surfaces, the device comprising an IC and an antenna structure on a dielectric substrate, the IC coupled to an antenna structure, characterized by the antenna structure comprising:- a radiating element designed to not attach to the metal surface and sticking out from said metal surface- a ground plane designed to attach to the metal surface and being electrically grounded by said metal surface- an electrically connected element located between the ground plane and the radiating element and electrically insulated from the metal surface, so it is not grounded by said metal surface, wherein the grounded ground plane and the radiating element are designed to work as a monopole antenna and the transponder device further comprising a floating element used to separate the radiating element and the ground plane, wherein the floating element is not conductively connected to the antenna structure.

9. The label of claim 8, characterized by the label being suitable to be printed on by a label printer, laser printer or ink jet printer.

10. The label of claim 8 or 9, characterized by the section of the label comprising the radiation element of the transponder device being foldable and designed to firmly stay in the folded position.

11. The label of one of the claims 8 to 10, characterized by the label comprising a layer of sturdy paper or thin cartonnage.

12. The label of one of the claims 8 to 11 characterized by the label being self-adhesive in the area of the ground plane of the transponder device and being non-adhesive in the area of the radiating element of the transponder device.

13. The label of claim 12, characterized by the adhesive being a conductive adhesive.

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