Microwaveable inlay

Abstract

Microwaveable inlay comprising an RFID chip (2), an antenna (3) electrically or magnetically connected to it, and a first substrate (4) arranged parallel to the surface with shielding surfaces (5), wherein the RFID chip (2) with the antenna (3) is applied to the first substrate (4) and two adjacent shielding surfaces (5) each have a gap between them, characterized in that the shielding surfaces (5) on the first substrate (4) are arranged in such a way that they block any straight path through the shielding surfaces (5) that runs exclusively along the gaps.

Description

[0001] The present invention relates to a microwave-compatible inlay comprising an RFID chip, an antenna electrically or magnetically connected thereto and a first substrate arranged parallel to the surface with shielding surfaces, wherein the RFID chip with the antenna is applied to the first substrate and two adjacent shielding surfaces each have a gap between them.

[0002] Such an inlay is already known from EP 4 120 133 B1. It is intended for use on reusable microwave cookware. Such packaging enables the purchase of ready-to-eat, freshly prepared foods that are dispensed together with the cookware. This microwave cookware is typically issued in a deposit return system. The known inlay serves in a smart label to identify the cookware as belonging to the establishment and the associated deposit return system and can also be used to categorize the cookware.

[0003] The plan is for microwave cookware to be assigned to a specific restaurant to prevent unrelated cookware from accumulating at another provider. Furthermore, only cookware that is actually intended for return should be taken back. This is already being addressed in many different ways using RFID (radio frequency identification) chips, which are arranged in smart labels with an antenna on a substrate, thus forming an inlay.

[0004] Using a suitable read / write device, the RFID chip can be written to or read in the conventional way.

[0005] An RFID chip does not have its own power source; instead, its antenna receives energy for reading from the communication partner, which provides it via an electromagnetic field using a read / write device. This energy is sufficient to write to or read from the RFID chip's memory and send a response signal via the antenna.

[0006] EP 4 120 133 B1 addresses the problem that, during microwave heating, for example when ready-to-eat food is to be reheated, the microwave radiation is also coupled into the antenna. This radiation can transmit sufficient energy to damage or destroy the inlay. To this end, EP 4 120 133 B1 proposes providing an additional shielding element and placing it beneath the inlay so that the inlay is enclosed between shielding surfaces connected to the inlay and the underlying shielding element as long as it is contained in the microwave oven. However, this represents a disadvantage in that if the underlying shielding element is omitted, the inlay may be damaged.

[0007] To eliminate this source of error, another development proposes gluing the inlay to overlapping foil sections with a recess in the center of the ring-shaped antenna. This shields the RFID chip and antenna sufficiently, eliminating the need for an underlying shielding element, while the overlap allows communication to continue. While microwave radiation cannot pass through the space between the overlapping layers and is diverted by them, the waves from the inlay—if it is an HF (radio frequency) or NFC (near field communication) inlay—can still leave the inlay area and be detected by a reader.

[0008] It has been shown that HF / NFC communication in the 13.56 MHz range is possible, but that RFID inlays in the UHF (ultra-high frequency) range in the 860-960 MHz range cannot be operated with this solution.

[0009] Against this background, the object of the present invention is to create a microwave-compatible inlay which is reliably shielded against microwaves on both sides without a separate underlying shielding element, and which also allows communication in both the HF / NFC range and the UHF range through the shielding.

[0010] This object is achieved by a microwave-compatible inlay according to the features of independent claim 1. Useful embodiments of such an inlay can be found in the subsequent dependent claims.

[0011] In this respect, a microwave-compatible inlay is provided, comprising an RFID chip, an antenna electrically or magnetically connected to the chip, and a first substrate arranged parallel to the surface with shielding surfaces. The RFID chip with the antenna is applied to the first substrate, and two adjacent shielding surfaces each have a gap between them. According to the invention, such a microwave-compatible inlay is characterized in that the shielding surfaces are arranged on the first substrate in such a way that they block any straight path through the shielding surfaces that runs exclusively along the gaps.

[0012] This is achieved because the gaps are designed in such a way that no microwave radiation is allowed to pass through the shielding surfaces of the first substrate, while the inlay can continue to transmit and receive. This represents an extreme case where microwave radiation can occur in the gaps and be coupled into the antenna in this area. However, this is counteracted by the shape and arrangement of the shielding surfaces blocking straight paths through these gaps. The inlay is therefore protected by this special form of shielding, but can itself transmit and receive across its entire spectrum, be it in the HF / NFC or UHF range. The inlay is protected in this arrangement and will not be damaged or destroyed in the microwave oven.

[0013] Preferably, the RFID chip, together with the antenna, can be applied directly to the first substrate on the side facing away from the shielding surfaces. Such an arrangement prevents short circuits between the RFID chip and the shielding surfaces and still ensures that the RFID chip can send and receive data. By arranging the RFID chip with its antenna directly on one side of the first substrate and the shielding surface on the opposite side of the same substrate layer, an extremely thin inlay is created, which as such can be used as a single layer. Such an extremely thin inlay offers little surface area against detachment, in particular peeling, from the adhesive surface, so that the mechanical and thermal durability is thereby significantly improved, for example during a washing process in a dishwasher.If a top layer can be dispensed with, only an adhesive layer is required as an adhesion promoter with the surface.

[0014] In an alternative embodiment, the RFID chip can be connected to an antenna that is applied to both sides of a second substrate, which is applied, preferably glued, to the first substrate on the side opposite the shielding surfaces. This allows the shielding surface and RFID chip with antenna to be manufactured separately and joined together in an additional work step. As a result, for example, the RFID chip or the shielding surface can be enclosed between the first and second substrates and thus additionally protected, or a double-layered substrate layer can be formed between these sides.

[0015] Direct attachment of the antenna to the shielding elements should be avoided to avoid creating short circuits.

[0016] The antenna can be applied to both sides of the second substrate, particularly in the case of HF / NFC antennas, and the shielding surfaces can be applied to the first substrate on the side facing away from the RFID chip and the antenna. Thus, using the second substrate, even double-layer antennas can be combined with the method according to the invention to form a still very thin inlay consisting of only two substrate layers.

[0017] In a specific embodiment, the shielding surfaces can be circular, oval, or a regular polygon, particularly a hexagon, so that each of these shielding surfaces is surrounded by six adjacent shielding surfaces. Alternatively, the shielding surfaces can also consist of freely formed contours. A circular design of the shielding surfaces is advantageous because it prevents sparks from corner to corner, which could ultimately destroy the inlay. Likewise, in principle, oval, regular polygonal, or even freely formed shielding surfaces can also be applied to the substrate. Especially with hexagonal shielding surfaces, it can be provided that they form a honeycomb pattern.Even in a honeycomb pattern, the shielding surfaces are arranged in such a way that the cutouts do not run in a straight line through a metal shield formed by the shielding surfaces, but rather that every straight path through the metal shield is blocked by a shielding surface. Consequently, even in such a modification, the RFID chip can be reliably protected from microwave radiation.

[0018] The shielding surfaces along a row can have a center-to-center spacing that is greater than the diameter of the individual shielding surfaces, while the spacing between one row and an adjacent row can be smaller than the diameter of the individual shielding surfaces. The proportional dimensions and the resulting nested rows ensure reliable shielding from interfering microwave radiation when the shielding surfaces are arranged regularly. At the same time, the RFID chip can communicate via its antenna between the shielding surfaces.

[0019] With some advantage, the gap between the shielding surfaces can be between 0.5 mm and 5 mm wide, and the shielding surfaces can occupy between 65 and 75 percent, preferably 70 percent, of the substrate area. The limited gap between the shielding surfaces ensures that the interfering microwave radiation is shielded. It is particularly advantageous if 70 percent of the substrate area is covered by the metallic shielding surfaces and 30 percent is free space.

[0020] The shielding surfaces can be made of copper or aluminum, preferably 8 to 10 µm thick aluminum, and applied to the first substrate by etching, punching, or gluing. In a further embodiment, the shielding surfaces can be printed with a conductive ink.

[0021] If the inlay is to be cast using an in-mold process or used without protective layers, such a designed inlay can be microwave-protected based on one or two layers. The microwave-protected inlay can also be embedded visibly or invisibly in the base or wall of a microwave-safe container or dish made of plastic, glass, or porcelain.

[0022] However, if the inlay is not intended to be used in its minimal state, in particular if a protective layer or print is to be applied, it can be specifically provided that the first substrate with the shielding surfaces, the applied RFID chip, and the antenna is jointly covered by a cover layer of printed or unprinted cast acrylate, with either the shielding surfaces or the RFID chip with the antenna facing the cover layer. The inlay is easily readable in both orientations, so it does not matter from which side the inlay is read. Furthermore, especially with a printed cover layer, an additional protective layer can be applied to protect the print.

[0023] With an adhesive layer applied to the first substrate, which can be protected against accidental adhesion by an easily removable backing paper, the inlay can be attached to an object such as a microwave cookware item.

[0024] The read / write area of ​​the microwave-safe RFID inlay can contain fixed information that is write-protected after initial programming, such as container ID, material and manufacturer, or weight, as well as variable information that must be reprogrammed repeatedly during a multiple-use cycle, such as the number of cycles, contents, and preparation information that supports scan-to-cook technology in the microwave ovens. The stored information can be programmed and read via HF / NFC-enabled smartphones or UHF readers and sent to the microwave ovens to adjust power, time, and movement patterns. It can also be designed for the microwave-safe RFID inlay on the microwave-safe container to send the necessary information for preparing the contents directly to a reading unit built into the microwave.The microwave-safe inlays can also be used in approved, microwave-safe disposable packaging and provide fixed and variable information for reading.

[0025] The invention described above is explained in more detail below using an exemplary embodiment.

[0026] It shows Fig. 1 shows a schematic plan view of an inlay according to the invention with an RFID chip and an antenna, which is applied to a first substrate with circular shielding surfaces, Fig. 2 an alternative embodiment of the inlay according to Fig. 1 with hexagonal, honeycomb-shaped shielding surfaces, Fig. 3 a smart label in a schematic, lateral cross-sectional view with an embodiment of an RFID inlay according to the invention, in which the different layers are shown with an antenna on one side of the first substrate, as well as Fig. 4 a smart label in a schematic, lateral cross-sectional view with an RFID inlay according to the invention, in which the different layers are shown, with an antenna on both sides of a second substrate.

[0027] Fig. 1 shows an inlay 1 which is prepared for use on a microwave cookware. For this purpose, the inlay 1 is attached to the microwave cookware on an underside facing away from the viewer via an adhesive layer 10. The inlay 1 comprises an RFID chip 2 for communication with a reader. The RFID chip 2 accomplishes this communication with the aid of an antenna 3. The RFID chip 2 and the antenna 3, together with a first substrate 4, which is preferably made of PET (polyethylene terephthalate), are combined to form the inlay 1 according to the invention. On the opposite side of the first substrate 4, round shielding surfaces 5 made of aluminum are arranged to shield against microwave radiation. The shielding surfaces 5 leave gaps between these shielding surfaces 5, wherein the shielding surfaces 5 are arranged spaced apart in staggered rows 6.The shielding surfaces 5 are thus arranged in a pattern in which the shielding surfaces 5 within a row 6 are spaced from each other by more than the diameter of a shielding surface 5 from center to center, while adjacent rows 6 are each spaced from each other by less than the diameter of a shielding surface 5, such that the shielding surfaces 5 of every other row 6 are arranged in alignment with each other. In this way, microwaves cannot penetrate through the inlay 1 with its shielding surfaces 5 along the gaps; the shielding surfaces 5 ultimately form a metal shield for the microwave radiation. HF / NFC and UHF communication, however, can still penetrate this metal shield, so that although microwave radiation does not damage the inlay 1, communication can still take place unhindered.

[0028] Fig. 2 shows an alternative embodiment of the inlay 1 formed from shielding surfaces 5. Here, the shielding surfaces 5 are designed as hexagons, forming a honeycomb pattern. The hexagons form alternating rows 6, which are arranged in an alternating layer sequence. The first substrate 4 has a uniform pattern of shielding surfaces 5 with gaps. The shielding surfaces 5 are arranged such that the gaps are not aligned in one direction. Rather, after a short distance, for example after passing a first shielding surface 5, an adjacent shielding surface 5 blocks further progression of a microwave beam, so that the beams repeatedly strike the shielding surfaces 5 arranged on the substrate 4. Coupling of the energy of the microwave beam into the inlay 1, i.e., into the RFID chip 2 via the antenna 3, can therefore be ruled out.

[0029] Fig. 3 shows the cross-section of a smart label 12 using an inlay 1 according to the invention. Shielding surfaces 5 and an RFID chip 2 with an antenna 3 are arranged directly on opposite sides of a first substrate 4, since the antenna is only applied to one side of the first substrate 4. The shielding surfaces 5 consist of punched and glued aluminum, or aluminum etched onto the first substrate 4. This special arrangement prevents a short circuit between the metallic shielding surfaces 5 and the antenna 3, yet the shielding allows RFID communication in both directions, and the shielding against microwave radiation is effective. The inlay 1 is combined with a cover layer 9 and a protective film 7 to form a smart label 12.Adhesive layers 10 are arranged between layers 7 and 9 and layers 9 and 4, as well as beneath the first substrate 4, to allow the smart label 12 to be adhered to a selected surface. A backing paper 11 protects the smart label from accidental adhesion.

[0030] Fig.4 shows the cross-section of a smart label 12 using the inlay 1 according to the invention. An antenna 3 and an RFID chip 2 are applied to a second substrate 8, wherein the antenna 3 is made of aluminum on both sides of the second substrate 8, for example by etching. This second substrate 8 is also applied with an adhesive layer 10 to a first substrate 4, which has shielding surfaces 5 on the side opposite the second substrate 8. The inlay 1 is also detachably connected to a carrier paper 11, for example a glassine paper, via an adhesive layer 10. A cover layer 9, preferably made of cast acrylic, is also glued over the inlay 1. Optionally, the entire assembly can be covered with a protective film 7 to protect a print applied to the cast acrylic.Adhesive layers 10 are provided between layers 11, 4, 8, 9, and 7 for bonding. These layers can be made of different adhesives depending on the application. This creates a smart label 12 that can transmit and receive in both directions through the shielding, but is immune to microwave radiation.

[0031] What is described above is a thin inlay that reliably shields its antenna and RFID chip against microwaves without an underlying shielding element, and also allows bidirectional communication through the shielding in both the HF / NFC range and the UHF range. LIST OF REFERENCE SYMBOLS 1 inlay 2 RFID chips 3 Antenna 4 first substrate 5 Shielding area 6 row 7 Protective film 8 second substrate 9 Top layer 10 adhesive layer 11 Backing paper 12 Smart Label QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 4 120 133 B1 [0002, 0006]

Claims

[1] Microwave-compatible inlay, comprising an RFID chip (2), an antenna (3) electrically or magnetically connected thereto and a first substrate (4) arranged parallel to the surface with shielding surfaces (5), wherein the RFID chip (2) with the antenna (3) is applied to the first substrate (4) and two adjacent shielding surfaces (5) each have a space between them, characterized by that the shielding surfaces (5) on the first substrate (4) are arranged in such a way that they block any straight path through the shielding surfaces (5) running exclusively along the intermediate spaces. [2] Inlay according to claim 1, characterized by that the RFID chip (2) together with the antenna (3) is applied directly to the first substrate (4) on its side facing away from the shielding surfaces (5). [3] Inlay according to claim 1, characterized bythat the RFID chip (2) is applied, preferably glued, together with the antenna (3) to a second substrate (8) and this is applied to the first substrate (4) on the side opposite the shielding surfaces. [4] Inlay according to claim 3, characterized by that the antenna (3) is applied to both sides of the second substrate and the shielding surfaces (5) are applied to the first substrate (4) on its side facing away from the RFID chip (2) and the antenna (3). [5] Inlay according to one of the preceding claims, characterized by that the shielding surfaces (5) are circular, oval or designed as a regular polygon, in particular a hexagon, so that each shielding surface (5) is surrounded by six adjacent shielding surfaces (5) in staggered rows (6). [6] Inlay according to claim 5, characterized bythat the shielding surfaces (5) along a row (6) have a distance from center to center that is greater than the diameter of the individual shielding surfaces (5), while the distance of one row (6) to an adjacent row (6) is smaller than the diameter of the individual shielding surfaces (5). [7] Inlay according to one of claims 1 to 4, characterized by that the shielding surfaces (5) consist of freely formed contours. [8] Inlay according to one of the preceding claims, characterized by that adjacent shielding surfaces (5) enclose a gap of 0.5 to 5 mm wide between them. [9] Inlay according to one of the preceding claims, characterized by that the shielding surfaces (5) cover between 65 and 75 percent, preferably 70 percent of the surface of the first substrate (4). [10] Inlay according to one of the preceding claims, characterized bythat the shielding surfaces (5) made of copper or aluminum, preferably of 8 to 10 µm thick aluminum, are applied to the first substrate (4) by etching or by punching and gluing. [11] Inlay according to one of claims 1 to 9, characterized by that the shielding surfaces (5) and / or the antenna (3) are printed from a conductive ink. [12] Inlay according to any preceding claim, characterized by that the first substrate (4) with the shielding surfaces (5), the applied RFID chip (2) and the antenna (3) is covered together by a cover layer (9) made of printed or unprinted cast acrylate, wherein either the shielding surfaces (5) or the RFID chip (2) with the antenna (3) face the cover layer (9). [13] Inlay according to one of the preceding claims, characterized bythat the first substrate (4) is assigned an adhesive layer (10) which is prepared for attachment to a base, preferably a microwave cookware item. [14] Inlay according to one of claims 1 to 13, which is incorporated in a material-to-material, visible or invisibly, into the bottom or wall of a microwave-compatible container or crockery item made of plastic, glass or porcelain. [15] Inlay according to one of the preceding claims, characterized by that the RFID chip is assigned a read / write memory to which control commands for controlling a microwave oven are assigned.

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