Radio frequency identification tag assembly and identifiable object to which the radio frequency identification tag assembly is attached

Abstract

Provided are a radio frequency identification tag assembly and an identifiable object to which the radio frequency identification tag assembly is attached. The radio frequency identification tag assembly comprises a metal plate having an upper surface and a lower surface; a radiating element, the radiating element comprising a tag housing arranged along one side edge of the upper surface of the metal plate, the tag housing comprising an IC chip, an antenna and a circuit board electrically connecting the IC chip and the antenna inside the tag housing, wherein the antenna is made of metal, the antenna has a first segment and a second segment parallel to the upper surface of the metal plate, the first segment has a first spacing from the upper surface of the metal plate, and the first segment has a second spacing from the second segment, and the upper surface of the metal plate is at an angle to the plane in which the antenna lies.

Description

Technical Field

[0001] This invention relates to the field of radio frequency identification, and more specifically to a tag assembly for radio frequency identification and an identifiable object with the radio frequency identification (RFID) tag assembly attached thereto. Background Technology

[0002] In recent years, dedicated RFID tags with various forms and special encapsulations have been widely used in various technical fields for the movement, installation, management, and maintenance of indoor and outdoor assets and equipment. These tags are categorized based on application environment and tag attachment conditions, including size, attachment method, selection of special materials, and required identification performance. In particular, UHF band RFID tags utilize backscattering, meaning their performance is significantly affected not only by reflection, attenuation, absorption, and diffraction from the surrounding radio wave environment, but also by the material and location of the attached object and the tagging conditions.

[0003] The drastic drop in recognition rate caused by polarization inconsistencies (circular vs. linear polarization) and the height difference between the reader antenna and the tag mounting height is a major factor determining the success rate of an RFID system. Typically, the maximum radiation gain and readable distance of an RFID tag are formed in a direction perpendicular to the surface of the attached object. Due to the characteristics of RFID application environments, when the tag attachment position and reader antenna height are inconsistent, or when the tag is read in a direction offset to the left or right of the tag attachment position, the radar cross section (RCS) cross-sectional area decreases, leading to a sharp reduction in tag recognition distance. In practical environments such as multi-layer shelving and asset management, external facility asset management with relatively high tag attachment heights, and item identification in automated warehouses, this reduced tag recognition distance is considered a risk factor that reduces the reliability of RFID systems and affects the stability of integrated systems. Therefore, as the application of RFID technology expands across various industries, specialized RFID tag technology is needed to prevent tag performance degradation due to varying tag attachment heights and to consider the operational processes on-site. Summary of the Invention

[0004] The present invention aims to overcome the above-mentioned and / or other problems in the prior art. With the RFID tag assembly provided by the present invention, even when identified by a user's RFID reader at a position higher or lower than the RFID tag antenna, or at a left / right offset, identification can be easily achieved by changing the attachment direction of the same tag. This helps to solve the problem of tag performance deviation or low tag performance due to different tag placement heights.

[0005] According to a first aspect of the present invention, a radio frequency identification (RFID) tag assembly is provided, wherein the RFID tag assembly comprises: a metal plate having an upper surface and a lower surface; a radiating element including a tag housing arranged along one side of the upper surface of the metal plate, the tag housing including an IC chip, an antenna, and a circuit board electrically connecting the IC chip and the antenna, wherein the antenna is made of metal and has a first segment and a second segment parallel to the upper surface of the metal plate, the first segment having a first distance from the upper surface of the metal plate and a second distance from the first segment to the second segment, and the upper surface of the metal plate forming an angle with the plane containing the antenna.

[0006] Preferably, the IC chip operates in the UHF band.

[0007] Preferably, one end of the first segment of the antenna is connected to one end of the second segment via a conductor.

[0008] Preferably, the conductor is the bend between the first segment and the second segment of the antenna, and the first segment, the second segment, and the bend integrally constitute the antenna.

[0009] Preferably, the conductor is a wire disposed within the housing and separate from the antenna.

[0010] Preferably, the plane in which the antenna is located is perpendicular to the upper surface of the metal plate.

[0011] Preferably, the metal plate serves as the ground plane for the RFID tag assembly.

[0012] Preferably, the RFID tag assembly is configured by attaching the lower surface of the metal plate to the object to be identified.

[0013] Preferably, the housing has a mounting slot for embedding the antenna and the circuit board.

[0014] Preferably, the mounting slot includes: a plurality of recesses for embedding an antenna, wherein the plurality of recesses include a plurality of horizontal slots and a plurality of vertical slots, the plurality of horizontal slots including a first horizontal slot and a second horizontal slot, the first horizontal slot being configured to embed a first segment of the antenna, the second horizontal slot being configured to embed a second segment of the antenna, and the vertical slot being configured to embed the conductor; and a plurality of receiving spaces, each of the plurality of receiving spaces being used to receive the circuit board.

[0015] Preferably, each of the plurality of horizontal grooves intersects at least one of the plurality of receiving spaces, the plurality of horizontal grooves are parallel to the upper surface of the metal plate, the plurality of horizontal grooves are at unequal distances from the upper surface of the metal plate, and the plurality of receiving spaces are at multiple distances from the vertical groove.

[0016] Preferably, the first segment of the antenna extends into the third horizontal slot of the plurality of horizontal slots, and / or the second segment of the antenna extends into the fourth horizontal slot of the plurality of horizontal slots.

[0017] Preferably, the first horizontal slot is configured to accommodate a first segment of the antenna of different lengths, and the second horizontal slot is configured to accommodate a second segment of the antenna of different lengths.

[0018] Preferably, the label housing is fixed to the metal plate by a positioning mechanism so that the lower surface of the label housing remains horizontal relative to the upper surface of the metal plate.

[0019] Preferably, the positioning mechanism includes a threaded member for securing the label housing to the metal plate and a grid-shaped fixing member located on the upper surface of the metal plate.

[0020] Preferably, the metal plate is embossed, stamped, laser-processed, or printed with visual identifiers.

[0021] Preferably, the direction of the maximum radiation gain of the RFID tag assembly is tilted from the direction perpendicular to the metal plate.

[0022] Furthermore, the RFID tag assembly of the present invention is designed to use thin metal wires as antennas. This wire-shaped tag radiating platform, due to the inherent flexibility and thinness of the material, offers the following advantages: it simplifies impedance matching when using the 3D tag shape for RFID tag antennas and enables efficient tag design within a limited space. Additionally, the flexible wire material allows for easy modification of the RFID tag's electrical design during center frequency control and electrical matching optimization through simple variations in the wire platform length and control of the spacing between the metal wires. To realize the RFID tag radiator, such 3D metal wires are placed inside a high-temperature resistant plastic component and formed through ultrasonic welding or injection molding. To electrically connect the metal wires, which serve as the conductive radiating medium, to the IC chip, a small PCB block is constructed and the IC chip is bonded therein. Metal wires are bonded to both sides of the small PCB block to construct the metal wire radiator. The three-dimensional tag radiator structure constructed as described above is combined with an additional metal plate of a certain area below; the tag radiator is fixed along the side of the metal plate. Therefore, the relative position of the tag radiator and the metal plate can be used as an important design parameter to determine the radiation gain direction of the tag antenna.

[0023] Furthermore, as described above, the metal plate and the tag radiator are constructed separately, allowing for embossing and stamping on the metal plate surface. This metal plate embossing / stamping process provides a semi-permanent, intuitive visual identification and differentiation capability, maintaining compatibility with industries that traditionally require this type of processing while also offering the advantage of incorporating RFID tags.

[0024] According to a second aspect of the invention, an identifiable object is provided, the identifiable object having a radio frequency identification tag assembly as described in any of the preceding claims attached thereto.

[0025] Preferably, the identifiable objects include facility assets and shelving.

[0026] Other features and aspects will become clear from the following detailed description, accompanying drawings, and claims. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0028] Figure 1A schematic diagram is shown showing the radiation area based on the height difference of the tag attachment position when identifying conventional RFID tags 110 and 120 using a portable reader.

[0029] Figure 2 The illustration shows the radiation areas of RFID tags 210 and 220 according to the height difference of the tag attachment position, which are identified by an RFID reader according to an embodiment of the present invention.

[0030] Figure 3 A perspective view of an RFID tag assembly with variable main radiation directionality according to an embodiment of the present invention is shown.

[0031] Figure 4 A schematic exploded view of an RFID tag assembly according to an embodiment of the present invention is shown.

[0032] Figure 5 An exploded perspective view of a radiating element according to an embodiment of the present invention is shown.

[0033] Figure 6a and Figure 6b A front view of a metal wire installed inside a tag housing as a tag antenna, according to an embodiment of the present invention, is shown.

[0034] Figure 7 The Smith chart shows the simulation results of the impedance of the radiating element, which varies with the distance between the PCB and the conductor connected side in the first segment according to an embodiment of the present invention.

[0035] Figure 8 The installation orientation of the RFID tag components on the attached object is shown schematically at different relative positions.

[0036] Figures 9a-9d A front view is shown illustrating the alteration of the structure of the first and second segments using a tag antenna according to an alternative embodiment of the present invention.

[0037] Figure 10 A diagram illustrating the radiation pattern of a tag antenna with variable main radiation directivity based on the maximum radiation gain of the azimuth angle according to an embodiment of the present invention is shown.

[0038] Figure 11 The results of measuring the long-range identification distance of an RFID tag antenna with variable main radiation directivity using a tag antenna according to an embodiment of the present invention in the UHF RFID band are shown. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the present invention will be described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure will be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0042] The following describes specific embodiments of the present invention. It should be noted that, in order to provide a concise description, this specification cannot exhaustively describe all features of the actual embodiments. It should be understood that, in the actual implementation of any embodiment, just as in any engineering or design project, various specific decisions are often made to achieve the developer's specific goals and to meet system-related or business-related constraints, and this can change from one embodiment to another. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, some design, manufacturing, or production modifications based on the technical content disclosed herein are merely conventional technical means and should not be construed as insufficient content of this disclosure.

[0043] Unless otherwise defined, the technical or scientific terms used in the claims and description shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in the patent application description and claims of this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms mean that the element or object preceding "comprising" or "including" encompasses the element or object listed following "comprising" or "including" and its equivalents, and do not exclude other elements or objects. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0044] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions. Similarly, unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0045] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0046] The RFID tag proposed in this invention can be attached to a specific object or asset. The far-field radiation direction of the tag is selectively biased towards the antenna direction of a fixed / handheld reader, maximizing the line-of-sight identifiable distance of the RFID tag. Preferably, the RFID tag of this invention is used in the UHF band.

[0047] Compared to AIDC (Automatic Identification Data Tracking), passive RFID tags offer the advantage of being able to identify multiple tags in batches over long distances using non-contact radio frequency (RF) methods. However, optimal long-range identification with RFID tags requires a stable environment free from radio wave reflection, diffraction, attenuation / absorption between the RFID tag and the reader antenna, as well as alignment of the polarization directions of the reader antenna and the tag antenna, and maintaining the tag identification direction within the line-of-sight direction.

[0048] Due to the characteristics of radio wave radiation and the fundamental backscattering property of RFID, the reflection or diffraction of RF radio waves through the conductive medium in RFID application environments leads to multipath formation between the RFID tag antenna and the reader antenna. The radio waves incident on the tag antenna through these multipaths are composed of superimposed radio waves of different phases. In particular, the destructive interference between the tag antenna and the reader antenna due to phase differences is the fundamental reason for the sharp reduction in RFID tag identification distance and the decreased stability of the RFID system. Furthermore, in long-range tag identification environments, proximity to high-loss materials such as high-dielectric materials can reduce RF wave signal strength and alter the tag's RF center frequency, hindering the construction of an optimal marking environment.

[0049] Furthermore, in field application environments where the marking pattern of RFID tags does not align with the optimal polarization direction of the reader antenna, the reader antenna typically uses circular polarization (CP) to mitigate the polarization inconsistency problem. In other words, most commercially available specialized RFID tags generally exhibit linear polarization (LP) characteristics, but the issue of inconsistent marking in the vertical / horizontal directions is improved by using circular polarization in the reader antenna. However, due to the polarization mismatch between the linearly polarized RFID tag and the circularly polarized reader antenna, a 3dB power loss occurs, resulting in a decrease in long-range tag identification performance.

[0050] Furthermore, due to the recent expansion of RFID technology applications across various industries, there has been an increase in applications where tags attached to warehouse shelves are placed at higher elevations or require marking at an angle relative to the horizontal plane. Typically, the electrical performance of RFID tags is significantly affected by factors such as the material characteristics of the attached object and its attachment location, interference from electromagnetic waves in the application environment, the polarization characteristics of the tag and reader antennas, and tag degradation due to prolonged exposure to high temperatures. In particular, RFID tags attached to objects mounted on high shelves 230 or similar structures, or tags 110 attached to external infrastructure assets at a higher elevation, have a height discrepancy with the antenna of the user's fixed / portable reader 100. This height discrepancy causes the reader antenna to identify the tag at an angle relative to the tag. For example, in... Figure 1In this context, the radiation pattern 115 of tag 110 attached to an object at a higher height and the radiation pattern 125 of tag 120 attached to an object at a lower height have a height difference from the radiation pattern 105 of the reader 100's antenna, causing the reader 100 to identify tags at an angle tilted relative to tags 110 and 120. When identifying RFID tags at an angle, the radar cross section (RCS) of the tag decreases proportionally with the tilt angle, resulting in a sharp decrease in the long-range tag identification distance. Furthermore, the long-range radiation gain characteristics of a typical tag are distributed at a certain angle, and the radiation gain distribution of the tag reaches its maximum value relative to the vertical direction of the tag's front. Such a tag radiation gain distribution exhibits a sharp decrease in radiation gain characteristics at the tilt angle. Although it varies depending on the size of the tag antenna, the size of the metal attachment object, and the design of the RFID tag antenna, the half-power radiation gain angle (3dB radiation angle) of a typical metal tag antenna is formed at approximately 30° to 60°. That is, when a typical metal tag antenna is attached to a high load on a shelf or to a high facility asset, ground users will lose a considerable amount of radiated power when identifying the antenna using a portable reader 100. This trend means that the greater the height difference, the lower the tag recognition performance.

[0051] Figure 1 A schematic diagram is shown showing the radiation area based on the height difference of the tag attachment position when using a portable reader 100 to identify conventional RFID tags 110, 120.

[0052] Typically, the maximum radiation gain area is formed in a direction perpendicular to the object 140 to which the conventional RFID tags 110 and 120 are attached, and the maximum identification distance of the reader antenna is achieved in the same direction in an interference-free environment. However, because the radiation directions of the RFID tags 110 and 120 and the reader antenna 100 are finite, identifying tags in a direction tilted relative to the front of the attached tag results in considerable power loss. In such applications, the tilt angle of the reader antenna significantly reduces the tag's RCS cross-sectional area and drastically reduces the signal strength received by the reader antenna. In particular, the reduced tag identification distance and lower tag identification ratio caused by a high tag placement height on external facility assets or a large deviation of the tag attachment height on indoor loading racks 130 from the parallel height of the RFID reader antenna 100 are important factors in maintaining the stability of the RFID system.

[0053] To overcome the drawbacks in the aforementioned application environments, a method has been proposed that involves inserting an additional mechanism into the attached object to mechanically adjust the direction of the RFID tag's maximum radiation gain toward the reader's antenna. However, this method of mechanically adjusting the radiation pointing angle to orient tags attached to high infrastructure assets toward the ground incurs considerable additional costs for implementing RFID tags and makes it difficult to quantitatively adjust the orientation based on tag height. Furthermore, in application environments with varying heights, RFID tags are identified by increasing the antenna height on autonomous robots moving along predetermined paths or by utilizing mobile RFID devices mounted on unmanned aerial vehicles (UAVs) that function as flying objects in space.

[0054] This invention relates to passive RFID tags that maximize the electrical reliability of tags used in RFID systems by controlling the long-range readable directionality of RFID tags to more stably identify special tags attached to tall facility assets and tall shelving units. To achieve the above objectives, this invention aims to overcome the degradation and stripping of the conductive medium in existing RFID tags by utilizing thin metal wires with a three-dimensional (3D) structure, and by providing an additional self-contained metal plate, enabling the RFID radiating structure to be widely used on both metallic and non-metallic objects.

[0055] Typically, the maximum long-range radiation direction of RFID tag antennas in the UHF band is affected in various ways depending on the tag design, attachment ground, relative tag position, and tag topology variations (planar or three-dimensional). RFID tags used in RFID systems typically achieve maximum readable identification distance in the tag's attachment direction when the maximum radiation gain of the tag antenna is aligned with the vertical frontal direction of the attached object, thus aligning the reader antenna with the polarization. As mentioned above, typical RFID tags have the following characteristic: when the RFID tag's attachment height is higher or lower than the reader's antenna, the reader antenna deviates from the tag antenna's maximum readable identification distance, resulting in a sharp decrease in tag identification distance. In particular, because external assets in transportation and power industries, or goods loaded on shelves in large warehouses, are positioned at a high height relative to the reader user on the ground, the maximum tag cross-section (RCS radar cross-section) over the line of sight cannot be obtained. In this situation, in order to mechanically orient the tag's radiation gain direction toward the ground, auxiliary tools can be used or the tag can be set at an angle when it is attached. However, it is difficult to adjust the precise angle according to the height deviation, and there will be additional setup costs.

[0056] Figure 2The illustration schematically demonstrates the advantages of radiation areas varying according to the height of the tag attachment position when using an RFID reader to identify an RFID tag 210 according to an embodiment of the present invention. Generally, the alignment of the directional radiation direction of the RFID tag and reader antenna with the polarization of the RFID reader is a factor determining RFID identification distance performance. In particular, the identification distance performance of the RFID tag can be significantly improved when the directional radiation angle of the RFID tag 210, positioned at a height relative to the RFID reader user (e.g., on an object 240 on a shelf 230), aligns with the radiation pattern 205 angle of the user's reader antenna 200. Tags with such variable main radiation directionality offer the advantage that identification can be easily achieved even when the tag is identified by the user's RFID reader at a position that is higher or lower than the RFID tag antenna or tilted left / right, by changing the same tag attachment direction, thereby fundamentally solving the problem of tag performance deviation or low tag performance depending on the height difference of the tag placement position.

[0057] For the tag radiating element used in this invention, existing labels, PCBs, and ceramic materials limit the durability of RFID tags due to degradation and peeling under prolonged high-temperature environments. As a fundamental solution, a thin metal wire is designed. This wire-shaped tag radiating platform offers advantages due to the material's flexibility and thinness: it simplifies impedance matching for RFID tag antennas by providing a 3D tag shape and enables efficient tag design within a limited space. Furthermore, the flexible wire material allows for easy modification of the RFID tag's electrical design during center frequency control and electrical matching optimization through simple variations in the wire platform length and spacing between the metal wires. To realize the RFID tag radiator, such a 3D metal wire is placed inside a high-temperature resistant plastic component and formed through ultrasonic welding or injection molding. To electrically connect the metal wire, which serves as the conductive radiating medium, to the IC chip, a small PCB block is constructed and the IC chip is bonded within it. The metal wire is then bonded to both sides of the small PCB block to construct the metal wire radiator. The three-dimensional tag radiator structure constructed as described above is combined with another metal plate of a certain area below it; the tag radiator is fixed along the side of the metal plate. Therefore, the relative position of the tag radiator and the metal plate can be used as an important design parameter to determine the radiation gain direction of the tag antenna.

[0058] Furthermore, as described above, the metal plate and the tag radiator are constructed separately, allowing for embossing and stamping on the metal plate surface. This metal plate embossing / stamping operation provides users with semi-permanent, intuitive visual identification and differentiation, maintaining compatibility with industries that traditionally require this type of processing while also offering the advantage of introducing RFID tags. In particular, performing this embossing / stamping operation on existing nameplate-type tags directly or indirectly damages the tag, making it impossible.

[0059] Typical UHF band RFID tags are designed for use with both metallic and non-metallic attachment materials. This is achieved by having a finite metallic ground plane and maximizing radiation gain in a direction perpendicular to the attached object. When the tag is attached to a metallic material, the long-range radiation gain and the directional accuracy of the tag's radiation pattern are affected by variations in the metal plate within the tag structure and its attachment position relative to the metal.

[0060] In this invention, in order to easily realize the three-dimensional shape of the label and enhance the durability and reliability of the label in high temperature and low temperature cycling environments and ultra-high temperature environments, conductive metal wires are used to construct the label radiating element instead of existing PCB materials or bulk ceramic materials.

[0061] Figure 3 A perspective view of an RFID tag assembly 300 with variable main radiation directionality according to an embodiment of the present invention is shown. Figure 4 A schematic exploded view of an RFID tag assembly 300 according to an embodiment of the present invention is shown. Figure 5 An exploded perspective view of the radiating element 320 according to an embodiment of the present invention is shown, and Figure 6a and Figure 6b A front view of a metal wire installed inside tag housings 500a and 500b, serving as a tag antenna 510, according to an embodiment of the present invention, is shown, wherein... Figure 6a The diagram shows the configuration of PCB 530, which is positioned in the first segment 520 at a distance d1 from the side connected to conductor 550. Figure 6b The positions 610a, 610b, 610c, and 610d of the PCB 530, which can be varied to change the impedance of the radiating element 320, are shown. (See reference...) Figures 3-6b The following explanation is provided.

[0062] Figure 3A perspective view of an RFID tag assembly 300 with variable main radiation directionality according to an embodiment of the present invention is shown. The RFID tag assembly 300 may include a radiating element 320 and a metal plate 330. The radiating element 320 may be arranged along the side of the upper surface of the metal plate 330. The metal plate 330 may serve as a ground plane for the RFID tag assembly 300. A mounting mechanism 310 enables the lower surface of the metal plate 330 to be attached to an object to be identified (e.g., an item on a shelf or an asset facility). In one embodiment, the mounting mechanism 310 may be a threaded component and may be located on both sides of the metal plate 330, but those skilled in the art can conceive of any other mounting mechanism, mounting location, or attachment method, such as adhesive. Further expansion of the application range of RFID tags can be provided by embossing / stamping 340 on the metal plate 330, which is intuitively recognizable to the user and semi-permanently usable. In the automotive or machinery industries, various identifiers have long been processed on the surface of aluminum or copper plates by mechanical embossing / stamping for the identification of equipment and assets. However, in the case of RFID tags, it is difficult to find commercially available tags that can be stamped / embossed on the surface, and such physical stamping / embossing operations on some RFID tags damage the tag's functionality. In the tag assembly 300 proposed in this invention, a radiating element 320 and a metal plate 330 capable of embossing / stamping 340 can be separately constructed, and then the two are combined. Furthermore, such a metal plate 330 can be constructed from different materials (such as aluminum, stainless steel) in different sizes and thicknesses.

[0063] Figure 4 A schematic exploded view of an RFID tag assembly according to an embodiment of the present invention is shown. The metal plate 330 can be of any size and thickness and can be stamped / embossed 340. The configuration of the equipment for implementing the stamping / embossing process can be considered to select the material, thickness, and size of the metal plate 330, and the electrical characteristics of the tag antenna of the RFID tag assembly can be selected independently of the material, thickness, and size of the metal plate 330. Depending on the user's environment and needs, stamping / embossing, laser processing, and printing in paint form can be selectively performed on the surface of the metal plate 330.

[0064] The radiating element 320 can be mounted on the upper surface of the metal plate 330 by various fixing mechanisms. Figure 4A fixing mechanism for mounting a radiating element 320 to the upper surface of a metal plate 330 is shown. This mechanism may include a threaded member 410 and a grid-shaped fastener 420. A threaded portion for receiving the threaded member 410 may be configured to protrude from the upper surface of the metal plate 330 to ensure the lower surface of the metal plate 330 is flat when mounted to the attachment object. The grid-shaped fastener 420 may protrude from the metal plate 330 to enhance the connection strength with the radiating element 320. Mechanically connecting the radiating element 320 and the metal plate 330 via the threaded member 410 increases the connection strength, and maintaining a constant spacing between the lower surface of the radiating element 320 and the upper surface of the metal plate 330 via the grid-shaped fastener 420 keeps the attachment surface flat and stable when attaching the RFID tag assembly 300 to the facility asset. Those skilled in the art will recognize that one or both may be selected for mounting, or any other mounting structure may be used. The radiating element 320 may be mounted such that the tag antenna 510 contained therein (e.g., Figure 5 The plane containing the tag antenna 510 forms an angle with the upper surface of the metal plate 330. Preferably, this angle can be between 30° and 150°. More preferably, the plane containing the tag antenna 510 can be perpendicular to the upper surface of the metal plate 330. In this way, the maximum radiation gain of the RFID tag assembly 300 may not be in a direction perpendicular to the surface of the metal plate 330 (and therefore the surface to which it is attached).

[0065] Figure 5 An exploded perspective view of a radiating element 320 according to an embodiment of the present invention is shown. The radiating element 320 may include a thin metal wire in a three-dimensional shape serving as a tag antenna 510, which may be mounted inside tag housings 500a and 500b. To improve the high-temperature reliability and durability of the tag antenna 510, the metal used for the tag antenna 510 may be various metals that can be made into wires, such as copper, iron, aluminum, gold, or alloys. Tag housings 500a and 500b may be formed of a high-temperature resistant plastic and tightly joined together by ultrasonic welding after separate construction. The high-temperature resistant plastic may be epoxy resin. Other methods for tightly joining tag housings 500a and 500b can also be conceived by those skilled in the art. An IC chip may also be included within the tag housing 320. A PCB 530 may be used as a connection medium to connect the tag antenna 510 to the IC chip. The PCB 530 may be configured to host the IC chip therein and has electrodes on both sides for hosting the tag antenna 510. The tag antenna 510 can be bonded to the PCB 530 by soldering, and other bonding methods can be conceived by those skilled in the art.

[0066] According to one embodiment of the present invention, the tag antenna 510 may include a first segment 520 and a second segment 540, and a PCB 530 may be positioned on the first segment 520 of the tag antenna 510. The first segment 520 of the tag antenna 510 may be connected to the second segment 540 on one side by a conductor 550, and may be disconnected from the second segment 540 on the other side of the first segment 520 (i.e., the side opposite to the conductor 550), thereby the first segment 520 and the second segment 540 may be coupled to each other on one side.

[0067] Conductor 550 may be a bent portion integrally formed with the first segment 520 and the second segment 540 to constitute the tag antenna 510. Alternatively, conductor 550 may be a separate wire fixed inside the tag housing 500b and connected to the first segment 520 and the second segment 540 after installation. A first gap h1 may be present between the first segment 520 and the upper surface of the metal plate 330, and a second gap h2 may be present between the first segment 520 and the second segment 540 (e.g., ...). Figure 6a (As shown).

[0068] Furthermore, the tag housings 500a and 500b may have mounting slots inside to embed the tag antenna 510 and PCB 530, so that the tag antenna 510 can be stably fixed inside the tag housings 500a and 500b and maintained in an effective conjugate impedance matching state. The mounting slots may include multiple recesses for accommodating the tag antenna 510 and multiple accommodating spaces for accommodating the PCB 530 to provide multiple different paths to increase the effective resonant length of the tag antenna 510 within a limited area. Such multiple paths can provide the advantage that, in controlling the center frequency of the radiating element 320 or in the manufacturing process of the tag assembly 300, performance deviations can be easily improved to achieve the desired performance of the radiating element 320 without significant changes to existing materials or designs.

[0069] In one embodiment, the plurality of grooves may include a plurality of horizontal grooves and a plurality of vertical grooves, including a first horizontal groove 560a for accommodating a first segment 520 of a tag antenna 510, a second horizontal groove 560b for accommodating a second segment 540, and a vertical groove 560c for accommodating a conductor 550.

[0070] Figure 6a and Figure 6b A front view of a metal wire installed inside tag housings 500a and 500b, serving as a tag antenna 510, according to an embodiment of the present invention, is shown, wherein... Figure 6a The diagram shows the configuration of PCB 530, which is positioned in the first segment 520 at a distance d1 from the side connected to conductor 550. Figure 6bThe positions 610a, 610b, 610c, and 610d of the PCB 530 that can be changed to alter the impedance of the radiating element 320 are shown. These positions are shown only as examples, and those skilled in the art can conceive of the positions of the PCB 530 as needed.

[0071] The RFID tag assembly 300 including the tag antenna 510 proposed in this invention may include the following important design parameters: in a three-dimensional structure, the distance d1 between the PCB 530 with the IC chip and the side connected to the antenna 510 and conductor 550; the distance h1 between the first segment 520 of the tag antenna 510 and the upper surface of the metal plate 330; the distance h2 between the first segment 520 and the second segment 540 of the tag antenna 510; and the length of the antenna 510 (including the first segment 520, the second segment 540, and the conductor 550) that enables control over the effective resonant length of the tag antenna 510. These important design parameters provide the following advantages: to achieve complex impedance matching for IC chips in various UHF bands, electrical matching can be easily made variable within the same structure without changing the material and appearance of existing tags by optimizing one or more design parameters of the RFID tag assembly 300. Specifically, the relative positional change of the PCB 530 incorporating the RFID IC chip can serve as a design parameter that maximizes the impact on the impedance variation of a specific IC chip, providing design compatibility for various commonly used IC chips without altering the existing tag housing structure. This is achieved by adjusting the distance between the PCB 530 and the conductor 550 (i.e., Figure 6a The d1 in the figure can control the impedance matching and center resonant frequency of the tag antenna.

[0072] Figure 7 The Smith chart illustrates the distance between the PCB 530 and the conductor 550 connected to each other in the first segment 520 according to an embodiment of the present invention (i.e., Figure 6aThe simulation results show the impedance of the radiating element changing with the variation of d1). As an example, the simulation results employ a structure where a conductor 550 is formed on one side by folding a metal wire vertically, such that the first segment 520 and the second segment 540 are short-circuited via the conductor 550, and disconnected on the opposite side, achieving effective impedance matching of the complex impedance of a typical IC chip. Specifically, on the right side of the tag antenna 510, the first segment 520 and the second segment 540 can be short-circuited via the conductor 550 in the side mounting slot 560c, and to achieve effective impedance control and appropriate tag radiation gain, on the left side of the tag antenna 510, the first segment 520 and the second segment 540 can be separated by a distance h2, and the first segment 520 and the upper surface of the metal plate 330 can be separated by a distance h1. All the above design parameters are designed to effectively control the center frequency and impedance matching of the tag assembly 300, and this one-sided short-circuited structure and the PCB 530 disposed in the receiving space can serve as important design parameters for controlling the impedance matching of the tag assembly 300.

[0073] like Figure 7 As shown in the Smith chart, the imaginary part of the IC chip's impedance is illustrated as d1 gradually decreases from 13mm to 3mm in 2.5mm increments. When d1 is 13.0mm, the imaginary part of the complex impedance is +282 Ohms; when d1 is 10.5mm, the imaginary part is +227 Ohms; when d1 is 8.0mm, the imaginary part is +194 Ohms; when d1 is 5.5mm, the imaginary part is +174 Ohms; and when d1 is 3.0mm, the imaginary part is +158 Ohms. The impedance of commonly used UHF band IC chips typically falls within these ranges, and general impedance matching for commonly used UHF band IC chips can be achieved by utilizing the variable positions of the PCB 530.

[0074] Furthermore, a gap h1 can be formed between the first segment 520 of the tag antenna 510 and the upper surface of the metal plate 330. Such coupling can affect tag matching and long-range radiation pattern directivity.

[0075] The first segment 520 of the tag antenna 510 can be coupled to the metal plate 330 in an asymmetrical structure, and the plane on which the tag antenna 510 is located can be at an angle (preferably perpendicular) relative to the upper surface of the metal plate 330, thereby causing the long-range radiation pointing angle of the tag assembly 300 to be deflected in a specific direction.

[0076] Figure 8 The illustration shows the installation orientation of RFID tag components on attached objects at different relative positions.

[0077] The radiating element 320, including the tag antenna 510, can be mounted onto the metal plate 330 via a fixing mechanism. The resulting tag assembly 300 can have a symmetrical structure in the left-right direction and an asymmetrical structure in the top-bottom direction. In this asymmetrical structure, the maximum radiation gain of the radiating element 320 can be shifted from a direction perpendicular to the surface of the metal plate 330 towards the direction of the radiating element 320. This feature allows the maximum radiation gain direction of the tag assembly 300 to tilt downwards when the radiating element 320 is positioned along the lower edge of the metal plate 330 in a higher facility asset 810, and conversely, when the radiating element 320 is positioned along the upper edge of the metal plate 330 in a lower facility asset 820, the maximum radiation gain of the tag assembly 300 can tilt upwards, thereby increasing the readable identification distance of the tag assembly. When the radiating element 320 is positioned along the right edge of the metal plate 330 in the case of facility asset 830 on the relative left, the maximum radiating gain of the tag assembly 300 can be tilted to the right, and when the radiating element 320 is positioned along the left edge of the metal plate 330 in the case of facility asset 840 on the relative right, the maximum radiating gain of the tag assembly 300 can be tilted to the left, thereby increasing the readable recognition distance of the tag assembly.

[0078] Figures 9a-9d A front view is shown illustrating the alteration of the structure of the first segment 520 and the second segment 540 using a tag antenna 510 according to an alternative embodiment of the invention. According to one embodiment of the invention, a PCB 530 may be located within the first segment 520 of the tag antenna 510, and may be short-circuited on one side of the tag antenna 510 and disconnected on the opposite side. Those skilled in the art will recognize that by altering the above-described structure of the tag antenna 510 to any shape, it can be used as a variable for adjusting the center frequency of the radiating element 320 and achieving optimal impedance matching for individual IC chips. Figure 9a The diagram shows a basic structure in which the PCB 530 can be located near one side of the first segment 520 of the tag antenna 510. Figure 9b The first segment 520 and the second segment 540 of the tag antenna 510 are shown in the figure. Figure 9a Compared to deformable structures that can extend horizontally on both disconnected sides, this horizontal length increase can be used as the most important design parameter for adjusting the center frequency of the tag assembly downwards, and can also be used as a design parameter for controlling the radiation gain based on the adjustment of the relative lengths of the first segment 520 and the second segment 540 of the tag antenna 510. Figure 9c The diagram shows a deformable structure of the second segment 540 of antenna 510 that can be bent downwards on the disconnected side, and... Figure 9dThe diagram illustrates a deformable structure in which the first segment 520 of the antenna 510 can be bent upwards on the disconnected side. To achieve such a bending structure, the mounting slots within the tag housings 500a and 500b may include more horizontal slots (e.g., Figure 5 560d in the middle) and / or vertical slots (e.g., Figure 5 The effective resonant length of the tag antenna 510 can be increased without changing the external size of the radiating element 320 (560e). However, the upward bending of the first segment 520 and the downward bending of the second segment 540 of the antenna 510, as well as the corresponding additional horizontal slots, are optional. Those skilled in the art can choose different slotting methods as needed, and the present invention is not intended to limit this.

[0079] Figure 10 A diagram illustrating the radiation pattern of a tag antenna with variable main radiation directivity according to an embodiment of the present invention, based on the maximum radiation gain of the azimuth angle, is shown, illustrating the radiation pattern in the YZ plane (phi = 90°) with a center frequency of 920 MHz in the UHF band. Considering the case of attachment to a metallic object, the size of the metal plate capable of surface stamping can be set to 85 × 58 mm, and the radiation gain can change with variations in the size and relative position of the metallic object.

[0080] The typical tag antenna 510 has its maximum radiation gain radiated in a direction perpendicular to the surface of the metal object. However, the radiating element 320 of the present invention, which has a variable main radiation directivity, can be located on one side of the metal plate 330, and its main radiation can be oriented at a 43° angle from the vertical direction. As shown, it exhibits a maximum radiation gain of 4.15 dBi for a long-range radiation mode and a left-right asymmetry in the YZ plane.

[0081] The structure of the radiating element 320, with its maximum radiation gain biased at a specific pointing angle, effectively improves the problem of low long-range identification performance caused by the height difference between the RFID reader antenna and the tag antenna. By simply changing the vertical and horizontal attachment directions of the tag based on the height of the tag attachment object and the left-right identification angle deviation, the communication sensitivity of the RFID reader can be effectively improved in the presence of directional differences (height and left-right differences). That is, when the tag attachment height is higher than that of the RFID reader, the tag radiation gain directionality can be shifted downwards by attaching the tag housing 320 to the lower side of the metal plate 330; conversely, when the tag attachment height is lower than that of the RFID reader, the tag radiation gain directionality can be shifted upwards by attaching the tag housing 320 to the upper side of the metal plate 330. By attaching the same tag housing 320 in different directions according to the attachment height difference or the left-right identification angle deviation, the direction of the tag's maximum radiation gain can be biased, allowing control of the tag's main radiation directionality without the use of additional mechanical supports.

[0082] Figure 11 The results of measuring the long-range identification distance of an RFID tag antenna with variable main radiation directivity according to an embodiment of the present invention in the UHF RFID band are shown. The tag assembly 300 used for measurement can be positioned in the center of a square metal plate with a side length of 15 cm, which serves as the attachment object, and the measurement can be performed in an anechoic chamber using the Voyantic Tagformance system with a standard power of 36 dBm. The identification distance of the tag assembly attached to the metal attachment object can be measured from the vertical / frontal direction. Figure 10 As shown, a maximum identification distance of 14m can be achieved at the center frequency of 920MHz in the UHF band.

[0083] This invention describes an RFID tag assembly. By constructing a flexible metal wire into a three-dimensional shape for use as an RFID tag radiating element in the UHF band and mounting this radiating element asymmetrically onto a metal plate, the maximum radiation gain direction of the RFID tag assembly can be tilted at a specific angle. In various RFID application environments, where it is difficult to obtain the height position of the RFID tag assembly and the line-of-sight (LOS) distance of the reader antenna used for identification, the readable identification distance performance of existing RFID tags deteriorates sharply. In particular, when identifying RFID tags from a horizontally tilted direction or when the height position of the tag attached to facility assets is high or low, the RCS cross-sectional area of ​​the tag relative to the reader antenna decreases sharply, reducing reflection and scattering efficiency and leading to a decrease in RFID tag identification performance. The RFID tag proposed in this invention, in such special cases, effectively ensures the readable identification distance performance of the tag and improves the performance of the RFID system by changing the tag attachment method to make the maximum radiation gain direction of the tag deflect vertically and horizontally. The use of metal wire in the tag radiating element in this invention provides tag durability in high-temperature application environments and thermal shock environments, greatly improving the tag's degradation characteristics.

[0084] Specifically, the label radiating element, with its metal wire set and encapsulated within the plastic structure, and the additionally combined metal plate are physically constructed separately and joined by a mounting mechanism. This allows for embossing or stamping operations that protrude from the surface of the metal plate, and such embossing operations offer the advantage of not affecting the label's appearance or electrical properties. Furthermore, the separately constructed metal plates can be of various sizes and are combined with the metal wire embedded within the plastic structure after being constructed independently.

[0085] As described above, this invention provides semi-permanent and intuitively identifiable markings achieved through mechanical embossing / stamping on a metal plate surface to meet the requirements of specific application areas, while also extending the application to additionally realize electrical RFID tag functionality. Existing RFID tags do not have a metal plate on their surface, or even if they do, physical stamping / embossing on the tag surface physically damages the tag itself, causing waterproofing issues and reduced tag durability. This invention improves tag durability and design flexibility by independently separating the electrical connection of the tag antenna from the fundamental design parameters that determine the tag's radiation gain. In other words, the electrical RFID tag design is separated from the metal plate, and then the two are combined through an mounting device, thereby ensuring that the mechanical stamping / embossing operation does not affect the tag's electrical / physical properties.

[0086] Exemplary embodiments have been described above. However, it should be understood that various modifications can be made to the above exemplary embodiments without departing from the spirit and scope of the invention. For example, if suitable results can be achieved if the described techniques are performed in a different order and / or if components in the described system, architecture, device, or circuit are combined in different ways and / or replaced or supplemented by other components or their equivalents, then correspondingly, these other modified embodiments also fall within the scope of protection of the claims.

Claims

1. A radio frequency identification tag assembly, characterized in that, The radio frequency identification tag component includes: A metal sheet having an upper surface and a lower surface; A radiating element includes a tag housing arranged along one side of the upper surface of a metal plate. The tag housing contains an IC chip, an antenna, and a circuit board electrically connecting the IC chip and the antenna. The antenna is spaced apart from the metal plate. The antenna is made of metal. The antenna has a first segment and a second segment parallel to the upper surface of the metal plate. The first segment has a first gap with the upper surface of the metal plate, and the first segment and the second segment have a second gap. The upper surface of the metal plate is at an angle to the plane where the antenna is located, and the straight line intersecting the plane where the upper surface of the metal plate and the antenna is located is parallel to the extension direction of the antenna.

2. The radio frequency identification tag assembly as described in claim 1, characterized in that, The IC chip operates in the UHF band.

3. The radio frequency identification tag assembly as described in claim 1, characterized in that, One end of the first segment of the antenna is connected to one end of the second segment via a conductor.

4. The radio frequency identification tag assembly as described in claim 3, characterized in that, The conductor is the bend between the first segment and the second segment of the antenna, and the first segment, the second segment, and the bend integrally constitute the antenna.

5. The radio frequency identification tag assembly as described in claim 3, characterized in that, The conductor is a wire arranged separately from the antenna within the housing.

6. The radio frequency identification tag assembly as described in claim 1, characterized in that, The plane containing the antenna is perpendicular to the upper surface of the metal plate.

7. The radio frequency identification tag assembly as described in claim 1, characterized in that, The metal plate serves as the ground plane for the RFID tag assembly.

8. The radio frequency identification tag assembly as described in claim 1, characterized in that, The radio frequency identification tag assembly is configured by attaching the lower surface of the metal plate to the object to be identified.

9. The radio frequency identification tag assembly as described in claim 3, characterized in that, The housing has mounting slots inside to embed the antenna and the circuit board.

10. The radio frequency identification tag assembly as claimed in claim 9, characterized in that, The mounting slot includes: Multiple recesses for embedding an antenna, wherein the multiple recesses include multiple horizontal slots and multiple vertical slots, the multiple horizontal slots including a first horizontal slot and a second horizontal slot, the first horizontal slot being configured to embed a first segment of the antenna, the second horizontal slot being configured to embed a second segment of the antenna, and the vertical slots being configured to embed the conductor; and Multiple receiving spaces, each of which is used to receive the circuit board.

11. The radio frequency identification tag assembly as claimed in claim 10, characterized in that, Each of the plurality of horizontal slots intersects with at least one of the plurality of receiving spaces. The plurality of horizontal grooves are parallel to the upper surface of the metal plate, and the distances between the plurality of horizontal grooves and the upper surface of the metal plate are not equal. The plurality of accommodating spaces are separated from the vertical groove by a plurality of distances.

12. The radio frequency identification tag assembly as claimed in claim 10, characterized in that, The first segment of the antenna extends into the third horizontal slot of the plurality of horizontal slots, and / or the second segment of the antenna extends into the fourth horizontal slot of the plurality of horizontal slots.

13. The radio frequency identification tag assembly as described in claim 12, characterized in that, The first horizontal slot is configured to accommodate a first segment of the antenna of different lengths, and the second horizontal slot is configured to accommodate a second segment of the antenna of different lengths.

14. The radio frequency identification tag assembly as claimed in claim 1, characterized in that, The label housing is fixed to the metal plate by a positioning mechanism so that the lower surface of the label housing remains horizontal relative to the upper surface of the metal plate.

15. The radio frequency identification tag assembly as described in claim 14, characterized in that, The positioning mechanism includes a threaded component for securing the label housing to the metal plate and a grid-shaped fixing component located on the upper surface of the metal plate.

16. The radio frequency identification tag assembly as claimed in claim 1, characterized in that, The metal sheet is embossed, stamped, laser-processed, or printed with visual identifiers.

17. The radio frequency identification tag assembly as described in any one of claims 1-16, characterized in that, The direction of the maximum radiation gain of the RFID tag assembly is tilted from the direction perpendicular to the metal plate.

18. An identifiable object having an RFID tag assembly attached as claimed in any one of claims 1-16.

19. The identifiable object as described in claim 18, characterized in that, The identifiable objects include facility assets and shelving.

Images