RFID tag element and tool having RFID tag element

Abstract

The invention discloses an RFID tag element and a tool for attaching the RFID tag element. A radio frequency identification tag element has one end and the other end in a longitudinal direction, and includes: a substrate; the first through hole is formed in one end of the radio frequency identification tag element in the substrate; the second through hole is formed in the other end of the radio frequency identification tag element in the substrate; the bottom layer is located at the bottom of the substrate, one end of the bottom layer is close to one end of the radio frequency identification tag element, and the other end is close to the other end of the radio frequency identification tag element; the middle layer is located between the top and the bottom of the substrate, one end of the middle layer is electrically connected with one end of the bottom layer through the first through hole, and the other end of the middle layer extends towards the other end of the radio frequency identification tag element; the top layer is located at the top of the substrate, the other end of the top layer is electrically connected with the other end of the bottom layer through the second through hole, one end of the top layer is separated from the first through hole, and the top layer is provided with a gap; and a chip bonded to the top layer across the gap of the top layer.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency identification, and more particularly to a radio frequency identification (RFID) tag element and a tool having the same. Background Art

[0002] With the development of sensors of various frequency bands and low-power Bluetooth technology, RFID technology has been widely used in many industries. In a static environment, in addition to the sensitivity and recognition range of RFID tags, the polarization mismatch between the RFID reader antenna and the object to be identified is also becoming increasingly prominent. Especially in the inventory management of small tool warehouses or batch identification through access gates, the tools are randomly placed, and it is difficult to ensure that the tools with RFID tags remain in a fixed position or to ensure that the distance between the tag and the reader is roughly the same. When multiple objects to be identified exist in arbitrary postures and cannot be placed in a unified position, adjacent objects of different materials may cause the center frequency of the RFID tag to shift. In addition, the rotation direction of the object to be identified may cause the attached RFID tag to have inconsistent directionality and polarization, thereby limiting the maximum sensing distance of the tag.

[0003] When an RFID tag is attached to a symmetrical structure or cylindrical object (such as small tools, wood, furniture, etc.), it is difficult to directly confirm its installation position and direction from the outside when inserting the tag element. Summary of the invention

[0004] The present invention aims to overcome the above problems in the prior art and provides a new RFID tag design, which enables the RFID tag element itself to have a ground plane, so as to minimize the deviation between the forward radiation gain and the backward radiation gain. Even when used in an application environment where multiple objects to be identified are arranged in any direction, the identification performance of batch RFID tags can be improved.

[0005] According to a first aspect of the present invention, there is provided a radio frequency identification tag element, which has one end and the other end in a length direction, and comprises: a substrate; a first through hole, which is arranged in the substrate at one end of the radio frequency identification tag element; a second through hole, which is arranged in the substrate at the other end of the radio frequency identification tag element; a bottom layer, which is located at the bottom of the substrate, one end of the bottom layer is close to one end of the radio frequency identification tag element and the other end of the bottom layer is close to the other end of the radio frequency identification tag element; an intermediate layer, which is located between the top and the bottom of the substrate, one end of the intermediate layer is electrically connected to one end of the bottom layer through the first through hole and the other end of the intermediate layer extends toward the other end of the radio frequency identification tag element; a top layer, which is located at the top of the substrate, the other end of the top layer is electrically connected to the other end of the bottom layer through the second through hole, one end of the top layer is spaced apart from the first through hole, and the top layer has a gap; and a chip, which is bonded to the top layer across the gap of the top layer, wherein the distance between the other end of the intermediate layer and one end of the radio frequency identification tag element does not exceed the distance between the gap and one end of the radio frequency identification tag element.

[0006] According to a second aspect of the present invention, there is provided a radio frequency identification tag element, wherein the radio frequency identification tag element has one end and the other end along the length direction, and comprises: a substrate; a first through hole, wherein the first through hole is arranged in the substrate at one end of the radio frequency identification tag element; a second through hole, wherein the second through hole is arranged in the substrate at the other end of the radio frequency identification tag element; a bottom layer, wherein the bottom layer is located at the bottom of the substrate, wherein one end of the bottom layer is close to one end of the radio frequency identification tag element and the other end of the bottom layer is close to the other end of the radio frequency identification tag element; an intermediate layer, wherein the intermediate layer is located between the top and the bottom of the substrate, wherein one end of the intermediate layer is electrically connected to one end of the bottom layer through the first through hole and the other end of the intermediate layer is connected to the other end of the bottom layer through the second through hole, and the intermediate layer has a gap; a chip, wherein the chip is bonded to the intermediate layer across the gap of the intermediate layer; a top layer, wherein the top layer is located at the top of the substrate, wherein one end of the top layer is spaced apart from one end of the radio frequency identification tag element and the other end of the top layer is spaced apart from the other end of the radio frequency identification tag element, and the top layer has a mechanical hole, wherein the mechanical hole at least partially overlaps with the gap of the intermediate layer and the chip is accommodated in the mechanical hole.

[0007] According to a third aspect of the present invention, a tool is provided. The tool has a surface, and the RFID tag element according to any one of the above items is attached to the surface.

[0008] According to a fourth aspect of the present invention, a tool is provided, wherein the tool has a cavity configured to accommodate the RFID tag element as described in any one of the above items, and the RFID tag element is arranged in the cavity along the length direction.

[0009] Other features and aspects will become apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The following is a brief introduction to the drawings required for use in the embodiments or prior art descriptions. Obviously, the drawings described below are embodiments of the present invention, and a person of ordinary skill in the art can obtain other drawings based on these drawings without creative work, wherein:

[0011] Figure 1a and Figure 1b A side view and an exploded view respectively show an RFID tag element according to one embodiment of the present invention.

[0012] Figure 2a and Figure 2b A side view and an exploded view respectively show an RFID tag element according to another embodiment of the present invention.

[0013] Figure 3a and Figure 3b The impedance characteristics of an RFID tag element according to one embodiment of the present invention and an RFID tag element according to another embodiment are shown respectively when various parameters are set based on the central frequency band of 920 MHz in the UHF band.

[0014] Figure 3c The process of fine-tuning the center frequency of the RFID tag element by adjusting the length D1 of the top layer is schematically shown.

[0015] Figure 4a and Figure 4b Schematic diagrams showing the RFID tag elements of the first embodiment and the second embodiment of the present invention being attached to a planar surface of a tool and in a groove on the surface of the tool, respectively.

[0016] Figure 4c It is a schematic diagram showing that the RFID tag element according to the third embodiment of the present invention is attached to the surface of a tool in opposite directions.

[0017] Figure 5a The radiation patterns of the RFID tag elements in the cross-sectional direction when the RFID tag elements of the first embodiment and the second embodiment of the present invention are attached to the planar surface of the tool and in the grooves on the tool surface are shown.

[0018] Figure 5bThe figure shows the radiation patterns in the cross-sectional direction when the RFID tag element according to the second embodiment of the present invention is attached to grooves of the same depth and in tools of different widths.

[0019] Figure 6 It is shown that when the RFID tag element according to the third embodiment of the present invention is attached to a tool, as the tool is rotated around its axis in the length direction, the recognizable distance performance of the RFID tag element changes.

[0020] Figure 7 It is a schematic diagram showing that the RFID tag element according to the fourth embodiment of the present invention is arranged in a tool.

[0021] Figure 8 The radiation patterns of the RFID tag element in the cross-sectional direction when the RFID tag element according to the fourth embodiment of the present invention is inserted into the tool at multiple angles are shown.

[0022] Fig. 9 It is shown that when the RFID tag element of the fourth embodiment of the present invention is inserted into a tool at multiple angles, the RFID tag element can recognize changes in distance performance as the angle changes.

[0023] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical components that are common to the figures. It is contemplated that components and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0024] The drawings are for illustrative purposes and are not to be considered to scale unless specifically stated to be to scale. The drawings are schematic to aid understanding and may not include all aspects or information as compared to actual representation.

[0025] In the accompanying drawings, similar components and / or features may have the same reference numeral, and various components of the same type may be distinguished by a letter following the reference numeral. If only the preceding reference numeral is used in the specification, the description applies to any similar components having the same preceding reference numeral. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0029] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes such as design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0030] Unless otherwise defined, the technical or scientific terms used in the claims and description shall have the usual meaning understood by persons with ordinary skills in the technical field to which the invention belongs. The words "first", "second" and similar words used in the patent application description and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "one" or "a" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalent elements, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0031] In this application, unless otherwise specified, all embodiments and preferred embodiments, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution. In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0032] In the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0033] The core advantage of UHF passive RFID tag technology is that it can use the backscattering communication protocol to identify multiple tags simultaneously at a long distance without contact. The characteristics of UHF electromagnetic waves make the loss and dielectric constant of the tag attachment material have a significant impact on the tag performance. The spatial radiation gain pattern of the tag is not only affected by its own design, but also closely related to the object, position, polarization matching of the reader antenna and the surrounding electromagnetic environment to which the tag is attached. When the tag is attached to a dielectric material (such as plastic, glass or high dielectric constant ceramic), the dipole-shaped tag will form a uniform radiation pattern around the insertion axis when inserted into these materials. Although the specific radiation gain will be affected by the material loss and dielectric constant, as long as the symmetry of the material is maintained, the spatial omnidirectional (Omni) radiation pattern of the tag remains roughly unchanged.

[0034] In practical applications, when the tag is attached to a dielectric material and the tag's radiation gain is required to be concentrated in a specific direction (usually the front), it is possible to consider giving the tag a grounding function or coating it with an additional conductive medium and maintaining an appropriate spacing.

[0035] When an RFID tag needs to be closely attached to a metal surface, it is usually necessary to perform complex impedance matching with the tag's chip and install a ground plane on the tag. Although this method can conveniently use the tag's ground plane and the metal conductive medium as a ground plane, it may reduce the tag's input impedance bandwidth, and the tag's electrical characteristics will be significantly affected by the size and attachment position of the conductive medium. In addition, due to the asymmetry of the ground plane, the tag's radiation pattern may deviate greatly, and when the size of the metal attachment object is relatively large, the tag's radiation gain tends to be concentrated on the upper part of the ground plane. When the tag is attached to a conductive object with a large area, the radiation gain of its front (towards the reader) and back is significantly different compared to the size of the tag, and this difference is particularly obvious between the front of the tag and the back of the conductive object.

[0036] In order to improve this biased radiation gain pattern, one method is to process the metal material itself into a disconnected or closed loop groove, making it a part of the tag antenna. However, the radiation gain of this method is relatively low, and it is difficult to arbitrarily process metal objects in practical applications. In addition, the final packaging process including chip molding is difficult, so this method is not widely used.

[0037] When using an RFID reader antenna to identify an electronic tag attached to a metal surface, in order to achieve the maximum readability distance, the cross-sectional area (RCS) of the electronic tag should be as positive as possible toward the radiation area of ​​the reader antenna. Most electronic tags designed for metal surfaces are designed to have the maximum radiation gain facing the positive direction perpendicular to the metal surface. However, when the tag is not at the same height as the reader antenna or the tag is attached at an inclined angle, the RCS decreases sharply, resulting in a significant decrease in receiving sensitivity. In applications such as managing high-rise shelves in logistics warehouses or preventing product loss on shelves, in addition to the recognition performance of the tag in a stationary state, a wider radiation gain angle is also an important factor. In addition, when multiple tagged objects are placed in arbitrary directions instead of facing forward, maintaining a uniform radiation pattern of the tag on a specific plane is critical to improving the practicality of the RFID system.

[0038] This means that if the polarization of the RFID reader antenna and the tag attached to the metal surface is not consistent, and the radiation gain of the tag is biased towards a specific direction, the recognition rate of the tag will vary significantly with the recognition angle of the reader antenna. This may lead to a significant reduction in batch recognition rate when multiple objects to be identified are loaded in any orientation.

[0039] Therefore, there is a need for an RFID tag element that can maintain tag performance when attached to both conductive objects and dielectric objects, and that can enable the tag's radiation gain to maintain a uniform radiation pattern in a specific direction when including conductive objects and dielectric objects in any direction, thereby improving the usability of the RFID tag in actual application environments.

[0040] Figure 1a and Figure 1b A side view and an exploded view of an RFID tag element 100 according to an embodiment of the present invention are respectively shown.

[0041] The RFID tag element 100 is arranged along the length direction ( Figure 1aThe RFID tag element 100 includes a substrate 110, a bottom layer 120, an intermediate layer 130, and a top layer 140. As an example, the substrate 110 may be made of a dielectric material, and the bottom layer 120, the intermediate layer 130, and the top layer 140 may be made of a conductive material (e.g., copper), wherein the bottom layer 120, the intermediate layer 130, and the top layer 140 may be manufactured into a very thin planar form by various processes (e.g., etching). The bottom layer 120 is located at the bottom of the substrate 110 and extends along the length direction of the RFID tag element 100, wherein one end 120A of the bottom layer 120 is close to one end 100A of the RFID tag element 100 and the other end 120B of the bottom layer 120 is close to the other end 100B of the RFID tag element 100. The middle layer 130 is located between the top and bottom of the substrate 110, one end 130A of the middle layer 130 is close to the one end 100A of the RFID tag element 100, and the other end 130B of the middle layer 130 extends toward the other end 100B of the RFID tag element 100. The top layer 140 is located on the top of the substrate 110, the other end 140B of the top layer 140 is close to the other end 100B of the RFID tag element 100, and one end 140A of the top layer 140 extends toward the one end 100A of the RFID tag element 100 without reaching the one end 100A of the RFID tag element 100. The top layer 140 and the middle layer 130 are connected in the longitudinal direction ( Figure 1a In the embodiment, the top layer 140 and the middle layer 130 are at least partially overlapped on the y-axis shown in FIG. 1 ), that is, the projection of the top layer 140 on the bottom layer 120 and the projection of the middle layer 130 on the bottom layer 120 at least partially overlap. In addition, the top layer 140 also has a gap 150, and the chip 160 of the RFID tag element 100 is bonded to the top layer 140 across the gap 150. Preferably, the chip 160 may be covered with a protective layer (such as epoxy resin).

[0042] A distance D1 between the other end 130B of the intermediate layer 130 and the one end 100A of the RFID tag element 100 does not exceed a distance D2 between the gap 150 and the one end 100A of the RFID tag element 100 .

[0043] In addition, the RFID tag element 100 further includes a first through hole 170A disposed at one end 100A of the RFID tag element 100 in the substrate 110 and a second through hole 170B disposed at the other end 100B of the RFID tag element 100 in the substrate 110. As an example, a perforated structure may be manufactured by mechanical processing, and then a conductive material (e.g., copper) may be coated on the inner surface of the perforated structure so that different objects conductively connected to the conductive material can be connected, thereby forming a through hole. The first through hole 170A connects one end 130A of the middle layer 130 to one end 120A of the bottom layer 120, and the second through hole 170B connects the other end 140B of the top layer 140 to the other end 120B of the bottom layer 120.

[0044] Figure 1a and Figure 1b In the embodiment shown in , the bottom layer 120 can be used as the ground layer of the RFID tag element 100. The bottom layer 120 and the middle layer 130 can have a spacing of H1 (for example, through the first through hole 170A), and the bottom layer 120 and the top layer 140 can have a spacing of H1+H2 (for example, through the second through hole 170B), that is, the spacing between the middle layer 130 and the top layer 140 can be H2. The RFID tag element 100 with such a three-dimensional structure can effectively reduce the area of ​​the tag element within a limited space, and by making the top layer 140 and the middle layer 130 closely coupled in a disconnected manner rather than short-circuited, the working impedance bandwidth of the RFID tag element 100 can be improved, and adjustability is provided.

[0045] In fact, the center frequency of the RFID tag element 100 can be adjusted by changing various design variables, including: the spacing H1 between the bottom layer 120 and the middle layer 130, the spacing H2 between the middle layer 130 and the top layer 140, the position of the other end 130B of the middle layer 130, the length T1 of the top layer 140, the position of the chip 160 on the top layer 140 (here, represented by the distance off1 between the chip 160 and the other end 140B of the top layer 140), etc. However, in the assembled state, it is difficult to adjust the spacing H1 between the bottom layer 120 and the middle layer 130, the spacing H2 between the middle layer 130 and the top layer 140, and the position of the other end 130B of the middle layer 130. In the case where the distance D1 between the other end 130B of the middle layer 130 and one end 100A of the RFID tag element 100 exceeds the distance D2 between the gap 150 and one end 100A of the RFID tag element 100, even very slight changes in other variables will greatly affect the center frequency of the RFID tag element 100. Therefore, in this embodiment, the distance D1 between the other end 130B of the intermediate layer 130 and the one end 100A of the RFID tag element 100 is preset to be less than the distance D2 between the gap 150 and the one end 100A of the RFID tag element 100. Figure 1a In the embodiment, the other end 130B of the middle layer 130 is substantially aligned with the side of the gap 150 closer to the end 100A of the RFID tag element 100. Furthermore, the intervals H1 and H2 are predetermined, and the center frequency and impedance matching of the RFID tag element 100 are fine-tuned by fine-tuning the position off1 of the chip 160 and the length T1 of the top layer 140.

[0046] In addition, the width W1 of the RFID tag element 100 is designed to be very narrow compared to its length, so the equivalent capacitance formed by the close coupling between the top layer 140 and the middle layer 130 through the bottom layer 120 and the through holes 170A and 170B on both sides connected to each other can easily achieve complex impedance matching of the chip 160 of the RFID tag element. And by making the RFID tag element 100 itself have a ground plane, the RFID tag element 100 can be used to attach to a metal surface or insert into a metal environment and various dielectric materials.

[0047] Figure 2a and Figure 2b A side view and an exploded view of an RFID tag element 200 according to another embodiment of the present invention are respectively shown.

[0048] The RFID tag element 200 has one end 200A and the other end 200B along the length direction (x-axis). The RFID tag element 200 includes a substrate 210, a bottom layer 220, an intermediate layer 230, and a top layer 240. As an example, the substrate 210 can be made of a dielectric material, and the bottom layer 220, the intermediate layer 230, and the top layer 240 can be made of a conductive material (e.g., copper), wherein the bottom layer 220, the intermediate layer 230, and the top layer 240 can be manufactured into a very thin planar form by various processes (e.g., etching). The bottom layer 220 is located at the bottom of the substrate 210 and extends along the x-axis direction, wherein one end 220A of the bottom layer 220 is close to one end 200A of the RFID tag element 200 and the other end 220B of the bottom layer 220 is close to the other end 200B of the RFID tag element 200. The middle layer 230 is located between the top and bottom of the substrate 210, one end 230A of the middle layer 230 is close to one end 200A of the RFID tag element 200, and the other end 230B of the middle layer 230 is close to the other end 200B of the RFID tag element 200. The middle layer 230 has a gap 250. Optionally, the gap 250 can be located at the middle position of the middle layer 230 in the x-axis direction. The chip 260 of the RFID tag element 200 is bonded to the middle layer 230 across the gap 250, and preferably, the chip 260 can be covered with a protective layer. The top layer 240 is located on the top of the substrate 210, one end 240A of the top layer 240 is spaced apart from one end 200A of the RFID tag element 200 and the other end 240B of the top layer 240 is spaced apart from the other end 200B of the RFID tag element 200. The top layer 240 has a mechanical hole 280, and the mechanical hole 280 is spaced apart from the gap 250 of the middle layer 230 in the longitudinal direction ( Figure 2a The top layer 240 is at least partially overlapped on the y-axis shown in FIG. 2 , and the chip 260 and the optional protective layer of the chip 260 can be accommodated in the mechanical hole 280. The mechanical hole 280 defines a cavity structure in the top layer 240, thereby facilitating the installation of the chip 260 in the middle layer 230 and playing the role of avoiding the chip 260 and protecting the chip 260. Preferably, the top layer 240 is symmetrical with respect to the center line cl of the RFID tag element 200 in the x-axis direction. The top layer 240 and the middle layer 230 are longitudinally ( Figure 2a at least partially overlap on the y-axis shown in ).

[0049] In addition, the RFID tag element 200 further includes a first through hole 270A provided at one end 200A of the RFID tag element 200 in the substrate 210 and a second through hole 270B provided at the other end 200B of the RFID tag element 200 in the substrate 210. The first through hole 270A connects one end 230A of the middle layer 230 to one end 220A of the bottom layer 220, and the second through hole 270B connects the other end 230B of the middle layer 230 to the other end 220B of the bottom layer 220.

[0050] exist Figure 2a and Figure 2b In the embodiment shown in , the bottom layer 220 can be used as the grounding layer of the RFID tag element 200. The bottom layer 220 and the middle layer 230 can have a spacing of H3, and the middle layer 230 and the top layer 240 can have a spacing of H4. The length D1 of the top layer 240 along the x-axis direction can be used as a design variable. As the material of the installation object and the installation depth change, the RFID tag element 200 can be fine-tuned by adjusting the design variable D1. When the length D1 of the top layer 240 increases, the equivalent capacitance between the top layer 240 and the middle layer 230 increases, thereby reducing the center frequency of the RFID tag element 200; on the contrary, when the length D1 of the top layer 240 decreases, the equivalent capacitance between the top layer 240 and the middle layer 230 decreases, thereby increasing the center frequency of the RFID tag element 200. The sheet structure of the top layer 240 can easily improve the deviation caused by the change of the surrounding environment outside the RFID tag element 200 and the change of the installation environment. In addition, the protrusion of the top of the RFID tag element 200 can be reduced, the friction during the installation process can be reduced, and the convenience can be improved. The structure shown in this embodiment can be used as a technical solution that can efficiently and conveniently achieve impedance matching of UHF band chips through conventional PCB manufacturing processes.

[0051] Figure 3a and Figure 3b The impedance characteristics of the RFID tag element 100 of one embodiment of the present invention and the RFID tag element 200 of another embodiment of the present invention are shown respectively when various parameters are set based on the central frequency band of the UHF band of 920 MHz. Figure 3a As shown, the imaginary component of the input impedance of the RFID tag element 100 is relatively low, 0.23+j137.57Ω (f 0 =920MHz), and Figure 3b As shown, the imaginary component of the input impedance of the RFID tag element 200 is set to a relatively high 7.48+j212.47Ω (f 0=920MHz). The most critical design variables of the RFID tag element 100 and the RFID tag element 200 described in this article are the distance between the through holes set on both sides of the RFID tag element (i.e., the distance between through hole 170A and through hole 170B, the distance between through hole 270A and through hole 270B, hereinafter referred to as "through hole spacing") and the spacing between layers in the multi-layer RFID tag element (spacing H1 and H2 in RFID tag element 100 and spacing H3 and H4 in RFID tag element 200, hereinafter referred to as "spacing between layers"). The through hole spacing is the most important design variable for adjusting the inductance component of the RFID tag element, and the spacing between layers is the most important design variable for adjusting the capacitance of the RFID tag element. However, the thickness of the RFID tag element and the thickness of each layer, as well as the length of each layer passing through the through hole, which serve as these design variables, cannot be greatly changed after the manufacturing process of the RFID tag element is determined, and can only be fine-tuned by other means.

[0052] Figure 1a and Figure 1b The electrical parameters of the RFID tag element 100 can be adjusted by adjusting the length T1 of the top layer 140 and the bonding position off1 of the chip 160. Figure 2a and 2b The RFID tag element 200 can achieve fine tuning of the center frequency of the RFID tag element 200 by adjusting the length D1 of the top layer 240 . Figure 3c The process of fine-tuning the center frequency of the RFID tag element 200 by adjusting the length D1 of the top layer 240 is schematically shown. This fine-tuning of the design variables of the RFID tag element provides a convenient means for easily fine-tuning according to the changes and tolerances of the materials of various attached objects. As an example, the input impedances of the RFID tag element 100 and the RFID tag element 200 disclosed in this article are formed to be 0.23+j137.57Ω and 7.48+j212.47Ω respectively based on 920MHz. It can be seen that the imaginary input impedance that needs to be redesigned as the chip changes can be adjusted by adjusting the distributed area, thereby improving the availability of the RFID tag element.

[0053] Typically, the RFID tag element used to attach to a metal surface itself has a ground plane, and when the ground plane is connected to the metal surface in a short-circuit manner, the attached metal surface itself serves as the common ground plane of the RFID tag element. Therefore, when the area of ​​the attached metal object is large, the radiation gain and spatial radiation pattern of the RFID tag element will also be greatly affected as the attachment position changes. The RFID tag element attached to the metal object has a significant difference in the radiation gain pattern between the front and back. In order to improve the aesthetics and reduce the risk of damage to the RFID tag element in practical applications, grooves are often made on the metal surface and the RFID tag element is embedded therein. However, as the embedding depth increases, the radiation efficiency of the tag element decreases, resulting in a reduction in the spatial radiation gain, which in turn affects its long-distance recognition capability.

[0054] Figure 4a The schematic diagram shows that the RFID tag element 100 of the first embodiment of the present invention is attached to the planar surface of the tool 400. The RFID tag element 100 has a protruding chip, which may be covered by a protective layer, and the tool 400 is made of a narrow and long metal. The planar surface 401 of the tool 400 is not provided with any cavity or groove for accommodating the RFID tag element 100.

[0055] Figure 4b A schematic diagram showing a second embodiment of the present invention in which the RFID tag element 100 is attached to the surface of a tool 410 is shown, and Figure 4c FIG. 4 is a schematic diagram showing an RFID tag element 100 according to a third embodiment of the present invention attached to a surface of a tool 410 in the opposite direction. Figure 4b to Figure 4c In the illustrated embodiment, the RFID tag element 100 has a protruding chip protected by molding, and the tool 410 is made of a narrow and long metal. The surface of the tool 410 is provided with a groove 411 for accommodating the RFID tag element 100.

[0056] The tool can be made not only of metal, but also of many other materials, such as dielectric materials, such as plastic or wood. For the convenience of testing and simulation experiments, a wrench is shown here as a representative of the tool, but other types of tools are also applicable. Figures 4a to 4c Shows the Figure 1a to Figure 1b The RFID tag element 100 is installed on the tool 400 and the tool 410. Those skilled in the art will understand that Figure 2a to Figure 2b The RFID tag element 200 in the embodiment can also be Figures 4a to 4c The method shown is installed on tool 400 and tool 410. Figure 4cAs shown, when the RFID tag element is installed in the opposite direction, the chip part is placed in the groove of the metal surface and will not be exposed to the outside, which effectively reduces the risk of environmental factors causing damage to the RFID tag element. When the RFID tag element 100 is selected, the chip 160 preferably protrudes from the top layer 140 to a certain height. In this way, the thickness of the protective layer can be increased, and a certain distance is formed between the surface of the groove 411 and the top layer of the RFID tag element 100, forming an additional equivalent capacitance, which can be used as an additional parameter for adjusting the center frequency of the RFID tag element 100. By adjusting the distance between the RFID tag element 100 and the surface of the groove 411 (such as by changing the thickness of the protective layer), the center frequency of the RFID tag element 100 can be adjusted.

[0057] Compared with the prior art, the RFID tag element of the present invention can significantly reduce the difference between the forward radiation gain and the backward radiation gain under different attachment conditions, whether attached to a metal object or a material with different dielectric constants (such as wood or plastic).

[0058] Figure 5a The RFID tag element 100 of the first embodiment and the second embodiment of the present invention is attached to a planar surface 401 of a tool 400 ( Figure 4a ) and in the groove 411 on the surface of the tool 410 ( Figure 4b ) is a radiation pattern of the RFID tag element 100 in the cross-sectional direction. As an example, the groove 411 is set to have a depth of 0.4 mm to 0.8 mm, but the present invention is not limited thereto. Here, the cross-sectional plane refers to a plane perpendicular to the length direction, that is, Figure 4a The plane is defined by the y-axis and the z-axis in . Taking 920 MHz as the reference frequency, the RFID tag element 100 exhibits a radiation gain of 2.2 dBi on the front side (+y direction) and 1.3 dBi on the back side (-y direction) when attached to the surface 401 and embedded in the groove 411. In the side direction, the side radiation gain of the RFID tag element 100 attached to the surface 401 is 1.6 dBi, while that embedded in the groove 411 is 1.5 dBi. Although the back radiation gain is 0.9 dBi lower than the front radiation gain, this difference is significantly reduced compared to the difference between the front and back radiation gains of tags attached to conventional metal surfaces.

[0059] Figure 5b The figure shows the radiation pattern in the cross-sectional direction when the RFID tag element 100 of the second embodiment of the present invention is attached to the groove 411 of the same depth of the tools with different widths. Generally, the RFID tag element with a ground plane will show a trend of increasing front radiation gain and decreasing back radiation gain as the metal area of ​​the attachment tool increases. Figure 5bIn the figure, the radiation pattern data is provided when the tool width is W, 2W and 3W (where W is the reference width). Figure 5b As shown, the difference in front radiation gain under different widths is 0.1dBi to 0.3dBi, and the difference in back radiation gain is 0.3dBi to 0.5dBi. In this field, the radiation pattern deviation caused by different tool widths is considered to have little effect on the readable recognition distance performance of RFID tag components in actual application environments.

[0060] Figure 6 The RFID tag element 100 of the third embodiment of the present invention is attached to a tool 400 ( Figure 4c ), as the tool 400 rotates around its axis in the length direction (x-axis direction), the recognizable distance performance of the RFID tag element 100 changes. Figure 6 As schematically shown in the upper left corner of FIG. , the direction of the tool 400 is defined as 0° when the front radiation direction of the RFID tag element 100 faces the RFID reader, the direction of the tool 400 is defined as 90° when the front radiation direction of the RFID tag element 100 is perpendicular to the direction from the tool 400 to the RFID reader, and the direction of the tool 400 is defined as 180° when the back radiation direction of the RFID tag element 100 faces the RFID reader. Figure 6 As shown, when the tool 400 is at 0° relative to the RFID reader, the maximum recognizable distance performance of the RFID tag element 100 is the best. When the tool 400 is rotated to 90° relative to the RFID reader, the maximum recognizable distance of the RFID tag element 100 decreases by 0.5 m, and when the tool 400 is rotated to 180° relative to the RFID reader, the maximum recognizable distance of the RFID tag element 100 decreases by another 0.5 m. However, this difference has little impact in actual application environments.

[0061] For tools or furniture made of different dielectric materials (such as wood and engineering plastics), RFID tag components are often embedded in the dielectric material when using RFID systems for asset management, loss prevention, access control, and maintenance management. The embedded installation method not only protects the RFID tag components from harsh environments, but also improves the appearance of the tools. However, since the RFID tag components may have a radiation gain preference in a specific direction, and its direction and position cannot be intuitively determined inside the tool, not all tools with embedded tags can face the reader when the RFID reader is used to read from the outside. Therefore, when identifying multiple tools in any direction, the uniform radiation gain characteristics of the RFID tag components are particularly important.

[0062] Figure 7The schematic diagram of the RFID tag element 200 of the fourth embodiment of the present invention being arranged in the tool 700 is shown. In this embodiment, the tool 700 is made of a dielectric material (such as wood or engineering plastic). The RFID tag element 200 can be arranged in an intermediate piece 710 first, and then the intermediate piece 710 and the RFID tag element 200 are inserted into the tool 700 together.

[0063] Figure 8 The radiation patterns of the RFID tag element 200 in the cross-sectional direction when the RFID tag element 200 according to the fourth embodiment of the present invention is inserted into the tool 700 at different angles are shown. Figure 8 The left side shows the Figure 7 A bottom view of the tool 700 as viewed from perspective A is shown in FIG. 1 , wherein the plane where the RFID tag element 200 is located ( Figure 2b The angles between the plane defined by the x-axis and the z-axis in the figure and the reference horizontal plane of the tool are 0°, 45° and 90° respectively. When the RFID tag element 200 is inserted into the tool 700 at 0°, 45° and 90° respectively, the ground plane of the RFID tag element 200 faces the RFID reader at the front, the inclined surface and the side surface respectively. Figure 8 As shown on the right side of , as the measurement results of the RFID tag element 200 inserted into the tool 700 at 0°, 45° and 90° respectively, when inserted at 45°, the spatial radiation gain is relatively high, but is different by about 0.1dBi compared to the cases of insertion at 0° and 90°. Figure 8 The measurement results shown in can indicate that in actual application environments, no large radiation deviation will occur with changes in the insertion angle.

[0064] Fig. 9 FIG. 2 shows the change in the recognizable distance performance of the RFID tag element 200 when the RFID tag element 200 of the fourth embodiment of the present invention is inserted into the tool 700 at different angles as the angle of the RFID tag element 200 changes. Fig. 9 As schematically shown in the upper left corner of FIG. 700 , the relative direction between the reference horizontal plane of the tool 700 and the RFID reader remains unchanged, while the insertion direction of the RFID tag element 200 in the tool 700 is changed, that is, the RFID tag element 200 is inserted around its longitudinal axis ( Figure 2a When the RFID tag element is placed in the tool 700 at 0°, 45° and 90° to the reference horizontal plane of the tool 700, the maximum recognizable distance performance does not change much. It can be seen that the RFID tag element proposed in the present application has uniform radiation characteristics in all directions.

[0065] Here, although Figure 7 to Figure 9The RFID tag element 200 is described and shown in the drawings, but it should be understood that it can also be set as follows Figure 1a to Figure 1b The RFID tag element 100 shown in FIG.

[0066] The present invention relates to a special RFID tag element that can improve the recognition rate of the RFID tag element by minimizing the difference between the forward radiation gain and the backward radiation gain of the RFID tag element, thereby making the recognition distance deviation in any direction relative to the tool to which the RFID tag element is attached or when a plurality of tools are arranged in any direction smaller.

[0067] As the use scenarios of RFID tags in various industrial fields expand, in addition to the readable identification distance of RFID tags in a static environment, the versatility of RFID tags that can cope with various environments and variables in actual application sites has also become very important. In particular, due to the inherent appearance characteristics of the object to which the RFID tag is attached, it is difficult to visually confirm the tag attachment position from the outside, or in order to protect the RFID tag from the influence of the external environment, and for the stability of the attachment, when the RFID tag is inserted into a specific space in the attached object, it is almost impossible to form the optimal identification state of the RFID reader antenna and the object to be identified. During the storage, movement or packaging of objects, especially in large warehouses, RFID tags are placed in any direction or on shelves at different heights. At this time, the omnidirectional recognition ability of the tag is the key to ensuring the stability of the RFID system. Therefore, when the RFID tag is installed at a higher position on the conductive shelf of a large warehouse, if its forward, backward and side radiation gains are similar, the use of an RFID reader on the ground can maintain a high recognition rate and flexibility. The technical solution provided by the present invention can reduce the scattering, interference and interference of radio waves when batch identifying multiple objects passing through the access control, and significantly improve the recognition performance of object tags in any direction or rotation direction.

[0068] The technical solution of the present invention aims to achieve complex impedance matching between the conductive medium and the tag chip, and reduce the size of the tag so that the tag has a ground plane, so that it can be widely used in objects with different dielectric constants, high dielectric liquids in specific containers, and conductive materials. In particular, the structural characteristics of this tag are constructed by using the stacked PCB manufacturing technology commonly used in electronic circuits, realizing the fine and standardized production of low-cost, universal tags.

[0069] The RFID tag element of the present invention forms a stacked structure by setting through holes at both ends to reduce the tag size, and controls the coupling capacitance with the bottom ground plane to adjust the complex impedance matching of the RFID tag element chip. This can be achieved by coupling the top layer and the middle layer with the bottom ground plane in a forked finger structure, or maintaining a certain distance. Such a structural design exposes the sensitive design variables for adjusting the center frequency of the RFID tag to the outside, making it easy to adjust the electrical performance of the RFID tag according to the changes and errors of the attached object. In addition, the chip of the RFID tag element is set in an embedded manner to form a low-profile shape, which not only reduces the risk of damage caused by the external environment, but also improves the aesthetics. In a multi-layer PCB structure, the spacing between different layers is an important design variable for the electrical performance of the RFID tag element and effective tag matching, providing a variety of adjustment possibilities.

[0070] Some exemplary embodiments are described above. However, it should be understood that various modifications may be made to the exemplary embodiments described above without departing from the spirit and scope of the present invention. For example, if the described techniques are performed in a different order and / or if the components in the described systems, architectures, devices, or circuits are combined in different ways and / or replaced or supplemented by other components or their equivalents, suitable results may be achieved, and these modified other implementations also fall within the scope of protection of the claims.

Claims

1. A radio frequency identification tag component, characterized in that: The RFID tag element has one end and another end along the length direction, and comprises: substrate; a first through hole, the first through hole being disposed in the substrate at one end of the RFID tag element; a second through hole, the second through hole being disposed in the substrate at the other end of the RFID tag element; A bottom layer, the bottom layer is located at the bottom of the substrate, one end of the bottom layer is close to one end of the RFID tag element and the other end of the bottom layer is close to the other end of the RFID tag element; an intermediate layer, the intermediate layer being located between the top and the bottom of the substrate, one end of the intermediate layer being electrically connected to one end of the bottom layer through the first through hole and the other end of the intermediate layer extending toward the other end of the RFID tag element; a top layer, the top layer being located on the top of the substrate, the other end of the top layer being electrically connected to the other end of the bottom layer through the second through hole, one end of the top layer being spaced apart from the first through hole, and the top layer having a gap; and a chip bonded to the top layer across a gap in the top layer, The distance between the other end of the intermediate layer and one end of the RFID tag element does not exceed the distance between the gap and one end of the RFID tag element.

2. The RFID tag component according to claim 1, characterized in that: The center frequency of the RFID tag element can be adjusted by adjusting the length of the top layer and / or the length of the middle layer.

3. The RFID tag component according to claim 1, wherein: The other end of the middle layer is aligned with a side of the gap close to one end of the top layer.

4. The RFID tag component according to claim 1, wherein: A projection of the middle layer on the bottom layer at least partially overlaps with a projection of the top layer on the bottom layer.

5. A radio frequency identification tag component, characterized in that: The RFID tag element has one end and another end along the length direction, and comprises: substrate; a first through hole, the first through hole being disposed in the substrate at one end of the RFID tag element; a second through hole, the second through hole being disposed in the substrate at the other end of the RFID tag element; A bottom layer, the bottom layer is located at the bottom of the substrate, one end of the bottom layer is close to one end of the RFID tag element and the other end of the bottom layer is close to the other end of the RFID tag element; an intermediate layer, the intermediate layer being located between the top and the bottom of the substrate, one end of the intermediate layer being electrically connected to one end of the bottom layer through the first through hole and the other end of the intermediate layer being connected to the other end of the bottom layer through the second through hole, and the intermediate layer having a gap; a chip bonded to the middle layer across a gap in the middle layer; A top layer is located on the top of the substrate, one end of the top layer is spaced apart from one end of the RFID tag element and the other end of the top layer is spaced apart from the other end of the RFID tag element, the top layer has a mechanical hole, the mechanical hole at least partially overlaps with the gap of the middle layer and accommodates the chip in the mechanical hole.

6. The RFID tag element according to claim 5, characterized in that: The gap is located at a middle position of the intermediate layer in a direction from one end of the intermediate layer to the other end of the intermediate layer.

7. The RFID tag element according to claim 5, characterized in that: A projection of the top layer on the bottom layer at least partially overlaps with a projection of the middle layer on the bottom layer.

8. The RFID tag component according to claim 5, characterized in that: The top layer is symmetrical with respect to a center line between one end and the other end of the RFID tag element.

9. The RFID tag component according to claim 5, characterized in that: The center frequency of the RFID tag element can be adjusted by adjusting the length of the top layer.

10. A tool, characterized in that: The tool has a surface to which the RFID tag element according to any one of claims 1 to 9 is attached.

11. The tool according to claim 10, characterized in that The surface has a recess for receiving the RFID tag element.

12. The tool according to claim 10, characterized in that The RFID tag element is mounted in the groove in such a manner that the bottom layer is close to the surface.

13. The tool according to claim 10, characterized in that The RFID tag component is mounted in the recess in such a manner that the top layer is adjacent to the surface.

14. The tool according to claim 13, characterized in that The chip of the RFID tag element is spaced apart from the surface.

15. A tool, characterized in that: The tool has a cavity therein configured to accommodate the RFID tag component according to any one of claims 1 to 9, and the RFID tag component is disposed in the cavity along a length direction.

16. The tool according to claim 15, characterized in that The RFID tag element is disposed in the cavity in a direction in which its length direction is parallel to the axial direction of the tool.

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