RFID tags with improved antenna characteristics

Abstract

The present invention relates to an electronic device (1) configured to communicate with radio frequency signals, the electronic device (1) comprising a chip, a first antenna, and a second antenna (2), the second antenna (2) configured to form an electromagnetic coupling with the first antenna, the second antenna (2) configured to facilitate radio frequency communication, and comprising a core (3) including a plurality of yarns (4.1, 4.2) and a pair of protective yarns (5) wound around the core (3).

Description

Technical Field

[0001] Technical Field of the Invention The present invention relates to a device comprising means for detecting and emitting electromagnetic radiation and a corresponding antenna suitable for mounting on a tire. More specifically, the electromagnetic radiation is in the radio frequency range, and the device comprises an RFID tag provided with a yarn (or thread) configured to conduct an electrical signal, and a tire provided with the same.

Background Art

[0002] Background of the Invention It is known that incorporating an electrical device into a tire structure has many advantages during manufacturing, transportation, and storage, such as tracking the tire, and measuring and recording physical parameters such as temperature and pressure. For these purposes, various types of electrical devices are used in this technical field, but radio frequency communication between the tire and an external monitoring device or interrogating device is the most common. Such a communication system often comprises a radio frequency identification (RFID) tag and a reader that communicates with the RFID tag. The RFID tag comprises an antenna and an RFID chip. Thus, information from the reader is received via the antenna and stored in the RFID chip. The information stored in the RFID chip is transmitted to the reader via the antenna. The RFID device can be a read-only, write-only, or read-write device.

[0003] RFID tags and corresponding antennas are widely used in various applications including tires. In recent years, attaching an RFID tag to the inside or the surface of a tire has become a common practice. The problems commonly faced in such applications can be summarized as low backscatter performance, manufacturing difficulties, and short read range. Also, the size of the tag antenna becomes an issue. In this case, if the size of the antenna exceeds a predetermined length, it becomes difficult to attach it to the tire.

[0004] Prior art documents in the technical field of the present invention include, among others, WO2017060222A1 (Patent Document 1), which discloses an antenna for use in RFID tags. The antenna yarn contains metal fibers. The metal fibers are stainless steel fibers. The antenna yarn is wound with at least one wrapping yarn, thereby covering the entire surface of the antenna yarn, metal wire, or bundle of metal wires. This at least one wrapping yarn contains non-conductive fibers.

[0005] Prior art documents in the field of the present invention include, among others, EP4063544A1 (Patent Document 2), which discloses a composite yarn for supporting electronic components and a method for manufacturing the same. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] WO2017060222A1 [Patent Document 2] EP4063544A1 [Overview of the project] [Problems that the invention aims to solve]

[0007] The objective of the present invention is to manufacture an RFID tag equipped with an antenna, which facilitates the manufacturing process of the RFID tag and the manufacturing process of the RFID tag's antenna.

[0008] Another object of the present invention is to improve the signal strength of the antenna, thereby increasing the reading distance of the antenna.

[0009] Another object of the present invention is to optimize the length of the antenna according to the requirements of different types of tires.

[0010] A further objective of the present invention is to improve the signal quality of the antenna by maximizing backscattering.

[0011] Another object of the present invention is to provide a unit equipped with a highly durable RFID tag and antenna. [Means for solving the problem]

[0012] To achieve the objectives of the present invention, the methods disclosed in the first and dependent claims comprise an electronic device (or electronic device) capable of communicating via radio frequency signals. In a preferred embodiment of the present invention, the electronic device is an RFID tag. The device comprises an antenna for amplifying the signal to facilitate communication, the antenna comprising a core mainly composed of several yarns twisted together. Thus, the core is covered with a pair of protective yarns (or protective yarns or protective threads) that completely enclose the core. The core comprises a first yarn made of aramid fiber and a second yarn made of a metallic material. In a preferred embodiment, the metallic material is steel, but those skilled in the art can apply other metallic materials available for such applications. The combination of aramid fiber and a metallic wire, more preferably a steel wire, achieves higher signal strength. Furthermore, it provides a longer reading distance compared to conventional systems. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a perspective view of an electronic device. [Figure 2] Figure 2 is a perspective view of the core and protective yarn. [Figure 3] Figure 3 is a perspective view of the antenna. [Figure 4] Figure 4 shows the cross-sectional area of ​​the antenna along the dashed line AA in Figure 3. [Modes for carrying out the invention]

[0014] In a preferred embodiment of the present invention, the dtex (or decitex or total fineness) value of the first yarn is 400 to 700. In the most preferred embodiment of the present invention, the dtex value of the first yarn is 670. On the other hand, the second yarn contains 250 to 300 filaments, more preferably 270 to 280 filaments, and even more preferably 275 filaments. This range of filament count, more specifically 275 filaments, provides improved signal strength.

[0015] In a preferred embodiment of the present invention, the second yarn has 50 to 200 TPM, more specifically 100 TPM. TPM is a twist-per-meter value commonly used for yarn.

[0016] In a preferred embodiment of the present invention, the first yarn and the second yarn are twisted together at 200-300 TPM, more preferably 235 TPM. This TPM range and value provides optimal signal strength while simultaneously preventing breakage of the metal filaments.

[0017] In a preferred embodiment of the present invention, the protective yarn is twisted to a thickness of 75-250 TPM, more preferably 90-200 TPM, and even more preferably 100 TPM. The dtex value of the protective yarn is 450-500. This dtex value ensures that the protective yarn is thick enough to protect the core from external elements. Furthermore, the protective yarn is wound around the core to a thickness of 1000-1400 TPM. One end of the protective yarn is Z-twisted and the other end is S-twisted. In another embodiment, the twist directions of the protective yarn may be the same.

[0018] In a preferred embodiment of the present invention, the antenna is primarily coated with an RFL solution and secondarily (or supplementarily) coated with a tackifying solution.

[0019] In a preferred embodiment of the present invention, the electronic device is suitable for use within a tire.

[0020] According to the present invention, ease of manufacture, high backscattering characteristics, and long reading distances are achieved. Furthermore, signal strength is improved, and more powerful embodiments of antennas and RFID tags are realized.

[0021] The drawings do not limit the scope of protection specified in the claims, and neither should the drawings alone be relied upon to interpret the scope specified in the claims without relying on the technical disclosure in the description of the present invention.

[0022] Detailed Description of the Invention The present invention relates to an electronic device (1) configured to communicate radio frequency signals, the electronic device (1) comprising a chip, a first antenna, and a second antenna (2), the second antenna (2) being configured to form an electromagnetic coupling with the first antenna, the second antenna (2) being configured to facilitate communication of radio frequency signals, and comprising a core (3) including a plurality of turns (4.1, 4.2) and a pair of protective turns (5) wound around the core (3).

[0023] The present invention further comprises a core (3) in which a first yarn (4.1) made of aramid and a second yarn (4.2) made of steel are twisted together. The electronic device (1) may be an identification device or a tracking device and can be used to record the manufacturing, distribution, sales activities, temperature measurement, pressure measurement, or other physical characteristics of a tire while it is in operation. Furthermore, the electronic device (1) can be used to measure parameters while the tire is in storage. In a preferred embodiment of the present invention, the electronic device (1) is an RFID transponder, the RFID transponder comprising a chip and an antenna (2), the antenna (2) configured to facilitate communication with an RFID reader, the reader provided as an external component. The antenna (2) comprises a core (3), the core (3) having an elongated shape to facilitate the transmission of radio waves and thus data packages, and comprising a pair of yarns (4.1, 4.2). The first yarn (4.1) is made of aramid fiber, and the second yarn (4.2) is made of metal, more preferably steel. Those skilled in the art will understand that any metal known to enhance signal strength in such applications can be used. For example, the second yarn (4.2) may consist of copper, aluminum, titanium, or silver. The first and second yarns (4.1, 4.2) are Z-twisted and S-twisted. In further embodiments, the first and second yarns are S-twisted and Z-twisted. The twisting of these yarns (4.1, 4.2) achieves a spring effect, thereby reducing the possibility of core (3) breakage. Furthermore, the yarns (4.1, 4.2) are twisted together. These yarns can be twisted together in a Z-twist or S-twist, which promotes (or aids) the interconnection of the yarns (4.1, 4.2). The first yarn (4.1) is made of aramid fiber, and the second yarn (4.1) is made of metal wire, more preferably steel wire, which improves signal transmission strength and provides better backscattering characteristics. This combination also provides a longer reading distance.These yarns (4.1, 4.2) are then covered with protective yarns (5), in a preferred embodiment, of which there are two protective yarns (5). As the name suggests, the protective yarns (5) provide a protective layer around the core (3), i.e., the first and second yarns (4.1, 4.2), and isolate these yarns (4.1, 4.2) from the environmental conditions and chemicals into which the antenna (2) will subsequently be immersed.

[0024] In a preferred embodiment of the present invention, the dtex value of the first yarn (4.1) is 400 to 700. When the dtex value exceeds 700, the radius of the core (3) and consequently the radius of the antenna (2) become too large, exceeding the acceptable limit, so this range was found to be the most optimal.

[0025] In preferred embodiments of the present invention, the second yarn (4.2) comprises 250 to 300 filaments, more preferably 270 to 280 filaments, and even more preferably 275 filaments. The second yarn (4.2) comprises multiple metallic filaments. In one embodiment, the number of filaments is 250 to 300 to provide good signal strength. In another embodiment, the number of filaments is 270 to 280. These ranges are important to ensure good signal strength while keeping the thickness of the core (3) to a minimum, thereby preventing the core (3) from being recognized as a large foreign object inside the tire and achieving good adhesion of the antenna (2) and electronic device (1) to the tire surface or interior. Experiments have shown that 275 filaments is the optimal choice because it provides good adhesion of the electronic device (1) to the tire while keeping the thickness of the antenna (2) to a minimum, while providing excellent signal strength, long reading distance, and high backscatter performance.

[0026] In a preferred embodiment of the present invention, the second yarn (4.2) has 50 to 200 TPM, more preferably 100 TPM. TPM refers to the number of turns per meter of yarn. 50 to 200 TPM, more preferably 100 TPM, provides an excellent RSSI value. Within this TPM range, the RSSI value decreases, achieving better signal strength. In other words, the signal strength improves by -50 dB ± 1 dB, where dB represents decibels.

[0027] In a preferred embodiment of the present invention, the yarns (4.1, 4.2) are twisted together at a TPM of 200-300, more preferably 235 TPM. The TPM values ​​of the yarns (4.1, 4.2) relative to each other are extremely important for providing excellent fatigue resistance and conductivity. Therefore, in a preferred embodiment, the TPM value is in the range of 200-300 TPM, but more preferably 235 TPM. It has been found that 235 TPM is the optimal value for providing good fatigue resistance and conductivity. Another point to consider is the fact that high TPM values, for example, above 400 TPM, increase the likelihood of metal (steel in this case) filament breakage.

[0028] In a preferred embodiment of the present invention, the protective yarn (5) has a TPM of 75 to 250, more preferably 90 to 200, and even more preferably 100. The TPM of the protective yarn (5) around the core (3) must be less than 200. If the number is higher, a problem arises in which gaps will form between the protective yarns (5). As a result, the solution may leak into the core (3) of the antenna (2), damaging the core (3) or reducing the signal strength. In a preferred embodiment of the present invention, one end of the protective yarn (5) is Z-twisted and the other end is S-twisted. By using S-twisted and Z-twisted yarns, the core (3) is safely and completely surrounded.

[0029] The TPM of a pair of protective yarns (5) is 100 TPM for each of them.

[0030] In a preferred embodiment of the present invention, the dtex value of the protective yarn (5) is 450 to 500. The dtex value of the protective yarn (5) is important because, at high values ​​exceeding 500, the antenna (2) becomes excessively thick and is affected by foreign body behavior. As a result of this behavior, the electronic device (1) may detach from the tire. Furthermore, a high dtex value increases the thickness and weight of the electronic device (1). This exacerbates the problem of foreign body behavior inside the tire. Experimentally, it has been observed that the optimal dtex value for the protective yarn (5) is 450.

[0031] In a preferred embodiment, the protective yarn (5) is made of nylon.

[0032] In a preferred embodiment of the present invention, the protective yarn (5) is wound around the core (3) at a rate of 1000 to 2000 TPM. The above TPM values ​​are selected to protect the second yarn (4.2) from the external environment, thereby extending the service life of the electronic device (1). In a preferred embodiment, the protective yarn (5) is wound around the core (3) at a rate of 1000 to 1400 TPM. Experimentally, it has been observed that the optimal TPM is 1300 ± 6%.

[0033] In a preferred embodiment of the present invention, the antenna (2) is primarily coated with an RFL solution. In an alternative embodiment, a resorcinol formaldehyde-free (RF-free) composition can be used, such as a composition containing an acrylic resin or natural latex. In an alternative embodiment, a rosin ester and / or a rosin ester tackifier may be added to the immersion solution. The solution may be aqueous or organic solvent-based. The organic solvent is selected from the group including toluene, hydrocarbon solvents, xylene, ethyl acetate, alcohols, ethers, and mixtures thereof. The tackifier solution is then applied to the antenna (2) and allowed to dry. However, those skilled in the art will understand that any method known in the art for improving the adhesion of the component to rubber can be used in this application. The ultimate goal is to ensure that the antenna (2) remains intact and adhered to or inside the tire for the entire lifespan of the tire.

[0034] In a preferred embodiment of the present invention, the electronic device (1) is used in a tire. Types of tires on which the electronic device (1) can be mounted include, but are not limited to, bias tires, belt bias tires, radial tires, solid tires, semi-pneumatic tires, pneumatic tires, and airless tires. The electronic device (1) can be directly attached to the rubber before the curing process, or embedded between layers including the final tire product. Alternatively, the electronic device can be mounted at any suitable location within the tire.

[0035] The advantageous effect provided by the present invention is that the structure of electronic devices is simplified, making them easier to manufacture, and consequently reducing manufacturing-related costs.

[0036] Another advantage provided by the present invention is high backscattering performance. Furthermore, another advantage obtained by the present invention is a longer reading distance compared to antennas manufactured according to conventional methods.

[0037] Another advantageous effect provided by the present invention is to provide an electronic device (1) equipped with an antenna (2) with improved durability and strength.

[0038] Another advantageous effect obtained by the present invention is that the signal strength of the electronic device (1) is improved. [Explanation of symbols]

[0039] The following numbers are assigned to various parts shown in the drawings and referenced in the detailed description of the invention. 1. Electronic devices 2 antennas 3 cores 4 yarns 4.1 The First Yarn 4.2 The second yarn 5. Protective yarn

Claims

1. An electronic device (1) configured to communicate radio frequency signals, It comprises a chip, a first antenna, and a second antenna (2), The second antenna (2) is configured to form an electromagnetic coupling with the first antenna, and the second antenna (2) is configured to facilitate the communication of radio frequency signals and includes a core (3) comprising a plurality of yarns (4.1, 4.2) and a pair of protective yarns (5) wrapped around the core (3). The electronic device (1) is characterized in that the core (3) comprises a first yarn (4.1) made of aramid and a second yarn (4.2) made of metal, and these yarns (4.1, 4.2) are twisted together.

2. The electronic device (1) according to claim 1, characterized in that the dtex value of the first yarn (4.1) is 400 to 700.

3. The electronic device (1) according to claim 1, characterized in that the second yarn (4.2) contains 250 to 300 filaments, more preferably 270 to 280 filaments, and more preferably 275 filaments.

4. The electronic device (1) according to claim 1, characterized in that the second yarn (4.2) has 50 to 200 TPM, more preferably 100 TPM.

5. The electronic device (1) according to claim 1, characterized in that the yarns (4.1, 4.2) are twisted together at a rate of 200 to 300 TPM, more preferably at a rate of 235 TPM.

6. The electronic device (1) according to claim 1, characterized in that the protective yarn (5) has a density of 75 to 250 TPM, more preferably 90 to 200 TPM, and more preferably 100 TPM.

7. The electronic device (1) according to claim 1, characterized in that the dtex value of the protective yarn (5) is 450 to 500.

8. The electronic device (1) according to claim 1, characterized in that the protective yarn (5) is wound around the core (3) at a rate of 1,000 to 1,400 TPM.

9. The electronic device (1) according to claim 1, characterized in that the antenna (2) is mainly coated with an RFL solution.

10. The electronic device (1) according to claim 9, characterized in that the antenna (2) is auxiliaryly coated with an adhesive solution.

11. The electronic device (1) according to claim 10, characterized in that the adhesive solution comprises at least one material selected from the group consisting of resorcinol formaldehyde latex solution, acrylic resin solution, rosin ester solution, natural latex solution, and combinations thereof.

12. A tire having an electronic device (1) according to any one of claims 1 to 11.

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