RU2811529C1 - Rfid tag for rubber products and production method of rfid tag for rubber products - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: RFID tag for rubber products and to a method for producing an RFID tag for rubber products. RFID tag for rubber products 1 has coupling transformer 40, RF chip 10 connected to the secondary side of the communication transformer, printed circuit board 20 on which the RF chip is mounted, and antenna 30, the antenna having coil portion 31, first element 32, extended at one end of the coil portion, and second element 33 shorter than the first element extended at the other end of the coil portion in parallel with the first element, and the number of turns of the coil portion is less than the number of turns on the secondary side of coupling transformer 40, and also the coil portion part forms the primary side of the coupling transformer by holding the printed circuit board in the gap between the turns of the core of the coil part.

EFFECT: compact and durable RFID tag for rubber products.

7 cl, 9 dwg

Description

[Technical field]

[0001]

This invention relates to an RFID tag for rubber products that is compact, suitable for mass production and durable, and a method for producing an RFID tag for rubber products.

[Technique level]

[0002]

The RFID tag used in the Radio Frequency Identification (RFID) system contains an antenna and an RF chip, providing a contactless communication function in which the carrier wave transmitted from the antenna of the reader and writer is received by the antenna, then the identification data and etc., recorded in the RF chip, are transmitted back via a reflected wave to the reader and writer.

By sticking an RFID tag on a tire or implanting it into a tire for cars or other types of wheeled vehicles, it becomes possible to manage the tire's unique information, as well as the history of production, logistics, maintenance, etc. When sticking an RFID tag on other rubber products or By implanting it in them, of course, you can also control these products.

[0003]

The RFID tag-embedded tires of Patent Document 1 have a first antenna coupled to the IC chip and a second antenna coupled to the first antenna by electromagnetic coupling, and this patent document discloses a technology for electromagnetic coupling of the second antenna with electrically conductive cords in the carcass layers. .

[Prior Art Documents]

[Patent documents]

[0004]

[Patent Document 1] Unexamined Official Gazette Patent No. 2017-132291

[Essence of the invention]

[Problem solved by the invention]

[0005]

In case the tires are equipped with an RFID tag, there may be a problem of damage to the RFID tag due to the deformation of the tires while the vehicle is moving. In addition, when free electrons in the carbon black contained in the tires receive radio waves, the charge of the electron changes from negative to positive, causing current to flow from the positive to the negative pole, thereby causing the problem of changing impedance and relative permittivity.

In the invention of Patent Document 1, the first and second antennas are connected through electromagnetic coupling, and the impedance of the signal source on the second antenna is high, so that it, when influenced by carbon black, is easily affected by changes in impedance and relative permittivity.

Since the second antenna has a pair of parts extended to the left and right of the electromagnetic coupling point, when the tire is deformed, the right and left extended parts may be pulled in the right and left directions around the electromagnetic coupling point, resulting in damage.

[0006]

In addition, the existing RFID tag using a half-wave dipole antenna has the problem of large size, as well as the problem of difficulty in determining the effective meander length under the influence of carbon black, even if a meander antenna compacted by bending the antenna element is used.

The above-mentioned problems may also arise in cases where the RFID tag is used in rubber products other than a tire, in particular in rubber products containing materials that affect the communication performance of the RFID tag, such as carbon black.

[0007]

An object of the present invention is to provide an RFID tag for rubber products that is compact, suitable for mass production, and durable, as well as a manufacturing method for an RFID tag for rubber products, taking into account some of the above-mentioned problems.

[Tool for solving the problem]

[0008]

The RFID tag for rubber products of the present invention is characterized in that it has a communication transformer, an RF chip connected to the secondary side of the above communication transformer, a printed circuit board on which the above RF chip is mounted, and an antenna, wherein the above antenna has a coil part, a first element extended from one end of the above-mentioned coil portion, and a second element shorter than the first element extended from the other end of the above-mentioned coil portion in parallel with the above-mentioned first element, and the number of turns of the above-mentioned coil portion is less than the number of turns on the secondary side of the above communication transformer, as well as the above-mentioned coil part forms the primary side of the above-mentioned communication transformer by holding the above-mentioned printed circuit board in the gap between the turns of the core of the above-mentioned coil part.

In addition, the RFID tag is different in that it is designed for rubber products containing carbon black and

in that the printed circuit board has insulating layers on the front and back surfaces, and

in that the coil portion, the first element and the second element are formed by one wire, and

Moreover, the axis of the inductor coil of the secondary side of the coupling transformer coincides with the axis of the coil part, and

in that if the length of radio waves at the radio frequency is λ, the electrical length of the unit consisting of the first element, the second element and the coil part is equal to λ/4.

[0009]

The manufacturing method of the RFID tag for rubber products of the present invention is characterized in that it has the step of placing multiple secondary side inductors of a communication transformer in the left-right direction on the printed circuit board, the step of opening slots in front and behind the above-mentioned multiple secondary side inductors placed in the left direction. -right direction, and a notch processing step between the above-mentioned multiple secondary side inductors placed in the left-right direction.

The manufacturing method in question is also different in that there is also a step in which the above-mentioned coil part is made the primary side of the communication transformer by inserting the above-mentioned secondary side inductor into the gap between the turns of the core of the above-mentioned coil part through the above-mentioned front slot using an antenna having a coil part, a first element extended from one end of the above-mentioned spool part, and a second element shorter than the first element extended from the other end of the said spool part in parallel with the above-mentioned first element.

[Invention Effect]

[0010]

In the case of the RFID tag for rubber products of the present invention, the communication transformer is formed by holding the printed circuit board in the gap of the coil part. Thus, the mass production suitability of the RFID tag for rubber products can be improved.

In addition, according to the present invention, the first and second elements functioning as an antenna are extended in parallel, which reduces the risk of damage to the RFID tag with increased durability and allows for an RFID tag that is more compact than the existing half-wave dipole antenna.

Moreover, according to the present invention, the number of turns of the coil portion serving the primary side is reduced to less than the number of turns of the inductor of the secondary side so that the impedance at the input of the primary side becomes low and the impedance at the input of the secondary side is converted to high by using a coupling transformer for matching. it with the input impedance of the RF chip. The reduced primary side impedance reduces the impact of carbon black, for example, when the RFID tag is used in rubber products containing carbon black, etc.

The front and back surfaces of the printed circuit board are made with insulating layers to avoid electrical connection of the coil part with the secondary side inductor.

The coil part, the first element and the second element are formed by bending one wire, which facilitates the manufacture of the antenna, and also improves the reliability of the electrical connection between the coil part, the first and second elements.

The coincidence of the axis of the inductor coil of the secondary side of the coupling transformer with the axis of the coil part ensures increased efficiency of the coupling transformer.

Setting the electrical length of the assembly, consisting of the first element, the second element and the coil part, equal to λ/4, allows us to minimize the length of the antenna and thereby further compact the RFID tag for rubber products.

[0011]

By the production method of the RFID tag for rubber products of the present invention, the secondary side inductor coil can be easily inserted into the gap of the coil part through the front slot, which provides improved production efficiency.

By notching between the secondary side inductors and the front and rear notches, a PCB of the specified size can be easily obtained.

[Brief description of drawings]

[0012]

[Fig. 1] Top view (a), bottom view (b), side view (c), modified example (d) and modified example (e) of the antenna.

[Fig. 2] Top view (a) showing the condition of the RF chip and secondary side inductor installed on the PCB, top view (b), bottom view (c) and side view (d) showing the condition of the sealed RF chip and seats connections.

[Fig. 3] Top view (a), bottom view (b) and side view (c) showing the condition before inserting the PCB into the gap of the coil part.

[Fig. 4] Top view (a), bottom view (b) and side view (c) showing the condition after inserting the printed circuit board into the gap between the turns of the coil part.

[Fig. 5] Equivalent circuit of RFID tag for rubber products.

[Fig. 6] Longitudinal sectional view showing the condition of the front and back surfaces of an RFID tag for rubber products covered with rubber sheets.

[Fig. 7] Longitudinal sectional view showing the condition of the RFID rubber tag installed on the tire.

[Fig. 8] Top views (a) - (c) showing the manufacturing method of RFID tag for rubber products.

[Fig. 9] Top views (a) and (b) showing the manufacturing method of RFID tag for rubber products.

[Description of embodiments of the invention]

[0013]

Embodiments of the present RFID tag invention for rubber products are explained using drawings.

As shown in FIG. 1 - Fig. 4, the RFID tag for rubber products 1 has an RF chip 10, a circuit board 20, an antenna 30 and a communication transformer 40. For further explanation, the RFID tag for rubber products 1 may be referred to more simply as "RFID tag 1".

[0014]

The RF chip 10 is connected to the secondary side of the coupling transformer 40 mentioned below. Standard commercial products can be used as the RF chip 10, but it is desirable to use a product that can withstand a vulcanization temperature of about 120°C.

As shown in FIG. 2(a), an RF chip 10 is mounted on the front surface of the printed circuit board 20 using an adhesive such as an epoxy-based Dye Bond material.

Next, a secondary side inductor 41 of the coupling transformer 40 is formed on the front surface of the printed circuit board 20. One of the two contacts of the secondary side inductor 41 is connected to a contact of the RF chip 10 by a wire connection. As shown in FIG. 2 (a) and (c), the other contact of the secondary side inductor 41 passes through the through hole 21 to the back surface of the printed circuit board 20 and then through the through hole 22 to the front surface of the printed circuit board 20, where this contact is connected to the RF chip contact 10 wire connection. In the present embodiment, the number of turns of the secondary side inductor 41 is about 4 (actually 3.96). The secondary side inductor 41 may be a coil made of wire, not limited to a flat-shaped coil that is formed by a vapor deposition method or the like. As shown in FIG. 2(b), it is desirable that the RF chip and the connections are sealed with an insulating layer 27.

As shown in FIG. 2 (d), the front surface of the printed circuit board 20, i.e. The front surface of the RF chip 10 and the inductors of the secondary side 41 are sealed with an insulating layer 23. The reverse surface of the printed circuit board 20 is also sealed with an insulating layer 23. Insulating resins, such as epoxy, acrylic synthetic (resins containing mainly acrylic resins and their derivatives), urethane, etc.

[0015]

The antenna 30 is designed to receive a carrier wave from the reader and writer, and also to transmit the reflected wave back to the reader and writer.

The antenna 30 has a coil portion 31, a first element 32 and a second element 33. The core material for the antenna 30 can be copper, iron, brass and other metal wires.

[0016]

The coil portion 31 functions as the primary side of the coupling transformer 40. The number of turns of the coil portion 31 must be less than the number of turns on the secondary side. In the present embodiment, the number of turns of the core is 1.5, and a gap 31a is formed between the turns of the core. In the state of no external force being applied to the coil portion 31, the space between the turns of the core is naturally open, which can be considered a gap 31a, or as shown in FIG. 1(d), in the case of almost close contact of the windings with each other in the state of no external force applied to the bobbin part 31, it is possible to apply an external force to the bobbin part 31 in the vertical direction (in the axis direction) and elastically open the space between the winds of the strand , which is considered to be gap 31a. It is desirable that the diameter of the coil portion 31 in plan view should be equal to or slightly larger than the outer diameter of the secondary side inductor 41.

[0017]

The first element 32 is a component extended from one end of the bobbin portion 31. When the radio wavelength at the radio frequency of the RFID tag 1 is λ, it is desirable to set the electrical length of the first element 32 to one of λ/4, λ/2, (3/4 ) λ, (5/8) λ, since this can ensure that the resonant frequency of the first element 32 coincides with the radio communication frequency of the RFID tag 1, equal to λ.

The second element 33 is a component shorter than the first element 32 and extended at the other end of the spool portion 31 in parallel with the first element 32.

As, for example, by setting the electrical length of the first element 32 to be approximately 0.185 of the radio wavelength λ, and the same parameter of the second element 33 to be approximately 0.046 of the radio wavelength λ, and the length of the first element 32, the second element 33 and the coil portion 31 in total equal to approximately λ/4, the antenna length can be almost minimized to 30.

[0018]

According to the present embodiment, the coil portion 31, the first element 32 and the second element 33 are formed by bending a single wire, which facilitates the manufacture of the antenna 30 and thereby improves the reliability of electrical connections between the coil portion 31, the first element 32 and the second element 33. Without limitation As stated above, it is possible to form the antenna 30 by connecting the ends of several wires.

If the ends of the first element 32 and the second element 33 are bent as shown in FIG. 1(e), in the case of installing the RFID tag 1 on the rubber products, it can be prevented that the ends of the first 32 and the second members 33 pierce or cut the rubber products and the RFID tag 1 is damaged.

[0019]

As shown in FIG. 3 and Fig. 4, the coil part 31 forms the primary side of the coupling transformer 40 by holding the printed circuit board 20 in the gap 31a between the turns of the core of the coil part 31. It is desirable to ensure that the axis of the coil part 31 coincides with the axis of the inductor of the secondary side 41. The front and reverse surfaces of the printed circuit board 20 are sealed insulating layers 23 to avoid electrical connection between the coil part 31 and the inductor of the secondary side 41. In addition, the place between the turns of the core of the coil part 31, where the printed circuit board 20 is not inserted, is naturally insulated for the purpose of maintaining the function of the electric inductor.

[0020]

Fig. 5 is an equivalent circuit in the case where the RFID tag 1 is installed on a tire or other rubber product. When a signal is received, the radio waves received by the first element 32 and the second element 33 are transmitted to the RF chip 10 through the coupling transformer 40. Specifically, the first element 32 and the second element 33 carry a current in the inverted phase of the radio waves, and the coil portion of the primary side 31 current flows and an alternating current voltage is induced in the secondary side inductor 41.

In this case, the impedance of the RF chip 10 ranges from several kΩ to 10 kΩ, and the impedance between the first element 32 and the second element 33 is insignificant, amounting to only about 100 Ω. The insignificance of the impedance between the first element 32 and the second element 33 is largely due to the influence of a resistive element such as carbon black contained in rubber products, in addition to the impedance of the antenna 30 itself. Vulcanized rubber tires have a resistivity of the order of several tens of kΩ⋅cm, depending from species. In case the RFID tag 1 of the present invention is implanted in a vulcanized rubber tire by directly connecting both contacts of the RF chip 10 to the first element 32 and the second element 33, it is impossible to effectively transmit the received radio waves to the RF chip 10.

[0021]

Therefore, on the RFID tag 1 of the present invention, the ratio n (n=N2/N1) between the number of turns N2 on the secondary side and the number of turns N1 on the primary side of the coupling transformer 40 is adjusted. Specifically, in the case that the RF chip 10 with an input impedance Z is connected to the first element 32 and the second element 33 through a coupling transformer 40, the primary side impedance of the coupling transformer 40 being Z/n ² . Therefore, the primary side input impedance is reduced by increasing the value of n by reducing the number of turns N1 of the primary side coil portion 31 to less than the number of turns N2 of the secondary side inductor 41, and converts the secondary side input impedance to high using the coupling transformer 40 so as to match the input impedance Z of the RF chip 10. Even in the case that, for example, the RFID tag 1 is used in rubber products containing carbon black, etc., the influence of carbon black, etc. can be limited. by reducing the impedance of the primary side.

However, when increasing the number of turns N2 of the secondary side, there are limitations due to the area of the coupling transformer 40, etc., so it is desirable to adjust the ratio of the number of turns n on the secondary side and the primary side depending on the characteristics of the RF chip 10, the material of the rubber products, the volume of content carbon black, etc.

[0022]

The antenna 30 of the RFID tag 1 will operate similarly to the monopole antenna 30, where the second element 33 will be a Ground Plane antenna and the first element 32 will be an antenna wire. By gluing or implanting the RFID tag 1 into the vulcanized rubber product, there is the advantage that the Ground Plane antenna is further strengthened by electrically connecting the second element 33 and the vulcanized rubber product.

In addition, on the existing dipole antenna type RFID tag, 2 antenna elements with an electrical length of λ/4 are extended from the circuit board equipped with the RF chip in the left-right direction. In this design, however, if the rubber products are deformed, resulting in a force acting in opposite directions being applied to the two antenna elements, there is a risk of damage to the junction of the antenna elements with the printed circuit board. Compared with this, the RFID tag 1 of the present invention has the advantage that the junction of the base of the first element 32 or the second element 33 and the printed circuit board 20 is not easily disturbed and can be compacted since the first element 32 and the second element 33 are extended in parallel in the same direction.

[0023]

As shown in FIG. 6, it is possible to cover the front and back surfaces of the RFID tag 1 for rubber products with rubber sheets 50 and 51. Specifically, it is possible to produce the RFID tag 1 covered with rubber sheets by placing the RFID tag 1 between the first rubber sheet 50 and the second rubber sheet 51 followed by gluing the first rubber sheet 50 and the second rubber sheet 51 by pressing.

As materials for the rubber sheets 50 and 51, ordinary natural rubber and various types of synthetic rubber, as well as butyl rubber sheets and other adhesive materials can be used. Coating the RFID tag 1 with rubber sheets 50 and 51 allows the parts composing the RFID tag 1 to be protected from damage or displacement of their relative position even when the rubber products are deformed, and also makes the RFID tag 1 waterproof and dustproof.

[0024]

Fig. 7 shows the state of a rubber-coated RFID tag 1 adhered to the inner surface of the tire 60 as an example of rubber products. There are no particular restrictions on the places where the RFID tag 1 can be glued. It is allowed to stick the RFID tag 1 on the inner surface of the tire 60 or implant it into the rubber of the tire 60, and also stick the RFID tag 1 without rubber coatings onto the inner surface of the tire 60 or implant it into the tire 60 .

Installation of the RFID tag 1 on the bus 60 provides electrical connection of the second element 33 to the bus 60, whereby the bus 60 functions as a ground for the RFID tag 1. Therefore, the RFID tag 1 of the present invention can perform highly sensitive transmission even when installed on rubber products, such as tire 60. In this case, the connection of the second element 33 and the tire 60 can be achieved using either a capacitive connection or a direct connection.

[0025]

The following describes the production method of RFID Tag 1 for rubber products.

As shown in FIG. 8(a), first of all, several inductors of the secondary side 41 of the coupling transformer 40 in the left-right direction are placed on the circuit board 20 (Step A).

Then, as shown in FIG. 8(b), in front and behind several inductors of the secondary side 41 are opened by slots 24 and 25 (Step B). In this case, it is necessary to ensure that the distance between the front slot 24 and the rear slot 25 matches the length of the RFID tag 1 in the anterior-posterior direction.

Next, as shown in FIG. 8(c), make cuts 26 between several secondary side inductors 41 (Step C). In this case, it is necessary to ensure that the interval between cuts 26 coincides with the length of the RFID tag 1 in the left-right direction.

Steps A to C can be completed in any order. At the appropriate time, it is necessary to connect the RF chip 10 to the secondary side inductor 41, after which it is recommended to cover the surface of the RF chip 10 connected to the secondary side inductor 41 with an insulating layer 27.

[0026]

Next, as shown in FIG. 9(a), through the front slot 24, a secondary side inductor 41 is inserted into the gap between the turns of the core 31a of the coil portion 31. Due to this, the coil portion 31 functions as the primary side of the coupling transformer 40. In this case, placing the first element 32 and the second element 33 on the side edge 28 of the front slot 24, it is possible to move the coil part 31 towards the secondary side inductor 41 by a creeping motion on the surface of the side edge 28. Moreover, in a state where the secondary side inductor 41 is inserted into the core gap 31a, the first member 32 is placed on the side edge 28, which eliminates the risk of the antenna 30 falling out of the printed circuit board 20. If necessary, the coil part 31 can be glued to the printed circuit board 20.

Finally, as shown in FIG. 9(b), the production of the RFID tag 1 for rubber products is completed by cutting the printed circuit board 20 along the notch 26.

[Industrial applicability]

[0027]

The present invention relates to an RFID tag for rubber products, which is compact, suitable for mass production and durable, and a method for producing the RFID tag, and also has industrial applicability.

[Explanation of designators]

[0028]

1. RFID tag for rubber products

10. RF chip

20. Printed circuit board

21. Through hole

22. Through hole

23. Insulation layer

24. Front slit

25. Back slit

26. Incision

27. Insulation layer

28. Side edge

30. Antenna

31. Reel part

31a. Gap

32. First element

33. Second element

40. Communication transformer

41. Secondary side inductor

50. First rubber sheet

51. Second rubber sheet

60. Tire.

Claims (13)

1. An RFID tag for rubber products, characterized in that it has a communication transformer, an RF chip connected to the secondary side of the communication transformer, a circuit board on which the RF chip is installed, and an antenna, and the antenna has a coil portion, a first element extending from one end of the coil portion, and a second element shorter than the first element extending from the other end of the coil portion in parallel with the first element, and the number of turns of the coil part is less than the number of turns on the secondary side of the coupling transformer, and The coil part forms the primary side of the coupling transformer by holding the printed circuit board in the gap between the turns of the core of the coil part. 2. RFID tag for rubber products, described in paragraph 1, characterized in that it is intended for rubber products containing carbon black. 3. RFID tag for rubber products, described in paragraph 1 or 2, characterized in that the printed circuit board has insulating layers on the front and back surfaces. 4. RFID tag for rubber products, described in one of paragraphs. 1-3, characterized in that the coil part, the first element and the second element are formed by one wire. 5. RFID tag for rubber products, described in one of paragraphs. 1-4, characterized in that the axis of the inductor coil of the secondary side of the coupling transformer coincides with the axis of the coil part. 6. RFID tag for rubber products, described in one of paragraphs. 1-5, characterized in that if the length of radio waves at the radio frequency is λ, the electrical length of the unit consisting of the first element, the second element and the coil part is equal to λ/4. 7. A method for producing an RFID tag for rubber products, characterized in that it has a step in which several inductors of the secondary side of a communication transformer are placed in the left-right direction on the surface of the printed circuit board, a step in which slots are opened in front and behind several secondary side inductors arranged in the left-right direction, and a step in which cuts are made between several secondary side inductors placed in the left-right direction, there is also a step in which the coil part is made by the first side of the coupling transformer by inserting the inductor of the secondary side into the gap between the turns of the core of the coil part through the front slot using an antenna having a coil part, a first element extended from one end of the coil part, and a second element, shorter than the first element, extended from the other end of the spool portion in parallel with the first element.