Manufacturing method of near-field wireless communication antenna based on textile material

Abstract

The invention discloses a manufacturing method of a near-field wireless communication antenna based on a textile material, and the method comprises the steps: enabling an NFC antenna to be manufactured through laser induced LIG yarns, and enabling the LIG yarns to be embroidered into a fabric according to the designed geometrical shape and tension; the NFC antenna has the advantages that the NFC antenna can be integrated into clothes, wearable devices, household textiles and industrial textiles, and can be directly used for being connected with a network and a smart phone for wireless communication.

Description

Technical Field

[0001] The present invention relates to a near - field communication system, and more particularly to a manufacturing method of a near - field communication (NFC) wireless communication antenna based on textile materials, belonging to the field of NFC devices. Background Art

[0002] The research on traditional flexible electronic devices mainly focuses on printed electronic devices. Printed electronics technology transfers, sprays, or soft - etches circuits onto conductive or non - conductive flexible substrates. However, most of these devices use thin films as substrates and do not have the unique breathable and moisture - permeable characteristics of fabrics. In addition, due to the porous structure of textiles, it is not easy to combine such electronic devices with textiles.

[0003] Textile NFC technology mainly weaves conductive fibers directly into various functional electronic devices or connecting wires through knitting machines, weaving machines, or embroidery machines, retaining the bending, stretching, breathable, and moisture - permeable characteristics of the fibers themselves. However, different from the design methods of traditional electronic devices, the design must consider the characteristics of textile materials and the particularity of clothing wearing, that is: 1) The resolution of the woven geometric pattern is low, and the geometric shape of the device cannot adopt fine structures; 2) The resistivity of the woven wire is much higher than that of metals. In order to reduce the loss of the device, its geometric shape must be optimized; 3) The device will inevitably deform on clothing, so it is required that the electromagnetic characteristics of the device are not sensitive to shape changes; 4) In addition, the effects of parasitic capacitance and parasitic inductance of textile wires cannot be ignored. The inductance estimation method and equivalent circuit model used in traditional circuit design are no longer accurate for circuit design. These are all unique technical challenges of textile - based NFC.

[0004] However, during the manufacturing process, due to the large tensile force borne by the conductive fibers, the conductive coating on the fiber surface is damaged, thus affecting the electrical characteristics of the antenna. Currently, people's research on electronic device design based on textile processes only stays at the stage of single - device experiments and attempts, and there has been no research on this textile NFC. Summary of the Invention

[0005] In order to solve the above problems, the present invention designs a manufacturing method of a near - field wireless communication antenna based on textile materials, which can be integrated into clothing, wearable devices, household textiles, and industrial textiles, and can be directly used for wireless communication with a network and a smart phone.

[0006] The technical solution of the present invention is as follows: A manufacturing method of a near - field wireless communication antenna based on textile materials, including an NFC antenna embroidered on a fabric, and the specific steps are as follows: S1. Make LIG material into yarn; S2. Embroider the LIG yarn onto the fabric according to the coil pattern of the set NFC antenna; the LIG yarn can be integrated into the fabric in the stitch geometry and tension, and ensure good tensile elasticity, comfort performance and electrical performance, and realize the synchronous deformation of the coil and the fabric through the serpentine zig-zag stitch; S3. Induce the LIG coil by laser to convert the LIG yarn into graphene to form a conductor; S4. Connect the NFC antenna to the near-field communication circuit.

[0007] The fabric includes a dielectric fabric including a woven, non-woven or knitted fabric structure, as the substrate of the NFC antenna. The selected fabric has flexibility, stretchability, breathability, vapor permeability and washability, so as to meet the requirements of comfort, mechanical properties and wear resistance.

[0008] The LIG material is polyamide polyimide, polysulfone poly sulfone, polyethersulfone polyethersulfone, polyphenylsulfone poly phenyl sulfone, a carbon-based substance containing a cyclic carbon structure in the crystal. The carbon-based substance is a cellulose material, wood, paper, food, etc.

[0009] The laser wavelength is 9.3um - 10.6um, the laser energy is 50W - 75W, the laser duty cycle is 4 - 10%, the laser frequency is 6kHz, and the laser pulse number is 30 - 1000PPI. Among them, the laser energy is preferably 60W, and the laser pulse number is preferably 400PPI.

[0010] The spot diameter of the laser is 60 - 90um, preferably 70um in diameter.

[0011] The energy density of the laser is 5 - 200mj / cm 2 。

[0012] The laser emission device uses a pulse length of 8 - 12ps, a wavelength of 9 - 11um, and a repetition rate of 490kHz to 19.9MHz.

[0013] The NFC antenna has different shapes, including a rectangular ring, a circular ring or a polygonal ring.

[0014] The dielectric fabric directly realizes the antenna impedance matching, that is, the equivalent inductance, by using the antenna coil and chip embroidered with the conductive LIG yarn; when conjugate matching, the NFC antenna and the chip can work at 13.56MHz without any tuning circuit.

[0015] The NFC antenna has good air permeability and moisture permeability.

[0016] The NFC antenna has good capabilities of resisting tensile deformation, bending deformation, and twisting deformation.

[0017] The NFC antenna is disposed on the dielectric fabric of the substrate, and the antenna coil embroidered with LIG yarn is directly connected to the chip.

[0018] The fabric is made of natural fibers or man-made fibers.

[0019] The product of the near-field communication wireless communication system based on textile materials of the present invention can be applied to textiles, clothing or accessories, and these clothes can be worn unobtrusively and can be in wireless contact with clouds, networks and electronic platforms such as smart phones, tablets, smart watches, etc. It can be widely applied in household control, vehicle seat cushions, navigation, personal identification, entertainment, etc. and embroidery can be performed on various fabrics in the textile system.

[0020] The NFC antenna can be flexibly embroidered in textiles such as clothing, accessories, household or automotive textiles, and data can be transmitted to the electronic platform through wireless communication connection.

[0021] The dielectric fabric can be designed according to a calculation model, and the antenna coil embroidered with conductive yarn and the chip are directly matched to ensure the maximum radiation efficiency without adding other electronic devices, reducing the energy loss.

[0022] The NFC antenna can be applied to electronic platforms, including smart phones, reader devices, smart watches, smart wristbands, computers, and POS machines.

[0023] The NFC antenna is of an NFC antenna loop structure and is embroidered on the fabric by a conductive yarn having a normal sewing thread with high breaking strength or a specific yarn determined by the surface and breaking characteristics meeting the requirements, transversely with respect to a fancy untwisted yarn.

[0024] The LIG yarn can be embroidered by ordinary needling, for example: single-thread chain stitch such as 101 single-thread chain stitch, multi-thread chain stitch such as 401 double chain stitch, and lock stitch such as 301 zigzag. High-friction, easily broken, and untwisted yarns cannot withstand high tension. Their filaments are easily broken under high stress and external force speed, so they must be fixed on the fabric with the help of other common sewing yarns to keep them stable. The serpentine zig-zag stitch design, that is, the conductive wire is fixed by an elastic bobbin thread and a face thread, and synchronous deformation with the fabric is achieved during stretching.

[0025] The fabric can be made of natural fibers such as cotton fabric, silk fabric, linen fabric, wool fabric, and leather fabric or man-made fibers such as acetate fabric, chiffon fabric, acrylic fabric, organdy fabric, and nylon fabric. The fabric, i.e., the material, can be polyester fabric, etc.

[0026] By adjusting the speed of the embroidery machine and regulating the tension and shape of the stitch, its high electrical and mechanical properties are ensured.

[0027] The distance between the NFC antenna and the electronic platform, i.e., the electronic device, is about 0 - 20 cm.

[0028] The beneficial effects of the present invention are as follows: A wearable NFC antenna can be manufactured from textiles by embroidery, and data can be obtained and transmitted through physical contact with the textiles.

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Description of the Drawings

[0030] FIG. 1 is a diagram of NFC tags with different shapes according to an embodiment of the present invention ( Figure 1a - rectangular, Figure 1b - circular, Figure 1c - polygonal); FIG. 2 is a structural diagram of an NFC tag embroidered on a fabric, textile or clothing according to an embodiment of the present invention; FIG. 3 is a stitch geometry diagram of NFC according to an embodiment of the present invention ( Figure 3a - W-head embroidery sewing thread, Figure 3b zigzag sewing thread, FIG. 3c301-level flat sewing thread, in the figure: zig-zag - serpentine sewing thread, Class 107 chainstitch - 107-level chain stitch, Needlethread - needle thread, bobbin thread - bobbin thread, Class301 lockstitch - 301-level flat sewing thread); FIG. 4 is an equivalent circuit diagram of an NFC tag according to an embodiment of the present invention (in the figure: Ls-ant, Cs-ant and Rs-ant respectively represent its inductance, parasitic capacitance and resistance); FIG. 5 is an NFC matching circuit diagram according to an embodiment of the present invention (in the figure: Rs, Cs and Cp respectively represent the series / parallel resistance, series / parallel capacitance and parallel capacitance of the matching circuit); Figure 6 FIG. is an NFC antenna diagram matched with an NFC chip according to an embodiment of the present invention (in the figure: diode chip - NFC chip, Matching circuit - matching circuit, NFC antanna - NFC antenna).

[0031] Figure 7 FIG. is the working process of manufacturing a conductive NFC antenna by laser-induced LIG yarn in the present invention. Detailed Embodiments

[0032] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention. Embodiment

[0033] A near-field communication wireless communication system based on textile materials includes an NFC antenna. The NFC antenna can have different shapes. As shown in Figure 1, the NFC antennas with different shapes, for example Figure 1a rectangle, Figure 1b circle and Figure 1c polygonal devices. The shape of the NFC coil depends on the position, size, and intensity in a specific wearing or display area. For example, the polygon has high stretchability and can perform well under high deformation conditions.

[0034] Use an electronic embroidery machine to embroider the NFC antenna with LIG yarn conductive yarn on the fabric to form coil 1, chip, and matching circuit 2.

[0035] As shown in Figure 2, the NFC antenna is embroidered or sewn with LIG yarn onto the fabric, textile, or clothing by an automatic machine. Since the LIG yarn itself is not conductive, the embroidered or sewn NFC antenna cannot work properly. After the embroidery or sewing of the NFC antenna is completed, laser induction is carried out along the position of the LIG yarn using a laser, so that the LIG yarn is transformed into graphene to form a conductor, as shown in Figure 7 shown.

[0036] When using a laser to perform laser induction on the LIG yarn, a corresponding laser needs to be used, including laser frequency, energy density, etc. The inventors of the present invention have obtained appropriate laser induction parameters through research. Specifically, the laser frequency is 3372.8 kHz, and the energy density is 15.8 - 25.2 mj / cm 2 ², and the emission device uses a pulse length of 10 ps, a wavelength of 355 nm, and a pulse repetition rate of 490 kHz to 19.9 MHz.

[0037] The NFC antenna includes coil 1, a chip, and matching circuit 2 made of the yarn formed by the above-mentioned laser induction. The chip and the matching circuit are welded through additional conductive yarn 3. The fabric 4 used as the substrate of the NFC antenna, that is, the substrate, is made of natural fibers (such as woven cotton fabric, silk fabric, linen fabric, wool fabric, and leather fabric), artificial fibers (such as acetate fabric, chiffon fabric, acrylic fabric, organza fabric, lastex fabric, nylon fabric, polyester fabric, etc.), non-woven or knitted structures.

[0038] The LIG yarn is based on the requirements of the NFC coil for conductivity and inductance. The thin and smooth LIG yarn can be embroidered with an ordinary embroidery machine. Examples of the stitch geometries of the zigzag and class 301 flat seams are shown in Figure 3, 3b and 3c. Yarns with high friction and easy to break (such as stainless steel yarns) can be placed on the textile and smoothly moved by placing them near the needle tip. The geometries are shown in Figure 3, 3a - W - head embroidery stitch. 3b - Zigzag stitch. 3c - Class 301 flat seam.

[0039] The NFC antenna is essentially a conductive coil with a specific number of turns. Therefore, its equivalent circuit can be represented by an inductor, a parasitic capacitor, and a resistor. The following Figure 4 illustrates the equivalent circuits of NFC tags connected in series and in parallel. Ls / p - ant, Cs / p - ant, and Rs / p - ant represent their inductance, parasitic capacitance, and resistance respectively. It should be noted that the magnitude of the parasitic capacitance Cs - ant is only 10 pF. Therefore, the electrical characteristics of the NFC tag are affected by its inductance and resistance.

[0040] To maximize the antenna efficiency, a matching circuit is usually employed to ensure the conjugate matching of the equivalent impedance of the NFC tag plus the matching circuit with the NFC reader. Figure 5 shows a typical series matching circuit and a parallel matching circuit for NFC tags. Rs / p, Cs / p, and Cp represent the series / parallel resistance, series / parallel capacitance, and parallel capacitance of the matching circuit respectively.

[0041] The parasitic capacitance is formed along the length of the yarn and its effect on the NFC antenna can be modeled as a capacitor that is connected in parallel with an inductor and a resistor in series, as shown in Figure 5. Usually, a matching circuit is inserted between the NFC chip and the coil antenna to adjust its operating frequency to 13.56 MHz. If the impedance of the antenna and the NFC chip is conjugate - matched, no matching circuit is required and maximum energy transfer between the chip and the antenna can be achieved.

[0042] For Figure 6 the NFC coil antenna in (1) ρ_1 is the modified inductance coefficient of the embroidery coil. Representing its parasitic capacitance and intrinsic resistance respectively. The impedance of the antenna is denoted as (2).

[0043] (2) Where ω is the angular frequency, with a value of around 10 MHz. In NFC applications, the orders of magnitude of R_(s-ant), L_(s-ant), and C_(s-ant) are 1 Ω, 1 µH, and 1 pF, respectively. Using the magnitude of the variables in the formula |jωR_(s-ant)C_(s-ant)| ≪ 1, the reactant part of (2) can be simplified to (3).

[0044] (3) To achieve conjugate matching between the chip and the antenna, we can simplify the reactive part of the impedance Z_ant to an inductor, i.e., the equivalent inductor L_(s-eqv), which already incorporates the parasitic capacitance. The capacitance value. L_(s-eqv) can be expressed as (4), and the conjugate matching connection with the chip is shown in Figure 5.

[0045] (4) The parasitic capacitance C_(s-ant) is related to the formation of the gap along the stitch. Quantitatively, C_(s-ant) is proportional to the total length of the air gap along the line l_g and the thickness of the line, and inversely proportional to the minute gap g. The parasitic capacitance can be expressed as (5).

[0046] (5) ε_yarn can be regarded as the absolute dielectric constant of air and the textile matrix. g and t are values affected by the yarn properties. However, due to the minute gap distribution in the twisted fibers, the exact values of g and t cannot be quantified.

[0047] The length of the air gap along the stitch lg is a geometric factor, closely related to the length of the conductor, and can be calculated based on the geometry of the coil, as shown in (6) and (7) for circular and square coils, respectively. Where n is the number of turns of the coil. a = 0.5(r_i + r_o), b = r_o - r_i, and r_o and r_i are the outer and inner radii of the coil, respectively. r_i = r_o - n(s + w) - w.

[0048] (6) (7) The reciprocal of L_(s-eqv) can be expressed by (8).

[0049] (8) Substituting (6) or (7) into (5), and then substituting (5) and (1) into (8), the equivalent coil inductance can be expressed by (9).

[0050] (9) Since the variables ε_yarn, g, and t are all structure-related variables, it is difficult to quantify them with definite values. For simplicity, these variables are combined into a coefficient ρ_2.

[0051] (10) (11) The operating resonant frequency is determined by (12), and its accuracy will be affected if the parasitic capacitance C_(s-ant) of the coil is ignored. The impedance of the NFC chip and the conjugate-matched antenna impedance, i.e., the equivalent inductance, are listed in Table 3.

[0052] (12) When the NFC coil formed by the LIG yarn reaches conjugate matching, the NFC antenna and the chip can operate at the required 13.56 MHz without any tuning circuit.

[0053] The product of the present invention is an application of textile-based NFC. It can be embroidered on textile systems, including clothes, accessories (such as hats and bags), and household textiles, car seat cushions, etc. The embroidered antenna will reduce the price of NFC in the manufacturing process, thus promoting the application system of NFC in the Internet of Things. By integrating NFC directly as a necessity rather than an accessory into textiles, it can be used for purposes such as monitoring, healthcare, home control, entertainment, etc., which have a huge impact on daily life.

Claims

1. A method for manufacturing a near-field wireless communication antenna based on textile materials, characterized in that: The LIG yarn is embroidered into the fabric according to the designed geometry and tension, and the NFC antenna structure is woven and attached to the fabric. The specific steps are as follows: S1. Making LIG material into yarn; S2. Embroidering LIG yarn onto fabric according to the pattern of the designed NFC antenna; S3. Laser-induced conversion of LIG yarn into graphene for NFC antenna, thus making it conductive; S4. Connect the NFC antenna to the near field communication circuit.

2. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The substrate material includes a dielectric fabric including a woven, nonwoven or knitted structured fabric, which serves as a substrate for the NFC antenna.

3. A method for manufacturing a near-field wireless communication antenna based on textile materials, characterized in that: The LIG material is polyimide, polysulfone, polyethersulfone, polyphenylsulfone, or a carbon-based substance containing a ring-shaped carbon structure in the crystal.

4. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The laser wavelength is 9.3um -10.6um, the laser energy is 50W-75W, the laser duty cycle is 4-10%, the laser frequency is 6kHz, and the laser pulse number is 30-1000PPI.

5. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The spot diameter of the laser is 60-90 um.

6. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The energy density of the laser is 5-200mj / cm 2 .

7. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The laser emission device adopts a pulse length of 8-12ps, a wavelength of 9-11um, and a repetition rate of 490kHz to 19.9MHz.

8. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The NFC antenna has different shapes, including a rectangular ring, a circular ring, or a polygonal ring.

9. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 2, characterized in that: The NFC antenna is set on the dielectric fabric of the substrate, and the antenna coil embroidered with LIG yarn is directly connected to the chip.

10. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 9, characterized in that: The dielectric fabric uses an antenna coil and a chip embroidered with conductive LIG yarn to directly achieve antenna impedance matching, that is, equivalent inductance; when conjugate matched, the NFC antenna and chip can operate at 13.56 MHz without any tuning circuit.

11. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The NFC antenna has good air permeability and moisture permeability.

12. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The NFC antenna has good resistance to tensile deformation, bending deformation and twisting deformation.

13. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The NFC antenna can be applied to electronic platforms, including smart phones, reader devices, smart watches, smart wristbands, computers, and POS machines.

14. The method for manufacturing a textile material-based near-field wireless communication antenna according to claim 1, characterized in that: The fabric is made of natural fibers or artificial fibers.

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