A metal smart card

Abstract

The application discloses a metal smart card, comprising: a metal body, a hollow gap pattern formed by cutting on the metal body defines a metal antenna area at a set position in the metal body, the metal antenna area is composed of continuous conductive material, and a first electrical connection point and a second electrical connection point are defined in the metal antenna area; the hollow gap pattern is configured to include at least one gap segment in communication with the outer edge of the metal body for intermittently surrounding a closed conductive path composed of the metal body of the metal antenna area; a chip module is electrically connected with the first electrical connection point and the second electrical connection point respectively, so that the metal antenna area constitutes at least part of the conductive path of the radio frequency antenna of the chip module. The metal body of the application simultaneously assumes the functions of structural support and radio frequency antenna, reduces the space occupied by the independent antenna, and improves the utilization rate of metal materials; the closed conductive path surrounding the metal antenna area is intermittent, reduces the electromagnetic loss generated by the closed metal loop, and improves the stability of radio frequency communication.

Description

Technical Field

[0001] This invention relates to the field of radio frequency communication smart card technology, and specifically to a metal smart card. Background Technology

[0002] Smart cards typically consist of a card body, a chip module, and an antenna module. The chip module receives radio frequency energy generated by an external card reader through the antenna module and interacts with the card reader for data exchange. Currently, the antenna module of contactless smart cards is usually formed using methods such as wound coils, etched coils, or printed antennas. This type of antenna requires a non-metallic area to be reserved inside the card body to avoid the effects of metallic materials on radio frequency fields, such as shielding, eddy current loss, and impedance changes.

[0003] However, with changing market demands, the need for metal smart cards is growing. The metal body of smart cards, due to its high strength, good wear resistance, and metallic texture, is used in high-end payment cards, identity cards, and membership cards. However, the metal body has excellent electrical conductivity. When a traditional coil antenna is placed near the metal body, the metal body easily alters the electromagnetic distribution around the antenna, reducing the antenna's quality factor and leading to shorter communication distances or decreased communication stability. Furthermore, currently available metal smart cards all have separate antenna units, not connected to the metal; and the technology is designed to reduce interference from the metal on radio frequency signals, resulting in shorter reading distances compared to non-metal smart cards. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a metal smart card that solves the problems of communication instability and low reliability caused by the shielding interference of the metal body on radio frequency signals in traditional technology.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: This invention provides a metal smart card, comprising: A metal body having a hollowed-out slit pattern formed by cutting, the hollowed-out slit pattern defining a metal antenna region at a predetermined position in the metal body, the metal antenna region being made of a continuous conductive material, and defining a first electrical connection point and a second electrical connection point within the metal antenna region. The perforated slit pattern is configured to include at least one slit segment that communicates with the outer edge of the metal body, for discontinuously surrounding the closed conductive path formed by the metal body surrounding the metal antenna region; A chip module, wherein the chip module is electrically connected to the first electrical connection point and the second electrical connection point respectively, such that the metal antenna region constitutes at least a portion of the conductive path of the radio frequency antenna of the chip module.

[0006] In some embodiments, the continuous conductive material is the first conductive material retained after the metal body is cut.

[0007] In some embodiments, the continuous conductive material is a second conductive material that is heterogeneous to the metal body, and a hollowed-out slit pattern is formed by cutting on the second conductive material.

[0008] In some embodiments, the perforated slit pattern extends along a continuous curved path, at least a portion of which includes at least one of a spiral path that gradually unfolds around a central region and a serpentine path that extends back and forth along the length or width of the metal body.

[0009] In some embodiments, the metal antenna region includes a first group of adjacent metal segments separated by a first spacing gap and a second group of adjacent metal segments separated by a second spacing gap; At the target communication frequency, the potential difference between the first group of adjacent metal segments is greater than the potential difference between the second group of adjacent metal segments; The width of the first gap is greater than the width of the second gap.

[0010] In some embodiments, a tuning capacitor is further connected between the first electrical connection point and the second electrical connection point; The tuning capacitor is connected in parallel with the chip module.

[0011] In some embodiments, a protection capacitor is also included, which is connected in series with the chip module.

[0012] In some embodiments, the resonant frequency of the radio frequency circuit formed by the metal antenna region and the tuning capacitor is located within the target communication frequency band of the chip module.

[0013] In some embodiments, under a preset wireless transducer frequency band and a preset external field strength, the input power transmitted to the chip module via the protection capacitor is not higher than the allowable input power of the chip module.

[0014] In some embodiments, the perforated slit pattern includes a first perforated area and a second perforated area; The first hollow area is filled with a first insulating material; The second hollow area is provided with a buffer layer located on one side of the hollow wall and a support layer located on the side wall of the buffer layer; The dielectric constant of the first insulating material is less than that of the supporting layer, and the elastic modulus of the buffer layer is less than that of the supporting layer.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: By cutting and hollowing out the area defined by the metal smart card, a hollowed-out pattern with a certain design is formed. The continuous conductive material formed after cutting is used to form the metal antenna area, so that the metal body can simultaneously bear the structural support and radio frequency antenna functions, reduce the space occupied by independent antennas, and improve the utilization rate of metal materials. Furthermore, by setting a gap segment that connects to the outer edge of the metal body, the closed conductive path surrounding the metal antenna area is interrupted, reducing the electromagnetic loss generated by the closed metal loop and improving the stability of radio frequency communication.

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0017] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of a metal smart card provided in one embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the overall structure of a metal smart card provided in another embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram showing the connection relationship between the metal antenna region, the first electrical connection point, the second electrical connection point, the tuning capacitor, the protection capacitor, and the chip module.

[0021] Figure 4 This is a schematic diagram of the overall structure of the metal antenna region formed by the heterogeneous second conductive material provided in one embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the filling structure of the first and second hollow areas provided in one embodiment of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may not be directly connected to the other devices but may have an intermediary device.

[0026] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0027] Reference Figures 1 to 4 This application proposes a metal smart card, comprising: The metal body 10 has a hollowed-out slit pattern 20 formed by a cutting process. The hollowed-out slit pattern 20 defines a metal antenna region 30 at a predetermined position in the metal body 10. The metal antenna region 30 is made of a continuous conductive material and defines a first electrical connection point 31 and a second electrical connection point 32 within the metal antenna region 30. The hollowed-out slit pattern 20 is formed by a cutting process and occupies an area A on the metal body 10. However, the metal antenna region 30 defined by it occupies an area B on the metal body 10. In some possible embodiments, B is greater than A. That is, a smaller hollowed-out slit pattern 20 defines a larger metal antenna region 30. The metal antenna region 30 includes the hollowed-out slit pattern 20 and a metal body 10 with a certain area, and defines the first electrical connection point 31 and the second electrical connection point 32 in this area. Among them, "metal body 10, having a hollowed-out slit pattern 20 formed by a cutting process" includes at least the following two cases: Reference Figure 1 Optionally, a hollowed-out slit pattern 20 can be formed by directly cutting into the material of the metal body 10, and this hollowed-out slit pattern 20 is directly embedded in the material of the metal body 10; wherein, Figure 1The lower half of the middle dotted line is the set position of the hollowed-out slit pattern 20 in the metal body 10, which defines the metal antenna area 30. Reference Figure 4 Optionally, the hollowed-out slit pattern 20 is formed by a cutting process in the area defined by the metal body 10, that is, the card area. Therefore, the hollowed-out slit pattern 20 may not fall directly in the material of the metal body 10, but falls in the card area. Preferably, the metal body 10 can be replaced with a second conductive material 50 in the set area by material replacement, and then the second conductive material 50 is cut. Therefore, the hollowed-out slit pattern 20 falls in the replaced second conductive material 50. The cutout pattern 20 is configured to include at least one cutout segment 21 that communicates with the outer edge of the metal body 10, for discontinuing the closed conductive path formed by the metal body 10 surrounding the metal antenna region 30; that is, in addition to including the continuous curved path that specifically constitutes the antenna part, the cutout pattern 20 also includes at least one cutout segment 21, which communicates with both the continuous curved path of the antenna part and the outer edge of the metal body 10. Chip module 40 is electrically connected to a first electrical connection point 31 and a second electrical connection point 32, such that the metal antenna region 30 constitutes at least a portion of the conductive path of the radio frequency antenna of chip module 40; Figure 1 and Figure 2 As shown, for ease of illustration, the chip module 40 is drawn on the outside of the metal body 10. This is only for the sake of understanding. In fact, the chip module 40 is arranged inside the metal body 10.

[0028] It should be noted that, in response to the problems of traditional metal smart cards requiring a separate antenna module within the metal card body, the metal body 10 easily generating undesirable closed currents, and the antenna occupying additional installation space, this embodiment defines a metal antenna region 30 by forming a hollowed-out slit pattern 20 at a designated position on the metal body 10. This metal antenna region 30 is not composed of a separate antenna module, but rather forms an antenna by using conductive material to maintain a continuous conductive state. The metal antenna region 30 defines a first electrical connection point 31 and a second electrical connection point 32 within the metal body 10, and uses the first electrical connection point 31 and the second electrical connection point 32 to electrically connect with the chip module 40. This allows the radio frequency current induced in the metal antenna region 30 by the external alternating magnetic field to be transmitted to the chip module 40 through the two electrical connection points. The load modulation signal generated by the chip module 40 can also be coupled outward through the metal antenna region 30. Therefore, the metal antenna region 30 no longer serves merely as a card shell or support structure, but constitutes all or part of the radio frequency antenna conductor.

[0029] Reference Figure 1 and Figure 2Furthermore, to reduce the impact of the current loop formed by the outer metal body 10 on the radio frequency field distribution, this embodiment further specifies that the hollowed-out slit pattern 20 is provided with at least one slit segment 21. This slit segment 21 extends to the outer edge of the metal body 10, interrupting the closed conductive path formed by the metal body 10 surrounding the metal antenna region 30, thus preventing the formation of an undesired circulating current that flows completely around the metal antenna region 30 within the metal body 10. Simultaneously, the slit segment 21 connecting the edge of the metal body 10 does not cut off the continuous conductive path required between the first electrical connection point 31 and the second electrical connection point 32. In other words, the gap formed at the end of this slit does not affect the continuous conductive path formed by the metal body 10 at the first electrical connection point 31 and the second electrical connection point 32. By setting the functional antenna current path and the outer closed conductive path respectively, the metal body 10 can participate in radio frequency communication and effectively reduce the impact of the outer metal loop on the radio frequency field distribution.

[0030] Furthermore, regarding the hollowed-out slit pattern 20 formed on the metal body 10 through a cutting process, there are at least two implementation methods. One method involves directly cutting the metal body 10 of the smart card, cutting the metal body 10 itself, and using the first conductive material 11, which is of the same material as the metal body 10, to form the metal antenna region 30. The other method involves first replacing the first conductive material 11 with a second conductive material 50 at a set position on the metal body 10 of the smart card, and then cutting on the second conductive material 50 to form the metal antenna region 30. The two methods are described in detail below: Combination Figure 1 and Figure 2 In one implementation, the continuous conductive material is the first conductive material 11 retained after the metal body 10 is cut. By partially cutting the metal body 10, a metal antenna region 30 is formed at a set position. This metal antenna region 30 has a set length and shape, thereby forming a conductive path. This conductive path is used as all or part of the radio frequency antenna conductor of the chip module 40.

[0031] This structural design is suitable for scenarios where the electrical conductivity, mechanical strength, and processing performance of the metal body 10 itself meet the product requirements. The cutting equipment removes only a small amount of metal material needed to form the hollowed-out slit pattern 20; the remaining metal material remains part of the original metal body 10. Since there is no need to separately manufacture and assemble a complete independent antenna, the antenna carrier, adhesive layer, and positioning structure can be reduced, while increasing the proportion of metal material retained in the card surface.

[0032] Preferably, the first conductive material 11 is made of 304 stainless steel, tungsten steel, titanium alloy, copper alloy or other conductive metal.

[0033] Combination Figure 4 In another implementation, the continuous conductive material is a second conductive material 50 that is heterogeneous to the metal body 10. A predetermined location on the metal body 10 is hollowed out and replaced with the second conductive material 50. A perforated slit pattern 20 is cut into the second conductive material 50, allowing it to form an independent metal antenna region 30. The conductive path formed by the continuously conductive second conductive material 50 serves as all or part of the radio frequency antenna conductor of the chip module 40. Figure 4 As shown, the area within the dashed box is the second conductive material 50 that has been replaced, and the area within the dashed box is the defined metal antenna region 30, which includes the hollowed-out slit pattern 20, the first electrical connection point 31, and the second electrical connection point 32. Because some metallic materials, while possessing good appearance or structural strength, may have electrical conductivity, magnetic properties, or precision cutting performance unsuitable for directly forming target radio frequency antennas, a second conductive material 50, dissimilar to the metal body 10, can be replaced at a predetermined location on the metal body 10, and a perforated slit pattern 20 can be cut into the second conductive material 50.

[0034] Preferably, an insulating layer is provided between the second conductive material 50 and the metal body 10 to prevent the metal body 10 from bridging the gaps on the second conductive material 50; the gap structure on the second conductive material 50 is connected to the edge insulating opening on the metal body 10, so that the metal closed path surrounding the metal antenna region 30 is interrupted; at this time, the first electrical connection point 31 and the second electrical connection point 32 both fall on the second conductive material 50. That is, after the metal body 10 and the second conductive material 50 are isolated by the insulating layer, the antenna part and the electrical connection point part both fall on the second conductive material 50. This part is connected to the chip module 40 through the two electrical connection points and performs the function of radio frequency current transmission.

[0035] With the second conductive material 50, the card body of the metal smart card consists of two parts: a metal body 10, which mainly provides support, protection, and aesthetics; and the second conductive material 50, which mainly transmits radio frequency current. The two materials can be selected based on their mechanical and radio frequency performance, respectively, without requiring the same material to meet all design requirements simultaneously. In this embodiment, the metal body 10 and the second conductive material 50 are used in combination. In this case, the "hollowed-out slot pattern 20 on the metal body 10" includes an antenna slot formed on the second conductive material 50 and an edge insulating opening formed on the metal body 10 that communicates with the antenna slot. Together, they constitute a slot structure with an intermittently closed conductive path.

[0036] Preferably, the second conductive material 50 is made of copper, copper-nickel alloy, silver alloy, copper-plated metal sheet or other conductive materials.

[0037] In another implementation, the first conductive material 11 and the second conductive material 50 are combined. Specifically, based on the use of a heterogeneous second conductive material 50 to form the metal antenna region 30, the metal antenna region 30 formed by the second conductive material 50 can be combined with the conductive path formed by the first conductive material 11, which also functions as a metal antenna, to form a complete antenna. For example, the metal body 10 is partially cut to form a first conductive path, and the second conductive material 50 is cut to form a second conductive path. The two are connected by a conductive bridge to form a continuous radio frequency circuit. The first conductive material 11 and the second conductive material 50 together constitute the radio frequency antenna conductor, wherein the metal antenna region 30 formed by the first conductive material 11 and the metal antenna region 30 formed by the second conductive material 50 each constitute a part of the radio frequency antenna conductor. In this case, the second conductive material 50 mainly undertakes the function of radio frequency current transmission, while the first conductive material 11 mainly undertakes the functions of mechanical support and appearance maintenance.

[0038] Furthermore, the metal antenna region 30 constitutes at least a portion of the conductive path of the RF antenna of the chip module 40. That is, the metal antenna region 30 can constitute either the entirety or a part of the RF antenna conductor of the chip module 40. The specific composition of the RF antenna conductor can be selected based on product size, RF performance requirements, assembly method, and cost requirements. Specifically: In one possible implementation, the metal antenna region 30 constitutes the entire RF antenna conductor of the chip module 40. In this case, the continuous conductive material remaining after the metal body 10 is cut through the perforated pattern 20 forms a complete RF current transmission path. The first electrical connection point 31 and the second electrical connection point 32 are respectively connected to the two antenna ends of the chip module 40. The chip module 40 and the metal antenna region 30 together form a complete RF communication loop. The RF current enters the metal antenna region 30 from the first electrical connection point 31, is transmitted through the continuous conductive material to the second electrical connection point 32, and then returns to the chip module 40, thereby completing RF energy coupling and data communication. Except for the solder joints, conductive adhesive, or connecting wires necessary for connecting the chip module 40, the RF antenna conductor does not contain any other conductive structures; therefore, the metal antenna region 30 constitutes the entire RF antenna conductor.

[0039] For example, in a smart card using 304 stainless steel or titanium alloy as the metal body 10, a continuous spiral path 22 or a serpentine path 23 is formed by laser cutting, and the metal strips retained after cutting are directly used as radio frequency antennas. The first electrical connection point 31 and the second electrical connection point 32 are located at the two ends of the continuous conductive path and are directly connected to the chip module 40. The entire radio frequency antenna consists only of the metal antenna area 30, and flexible circuit board antennas, printed circuit antennas, or wire-wound antennas are no longer provided.

[0040] In this configuration, the metal antenna region 30 not only performs the function of transmitting radio frequency current but also undertakes the functions of antenna inductance formation and magnetic field coupling. By adjusting the length, width, number of turns, spacing between adjacent metal segments, and thickness of the metal material of the perforated slot pattern 20, the equivalent inductance, resistance, and parasitic capacitance of the metal antenna region 30 can be changed, enabling it to form a radio frequency loop with the chip module 40 that meets the requirements of the target communication frequency band. This structure is suitable for applications where the metal body 10 material has good conductivity and can be processed to form stable radio frequency parameters.

[0041] However, in another embodiment, the metal antenna region 30 forms part of the RF antenna conductor of the chip module 40. In this case, the complete RF antenna conductor is composed of the metal antenna region 30 and other conductive structures, which are electrically connected to each other to form a continuous RF current path. Preferably, the other conductive structures include copper foil conductors on flexible printed circuit boards, copper foil conductors on rigid printed circuit boards, metal wires, conductive connecting pieces, or other conductive components capable of transmitting RF current.

[0042] For example, one end of the metal antenna region 30 is connected to a copper foil conductor on a flexible printed circuit board (FPC) via a first electrical connection point 31, and the other end of the FPC is connected to a chip module 40; the other end of the metal antenna region 30 is directly connected to the chip module 40 via a second electrical connection point 32, or connected to a copper foil conductor on a printed circuit board (PCB). Radio frequency current flows sequentially through the metal antenna region 30, the flexible printed circuit board conductor, and the chip module 40. All conductive parts together constitute a complete radio frequency antenna conductor, with the metal antenna region 30 undertaking a portion of the conductive path of the radio frequency antenna conductor and participating in the formation of antenna inductance and radiated magnetic field.

[0043] In another implementation, one end of the metal antenna region 30 is connected to a wire, and the other end of the wire is connected to an antenna conductor on a printed circuit board. The antenna conductor on the printed circuit board is then connected to the chip module 40. Alternatively, the metal antenna region 30 is connected to two independent conductive structures via wires, and multiple conductive structures are connected in series to form a complete radio frequency antenna conductor. The aforementioned conductive structures can be copper foil on a flexible printed circuit board, copper foil on a rigid printed circuit board, metal connecting bridges, conductive sheets, metal springs, or other radio frequency transmission structures with conductivity. In this structural approach, the metal antenna region 30 utilizes the large conductive area of ​​the metal body 10 to provide partial inductive and magnetic field coupling capabilities, while the copper foil conductor on the circuit board is used to adjust the connection position, compensate impedance, and optimize the layout of the chip module 40.

[0044] In another embodiment, to improve RF matching performance or optimize the internal space layout of the card, a tuning circuit, impedance matching network, or protection circuit can be arranged between the metal antenna region 30 and the chip module 40. In this case, although circuit elements are added to the RF loop, the metal antenna region 30 or the metal antenna region 30 plus other conductive structures connected to it still performs the RF conduction function, with each conductive structure forming a continuous RF antenna conductor. Those skilled in the art should understand that the circuit elements themselves do not act as antenna conductors, but only participate in impedance matching, resonance adjustment, or energy protection; therefore, this does not affect the technical meaning that the metal antenna region 30 constitutes all or part of the RF antenna conductor.

[0045] The term "constituting part of the radio frequency antenna conductor" as used in this invention refers to the metal antenna region 30 participating in radio frequency current transmission and forming a complete radio frequency current path together with other conductive structures. The term "constituting the entire radio frequency antenna conductor" refers to the fact that the transmission path of radio frequency current between the two antenna ends of the chip module 40 is entirely provided by the metal antenna region 30, excluding other antenna conductors except for the connection structure. Both of the above embodiments fall within the protection scope of this invention.

[0046] It should be noted that when the metal antenna region 30 forms part of the RF antenna conductor, it does not mean that the metal antenna region 30 exists only as a regular connecting wire. The metal antenna region 30 still participates in the electromagnetic conversion process of the RF antenna. The RF current flowing inside it generates a corresponding magnetic field, affecting the equivalent inductance, quality factor, and impedance characteristics of the entire RF antenna. Other conductive structures are mainly used to cooperate with the metal antenna region 30 to form a complete current path, adjust antenna parameters, or adapt the installation position of the chip module 40.

[0047] This embodiment specifically limits these two scenarios because metal smart cards have different design schemes under different product forms: when the processing precision and material performance of the metal body 10 meet the requirements, the metal antenna area 30 can completely replace the traditional coil antenna, allowing the metal body 10 to directly undertake the antenna function; when the card structure, material selection, or chip layout needs further optimization, the metal antenna area 30 can be combined with flexible circuit boards, printed circuit boards, wires, or other conductive structures, allowing the metal antenna area 30 to participate in the formation of the radio frequency antenna conductor, and then combined with other conductive structures to meet specific form requirements. Regardless of the method, the metal structure is used to participate in the radio frequency current transmission, the metal antenna area 30 participates in the formation of the radio frequency current path, and the conductive area in the metal body 10 is transformed from a traditional mechanical support structure into a radio frequency antenna functional structure.

[0048] Combination Figure 1 and Figure 2 In some possible embodiments, the cutout pattern 20 extends along a continuous curved path, at least a portion of which includes at least one of a spiral path 22 that gradually unfolds around the central region and a serpentine path 23 that extends back and forth along the length or width of the metal body 10. In the spiral path 22, the metal antenna region 30 extends outward gradually around the central point; this central point is also determined by prior design, and the hollowed-out part of the continuous conductive material spirals outward multiple times around this central point. In the serpentine path 23, the metal antenna region 30 is arranged back and forth along the length or width of the card; after selecting a starting point, the hollowed-out part of the continuous conductive material extends in a serpentine manner towards the long or short side. The two types of paths can be used individually or connected within the same metal antenna region 30; optionally, a spiral path 22 can be followed by a serpentine path 23.

[0049] Regardless of the path method, the goal is to solve the problem of insufficient antenna current path length due to limited card body planar area. By designing the continuous curved path as a multi-turn spiral or a serpentine extension with multiple turns, the effective conductive length between the first electrical connection point 31 and the second electrical connection point 32 is increased. The equivalent inductance and parasitic capacitance can be adjusted by the number of turns, the number of turns, the turning radius, and the spacing between adjacent segments.

[0050] In some possible embodiments, the metal antenna region 30 includes a first group of adjacent metal segments separated by a first spacing slot and a second group of adjacent metal segments separated by a second spacing slot; At the target communication frequency, the potential difference between the first group of adjacent metal segments is greater than the potential difference between the second group of adjacent metal segments. The width of the first gap is greater than the width of the second gap.

[0051] It should be noted that if the gap width between adjacent metal segments is designed to be uniform, it may lead to problems such as parasitic capacitance, metal retention rate and processing reliability. This is because different positions of the metal antenna region 30 have different radio frequency potentials. If the potential difference between adjacent metal segments is larger, the electric field between them is usually stronger, and the parasitic capacitance generated by the gap will have a more significant impact on the antenna parameters.

[0052] Therefore, two different adjacent metal segments are designed with different gap widths. The first group of adjacent metal segments has a larger potential difference at the target communication frequency, and its corresponding first gap width is set to be larger. The second group of adjacent metal segments has a smaller potential difference, and its corresponding second gap width is set to be smaller. The potential difference between adjacent metal segments can be obtained through full-wave electromagnetic simulation, or through near-field testing, voltage probe measurement, or calculation from an equivalent circuit model.

[0053] It should be noted that when dividing the first and second groups, optionally, a potential difference threshold can be set between adjacent metals in the first group and adjacent metals in the second group, or the division can be based on the potential difference ranking of all adjacent metal segments. A larger first gap can reduce capacitive coupling in the high-potential-difference region of the first group of adjacent metal segments, while a smaller second gap reduces the amount of metal removed from the low-sensitivity region of the second group of adjacent metal segments. Differentiated spacing effectively avoids processing the entire cutting path at the maximum slit width, thus preserving more metal material while improving RF parameters.

[0054] Combination Figure 3 In some possible embodiments, a tuning capacitor 60 is also connected between the first electrical connection point 31 and the second electrical connection point 32. The tuning capacitor 60 is used to compensate for the resonant frequency deviation caused by the characteristics of the metal material, the cutting path, the gap filling and the chip input capacitance. The tuning capacitor 60 is connected in parallel with the chip module 40. The tuning capacitor 60 is connected across the two electrical connection terminals of the metal antenna region 30. Changing its capacitance value can change the total equivalent capacitance of the RF circuit, thereby adjusting the resonant frequency and impedance characteristics of the RF circuit.

[0055] Preferably, the tuning capacitor 60 can be a single fixed capacitor, or it can be formed by two or more capacitors connected in series or parallel. In actual mass production, several discrete capacitance values ​​are preset through experiments. When producing different batches of metal smart cards, the sample cards of each batch are measured first, and the corresponding capacitor is selected according to the measured resonant frequency. Optionally, in some implementation scenarios, adjustable capacitors or capacitor networks with switchable capacitor branches are used, and the equivalent capacitance value can be adjusted after assembly. In addition, the tuning capacitor 60 is preferably located close to the chip module 40 to shorten the connection conductors and reduce unwanted parasitic parameters.

[0056] Preferably, the resonant frequency of the RF circuit formed by the metal antenna region 30 and the tuning capacitor 60 is located within the target communication frequency band of the chip module 40. This target communication frequency band can be a near-field communication band centered at 13.56 MHz, or other RF communication frequency bands supported by the chip module 40. The phrase "located within the target communication frequency band" can be determined based on the communication protocol, chip input characteristics, and product testing standards; it is not required that the resonant frequency be exactly the same as the nominal center frequency.

[0057] Specifically, during tuning, the frequency deviation is first measured without the tuning capacitor 60 or after the initial capacitor is installed, and then the capacitance of the tuning capacitor 60 is increased or decreased. After the resonant frequency enters the target communication frequency band, it is also necessary to check whether the chip module 40 can be stably powered on and complete communication, in order to avoid meeting the resonant frequency but still having an inappropriate impedance match.

[0058] Combination Figure 3 In some possible embodiments, a protection capacitor 70 is also included, which is connected in series with the chip module 40.

[0059] Preferably, under a preset wireless transducer frequency band and a preset external field strength, the input power transmitted to the chip module 40 via the protection capacitor 70 is not higher than the allowable input power of the chip module 40.

[0060] It should be noted that when the metal smart card is near the wireless transducer, the metal antenna area 30 may receive excessive energy. Since the metal antenna area 30 has a large conductive area, it may generate a high induced voltage in a strong external alternating magnetic field. If this energy directly enters the chip module 40, the chip rectifier circuit, input protection structure or other internal circuits in the chip module 40 may experience temperature rise or overload, and in severe cases, it may even cause overheating and burnout.

[0061] Therefore, in this embodiment, the protection capacitor 70 is connected in series in the radio frequency current path where the chip module 40 is located. Since the capacitor impedance changes with frequency, at the target communication frequency, the protection capacitor 70 can maintain the impedance that allows the communication signal to pass through, and form a relatively large impedance within the preset wireless transducer frequency band, limiting the current and power entering the chip module 40.

[0062] Optionally, the protection capacitor 70 is disposed between any antenna terminal of the chip module 40 and the corresponding electrical connection point; Optionally, the protection capacitors 70 are respectively disposed on both sides of the chip module 40; Of course, either the tuning capacitor 60 or the protection capacitor 70 can be present, or both can be present.

[0063] Furthermore, when designing the protection capacitor 70, the following steps are followed: first, select the wireless transducer frequency band, external field strength, and card placement state; then, measure or calculate the input power transmitted to the chip module 40 via the protection capacitor 70. Preferably, the input power does not exceed the allowable input power of the chip module 40. The allowable input power can be determined from the chip datasheet, chip supplier test data, or card reliability tests.

[0064] For example, the card can be placed flat on the surface of the wireless transducer coil, with the direction most likely to generate energy coupling as the test direction, and a rated field strength applied within a preset frequency band of 100 kHz to 300 kHz. The input power can be calculated by measuring the voltage, current, or equivalent load parameters at the input terminals of the chip module 40, or by using the temperature rise and protection status of the chip module 40 as supplementary evaluation methods. If the input power exceeds the allowable value, the capacitance of the protection capacitor 70 should be reduced, the number of series protection stages should be increased, or the equivalent impedance of the metal antenna region 30 should be adjusted.

[0065] Combination Figure 5 As one implementation method, a partitioned filling design is adopted. In this embodiment, a hollowed-out slit pattern 20 is formed by cutting in the metal body 10. The hollowed-out slit pattern 20 includes a first hollowed-out area 24 and a second hollowed-out area 25, such as... Figure 5 As shown in the partial schematic diagram, two hollow sections are formed by cutting between the metal body 10, where the gap on the left is the first hollow area 24 and the gap on the right is the second hollow area 25. This is because if the entire hollow gap pattern 20 uses the same filling material, the high electric field area may increase parasitic capacitance due to the large dielectric constant of the material, while the high stress area may crack due to the material being too hard or too brittle.

[0066] Therefore, in this embodiment, different filling structures are used for the first hollow area 24 and the second hollow area 25 according to their different regional functions: The first hollow area 24 is filled with a first insulating material 26; preferably, the first hollow area 24 corresponds to a region with a large potential difference between adjacent metal segments, a high electric field strength, or a high sensitivity to parasitic capacitance. The second cutout area 25 is provided with a buffer layer 27 located on one side of the cutout wall and a support layer 28 located on the side wall of the buffer layer 27; preferably, the second cutout area 25 corresponds to the edge connecting gap, the path turning position, the chip connection area, or the area with large bending stress. The dielectric constant of the first insulating material 26 is less than that of the support layer 28, and the elastic modulus of the buffer layer 27 is less than that of the support layer 28. The first insulating material 26 is selected from materials with lower dielectric constant and lower dielectric loss to maintain electrical isolation on both sides of the gap and reduce the influence of the filling material on the RF circuit parameters. The buffer layer 27 is made of a material with low elastic modulus to absorb relative displacement when the metal body 10 bends or undergoes temperature changes. The support layer 28 is made of a material with higher elastic modulus and higher strength to maintain the shape of the hollow area and the flatness of the card surface.

[0067] It should be noted that the dielectric constant of the first insulating material 26 is less than that of the support layer 28, indicating that the first insulating material 26 prioritizes radio frequency performance; the elastic modulus of the buffer layer 27 is less than that of the support layer 28, indicating that the buffer layer 27 prioritizes deformation absorption while the support layer 28 prioritizes structural support. The above material relationships do not require the first insulating material 26, the buffer layer 27, and the support layer 28 to have specific chemical compositions, as long as their dielectric and mechanical properties meet the corresponding relationships.

[0068] Below, two specific embodiments are listed for further description. It should be noted that these are only two preferred embodiments and should not be used as evidence to limit the scope of protection of this invention: Example 1: Combination Figure 1 This embodiment 1 provides a metal smart card in which the metal antenna region 30 is directly formed from the metal body 10. It can be used as a contactless smart card or a dual-interface smart card. It includes a metal body 10, a metal antenna region 30 formed from a part of the metal body 10, a chip module 40, a tuning capacitor 60, and a protection capacitor 70.

[0069] The metal body 10 is made of 304 stainless steel, with a length of 85.6 mm, a width of 54 mm, and a thickness of 0.35 mm. The metal body 10 serves both as the mechanical support structure of the card and as a continuous conductive material required to form the radio frequency antenna.

[0070] A hollowed-out slit pattern 20 is formed by cutting at a predetermined position on the metal body 10. The hollowed-out slit pattern 20 is distributed in half of the card, and this half position is defined as the metal antenna region 30. The continuous conductive material in the metal antenna region 30 is the stainless steel material retained after the metal body 10 is cut. The cutting operation does not remove a large area cavity from the metal body 10 for placing an independent coil, but forms a continuous slit with a smaller width, so that the retained metal strip has a predetermined current propagation path.

[0071] In this embodiment, a nanosecond fiber laser is used to process and form a hollow slit pattern 20. By adjusting the spot size and the number of scans, the slit width is preferably controlled between 0.08 mm and 0.18 mm. After cutting, slag and burrs are removed, and the cut edges are passivated.

[0072] The cutout pattern 20 includes a slot segment 21 that extends from near the end of the metal antenna region 30 to a short side of the metal body 10, preventing the metal portion surrounding the metal antenna region 30 from forming a complete closed conductive path. When an external card reader generates an alternating magnetic field, this slot segment 21 can effectively limit the formation of an uncontrolled closed current outside the metal antenna region 30, while also preserving the continuous radio frequency current path required by the metal antenna region 30 itself.

[0073] The metal antenna region 30 extends along a continuous curved path, which is essentially a cut-out shape. The cut-out creates a spiral path 22, thus forming the continuous curved path. The overall shape formed by the spiral path 22 can be approximately circular, approximately rectangular, rounded rectangle, or other winding shapes. Adjacent metal segments are separated by cut-out gaps. The continuous curved path can extend the RF current path within a limited card surface range to obtain an equivalent inductance that is compatible with the chip module 40.

[0074] Example 2: Combination Figure 4 This embodiment 2 provides a metal smart card in which the metal antenna region 30 is formed by a heterogeneous conductive material. This embodiment is applicable to situations where the outer layer of the card needs to be made of a metal material with high strength or a specific appearance, but the conductivity, machinability or radio frequency loss of the metal material is not suitable for directly forming all the antenna conductors.

[0075] The metal body 10 is made of titanium alloy plate, with a length of 85.6 mm, a width of 54 mm, and a thickness of 0.35 mm. A receiving area is formed at a designated position on the metal body 10, which is a mounting window penetrating the metal body 10. A second conductive material 50 is fixed within the receiving area. The second conductive material 50 is dissimilar to the metal body 10; optionally, it can be copper, a copper-nickel alloy, a silver alloy, or copper-plated stainless steel. Preferably, in this embodiment, a copper-nickel alloy sheet is used.

[0076] Furthermore, the second conductive material 50 is bonded to the receiving area of ​​the metal body 10 by an insulating layer with a thickness of 0.02 mm to 0.05 mm. Since the receiving area is completely cut out, the second conductive material 50 is bonded to the inside of the metal body 10 by coating an insulating layer around its sidewalls. The insulating layer prevents the current path used as an antenna in the second conductive material 50 from being directly short-circuited by the metal body 10, ensuring that the current in the antenna section flows only in the second conductive material 50.

[0077] A hollowed-out slit pattern 20 is formed on the second conductive material 50 by cutting. The hollowed-out slit pattern 20 defines a metal antenna region 30 in the second conductive material 50. The metal antenna region 30 is composed of the second conductive material 50, which is heterogeneous to the metal body 10. Furthermore, the first electrical connection point 31 and the second electrical connection point 32 are respectively disposed at the two ends of the continuous conductive path formed by the second conductive material 50 and are electrically connected to the two antenna ends of the chip module 40.

[0078] At least one slot segment 21 on the second conductive material 50 extends to the outer edge of the second conductive material 50 and communicates with a corresponding insulating opening on the metal body 10. The insulating opening on the metal body 10 continues to extend to the outer edge of the metal body 10. Through the communication between the slot segment 21 and the insulating opening, the hollow slot pattern 20 and the outer edge of the metal body 10 form a communication structure. This communication structure can effectively interrupt the closed conductive path formed by the metal body 10 and surrounding the metal antenna region 30, while preventing the metal body 10 from bridging the antenna slot on the second conductive material 50.

[0079] In summary, compared with the prior art, the above embodiments have at least the following technical advantages: 1. A hollowed-out pattern 20 with a certain design is formed by cutting and hollowing out the area defined by the metal smart card. The continuous conductive material formed after cutting is used to form the metal antenna area 30, so that the metal body 10 can simultaneously bear the functions of structural support and radio frequency antenna, reduce the space occupied by independent antennas, and improve the utilization rate of metal materials. 2. By setting a gap segment 21 that connects to the outer edge of the metal body 10, the closed conductive path surrounding the metal antenna area 30 is interrupted, reducing the electromagnetic loss generated by the closed metal loop and improving the stability of radio frequency communication. 3. The antenna forming method can be selected according to the different card structure requirements. The metal antenna region 30 can be formed by using the first conductive material 11 or the heterogeneous second conductive material 50 to improve design flexibility and adaptability. 4. By adopting a spiral path 22, a serpentine path 23, and a structure that adjusts the gap width according to the potential difference, the antenna electrical parameters can be adjusted while maintaining the continuity of the metal material, thereby improving the balance between antenna performance and mechanical performance. 5. By setting the tuning capacitor 60, the resonant frequency of the radio frequency circuit formed by the metal antenna area 30 is located in the target communication frequency band, thereby improving the communication efficiency between the chip module 40 and the card reader. 6. By setting a protection capacitor 70 connected in series with the chip module 40, the energy input to the chip module 40 is limited when the wireless power transducer generates a strong external field, thereby improving the chip module 40's ability to resist abnormal field strength. 7. By setting different filling structures for different hollow areas, the requirements for radio frequency performance and mechanical reliability can be met respectively, thereby improving the long-term stability of metal smart cards.

[0080] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A metal smart card, characterized in that, include: A metal body having a hollowed-out slit pattern formed by cutting, the hollowed-out slit pattern defining a metal antenna region at a predetermined position in the metal body, the metal antenna region being made of a continuous conductive material, and defining a first electrical connection point and a second electrical connection point within the metal antenna region. The perforated slit pattern is configured to include at least one slit segment that communicates with the outer edge of the metal body, for discontinuously surrounding the closed conductive path formed by the metal body surrounding the metal antenna region; A chip module, wherein the chip module is electrically connected to the first electrical connection point and the second electrical connection point respectively, such that the metal antenna region constitutes at least a portion of the conductive path of the radio frequency antenna of the chip module.

2. The metal smart card as described in claim 1, characterized in that, The continuous conductive material is the first conductive material retained after the metal body is cut.

3. The metal smart card as described in claim 1, characterized in that, The continuous conductive material is a second conductive material that is heterogeneous with the metal body, and a hollowed-out slit pattern is formed by cutting on the second conductive material.

4. The metal smart card as described in claim 1, characterized in that, The hollowed-out slit pattern extends along a continuous curved path, and at least a portion of the continuous curved path includes at least one of a spiral path that gradually unfolds around the central region and a serpentine path that extends back and forth along the length or width direction of the metal body.

5. The metal smart card as described in claim 4, characterized in that, The metal antenna region includes a first group of adjacent metal segments separated by a first gap and a second group of adjacent metal segments separated by a second gap; At the target communication frequency, the potential difference between the first group of adjacent metal segments is greater than the potential difference between the second group of adjacent metal segments; The width of the first gap is greater than the width of the second gap.

6. The metal smart card as described in claim 1, characterized in that, A tuning capacitor is also connected between the first electrical connection point and the second electrical connection point; The tuning capacitor is connected in parallel with the chip module.

7. The metal smart card as described in claim 1 or 6, characterized in that, It also includes a protection capacitor, which is connected in series with the chip module.

8. The metal smart card as described in claim 6, characterized in that, The resonant frequency of the radio frequency circuit formed by the metal antenna region and the tuning capacitor is located within the target communication frequency band of the chip module.

9. The metal smart card as described in claim 7, characterized in that, Under a preset wireless transducer frequency band and a preset external field strength, the input power transmitted to the chip module through the protection capacitor is not higher than the allowable input power of the chip module.

10. The metal smart card as described in claim 1, characterized in that, The hollowed-out pattern includes a first hollowed-out area and a second hollowed-out area; The first hollow area is filled with a first insulating material; The second hollow area is provided with a buffer layer located on one side of the hollow wall and a support layer located on the side wall of the buffer layer; The dielectric constant of the first insulating material is less than that of the supporting layer, and the elastic modulus of the buffer layer is less than that of the supporting layer.

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