Smart card
By introducing a high-pass filter into the smart card, the wireless charging carrier is filtered out using the high capacitance value of the capacitive filter module, the problem of damage to the smart card in a high-power charging environment is solved, and the effect of reducing the risk of damage and ensuring the normal operation of the chip is achieved.
Patent Information
- Application Number
- CN202421572323.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-04
- Publication Date
- 2025-04-29
- Estimated Expiration
- 2034-07-04
AI Technical Summary
When smart cards are exposed to high-power vehicle-mounted wireless charging environments for a long time, they are easily damaged by coil-coupled charging carriers and are difficult to recover.
A smart card is designed, including a chip, a capacitive filter module and an antenna module. The equivalent capacitance value of the capacitive filter module is greater than twice the equivalent capacitance value of the chip, forming a high-pass filter to filter out low-frequency wireless charging carriers and protect the chip from damage.
The design of the high-pass filter effectively reduces the risk of smart cards being damaged in low-frequency environments, while ensuring that the chip has less impact on its performance during normal operating frequency bands.
Smart Images
Figure CN222813152U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of identification cards, in particular to a smart card. Background Art
[0002] Smart cards can achieve contact or contactless communication with card readers and have important applications in the field of modern communication technology.
[0003] However, smart cards are often in a strong magnetic environment outside the working frequency band when in use. For example, in-vehicle wireless charging is often equipped with a high-power charger such as 50W. As a car key, the working frequency band of the smart card is different from the frequency band of wireless charging. When the smart card is exposed to a high-power in-vehicle wireless charging environment for a long time, it is easy to cause irreparable damage to the smart card due to the coupling of the charging carrier by the coil. Utility Model Content
[0004] The utility model provides a smart card to reduce the risk of smart card damage.
[0005] According to one aspect of the utility model, a smart card is provided, the smart card comprising: a chip, a capacitive filtering module and an antenna module;
[0006] The chip comprises a first antenna connection end and a second antenna connection end, the first antenna connection end is electrically connected to the first end of the antenna module through the capacitive filtering module, and the second antenna connection end is electrically connected to the second end of the antenna module;
[0007] Wherein, the equivalent capacitance value of the capacitive filtering module is greater than twice the equivalent capacitance value of the chip.
[0008] Optionally, the capacitive filtering module is used to filter out waves in a first preset frequency band and pass waves in a second preset frequency band; wherein the first preset frequency band is a wireless charging frequency band, and the second preset frequency band is an operating frequency band of the chip.
[0009] Optionally, the equivalent capacitance value of the capacitive filtering module is less than or equal to a preset capacitance threshold.
[0010] Optionally, a withstand voltage value of the capacitive filtering module is greater than or equal to a preset voltage threshold.
[0011] Optionally, the capacitive filtering module includes a filtering capacitor, a first end of the filtering capacitor is electrically connected to the first antenna connection end, and a second end of the filtering capacitor is electrically connected to the first end of the antenna module.
[0012] Optionally, the antenna module is a special-shaped antenna coil or a standard antenna coil.
[0013] Optionally, the antenna module is arranged around the chip and the capacitive filtering module.
[0014] Optionally, the operating frequency of the chip is 13.56 MHz; or, the chip is an RFID chip; or, the chip is an NFC chip.
[0015] Optionally, the smart card further comprises a shell, and the chip, the capacitive filtering module and the antenna module are arranged in the shell.
[0016] Optionally, the smart card is a car key.
[0017] The technical solution of the embodiment of the utility model adopts a smart card including a chip, a capacitive filter module and an antenna module; the chip includes a first antenna connection end and a second antenna connection end, the first antenna connection end is electrically connected to the first end of the antenna module through the capacitive filter module, and the second antenna connection end is electrically connected to the second end of the antenna module; wherein the equivalent capacitance value of the capacitive filter module is greater than twice the equivalent capacitance value of the chip. The capacitive filter module and the antenna module constitute a high-pass filter, which can filter out low frequencies, thereby reducing the risk of damage to the smart card when it is in a low-frequency environment for a long time. In addition, the setting of the capacitance value of the capacitive filter module makes the equivalent capacitance of the smart card closer to the equivalent capacitance of the chip, thereby having less impact on the performance of the chip when working in the normal working frequency band.
[0018] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present utility model, nor are they intended to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0020] Figure 1 A schematic diagram of a circuit structure of a smart card provided by an embodiment of the utility model;
[0021] Figure 2 A schematic diagram of an equivalent circuit of a smart card provided by an embodiment of the utility model;
[0022] Figure 3 A test diagram of a smart card in a normal working frequency band provided by an embodiment of the utility model;
[0023] Figure 4A filter performance test diagram of a smart card provided by an embodiment of the utility model;
[0024] Figure 5 A graph showing the relationship between the equivalent capacitance value of a capacitive filter module and the performance of a smart card provided in an embodiment of the utility model;
[0025] Figure 6 A schematic diagram of the structure of a smart card provided in an embodiment of the utility model. DETAILED DESCRIPTION
[0026] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.
[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0028] Figure 1 A schematic diagram of a circuit structure of a smart card provided by an embodiment of the utility model, Figure 2 This is a schematic diagram of an equivalent circuit of a smart card provided by an embodiment of the utility model, referring to Figure 1 and Figure 2 The smart card includes: a chip 11, a capacitive filtering module 12 and an antenna module 13; the chip 11 includes a first antenna connection terminal VA and a second antenna connection terminal VB; the first antenna connection terminal VA is electrically connected to a first end of the antenna module 13 through the capacitive filtering module 12, and the second antenna connection terminal VB is electrically connected to a second end of the antenna module 13; the equivalent capacitance value of the capacitive filtering module 12 is greater than twice the equivalent capacitance value of the chip 11.
[0029] Specifically, the smart card is, for example, a car key, an ID card, a financial card, a social security card, an access card, a bus card, a subway card, or an RFID (Radio Frequency Identification) electronic tag. The smart card can communicate with the card reader in contact or contactless form. The chip 11 in the smart card corresponds to a chip with different functions depending on the type of smart card. The chip 11 is used to decode the information transmitted by the card reader and output relevant information to the card reader according to the decoded instructions. The antenna module 13 is used to receive the information transmitted by the card reader and radiate the information sent by the chip 11 to the outside so that the card reader can read it.
[0030] like Figure 2 As shown, the chip 11 can be equivalent to an equivalent chip resistor R1 and an equivalent chip capacitor C2 connected in series between the first antenna connection terminal VA and the second antenna connection terminal VB. The antenna module can be equivalent to an inductor L1. The first antenna connection terminal VA and the second antenna connection terminal VB can be pads on the chip 11 for connecting the antenna. The operating frequency band of the smart card is usually higher, while the frequency band of wireless charging is usually lower. Therefore, in this embodiment, by connecting the capacitive filter module 12 in series between the first antenna connection terminal VA and the first end of the antenna module 13, the capacitive filter module 12 has the function of passing AC and blocking DC, that is, the higher the frequency, the better the passability, and the lower the frequency, the worse the passability. The capacitive filtering module 12 and the antenna module 13 are equivalent to high-pass filters. The relatively low-frequency wireless charging carrier coupled to the antenna module 13 is filtered out by the capacitive filtering module 12, so that the wireless charging carrier will not have or very little signal will be transmitted to the first antenna connection terminal VA and the second antenna connection terminal VB of the chip 11. The amplitude of the wireless charging carrier received by the first antenna connection terminal VA and the second antenna connection terminal VB is much smaller than the withstand voltage value that can be tolerated, and the energy transmitted to the chip 11 is also small. The chip 11 will not be damaged by the interference of the wireless charging carrier, thereby reducing the risk of damage to the smart card.
[0031] In addition, after the capacitive filter module 12 is added, if the parameters of the capacitive filter module 12 are not restricted, although the low frequency can be filtered out, it will also affect the high-frequency signal, thereby affecting the normal operation of the chip 11. In this embodiment, the equivalent capacitance value of the capacitive filter module 12 is set to be greater than twice the equivalent capacitance value of the chip 11, so that the capacitor constituting the high-pass filter in the smart card is mainly the capacitive filter module 12, and the chip 11 contributes less to the high-pass filter. In other words, most of the wireless charging carrier is attenuated by the capacitive filter module 12, and only a very small part or no wireless charging carrier can be transmitted to the equivalent capacitor of the chip 11, so the filtering effect is better. On the other hand, the equivalent capacitance value of the capacitive filtering module 12 is set to be greater than twice the equivalent capacitance value of the chip 11. According to the capacitance calculation formula of the series capacitor, the equivalent capacitance value of the capacitive filtering module 12 and the chip 11 after being connected in series is greater than 2 / 3 of the equivalent capacitance value of the chip 11, that is, the final capacitance is closer to the equivalent capacitance of the chip 11, and thus the impact on the chip 11 when working in the normal working frequency band is small, thereby ensuring the normal working performance of the smart card.
[0032] The technical solution of this embodiment adopts a smart card including a chip, a capacitive filter module and an antenna module; the chip includes a first antenna connection end and a second antenna connection end, the first antenna connection end is electrically connected to the first end of the antenna module through the capacitive filter module, and the second antenna connection end is electrically connected to the second end of the antenna module; wherein the equivalent capacitance value of the capacitive filter module is greater than twice the equivalent capacitance value of the chip. The capacitive filter module and the antenna module constitute a high-pass filter, which can filter out low frequencies, thereby reducing the risk of damage to the smart card when it is in a low-frequency environment for a long time. In addition, the setting of the capacitance value of the capacitive filter module makes the equivalent capacitance of the smart card closer to the equivalent capacitance of the chip, thereby having less impact on the performance of the chip when working in the normal working frequency band.
[0033] Optionally, the capacitive filtering module 12 is used to filter out waves in a first preset frequency band and pass waves in a second preset frequency band; wherein the first preset frequency band is a wireless charging frequency band, and the second preset frequency band is a working frequency band of the chip 11 .
[0034] Specifically, the operating frequency band of the chip 11 is, for example, 13.56MHz specified in the ISO-14443 standard. The wireless charging frequency band is, for example, less than 200kHz, for example, a frequency band of 120kHz±12kHz. The frequency of the operating frequency band of the chip 11 is much larger than the wireless charging frequency band. Therefore, the capacitive filtering module 12 is provided in this embodiment to form a high-pass filter, which can greatly reduce the impact of the wireless charging frequency band on the chip, while having little impact on the frequency band of the normal operation of the chip 11. It should be noted that the first preset frequency band may also be other frequency bands, and the second preset frequency band may also be other frequency bands. The frequency of the first preset frequency band is less than the frequency of the second preset frequency band.
[0035] Optionally, the equivalent capacitance value of the capacitive filtering module 12 is less than or equal to a preset capacitance threshold.
[0036] Specifically, the preset capacitance threshold is, for example, 200pF. When the equivalent capacitance value of the capacitive filtering module 12 is large, such as exceeding the preset capacitance threshold, the response time of the smart card will be slowed down, and there may also be a risk of signal distortion. Therefore, in this embodiment, the equivalent capacitance value of the capacitive filtering module 12 is set to be less than the preset capacitance threshold, which can ensure the filtering effect of the low-frequency signal without slowing down the response time of the smart card, and the risk of signal distortion is also low.
[0037] For example, when the smart card is a car key, the chip 11 may be a THD89 chip, and the equivalent capacitance value of the chip 11 is about 24 pF. Then, the equivalent capacitance value of the capacitive filter module 12 is greater than 48 pF and less than 200 pF. The equivalent capacitance value of the capacitive filtering module 12 is, for example, 49pF, 50pF, 55pF, 56pF, 60pF, 66pF, 70pF, 76pF, 80pF, 86pF, 90pF, 96pF, 100pF, 106pF, 110pF, 116pF, 120pF, 126pF, 130pF, 136pF, 140pF, 146pF, 150pF, 156pF, 160pF, 166pF, 170pF, 176pF, 180pF, 186pF, 190pF, 196pF or 200pF.
[0038] Optionally, the equivalent capacitance value of the chip 11 may be obtained from parameters of the chip 11 or obtained by testing, etc., which is not specifically limited in this embodiment.
[0039] Optionally, in the present embodiment, the equivalent capacitance value of the capacitive filter module 12 can reach the required value by setting the facing area of the plates of the capacitive filter module 12, the material of the medium, or the distance between the plates. When designing, the specific size of the capacitive filter module 12 can be determined by comprehensively considering the size and thickness of the smart card. Preferably, the facing area of the plates is taken as a consideration, that is, if the size of the smart card is large, the facing area of the plates of the capacitive filter module is also set to be large, and its thickness is set to be thicker. If the corresponding capacitance value cannot be achieved when the facing area of the plates of the capacitive filter module is large, consider reducing the distance between the plates.
[0040] Optionally, a withstand voltage value of the capacitive filtering module is greater than or equal to a preset voltage threshold.
[0041] Specifically, the preset voltage threshold can be determined according to the voltage peak value corresponding to the first preset frequency band, such as the preset voltage threshold is greater than the voltage peak value corresponding to the first preset frequency band. When the first preset frequency band is the frequency band corresponding to wireless charging, its voltage peak value is about 30V, then the preset voltage threshold is greater than 30V. Exemplarily, the preset voltage threshold can be 35V, 40V, 45V or 50V, etc. The withstand voltage value of the capacitive filter module can be controlled by selecting parameters such as the dielectric material and dielectric thickness of the capacitive filter module.
[0042] Optionally, in some embodiments, the capacitive filtering module 12 includes a filtering capacitor C1, a first end of the filtering capacitor C1 is electrically connected to the first antenna connection terminal VA, and a second end of the filtering capacitor C1 is electrically connected to the first end of the antenna module 13. In this embodiment, the function of the capacitive filtering module 12 can be realized by using a capacitor, the circuit structure is simple, and it is helpful to reduce the cost of the smart card. Of course, in some other embodiments, the capacitive filtering module 12 can also be composed of a circuit that can be equivalent to a capacitor.
[0043] For example, Figure 3 A test diagram of a smart card in a normal working frequency band provided by an embodiment of the utility model, Figure 4 A filter performance test diagram of a smart card provided by the embodiment of the utility model, referring to Figure 3 and Figure 4 In this embodiment, taking the equivalent capacitance value of the capacitive filter module 12 as 56pF and the equivalent capacitance value of the chip 11 as 24pF as an example, the performances when the capacitive filter module is added and when the capacitive filter module is not added are tested respectively, wherein: Figure 3 Only the result graph at 10dBm is shown. Figure 4 Figure a shows the waveform of the chip received in the wireless charging carrier environment when the capacitive filtering module is not added, where the horizontal axis represents time and the vertical axis represents the amplitude of the waveform, with a peak-to-peak value of about 14.7V and a frequency of about 141.72kHz, which means it has a large energy; Figure b shows the waveform of the carrier received by the chip in the wireless charging carrier environment after the capacitive filtering module is added, where the horizontal axis represents time and the vertical axis represents the amplitude of the waveform, with a peak-to-peak value of about 4.65V and a frequency of about 144.26kHz. Figure 3 and Figure 4 It can be seen that after adding the capacitive filtering module, the wireless charging working frequency band can be effectively filtered out, and the impact on the normal operation of the chip 11 is small.
[0044] For example, Figure 5 A graph showing the relationship between the equivalent capacitance value of a capacitive filter module and the performance of a smart card provided by an embodiment of the utility model. The performance of the smart card is reflected by the peak-to-peak value of the coil-coupled charging carrier. The lower the peak-to-peak value, the worse the performance. Figure 5It can be seen that when the capacitance value of the capacitive filter module does not exceed 48pF, the performance of the smart card in normal operation is poor; when the capacitance value of the capacitive filter module is greater than 48pF and less than 200pF, the normal working performance of the smart card is almost unaffected; and when the capacitance value of the capacitive filter module is greater than 200pF, the filtering performance is far less than expected.
[0045] Optionally, in some embodiments, the chip 11 is a chip that supports the 13.56MHz carrier standard, and the corresponding chip 11 supports the standard RF interface of the 13.36MHz carrier. In this case, the antenna module 13 can be an antenna coil that complies with the ISO-14443 standard. In some embodiments, the chip 11 is an RFID electronic tag. In this case, the antenna module 13 can be a special-shaped antenna coil, that is, a special-shaped coil of non-standard size. In some embodiments, the chip 11 is a standard NFC (Near Field Communication) chip. In this case, the antenna module 13 can be an antenna coil corresponding to the NFC chip in a handheld terminal device such as a mobile phone or mPOS.
[0046] Optionally, in some embodiments, the antenna module 13 may be a standard antenna coil or a special-shaped antenna coil. The shape of the antenna module 13 may be set according to the shape of the chip or smart card, that is, the shape of the coil in the antenna module 13 is the same as the shape of the chip or smart card. If the shape of the chip is special-shaped, the shape of the antenna coil is also special-shaped. Alternatively, if the shape of the smart card is special-shaped, the shape of the antenna coil is also special-shaped.
[0047] Optionally, Figure 6 A schematic diagram of a smart card structure provided by an embodiment of the utility model, referring to Figure 6 The antenna module 13 is disposed around the chip 11 and the capacitive filter module 12 .
[0048] Specifically, the antenna module 13 may be an antenna coil, which may be arranged at the edge of the smart card, while the chip 11 and the capacitive filter module 12 are arranged at the center of the smart card. This arrangement may make it easier for the antenna module 13 to receive and send signals.
[0049] Optionally, continue to refer to Figure 6 The smart card further includes a housing 14; the chip 11, the capacitive filter module 12 and the antenna module 13 are arranged in the housing 14. Specifically, the housing 14 can be made of PVC or ABS. The housing 14 can protect the chip 11, the capacitive filter module 12 and the antenna module 13, prevent the above modules from being corroded by water, oxygen and the like, and extend the service life of the smart card.
[0050] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.
[0051] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.
Claims
1. A smart card, characterized in that: The smart card includes: a chip, a capacitive filtering module and an antenna module; The chip comprises a first antenna connection end and a second antenna connection end, the first antenna connection end is electrically connected to the first end of the antenna module through the capacitive filtering module, and the second antenna connection end is electrically connected to the second end of the antenna module; Wherein, the equivalent capacitance value of the capacitive filtering module is greater than twice the equivalent capacitance value of the chip.
2. The smart card according to claim 1, characterized in that: The capacitive filtering module is used to filter out waves in a first preset frequency band and pass waves in a second preset frequency band; wherein the first preset frequency band is a wireless charging frequency band, and the second preset frequency band is a working frequency band of the chip.
3. The smart card according to claim 2, characterized in that: The equivalent capacitance value of the capacitive filtering module is less than or equal to a preset capacitance threshold.
4. The smart card according to claim 1, characterized in that: The withstand voltage value of the capacitive filtering module is greater than or equal to a preset voltage threshold.
5. The smart card according to claim 1, characterized in that: The capacitive filtering module includes a filtering capacitor, a first end of the filtering capacitor is electrically connected to the first antenna connection end, and a second end of the filtering capacitor is electrically connected to the first end of the antenna module.
6. The smart card according to claim 1, characterized in that: The antenna module is a special-shaped antenna coil or a standard antenna coil.
7. The smart card according to claim 6, characterized in that: The antenna module is arranged around the chip and the capacitive filtering module.
8. The smart card according to claim 1, characterized in that: The operating frequency of the chip is 13.56 MHz; or, the chip is an RFID chip; or, the chip is an NFC chip.
9. The smart card according to claim 1, characterized in that: The smart card further comprises a shell, and the chip, the capacitive filtering module and the antenna module are arranged in the shell.
10. The smart card according to claim 1, characterized in that: The smart card is a car key.