Patent Publication Number: US-2023138140-A1

Title: Near field communication tag and control system for near field communication tag

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Chinese Patent Application No. 202010090435.5 filed in China on Feb. 13, 2020, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to the technical field of electronic tags, and in particular to a Near Field Communication (NFC) tag and a control system for the NFC tag. 
     BACKGROUND 
     Currently, NFC tags are generally battery-powered, which is characterized by operation with power consumption. Even in the case of low frequency operation, the battery may only maintain a low power consumption operation time of about five years. In most cases, the tag is discarded after the battery is exhausted, resulting in serious waste of resources and damage to the environment. For this reason, in the related art, a rechargeable lithium battery is used to extend the operation time of the tag as far as possible, and the operating cost is reduced by reducing the frequency for replacing the battery. However, with the progress of science and technology, the prominent energy problem, the lack of resources, etc., the energy consumption of the NFC tag of the related art is still relatively high, which does not meet the energy-saving and environmental-friendly requirements for NFC tags, and the user experience is poor. 
     SUMMARY 
     In a first aspect, embodiments of the present disclosure provide a NFC tag, including: a NFC coil, a control circuit, an energy acquisition circuit, and an energy storage circuit, wherein 
     the NFC coil is configured to detect a magnetic field signal transmitted by a card reader when a distance between the NFC tag and the card reader is within a predetermined distance range; 
     the energy acquisition circuit is configured to convert the magnetic field signal into an electrical signal when the NFC coil detects the magnetic field signal; and 
     the control circuit is configured to control the energy acquisition circuit to transmit the electrical signal to the energy storage circuit, and control to charge the energy storage circuit through the electrical signal. 
     Optionally, the energy acquisition circuit is connected to the NFC coil and the control circuit, respectively, and the energy storage circuit is connected to the energy acquisition circuit and the control circuit, respectively. 
     Optionally, the energy acquisition circuit includes: 
     an energy conversion sub-circuit, wherein the energy conversion sub-circuit is connected to the NFC coil and the control circuit, respectively, the energy conversion sub-circuit is configured to convert the magnetic field signal into the electrical signal when the NFC coil detects the magnetic field signal, and the control circuit is configured to control the energy conversion sub-circuit to transmit the electrical signal to the energy storage circuit; and 
     a first switching sub-circuit, wherein the first switching sub-circuit is connected to the energy conversion sub-circuit and the energy storage circuit, respectively, and the first switching sub-circuit is configured to electrically connect the energy conversion sub-circuit to the energy storage circuit, or electrically disconnect the energy conversion sub-circuit from the energy storage circuit. 
     Optionally, the NFC tag further includes: an electronic ink display screen, wherein the electronic ink display screen is connected to the control circuit, the control circuit is configured to control the NFC tag to perform data transmission with the card reader upon detecting that a voltage of the energy storage circuit reaches a rated voltage, and refresh display content of the electronic ink display screen after the data transmission has been performed. 
     Optionally, the control circuit is connected to the first switching sub-circuit, and the control circuit is further configured to: 
     control the first switching sub-circuit to electrically disconnect the energy conversion sub-circuit from the energy storage circuit after the display content of the electronic ink display screen has been refreshed. 
     Optionally, the NFC tag further includes: 
     a second switching circuit, wherein the second switching circuit is connected to the energy storage circuit and the electronic ink display screen, respectively, and the second switching circuit is configured to electrically connect the energy storage circuit to the electronic ink display screen or electrically disconnect the energy storage circuit from the electronic ink display screen. 
     Optionally, the control circuit is connected to the second switching circuit, and the control circuit is further configured to: 
     control the second switching circuit to electrically connect the electronic ink display screen to the energy storage circuit after the data transmission has been performed. 
     Optionally, the NFC tag further includes: 
     a state storage circuit; 
     the control circuit is further configured to: identify the card reader through the energy conversion sub-circuit when the distance between the NFC tag and the card reader is within the predetermined distance range, determine whether the NFC tag is matched with the card reader, update a flag bit state in the state storage circuit to be a state of waiting for being charged when the NFC tag is matched with the card reader; update the flag bit state in the state storage circuit to be a charging completion state upon detecting that the voltage of the energy storage circuit reaches the rated voltage; and update the flag bit state in the state storage circuit to be a refreshing success state after the display content of the electronic ink display has been refreshed. 
     Optionally, the energy storage circuit is a supercapacitor. 
     Optionally, the first switching sub-circuit and/or the second switching circuit is a metal oxide semiconductor field effect transistor. 
     Optionally, the state storage circuit is an electrically erasable programmable read only memory. 
     In a second aspect, the embodiments of the present disclosure provide a control system of a NFC tag, including: a card reader and the NFC tag provided in the embodiments of the first aspect of the present disclosure. 
     Optionally, the card reader is a mobile terminal having a NFC function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a structural block diagram of a NFC tag according to an embodiment of the present disclosure; 
         FIG.  2    is a structural block diagram of a NFC tag according to an embodiment of the present disclosure; 
         FIG.  3    is a structural block diagram of a NFC tag according to another embodiment of the present disclosure; 
         FIG.  4    is a structural block diagram of a NFC tag according to yet another embodiment of the present disclosure; 
         FIG.  5    is a schematic structural diagram of a NFC tag according to a specific embodiment of the present disclosure; 
         FIG.  6    is a schematic flowchart diagram of image data transmission between a mobile phone and a NFC tag according to a specific embodiment of the present disclosure; and 
         FIG.  7    is a structural block diagram of a control system of a NFC tag according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be described in detail below, examples of the embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar parts or parts having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present disclosure and are not to be construed as limiting the present disclosure. 
     Hereinafter, a NFC tag and a control system for the NFC tag according to the embodiments of the present disclosure will be described with reference to the accompanying drawings. 
       FIG.  1    is a structural block diagram of a NFC tag according to an embodiment of the present disclosure. 
     As shown in  FIG.  1   , the NFC tag  100  includes: a NFC coil  10 , an energy acquisition circuit  20 , an energy storage circuit  30 , and a control circuit  50 . 
     The NFC coil  10  is configured to detect a magnetic field signal when a card reader  200  is within a set range; the energy acquisition circuit  20  is connected to the NFC coil  10  and the control circuit  50 , respectively, the energy acquisition circuit  20  is configured to convert the magnetic field signal detected by the NFC coil  10  into an electrical signal when the NFC coil  10  detects the magnetic field signal; the energy storage circuit  30  is connected to the energy acquisition circuit  20  and the control circuit  50 , respectively, and the control circuit  50  is configured to control the charging of the energy storage circuit  30  with the electrical signal. 
     Specifically, in practical applications, when the card reader  200  is located within the set range near the NFC coil  10 , the card reader  200  initiates magnetic induction, so that the NFC coil  10  may detect the magnetic field signal and transmit the magnetic field signal to the energy acquisition circuit  20 , the energy acquisition circuit  20  converts the magnetic field signal into an electrical signal and transmits the electrical signal to the energy storage circuit  30  under the control of the control circuit  50 ; and the control circuit  50  controls the energy storage circuit  30  to store electric energy in a wireless charging manner under the effect of the electric signal. 
     It should be noted that, in the embodiment of the present disclosure, the energy acquisition circuit  20  has a NFC function. The card reader  200  may be, for example, a mobile terminal (e.g. a mobile phone or a Personal Digital Assistant (PDA)) having a NFC function; in other words, the card reader  200  may include a NFC chip, and when the card reader  200  is located within the set range near the NFC coil  10 , the card reader  200  may read relevant information from the NFC tag  100  if required, so as to perform data transmission, thereby realizing the data transmission from the NFC tag  100  to the card reader  200 , and accordingly, the card reader  200  reads the data transmitted by the NFC tag  100 . The above set range may be an effective distance for initiating magnetic induction between the card reader  200  and the NFC tag  100 . The effective distance may be determined according to the actual situation, and may be, for example, a distance in the range of 1 cm to 10 cm. 
     In general, the NFC tag  100  does not require power supply of the battery, the energy storage circuit  30  stores electric energy in a wireless charging manner, and the NFC tag  100  is powered through the electric energy stored in the energy storage circuit  30  so as to enable the NFC tag  100  to operate properly. As compared with the method of using a battery to power the NFC tag  100  in the related art, resource waste may be reduced, environmental damage may be reduced, cost may be reduced, and energy may be saved and environmental protection may be improved. 
     Thus, the energy storage circuit is charged under the action of the magnetic field signal to realize wireless charging, which does not require the power supply of the battery, and is more energy-saving and environmental-friendly, and has the advantages of low cost and low power consumption. 
     It should be noted that in the related art, a user usually needs to manually turn on a charging circuit of the communication tag  100  before charging the NFC tag  100 . However, when the user wants to continue to charge the communication tag  100  after the charging is interrupted (e.g. an electronic device for charging is electrically disconnected), the user has to manually turn on the charging circuit of the communication tag  100  again, resulting in high frequency of the user operation and reducing the user experience. In contrast, in the embodiments of the present disclosure, the energy storage circuit  30  acquires a current signal (micro-current) so as to perform wireless charging, and it does not require the user to manually turn on the charging circuit. However, when the energy storage circuit  30  is a supercapacitor, if a charged device forms a return circuit, the supercapacitor will self-discharge, and if the charging circuit is not timely turned off, the supercapacitor will self-discharge to be at 0 V, resulting in a longer time for the next charging and reducing the user experience. 
     In order to solve this technical problem, in the embodiments of the present disclosure, it may automatically turn on and turn off the charging circuit (a first switching sub-circuit  22  is further provided in the energy acquisition circuit  20 ), to improve the user experience, which will be described in details below in conjunction with  FIGS.  2  to  5   . 
     In an embodiment of the present disclosure, as shown in  FIG.  2   , the energy acquisition circuit  20  may include: an energy conversion sub-circuit  21  and a first switching sub-circuit  22 . 
     The energy conversion sub-circuit  21  is connected to the NFC coil  10  and the control circuit  50 , respectively, and the energy conversion sub-circuit  21  is configured to convert the magnetic field signal detected by the NFC coil  10  into the electrical signal when the NFC coil detects the magnetic field signal; the control circuit  50  is configured to control the energy conversion sub-circuit  21  to transmit the electrical signal to the energy storage circuit  30 ; the first switching sub-circuit  22  is connected to the energy conversion sub-circuit  21  and the energy storage circuit  30 , respectively, and the first switching sub-circuit  22  is configured to electrically connect the energy conversion sub-circuit  21  to the energy storage circuit  30  or electrically disconnect the energy conversion sub-circuit  21  fro, the energy storage circuit  30 . 
     In an example, referring to  FIG.  2   , the NFC tag  100  may further include an electronic ink display screen  40 . The control circuit  50  is connected to the electronic ink display screen  40 , the control circuit  50  is configured to control the NFC tag  100  to perform data transmission with the card reader  200  when detecting that the voltage of the energy storage circuit  30  reaches a rated voltage, and refresh the display content of the electronic ink display screen  50  after the data transmission is complete. 
     Further, referring to  FIG.  2   , the control circuit  50  is connected to the first switching sub-circuit  22 , and the control circuit  50  is further configured to: control the first switching sub-circuit  22  to electrically disconnect the energy conversion sub-circuit  21  from the energy storage circuit  30  after refreshing the display content of the electronic ink display screen  40 . 
     Specifically, in practical applications, when the card reader  200  is within the set range near the NFC coil  10 , the NFC coil  10  detects a magnetic field signal and transmits the detected magnetic field signal to the energy conversion sub-circuit  21 . The energy conversion sub-circuit  21  converts the received magnetic field signal into an electric signal, and when a voltage value of the electric signal is greater than a pre-set value (e.g. 1.8 V), the control circuit  50  starts to operate. At this moment, the control circuit  50  may control the first switching sub-circuit  22  to turn on, so that the first switching sub-circuit  22  electrically connects the energy conversion sub-circuit  21  to the energy storage circuit  30 , and then the energy storage circuit  30  stores energy in a wireless charging manner under the action of the electric signal. In the energy storage process, the control circuit  50  may detect the voltage of the energy storage circuit  30  in real time, and control the NFC tag  100  to perform data transmission with the card reader  200  when the voltage reaches the rated voltage (e.g. 1.8 V), that is, at this moment, data transmission is performed while charging the energy storage circuit  30 . After the control circuit  50  has detected that the data transmission is completed, the control circuit  50  may control the electronic ink display screen  40  to refresh the display content, that is, the electric power of the energy storage circuit  30  enables the electronic ink display screen  40  to refresh the display content so that the electronic ink display screen  40  displays the transmitted data. In the refreshing process, the control circuit  50  may detect whether the refreshing is completed in real time, and when the refreshing is completed, the control circuit  50  controls the first switching sub-circuit  22  to electrically disconnect the energy conversion sub-circuit  21  from the energy storage circuit  30  so as to timely switch off the charging circuit, thereby reducing the power consumption thereof, and ensuring that the power of the energy storage circuit  30  does not start from 0 V at the next charging. 
     In this example, referring to  FIG.  2   , communication between the control circuit  50  and the electronic ink display screen  40  may be implemented through a Serial Peripheral Interface (SPI). The energy conversion sub-circuit  21  may include a tag chip of ST25DV series, the tag chip may include an I2C (Inter-Integrated Circuit) interface; and is connected to the control circuit  50  through this interface, that is, communication between the control circuit  50  and the energy conversion sub-circuit  21  may be implemented through the I2C bus. 
     Thus, when the refreshing is completed, the charging circuit is electrically disconnected in time to reduce the self-discharge of the energy storage circuit, reduce the next charging period and improve the user experience. 
     In an embodiment of the present disclosure, as shown in  FIG.  3   , the NFC tag  100  may further include a second switching circuit  60 . The second switching circuit  60  is connected to the energy storage circuit  30  and the electronic ink display screen  40 , respectively, and the second switching circuit  60  is configured to electrically connect the energy storage circuit  30  to the electronic ink display screen  40  or electrically disconnect the energy storage circuit  30  from the electronic ink display screen  40 . 
     Further, referring to  FIG.  3   , the control circuit  50  is connected to the second switching circuit  60 , and the control circuit  50  is further configured to: control the second switching circuit  60  to electrically connect the energy storage circuit  30  to the electronic ink display screen  40  after the data transmission has been performed. 
     Specifically, after the data transmission has been performed, the control circuit  50  may detect whether the voltage of the energy storage circuit  30  reaches a rated voltage (e.g. 2.3 V) of the electronic ink display screen  40 , control the second switching circuit  60  to be turned on when the rated voltage (e.g. 2.3 V) of the electronic ink display screen  40  is reached, so that the energy storage circuit  30  powers the electronic ink display screen  40 , and at the same time, the control circuit  50  controls the electronic ink display screen  40  to refresh the display content, so that the electronic ink display screen  40  displays the transmitted data. 
     In this example, the first switching sub-circuit  22  and/or the second switching circuit  60  may be a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). Referring to  FIG.  3   , the energy storage circuit  23  may output a voltage between 2.3 V and 3 V to the electronic ink display screen  40  to power the electronic ink display screen  40 . 
     In an embodiment of the present disclosure, as shown in  FIG.  4   , the NFC tag  100  may further include a state storage circuit  70 . The control circuit  50  may further be configured to: when the card reader  200  is within the set range near the NFC coil  10  and the control module  50  starts to operate, identify the card reader  200  via the energy conversion sub-circuit  21 , determine whether the NFC tag  100  is matched with the card reader  200 , update a flag bit state in the state storage circuit  70  to a charging waiting state when the NFC tag is successfully matched with the card reader, update the flag bit state in the state storage circuit  70  to a charging completion state when detecting that the voltage of the energy storage circuit  30  reaches the rated voltage, and update the flag bit state in the state storage circuit  70  to a refreshing success state after refreshing the display content of the electronic ink display screen  40 . 
     Specifically, referring to  FIG.  4   , the control circuit  50  may be connected to the state storage circuit  70  to update the flag bit state in the state storage circuit  70 , wherein the flag bit state may indicate a current operating state of the NFC tag  100 . The state storage circuit  70  may not only support fast transmission (e.g. 26.5 Kbps) mode data transmission, but may also have a storage space of 8 Kbit Electrically Erasable Programmable Read Only Memory (EEPROM). The card reader  200  and the NFC tag  100  may agree to update the current state at a designated storage address of the storage space, and the storage space may be encrypted and protected by a password of 64 bits; only the control circuit  50  of the NFC tag  100  and the corresponding card reader  200  may access the encrypted storage space. 
     Specifically, when the card reader  200  is within the set range near the NFC coil  10  and the control circuit  50  starts to operate, the card reader  200  is identified and matched by the energy conversion sub-circuit  21  so as to identify and verify whether the energy conversion sub-circuit  21  is accurately matched to the corresponding card reader  200 , and a verification result is transmitted to the control circuit  50 ; if the card reader  200  is matched, it indicates that the matching is successful; the control circuit  50  updates the flag bit state in the state storage circuit  70  to the state for waiting to be charged when the NFC tag is matched with the card reader, updates the flag bit state in the state storage circuit  70  to the charging completion state when detecting that the voltage of the energy storage circuit  30  reaches the rated voltage; at this time, the card reader  200  may prompt a user to perform data transmission, and after the data transmission has been performed and the display content of the electronic ink display screen  40  is refreshed, the control circuit  50  updates the flag bit state in the state storage circuit  70  to the refreshing success state; at the same time, a display interface of the card reader  200  may display that the refreshing is successful to prompt the user that the NFC tag  100  is successfully refreshed. When the output voltage of the energy conversion sub-circuit  21  is greater than 1.8 V, the control circuit  50  starts to operate. 
     Thus, the NFC tag  100 , in combination with the NFC-specific security encryption mechanism, perform encryption protection on the state updating process, prevent the state from being lost or erroneously changed, and increase the stability during refreshing. 
     In a specific embodiment of the present disclosure, as shown in  FIG.  5   , each of the first switching sub-circuit  22  and the second switching circuit  60  is a P-channel MOS transistors (including a source electrode S, a gate electrode G and a drain electrode D), the energy storage circuit  30  may be a supercapacitor C, the control circuit  50  may be a Single Chip Microcomputer (MCU) such as a single chip computer of STM8L series, and the card reader  200  may be a mobile phone having a NFC function. 
     In practical applications, when a mobile phone is close to the NFC tag  100  and is located within the set range near the NFC coil  10 , the NFC coil  10  acquires a magnetic field signal and transmits the magnetic field signal to the energy conversion sub-circuit  21 , so that the energy conversion sub-circuit  21  converts the magnetic field signal into an electrical signal, and outputs a voltage V_EH to the MCU. When the MCU detects that the voltage V_EH is greater than 1.8 V, the MCU starts to operate, at this moment, the MCU identifies and matches the mobile phone via the energy conversion sub-circuit  21 , pulls up a General Purpose Input Output (GPIO) port on the left side of the MCU controlled by the first switching sub-circuit  22  when the matching is successful; and then the MCU controls the first switching sub-circuit  22  to be turned on so as to turn on the charging circuit, so that the energy conversion sub-circuit  21  charges the supercapacitor C via the first switching sub-circuit  22 . In the charging process, the MCU starts to perform data transmission with the mobile phone when the MCU detects that the voltage of the supercapacitor C reaches the rated voltage of 1.8 V, and after the data transmission has been performed, the MCU controls the second switching circuit  60  to be turned on, and starts to refresh the display content of the electronic ink display screen  40 ; when the refreshing is completed, the MCU may control the first switching sub-circuit  22  to electrically disconnect the supercapacitor C from the energy conversion sub-circuit  21 , namely, automatically disconnecting the charging circuit, so that the supercapacitor C is in a high-resistance loop, which may effectively reduce the self-discharge speed and greatly improve the user experience. 
     In this example, referring to  FIG.  5   , the NFC tag  100  may further include a first capacitor C 1 , a second capacitor C 2 , a third capacitor C 3 , a fourth capacitor C 4  and a fifth capacitor C 5 , wherein capacitance values of the first capacitor Cl and the second capacitor C 2  may be 10 MΩ so as to protect the P-channel MOS transistor; and capacitance values of the third capacitor C 3  and the fourth capacitor C 4  may be 1 K so as to increase the speed of turning on the P-channel MOS transistor. 
     It should be noted that, in this example, the calculation may be made by the following equation: Q=Cv×ΔV=I×t, where Q represents the electric quantity required for refreshing the display content of the electronic ink display screen  40 ; Cv represents a capacitance value of the supercapacitor C, which may be, for example, 0.07 F; ΔV represents a voltage difference, which may be, for example, 1.6 V; I represents a charging current; and t represents a charging period. Furthermore, the electric quantity Q required for refreshing the display content of the electronic ink display screen  40  may be calculated according to the operating current and operating period required for the refreshing, so that when the voltage difference ΔV and the charging current I are known, the capacitance value Cv of the supercapacitor C and the charging period t may be calculated. Thus, charging is performed according to the calculated capacitance value of the supercapacitor and the charging period to improve the charging speed and ensure the efficiency and accuracy of charging. 
     In this example, in the process of data transmission between the NFC tag  100  and the mobile phone  200 , if the transmission is suddenly interrupted, the charging is interrupted, and in this case, it may be ensured that the charging circuit is automatically turned off, thereby reducing the discharge amount of the supercapacitor C, so that if the next charging is performed, the supercapacitor C will continue to be charged on the basis of the electric quantity when the interruption occurs, that is, the electric quantity of the supercapacitor C will not self-discharge to 0 V due to the sudden interruption of the charging, thereby greatly saving the charging period for the second charging. 
     That is, the present disclosure provides an automatically switchable power management circuit that automatically turns on the charging circuit to start wireless charging when the card reader  200  or another mobile terminal providing charging services approaches the NFC tag  200 . When the charging is interrupted, the charging circuit is automatically turned off, thereby reducing the self-discharge of the supercapacitor, effectively ensuring the electric quantity acquired by the supercapacitor, and saving the time period of the next charging. 
     In this example, as shown in  FIG.  6   , when image data transmission between the mobile phone and the NFC tag  100  is performed, at the side of the mobile phone, a user may edit a local image and select the same, and when the mobile phone is close to the NFC tag  100 , the NFC tag  100  may read an ID value of an NFC chip in the mobile phone every 20 seconds to perform verification and establish a connection when the verification passes, and then the mobile phone prompts that the image is ready to be transmitted. Accordingly, the NFC tag  100  continues to perform energy acquisition (wireless charging), and controls to power up the MCU; when the image at the mobile phone starts to be transmitted, accordingly, the NFC tag  100  continues to perform energy acquisition, receives image data; and detect whether the transmission is completed every 6 seconds in the image transmission process. When the transmission is completed, the NFC tag  100  refreshes the display content of the Electronic ink (E-ink) display screen  40  so as to display the image received from the mobile phone, detects whether the refreshing is completed every 16 seconds in the refreshing process, and displays the image on the electronic ink display screen  40  when the refreshing is completed. Thus, the entire communication flow ends. 
     That is, six states of “tag identification”→“connected”→“wireless charging”→“image data transmission”→“E-ink refreshing”→“disconnected” may be realized in sequence by the two sides of the mobile phone and the NFC tag through a negotiation of the states. Thus, the automatic management of charging and data transmission states is realized, and the adverse effects caused by many uncertain states (for example, the card reader being not in the field, a tag being not identified) in the NFC process are suppressed. 
     It should be noted that the embodiments of the present disclosure do not use a battery, and thus the power supply voltage of the NFC tag  100  may be updated in real time to determine the next step to be performed, which increases the success rate of tag refreshing. 
     Therefore, in the NFC tag according to the embodiments of the present disclosure, the energy storage circuit is charged under the action of a magnetic field signal to realize wireless charging, which does not require the battery power supply, and is more energy-saving and environmentally-friendly, has the advantages of low cost and low power consumption, and satisfies the user&#39;s battery free requirement. The technologies of wireless charging, NFC, energy acquisition, energy storage and ink refreshing are combined, and reasonable utilization of electric quantity are realized through intensive electric quantity management, so that the NFC tag is more energy-saving and environmental-friendly. The charging circuit is controlled to be automatically turned on and automatically turned off, so that next longer charging period due to self-discharge is avoided, and the next charging period is saved. Moreover, it implements high degree of automation, and greatly improves the user experience. 
       FIG.  7    is a structural block diagram of a control system for a NFC tag according to an embodiment of the present disclosure. 
     As shown in  FIG.  7   , the system  1000  includes a card reader  200  and the NFC tag  100  according to the above embodiments of the present disclosure. The card reader  200  may be a mobile terminal having a NFC function. 
     The control system for the NFC tag uses the NFC tag according to the embodiments of the present disclosure, an energy storage circuit thereof is charged under the action of a magnetic field signal to realize wireless charging, which does not require the battery power supply, so that the system is more energy-saving and environmentally friendly, and has advantages of low cost and low power consumption. 
     In the description of the present disclosure, it should be understood that the orientation or positional relationship indicated by the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “anticlockwise”, “axial”, “radial”, “circumferential”, and the like is based on the orientation or positional relationship shown in the drawings, and is merely for convenience of describing the present disclosure and simplifying the description, but not indicate or imply that the referred device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present disclosure. 
     In addition, the terms “first” and “second” are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined with “first”, “second” may explicitly or implicitly include one or more of such features. In the description of the present disclosure, the meaning of “a plurality” is at least two, for example, two, three, etc. unless and specifically limited otherwise. 
     In the description of the present disclosure, it should be noted that the terms “mount”, “connect”, “connected”, “fix”, and the like are to be construed broadly, for example, may be fixedly connected, removably connected, or integrally connected, may be a mechanical connection or an electric connection, may be a direct connection or an indirect connection through an intermediate medium, may be a communication or an interaction between two elements, unless explicitly stated or defined. The specific meanings of the above terms in the present disclosure will be understood on a case-by-case basis by those of ordinary skill in the art. 
     In the present disclosure, a first feature is “above” or “below” a second feature, which means that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Further, the first feature is “on”, “above” and “over” the second feature, which may be that the first feature is directly above or obliquely above the second feature, or merely indicate that the first feature is at a higher level than the second feature. The first feature is “under”, “below” and “beneath” the second feature, which may be that the first feature is directly below or obliquely below the second feature, or merely indicate that the first feature is at a lower level than the second feature. 
     In the description of the present specification, the reference terms “an embodiment”, “some embodiments”, “examples”, “specific examples”, “some examples”, and like mean that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In the present specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art can integrate and combine different embodiments or examples as well as features of different embodiments or examples described in the present specification without contradicting each other. 
     While the embodiments of the present disclosure are illustrated and described above, it should be understood that the above embodiments are illustrative and not restrictive to the present disclosure, and those skilled in the art can make changes, modifications, substitutions, and variations to the embodiments within the scope of the present disclosure.