NFC (Near Field Communication) passive tag identification system, NFC passive tag identification method and NFC equipment

Abstract

One or more embodiments of the present specification relate to an NFC passive tag identification system, method, and NFC device. The system includes an energy harvesting circuit for harvesting and storing environmental energy. The system also comprises a radio frequency transmitting circuit which is connected with the energy collection circuit, is powered by the environment energy, and is used for transmitting an excitation signal for enabling the terminal equipment to quit the low power consumption card detection LPCD mode. In addition, the system also comprises an NFC label circuit which is used for sensing an NFC detection signal sent by the terminal equipment so as to communicate with the terminal equipment.

Description

Technical Field

[0001] The embodiments of the present specification generally relate to the field of near field communication (NFC) technology, and more specifically to an NFC passive tag recognition system, method and NFC device. Background Art

[0002] NFC, or Near Field Communication, is a short-range, high-frequency radio technology that evolved from contactless Radio Frequency Identification (RFID) technology. It supports short-range wireless communication between mobile devices, consumer electronics, PCs, and smart control tools. Its operating frequency is 13.56MHz, and the transmission distance is within 10cm or 20cm. NFC is a wireless connection technology that provides easy, secure, and fast communication, with the characteristics of short distance, high bandwidth, and low energy consumption.

[0003] NFC devices can be divided into passive NFC devices and active NFC devices. Passive NFC devices include NFC tags and other small transmitters, which can send information to other NFC devices without the need for power, so they have the advantages of low cost, long service life and strong environmental adaptability; active NFC devices can send and receive data, and can communicate with each other and with passive devices. Active NFC devices can only work when powered. Summary of the invention

[0004] In view of this, one or more embodiments of the present specification provide an NFC passive tag recognition system, method and NFC device, which can collect and store various environmental energies for sending carrier signals of NFC radio frequency fields, so that nearby terminal devices such as NFC card readers exit LPCD mode and communicate in normal card detection mode, thereby improving NFC tag recognition efficiency in a passive NFC scenario in a low-power and low-cost manner.

[0005] In the first aspect of the present specification, a NFC passive tag identification system is provided. The system includes an energy collection circuit for collecting and storing environmental energy. The system also includes a radio frequency transmission circuit connected to the energy collection circuit, powered by the environmental energy, and used to send an excitation signal for causing a terminal device to exit a low power consumption card detection LPCD mode. In addition, the system also includes an NFC tag circuit for sensing an NFC detection signal sent by the terminal device to communicate with the terminal device.

[0006] In a second aspect of the present specification, a method for identifying an NFC passive tag is provided. The method includes collecting and storing environmental energy. The method also includes sending an excitation signal for causing a terminal device to exit a low power consumption card detection LPCD mode based on the environmental energy. In addition, the method also includes sensing an NFC detection signal sent by the terminal device to communicate with the terminal device.

[0007] In a third aspect of the present specification, an NFC device is provided. The NFC device operates in a passive mode, and a terminal device communicating with the NFC device operates in an active mode. The NFC device includes the system according to the first aspect of the present specification.

[0008] It should be understood that the contents described in the Summary of the Invention are not intended to limit the key or important features of the embodiments of this specification, nor are they intended to limit the scope of this disclosure. Other features of this specification will become easy to understand through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other purposes, features and advantages of the various embodiments of the present specification will become more easily understood through the following detailed description with reference to the accompanying drawings. In the accompanying drawings, various embodiments of the present specification will be described in an exemplary and non-limiting manner, wherein:

[0010] Figure 1 A schematic diagram of the structure of an NFC passive tag recognition system according to some embodiments of this specification is shown;

[0011] Figure 2 A schematic diagram of a circuit layout of an NFC passive tag identification system according to some embodiments of this specification is shown;

[0012] Figure 3A A schematic diagram of the structure of a radio frequency transmitting circuit according to some embodiments of this specification is shown;

[0013] Figure 3B An equivalent circuit diagram of a radio frequency transmitting circuit according to some embodiments of the present specification is shown;

[0014] Figure 4A A schematic diagram of the structure of an NFC tag circuit according to some embodiments of this specification is shown;

[0015] Figure 4B An equivalent circuit diagram of an NFC tag circuit according to some embodiments of the present specification is shown; and

[0016] Figure 5 A flowchart of an NFC passive tag identification method according to some embodiments of the present specification is shown.

[0017] Throughout the drawings, the same or similar reference numbers refer to the same or similar elements. DETAILED DESCRIPTION

[0018] The embodiments of the present specification will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present specification are shown in the accompanying drawings, it should be understood that the present specification can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present specification. It should be understood that the drawings and embodiments of the present specification are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0019] In the description of the embodiments of this specification, the term "including" and similar terms should be understood as open inclusion, that is, "including but not limited to". The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0020] As mentioned above, NFC has been sought after by more and more industries in recent years due to its characteristics of short distance, fast connection, low power consumption, and high compatibility. It has been widely used in scenarios such as mobile payment, data exchange, and access control. Among them, the passive NFC tag is a near-field communication device that does not rely on its own power supply. This tag exchanges data with the NFC reader through a short-range wireless signal. When the NFC reader is close to the passive tag, the electromagnetic field emitted by the reader powers the tag, and the tag's built-in circuit starts working. The tag then transmits the stored data back to the reader through modulation to complete the data interaction.

[0021] Low Power Card Detection (LPCD) mode is a low-power card detection method that allows the NFC reader to detect the proximity of a card without the need for continuous polling. This mode is implemented by periodically sending radio frequency (RF) pulses and monitoring the reflected signal. When a signal change (such as detuning) is detected, it triggers the NFC reader to further communicate.

[0022] When performing NFC tag recognition, terminal devices with NFC card reading functions are usually in active mode, and monitor whether there is an NFC device approaching by emitting an electric field. However, since terminal devices, especially mobile devices, are usually battery-powered, in order to extend battery life and improve battery life, some terminal devices will automatically switch to LPCD mode within a period of time after the screen is turned on. Once in LPCD mode, if the coupling area of ​​the antenna is insufficient or the electric field change is not significant enough, the terminal device may find it difficult to exit this mode, resulting in the normal communication between the terminal device and the NFC tag being blocked, which in turn affects the NFC recognition success rate and the user experience.

[0023] To this end, an NFC passive tag recognition system is provided in the embodiments of this specification. The system can collect and store various environmental energies for sending carrier signals of NFC radio frequency fields, so that the terminal devices such as NFC card readers approaching can exit the LPCD mode and communicate with the NFC tag in the normal card detection mode, thereby improving the NFC recognition efficiency in a low-cost and low-power manner in the passive NFC scenario.

[0024] Figure 1 FIG. 1 shows a schematic diagram of the structure of an NFC passive tag recognition system 100 according to some embodiments of this specification. Figure 1 As shown, the NFC passive tag identification system 100 may include an energy harvesting circuit 102 , a radio frequency transmission circuit 104 and an NFC tag circuit 106 .

[0025] The energy harvesting circuit 102 can collect and store ambient energy from the surrounding environment to provide energy to the RF transmission circuit 104. Environmental energy harvesting technology (Energy Harvesting, EH) refers to the collection and use of available energy from the environment to supply power or charging equipment. Environmental energy includes but is not limited to wireless radio frequency energy, thermal energy, light energy, etc. These energy sources have the characteristics of universality, stability and continuity, and therefore can serve as a reliable source of energy harvesting.

[0026] In some embodiments, a radio frequency energy harvesting circuit can be used to capture energy from a radio frequency signal and convert it into electrical energy. Specifically, an antenna can be used to first capture electromagnetic waves (radio frequency signals) and convert them into electrical signals. Then, the alternating current (AC) signal captured by the antenna is converted into a direct current (DC) signal by a rectifier. Optionally, the rectifier can be implemented using devices such as diodes or metal-oxide semiconductor field effect transistors (MOSFETs).

[0027] In some embodiments, a thermal energy harvesting circuit can also be used to capture thermal energy from the environment and convert it into electrical energy. Specifically, a thermopile composed of multiple thermocouples connected in series can be used, and an electromotive force will be generated when a temperature difference is generated at both ends. Alternatively, the characteristic of pyroelectric elements that generate electric charge when the temperature changes can also be used to convert the captured thermal energy into electrical energy.

[0028] In some embodiments, a photovoltaic energy collection circuit can also be used to convert light energy into electrical energy using the photovoltaic effect. Specifically, photons can be used to excite electrons in a photovoltaic cell, thereby generating current.

[0029] Since the collected ambient energy is usually weak and unstable, energy storage elements are needed to store and manage this energy. For example, capacitors or lithium-ion batteries can be used to store the electrical energy converted from ambient energy.

[0030] In some embodiments, the energy collection circuit 102 may also be connected to a boost voltage regulator circuit and an oscillation circuit. The boost voltage regulator circuit can be used to increase the output voltage to meet the voltage requirement of the RF transmission circuit 104. The oscillation circuit can be used to generate a periodic voltage signal and send it to the RF transmission circuit 104, so that the RF transmission circuit 104 periodically sends an excitation signal. Specifically, the ambient energy collected by the energy collection circuit 102 can first be converted into a smooth and stable DC voltage via a boost voltage regulator circuit, and then converted into an AC oscillation signal of a specific frequency via an oscillation circuit, and sent to the RF transmission circuit 104.

[0031] The RF transmission circuit 104 can transmit an excitation signal for causing the terminal device to exit the low power consumption card detection LPCD mode based on the energy provided by the energy collection circuit 102. The energy provided by the energy collection circuit 102 can be the periodic voltage signal generated by the oscillation circuit.

[0032] The above-mentioned terminal devices with NFC card reading function, including but not limited to mobile terminal devices of the smartphone type, smart watches, smart glasses and other smart wearable devices, are usually powered by batteries and are very sensitive to power consumption. In order to control power consumption, they usually make many low-power designs for the transmission power of their own card readers, including setting LPCD mode. For example, most smartphones will automatically switch to LPCD mode within a period of time after the screen is turned on.

[0033] In actual applications, only when the terminal device detects that the RF signal it transmits is sensed by the nearby NFC target device, and the signal strength change caused by this induction reaches or exceeds the preset threshold, the mobile device will wake up from the LPCD mode and enter the normal card reading mode. However, in the LPCD mode, the signal strength emitted by the terminal device is weakened, and the amplitude of the RF signal will be lower than that in the normal card reading mode. This causes the NFC target device to respond to the signal with a corresponding decrease, making it difficult for the terminal device to accurately determine whether there is an NFC target device around based on the change in signal amplitude. Therefore, the terminal device can be stimulated to exit the LPCD mode by actively transmitting a high-intensity excitation signal.

[0034] In some embodiments, the radio frequency transmission circuit 104 may include a first NFC chip connected to the energy collection circuit 102 and an excitation coil connected to the first NFC chip. The first NFC chip can receive the AC oscillation signal generated by the energy collection circuit 102 as described above, modulate it to a carrier signal (i.e., an excitation signal) of a radio frequency field containing a specified data packet (including but not limited to commands such as card search and P2P transmission), and send it to the excitation coil. Then, the excitation coil can send the excitation signal to form an radio frequency field around the system. Optionally, the excitation signal can also be an empty carrier signal that does not contain any information to reduce the system burden of the transmission signal. The first NFC chip can be any NFC chip that supports the 13.56MHz carrier standard. The above-mentioned first NFC chip and excitation coil can be provided by commercial chips that can be purchased, and this specification does not limit this.

[0035] The NFC tag circuit 106 can sense the NFC detection signal sent by the terminal device to communicate with the terminal device. The NFC tag circuit 106 may include a second NFC chip and an NFC coil. Specifically, the NFC detection signal from the terminal device can be received by the NFC coil, and an electromagnetic induction current can be generated at the same time for the second NFC chip to receive and send data. Similarly, since the communication carrier frequency 13.56MHz of NFC technology has been standardized worldwide, the second NFC chip can be any NFC chip that supports the 13.56MHz carrier standard. The above-mentioned second NFC chip and NFC coil can be provided by commercial chips that can be purchased, and this specification does not limit this.

[0036] In different scenarios, the second NFC chip can contain different information. For example, in a payment scenario, the second NFC chip can contain payment order information. For example, in a food ordering scenario, the second NFC chip can contain menu and seat information. For another example, in a door access control scenario, the second NFC chip can contain identity verification information.

[0037] It should be understood that the architecture and functions in the system 100 are described for exemplary purposes only, and do not imply any limitation on the scope of the present description. The embodiments of the present description may also be applied to other environments with different structures and / or functions.

[0038] The following will combine Figures 2 to 5 The process according to the embodiment of this specification is described in detail. For ease of understanding, the specific data mentioned in the following description are exemplary and are not intended to limit the scope of protection of the present disclosure. It should be understood that the embodiments described below may also include additional actions not shown and / or may omit the actions shown, and the scope of the present disclosure is not limited in this respect.

[0039] Since the system involves two NFC coil circuits, in which the RF transmission circuit 104 transmits a carrier signal of the RF field through external power supply to make the terminal device exit the LPCD mode, and the NFC tag circuit 106 generates electricity by itself, stores information and responds to the NFC detection signal of the terminal device, when laying out the circuit, interference should be avoided when the terminal device receives the excitation signal and reads the data stored in the NFC tag circuit.

[0040] Figure 2 FIG. 2 shows a schematic diagram of the structure of an NFC passive tag recognition system 200 according to some embodiments of this specification. Figure 2 As shown, the RF transmission circuit 104 and the NFC tag circuit 106 can be overlapped and arranged in the same plane, and the RF transmission circuit 104 can include a first NFC chip 204 and an excitation coil 206, and the excitation coil 206 can be arranged on the outermost side. The first NFC chip 204 can be powered by the energy collection circuit 202 through the positive voltage supply terminal VDD and the ground terminal VSS. The NFC tag circuit 106 may include a second NFC chip 208 and an NFC coil 210. The NFC tag circuit 106 is located on the inner side of the excitation coil 206. In this way, signal interference can be avoided as much as possible.

[0041] In some embodiments, the RF transmission circuit 104 and the NFC tag circuit 106 may be arranged vertically or horizontally, etc. This specification does not limit the specific circuit layout.

[0042] Figure 3A FIG. 2 shows a schematic diagram of the structure of a radio frequency transmission circuit 300 according to some embodiments of the present specification. Figure 3AAs shown, the RF transmission circuit 300 may include a first NFC chip 302, a first low-pass filter 304, a first matching circuit 306, a first current limiting element 308 and an excitation coil 310. The energy collection circuit 202 may supply power to the first NFC chip 302 through the positive voltage supply terminal VDD and the ground terminal VSS, for example, to provide a periodic AC oscillation signal. The first low-pass filter 304 may include an inductor and a capacitor, and utilizes its characteristic of only allowing signals below the cutoff frequency to pass, while signals above the cutoff frequency cannot pass, to filter out the higher harmonics of the crystal oscillator, thereby improving the stability of signal transmission.

[0043] The first matching circuit 306 can be tuned with the excitation coil 310 to adjust the impedance parameters and the resonant frequency parameters. The first current limiting element 308 can include a series resistor, which can adjust the balance between the quality factor (which can be called the Q value) of the excitation coil 310 and the bandwidth of the circuit. The Q value reflects the loss of the coil at the resonant frequency and is inversely proportional to the circuit bandwidth. The excitation coil 310 can send an excitation signal for exciting the terminal device to exit the LPCD mode.

[0044] Figure 3B FIG. 2 shows an equivalent circuit diagram of a radio frequency transmission circuit according to some embodiments of the present specification. Figure 3B As shown, the first NFC chip 302 can be expressed as a chip IC1 for signal modulation and demodulation and data reception and transmission. The oscillating AC signal of the energy collection circuit 202 flows in from the positive power supply VDD, flows out from the ground VSS after passing through the components, and forms a loop. The chip IC1 may include multiple pins, such as a pin Rx for receiving external data, a transient voltage suppressor Tvss to ground for preventing the circuit from being damaged by transient overvoltage (such as lightning strike, electrostatic discharge, etc.), and differential signal transmission pins Tx+ and Tx- for high-speed, interference-resistant data transmission.

[0045] like Figure 3B As shown, the first low-pass filter 304 can be composed of an inductor L0 and a capacitor C0 to filter out the high-order harmonics of the crystal oscillator. The capacitor C1 and the capacitor C2 can form a first matching circuit 306 to adjust the impedance parameters and the resonant frequency parameters. The resistor R1 can be used as a first current limiting element 308 to adjust the Q value of the coil ANT1, that is, the excitation coil 310 and the bandwidth of the circuit.

[0046] Figure 4A FIG. 4 shows a schematic diagram of the structure of an NFC tag circuit 400 according to some embodiments of this specification. Figure 4AAs shown, the NFC tag circuit 400 may include a second NFC chip 402, a second low-pass filter 404, a second matching circuit 406, a second current limiting element 408, and an NFC coil 410. Similar to the RF transmission circuit 300, the second low-pass filter 404 may include an inductor and a capacitor, and utilizes its characteristics of only allowing signals below the cutoff frequency to pass, while signals above the cutoff frequency cannot pass, to filter out the high harmonics of the crystal oscillator, thereby improving the stability of signal transmission. The second current limiting element 408 may include a series resistor, which can adjust the balance between the quality factor (which may be called the Q value) of the NFC coil 410 and the bandwidth of the circuit.

[0047] The second matching circuit 406 can be tuned with the NFC coil 410 and send the matched signal to the second NFC chip 402. Then, the second NFC chip 402 can modulate the matched signal into a carrier signal and send it to the NFC coil 410. The NFC coil can sense the NFC detection signal sent by the terminal device and send the above carrier signal.

[0048] Figure 4B FIG. 2 shows an equivalent circuit diagram of an NFC tag circuit according to some embodiments of the present specification. Figure 4B As shown, the second NFC chip 402 may be a chip IC2 for signal modulation and demodulation and data reception and transmission, and specific information is stored therein, including but not limited to ordering information, payment information, etc. Similarly, the chip IC2 may include a plurality of pins, such as a pin Rx for receiving external data, a transient voltage suppressor Tvss to ground for preventing the circuit from being damaged by transient overvoltage (such as lightning strike, electrostatic discharge, etc.), and differential signal transmission pins Tx+ and Tx- for high-speed, interference-resistant data transmission.

[0049] like Figure 3B As shown, the second low-pass filter 404 can be composed of an inductor L0 and a capacitor C0 to filter out the high harmonics of the crystal oscillator. Capacitors C1 and C2 can form a second matching circuit 406 to adjust impedance parameters and resonant frequency parameters. Resistor R1 can be used as a second current limiting element 408 to adjust the Q value of coil ANT2, that is, NFC coil 410 and the bandwidth of the circuit. This circuit relies on the electromagnetic induction current of coil ANT2 when the terminal device is close, without the need for an external power supply.

[0050] Figure 5 The flowchart of the NFC passive tag identification method according to some embodiments of the present specification is shown. It should be understood that the method 500 may also include additional actions not shown and / or may omit the actions shown, and the scope of the present disclosure is not limited in this respect.

[0051] like Figure 5As shown, at block 510, method 500 may include: collecting and storing ambient energy. Ambient energy may include, but is not limited to, wireless radio frequency energy, thermal energy, light energy, etc. that are universal, stable, and continuous, and the acquisition method may include a corresponding energy collection circuit. Then, a capacitor or a lithium-ion battery may be used to store and manage the electrical energy converted from the ambient energy.

[0052] In block 520, method 500 may include: based on the environmental energy, sending an excitation signal for causing the terminal device to exit the low power consumption card detection LPCD mode. In some embodiments, the carrier signal of the NFC chip transmitting the radio frequency field may be periodically called, and when the terminal device in the low power consumption card detection LPCD mode approaches the radio frequency field, it will switch from the LPCD mode to the normal card reading mode based on the radio frequency signal. In this way, it is possible to improve the NFC card reading efficiency in a low-cost and low-consumption manner in the NFC passive tag scenario.

[0053] In block 530, method 500 may include: sensing an NFC detection signal sent by the terminal device to communicate with the terminal device. Through the effect of the radio frequency field, the NFC tag circuit carrying specific information can interact with the terminal device in normal card reading mode, thereby achieving efficient communication.

[0054] In addition, the embodiments of this specification also provide an NFC device corresponding to the NFC passive tag recognition system, and the NFC device may include any one of the NFC passive tag recognition systems provided in the above embodiments.

[0055] Specifically, the NFC device may include an NFC passive tag identification system, and the system may include an energy collection circuit 102, a radio frequency transmission circuit 104, and an NFC tag circuit 106. The energy collection circuit 102 may be used to collect and store environmental energy; the radio frequency transmission circuit 104 is connected to the energy collection circuit 102, powered by environmental energy, and may be used to send an excitation signal for causing the terminal device to exit the low power consumption card detection LPCD mode; the NFC tag circuit 106 may be used to sense the NFC detection signal sent by the terminal device to communicate with the terminal device.

[0056] In some embodiments, the energy harvesting circuit 102 may include at least one of: a radio frequency energy harvesting circuit; a thermal energy harvesting circuit; and a photovoltaic energy harvesting circuit.

[0057] In some embodiments, the system may further include a boost voltage regulator circuit connected to the energy collection circuit 102 for increasing the output voltage of the energy collection circuit 102 ; and an oscillation circuit connected to the boost voltage regulator circuit and the RF transmission circuit 104 for generating a periodic voltage signal and sending it to the RF transmission circuit 104 .

[0058] In some embodiments, the RF transmission circuit 104 may include a first NFC chip, connected to the energy collection circuit, powered by the energy collection circuit, and used to send an excitation signal; an excitation coil, connected to the first NFC chip, used to receive the excitation signal from the first NFC chip and send it; and a first matching circuit, connected to the first NFC chip and the excitation coil, used to adjust the impedance parameters and the resonant frequency parameters of the excitation coil.

[0059] In some embodiments, the RF transmission circuit 104 may further include a first filtering circuit connected to the first NFC chip for filtering out interference signals in the RF transmission circuit; and a first current limiting element connected to the excitation coil for adjusting the quality factor of the excitation coil and the bandwidth of the RF transmission circuit.

[0060] In some embodiments, the first filtering circuit may include a first low-pass filter, and the interference signal may include a high-order harmonic of a crystal oscillator.

[0061] In some embodiments, the energy collection circuit 102 , the radio frequency transmission circuit 104 , and the NFC tag circuit 106 may be located in the same plane, and the energy collection circuit 102 , the first NFC chip, and the NFC tag circuit 106 are all located inside the excitation coil.

[0062] In some embodiments, the NFC tag circuit 106 may include an NFC coil, which is used to sense an NFC detection signal sent by a terminal device and generate an induced current; a second NFC chip, which is connected to the NFC coil and powered by the induced current, and is used to send a carrier signal carrying target data to the NFC coil to communicate with the terminal device; and a first matching circuit, which is connected to the second NFC chip and the NFC coil, and is used to adjust the impedance parameters and the resonant frequency parameters of the NFC coil.

[0063] In some embodiments, the NFC tag circuit 106 may further include a second filtering circuit connected to the second NFC chip for filtering out interference signals in the NFC tag circuit; and a second current limiting element connected to the NFC coil for adjusting the quality factor of the NFC coil and the bandwidth of the NFC tag circuit.

[0064] In some embodiments, the second filtering circuit may include a second low-pass filter, and the interference signal may include a higher harmonic of the crystal oscillator.

[0065] In addition, the shell of the NFC device can include but is not limited to various non-metallic objects such as PVC, acrylic, wood, etc. to avoid signal interference.

[0066] In the embodiments of this specification, the NFC device operates in a passive mode, and the terminal device communicating with the NFC device operates in an active mode.

[0067] In the embodiments of this specification, the NFC device operating in the passive mode can not only passively complete communication, but also actively stimulate the terminal device to communicate in the normal working mode.

[0068] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0069] The embodiments of the present specification have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

[0070] The above are only optional embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An NFC passive tag recognition system, comprising: Energy harvesting circuit for collecting and storing ambient energy; A radio frequency transmission circuit, connected to the energy collection circuit, powered by the ambient energy, and used to send an excitation signal for causing the terminal device to exit the low power consumption card detection LPCD mode; as well as The NFC tag circuit is used to sense the NFC detection signal sent by the terminal device to communicate with the terminal device.

2. The system of claim 1, wherein the energy harvesting circuit comprises at least one of: RF energy harvesting circuit; Thermal energy harvesting circuits; and Photovoltaic energy harvesting circuit.

3. The system according to claim 1, wherein the system further comprises: A boost and voltage stabilization circuit, connected to the energy collection circuit, and used to increase the output voltage of the energy collection circuit; as well as The oscillation circuit is connected to the boost and voltage stabilization circuit and the radio frequency transmission circuit, and is used for generating a periodic voltage signal and sending the signal to the radio frequency transmission circuit.

4. The system according to claim 1, wherein the radio frequency transmission circuit comprises: A first NFC chip is connected to the energy collection circuit, powered by the energy collection circuit, and used to send the excitation signal; an excitation coil, connected to the first NFC chip, and configured to receive and send the excitation signal from the first NFC chip; as well as The first matching circuit is connected to the first NFC chip and the excitation coil, and is used to adjust the impedance parameter and the resonant frequency parameter of the excitation coil.

5. The system according to claim 4, wherein the radio frequency transmission circuit further comprises: A first filtering circuit, connected to the first NFC chip, and configured to filter out interference signals in the radio frequency transmission circuit, wherein the first filtering circuit comprises a first low-pass filter, and the interference signals comprise higher harmonics of a crystal oscillator; as well as The first current limiting element is connected to the excitation coil and is used to adjust the quality factor of the excitation coil and the bandwidth of the radio frequency transmission circuit.

6. The system according to claim 4, wherein the energy collection circuit, the radio frequency transmission circuit and the NFC tag circuit are located in the same plane, and the energy collection circuit, the first NFC chip and the NFC tag circuit are all located inside the excitation coil.

7. The system of claim 1, wherein the NFC tag circuit comprises: An NFC coil, used to sense an NFC detection signal sent by the terminal device and generate an induced current; a second NFC chip, connected to the NFC coil, powered by the induced current, and used to send a carrier signal carrying target data to the NFC coil to communicate with the terminal device; as well as The first matching circuit is connected to the second NFC chip and the NFC coil, and is used to adjust an impedance parameter and a resonant frequency parameter of the NFC coil.

8. The system of claim 7, wherein the NFC tag circuit further comprises: A second filtering circuit, connected to the second NFC chip, for filtering out interference signals in the NFC tag circuit, wherein the second filtering circuit comprises a second low-pass filter, and the interference signals comprise higher harmonics of a crystal oscillator; as well as The second current limiting element is connected to the NFC coil and is used to adjust the quality factor of the NFC coil and the bandwidth of the NFC tag circuit.

9. A method for identifying an NFC passive tag, comprising: harvesting and storing ambient energy; Based on the environmental energy, sending an excitation signal for causing the terminal device to exit a low power consumption card detection LPCD mode; as well as The NFC detection signal sent by the terminal device is sensed to communicate with the terminal device.

10. An NFC device, wherein the NFC device operates in a passive mode, and a terminal device communicating with the NFC device operates in an active mode, wherein the NFC device comprises the NFC passive tag recognition system according to any one of claims 1 to 8.

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