NFC passive tag identification and NFC device

Abstract

The present application relates to an NFC passive tag identification system and method, and an NFC device. The system comprises an energy harvesting circuit, used for harvesting and storing electric energy converted from mechanical energy which is generated by a terminal device touching the system. The system further comprises a radio frequency transmitting circuit, which is connected to the energy harvesting circuit, is powered by the energy harvesting circuit, and is used for transmitting an excitation signal enabling the terminal device to exit a low power card detection (LPCD) mode. In addition, the system further comprises an NFC tag circuit, used for sensing an NFC detection signal transmitted by the terminal device so as to communicate with the terminal device.

Description

NFC passive tag identification and NFC devices Technical Field

[0001] The embodiments in this specification generally relate to the field of Near Field Communication (NFC) technology, and more specifically to an NFC passive tag identification system, method and NFC device. Background Technology

[0002] NFC, or Near Field Communication, is a short-range, high-frequency wireless technology evolved from contactless Radio Frequency Identification (RFID). It supports short-range wireless communication between mobile devices, consumer electronics, PCs, and smart control tools. It operates at a frequency of 13.56 MHz and has a transmission distance of 10 to 20 centimeters. As a wireless connectivity technology that provides easy, secure, and fast communication, NFC features short range, high bandwidth, and low power 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. They can send information to other NFC devices without requiring a power source, thus offering advantages such as low cost, long lifespan, and strong environmental adaptability. Active NFC devices can send and receive data and can communicate with each other as well as with passive devices. Active NFC devices can only operate when powered. Summary of the Invention

[0004] In view of this, one or more embodiments of this specification provide an NFC passive tag identification system, method, and NFC device that can convert the mechanical energy generated when a terminal device collides with the system into electrical energy to transmit carrier signals of the NFC radio frequency field, causing nearby NFC card readers and other terminal devices to exit LPCD mode and communicate in normal card detection mode, thereby improving NFC tag identification efficiency in passive NFC scenarios with low power consumption and low cost.

[0005] In a first aspect of this specification, an NFC passive tag identification system is provided. The system includes an energy harvesting circuit for harvesting and storing electrical energy converted from the mechanical energy generated by contact between a terminal device and the system. The system also includes a radio frequency transmission circuit connected to and powered by the energy harvesting circuit for transmitting an excitation signal to cause the terminal device to exit the low-power card detection (LPCD) mode. Furthermore, the system includes an NFC tag circuit for sensing NFC detection signals transmitted by the terminal device to communicate with the terminal device.

[0006] In a second aspect of this specification, an NFC passive tag identification method is provided. The method includes collecting and storing electrical energy converted from mechanical energy generated by a collision. The method also includes sending an excitation signal, based on the electrical energy converted from the mechanical energy generated by the collision, to cause a terminal device to exit a low-power card detection (LPCD) mode. Furthermore, the method includes sensing an NFC probe signal sent by the terminal device to communicate with the terminal device.

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

[0008] It should be understood that the description in the Summary of the Invention section is not intended to limit the key or essential features of the embodiments of this specification, nor is it intended to limit the scope of this disclosure. Other features of this specification will become readily apparent from the following description. Attached Figure Description

[0009] The above and other objects, features, and advantages of the embodiments of this specification will become more readily understood from the following detailed description with reference to the accompanying drawings. Several embodiments of this specification will be described by way of example and non-limitation in the drawings.

[0010] Figure 1 shows a schematic diagram of the structure of an NFC passive tag identification system according to some embodiments of this specification.

[0011] Figure 2 shows a schematic diagram of the stacked structure of an NFC passive tag identification system according to some embodiments of this specification.

[0012] Figure 3 shows a schematic circuit layout of an NFC passive tag identification system according to some embodiments of this specification.

[0013] Figure 4A shows a schematic diagram of the structure of a radio frequency transmission circuit according to some embodiments of this specification.

[0014] Figure 4B shows an equivalent circuit diagram of a radio frequency transmission circuit according to some embodiments of this specification.

[0015] Figure 5A shows a schematic diagram of the structure of an NFC tag circuit according to some embodiments of this specification.

[0016] Figure 5B shows an equivalent circuit diagram of an NFC tag circuit according to some embodiments of this specification.

[0017] Figure 6 shows a flowchart of an NFC passive tag identification method according to some embodiments of this specification.

[0018] In all the accompanying figures, the same or similar reference numerals denote the same or similar elements. Detailed Implementation

[0019] Embodiments of this specification will now be described in more detail with reference to the accompanying drawings. While some embodiments of this specification are shown in the drawings, it should be understood that this specification can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this specification. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0020] In the description of embodiments in this specification, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based 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.

[0021] As mentioned above, NFC has gained increasing popularity across various industries in recent years due to its short-range, fast connection, low power consumption, and high compatibility, finding wide application in scenarios such as mobile payment, data exchange, and access control. Passive NFC tags are near-field communication devices that do not rely on their own power source. These tags exchange data via short-range wireless signals with NFC readers. When an NFC reader approaches a passive tag, the electromagnetic field emitted by the reader powers the tag, activating its built-in circuitry. The tag then transmits its stored data back to the reader via modulation, completing the data exchange.

[0022] Low Power Card Detection (LPCD) mode is a low-power card detection method that allows NFC readers to detect card proximity without continuous polling. This mode achieves this by periodically sending radio frequency (RF) pulses and monitoring reflected signals. When a signal change (such as detuning) is detected, it triggers the NFC reader to initiate further communication.

[0023] When identifying NFC tags, terminal devices with NFC card reading capabilities are typically in active mode, detecting the presence of nearby NFC devices by emitting an electric field. However, since terminal devices, especially mobile devices, are usually battery-powered, some devices automatically switch to LPCD mode after the screen is on for a period of time to extend battery life and improve battery performance. Once in LPCD mode, if the antenna coupling area is insufficient or the electric field change is not significant enough, the terminal device may have difficulty exiting this mode, thus hindering normal communication between the terminal device and the NFC tag, affecting the NFC identification success rate, and impacting the user experience.

[0024] Therefore, this specification provides an NFC passive tag identification system in its embodiments. This system can convert the mechanical energy generated when a terminal device collides with the system into electrical energy to transmit carrier signals for the NFC radio frequency field. This causes nearby NFC readers and other terminal devices to exit LPCD mode and communicate with the NFC tag in normal card detection mode, thereby improving NFC identification efficiency in passive NFC scenarios with low cost and low power consumption.

[0025] Figure 1 shows a schematic diagram of the structure of an NFC passive tag identification system 100 according to some embodiments of this specification. As shown in Figure 1, the NFC passive tag identification system 100 may include an energy harvesting circuit 102, an radio frequency transmission circuit 104, and an NFC tag circuit 106. The energy harvesting circuit 102 can convert the mechanical energy generated by the collision between the terminal device and the system into electrical energy. Methods for converting mechanical energy into electrical energy include, but are not limited to, utilizing the piezoelectric effect, the principle of magnetic induction, electrostatic induction, and mechanical kinetic energy switches.

[0026] The piezoelectric effect is a physical phenomenon that refers to the generation of electric charge or voltage in certain materials (which may be called piezoelectric materials) when subjected to mechanical stress (such as tension, compression, or bending), and vice versa. When an electric field is applied to these materials, they will deform. In some embodiments, the energy harvesting circuit 102 may utilize the piezoelectric effect to convert the mechanical energy generated when the terminal device collides with the system 100 into electrical energy to provide power to the radio frequency transmitting circuit 104.

[0027] Alternatively, piezoelectric materials can be piezoelectric sheets, which have a simple structure, low cost, and are easy to integrate. Alternatively, piezoelectric materials can also be piezoelectric ceramics, piezoelectric crystals, piezoelectric thin films, etc., to meet specific application requirements. For example, the high flexibility of piezoelectric thin films can be utilized in applications with complex surface shapes.

[0028] When a conductor in a closed circuit moves through a magnetic field, cutting magnetic field lines, an induced current is generated in the conductor. This phenomenon is called electromagnetic induction. Mechanical energy generated by contact (such as pressing or touching) can be converted into the conductor's kinetic energy or deformation energy, which in turn drives the conductor to move in the magnetic field, generating an induced current.

[0029] For example, a combination of a spring and an induction coil can be used to convert mechanical energy into electrical energy. Specifically, as the component that receives and converts mechanical energy, the spring deforms when touched, thus converting mechanical energy into deformation energy. When the spring (or its connected conductor) moves in a magnetic field, it cuts magnetic field lines, thereby generating an induced current in the induction coil.

[0030] In addition, the conversion of mechanical energy into electrical energy can also be achieved using principles such as electrostatic induction and mechanical kinetic energy switches, and this manual does not impose any restrictions on this.

[0031] Because the collected piezoelectric energy is typically weak and unstable, energy storage devices are needed to store and manage it. For example, capacitors or lithium-ion batteries can be used to store electrical energy.

[0032] In real-world scenarios, the surface of system 100 may include phrases guiding users to bring their terminal devices close to and touch system 100, such as "tap to order" or "tap to pay." Terminal devices may include, but are not limited to, smartphones with NFC card reading capabilities, smartwatches, smart glasses, and other smart wearable devices; this specification does not limit this.

[0033] In some embodiments, the energy harvesting circuit 102 may also be connected to a rectifier circuit and a boost regulator circuit. The rectifier circuit converts alternating current (AC) to direct current (DC), and may include a Schottky diode rectifier bridge. The boost regulator circuit increases the output voltage to meet the voltage requirements of the radio frequency (RF) transmitter circuit 104, enabling the RF transmitter circuit 104 to transmit an excitation signal. Specifically, the current generated by the energy harvesting circuit 102 can first be converted to DC via a Schottky diode rectifier bridge, charging the capacitor, then boosted (e.g., to 3.5V) by a DC-DC converter circuit before being sent to the RF transmitter circuit 104. The RF transmitter circuit 104 can transmit an excitation signal to cause the terminal device to exit the low-power card detection (LPCD) mode based on the energy provided by the energy harvesting circuit 102.

[0034] The aforementioned terminal devices with NFC card reading functionality are typically battery-powered and highly sensitive to power consumption. To control power consumption, they usually incorporate many low-power design features, such as setting up LPCD mode, in their reader's transmission power. For example, most smartphones automatically switch to LPCD mode after the screen has been on for a period of time.

[0035] In practical applications, a mobile device will only wake up from LPCD mode and enter normal card reading mode when the terminal device detects that its emitted radio frequency signal is sensed by a nearby NFC target device, and the resulting signal strength change reaches or exceeds a preset threshold. However, in LPCD mode, the signal strength emitted by the terminal device is weakened, and the amplitude of the radio frequency signal is lower than in normal card reading mode. This causes the response amplitude of the NFC target device to the signal to decrease accordingly, making it difficult for the terminal device to accurately determine whether an NFC target device is nearby based on changes in signal amplitude. Therefore, the terminal device can be prompted to exit LPCD mode by actively emitting a stronger excitation signal.

[0036] In some embodiments, the radio frequency transmitting circuit 104 may include a first NFC chip connected to the energy harvesting circuit 102 and an excitation coil connected to the first NFC chip. The first NFC chip may transmit a carrier signal (i.e., an excitation signal) containing a specified data packet (including but not limited to commands such as card search or P2P transmission) to the excitation coil based on the boosted voltage described above. The excitation coil may then transmit the excitation signal to form a radio frequency field around the system. Optionally, the excitation signal may also be an empty carrier signal without any information to reduce the system load on the transmitted signal. The first NFC chip may be any NFC chip supporting the 13.56MHz carrier standard. The first NFC chip and the excitation coil described above may be provided by commercially available chips, and this specification does not limit their availability.

[0037] The NFC tag circuit 106 can sense NFC detection signals sent by a 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 coil can receive NFC detection signals from the terminal device and simultaneously generate an electromagnetic induction current for the second NFC chip to receive and send data. Similarly, since the 13.56MHz communication carrier frequency of NFC technology has been standardized globally, the second NFC chip can be any NFC chip supporting the 13.56MHz carrier standard. The aforementioned second NFC chip and NFC coil can be provided by commercially available chips, and this specification does not impose any limitations on this.

[0038] 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. In a food ordering scenario, the second NFC chip can contain menu and seating information. And in an access control scenario, the second NFC chip can contain authentication information.

[0039] It should be understood that the architecture and functionality of System 100 are described for illustrative purposes only and do not imply any limitation on the scope of this specification. Embodiments of this specification can also be applied to other environments with different structures and / or functionalities.

[0040] The process according to the embodiments of this specification will be described in detail below with reference to Figures 2 to 6. For ease of understanding, the specific data mentioned in the following description are exemplary and are not intended to limit the scope of this disclosure. It should be understood that the embodiments described below may also include additional actions not shown and / or actions shown may be omitted, and the scope of this disclosure is not limited in this respect.

[0041] Figure 2 shows a schematic diagram of the stacked structure of an NFC passive tag identification system 200 according to some embodiments of this specification. It is understood that the use of piezoelectric effect to convert mechanical energy into electrical energy in this embodiment is merely an example and does not constitute a limitation of this application. As shown in Figure 2, the system 200 may include, from top to bottom, a surface protective layer 202, a functional layer 204, a filling layer 206, a power supply layer 208, and a substrate layer 210. The substrate layer and the surface protective layer are the basic carrier and basic protective materials of the system 200, and can use non-metallic materials including but not limited to plastics, rubber, acrylic, and paper. Furthermore, the top of the surface protective layer 202 may display phrases to guide the user to approach and touch the system 200 using a terminal device.

[0042] As shown in Figure 2, the functional layer 204 may include an NFC tag circuit 204-1, an RF transmission circuit 204-2, and a filling material. The filling material may be PVC filling material 204-3 as shown in Figure 2. The PVC filling material 204-3 can wrap and separate the NFC tag circuit 204-1 and the RF transmission circuit 204-2.

[0043] As shown in Figure 2, the power supply layer 208 may include a piezoelectric material and a filler material. The piezoelectric material may be a piezoelectric sheet 208-1 as shown in Figure 2, and the filler material may be a PU filler material as shown in Figure 2. The PU filler material may wrap around the piezoelectric sheet 208-1 to ensure that sufficient compression deformation can be captured.

[0044] Optionally, the piezoelectric element 208-1 can be made of PZT, PVDF, or other piezoelectric materials. Lead zirconate titanate (PZT) is an important piezoelectric material, formed by sintering oxides of lead (Pb), zirconium (Zr), and titanium (Ti) at high temperatures. PZT has several different composition ratios, commonly including PZT-4, PZT-5A, PZT-5H, and PZT-8. These different PZT materials have different properties to meet different application requirements. Polyvinylidene fluoride (PVDF) is a thermoplastic engineering plastic with excellent comprehensive performance, formed by free radical polymerization of 1,1-difluoroethylene (VDF) monomer. PVDF combines the characteristics of fluoropolymers and general-purpose resins, possessing special properties such as piezoelectricity, dielectricity, and thermoelectricity. Specifically, if PZT is used in the piezoelectric element 208-1, the filler layer must be made of an anti-metal material to prevent the metal on the PZT from absorbing electromagnetic waves and affecting the recognition efficiency of the NFC tag circuit 204-1.

[0045] Since this system involves two NFC coil circuits, where the RF transmitting circuit 104 transmits a carrier signal of the RF field via an external power supply to cause the terminal device to exit LPCD mode, and the NFC tag circuit 106 generates its own electricity, stores information, and responds to the NFC detection signal of the terminal device, the circuit layout should avoid interference when the terminal device receives the excitation signal and reads the data stored in the NFC tag circuit. The circuit layout structure of some embodiments of this specification will be described below with reference to Figure 3.

[0046] Figure 3 shows a schematic circuit layout of an NFC passive tag identification system according to some embodiments of this specification. As shown in Figure 3, the radio frequency transmitting circuit 104 may include a first NFC chip 204 and an excitation coil 206, with the excitation coil 206 positioned on the outermost side. The first NFC chip 204 may be powered by the energy harvesting circuit 202 through a positive voltage supply terminal VDD and a 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 inside the excitation coil 206. In this manner, signal interference can be minimized.

[0047] In some embodiments, the radio frequency transmitting circuit 104 and the NFC tag circuit 106 can be arranged vertically or horizontally, etc. This specification does not limit the specific circuit layout.

[0048] Figure 4A shows a schematic diagram of the structure of an RF transmitting circuit 400 according to some embodiments of this specification. As shown in Figure 4A, the RF transmitting circuit 400 may include a first NFC chip 402, a first low-pass filter 404, a first matching circuit 406, a first current limiting element 408, and an excitation coil 410. The energy harvesting circuit 202 can supply power to the first NFC chip 402 through a positive voltage supply terminal VDD and a ground terminal VSS, for example, by providing a boosted voltage. The first low-pass filter 404 may include an inductor and a capacitor, and utilizes its characteristic of allowing only signals below the cutoff frequency to pass through while blocking signals above the cutoff frequency to filter out high-order harmonics of the crystal oscillator, thereby improving the stability of signal transmission.

[0049] The first matching circuit 406 can be tuned with the excitation coil 410 to adjust the impedance parameters and resonant frequency parameters. The first current-limiting element 408 may include a series resistor, which can adjust the balance between the quality factor (also known as the Q value) of the excitation coil 410 and the bandwidth of the circuit. The Q value reflects the coil's losses at the resonant frequency and is inversely proportional to the circuit bandwidth. The excitation coil 410 can send an excitation signal to excite the terminal device to exit LPCD mode.

[0050] Figure 4B shows an equivalent circuit diagram of a radio frequency transmission circuit according to some embodiments of this specification. As shown in Figure 4B, the first NFC chip 402 can be represented as chip IC1 for signal modulation and demodulation and data reception and transmission. The current generated by the energy harvesting circuit 202 flows into the positive terminal VDD of the power supply, passes through the components, and flows out from the ground VSS, forming a loop. Chip IC1 may include multiple pins, such as pin Rx for receiving external data, a transient voltage suppressor Tvss to ground to prevent circuit damage due to transient overvoltages (such as lightning strikes, electrostatic discharge, etc.), and differential signal transmission pins Tx+ and Tx- for high-speed, interference-resistant data transmission.

[0051] As shown in Figure 4B, the first low-pass filter 404 can be composed of an inductor L0 and a capacitor C0 to filter out high-order harmonics of the crystal oscillator. Capacitors C1 and C2 can form a first matching circuit 406 to adjust the impedance parameters and resonant frequency parameters. Resistor R1 can serve as a first current-limiting element 408 to adjust the Q value of coil ANT1, i.e., the excitation coil 410, and the bandwidth of the circuit.

[0052] Figure 5A shows a schematic diagram of the structure of an NFC tag circuit 500 according to some embodiments of this specification. As shown in Figure 5A, the NFC tag circuit 500 may include a second NFC chip 502, a second low-pass filter 504, a second matching circuit 506, a second current-limiting element 508, and an NFC coil 510. Similar to the radio frequency transmitting circuit 400, the second low-pass filter 504 may include an inductor and a capacitor, utilizing its characteristic of allowing only signals below the cutoff frequency to pass through while blocking signals above the cutoff frequency to filter out high-order harmonics of the crystal oscillator, thereby improving the stability of signal transmission. The second current-limiting element 508 may include a series resistor, which can adjust the balance between the quality factor (also known as the Q value) of the NFC coil 510 and the bandwidth of the circuit.

[0053] The second matching circuit 506 can tune with the NFC coil 510 and send the matched signal to the second NFC chip 502. The second NFC chip 502 then modulates the matched signal into a carrier signal and sends it to the NFC coil 510. The NFC coil can sense the NFC detection signal sent by the terminal device and send the aforementioned carrier signal.

[0054] Figure 5B shows an equivalent circuit diagram of an NFC tag circuit according to some embodiments of this specification. As shown in Figure 5B, the second NFC chip 502 can be represented as chip IC2 for signal modulation and demodulation and data reception and transmission, and stores specific information therein, including but not limited to order information, payment information, etc. Similarly, chip IC2 may include multiple pins, such as pin Rx for receiving external data, a transient voltage suppressor Tvss to ground to prevent circuit damage due to transient overvoltages (such as lightning strikes, electrostatic discharge, etc.), and differential signal transmission pins Tx+ and Tx- for high-speed, interference-resistant data transmission.

[0055] As shown in Figure 5B, the second low-pass filter 504 can be composed of an inductor L0 and a capacitor C0 to filter out high-order harmonics of the crystal oscillator. Capacitors C1 and C2 can form a second matching circuit 506 to adjust the impedance and resonant frequency parameters. Resistor R1 can serve as a second current-limiting element 508 to adjust the Q value of coil ANT2, i.e., the NFC coil 510, and the bandwidth of the circuit. This circuit operates based on the electromagnetic induction current of coil ANT2 when the terminal device is near it, without requiring an external power supply.

[0056] Figure 6 illustrates a flowchart of an NFC passive tag identification method according to some embodiments of this specification. It should be understood that method 600 may also include additional actions not shown and / or the actions shown may be omitted, and the scope of this disclosure is not limited in this respect.

[0057] As shown in Figure 6, in block 610, method 600 may include: collecting and storing electrical energy converted from the mechanical energy generated by the collision. The conversion of mechanical energy into electrical energy can be achieved using principles such as the piezoelectric effect and electromagnetic induction. Then, capacitors or lithium-ion batteries can be used to store and manage the electrical energy converted from mechanical energy.

[0058] In block 620, method 600 may include: sending an excitation signal to cause a terminal device to exit the low-power card detection (LPCD) mode, based on electrical energy converted from the mechanical energy generated by the collision. In some embodiments, the electrical energy converted from the mechanical energy can cause the NFC chip to emit a carrier signal of a radio frequency field. When the terminal device in low-power card detection (LPCD) mode approaches the radio frequency field, it will switch from LPCD mode to normal card reading mode based on the radio frequency signal. In this way, NFC card reading efficiency can be improved in NFC passive tag scenarios with low cost and low power consumption.

[0059] In box 630, method 600 may include: sensing an NFC probe signal sent by a terminal device to communicate with the terminal device. Through the action of the aforementioned radio frequency field, it is ensured that the NFC tag circuit carrying specific information can interact with a terminal device in normal card reading mode, thereby achieving high-efficiency communication.

[0060] Furthermore, embodiments of this specification also provide NFC devices corresponding to the NFC passive tag identification system. The NFC device may include any of the NFC passive tag identification systems provided in the above embodiments.

[0061] Specifically, the NFC device may include an NFC passive tag identification system, which may include an energy harvesting circuit 102, an radio frequency transmission circuit 104, and an NFC tag circuit 106. The energy harvesting circuit 102 can collect and store electrical energy converted from the mechanical energy generated by the contact between the terminal device and the system; the radio frequency transmission circuit 104 is connected to the energy harvesting circuit 102 and powered by it, and can be used to transmit an excitation signal to cause the terminal device to exit the low-power card detection (LPCD) mode; the NFC tag circuit 106 can sense the NFC detection signal sent by the terminal device to communicate with it.

[0062] In some embodiments, the energy harvesting circuit may include a piezoelectric material, and the mechanical energy generated by the collision may be converted into electrical energy based on the piezoelectric effect.

[0063] In some embodiments, the piezoelectric material may include a piezoelectric sheet.

[0064] In some embodiments, the energy harvesting circuit may include a spring and an induction coil, and the mechanical energy generated by the collision may be converted into electrical energy based on electromagnetic induction.

[0065] In some embodiments, the system may include a functional layer and a power supply layer, with the radio frequency transmitter and NFC tag module located in the functional layer and the energy harvesting circuit located in the power supply layer.

[0066] In some embodiments, the system may further include: a surface protective layer located at the top of the system; a filler layer located between the functional layer and the power supply layer; and a substrate layer located at the bottom of the system.

[0067] In some embodiments, the system may include an excitation layer, a communication layer, and a power supply layer, with the radio frequency transmission circuit located in the excitation layer, the NFC tag circuit located in the communication layer, and the energy harvesting circuit located in the power supply layer.

[0068] In some embodiments, the system may further include: a rectifier circuit connected to the energy harvesting circuit for converting alternating current to direct current; and a boost regulator circuit connected to the rectifier circuit and the radio frequency transmitting circuit for increasing the voltage input to the radio frequency transmitting circuit.

[0069] In some embodiments, the rectifier circuit may include a Schottky diode rectifier bridge.

[0070] In some embodiments, the radio frequency transmitting circuit may include: a first NFC chip connected to and powered by an energy harvesting circuit for transmitting an excitation signal; an excitation coil connected to the first NFC chip for receiving and transmitting the excitation signal from the first NFC chip; and a first matching circuit connected to the first NFC chip and the excitation coil for adjusting impedance parameters and the resonant frequency parameters of the excitation coil.

[0071] In some embodiments, the energy harvesting circuit, the first NFC chip, and the NFC tag circuit are all located inside the excitation coil.

[0072] In some embodiments, the radio frequency transmitting circuit may further include: a first filtering circuit connected to the first NFC chip for filtering out interference signals in the radio frequency transmitting 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 radio frequency transmitting circuit.

[0073] In some embodiments, the first filtering circuit may include a first low-pass filter, and the interference signal may include the higher harmonics of the crystal oscillator.

[0074] In some embodiments, the NFC tag circuit may include: an NFC coil for sensing an NFC detection signal sent by a terminal device and generating an induced current; a second NFC chip connected to the NFC coil and powered by the induced current for sending a carrier signal carrying target data to the NFC coil to communicate with the terminal device; and a first matching circuit connected to the second NFC chip and the NFC coil for adjusting impedance parameters and the resonant frequency parameters of the NFC coil.

[0075] In some embodiments, the NFC tag circuit 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.

[0076] In some embodiments, the second filtering circuit may include a second low-pass filter, and the interference signal may include the higher harmonics of the crystal oscillator.

[0077] In the embodiments described in this specification, the NFC device operates in passive mode, and the terminal device communicating with the NFC device operates in active mode.

[0078] In the embodiments of this specification, the NFC device operating in passive mode can not only passively complete communication, but also actively stimulate the terminal device to communicate in normal working mode when it collides with the terminal device.

[0079] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0080] Various embodiments of this specification have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0081] The above are merely optional embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

An NFC passive tag identification system includes: An energy harvesting circuit is used to collect and store electrical energy converted from the mechanical energy generated by the contact between the terminal device and the system. The radio frequency transmitting circuit is connected to the energy harvesting circuit and powered by the energy harvesting circuit, and is used to transmit an excitation signal for causing the terminal device to exit the low power card detection LPCD mode; as well as An NFC tag circuit is used to sense the NFC detection signal sent by the terminal device in order to communicate with the terminal device. According to claim 1, the energy harvesting circuit comprises a piezoelectric material, the piezoelectric material comprising a piezoelectric sheet, and the mechanical energy generated by the contact is converted into electrical energy based on the piezoelectric effect; or The energy harvesting circuit includes a spring and an induction coil, and the mechanical energy generated by the touch is converted into electrical energy based on electromagnetic induction. The system according to claim 1, wherein the system comprises a functional layer and a power supply layer, the radio frequency transmitting circuit and the NFC tag circuit are located in the functional layer, and the energy harvesting circuit is located in the power supply layer. The system according to claim 3, wherein the system further comprises: A surface protective layer, which is located on top of the system; A filling layer, wherein the filling layer is located between the functional layer and the power supply layer; as well as A substrate layer, which is located at the bottom of the system. The system according to claim 1, wherein the system comprises an excitation layer, a communication layer and a power supply layer, wherein the radio frequency transmitting circuit is located in the excitation layer, the NFC tag circuit is located in the communication layer, and the energy harvesting circuit is located in the power supply layer. The system according to claim 1, wherein the system further comprises: A rectifier circuit, connected to the energy harvesting circuit, is used to convert alternating current into direct current, wherein the rectifier circuit includes a Schottky diode rectifier bridge; as well as A boost regulator circuit, connected to the rectifier circuit and the radio frequency transmitting circuit, is used to increase the voltage input to the radio frequency transmitting circuit. According to claim 1, the radio frequency transmitting circuit comprises: The first NFC chip is connected to the energy harvesting circuit and powered by the energy harvesting circuit, and is used to send the excitation signal; An excitation coil, connected to the first NFC chip, is used to receive and transmit the excitation signal from the first NFC chip. A first matching circuit, connected to the first NFC chip and the excitation coil, is used to adjust the impedance parameters and the resonant frequency parameters of the excitation coil. A first filtering circuit, connected to the first NFC chip, is used to filter out interference signals in the radio frequency transmission circuit, wherein the first filtering circuit includes a first low-pass filter, and the interference signals include high-order harmonics of the crystal oscillator. as well as A first current-limiting element, connected to the excitation coil, is used to adjust the quality factor of the excitation coil and the bandwidth of the radio frequency transmission circuit. According to the system of claim 7, the energy harvesting circuit, the first NFC chip, and the NFC tag circuit are all located inside the excitation coil. The system according to claim 1, wherein the NFC tag circuit comprises: An NFC coil is used to sense the NFC detection signal sent by the terminal device and generate an induced current. The second NFC chip is connected to the NFC coil and powered by the induced current. It is used to send a carrier signal carrying target data to the NFC coil to communicate with the terminal device. A first matching circuit, connected to the second NFC chip and the NFC coil, is used to adjust the impedance parameters and the resonant frequency parameters of the NFC coil. A second filtering circuit, connected to the second NFC chip, is used to filter out interference signals in the NFC tag circuit, wherein the second filtering circuit includes a second low-pass filter, and the interference signals include high-order harmonics of the crystal oscillator. as well as A second current-limiting element, connected to the NFC coil, is used to adjust the quality factor of the NFC coil and the bandwidth of the NFC tag circuit. An NFC device, wherein the NFC device operates in passive mode and a terminal device communicating with the NFC device operates in active mode, the NFC device comprising an NFC passive tag identification system as described in any one of claims 1-9.

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