NFC electric field detection system and method and NFC device

Abstract

The present application provides a near field communication (NFC) electric field detection system and method and an NFC device. The NFC electric field detection system of the present application comprises an NFC antenna and a detection control module. The NFC antenna is configured to: when an NFC radio frequency field of a terminal device is sensed, receive a first radio frequency signal transmitted by the terminal device. The detection control module is configured to: on the basis of the first radio frequency signal, detect that the terminal device is in a low power card detection (LPCD) mode; and when it is determined that the terminal device has not read data of the NFC electric field detection system, send to the terminal device by means of the NFC antenna a second radio frequency signal used for exciting the terminal device, so as to communicate with the terminal device. Therefore, normal communication with the terminal device can be realized, improving the communication effectiveness.

Description

NFC electric field detection system, method and NFC device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on February 6, 2024, with application number: 202410172257.9 and application name: "NFC electric field detection system, method and NFC device", the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of NFC (Near Field Communication), and in particular to an NFC electric field detection system, method, and NFC device. Background Art

[0003] NFC, as a commonly used near-field communication technology, is widely used in various scenarios such as access cards, transportation cards, attendance record cards, consumption cards, and ID cards.

[0004] Currently, terminal devices typically operate in active mode, using an electric field to detect the proximity of an NFC device operating in passive mode. However, to reduce power consumption and increase battery life, some terminal devices switch to LPCD (Low Power Card Detection) mode after the screen is on for a period of time. Once in LPCD mode, if the antenna coupling area is insufficient or the electric field changes are not significant, it can be difficult for the terminal device to exit LPCD mode, making normal communication difficult.

[0005] Summary of the Invention

[0006] The present application provides an improved NFC electric field detection system, method, and NFC device.

[0007] This application provides an NFC electric field detection system, including:

[0008] A near field communication (NFC) antenna, configured to receive a first radio frequency signal transmitted by a terminal device when sensing an NFC radio frequency field of the terminal device;

[0009] A detection control module is used to detect that the terminal device is in a low-power card detection (LPCD) mode based on the first radio frequency signal; and in the case of abnormal communication with the terminal device, send a second radio frequency signal for stimulating the terminal device to the terminal device through the NFC antenna to communicate with the terminal device.

[0010] Furthermore, the NFC antenna is configured to sense the field strength of the NFC radio frequency field when the terminal device transmits an NFC signal, thereby generating an electrical signal corresponding to the field strength;

[0011] Accordingly, the detection control module includes a signal sampling circuit and a control circuit connected to the signal sampling circuit;

[0012] The signal sampling circuit samples the electrical signal;

[0013] The control circuit is configured to obtain characteristic information of the NFC radio frequency field of the terminal device based on the value of the electrical signal; detect that the terminal device is in the LPCD mode when the amplitude strength of the characteristic information meets the threshold of the LPCD mode; and send the second radio frequency signal to the terminal device when the terminal device does not read data from the NFC electric field detection system.

[0014] Furthermore, the NFC antenna further includes an NFC coil and a grounded noise filter terminal;

[0015] NFC coil, used to sense radio frequency signals;

[0016] The noise filter terminal is used to filter out the noise signal of the radio frequency signal induced by the NFC coil, so that the NFC antenna receives a normal signal except for the noise.

[0017] Furthermore, the NFC coil includes at least a three-terminal coil; the noise filtering terminal is placed at the physical center of the antenna.

[0018] Furthermore, the at least three-terminal coil includes an odd-terminal coil, the noise filtering terminal is one noise filtering terminal, and the one noise filtering terminal is placed at the physical center of the NFC antenna; the number of terminals of the odd-terminal coil is greater than or equal to the number of terminals of the three-terminal coil;

[0019] or,

[0020] The at least three-terminal coil includes an even-numbered terminal coil, and accordingly, the noise filtering terminals are two noise filtering terminals, and the two noise filtering terminals are placed at the physical center of the NFC antenna; the number of terminals of the even-numbered terminal coil is greater than the number of terminals of the three-terminal coil.

[0021] Furthermore, the detection control module is configured to detect, based on the first radio frequency signal, that the terminal device is in a low power consumption card detection (LPCD) mode; and generate a signal for stimulating the terminal device in the event of abnormal communication with the terminal device;

[0022] The NFC electric field detection system further includes: an NFC module, configured to receive the signal for stimulating the terminal device, tune with the NFC antenna, and send the modulated second radio frequency signal to the terminal device via the NFC antenna.

[0023] Furthermore, the NFC module includes a matching circuit and a modulation and demodulation unit connected to the matching circuit;

[0024] The matching circuit is configured to tune with the NFC antenna and send a matched signal to the modem unit;

[0025] The modulation and demodulation unit is configured to receive the matched signal, modulate the matched signal onto a carrier signal to obtain the second radio frequency signal, and send the second radio frequency signal to the NFC antenna;

[0026] The NFC antenna is further configured to send the second radio frequency signal.

[0027] Furthermore, the matching circuit is arranged after the wiring of the signal sampling circuit;

[0028] The matching circuit includes an impedance element, which is used to adjust impedance parameters and resonant frequency parameters, and is also used to adjust the parasitic effect of the matching circuit on the routing of the signal sampling circuit.

[0029] Furthermore, the signal sampling circuit includes an amplitude signal sampling circuit, a voltage sampling circuit or a current sampling circuit of an analog-to-digital converter ADC.

[0030] Furthermore, the detection control module is also used to detect that the terminal device is in the LPCD mode based on the first RF signal, and in the case of abnormal communication with the terminal device, determine the terminal type of the terminal device according to the transmission period of the electric field of the terminal device; and send the second RF signal to the terminal device based on the terminal type.

[0031] This application provides an NFC electric field detection method, including:

[0032] When an NFC radio frequency field of a terminal device is sensed, receiving a first radio frequency signal transmitted by the terminal device;

[0033] Based on the first radio frequency signal, it is detected that the terminal device is in a low-power card detection LPCD mode; in the case of abnormal communication with the terminal device, a second radio frequency signal for stimulating the terminal device is sent to the terminal device through the NFC antenna to communicate with the terminal device.

[0034] The present application provides 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. The NFC device includes the NFC electric field detection system as described in any one of the above items.

[0035] The present application provides a machine-readable storage medium having a program stored thereon. When the program is executed by a processor, the method described in any one of the above items is implemented.

[0036] The present application provides a computer program product, comprising a computer program / instruction, which implements any of the above methods when executed by a processor.

[0037] In some embodiments, the NFC electric field detection system of the present application includes an NFC antenna and a detection control circuit. The NFC antenna is configured to receive a first radio frequency signal transmitted by a terminal device upon sensing the terminal device's NFC radio frequency field. The detection control module is configured to detect, based on the first radio frequency signal, that the terminal device is in low-power card detection (LPCD) mode; and, in the event of abnormal communication with the terminal device, transmit a second radio frequency signal to the terminal device via the NFC antenna to stimulate the terminal device, thereby enabling communication with the terminal device.

[0038] In the embodiment of the present application, the NFC antenna receives a first radio frequency signal transmitted by a terminal device, and the detection control circuit sends a second radio frequency signal for stimulating the terminal device. Thus, if the terminal device has difficulty exiting LPCD mode, the second radio frequency signal for stimulating the terminal device can be used to wake the terminal device and put it into normal card detection mode, thereby enabling communication with the terminal device. This ensures normal communication with the terminal device and improves communication efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG1 is a schematic structural diagram of an NFC electric field detection system according to an embodiment of the present application;

[0040] FIG2 is a schematic diagram showing a specific structure of the NFC electric field detection system shown in FIG1 ;

[0041] FIG3 is a flow chart of an NFC electric field detection method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. When the following description refers to the drawings, identical numbers in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Instead, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0043] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0044] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0045] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0046] It should be noted that in other embodiments, the steps of the corresponding method are not necessarily performed in the order shown and described in this specification. In some other embodiments, the method may include more or fewer steps than those described in this specification. In addition, a single step described in this specification may be broken down into multiple steps for description in other embodiments, and multiple steps described in this specification may be combined into a single step for description in other embodiments.

[0047] In order to solve the technical problem that it is difficult for a terminal device to exit the LPCD mode and thus it may be difficult to communicate normally, an embodiment of the present application provides an NFC electric field detection system including an NFC antenna and a detection control circuit.

[0048] The NFC antenna is configured to receive a first radio frequency signal transmitted by a terminal device when it senses the terminal device's NFC radio frequency field. The detection control module is configured to detect, based on the first radio frequency signal, that the terminal device is in low-power card detection (LPCD) mode; and, if communication with the terminal device is not normal, to transmit a second radio frequency signal to the terminal device via the NFC antenna to activate the terminal device, thereby enabling communication with the terminal device.

[0049] In the embodiment of the present application, the NFC antenna receives a first radio frequency signal transmitted by a terminal device, and the detection control circuit sends a second radio frequency signal for stimulating the terminal device. Thus, if the terminal device has difficulty exiting LPCD mode, the second radio frequency signal for stimulating the terminal device can be used to wake the terminal device and put it into normal card detection mode, thereby enabling communication with the terminal device. This ensures normal communication with the terminal device and improves communication efficiency.

[0050] The NFC electric field detection system of the embodiment of the present application can be applied to an NFC device. The NFC device operates in a passive mode (hereinafter also referred to as an NFC passive device), and the terminal device communicating with the NFC device operates in an active mode.

[0051] It should be noted that the terminal device may be, but is not limited to, a mobile terminal or a fixed card swiping device. For example, the mobile terminal may be, but is not limited to, a mobile phone. The fixed card swiping device may be a card swiping machine on a bus.

[0052] FIG1 is a schematic structural diagram of an NFC electric field detection system 10 according to an embodiment of the present application.

[0053] As shown in FIG1 , the NFC electric field detection system 10 includes an NFC antenna 21 (hereinafter referred to as the antenna) and a detection control module 22 connected to the NFC antenna 21.

[0054] The NFC antenna 21 is configured to receive a first radio frequency signal transmitted by the terminal device when sensing the NFC radio frequency field of the terminal device. The first radio frequency signal herein may include, but is not limited to, an NFC signal.

[0055] The detection control module 22 is configured to detect that the terminal device is in the low-power card detection (LPCD) mode based on the first radio frequency signal; and in the case of abnormal communication with the terminal device, to send a second radio frequency signal for stimulating the terminal device to the terminal device through the NFC antenna 21 to communicate with the terminal device.

[0056] The above LPCD mode is for the terminal device to enter low power mode after a certain period of unlocking interval in order to save power consumption when detecting NFC slave devices, and then the card detection will also enter LPCD mode.

[0057] The second RF signal is a specific signal for stimulating the terminal device. The frequency band of the specific signal is between 12 MHz and 14 MHz. In other words, when the terminal device receives the specific signal for stimulating, it wakes up the LPCD mode and enters the normal card detection mode.

[0058] The normal card detection mode mentioned above means that the mobile terminal maintains full power card detection for a period of time after unlocking to improve NFC speed and success rate. This is also known as normal card detection mode. Both the LPCD and normal detection modes above use a 13.56MHz sine wave emitted by the terminal device, but with different transmission times and amplitudes, coupling energy through the coil.

[0059] Since the second RF signal is used for excitation, it can be a carrier-free signal and does not contain any information. This not only reduces the system burden of the transmission signal, but also improves the efficiency of information transmission. For example, the operating frequency band of NFC is 13.56 MHz. The second RF signal can be, but is not limited to, a 13.56 MHz carrier-free signal. In this way, when the terminal device receives the 13.56 MHz RF signal, it wakes up the LPCD mode and enters the normal card detection mode.

[0060] Of course, after the above-mentioned detection control module 22 sends the second radio frequency signal for stimulating the terminal device to the terminal device through the NFC antenna 21, if the communication status of the terminal device has not returned to normal communication, the above-mentioned second radio frequency signal can be resent to the terminal device through the NFC antenna 21 multiple times until the terminal device is awakened and is in normal card detection mode, and normal communication with the terminal device is carried out.

[0061] After the detection control module 22 transmits the second radio frequency signal for stimulating the terminal device to the terminal device via the NFC antenna 21, if the terminal device's communication status returns to normal, the terminal device can read the predetermined information in the NFC electric field detection system 10. This predetermined information is information pre-set in the NFC device. In this way, the terminal device can read the predetermined information to achieve communication between the terminal device and the NFC device.

[0062] In some examples, the detection control module 22 is further configured to detect, based on the first RF signal, that the terminal device is in the LPCD mode. In the event of abnormal communication with the terminal device, the detection control module 22 determines the terminal type of the terminal device based on the transmission period of the terminal device's electric field; and transmits a second RF signal to the terminal device to stimulate the terminal device based on the terminal type. In this manner, by determining the terminal type, the second RF signal can be transmitted based on the terminal type, thereby improving the accuracy and timeliness of RF signal transmission.

[0063] Different terminal devices have different electric field transmission periods, and this period can be used to distinguish terminal types. Terminal types in this article include, but are not limited to, different models of terminal devices produced by different manufacturers. For example, the electric field transmission period of an iPhone is generally around 300ms.

[0064] Furthermore, based on the terminal type, a second radio frequency signal for stimulating the terminal type is determined from the correspondence between different terminal types and radio frequency signals used for stimulation; and the second radio frequency signal is sent to the terminal device.

[0065] In the embodiment of the present application, the introduction of the detection control module 22 enables an NFC device operating in passive mode to have external sensing capabilities. After the NFC antenna 21 senses, it has a response strategy, such as emitting an excitation field or other action carrier signal. The NFC device can guide or complete the desired communication under conditions of poor communication quality.

[0066] FIG2 is a schematic diagram showing a specific structure of the NFC electric field detection system 10 shown in FIG1 .

[0067] As shown in Figure 2, the NFC antenna 21 includes an NFC antenna 21, which is used when the terminal device 20 transmits an NFC signal. The NFC antenna 21 senses the field strength of the NFC radio frequency field and forms an electrical signal corresponding to the field strength. Furthermore, the NFC antenna 21 includes multiple signal output terminals. The multiple signal output terminals shown in Figure 2 include a signal output terminal A1 and a signal output terminal B1, and the electrical signals are output through the multiple signal output terminals. The above-mentioned NFC antenna 21 can sense the presence of the field strength of the NFC radio frequency field in real time, thereby avoiding omissions and achieving the accuracy of the field strength of the NFC radio frequency field sensed by the NFC antenna 21.

[0068] Accordingly, the detection control module 22 includes a signal sampling circuit 221 and a control circuit 222 connected to the signal sampling circuit 221.

[0069] The signal sampling circuit 221 is used to sample electrical signals. Continuing with FIG2 , the signal sampling circuit 221 includes an acquisition input terminal connected to the signal output terminal. The signal sampling circuit 221 acquires the electrical signal through the acquisition input terminal. Exemplarily, the acquisition input terminal includes a sampling input terminal A2 and a sampling input terminal B2. In the example shown in FIG2 , the sampling input terminal B2 is connected to the signal output terminal B1, thereby completing the signal acquisition of the signal output terminal B1 of the antenna. In other examples, the sampling input terminal A2 is connected to the signal output terminal A1, thereby completing the signal acquisition of the signal output terminal A1 of the antenna. The acquisition input terminal can be connected to either end of the signal output terminal A1 or the signal output terminal B1.

[0070] Furthermore, the signal sampling circuit 221 includes an amplitude signal sampling circuit 221 of an ADC (Analog-to-Digital Converter), a voltage acquisition circuit, or a current acquisition circuit. Thus, the amplitude signal sampling circuit 221 can sample an amplitude signal, such as a level amplitude. The voltage acquisition circuit or the current acquisition circuit can also acquire other forms of current, such as induced current. For example, the current value can be obtained by combining the level amplitude with a resistor. The signal sampling circuit 221 transmits the sampled signal to the control circuit 222.

[0071] The control circuit 222 is configured to obtain characteristic information of the NFC radio frequency field of the terminal device 20 based on the value of the electrical signal; the characteristic information of the NFC radio frequency field includes information related to the period and amplitude of the radio frequency field transmitted by the terminal device 20. If the amplitude of the characteristic information meets the threshold for the LPCD mode, the control circuit 222 detects that the terminal device 20 is in LPCD mode. Furthermore, if it is determined that the terminal device 20 has not read data from the NFC electric field detection system 10, the control circuit 222 is configured to send a second radio frequency signal to the terminal device 20 to stimulate the terminal device 20. The failure to read data from the NFC electric field detection system 10 indicates that communication with the terminal device 20 is not normal.

[0072] The threshold values ​​can be set based on the LPCD mode and the normal card detection mode, and are not limited to these settings. For example, if the amplitude strength of the characteristic information meets the threshold value for the LPCD mode, such as, but not limited to, a level below 1 volt, it can be detected that the terminal device 20 is in the LPCD mode. If the amplitude strength of the characteristic information meets the threshold value for the LPCD mode, such as, but not limited to, a level above 5 volts, it can be detected that the terminal device 20 is in the normal card detection mode.

[0073] The control circuit 222 may include, but is not limited to, a control chip and its peripheral circuits. For example, the control chip may include, but is not limited to, an MCU (Micro Controller Unit). The peripheral circuits may include, but are not limited to, electronic components such as capacitors, resistors, and capacitors to process signals.

[0074] In an embodiment of the present application, the required signal can be collected from the antenna through the signal sampling circuit 221. By combining the detection control module 22 with the above-mentioned NFC antenna 21, a signal sampling circuit 221 is added to the detection control module 22, which can complete the lack of sensing of the source of the external terminal device 20 that can emit the radio frequency field, and further complete the subsequent related strategies through the detection control module 22.

[0075] As shown in FIG. 2 , the NFC antenna 21 may include the following types of NFC antennas 21 .

[0076] In the embodiment of the NFC antenna 21 shown in FIG2 , the NFC antenna 21 further includes an NFC coil and a grounded noise filter terminal. The NFC antenna 21 comprising the noise filter terminal C1 , the signal output terminal A1 , and the signal output terminal B1 may also be referred to as a three-terminal antenna.

[0077] The NFC coil is used to sense radio frequency signals; the noise filter terminal is used to filter out noise signals from the radio frequency signals sensed by the NFC coil, so that the NFC antenna 21 receives normal signals except for the noise.

[0078] It should be noted that the above-mentioned noise signal can be, but is not limited to, low-frequency noise. In some examples, the noise filter terminal C1 of the above-mentioned NFC antenna 21 is connected to the input terminal C2 of the NFC module 23, and then connected to the single-board ground to filter out the low-frequency noise received on the antenna, so that only normal signals for communication are received. In other examples, the noise filter terminal C1 of the above-mentioned NFC antenna 21 is connected to the input terminal C2 of the NFC module 23, and the link can be connected in series with devices such as inductors and capacitors, and then connected to the single-board ground to filter out the low-frequency noise received on the antenna, so that only normal signals for communication are received. These normal signals for communication are purer than the signals before noise filtering. This three-terminal antenna receives very little noise signal, or even no noise signal, which facilitates high-precision detection.

[0079] The aforementioned NFC coil comprises at least three terminals; the noise filter terminal is placed at the physical center of the antenna. This maintains balance among the other signal output terminals. Furthermore, the noise filter terminal C1 is placed at the physical center of the antenna, thereby maintaining balance between signal output terminals A1 and B1. As shown in Figure 2, signal output terminals A1 and B1 form two conductive terminals of a coiled conductor, and the noise filter terminal C1 can be placed at the midpoint of this conductor.

[0080] In some embodiments of the at least three-terminal coil, the at least three-terminal coil includes an odd-terminal coil, the noise filtering terminal is one noise filtering terminal, and the one noise filtering terminal is placed at the physical center of the NFC antenna 21; the number of terminals of the odd-terminal coil is greater than or equal to the number of terminals of the three-terminal coil.

[0081] In some other embodiments of the at least three-terminal coil, the at least three-terminal coil includes an even-numbered terminal coil, and accordingly, the noise filtering terminals are two noise filtering terminals, and the two noise filtering terminals are placed at the physical center of the above-mentioned NFC antenna 21; the number of terminals of the even-numbered terminal coil is greater than the number of terminals of the three-terminal coil.

[0082] In the embodiment of the present application, the three-terminal antenna proposed in the NFC antenna 21 has a noise filter terminal C1 connected to the input terminal C2 of the NFC module 23 and to the board ground, thereby filtering out noise in a certain frequency band, and thus transmitting a purer communication signal to the signal sampling circuit 221, enabling the control circuit 222 to make accurate decisions.

[0083] In another embodiment of the above-mentioned NFC antenna 21, the above-mentioned NFC antenna 21 only includes two signal output terminals, namely, signal output terminal A1 and signal output terminal B1. In this way, the NFC antenna 21 coil is double-ended. While the coil of the NFC antenna 21 senses the NFC signal (13.56MHz), it also senses other signals and forms noise in the circuit, affecting subsequent sampling. In this solution, the signal output terminal A1 and the signal output terminal B1 of the near field communication NFC antenna 21 are respectively connected to the sampling input terminal A2 and the sampling input terminal B2 of the NFC module 23. When the input signal is large enough, the noise can be ignored. In this way, the scope of application of the NFC antenna 21 is improved.

[0084] Continuing with Figure 2 , the detection control module 22 is configured to detect, based on the first RF signal, that the terminal device 20 is in the low-power card detection (LPCD) mode; and, in the event of abnormal communication with the terminal device 20, to generate a signal for energizing the terminal device 20. The NFC electric field detection system 10 also includes an NFC module 23, configured to receive the signal for energizing the terminal device 20, tune the NFC antenna 21, and transmit a second RF signal to the terminal device 20 via the NFC antenna 21. This allows the signal generated by the detection control module 22 to be processed by the NFC module 23 before being transmitted via the NFC antenna 21, ensuring effective signal transmission.

[0085] 2 , the NFC module 23 and the detection control module 22 can achieve bidirectional communication via the control bus. Furthermore, the NFC module 23 is also configured to demodulate the received radio frequency signal and send the demodulated signal to the control circuit 222 .

[0086] Continuing with FIG2 , the NFC module 23 includes a matching circuit 231 and a modulation and demodulation unit 232 connected to the matching circuit 231.

[0087] The matching circuit 231 is used to tune with the NFC antenna 21 and send the matched signal to the modem unit 232. The matched signal can be a signal after tuning and filtering out electromagnetic interference. The modem unit 232 is used to receive the signal for stimulating the terminal device 20, obtain a second radio frequency signal based on the signal, and send the second radio frequency signal to the NFC antenna 21. The NFC antenna 21 is also used to send the second radio frequency signal. The signal for stimulating the terminal device 20 is an instruction for instructing the modem unit 232 to transmit the second radio frequency signal, so that after receiving the instruction, the modem unit 232 can transmit the second radio frequency signal with a preset frequency (around 13.56 MHz), amplitude and duration.

[0088] In some examples, the matching circuit 231 is located after the signal sampling circuit 221. The matching circuit 231 includes an impedance element for adjusting impedance parameters and resonant frequency parameters, and for adjusting the parasitic effects of the matching circuit 231 on the signal sampling circuit 221's routing. The impedance element may include, but is not limited to, a variable capacitor, a variable inductor, and a variable resistor. Furthermore, the variable capacitor resonates with the parasitic inductance of the NFC antenna 21 and filters out electromagnetic interference. The matching circuit 231 also transmits the second RF signal, after filtering out interference, to the modem unit 232. In this way, after the routing of the matching circuit 231 and the routing of the signal sampling circuit 221 are arranged, the impedance parameters of the impedance element are adjusted to change the parasitic effects of the matching circuit 231 on the routing of the signal sampling circuit 221.

[0089] In the embodiment of the present application, the matching circuit 231 is placed after the routing of the signal sampling circuit 221. By adjusting the impedance parameters of the impedance element, the parasitic effect of the matching circuit 231 on the routing of the signal sampling circuit 221 is reduced. In this way, the parasitic effect of the matching circuit 231 on the routing of the signal sampling circuit 221 can be reduced. Furthermore, the parasitic effect of the matching circuit 231 on the routing of the signal sampling circuit 221 is avoided.

[0090] The application scenarios of the NFC electric field detection system 10 of the present application can include, but are not limited to, UnionPay, aggregated payment equipment manufacturers, and mobile phone companies related to the research and development and production of NFC devices.

[0091] Based on the same application concept as the above-mentioned NFC electric field system, the embodiment of the present application further proposes an NFC electric field detection method, as shown in FIG3 , the above-mentioned NFC electric field detection method includes the following steps 310 to 320:

[0092] Step 310: When the NFC radio frequency field of the terminal device is sensed, a first radio frequency signal transmitted by the terminal device is received.

[0093] Step 320: Based on the first radio frequency signal, it is detected that the terminal device is in the low power consumption card detection LPCD mode; in the case of abnormal communication with the terminal device, a second radio frequency signal for stimulating the terminal device is sent to the terminal device through the NFC antenna to communicate with the terminal device.

[0094] In some embodiments, the above step 310 may further include: when the terminal device transmits an NFC signal, the NFC antenna senses the field strength of the NFC radio frequency field and generates an electrical signal corresponding to the field strength;

[0095] Accordingly, the detection control module includes a signal sampling circuit and a control circuit connected to the signal sampling circuit. The above 320 may further include the signal sampling circuit sampling an electrical signal; the control circuit obtaining characteristic information of the NFC radio frequency field of the terminal device based on the sampled value of the electrical signal; detecting that the terminal device is in LPCD mode when the amplitude strength of the characteristic information meets the threshold of the LPCD mode; and sending a second radio frequency signal to the terminal device to stimulate the terminal device when it is determined that the terminal device has not read data from the NFC electric field detection system.

[0096] In some embodiments, the above 320 may further include detecting that the terminal device is in a low-power card detection (LPCD) mode based on the first radio frequency signal; and generating a signal for stimulating the terminal device when abnormal communication with the terminal device occurs. The NFC electric field detection method also includes receiving the signal for stimulating the terminal device, tuning the NFC antenna, and transmitting the modulated second radio frequency signal to the terminal device via the NFC antenna.

[0097] An embodiment of the present application further provides an NFC device, the NFC device operates in a passive mode, a terminal device communicating with the NFC device operates in an active mode, and the NFC device includes any one of the above NFC electric field detection systems.

[0098] In the embodiment of the present application, the NFC device operating in the passive mode can not only complete the communication passively, but also actively stimulate the terminal device to wake up the terminal device for communication, and the success rate does not need to rely entirely on the terminal device.

[0099] In the description of this application, it should be understood that the terms "first," "second," etc. are used for descriptive purposes only and should not be construed to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first," "second," etc. may explicitly or implicitly include at least one such feature. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically specified.

[0100] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0101] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0102] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the inventive concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. An NFC electric field detection system, characterized in that: include: A near field communication (NFC) antenna, configured to receive a first radio frequency signal transmitted by a terminal device when sensing an NFC radio frequency field of the terminal device; a detection control module, configured to detect, based on the first radio frequency signal, that the terminal device is in a low power consumption card detection (LPCD) mode; When it is determined that the terminal device has not read the data of the NFC electric field detection system, a second radio frequency signal for stimulating the terminal device is sent to the terminal device through the NFC antenna to communicate with the terminal device.

2. The NFC electric field detection system according to claim 1, wherein: The NFC antenna is configured to sense the field strength of the NFC radio frequency field when the terminal device transmits an NFC signal, and generate an electrical signal corresponding to the field strength; Accordingly, the detection control module includes a signal sampling circuit and a control circuit connected to the signal sampling circuit; the signal sampling circuit samples the electrical signal; The control circuit is configured to obtain characteristic information of the NFC radio frequency field of the terminal device based on the sampled value of the electrical signal; detect that the terminal device is in the LPCD mode when the amplitude strength of the characteristic information meets the threshold of the LPCD mode; and send the second radio frequency signal to the terminal device via the NFC antenna when it is determined that the terminal device has not read data from the NFC electric field detection system.

3. The NFC electric field detection system according to claim 2, wherein: The NFC antenna further includes an NFC coil, and the NFC coil includes a grounded noise filtering terminal.

4. The NFC electric field detection system according to claim 3, wherein: The NFC coil includes at least a three-terminal coil; the noise filtering terminal is placed at the physical center of the antenna.

5. The NFC electric field detection system according to claim 4, wherein: The at least three-terminal coil includes an odd-terminal coil, the noise filtering terminal is one noise filtering terminal, and the one noise filtering terminal is located at the physical center of the NFC antenna; the number of terminals of the odd-terminal coil is greater than or equal to the number of terminals of the three-terminal coil; or, The at least three-terminal coil includes an even-numbered terminal coil, and accordingly, the noise filtering terminals are two noise filtering terminals, and the two noise filtering terminals are placed at the physical center of the NFC antenna; the number of terminals of the even-numbered terminal coil is greater than the number of terminals of the three-terminal coil.

6. The NFC electric field detection system according to any one of claims 1 to 5, characterized in that: The detection control module is configured to detect, based on the first radio frequency signal, that the terminal device is in a low power consumption card detection (LPCD) mode; generating a signal for stimulating the terminal device in case of abnormal communication with the terminal device; The NFC electric field detection system further includes: an NFC module, configured to receive the signal for stimulating the terminal device, tune with the NFC antenna, and send the second radio frequency signal to the terminal device via the NFC antenna.

7. The NFC electric field detection system according to claim 6, wherein: The NFC module includes a matching circuit and a modulation and demodulation unit connected to the matching circuit; The matching circuit is used to tune with the NFC antenna; The modulation and demodulation unit is configured to send the second radio frequency signal to the NFC antenna according to the signal used to stimulate the terminal device; The NFC antenna is further configured to send the second radio frequency signal.

8. The NFC electric field detection system according to claim 7, wherein: The matching circuit is arranged after the wiring of the signal sampling circuit; The matching circuit includes an impedance element, which is used to adjust impedance parameters and resonant frequency parameters, and is also used to adjust the parasitic effect of the matching circuit on the routing of the signal sampling circuit.

9. The NFC electric field detection system according to claim 2, wherein: The signal sampling circuit includes an amplitude signal sampling circuit, a voltage sampling circuit or a current sampling circuit of an analog-to-digital converter ADC.

10. The NFC electric field detection system according to claim 1, wherein: The detection control module is further configured to detect, based on the first radio frequency signal, that the terminal device is in the LPCD mode, and, if it is determined that the terminal device has not read data from the NFC electric field detection system, determine the terminal type of the terminal device according to a transmission period of the electric field of the terminal device; The second radio frequency signal is sent to the terminal device according to the terminal type.

11. A NFC electric field detection method, characterized in that: include: When an NFC radio frequency field of a terminal device is sensed, receiving a first radio frequency signal transmitted by the terminal device; According to the first radio frequency signal, detecting that the terminal device is in a low power consumption card detection (LPCD) mode; When it is determined that the terminal device has not read the data of the NFC electric field detection system, a second radio frequency signal for stimulating the terminal device is sent to the terminal device through the NFC antenna to communicate with the terminal device.

12. An NFC device, characterized in that: 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 NFC electric field detection system according to any one of claims 1 to 10.

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