NFC electric field detection system, method, NFC device, and computer program

Abstract

To provide a near field communication (NFC) electric field detection system that achieves normal communication with a terminal device that is in a low power card detection (LPCD) mode.SOLUTION: An NFC electric field detection system includes an NFC antenna 21 that receives a first radio frequency signal emitted by a terminal device when an NFC radio frequency field of the terminal device is sensed, and a detection control module that is used to detect that the terminal device is in an LPCD mode according to the first radio frequency signal, and that sends a second radio frequency signal to excite the terminal device to the terminal device through the NFC antenna so as to communicate with the terminal device when emergency communication is to be performed with the terminal device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to the field of NFC (Near Field Communication), and more particularly to an NFC electric field detection system, method and NFC device. [Background technology]

[0002] NFC is a commonly used short-range communication technology that is widely used in various applications such as access cards, transportation cards, attendance cards, consumption cards, and ID cards. Summary of the Invention [Problem to be solved by the invention]

[0003] Currently, terminal devices generally operate in active mode, emitting an electric field to monitor whether an NFC device operating in passive mode is approaching. However, some terminal devices operate in Low Power Card Detection (LPCD) mode after a certain period of time has passed since the screen was turned on in order to reduce power consumption and increase operating time. Once operating in LPCD mode, if the antenna coupling area is insufficient or the change in the electric field is not significant, the terminal device may have difficulty exiting LPCD mode, which may result in difficulty in normal communication.

[0004] The present application provides improved NFC electric field detection systems, methods and NFC devices. [Means for solving the problem]

[0005] This application is a near field communication (NFC) antenna for receiving a first radio frequency signal emitted by a terminal device when the NFC antenna senses an NFC radio frequency field of the terminal device; and a detection control module used to detect that the terminal device is in a low power card detection LPCD mode according to the first radio frequency signal, and when performing emergency communication with the terminal device, the detection control module sends a second radio frequency signal to the terminal device through the NFC antenna to excite the terminal device so as to communicate with the terminal device.

[0006] Furthermore, the NFC antenna is used to sense a field strength of the NFC radio frequency field when the terminal device emits an NFC signal, and to form an electrical signal corresponding to the field strength; Accordingly, the detection control module comprises 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 used to obtain characteristic information of the NFC radio frequency field of the terminal device according to the numerical value of the electrical signal, and detects that the terminal device is in the LPCD mode when the amplitude intensity of the characteristic information meets the threshold of the LPCD mode, and sends the second radio frequency signal to the terminal device when the terminal device does not read data of the NFC electric field detection system.

[0007] Furthermore, the NFC antenna includes an NFC coil and a grounded noise filter terminal, 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 receives normal signals other than noise.

[0008] Furthermore, the NFC coil includes at least a three-terminal coil, and the noise filter terminal is located at the physical center of the antenna.

[0009] Furthermore, the at least three-terminal coil includes an odd-terminal coil, the noise filter terminal is one noise filter terminal arranged at the physical center of the NFC antenna, and the number of terminals of the odd-terminal coil is equal to or greater than the number of terminals of the three-terminal coil; or, The at least three-terminal coil includes an even-terminal coil, and accordingly, the noise filter terminals are two noise filter terminals arranged at the physical center of the NFC antenna, and the number of terminals of the even-terminal coil is greater than the number of terminals of the three-terminal coil.

[0010] Furthermore, the detection control module is used to detect that the terminal device is in a low power card detection LPCD mode according to the first radio frequency signal, and generates a signal to excite the terminal device when performing emergency communication with the terminal device.

[0011] The NFC electric field detection system further comprises an NFC module used for receiving the signal for exciting the terminal device, tuning with the NFC antenna, and transmitting the modulated second radio frequency signal to the terminal device through the NFC antenna.

[0012] The NFC module further includes a matching circuit and a modulation / demodulation unit connected to the matching circuit; the matching circuit is used to tune with the NFC antenna and transmit a matched signal to the modulation / demodulation unit; the modulation / demodulation unit is used for receiving the matched signal, modulating the matched signal onto a carrier signal, and then obtaining the second radio frequency signal, and transmitting the second radio frequency signal to the NFC antenna; The NFC antenna is further used to transmit the second radio frequency signal.

[0013] Furthermore, the matching circuit is located after the trace of the signal sampling circuit; The matching circuit comprises impedance elements used to adjust impedance parameters and resonant frequency parameters, and further impedance elements used to adjust the parasitic effects of the matching circuit on traces of the signal sampling circuit.

[0014] Furthermore, the signal sampling circuit includes an amplitude signal sampling circuit of an analog-to-digital converter ADC, a voltage acquisition circuit, or a current acquisition circuit.

[0015] Furthermore, the detection control module is further used to detect that the terminal device is in the LPCD mode according to the first radio frequency signal, and when performing emergency communication with the terminal device, to determine the terminal type of the terminal device according to the transmission period of the electric field of the terminal device, and transmit the second radio frequency signal to the terminal device according to the terminal type.

[0016] This application is receiving a first radio frequency signal emitted by a terminal device when sensing an NFC radio frequency field of the terminal device; detecting that the terminal device is in a low power consumption card detection LPCD mode according to the first radio frequency signal; and transmitting a second radio frequency signal to the terminal device through the NFC antenna to excite the terminal device to communicate with the terminal device when emergency communication is to be performed with the terminal device.

[0017] The present application provides an NFC device, the NFC device operating in a passive mode, a terminal device communicating with the NFC device operating in an active mode, the NFC device comprising any of the NFC electric field detection systems described above.

[0018] The present application provides a machine-readable storage medium having stored thereon a program that, when executed by a processor, implements any of the above methods.

[0019] The present application provides a computer program product comprising computer programs / instructions which, when executed by a processor, implement any of the methods described above.

[0020] In some embodiments, the NFC electric field detection system of the present application includes an NFC antenna and a detection control circuit, wherein the near field communication NFC antenna is used to receive a first radio frequency signal emitted by the terminal device when sensing the NFC radio frequency field of the terminal device, and the detection control module is used to detect that the terminal device is in a low power card detection LPCD mode according to the first radio frequency signal, and when performing emergency communication with the terminal device, transmits a second radio frequency signal to the terminal device through the NFC antenna to excite the terminal device to communicate with the terminal device. [Effects of the Invention]

[0021] In an embodiment of the present invention, the NFC antenna receives a first radio frequency signal emitted by the terminal device, and the detection control circuit transmits a second radio frequency signal to excite the terminal device. In this way, when the terminal device is difficult to exit the LPCD mode, the second radio frequency signal to excite the terminal device wakes up the terminal device and puts it into the normal card detection mode so as to communicate with the terminal device. This enables normal communication with the terminal device to be realized and improves the effectiveness of communication. [Brief explanation of the drawings]

[0022] [Figure 1] 1 shows a schematic diagram of the configuration of an NFC electric field detection system according to an embodiment of the present application. [Figure 2] A specific configuration schematic diagram of the NFC electric field detection system shown in FIG. 1 is shown. [Figure 3] 1 shows a flowchart of an NFC electric field detection method provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0023] Reference will now be made in detail to exemplary embodiments illustrated in the drawings. When the following description refers to the drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise noted. The embodiments described in the following exemplary embodiments do not represent all embodiments that may be consistent with the present application. Rather, they are merely examples of apparatus and methods that may be consistent with certain aspects of the present application, as detailed in the appended claims.

[0024] All user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to analytical data, stored data, display data, etc.) related to this application are information and data for which the user's permission has been obtained or for which sufficient permission has been obtained from each party, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entries are provided for the user to select permission or denial.

[0025] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "said," and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, as used herein, the term "and / or" should be understood to mean and include any and all possible combinations of one or more of the associated listed items.

[0026] In this application, terms such as first, second, and third may be used to describe various pieces of information, but it should be understood that such information is not limited to these terms. These terms are used only to distinguish between pieces of information of the same type. For example, first information may be referred to as second information, and similarly, second information may be referred to as first information, without departing from the scope of this application. Depending on the context, for example, the word "if" used herein may be interpreted as "if," "when," or "in response to determining."

[0027] It should be noted that in other embodiments, the steps of the corresponding method may not necessarily be performed in the order shown and described herein. In some other embodiments, the method may include more or fewer steps than those described herein. In addition, a single step described herein may be decomposed and described as multiple steps in other embodiments, while multiple steps described herein may be combined and described as a single step in other embodiments.

[0028] To solve the technical problem that a terminal device may have difficulty exiting the LPCD mode and thus may have difficulty in performing normal communication, an embodiment of the present application provides an NFC electric field detection system including an NFC antenna and a detection control circuit. The near field communication NFC antenna is used to receive a first radio frequency signal emitted by the terminal device when sensing the NFC radio frequency field of the terminal device. The detection control module is used to detect that the terminal device is in the low power card detection LPCD mode according to the first radio frequency signal, and when emergency communication with the terminal device is to be performed, transmits a second radio frequency signal to the terminal device via the NFC antenna to excite the terminal device to perform communication with the terminal device.

[0029] In an embodiment of the present invention, the NFC antenna receives a first radio frequency signal emitted by the terminal device, and the detection control circuit transmits a second radio frequency signal to excite the terminal device. In this way, when the terminal device is difficult to exit the LPCD mode, the second radio frequency signal to excite the terminal device wakes up the terminal device and puts it into the normal card detection mode so as to communicate with the terminal device. This enables normal communication with the terminal device to be realized and improves the effectiveness of communication.

[0030] The NFC electric field detection system according to the embodiment of the present application may be applied to an NFC device, which operates in a passive mode (hereinafter also referred to as an NFC passive device), and a terminal device that communicates with the NFC device operates in an active mode.

[0031] 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.

[0032] FIG. 1 shows a schematic diagram of the configuration of an NFC electric field detection system 10 according to an embodiment of the present application.

[0033] 1, the NFC electric field detection system 10 includes an NFC antenna 21 (hereinafter referred to as an antenna) and a detection control module 22 connected to the NFC antenna 21. The NFC antenna 21 is used to receive a first radio frequency signal emitted by the terminal device when the NFC radio frequency field of the terminal device is sensed. The first radio frequency signal herein may include, but is not limited to, an NFC signal.

[0034] The detection control module 22 is used to detect that the terminal device is in a low power card detection LPCD mode according to the first radio frequency signal, and when emergency communication with the terminal device is to be performed, sends a second radio frequency signal to the terminal device through the NFC antenna 21 to excite the terminal device so as to communicate with the terminal device.

[0035] The above-mentioned LPCD mode means that when the terminal device detects an NFC slave device, the unlocking will enter low power consumption mode after a certain time interval to save power consumption, and thus the card detection will also enter LPCD mode.

[0036] Meanwhile, the second radio frequency signal is a specific signal for exciting the terminal device. The frequency band range of the specific signal is between 12 MHz and 14 MHz. That is, when the terminal device receives the specific signal for excitation, it wakes up from the LPCD mode and enters the normal card detection mode.

[0037] The normal card detection mode means that the mobile terminal maintains full power card detection for some time after unlocking to improve the speed and success rate of NFC. The LPCD and normal detection modes both use a 13.56MHz sine wave emitted from the terminal device, with only differences in transmission time and amplitude, and couple energy through a coil.

[0038] Since the second radio frequency signal is an excitation signal, it may be a null carrier signal that does not contain any information. This not only reduces the system burden of transmitting signals but also improves information transmission efficiency. For example, the NFC operating frequency band is 13.56 MHz. The second radio frequency signal may be, but is not limited to, a 13.56 MHz null carrier signal. Thus, when the terminal device receives the 13.56 MHz radio frequency signal, it wakes up from the LPCD mode and enters the normal card detection mode.

[0039] Of course, after the detection control module 22 sends the second radio frequency signal to the terminal device through the NFC antenna 21 to excite the terminal device, if the communication status of the terminal device does not return to normal communication, the detection control module 22 can resend the second radio frequency signal to the terminal device through the NFC antenna 21 multiple times until the terminal device is woken up and in normal card detection mode and has normal communication with the terminal device.

[0040] After the detection control module 22 transmits a second radio frequency signal to the terminal device through the NFC antenna 21 to excite the terminal device, when the communication status of the terminal device returns to normal communication, the terminal device can read the predetermined information in the NFC electric field detection system 10. The predetermined information is information that is preset in the NFC device. In this way, the terminal device may read the stored predetermined information to realize communication with the NFC device.

[0041] In some examples, the control circuit 222 is further configured to determine the terminal type of the terminal device according to the transmission period of the electric field of the terminal device when detecting that the terminal device is in the LPCD mode according to the first radio frequency signal and performing emergency communication with the terminal device, and transmit a second radio frequency signal to the terminal device according to the terminal type for exciting the terminal device. In this way, by determining the terminal type, the second radio frequency signal can be emitted according to the terminal type, thereby improving the accuracy and timeliness of the radio frequency signal emission.

[0042] The transmission period of the electric field varies depending on the terminal device, and the terminal type can be distinguished by the transmission period of the electric field. The terminal type in this specification is, for example, but not limited to, terminal devices with different model numbers produced by different manufacturers. For example, the transmission period of the electric field of an iPhone (registered trademark) is generally around 300 ms.

[0043] Furthermore, according to the terminal type, a second radio frequency signal for exciting the terminal type is determined from the correspondence between different terminal types and radio frequency signals used for excitation, and the second radio frequency signal is transmitted to the terminal device.

[0044] In the embodiment of the present invention, the detection control module 22 is introduced to enable the NFC device operating in passive mode to have the ability to detect external signals. After the NFC antenna 21 detects the signals, the NFC device is equipped with a response strategy, such as emitting an excitation field or an operating null carrier wave signal, to guide or complete the communication under poor communication quality conditions.

[0045] FIG. 2 is a schematic diagram showing a specific configuration of the NFC electric field detection system 10 shown in FIG.

[0046] As shown in Fig. 2, the NFC antenna 21 is used to sense the field strength of the NFC radio frequency field when the terminal device 20 emits an NFC signal and form an electrical signal corresponding to the field strength. Furthermore, the NFC antenna 21 has a plurality of signal output terminals. The plurality of signal output terminals shown in Fig. 2 include a signal output terminal A1 and a signal output terminal B1, and electrical signals are output through the plurality of signal output terminals. The NFC antenna 21 can sense whether the field strength of the NFC radio frequency field exists in real time, thereby avoiding leakage and realizing the accuracy of the NFC antenna 21 in sensing the field strength of the NFC radio frequency field.

[0047] Accordingly, the detection control module 22 includes a signal sampling circuit 221 and a control circuit 222 connected to the signal sampling circuit 221. The signal sampling circuit 221 is used to sample an electrical signal. As shown in FIG. 2, 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. Illustratively, the acquisition input terminals include a sampling input terminal A2 and a sampling input terminal B2. In the example shown in FIG. 2, the sampling input terminal B2 is connected to the signal output terminal B1, thereby completing signal acquisition for 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 signal acquisition for the signal output terminal A1 of the antenna. The acquisition input terminals may be connected to either the signal output terminal A1 or the signal output terminal B1.

[0048] 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. In this way, the amplitude signal sampling circuit 221 can sample an amplitude signal, such as a level amplitude. The voltage acquisition circuit or current acquisition circuit may acquire other forms, such as an induced current. For example, the current value may be obtained by level amplitude and resistance. The signal sampling circuit 221 transmits the sampled signal to the control circuit 222.

[0049] The control circuit 222 is used to obtain characteristic information of the NFC radio frequency field of the terminal device 20 according to the numerical value of the electrical signal, and the characteristic information of the NFC radio frequency field is, for example, information about the period at which the terminal device 20 emits the radio frequency field strength, amplitude strength, etc. If the amplitude strength of the characteristic information meets the LPCD mode threshold, it detects that the terminal device 20 is in the LPCD mode, and sends a second radio frequency signal to the terminal device 20 to excite the terminal device 20 when the terminal device 20 does not read data from the NFC electric field detection system 10. The failure to read data from the NFC electric field detection system 10 is used to reflect emergency communication with the terminal device 20.

[0050] The threshold value may be set according to the LPCD mode and the normal card detection mode, but is not limited thereto. For example, when the amplitude intensity of the characteristic information satisfies the threshold value of the LPCD mode, the terminal device 20 may be detected as being in the LPCD mode, including, but not limited to, a level lower than 1 volt. When the amplitude intensity of the characteristic information satisfies the threshold value of the LPCD mode, the terminal device 20 may be detected as being in the normal card detection mode, including, but not limited to, a level higher than 5 volts.

[0051] 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 capacitance, resistors, and capacitors to process signals.

[0052] In the embodiment of the present application, the signal sampling circuit 221 can acquire the desired signal from the antenna, and by combining the detection control module 22 with the above-mentioned NFC antenna 21, the addition of the signal sampling circuit 221 to the detection control module 22 can complete the sensing of the source of the external terminal device 20 that can emit a radio frequency field, which is not provided, and further the detection control module 22 completes the subsequent related strategies.

[0053] In addition to FIG. 2, the NFC antenna 21 may include a plurality of types of NFC antennas 21 as follows.

[0054] 2, the NFC antenna 21 further includes an NFC coil and a grounded noise filter terminal. The NFC antenna 21, which includes the noise filter terminal C1, the signal output terminal A1, and the signal output terminal B1, can also be called a three-terminal antenna.

[0055] The NFC coil is used to sense radio frequency signals, and the noise filter terminal is used to filter noise signals from the radio frequency signals sensed by the NFC coil, so that the NFC antenna 21 receives normal signals other than noise.

[0056] The noise signal may be, but is not limited to, low-frequency noise. In some examples, the noise filter terminal C1 of the NFC antenna 21 is connected to the input terminal C2 of the NFC module 23 and further connected to the single-substrate ground to filter out low-frequency noise received by the antenna, thereby receiving only normal communication signals. In other examples, the noise filter terminal C1 of the NFC antenna 21 is connected to the input terminal C2 of the NFC module 23, and an element such as an inductance capacitor may be connected in series to the link, and further connected to the single-substrate ground to filter out low-frequency noise received by the antenna, thereby receiving only normal communication signals. These normal communication signals are purer than the signals before noise filtering. An antenna using such three terminals receives small, or even no, noise signals, making it easier to perform highly accurate detection.

[0057] The NFC coil includes at least a three-terminal coil, and the noise filter terminal is located at the physical center of the antenna. In this way, the balance between the other signal output terminals can be maintained. Furthermore, the noise filter terminal C1 is located at the physical center of the antenna, thereby maintaining the balance between the signal output terminal A1 and the signal output terminal B1.

[0058] In some embodiments of the at least three-terminal coil, the at least three-terminal coil includes an odd-terminal coil, the noise filter terminal is one noise filter terminal located at the physical center of the NFC antenna 21, and the number of terminals of the odd-terminal coil is equal to or greater than the number of terminals of the three-terminal coil.

[0059] In some other embodiments of the at least three-terminal coil, the at least three-terminal coil includes an even-terminal coil, and accordingly, the noise filter terminals are two noise filter terminals arranged at the physical center of the NFC antenna, and the number of terminals of the even-terminal coil is greater than the number of terminals of the three-terminal coil.

[0060] In the embodiment of the present application, for the three-terminal antenna proposed in the NFC antenna 21, the noise filter terminal C1 of the NFC antenna 21 is connected to the input terminal C2 of the NFC module 23 and connected to the single-substrate ground, which further filters out noise in a certain frequency band, allowing a purer communication signal to be transmitted to the signal sampling circuit 221, allowing the control circuit 222 to make accurate decisions.

[0061] In another embodiment of the NFC antenna 21, the NFC antenna 21 has only two signal output terminals, signal output terminal A1 and signal output terminal B1. In this way, the coil of the NFC antenna 21 is double-ended. When the coil of the NFC antenna 21 senses the NFC signal (13.56 MHz), it also senses other signals, generating noise in the circuit and affecting subsequent sampling. In this solution, the signal output terminal A1 and signal output terminal B1 of the near-field communication NFC antenna 21 are connected to the sampling input terminal B2 and signal output terminal B1 of the NFC module 23, respectively. If the input signal is sufficiently large, the noise may be negligible. This improves the coverage of the NFC antenna 21.

[0062] 2 , the detection control module 22 is used to detect that the terminal device 20 is in a low-power card detection LPCD mode according to the first radio frequency signal, and generates a signal for activating the terminal device 20 when emergency communication is to be performed with the terminal device 20. The NFC electric field detection system 10 further includes an NFC module 23, which is used to receive the signal for activating the terminal device 20, synchronize with the NFC antenna 21, and transmit a modulated second radio frequency signal to the terminal device 20 through the NFC antenna 21. In this way, the NFC module 23 allows the signal generated by the detection control module 22 to be modulated by the NFC module 23 and then emitted through the NFC antenna 21, ensuring the validity of the signal transmission.

[0063] 2, the NFC module 23 and the detection control module 22 may realize two-way communication through a control bus. In addition, the NFC module 23 is further used to demodulate the received radio frequency signal and send the demodulated signal to the control circuit 222.

[0064] Continuing with FIG. 2, the NFC module 23 includes a matching circuit 231 and a modulation / demodulation unit 232 connected to the matching circuit 231. The matching circuit 231 is tuned to the NFC antenna 21 and transmits the matched signal to the modulation / demodulation unit 232. The matched signal may be a tuned signal that has been filtered for electromagnetic interference. The modulation / demodulation unit 232 receives the matched signal and modulates it onto a carrier signal to obtain a second radio frequency signal, which is then transmitted to the NFC antenna 21. The NFC antenna 21 is then used to transmit the second radio frequency signal.

[0065] In some examples, the matching circuit 231 is located after the traces of the signal sampling circuit 221. The matching circuit 231 includes an impedance element used to adjust impedance parameters and resonant frequency parameters, and also an impedance element used to adjust the parasitic influence of the matching circuit 231 on the traces of the signal sampling circuit 221. The impedance element may include, but is not limited to, a variable capacitor, a variable inductance, and a variable resistor. Furthermore, the variable capacitor forms a resonance with the parasitic inductance of the NFC antenna 21 to filter electromagnetic interference. The matching circuit 231 transmits the interference-filtered second radio frequency signal to the modulation / demodulation unit 232. In this way, after the traces of the matching circuit 231 and the traces of the signal sampling circuit 221 are arranged, the impedance parameters of the impedance element are adjusted to change the parasitic influence of the matching circuit 231 on the traces of the signal sampling circuit 221.

[0066] In the embodiment of the present application, the matching circuit 231 is located after the trace of the signal sampling circuit 221, and the impedance parameters of the impedance elements are adjusted to reduce the parasitic influence of the matching circuit 231 on the trace of the signal sampling circuit 221. This can reduce the parasitic influence of the matching circuit 231 on the trace of the signal sampling circuit 221. Furthermore, the parasitic influence of the matching circuit 231 on the trace of the signal sampling circuit 221 is avoided.

[0067] The application scenarios of the NFC electric field detection system 10 of the present application may include, but are not limited to, UnionPay, aggregated payment device manufacturers, and related enterprises that research, develop, and produce NFC devices such as mobile phones.

[0068] 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 FIG. 3, including the following steps 310 to 320.

[0069] Step 310: When sensing the NFC radio frequency field of the terminal device, receive a first radio frequency signal emitted by the terminal device.

[0070] Step 320: According to the first radio frequency signal, if the terminal device is detected to be in a low power consumption card detection LPCD mode and emergency communication is to be performed with the terminal device, send a second radio frequency signal to the terminal device through the NFC antenna to excite the terminal device, so as to communicate with the terminal device.

[0071] In some embodiments, the above step 310 may further include a step in which the NFC antenna senses the field strength of the NFC radio frequency field when the terminal device emits an NFC signal, and forms an electrical signal corresponding to the field strength.

[0072]

[0033] Accordingly, the detection control module includes a signal sampling circuit and a control circuit connected to the signal sampling circuit. The above step 320 may further include the steps of: the signal sampling circuit sampling the electrical signal; the control circuit acquiring characteristic information of the NFC radio frequency field of the terminal device according to the numerical value of the electrical signal; detecting that the terminal device is in the LPCD mode when the amplitude intensity of the characteristic information meets the threshold of the LPCD mode; and transmitting a second radio frequency signal to the terminal device to excite the terminal device when the terminal device has not read data from the NFC electric field detection system.

[0073] In some embodiments, the above step 320 may further include: generating a signal to excite the terminal device when detecting that the terminal device is in a low-power card detection LPCD mode according to the first radio frequency signal and performing emergency communication with the terminal device. The NFC electric field detection method may further include receiving the signal to excite the terminal device, tuning with an NFC antenna, and transmitting a modulated second radio frequency signal to the terminal device through the NFC antenna.

[0074] An embodiment of the present application further provides an NFC device, the NFC device operating in a passive mode, and a terminal device communicating with the NFC device operating in an active mode, the NFC device comprising any one of the above NFC electric field detection systems.

[0075] In an embodiment of the present invention, an NFC device operating in passive mode can not only complete communication passively, but also actively excite the terminal device to wake up the terminal device to perform communication, and the success rate does not need to be completely dependent on the terminal device.

[0076] It should be understood that in the description of this application, terms such as "first," "second," etc. are for descriptive purposes only and cannot be understood to indicate or imply relative importance or the number of technical features depicted. Thus, a feature qualified as "first," "second," etc. may explicitly or implicitly include at least one of that feature. In the description of this application, "plurality" means at least two, e.g., two, three, etc., unless expressly qualified otherwise.

[0077] In this application, unless otherwise expressly defined and limited, the terms "attached," "coupled," "connected," "fixed," etc. should be understood in a broad sense, and for example, unless otherwise expressly limited, may refer to a fixed connection, a detachable connection, or being integrated, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, an internal communication between two elements, or an interactive relationship between two elements. Those skilled in the art can understand the specific meanings of the above terms in this application depending on the specific circumstances.

[0078] Unless otherwise expressly defined and limited, in this application, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact with each other, or that the first and second features are in indirect contact with each other via an intermediate medium. Furthermore, a first feature being "above," "above," and "on the upper surface" of a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature has a greater horizontal height than the second feature. A first feature being "below," "below," and "on the lower surface" of a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature has a smaller horizontal height than the second feature.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combinations of these technical features, they should all be considered within the scope of this specification.

[0080] The above examples merely represent some embodiments of the present application, and although the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art may make some modifications and improvements without departing from the inventive concept of the present application, and all of these fall within the scope of protection of the present application.

Claims

1. a near field communication (NFC) antenna for receiving a first radio frequency signal emitted by a terminal device when the NFC antenna senses an NFC radio frequency field of the terminal device; a detection control module used to detect that the terminal device is in a low power card detection LPCD mode according to the first radio frequency signal, and the detection control module transmits a second radio frequency signal to the terminal device through the NFC antenna to excite the terminal device to communicate with the terminal device when emergency communication is to be performed with the terminal device; NFC electric field detection system.

2. the NFC antenna is used to sense a field strength of the NFC radio frequency field when the terminal device emits an NFC signal, and to form an electrical signal corresponding to the field strength; Accordingly, the detection control module comprises 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 used to obtain characteristic information of the NFC radio frequency field of the terminal device according to the numerical value of the electrical signal, and detects that the terminal device is in the LPCD mode when the amplitude intensity of the characteristic information meets the threshold of the LPCD mode, and sends the second radio frequency signal to the terminal device when the terminal device does not read data of the NFC electric field detection system; The NFC electric field detection system of claim 1 .

3. the NFC antenna further includes an NFC coil and a grounded noise filter terminal; The NFC coil is used to sense radio frequency signals, The noise filter terminal is used to filter noise signals of the radio frequency signals sensed by the NFC coil so that the NFC antenna receives normal signals other than noise. The NFC electric field detection system of claim 2 .

4. the NFC coil includes at least a three-terminal coil, and the noise filter terminal is disposed at the physical center of the antenna; The NFC electric field detection system of claim 3 .

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

6. The detection control module is used to detect that the terminal device is in a low power card detection (LPCD) mode according to the first radio frequency signal, and generates a signal to excite the terminal device when emergency communication is performed with the terminal device; the NFC electric field detection system further comprises an NFC module adapted to receive the signal for exciting the terminal device, and to tune with the NFC antenna and transmit the modulated second radio frequency signal to the terminal device through the NFC antenna; The NFC electric field detection system according to any one of claims 1 to 5.

7. the NFC module includes a matching circuit and a modulation / demodulation unit connected to the matching circuit; the matching circuit is used to tune with the NFC antenna and transmit a matched signal to the modulation / demodulation unit; the modulation / demodulation unit is used for receiving the matched signal, modulating the matched signal onto a carrier signal, and then obtaining the second radio frequency signal, and transmitting the second radio frequency signal to the NFC antenna; the NFC antenna is further used to transmit the second radio frequency signal; The NFC electric field detection system of claim 6 .

8. the matching circuit is after the trace of the signal sampling circuit; the matching circuit comprises an impedance element used to adjust impedance parameters and resonant frequency parameters, and further an impedance element used to adjust parasitic effects of the matching circuit on traces of the signal sampling circuit. The NFC electric field detection system of claim 7 .

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

10. The detection control module is further configured to detect that the terminal device is in the LPCD mode according to the first radio frequency signal, and when performing emergency communication with the terminal device, determine a terminal type of the terminal device according to a transmission period of the electric field of the terminal device, and transmit the second radio frequency signal to the terminal device according to the terminal type. The NFC electric field detection system of claim 1 .

11. receiving a first radio frequency signal emitted by a terminal device when sensing an NFC radio frequency field of the terminal device; detecting that the terminal device is in a low power card detection LPCD mode according to the first radio frequency signal, and when performing emergency communication with the terminal device, sending a second radio frequency signal to the terminal device through an NFC antenna to excite the terminal device to communicate with the terminal device; NFC electric field detection method.

12. An NFC device, the NFC device operating in a passive mode, a terminal device communicating with the NFC device operating in an active mode, the NFC device comprising an NFC electric field detection system according to any one of claims 1 to 10. NFC device.

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