Near field communication nfc device and communication method thereof

Abstract

The application discloses an NFC device and a communication method thereof, and belongs to the technical field of communication. The method comprises a driving circuit, a coil antenna and an NFC driving controller. The driving circuit comprises a first driving module and a second driving module. The first driving module outputs an alternating driving voltage, and the second driving module outputs a direct current driving voltage. The NFC driving controller is connected with the first driving module and the second driving module respectively, and is used for controlling the start or stop of the first driving module and the second driving module. The coil antenna is connected with the first driving module and the second driving module respectively, and is used for generating a high-frequency alternating magnetic field based on the alternating driving voltage and a constant magnetic field based on the direct current driving voltage.

Description

Technical Field

[0001] This application belongs to the field of near field communication, specifically relating to a near field communication (NFC) device and its communication method. Background Technology

[0002] Near Field Communication (NFC) is a near field communication technology based on 13.56MHz. It is a point-to-point near field communication function, mainly used in scenarios such as access control cards, transportation cards, attendance clocking, and ID cards.

[0003] Currently, NFC devices operate in two modes: reader mode and card emulation mode. Generally, NFC devices, including electronic devices with NFC card reading and / or card emulation functions, card readers, and card emulation devices, implement NFC antenna functionality by installing a flexible circuit board coil antenna or an antenna on the top of the casing. However, the location of these antennas varies significantly between different models, and users are often unaware of the NFC antenna location of their specific device. Furthermore, in different scenarios, the shape of the card reader carrier varies, and the reader's location is often inconspicuous, making it difficult for users to accurately locate the card-swiping position and align it with the NFC coil of the NFC device.

[0004] As a near-field communication technology, its transmission power and characteristics weaken as the distance between the two NFC devices increases or they become misaligned. Alignment is required for successful card swiping, and near-field communication will fail if the user does not align the devices. Summary of the Invention

[0005] The purpose of this application is to provide an NFC device and its communication method that can solve the problem of near-field communication failure caused by misalignment of the NFC antenna.

[0006] In a first aspect, embodiments of this application provide a near-field communication (NFC) device, including: a driving circuit, a coil antenna, and an NFC driving controller.

[0007] The driving circuit includes a first driving module and a second driving module, wherein the first driving module outputs an AC driving voltage. ， The second drive module 20 outputs a DC drive voltage;

[0008] The NFC driver controller is connected to the first driver module and the second driver module respectively, and is used to control the activation or deactivation of the first driver module and the second driver module;

[0009] The coil antenna is connected to the first driving module and the second driving module respectively, and is used to generate a high-frequency alternating magnetic field based on the AC driving voltage and to generate a constant magnetic field based on the DC driving voltage.

[0010] Secondly, embodiments of this application provide a communication method for an NFC device, applied to the device as described in the first aspect above, the method comprising:

[0011] When the coil antenna generates a high-frequency alternating magnetic field based on the AC driving voltage output by the first driving module, if an external magnetic field is detected, the second driving module is controlled by the NFC driving controller to start and output the DC driving voltage.

[0012] The coil antenna generates a constant magnetic field based on the DC drive voltage;

[0013] The high-frequency alternating magnetic field is used to perform data transmission and reception between the NFC device and the first NFC device corresponding to the external magnetic field.

[0014] In this embodiment, the coil antenna is driven by the AC drive signal of the first drive module to generate a high-frequency AC magnetic field, and the coil antenna is driven by the DC drive signal of the second drive module to generate a constant magnetic field. This enables two NFC devices to perform near-field communication by generating a magnetic attraction force based on the constant magnetic field between them, which attracts one NFC device to be placed in the optimal sensing area of ​​the other NFC device. This allows the two NFC devices to be accurately and quickly aligned, thus successfully performing near-field communication and improving the working efficiency of card reading or card emulation modes. Attached Figure Description

[0015] Figure 1 This is a structural block diagram of an NFC device according to an embodiment of this application.

[0016] Figure 2 This is a circuit diagram of the NFC device according to the first embodiment of this application.

[0017] Figure 3 This is a schematic diagram illustrating the application scenario of the NFC device according to the first embodiment of this application.

[0018] Figure 4 This is a circuit diagram of an NFC device according to the second embodiment of this application.

[0019] Figure 5 This is a schematic diagram illustrating the application scenario of the NFC device according to the second embodiment of this application.

[0020] Figure 6 This is a circuit diagram of an NFC device according to the third embodiment of this application.

[0021] Figure 7 This is a flowchart of a communication method of an NFC device according to an embodiment of this application.

[0022] Figure 8 This is a flowchart of a communication method for an NFC device according to a specific embodiment of this application.

[0023] Figure 9 This is a flowchart of a communication method for an NFC device according to another specific embodiment of this application.

[0024] Figure 10 This is a structural block diagram of an NFC device according to another embodiment of this application.

[0025] Figure 11 This is a circuit diagram of an NFC device according to the fourth embodiment of this application.

[0026] Figure 12 This is a circuit diagram of an NFC device according to the fifth embodiment of this application.

[0027] Figure 13 This is a flowchart of a communication method for an NFC device according to another embodiment of this application.

[0028] Figure 14 This is a flowchart of a communication method for an NFC device according to a specific embodiment of this application. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0030] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0031] The NFC device and its communication method provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0032] Figure 1 This is a structural block diagram of an NFC device according to an embodiment of this application, combined with... Figure 1 and Figure 3The NFC device 100 of this application embodiment includes: a driving circuit, a coil antenna 50, and an NFC driving controller 30. The driving circuit includes a first driving module 10 and a second driving module 20. The first driving module 10 outputs an AC driving voltage. ， The second driving module 20 outputs a DC driving voltage; the NFC driving controller 30 is connected to the first driving module 10 and the second driving module 20 respectively, and is used to control the activation or deactivation of the first driving module 10 and the second driving module 20; the coil antenna 50 is connected to the first driving module 10 and the second driving module 20 respectively, and is used to generate a high-frequency alternating magnetic field based on the AC driving and a constant magnetic field based on the DC driving voltage.

[0033] In this embodiment, the first driving module 10 and the second driving module 20 are controlled by the NFC driving controller 30 built into the NFC chip (IC) of the NFC device. The NFC IC is a component dedicated to near-field communication. After the NFC driving controller 30 enables the first driving module 10, it generates an AC driving voltage, which is provided to the coil antenna 50 to generate a high-frequency AC magnetic field of 13.56MHz, thereby enabling data transmission and reception between the two NFC devices, namely the card reader device and the card emulation device.

[0034] NFC devices can be electronic devices with NFC peer-to-peer communication capabilities, including card readers, mobile terminals with card reading or card emulation functions, and so on.

[0035] After the NFC driver controller 30 controls the second driver module 20 to be enabled, a DC drive voltage is generated and supplied to the coil antenna 50 to generate a constant magnetic field. The constant magnetic field generated by the NFC device 100 and the NFC device communicating with the other end is based on the principle of attraction between opposite magnetic fields. A magnetic attraction force is generated between the NFC coil antennas of the two NFC devices, namely the card reader device and the card emulator device. The magnetic attraction force attracts one NFC device to be placed in the optimal sensing area of ​​the other NFC device, aligning the two NFC devices.

[0036] In this embodiment, a second driving module capable of outputting DC driving voltage is provided to the NFC coil antenna on an NFC device. When near-field communication is required, the DC driving source is activated, i.e., the second driving module performs DC biasing and generates a constant magnetic field. The magnetic attraction generated by the interaction of the constant magnetic fields of the two NFC devices is used to magnetically align the two NFC devices, enabling successful near-field communication and improving the success rate of card swiping.

[0037] refer to Figure 2Optionally, the second driving module 20 includes a second switching unit TX2. The first terminal of the second switching unit TX2 is connected to a constant voltage VDDPA. The second terminal of the second switching unit TX2 is connected to the NFC driving controller 30. The third terminal of the second switching unit TX2 is connected to either the first terminal or the second terminal of the coil antenna 50 and outputs the DC driving voltage. The NFC driving controller 30 is used to control the conduction and disconnection of the second switching unit TX2. One end of the coil antenna 50 is connected to the third terminal of the second switching unit TX2, and the other end of the coil antenna 50 is grounded through the second inductor L2.

[0038] The second switching unit TX2 is used as a DC drive source to generate a constant current on the coil antenna 50, thereby obtaining a constant magnetic field. This creates a magnetic attraction between the coil antenna and the constant magnetic field generated by another NFC device for external communication, helping to align the NFC sensing areas corresponding to the coil antennas of the two NFC devices.

[0039] In one embodiment, the second switching unit TX2 includes a MOSFET or a transistor. The MOSFET may include a PMOS transistor, an NMOS transistor, or a combination of both. Figure 2 As shown, the second switching unit TX2 is a MOSFET 201.

[0040] The current generated by the DC drive voltage output by the second switching unit TX2 needs a current path. Therefore, as shown by the dotted arrow in the figure, the constant current enters from one end of the coil antenna 50, is transmitted in the circuit formed by the windings of the coil antenna 50, generates a constant magnetic field, and finally is grounded from the other end of the coil antenna 50, forming the required current path.

[0041] However, since the coil antenna 50 itself also receives a 13.56MHz high-frequency signal for NFC communication, directly grounding the other end of the coil antenna 50 would cause signal and power attenuation. Therefore, in one embodiment, the NFC device also includes a second inductor L2, which is disposed between the grounded end of the coil antenna 50 and ground. The second inductor L2 is used to ground the DC current corresponding to the constant magnetic field of the coil antenna 50 and isolate the AC current corresponding to the AC driving voltage that generates the high-frequency alternating magnetic field of the coil antenna 50.

[0042] The second inductor L2 isolates high-frequency AC signals and allows DC signals to pass through, preventing the other end of the coil antenna 50 from being directly grounded, thus avoiding high-frequency signal and power attenuation.

[0043] Combination Figure 2The first driving module includes a first switching unit TX1 and a matching unit: the first terminal of the first switching unit TX1 is connected to a constant voltage VDDPA, the second terminal of the first switching unit TX1 is connected to the NFC driving controller 30, and the third terminal of the first switching unit TX1 is connected to the matching unit, for alternately turning on and off the constant voltage VDDPA and the matching unit to generate the AC driving voltage.

[0044] The NFC driver controller 30 controls the first switching unit TX1 to alternately turn the constant voltage VDDPA on and off with the matching unit, causing the constant voltage VDDPA to be output alternately. The square wave signal of the constant voltage VDDPA is converted by the matching unit to obtain a sinusoidal AC drive voltage, allowing the signal to be transmitted more efficiently. Thus, the AC drive voltage drives the connected coil antenna 50 to oscillate and transmit data, enabling point-to-point NFC communication with the first NFC device 200 at the counterpart of the NFC device 100.

[0045] refer to Figure 2 In this embodiment, the first driving module 10 and the second driving module 20 may reuse some components of the transceiver (TX) differential full-bridge driving circuit built into a conventional NFC IC. The first driving module 10 and the second driving module 20 can be connected to the same constant voltage VDDPA, and both are controlled by the NFC driving controller 30 that controls the TX differential full-bridge driving circuit for startup and shutdown. The constant voltage VDDPA can be obtained by processing the battery voltage VBAT through a DC-DC converter and a low-dropout linear regulator TXLDO, and then provided to both the first driving module 10 and the second driving module 20.

[0046] Below, in conjunction with Figure 2 The circuit structure of an NFC device according to one embodiment of this application is described.

[0047] like Figure 2As shown, the first switching unit TX1 includes a first switching transistor 101 and a second switching transistor 103. The matching unit includes a first inductor L1, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The first terminal of the first switching transistor is connected to the constant voltage VDDPA, the second terminal of the first switching transistor is connected to the NFC driver controller, and the third terminal of the first switching transistor is connected to both the second switching transistor and the first inductor L1. The first terminal of the second switching transistor 103 is connected to the third terminal of the first switching transistor, the second terminal of the second switching transistor is connected to the NFC driver controller, and the third terminal of the second switching transistor is grounded. The first terminal of the first inductor L1 is connected to the third terminal of the first switching transistor. The second terminal of the first inductor is connected to the first capacitor C1 and the fourth capacitor C4 respectively; the first terminal of the first capacitor is connected to the second terminal of the first inductor L1 and the first terminal of the fourth capacitor, and the second terminal of the first capacitor is connected to the second capacitor and the first terminal of the coil antenna; the first terminal of the second capacitor is connected to the second terminal of the first capacitor and the first terminal of the coil antenna, and the second terminal of the second capacitor is connected to the second terminal of the coil antenna and the third capacitor; the first terminal of the third capacitor is connected to the second terminal of the second capacitor and the second terminal of the coil antenna respectively, and the second terminal of the third capacitor is grounded; the first terminal of the fourth capacitor is connected to the second terminal of the first inductor L1, and the second terminal of the fourth capacitor is grounded.

[0048] In one embodiment, the first switching transistor 101 and the second switching transistor 103 of the first switching unit TX1 are respectively a PMOS transistor and an NMOS transistor. The NFC driver controller 30 controls the first switching unit TX1 to output an AC drive voltage by controlling the conduction and closure of the first switching transistor 101 and the second switching transistor 103.

[0049] Specifically, the principle of generating AC drive voltage through the first switching unit TX1 is as follows: During a certain period, the first switching transistor 101 of the first switching unit TX1 is turned on and the second switching transistor 103 of the first switching unit TX1 is turned off, thereby turning on the constant voltage VDDPA and the matching unit. The current corresponding to the constant voltage VDDPA flows through the first inductor L1, into the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 and charges the capacitors. The charging current flows in one direction to the coil antenna 50.

[0050] After each capacitor in the matching unit is fully charged, the first switch 101 of the first switching unit TX1 is turned off, and the second switch 103 of the first switching unit TX1 is turned on, so that each capacitor in the matching unit discharges for a period of time. The discharge current flows from the coil antenna 50 to the second switch 103 and ground in another direction. The two currents are in opposite directions.

[0051] After the capacitor discharge is complete, the above steps are repeated to control the alternating switching of the first switch 101 and the second switch 103, thereby changing the current direction and forming an AC drive signal for the coil antenna 50.

[0052] In this embodiment, the first switching unit TX1 of the NFC device 100 is used as a single-ended AC drive source to generate a 13.56MHz high-frequency AC drive voltage signal, which drives the coil antenna 50 to oscillate and communicate, enabling data transmission and reception between the NFC device 100 and the first NFC device 200. The first switching unit TX2 of the NFC device 100 is used as a DC drive source to generate a DC drive voltage signal, which is used to generate a constant current in the coil antenna 50, resulting in a constant magnetic field. This magnetic field then attracts the NFC device 100 to the constant magnetic field of the external first NFC device 200, aligning the NFC sensing areas of the antennas between the NFC device 100 and the first NFC device 200.

[0053] Figure 3 This is a schematic diagram illustrating an application scenario of an NFC device according to an embodiment of this application. The NFC device 100 and the first NFC device 200 may have the same circuit structure, meaning that in addition to enabling NFC communication between the two devices, both also have the function of generating a constant magnetic field. The NFC device 100 generates a magnetic field in the direction from S polarity to N polarity as shown in the diagram, and the first NFC device 200 generates a magnetic field in the same direction as shown in the diagram. Since the two constant magnetic fields are in the same direction, a magnetic attraction force F is generated, enabling alignment of the NFC sensing areas between the two devices.

[0054] When the NFC device 100 and the first NFC device 200 have the same circuit structure, the NFC driver controller 30 can output an AC drive voltage and generate a high-frequency alternating magnetic field in the coil antenna 50 by controlling the first switching unit TX1 to alternately turn on and off the constant voltage VDDPA and the matching unit. The NFC driver controller 30 can also output a DC drive voltage and generate a constant magnetic field in the coil antenna 50 by controlling the second switching unit TX2.

[0055] NFC device 100 and first NFC device 200 can generate a magnetic attraction force F between them through the above circuit structure. The magnetic attraction force F is used to accurately align with the NFC sensing area and successfully conduct NFC communication.

[0056] In the embodiments of this application, Figure 1The coil antenna 50 shown has only one set of windings, and the design characteristics of this set of windings are optimized for 13.56MHz NFC communication. In the case of a DC drive source for generating a constant magnetic field introduced in this embodiment, the coil antenna 50 can also have other different structural forms to achieve better DC magnetic attraction performance, such as... Figure 4 and Figure 6 As shown.

[0057] exist Figure 4 In this embodiment, the coil antenna 50 includes a first winding 52 and a second winding 54. The first end of the first winding 52 is connected to the second end of the first capacitor C1 and the first end of the second capacitor C2. The second end of the first winding 52 is connected to the second end of the second capacitor C2 and the first end of the third capacitor C3. The first end of the second winding 54 is connected to the third end of the second switching unit TX2. The second end of the second winding 54 is grounded through the second inductor L2.

[0058] refer to Figure 5 The current path of the first winding 52 is as follows: the input is the AC current corresponding to the AC drive voltage of the first drive module 10, and the output is grounded through capacitor C, i.e., the third capacitor C3 of the matching unit. The current path of the second winding 54 (along the direction of the dotted arrow in the figure) is as follows: the input is the constant current corresponding to the DC drive voltage of the second drive module 20, and the output is grounded through inductor L2.

[0059] When the NFC device 100 and the first NFC device 200 have the same circuit structure, the NFC driver controller 30, by controlling the first switching unit TX1 to alternately turn on and off the constant voltage VDDPA and the matching unit, can output an AC drive voltage to one end of the first winding 52, and the voltage flows out from the other end of the first winding 52 and is grounded after coupling through capacitor C. The NFC driver controller 30, by controlling the second switching unit TX2, directly outputs a DC drive voltage to one end of the second winding 54, and the voltage flows out from the other end of the second winding 54 and is grounded after coupling through the second inductor L2.

[0060] NFC device 100 and first NFC device 200 can generate a magnetic attraction force F between them through the above circuit structure. The magnetic attraction force F is used to accurately align with the NFC sensing area and successfully conduct NFC communication.

[0061] In this embodiment, in addition to the first winding 52 that generates a high-frequency alternating magnetic field for NFC communication, the coil antenna 50 also includes a separate second winding 54 for generating magnetic attraction. This second winding 54 directly generates a constant magnetic field based on the DC drive voltage output by the second drive module 20, which improves the magnetic attraction performance of the generated magnetic force. Furthermore, the original NFC coil body of the electronic device can be reused; only the wiring of the second winding 54 needs to be added, resulting in very small increases in cost and space, making mass production feasible.

[0062] Combination Figure 4 In one embodiment, the NFC device further includes a first receiving unit RXP, connected to a first end of the first winding 52, for receiving data transmitted by the first NFC device 200 when communicating with the first NFC device 200.

[0063] Typically, NFC devices include a receiver module connected to both ends of the coil antenna, i.e., the positive and negative terminals, respectively, for example... Figure 2 and Figure 4 The first receiving unit RXP and the second receiving unit RXN are configured such that if only the first receiving module RXP is connected to one end of the coil antenna 50 and the second receiving unit RXN is grounded, then the voltage signal at the positive terminal of the coil antenna 50 can be detected at one end.

[0064] In this embodiment, the first receiving unit RXP is connected to the first end of the first winding 52 to realize single-ended voltage detection of the antenna corresponding to the first winding 52. This connection to the first end of the first winding 52 can include a direct connection between the first receiving unit RXP and the first end of the first winding 52, or an indirect connection via the first capacitor C1. The detected voltage of the first capacitor C1 is the attenuated voltage at the positive terminal of the first winding 52.

[0065] Combination Figure 2 and Figure 4 The voltage detected by the first receiving unit RXP is processed by a series of modules, including bias module B, automatic gain control module AGC, and analog-to-digital conversion module ADC, and then input to the NFC processor 31 inside the NFC device. Based on the detected voltage, the NFC device 100 receives the data sent by the first NFC device 200 during the communication process between the first NFC device 200 and the first NFC device 100.

[0066] exist Figure 6In this embodiment, the coil antenna 50 includes a third winding 53 and a fourth winding 55. The first end of the third winding 53 is grounded through the second inductor L2 and connected to the second end of the first capacitor C1 and the first end of the second capacitor C2. The second end of the third winding 53 is connected to the first end of the fourth winding 55. The first end of the fourth winding 55 is connected to the second end of the second capacitor C2 and the first end of the third capacitor C3. The second end of the fourth winding 55 is connected to the second end of the second switching unit TX2.

[0067] Figure 4 The second winding 54 in this embodiment is only used to generate a constant magnetic field to achieve DC magnetic attraction. To improve the magnetic attraction performance of DC magnetic attraction, a method is proposed... Figure 6 The coil antenna 50 of the embodiment structure. In this embodiment, for example, the coil antenna 50 can be made into a three-tap shape by means of the first contact spring 81, the second contact spring 82 and the third contact spring 83.

[0068] One end of the third winding 53 receives the AC driving voltage output by the first driving module 10 via the first contact spring 81. The other end of the third winding 53 is connected to one end of the fourth winding 55 at point a, that is, the end of the third winding 53 corresponds to the beginning of the fourth winding 55. For example, if the third winding 53 has n coils and the fourth winding 55 has m coils, then the entire coil antenna 50 has (n+m) coils.

[0069] In card reader mode, when the NFC device 100 sends data, it drives the first driving module 10 to output an AC driving voltage. The AC driving voltage can be input through one end of the third winding 53, output through the second contact spring 82 and the third capacitor C3, and generate a high-frequency alternating magnetic field for NFC communication in card reader mode. That is, the n coils of the third winding 53 are used to generate a high-frequency alternating magnetic field.

[0070] In card reading mode, the number of coil windings should be minimized. Therefore, connecting n coils to generate a high-frequency alternating magnetic field can reduce impedance and inductive reactance, thereby improving the working efficiency of NFC card reading.

[0071] When a constant magnetic field is required, the NFC driver controller 30 controls the second switching unit TX2 to start. A constant voltage VDDPA is input to one end of the fourth winding 55 through the third contact spring 83, and flows out from the end of the third winding 53 connected to the first driving module 10, and is grounded after passing through the second inductor L2. That is, a constant magnetic field is generated using (n+m) coils including the third winding 53 and the fourth winding 55.

[0072] A constant magnetic field for magnetic attraction requires a large number of coils to generate a large field strength. Therefore, connecting (n+m) coils to generate a constant magnetic field can improve the magnetic attraction performance and facilitate the quick alignment of two NFC devices for communication.

[0073] Combination Figure 6 In one embodiment, the NFC device further includes a second receiving module, which includes a first receiving unit RXP and a second receiving unit RXN. The first receiving unit RXP is connected to a first end of the third winding 53 and is used to detect a first voltage at the first end of the coil antenna 50. The second receiving unit RXN is connected to a second end of the fourth winding 55 and is used to detect a second voltage at the second end of the coil antenna 50. The second receiving module receives data based on the detected first voltage and second voltage.

[0074] The received data is the data sent by the first NFC device 200 communicating with NFC device 100.

[0075] In this embodiment, the NFC device 100 includes receiving modules respectively connected to both ends of the coil antenna, combined with Figure 6 The receiving module includes a first receiving unit RXP and a second receiving unit RXN, which realizes the voltage signal of the positive and negative terminals of the dual-ended detection coil antenna 50.

[0076] The first receiving unit RXP is connected to one end of the first contact spring 81 corresponding to the third winding 53, and the second receiving unit RXN is connected to one end of the third contact spring 83 corresponding to the fourth winding 54, thereby realizing the dual-terminal voltage detection of the entire coil antenna 50 including (n+m) coils. That is, a high-frequency alternating magnetic field is generated using (n+m) coils including the third winding 53 and the fourth winding 55.

[0077] Combination Figure 6 In card emulation mode, the voltages detected by the first receiving unit RXP and the second receiving unit RXN, after being processed by the bias module B, the automatic gain control module AGC, the analog-to-digital conversion module ADC, etc., are input to the NFC processor 31 inside the NFC device. Based on the detection capacitance, the NFC device 100 receives the data sent by the first NFC device 200 during the communication process between the first NFC device 200 and the first NFC device 100.

[0078] When simulating a card, as many coil windings as possible are needed. Therefore, connecting (n+m) coils to generate a high-frequency alternating magnetic field can enhance mutual inductance and improve the success rate of NFC card swiping.

[0079] In this embodiment, by designing the coil antenna 50 in a three-tap configuration, using a larger number of coil windings in NFC device card reading mode and magnetic attraction generation mode can improve the card swiping success rate and enhance the magnetic attraction. In NFC device card emulation mode, using a smaller number of coil windings can improve the card reading success rate. Furthermore, the original NFC coil body of the electronic device can be reused, requiring only the addition of wiring for the corresponding number of coils, resulting in very small increases in cost and space, making mass production feasible.

[0080] Based on the above-described NFC device structure, this application embodiment also provides a communication method for the NFC device, applied to the above-described... Figures 1 to 6 The NFC device of the embodiment, such as Figure 7 As shown, the method includes:

[0081] S202, when an external magnetic field is detected, the NFC driver controller controls the second driving module to start and output the DC driving voltage;

[0082] S204, the coil antenna generates a constant magnetic field based on the DC drive voltage;

[0083] S206, the NFC device performs data transmission and reception between itself and the first NFC device corresponding to the external magnetic field by means of the high-frequency alternating magnetic field generated by the coil antenna based on the AC driving voltage output by the first driving module.

[0084] In one embodiment of this application, the first driving module 10 and the second driving module 20 can be in a normally open / normally active state. Thus, in card reading or card emulation mode, the magnetic force generated by the second driving module 20 can guide the user to quickly align the NFC device with the NFC communication sensing area of ​​the peer device. However, a normally open second driving module 20 can cause power consumption, heat generation, and magnetic interference issues for the electronic device.

[0085] Therefore, in the above embodiment, the above problem can be solved by starting the second driving module 20 in S202 after detecting a partial magnetic field but before NFC officially starts working. Here, the external magnetic field is the magnetic field generated by the peer device capable of performing NFC communication, including a constant magnetic field or a high-frequency alternating magnetic field.

[0086] In one embodiment, the presence of an external magnetic field can be detected using the existing Hall effect sensor in the electronic device. A detailed flowchart is shown below. Figure 8 As shown, it includes the following steps:

[0087] S302, detect the magnetic field using Hall IC (Hall sensor). If it is detected, proceed to step S304; otherwise, proceed to step S306.

[0088] S304, notify the drive controller 30 to turn on the second switch unit TX2 to start the second drive module 20;

[0089] S306, Keep the second switch unit TX2 closed;

[0090] S308, after the second driving module 20 is activated, the NFC device 100 generates a directional constant magnetic field;

[0091] S310 uses the magnetic attraction force generated by a constant magnetic field to align with the NFC sensing area;

[0092] S312, NFC device 100 begins communication;

[0093] S314, communication completed, away from the magnetic field;

[0094] S316, after detecting a weakening of the magnetic field, notifies the drive controller 30 to shut down the second switch unit TX2.

[0095] When the electronic device itself has a Hall sensor, this embodiment can reuse the Hall sensor to solve the alignment problem caused by the late magnetic attraction of the second switch unit TX2 under the normal operating logic of the NFC device. In addition, by using the Hall sensor to detect the presence of an external magnetic field before turning on the second switch unit TX2, compared with the normally open solution of the second switch unit TX2, it is beneficial to reduce the overall power consumption, increase the user's usage time, and reduce the overall heat generation of the device.

[0096] Hall sensors can be used to detect the presence or absence of magnetic fields. In some cases, the external magnetic field detected by the Hall sensor may not be the high-frequency alternating magnetic field that the NFC device operates in. If the presence of an external magnetic field is detected and the second driving module 20 is activated, it will lead to false triggering of NFC.

[0097] In one embodiment, when an external magnetic field is detected, controlling the second driving module to start and output the DC driving voltage via the NFC driving controller includes: when the frequency of the detected external magnetic field is the same as the frequency of the high-frequency alternating magnetic field, controlling the second driving module to start and output the DC driving voltage.

[0098] In other words, the second drive module 20 is only activated when the detected external magnetic field is a high-frequency alternating magnetic field that the NFC device operates in.

[0099] Since some models do not have electronic devices equipped with Hall sensors, or although they are equipped with Hall sensors, they can only detect the presence or absence of magnetic fields, adding a Hall sensor just to control the on / off timing of the second switching unit TX2 of the NFC device would be costly and could also lead to accidental touches.

[0100] To improve the efficiency of NFC communication, in another embodiment, the first receiving module or the second receiving module of the NFC device 100 can be used to detect the frequency of the external magnetic field. As mentioned above, the first receiving unit RXP and the second receiving unit RXN can detect the voltage at both ends of the coil antenna, and the NFC processor 31 can obtain the frequency of the external magnetic field by detecting the voltage.

[0101] The detailed flowchart is as follows: Figure 9 As shown, it includes the following steps:

[0102] S402, the NFC processor 31 detects whether the external magnetic field is a 13.56MHz magnetic field used for NFC communication through the first receiving unit RXP and the second receiving unit RXN. If it is, proceed to step S404; otherwise, proceed to step S406.

[0103] S404, triggers the generation of an NFC high-frequency alternating magnetic field on event;

[0104] S406, Keep the second switch unit TX2 closed;

[0105] S408, notify NFC driver controller 30 to turn on second switch unit TX2 to start second driver module 20;

[0106] S410, after the second driving module 20 is activated, the NFC device 100 generates a directional constant magnetic field;

[0107] S412 aligns with the NFC sensing area using the magnetic attraction force generated by a constant magnetic field;

[0108] S414, NFC device 100 begins communication;

[0109] S416, communication completed, away from the magnetic field;

[0110] S418, after the NFC processor 31 detects a weakening magnetic field, it notifies the drive controller 30 to turn off the second switch unit TX2;

[0111] S420 triggers the NFC high-frequency alternating magnetic field off event (field off).

[0112] NFC device field strength detection is a technology that detects the strength of NFC signals. It can determine the distance and interaction status between NFC devices by measuring the electromagnetic field strength transmitted between them.

[0113] Using the magnetic field detection function built into the NFC device 100, after detecting the presence of an external 13.56MHz magnetic field, the system is notified to start the second drive module to generate a DC drive voltage, so that the NFC device 100 generates a constant magnetic field, which in turn generates a magnetic attraction with the constant magnetic field of the external device, helping the user to align with the NFC sensing area.

[0114] In addition, the NFC device 100's own magnetic field detection function will only be activated when it detects a 13.56MHz magnetic field dedicated to NFC, which can be used to avoid the problem of NFC communication being triggered erroneously.

[0115] As mentioned above, the second driving module is used as a DC driving source to drive the coil antenna to generate a magnetic field with a constant direction, and to conduct NFC communication with the device on the other end that also has a constant magnetic field.

[0116] Since different external NFC devices may generate constant magnetic fields in different directions, for two NFC devices to achieve magnetic attraction, the directions of their respective constant magnetic fields must be the same. Therefore, NFC devices need to have the ability to adjust the direction of their own magnetic fields. For this, refer to... Figure 10 and Figure 11 In one embodiment, the NFC device further includes a switching module 60, which is connected to the first driving module 10 and the second driving module 20 respectively, for switching the DC driving voltage output by the first driving module 10 and the AC driving voltage output by the second driving module 20.

[0117] refer to Figure 10 A switching module 60 is disposed between the coil antenna 50 and the first driving module 10 and the second driving module 20. When the first driving module 10 outputs an AC driving voltage, the switching module 60 can switch the output of the second driving module 20 to a DC driving voltage, so that the coil antenna 50 generates a constant magnetic field in a first direction. When the second driving module 20 outputs an AC driving voltage, the switching module 60 can switch the output of the first driving module 10 to a DC driving voltage, so that the coil antenna 50 generates a constant magnetic field in a second direction, which is the same as the first direction.

[0118] In this embodiment, both the first driving module 10 and the second driving module 20 have the function of driving the coil antenna 50 to generate a high-frequency alternating magnetic field, and both also have the function of generating a constant magnetic field. Therefore, the switching module 60 reverses the direction of the constant magnetic field generated by the coil antenna 60 to match the direction of the constant magnetic field of the peer NFC device. Thus, while performing communication, the two NFC devices generate magnetic attraction through the constant magnetic field in the same direction, quickly aligning with the NFC sensing area.

[0119] refer to Figure 11The switching module 60 includes a first single-pole double-throw switch 61 and a second single-pole double-throw switch 62; the driving circuit is a differential full-bridge driving circuit, including the first driving module 10 and the second driving module 20.

[0120] The first driving module 10 includes a first switching unit TX1 and a first matching unit. The first terminal of the first switching unit TX1 is connected to a first constant voltage. The second terminal of the first switching unit TX1 is connected to the NFC driving controller 30. The third terminal of the first switching unit TX1 is connected to the first matching unit. The first constant voltage and the first matching unit are alternately turned on and off to generate a first AC driving voltage.

[0121] The second driving module 20 includes: a second switching unit TX2 and a second matching unit. The first terminal of the second switching unit TX2 is connected to a second constant voltage. The second terminal of the second switching unit TX2 is connected to the NFC driving controller 30. The third terminal of the second switching unit TX2 is connected to the second matching unit. It is used to alternately turn on and off the second constant voltage and the second matching unit to generate a second AC driving voltage.

[0122] The moving end of the first single-pole double-throw switch 61 is connected to the first switch unit TX1, and the fixed end of the first single-pole double-throw switch 61 can be connected to the first end of the first matching unit and the second end of the coil antenna 50. The second end of the first matching unit is connected to the first end of the coil antenna 50. The moving end of the second single-pole double-throw switch 62 is connected to the second switch unit TX2, and the fixed end of the second single-pole double-throw switch 62 can be connected to the first end of the second matching unit and the first end of the coil antenna 50. The second end of the second matching unit is connected to the second end of the coil antenna 50.

[0123] The first constant voltage connected to the first terminal of the first switching unit TX1 and the second constant voltage connected to the first terminal of the second switching unit TX2 can be the same or different. (Reference) Figure 11 The first constant voltage and the second constant voltage are the same, both being constant voltage VDDPA.

[0124] When the moving end of the first single-pole double-throw switch 61 is connected to a fixed end connected to the coil antenna 50, the first switching unit TX1 can directly provide the DC drive voltage output based on the constant voltage VDDPA to the coil antenna 50 to generate a constant magnetic field.

[0125] When the moving end of the first single-pole double-throw switch 61 is connected to the other fixed end connected to the first matching unit, the NFC driving controller 30 controls the first switching unit TX1 to alternately turn on and off the constant voltage VDDPA and the first matching unit, so that the first driving module 10 outputs an AC driving voltage based on the constant voltage VDDPA and provides it to the coil antenna 50 to generate an alternating magnetic field.

[0126] When the moving end of the second single-pole double-throw switch 62 is connected to a fixed end connected to the coil antenna 50, the second switching unit TX1 can directly provide the DC drive voltage output based on the constant voltage VDDPA to the coil antenna 50 to generate a constant magnetic field.

[0127] When the moving end of the second single-pole double-throw switch 62 is connected to the other fixed end connected to the second matching unit, the NFC drive controller 30 controls the second switch unit TX2 to alternately turn on and off the constant voltage VDDPA and the second matching unit, so that the second drive module 20 outputs an AC drive voltage based on the constant voltage VDDPA, which is provided to the coil antenna 50 to generate an alternating magnetic field.

[0128] refer to Figure 11The first switching unit TX1 includes a first switching transistor 101 and a second switching transistor 103. The first matching unit includes a third inductor L21, a fifth capacitor C11, a sixth capacitor C12, and a seventh capacitor C13. The first terminal of the first switching transistor 101 is connected to the first constant voltage VDDPA. The second terminal of the first switching transistor 101 is connected to the NFC driver controller 30. The third terminal of the first switching transistor 101 is connected to the second switching transistor 103 and the moving terminal of the first single-pole double-throw switch 61. The first terminal of the second switching transistor 103 is connected to the third terminal of the first switching transistor 101 and the moving terminal of the first single-pole double-throw switch 61. The second terminal of the second switching transistor 103 is connected to the NFC driver controller 30, and the third terminal of the second switching transistor 103 is grounded. The first terminal of the third inductor L21 is connected to the first fixed terminal of the first single-pole double-throw switch 61. The second terminal of the third inductor is connected to the fifth capacitor C11 and the sixth capacitor C12, respectively, and the second terminal of the fifth capacitor C11 is grounded; the first terminal of the sixth capacitor C12 is connected to the second terminal of the third inductor L21 and the first terminal of the fifth capacitor C11, respectively, and the second terminal of the sixth capacitor C12 is connected to the seventh capacitor C13 and the second single-pole double-throw switch 62, respectively; the first terminal of the seventh capacitor C13 is connected to the second terminal of the sixth capacitor C12 and the first terminal of the coil antenna 50, and the second terminal of the seventh capacitor C13 is grounded; wherein, the NFC driver controller 30 is used to control the conduction and disconnection of the first switch tube 101 and the second switch tube 103, the first fixed terminal of the second single-pole double-throw switch is connected to the first terminal of the coil antenna 50, and the second fixed terminal of the first single-pole double-throw switch is connected to the second terminal of the coil antenna 50.

[0129] Combination Figure 11 The second switching unit TX2 includes a third switching transistor 203 and a fourth switching transistor 205, and the second matching unit includes a fourth inductor L22, an eighth capacitor C21, a ninth capacitor C22 and a tenth capacitor C23.

[0130] The first terminal of the third switch 203 is connected to a constant voltage VDDPA, the second terminal of the third switch 203 is connected to the NFC driver controller 30, and the third terminal of the third switch 203 is connected to the moving terminal of the fourth switch 205 and the second single-pole double-throw switch 62, respectively.

[0131] The first end of the fourth switch 205 is connected to the third end of the third switch 203 and the moving end of the second single-pole double-throw switch 62, the second end of the fourth switch 205 is connected to the NFC driver controller 30, and the third end of the fourth switch 205 is grounded.

[0132] The first end of the fourth inductor L22 is connected to the first fixed end of the second single-pole double-throw switch 62. The second end of the fourth inductor L22 is connected to the eighth capacitor C21 and the ninth capacitor C22 respectively. The second end of the eighth capacitor C21 is grounded. The first end of the ninth capacitor C22 is connected to the second end of the fourth inductor L22 and the first end of the eighth capacitor C21 respectively. The second end of the ninth capacitor C22 is connected to the tenth capacitor C23. The first end of the tenth capacitor C23 is connected to the second end of the ninth capacitor C22 and the second end of the coil antenna 50 respectively. The second end of the tenth capacitor C23 is grounded.

[0133] The NFC driver controller 30 is also used to control the on and off states of the third switch 203 and the fourth switch 205.

[0134] In the above embodiments, the first driving module 10 and the second driving module 20 have symmetrical circuit structures, together forming a differential full-bridge driving circuit, which alternately outputs AC driving voltage. Furthermore, while one driving module outputs AC driving voltage, the other driving module outputs DC driving voltage.

[0135] The principle of the AC drive voltage output by the first drive module 10 and the second drive module 20 can be referred to the above regarding... Figure 2 The principle of how the first switching unit TX1 generates AC drive voltage will not be elaborated here.

[0136] A single-pole double-throw switch allows the first switching unit TX1 and the second switching unit TX2 to switch between AC and DC driving sources, generating constant magnetic fields in opposite directions. This enables the NFC device to adjust the direction of its own constant magnetic field. Based on the direction of the external constant magnetic field, either the first switching unit TX1 or the second switching unit TX2 can be activated to output a DC driving voltage to the coil antenna 50, causing the coil antenna 50 to generate a DC driving voltage in the same direction as the external constant magnetic field. This creates a magnetic attraction force, enabling rapid alignment of the NFC sensing areas during communication between two NFC devices.

[0137] Combination Figure 12 In one embodiment, the coil antenna 50 includes a third winding 53 and a fourth winding 55, and the NFC device further includes a third single-pole double-throw switch 63.

[0138] The first end of the third winding 53 is connected to the first fixed end of the third single-pole double-throw switch 63, and is connected to the second end of the sixth capacitor C12 and the first end of the seventh capacitor C13. The second end of the third winding 53 is connected to the first end of the fourth winding 55.

[0139] The first end of the fourth winding 55 is connected to the second end of the ninth capacitor C22 and the first end of the tenth capacitor C23. The second end of the fourth winding 55 is connected to the second fixed end of the third single-pole double-throw switch 63 and to the second end of the fourth switch unit TX4. The moving end of the third single-pole double-throw switch 63 is grounded through the second inductor L2.

[0140] In this embodiment, the coil antenna 50 has Figure 6 The three-tap configuration of the embodiment, and the structure of the third winding 53 and the fourth winding 55 can be referred to Figure 6 Examples are not described here.

[0141] When the moving end of the first single-pole double-throw switch 61 is connected to a fixed end that is connected to one end of the fourth winding 55 via the third contact spring 83, the DC drive voltage output by the first switching unit TX1 based on the constant voltage VDDPA can be directly provided to one end of the fourth winding 55, forming a current path through the fourth winding 55, the third winding 53, a fixed end of the third single-pole double-throw switch 63, and the ground of the second inductor L2, and generating a constant magnetic field.

[0142] When the moving end of the second single-pole double-throw switch 62 is connected to a fixed end that is connected to one end of the third winding 53 via the first contact spring 81, the DC drive voltage output by the second switching unit TX2 based on the constant voltage VDDPA can be directly provided to one end of the third winding 53, forming a current path through the third winding 53, the fourth winding 55, the other fixed end of the third single-pole double-throw switch 63, and the ground of the second inductor L2, and generating a constant magnetic field.

[0143] When a constant magnetic field is required, a coil including the third winding 53 and the fourth winding 55 can be used to generate it. Therefore, using a larger number of coil windings to generate a constant magnetic field can improve magnetic attraction performance and facilitate quick alignment of two NFC devices.

[0144] When the moving end of the first single-pole double-throw switch 61 is connected to the other fixed end connected to the first EMC inductor L21, the NFC drive controller 30 controls the first switch unit TX1 to alternately turn on and off the constant voltage VDDPA and the first matching unit, so that the first drive module 10 outputs an AC drive voltage based on the constant voltage VDDPA and through the third switch unit TX3, the third inductor L21, the sixth capacitor C12, and the first contact spring 81, which is provided to one end of the third winding 53, and forms a current path for the corresponding AC current to be grounded through the other end of the third winding 53 at point a, the second contact spring 82, and the tenth capacitor C23, and generates an alternating magnetic field.

[0145] When the moving end of the second single-pole double-throw switch 62 is connected to the other fixed end connected to the fourth inductor L22, the NFC drive controller 30 controls the second switch unit TX2 to alternately turn on and off the constant voltage VDDPA and the second matching unit, so that the first drive module 10 provides the constant voltage VDDPA to one end of the third winding 53 corresponding to point a through the second switch unit TX4, the fourth inductor L22, the ninth capacitor C22, and the second contact spring 82, and forms a current path for the corresponding alternating current to be grounded through the other end of the third winding 53, the first contact spring 81, and the seventh capacitor C13, and generates an alternating magnetic field.

[0146] In card reading mode, when an alternating magnetic field is required, a coil consisting only of the third winding 53 can be used to generate the alternating magnetic field. Therefore, using a smaller number of coil windings to generate a high-frequency alternating magnetic field in card reading mode can reduce impedance and inductive reactance, thereby improving the efficiency of NFC card reading.

[0147] Combination Figure 12 In one embodiment, the NFC device further includes a third receiving module, which includes a first receiving unit RXP and a second receiving unit RXN. The first receiving unit RXP is connected to a first end of the third winding 53 and is used to detect a third voltage at the first end of the coil antenna 50. The second receiving unit RXN is connected to a second end of the fourth winding 55 and is used to detect a fourth voltage at the second end of the coil antenna 50. The third receiving module receives data based on the third voltage and the fourth voltage.

[0148] The received data is the data sent by the first NFC device 200 communicating with NFC device 100.

[0149] In this embodiment, the first receiving unit RXP is connected to one end of the first contact spring 81 corresponding to the third winding 53, and the second receiving unit RXN is connected to one end of the third contact spring 83 corresponding to the fourth winding 54, thereby realizing the dual-terminal voltage detection of the entire coil antenna 50. That is, a high-frequency alternating magnetic field is generated using a coil including the third winding 53 and the fourth winding 55.

[0150] This high-frequency alternating magnetic field is used for the card emulation mode of NFP devices, combined with Figure 12 The voltages detected by the first receiving unit RXP and the second receiving unit RXN, after being processed by the bias module B, the automatic gain control module AGC, the analog-to-digital conversion module ADC, etc., are input into the NFC processor 31 inside the NFC device. Based on the detection capacitance, the NFC device receives the data sent by the peer NFC device during the communication process between the NFC device and the peer NFC device.

[0151] Card emulation requires as many coil windings as possible. Therefore, connecting more coil windings to generate a high-frequency alternating magnetic field can enhance mutual inductance and improve the success rate of NFC card swiping.

[0152] In this embodiment, by designing the coil antenna 50 in a three-tap configuration, using a larger number of coil windings in NFC device card reading mode and magnetic attraction generation mode can improve the card swiping success rate and enhance the magnetic attraction. In NFC device card emulation mode, using a smaller number of coil windings can improve the card reading success rate. Furthermore, the original NFC coil body of the electronic device can be reused, requiring only the addition of wiring for the corresponding number of coils, resulting in very small increases in cost and space, making mass production feasible.

[0153] In the NFC device based on the above structure, both the first driving module 10 and the second driving module 20 can output a DC driving voltage. In this embodiment, the NFC device performs... Figure 7 In the communication method of the NFC device shown, before controlling the second driving module to start and output the DC driving voltage by the NFC driving controller 30, the method further includes: determining a first direction of the external magnetic field; determining a target driving module in the first driving module 10 and the second driving module 20, wherein the DC driving voltage output by the target driving module makes the second direction of the constant magnetic field generated by the coil antenna 50 the same as the first direction; and controlling the target driving module to start and output the DC driving voltage by the NFC driving controller.

[0154] Specifically, such as Figure 13 As shown, the method includes:

[0155] S502, upon detecting an external magnetic field, determine a first direction of the external magnetic field;

[0156] S504, determine the target driving module in the first driving module and the second driving module, the DC driving voltage output by the target driving module makes the second direction of the constant magnetic field generated by the coil antenna 50 the same as the first direction;

[0157] S506, The target driving module is started by the NFC driving controller to output the DC driving voltage;

[0158] S508, the coil antenna generates a constant magnetic field based on the DC drive voltage;

[0159] S510, the NFC device performs data transmission and reception between itself and the first NFC device corresponding to the external magnetic field by means of the high-frequency alternating magnetic field generated by the coil antenna based on the AC driving voltage output by the first driving module.

[0160] Since different external NFC devices may generate constant magnetic fields in different directions, the directions of their respective constant magnetic fields must be the same in order to achieve magnetic attraction between two NFC devices. Therefore, NFC devices need to have the function of adjusting their own magnetic field direction. When both the first driving module 10 and the second driving module 20 can be used as DC driving sources, only the driving module in the first driving module 10 and the second driving module 20 that controls the direction of the constant magnetic field generated by the coil antenna 50 to be the same as the direction of the external constant magnetic field is activated.

[0161] In this embodiment, the direction of an external constant magnetic field can be detected by an electronic compass, and the corresponding DC drive source can be activated according to the direction of the external constant magnetic field to drive the coil antenna to generate a constant magnetic field with the same direction as the external constant magnetic field.

[0162] The detailed flowchart is as follows: Figure 14 As shown, it includes the following steps:

[0163] S602, determine whether a magnetic field is detected; this can be done through the magnetic field detection function of NFC itself, or through a Hall sensor; if yes, proceed to step S604, otherwise proceed to step S606.

[0164] S604, use an electronic compass to determine whether the direction of the magnetic field near NFC is the N pole, that is, determine the direction of the external constant magnetic field. If it is, proceed to step 608; otherwise, proceed to step 610.

[0165] S606, keep the second switching unit TX2 closed;

[0166] S608, notify the drive controller 30 to turn on the second switch unit TX2 to start the second drive module 20 as a DC drive source to output DC drive voltage;

[0167] S610, notify NFC driver controller 30 to turn on first switch unit TX1 to start first driver module 12 as DC drive source to output DC drive voltage;

[0168] S612, after the second driving module 20 is activated, the NFC device 100 generates a constant magnetic field from the S polarity to the N polarity direction, i.e., the S polarity.

[0169] S614, after the first driving module 10 is started, the NFC device 100 generates a constant magnetic field from the N polarity to the S polarity direction, that is, the N polarity.

[0170] S616 uses the magnetic attraction force generated by a constant magnetic field to align with the NFC sensing area;

[0171] S618, NFC device 100 starts communicating;

[0172] S620, communication completed, away from the magnetic field;

[0173] S622, after detecting a weakening of the magnetic field, notifies the NFC driver controller 30 to turn off the second switch unit TX2 or the first switch unit TX1 to stop generating a constant magnetic field.

[0174] When an external NFC device generates a constant magnetic field in different directions, the direction of the constant magnetic field generated by the NFC device itself can be adjusted by detecting the direction of the external constant magnetic field. This magnetic attraction function enables NFC functionality, helping users quickly and accurately locate the NFC sensing area for card swiping / reading, improving NFC communication success rate and user experience.

[0175] In addition, for NFC charging scenarios, magnetic charging can be achieved, avoiding the inconvenience caused by users holding the device close to the charger for extended periods.

[0176] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0177] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0178] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A near field communication (NFC) device, characterized in that, The application relates to a drive circuit, a coil antenna and an NFC drive controller. The drive circuit comprises a first drive module and a second drive module, the first drive module outputs an alternating current drive voltage, and the second drive module outputs a direct current drive voltage. The NFC drive controller is connected with the first drive module and the second drive module respectively, and is used for controlling the start or stop of the first drive module and the second drive module. The coil antenna is connected with the first drive module and the second drive module respectively, and is used for generating a high-frequency alternating magnetic field based on the alternating current drive voltage and generating a constant magnetic field based on the direct current drive voltage. The second drive module comprises a second switch unit, a first end of the second switch unit is connected with a constant voltage, a second end of the second switch unit is connected with the NFC drive controller, and a third end of the second switch unit is connected with any one of a first end and a second end of the coil antenna and outputs the direct current drive voltage.

2. The apparatus of claim 1, wherein, The NFC drive controller is used for controlling the conduction and disconnection of the second switch unit, one end of the coil antenna is connected with the third end of the second switch unit, and the other end of the coil antenna is grounded through a second inductor. The second switch unit comprises a MOS tube or a triode.

3. The apparatus of claim 2, wherein, The first drive module comprises a first switch unit and a matching unit.

4. The apparatus of claim 1, wherein, A first end of the first switch unit is connected with the constant voltage, a second end of the first switch unit is connected with the NFC drive controller, and a third end of the first switch unit is connected with the matching unit and is used for alternately conducting and disconnecting the constant voltage and the matching unit to generate the alternating current drive voltage. The first switch unit comprises a first switch tube and a second switch tube, and the matching unit comprises a first inductor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor.

5. The apparatus of claim 4, wherein, A first end of the first switch tube is connected with the constant voltage, a second end of the first switch tube is connected with the drive controller, and a third end of the first switch tube is connected with the second switch tube and the first inductor respectively. A first end of the second switch tube is connected with the third end of the first switch tube, a second end of the second switch tube is connected with the NFC drive controller, and a third end of the second switch tube is grounded. A first end of the first inductor is connected with the third end of the first switch tube, and a second end of the first inductor is connected with the first capacitor and the fourth capacitor respectively. A first end of the first capacitor is connected with the second end of the first inductor and the first end of the fourth capacitor, and a second end of the first capacitor is connected with the second capacitor and the first end of the coil antenna. A first end of the second capacitor is connected with the second end of the first capacitor and the first end of the coil antenna, and a second end of the second capacitor is connected with the second end of the coil antenna and the third capacitor. A first end of the third capacitor is connected with the second end of the second capacitor and the second end of the coil antenna respectively, and a second end of the third capacitor is grounded. A first end of the fourth capacitor is connected with the second end of the first inductor, and a second end of the fourth capacitor is grounded. ​ 6. The apparatus of claim 5, wherein, The coil antenna comprises a first winding and a second winding, the second driving module comprises a second switch unit, a first end of the second switch unit is connected to a constant voltage, a second end of the second switch unit is connected to the NFC driving controller, and a third end of the second switch unit is connected to any one of a first end and a second end of the coil antenna and outputs the direct current driving voltage; a first end of the first winding is connected to a second end of the first capacitor and a first end of the second capacitor, and a second end of the first winding is connected to a second end of the second capacitor and a first end of the third capacitor; a first end of the second winding is connected to the third end of the second switch unit, and a second end of the second winding is grounded through the second inductor.

7. The apparatus of claim 5, wherein, The coil antenna comprises a third winding and a fourth winding, the second driving module comprises a second switch unit, a first end of the second switch unit is connected to a constant voltage, a second end of the second switch unit is connected to the NFC driving controller, and a third end of the second switch unit is connected to any one of a first end and a second end of the coil antenna and outputs the direct current driving voltage; a first end of the third winding is grounded through the second inductor and is connected to a second end of the first capacitor and a first end of the second capacitor, and a second end of the third winding is connected to a first end of the fourth winding; a first end of the fourth winding is connected to a second end of the second capacitor and a first end of the third capacitor, and a second end of the fourth winding is connected to the second end of the second switch unit.

8. The apparatus of claim 7, wherein, The second receiving module comprises a first receiving unit and a second receiving unit, the first receiving unit is connected to the first end of the third winding and is configured to detect a first voltage of the first end of the coil antenna; the second receiving unit is connected to the second end of the fourth winding and is configured to detect a second voltage of the second end of the coil antenna; the second receiving module receives data based on the detected first voltage and second voltage.

9. The apparatus of claim 1, wherein, Further comprising: a switching module connected to the first driving module and the second driving module respectively, configured to switch the first driving module to output the direct current driving voltage and the second driving module to output the alternating current driving voltage.

10. The device of claim 9, wherein the switching module comprises a first single-pole double-throw switch and a second single-pole double-throw switch; the driving circuit is a differential full-bridge driving circuit comprising the first driving module and the second driving module; the first driving module comprises a first switch unit TX1 and a first matching unit, a first end of the first switch unit is connected to a first constant voltage, a second end of the first switch unit is connected to the NFC driving controller, and a third end of the first switch unit is connected to the first matching unit, configured to alternately turn on and off the first constant voltage and the first matching unit to generate a first alternating current driving voltage; The second driving module comprises a second switch unit and a second matching unit, a first end of the second switch unit is connected to a second constant voltage, a second end of the second switch unit is connected to the NFC driving controller, a third end of the second switch unit is connected to the second matching unit, and the second constant voltage and the second matching unit are alternately turned on and turned off to generate a second alternating current driving voltage; a moving end of the first single-pole double-throw switch is connected to the first switch unit, and a fixed end of the first single-pole double-throw switch is connected to a first end of the first matching unit, a second end of the coil antenna, a second end of the first matching unit and a first end of the coil antenna; a moving end of the second single-pole double-throw switch is connected to the second switch unit, and a fixed end of the second single-pole double-throw switch is connected to a first end of the second matching unit, a first end of the coil antenna, and a second end of the second matching unit is connected to a second end of the coil antenna.

11. The device of claim 10, wherein the first switch unit comprises a first switch tube and a second switch tube, and the first matching unit comprises a third inductor, a fifth capacitor, a sixth capacitor and a seventh capacitor; a first end of the first switch tube is connected to the first constant voltage, a second end of the first switch tube is connected to the NFC driving controller, and a third end of the first switch tube is connected to the second switch tube and a moving end of the first single-pole double-throw switch; a first end of the second switch tube is connected to the third end of the first switch tube and the moving end of the first single-pole double-throw switch, a second end of the second switch tube is connected to the NFC driving controller, and a third end of the second switch tube is grounded; a first end of the third inductor is connected to a first fixed end of the first single-pole double-throw switch, a second end of the third inductor is connected to the fifth capacitor and the sixth capacitor, and a second end of the fifth capacitor is grounded; a first end of the sixth capacitor is connected to the second end of the third inductor and the first end of the fifth capacitor, and a second end of the sixth capacitor is connected to the seventh capacitor and the second single-pole double-throw switch; a first end of the seventh capacitor is connected to the second end of the sixth capacitor and the first end of the coil antenna, and a second end of the seventh capacitor is grounded; wherein the NFC driving controller is configured to control the first switch tube and the second switch tube to be turned on and turned off, a first fixed end of the second single-pole double-throw switch is connected to the first end of the coil antenna, and a second fixed end of the first single-pole double-throw switch is connected to the second end of the coil antenna.

12. The device of claim 11, wherein the second switch unit comprises a third switch tube and a fourth switch tube, and the second matching unit comprises a fourth inductor, an eighth capacitor, a ninth capacitor and a tenth capacitor; a first end of the third switch tube is connected to a constant voltage, a second end of the third switch tube is connected to the NFC driving controller, and a third end of the third switch tube is connected to the fourth switch tube and a moving end of the second single-pole double-throw switch; a first end of the fourth switch tube is connected to the third end of the third switch tube and the moving end of the second single-pole double-throw switch, a second end of the fourth switch tube is connected to the NFC driving controller, and a third end of the fourth switch tube is grounded. A first end of the fourth switch is connected with a third end of the third switch and a moving end of the second SPDT switch respectively, a second end of the fourth switch is connected with the NFC drive controller, and a third end of the fourth switch is grounded; A first end of the fourth inductor is connected with a first fixed end of the second SPDT switch, a second end of the fourth inductor is connected with the eighth capacitor and the ninth capacitor respectively, and a second end of the eighth capacitor is grounded; A first end of the ninth capacitor is connected with the second end of the fourth inductor and the first end of the eighth capacitor respectively, and a second end of the ninth capacitor is connected with the tenth capacitor; A first end of the tenth capacitor is connected with the second end of the ninth capacitor and the second end of the coil antenna respectively, and a second end of the tenth capacitor is grounded; The NFC drive controller is further configured to control the third switch and the fourth switch to be turned on and turned off.

13. The apparatus of claim 12, wherein, The coil antenna comprises a third winding and a fourth winding, and the NFC device further comprises a third SPDT switch, A first end of the third winding is connected with a first fixed end of the third SPDT switch, a second end of the sixth capacitor and a first end of the seventh capacitor, and a second end of the third winding is connected with a first end of the fourth winding; A first end of the fourth winding is connected with a second end of the ninth capacitor and a first end of the tenth capacitor, a second end of the fourth winding is connected with a second fixed end of the third SPDT switch and a second fixed end of the first SPDT switch, and a moving end of the third SPDT switch is grounded through a second inductor. The NFC device further comprises a third receiving module, 14. The apparatus of claim 13, wherein, The first receiving unit is connected with the first end of the third winding and configured to detect a third voltage of the first end of the coil antenna; The second receiving unit is connected with the second end of the fourth winding and configured to detect a fourth voltage of the second end of the coil antenna; The third receiving module receives data based on the third voltage and the fourth voltage. The method is applied to the device of any one of claims 1 to 14, and the method comprises:

15. A communication method of an NFC device, characterized by, In a case where an external magnetic field is detected, the second drive module is controlled by the NFC drive controller to start to output the direct-current driving voltage; The coil antenna generates a constant magnetic field based on the direct-current driving voltage; Data transceiving between the NFC device and a first NFC device corresponding to the external magnetic field is performed by the coil antenna based on a high-frequency alternating magnetic field generated by the alternating-current driving voltage output by the first drive module. In a case where an external magnetic field is detected, the second drive module is controlled by the NFC drive controller to start to output the direct-current driving voltage, which comprises:

16. The method of claim 15, wherein, In a case where a frequency of the external magnetic field is the same as a frequency of the high-frequency alternating magnetic field, the second drive module is controlled to start to output the direct-current driving voltage. Before the second drive module is controlled by the NFC drive controller to start to output the direct-current driving voltage, the method further comprises:

17. The method according to claim 15 or 16, characterized in that, determining a first direction of the external magnetic field; ​ determining a target drive module from the first drive module and the second drive module, the target drive module outputting a direct current drive voltage to make a second direction of a constant magnetic field generated by the coil antenna same as the first direction; controlling the target drive module to start outputting the direct current drive voltage through the NFC drive controller.

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