Method for improving label reading success rate of NFC (Near Field Communication) equipment based on POS (Point of Sale) dynamic load change

Abstract

The invention discloses a method for improving the tag reading success rate of NFC (Near Field Communication) equipment based on POS (Point of Sale) dynamic load change, which comprises the following steps: simulating an NFC tag by a POS terminal, sampling an external basic load value, and setting a trigger threshold Tbase; after initialization is finished, enabling the POS terminal to detect an external field function, and collecting a signal amplitude Tlast at the moment; when the POS terminal recognizes that the card searching signal is not processed, the NFC equipment is confirmed to be close; when the POS terminal recognizes a signal detected by the low-power-consumption card, enabling an LPCD function of a fixed threshold value, and when the amplitude Tcurrent detected by the low-power-consumption card is greater than Tbase, confirming that the NFC equipment is close; when the secondary confirmation result is that the NFC equipment is close and NFC equipment interaction is not completed according to expectation, dynamic load change is introduced to promote the NFC equipment to complete the transaction; the method can effectively solve the problems of difficulty in reading the simulation tag at the POS end, incapability of normal interaction and the like caused by the fact that the NFC equipment adopts the LPCD function.

Description

Technical Field

[0001] The present invention relates to the technical field of interaction between POS machines and NFC devices, and in particular to a method for improving the success rate of NFC devices reading tags based on dynamic load changes of POS machines. Background Art

[0002] In recent years, Near Field Communication (NFC), a core technology supporting the Internet of Things (IoT) and mobile payments, has expanded its application from traditional transportation cards and access control systems to emerging areas such as smart terminal payments and device connectivity. However, significant technical bottlenecks remain in the interaction between NFC devices and point-of-sale (POS) terminals, particularly when POS terminals emulate NFC tags.

[0003] Since NFC consumes too much power when it is working, for mobile devices that support NFC functions, especially common devices such as NFC mobile phones, most manufacturers will use low-power card detection technology (LPCD) to reduce its power consumption during operation and improve battery life while keeping the NFC function always on. Low-power card detection technology detects changes in external loads by transmitting pulses at regular intervals. When the load change reaches the expected threshold, it will be considered that there is an external card approaching, and subsequent interaction will be carried out. Limited by the implementation principle of this technology, the set threshold becomes the key to the success rate of recognition, but too low a threshold is prone to false triggering. Therefore, it is difficult for NFC devices on the market to stably identify cards or NFC tags, resulting in difficulties in interacting with NFC tags and inability to interact normally. This difficulty also exists in POS applications, resulting in poor compatibility and instability when NFC devices and POS use POS simulated tags to interact. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to propose a method for improving the success rate of NFC devices reading tags based on the dynamic load changes of POS. By adjusting the initialization logic and adding detection confirmation and dynamic adjustment links, the method solves the problems of NFC devices having difficulty reading POS terminal simulated tags and being unable to interact normally due to the use of low-power card detection functions, thereby providing necessary guarantees for adding new payment methods to POS.

[0005] To achieve the above technical objectives, the present invention adopts a technical solution: a method for improving the success rate of NFC device tag reading based on POS dynamic load changes, comprising:

[0006] The POS terminal turns on the card emulation function to simulate an NFC tag, performs initialization, and samples an external basic load value, and sets a trigger threshold T according to the basic load value. base ;

[0007] After initialization, the POS terminal enables the external field detection function and collects the signal amplitude at this time, which is recorded as T last ;

[0008] The POS terminal distinguishes the detected signal according to its duration. When it recognizes the card search signal, it does not process it and confirms that the NFC device is close. When it recognizes the low-power card detection signal, the POS terminal enables the low-power card detection function with a fixed threshold. When the amplitude T detected by the low-power card detection is current Greater than T base Then confirm that the NFC device is close;

[0009] When the secondary confirmation results are both that the NFC device is close and the NFC device interaction is not completed as expected, it is determined that dynamic load changes need to be introduced to prompt the NFC device to complete the transaction.

[0010] In some embodiments, the card emulation function circuit on the POS terminal is provided with a matrix circuit for implementing multi-level adjustment of the POS terminal load;

[0011] The loads in the matrix circuit are L1, L2, L3, ..., L n , where n is the number of adjustable loads in the actual matrix circuit, n ≥ 2; when the corresponding load is selected, the amplitude change generated is ΔT1, ΔT2, ΔT3, ..., ΔT n .

[0012] In some embodiments, the card emulation function circuit on the POS terminal is mainly composed of an NFC_Reader module, a contactless antenna matching circuit, and an NFC antenna. A matrix circuit is set before and after the matching capacitor of the contactless antenna matching circuit; the optional matrix circuit includes a matrix capacitor, a matrix resistor, and a matrix inductor.

[0013] In some embodiments, when the secondary confirmation results are both that the NFC device is close and the NFC device interaction is not completed as expected, it is determined that a dynamic load change needs to be introduced to prompt the NFC device to complete the transaction, which specifically includes the following steps:

[0014] If the secondary confirmation results both indicate that the NFC device is close to the user and the NFC device interaction is not completed as expected, it is determined that a dynamic load change is required. The dynamic load change method includes the following steps:

[0015] First, calculate T last With T base The difference is recorded as ΔTnfc , ΔT nfc Compared with ΔT1, if ΔT nfc <ΔT1, then adjust the load in the matrix circuit to L n If ΔT nfc >ΔT n , then adjust the load in the matrix circuit to L1;

[0016] When ΔT1≤ΔT nfc ≤ΔT n When the load in the matrix circuit is set to the middle value Lmid, then the amplitude T at the current moment obtained by the POS terminal is current With T last Calculate the difference ΔT;

[0017] When ΔT is less than the amplitude change of the regulating circuit ΔT mid When the control matrix circuit increases the load setting to L mid+1 Otherwise, reduce the load and set it to L mid-1 .

[0018] In some embodiments, if increasing / decreasing the load still fails to trigger the active card-searching behavior of the NFC device, the step size of the single load adjustment is gradually increased.

[0019] In some embodiments, when n is an odd number, L mid =L (n+1) / 2 , when n is an even number, L mid =L n / 2 .

[0020] In some embodiments, the method for improving the success rate of NFC device tag reading based on POS dynamic load changes further includes:

[0021] After sensing the load change, the NFC device triggers its own active card search behavior and sends a card search anti-collision instruction. After the POS terminal correctly responds to the corresponding instruction, the formal interaction process begins and the normal interaction with the POS terminal is completed.

[0022] In some embodiments, the method for improving the success rate of NFC device tag reading based on POS dynamic load changes further includes:

[0023] When the POS terminal detects an NFC device approaching and confirms it is an NFC device, if the POS terminal detects that the tag content has not been read within a preset time, it will start the self-reset process;

[0024] The self-reset process resets the card reader chip / disables the response so that the NFC device believes that the tag has been removed.

[0025] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0026] 1. The present invention confirms the proximity of the NFC device through low-power card detection at the POS terminal, avoiding deviations from the expected execution process caused by false triggering.

[0027] 2. Because major device manufacturers lack a unified standard for low-power card detection, the strategies and behaviors adopted by NFC devices on the market are inconsistent. This invention uses POS-controlled simulated tags to implement load changes to complement the triggering conditions of the NFC device's low-power card detection function, prompting the NFC device to trigger active card search behavior and subsequent NFC data exchange, thus solving the stability bottleneck that exists when the POS simulates the NFC tag mode.

[0028] 3. The present invention can solve the state machine anomaly caused by interaction failure due to signal stability when NFC devices are close together. Through the abnormal reset mechanism, the state machine can be reset without moving the NFC device, facilitating normal transaction execution. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 Assist NFC devices in completing the interaction process for POS terminals;

[0031] Figure 2 Initialize the process for POS terminals;

[0032] Figure 3 NFC device proximity detection process based on external field detection and POS terminal low-power card detection;

[0033] Figure 4 It is a matrix capacitor circuit (including SOC module);

[0034] Figure 5 It is a matrix capacitor circuit (excluding SOC module);

[0035] Figure 6 Schematic diagram of the process for adjusting dynamic load;

[0036] Figure 7 This figure shows the recovery process for NFC interaction exceptions. DETAILED DESCRIPTION

[0037] The present invention will be described in further detail below with reference to the accompanying drawings and examples. It is particularly noted that the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Similarly, the following examples are only some embodiments of the present invention and are not intended to be exhaustive. All other embodiments obtained by those of ordinary skill in the art without creative effort are intended to fall within the scope of protection of the present invention.

[0038] Reference Figure 1 As shown, this embodiment provides a method for improving the success rate of NFC device tag reading based on POS dynamic load change, including: the POS terminal initially collects a basic load value, and after confirming that the NFC device is close, if the NFC device interaction is not completed as expected, the dynamic load change is performed to prompt the NFC device to complete the transaction, specifically including:

[0039] POS terminal initialization: The POS terminal turns on the card emulation function to simulate an NFC tag and initializes it (it is an existing technology for the POS terminal to simulate an NFC tag, which can be achieved by using a reader module with card emulation function). At the same time, it samples an external basic load value and sets a trigger threshold T according to the basic load value. base (like Figure 2 ), which is used for subsequent secondary confirmation that an NFC device is approaching.

[0040] Detect NFC device approaching (such as Figure 3 After the POS terminal is initialized, it will enable the external field detection function and collect the signal amplitude at this time and record it as T last (When the NFC device approaches, it will send a pulse at the microsecond level or a modulated card-searching signal.) Since the signal duration used for low-power card detection is at the microsecond level, and the signal duration used for card-searching must be greater than 5ms according to the ISO14443 protocol specification, the POS terminal will distinguish based on the detected signal duration. When a card-searching signal is identified, no processing is performed to avoid introducing new anomalies. This is the first confirmation that the NFC device is approaching. When a low-power card detection signal is identified, the POS terminal enables the low-power card detection function with a fixed threshold. Based on the threshold T base , when the low power card detects the amplitude T current (T current Indicates that the amplitude detected at the current moment is greater than T base If both confirmations indicate that an NFC device is approaching and the NFC device interaction is not completed as expected, it is determined that dynamic load changes need to be introduced to force the NFC device to complete the transaction.

[0041] Load Variation Methods: The card emulation circuit used in POS terminals primarily consists of an NFC reader module, a contactless antenna matching circuit, and an NFC antenna. Some POS terminals also include a system-on-chip (SoC) module. To achieve dynamic load adjustment, a matrix circuit must be added before and after the matching capacitors in the contactless antenna matching circuit. Matrix circuits are not limited to matrix capacitors, matrix resistors, and matrix inductors.

[0042] like Figure 4 As shown, the present invention demonstrates a feasible circuit using a matrix capacitor circuit as an example. The matrix capacitor circuit is composed of a combination of switches and capacitors. The SOC module outputs a control signal to control the switch to be turned off, thereby controlling the capacitor to be turned on and grounded, forming a loop. After the switch is turned on, the capacitor is grounded, forming a loop. The matrix capacitor is added to the capacitor of the matching circuit, increasing the capacitance on the matching circuit. As the capacitance increases, the load also increases, thereby achieving the effect of dynamic load regulation. Specifically, the GPIO control switch in the SOC module grounds the capacitor, thereby increasing the load of the matching circuit.

[0043] For some NFC chips that support output control signals, the NFC_Reader module can directly output control signals instead of the SOC module control logic, such as Figure 5 shown.

[0044] Figure 4 and Figure 5 The capacitors in the matrix capacitor circuit can be replaced by resistors or inductors to form matrix resistor and matrix inductor circuits.

[0045] The load of the matrix circuit changes from small to large as L1 (minimum load), L2, L3, ..., L n , where n is the number of adjustable loads in the actual matrix circuit, n ≥ 2; when the corresponding load is selected, the corresponding amplitude changes ΔT1, ΔT2, ΔT3, ..., ΔT n ; Among them, ΔT1=L1-L0, L0 means the matrix circuit is not loaded; similarly, ΔT2=L2-L0, ΔT3=L3-L0, ΔT n =L n -L0.

[0046] For ease of understanding, Figure 4 For example, the matrix circuit contains 4 capacitors involved in load regulation, so the number of adjustable loads is 4. When 3 capacitors are controlled to be connected to ground to form a loop, the matrix circuit load is L3, and the corresponding amplitude change is ΔT3=L3-L0; similarly, when 2 capacitors are controlled to be connected to ground to form a loop, the matrix circuit load is L2, and the corresponding amplitude change is ΔT2=L2-L0.

[0047] Load change mode (such as Figure 6 As shown): After detecting that the NFC device is close, the previously obtained T is first calculated. last With T base The difference is recorded as ΔT nfc , use this value to compare with ΔT1, if ΔT nfc <ΔT1, it is considered that the load change is too small and the load needs to be increased. Therefore, the matrix circuit load is set to L n If ΔT nfc >ΔT n , it can be considered that the value is too large and the load needs to be reduced, so the matrix circuit load is set to L1.

[0048] When the change does not meet the above conditions (ie ΔT1≤ΔT nfc ≤ΔT n When , the load of the initialization matrix circuit is set to the intermediate value L mid (When n is an odd number, Lmid=L (n+1) / 2 ; When n is an even number, L mid =L n / 2 ), then according to the current amplitude T obtained by the POS terminal current With T last Calculate the difference ΔT; when ΔT is less than the matrix circuit load change ΔT mid When the control matrix circuit increases the load setting to L mid+1 Otherwise, reduce the load and set it to L mid-1 If increasing / decreasing the load still fails to trigger the NFC device to actively search for the card, gradually increase the step size of the single load adjustment, such as L mid+1 Set to L mid+3 .

[0049] After sensing the load change, the NFC device will trigger its own active card search behavior and send a series of card search and anti-collision instructions (for example, WUPA / REQA, ANTLCOLLISON, SELECT instructions based on the ISO14443 protocol). After the POS terminal correctly responds to the card search and other corresponding instructions, the formal interaction process will begin and the normal interaction with the POS terminal will be completed.

[0050] Abnormal recovery processing (such as Figure 7 (As shown): When a POS terminal detects an NFC device approaching and confirms it as an NFC device, if the tag content is not read within a preset time, it will initiate a self-reset process. The self-reset process resets the card reader chip and disables the response, causing the NFC device to believe that the tag has been removed. This process is intended to prevent communication failures caused by NFC state machine anomalies during the NFC device approach, which could lead to abnormal interaction.

[0051] The present invention is based on the implementation principle of low-power card emulation detection. It complements the triggering conditions of LPCD through the control of the POS terminal, prompting the NFC device to initiate normal card-seeking behavior. At the same time, it adds an abnormal restart mechanism to address abnormal interaction failures caused by weak transmission signals of some devices, thereby doubly ensuring the interaction stability and reliability between the POS terminal and the NFC device.

[0052] The above descriptions are only some embodiments of the present invention and do not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for improving the success rate of NFC device reading tags based on POS dynamic load changes, characterized in that: include: The POS terminal turns on the card emulation function to simulate an NFC tag, performs initialization, and samples an external basic load value, and sets a trigger threshold T according to the basic load value. base ; After initialization, the POS terminal enables the external field detection function and collects the signal amplitude at this time, which is recorded as T last ; The POS terminal distinguishes the detected signal according to its duration. When it recognizes the card search signal, it does not process it and confirms that the NFC device is close. When it recognizes the low-power card detection signal, the POS terminal enables the low-power card detection function with a fixed threshold. When the amplitude T detected by the low-power card detection is current Greater than T base Then confirm that the NFC device is close; When the secondary confirmation results are both that the NFC device is close and the NFC device interaction is not completed, it is determined that dynamic load changes need to be introduced to prompt the NFC device to complete the transaction.

2. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 1 is characterized in that: The card emulation function circuit on the POS terminal is provided with a matrix circuit for realizing multi-level adjustment of the POS terminal load; The load changes in the matrix circuit from small to large are L1, L2, L3, ..., L n , where n is the number of adjustable loads in the actual matrix circuit; when the corresponding load is selected, the amplitude changes generated are ΔT1, ΔT2, ΔT3, ..., ΔT n .

3. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 2 is characterized in that: The card emulation function circuit on the POS terminal mainly consists of a contactless antenna matching circuit, an NFC_Reader module, and an NFC antenna. A matrix circuit is set before and after the matching capacitor of the contactless antenna matching circuit; the optional matrix circuit includes a matrix capacitor, a matrix resistor, and a matrix inductor.

4. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 2, characterized in that: If both secondary confirmations indicate that the NFC device is close to the user and the NFC device interaction is not complete, it is determined that dynamic load changes need to be introduced to force the NFC device to complete the transaction. The specific steps include: If the secondary confirmation results both indicate that the NFC device is close to the user and the NFC device interaction is not complete, it is determined that a dynamic load change is required. The dynamic load change method includes the following steps: First, calculate T last With T base The difference is recorded as ΔT nfc , ΔT nfc Compared with ΔT1, if ΔT nfc <ΔT1, then adjust the load in the matrix circuit to L n If ΔT nfc >ΔT n , then adjust the load in the matrix circuit to L1; When ΔT1≤ΔT nfc ≤ΔT n When the load in the matrix circuit is set to the middle value Lmid, then the amplitude T at the current moment obtained by the POS terminal is current With T last Calculate the difference ΔT; When ΔT is less than the amplitude change of the regulating circuit ΔT mid When the control matrix circuit increases the load setting to L mid+1 Otherwise, reduce the load and set it to L mid-1 .

5. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 4 is characterized in that: If increasing / decreasing the load still fails to trigger the NFC device to actively search for a card, gradually increase the step size of the single load adjustment.

6. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 4, characterized in that: When n is an odd number, L mid =L (n+1) / 2 , when n is an even number, L mid =L n / 2 .

7. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 1, characterized in that: Also includes: After sensing the load change, the NFC device triggers its own active card search behavior and sends a card search anti-collision instruction. After the POS terminal correctly responds to the corresponding instruction, the formal interaction process begins and the normal interaction with the POS terminal is completed.

8. The method for improving the success rate of NFC device tag reading based on POS dynamic load changes according to claim 1, characterized in that: Also includes: When the POS terminal detects an NFC device approaching and confirms it is an NFC device, if the POS terminal detects that the tag content has not been read within a preset time, it will start the self-reset process; The self-reset process resets the card reader chip / disables the response so that the NFC device believes that the tag has been removed.

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