Method and system for preventing under-screen NFC antenna interference of touch screen and POS machine

Abstract

The invention discloses a method and a system for preventing interference of an under-screen NFC (Near Field Communication) antenna of a touch screen and a POS (Point-Of-Sale) machine. The method comprises the following specific steps: step 1, carrying out optimization design on the antenna; step 2, self-adaptive time division multiplexing design; and step 3, frequency domain interference suppression design which comprises two specific steps: S31, frequency hopping and spread spectrum design and S32, filtering processing design, in the invention, the NFC antenna is designed into a multilayer annular coil and is embedded below the touch screen, the multilayer annular coil adopts a vertical stacking structure, horizontal magnetic field diffusion is reduced through vertical stacking, a magnetic flux guide layer is added at the edge of the NFC antenna, and the frequency domain interference suppression design is realized. A touch screen controller, such as a nanocrystalline strip, is used for restraining magnetic field distribution, reducing overflow interference and ensuring that 90% of energy of an NFC antenna is concentrated in the range of + / -2cm of the center of the antenna, the touch screen controller and an NFC module share clock signals and carry out time synchronization control firstly, and then NFC signals are transmitted in a non-scanning period of the touch screen, so that the false touch rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of POS machines, and in particular to a method and system for preventing interference from an under-screen NFC antenna on a touch screen, and a POS machine. Background Art

[0002] A POS machine uses a card reader to read the cardholder's magnetic stripe information on a bank card. The POS operator enters the transaction amount, and the cardholder enters their personal identification information (i.e., password). The POS then transmits this information through the UnionPay center to the issuing bank's system, completing the online transaction, providing a success or failure status, and printing the corresponding receipt. POS applications enable online transactions using credit cards, debit cards, and other bank cards, ensuring secure, fast, and accurate transactions. This eliminates the tedious manual labor of blacklist searches and order cancellations, thereby improving work efficiency.

[0003] CN118981257A - Method for Preventing Interference from Under-Screen NFC Antenna on Touch Screen and POS Terminal, which records "transmitting a first RF signal in low-power card detection mode, wherein the first RF signal has a pulse width of Ton and a frequency of Fon; filtering out signals acting on the touch screen with a duration less than Ts, where Ts>Ton, and filtering out signals acting on the touch screen with a frequency of Fon; detecting the strength of a received second RF signal, and if the strength of the second RF signal exceeds a lower strength limit setting value by more than a first difference, reducing the strength of the first RF signal until the strength of the second RF signal exceeds the lower strength limit setting value by no more than the first difference." As those skilled in the art can understand, the reference patent solves the problem of interference from the under-screen NFC antenna of a POS terminal to the touch screen through the synergistic effect of low-power card detection (LPCD) technology, signal filtering technology, and dynamic field strength control technology. By converting the interference signal from continuous interference to periodic pulse interference, subsequent filtering processing is facilitated. However, this method can only reduce interference and cannot truly avoid it.

[0004] In summary, a method, system, and POS terminal are designed to prevent interference from the under-screen NFC antenna on a touch screen. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings, the present invention provides a method, system and POS terminal for preventing interference of an under-screen NFC antenna on a touch screen.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] The method, system, and POS terminal for preventing interference from an under-screen NFC antenna on a touch screen include the following specific steps:

[0008] Step 1: Optimize antenna design. Design the NFC antenna as a multi-layer toroidal coil and embed it under the touch screen. The multi-layer toroidal coil adopts a vertically stacked structure to reduce horizontal magnetic field diffusion. Add a magnetic flux guiding layer, such as nanocrystalline ribbon, to the edge of the NFC antenna to constrain the magnetic field distribution and reduce spillover interference.

[0009] Step 2: Adaptive time-division multiplexing design: First, the touch screen controller and the NFC module share the clock signal for time synchronization control, and then transmit the NFC signal during the touch screen non-scanning period;

[0010] Step 3: Frequency domain interference suppression design, including two specific steps:

[0011] S31, frequency hopping spread spectrum design, dynamically changes the NFC carrier frequency within the range of 13.56MHz±2MHz, disperses energy peaks, and reduces interference with fixed-band touch screens. Software-defined radio (SDR) technology is used to dynamically generate frequency hopping sequences through FPGAs, synchronize frequency hopping decoding at the receiving end, and is compatible with the ISO14443 protocol.

[0012] S32, filtering processing design, integrating a programmable digital filter in the corresponding touch screen signal receiving circuit in the POS machine to detect and suppress NFC frequency band noise in real time.

[0013] Preferably, in step 1, the circuit board on which the NFC antenna is mounted uses a high-permeability flexible substrate, such as a ferrite composite material, to suppress magnetic field leakage, and the NFC antenna uses multiple strands of insulated thin wires to reduce high-frequency losses caused by the skin effect.

[0014] Preferably, step 2 also includes a dynamic priority adjustment design, which detects the user's current operation in real time through the main control chip inside the POS machine. When the touch screen is highly active, the NFC module automatically enters a low-power listening mode. When it detects that an NFC card is approaching or the user sends a command to detect the NFC card, the transmission power is temporarily increased to normal mode.

[0015] Preferably, the specific steps of step S32 are as follows:

[0016] S321, the touch screen controller samples data through the touch screen ADC and inputs it into the DSP unit in the touch screen controller;

[0017] S322, DSP unit detects the interference amplitude of 13.56MHz frequency band;

[0018] S323. A programmable digital filter dynamically generates notch filter parameters to suppress interference in the 13.56 MHz frequency band. The filter coefficients are optimized by minimizing the weighted sum of squared errors through a recursive least squares algorithm. This is used in scenarios where the interference frequency changes rapidly. The filter parameters are optimized synchronously when adjusting the NFC transmit power.

[0019] A POS machine includes a touch screen, a touch screen controller, an NFC module and a main control chip. The main control chip is electrically connected to the touch screen controller and the NFC module respectively. The touch screen controller includes a DSP unit, a programmable digital filter and a touch screen signal receiving circuit. The touch screen signal receiving circuit is electrically connected to the touch screen through the programmable digital filter. The touch screen signal receiving circuit is electrically connected to the main control chip through the DSP unit. The main control chip is electrically connected to the programmable digital filter.

[0020] Preferably, the NFC module further includes an NFC antenna.

[0021] The beneficial effects of the present invention are as follows: the method for preventing interference from the under-screen NFC antenna on the touch screen and the POS machine:

[0022] 1. The NFC antenna is designed as a multi-layer toroidal coil and embedded under the touch screen. The multi-layer toroidal coil adopts a vertical stacking structure to reduce the horizontal magnetic field diffusion. A magnetic flux guiding layer, such as nanocrystalline ribbon, is added to the edge of the NFC antenna to constrain the magnetic field distribution and reduce spillover interference. This ensures that 90% of the energy of the NFC antenna is concentrated within ±2cm of the antenna center.

[0023] 2. First, the touch screen controller and the NFC module share the clock signal for time synchronization control, and then transmit the NFC signal during the touch screen non-scanning period to reduce the false touch rate;

[0024] 3. A frequency hopping spread spectrum design is adopted to dynamically change the NFC carrier frequency within the range of 13.56MHz±2MHz, dispersing energy peaks and reducing interference with fixed-frequency touch screens. In addition, through filtering processing design, a programmable digital filter is integrated into the corresponding touch screen signal receiving circuit in the POS machine to detect and suppress NFC frequency band noise in real time, thereby improving the touch screen's interference capability with the NFC antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0026] Figure 1 This is a step diagram of a method for preventing interference from an under-screen NFC antenna on a touch screen according to the present invention. DETAILED DESCRIPTION

[0027] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0028] like Figure 1 As shown, the method, system and POS terminal for preventing the touch screen from interfering with the NFC antenna under the screen include the following specific steps:

[0029] Step 1: Optimize antenna design. Design the NFC antenna as a multi-layer toroidal coil and embed it under the touch screen. The multi-layer toroidal coil adopts a vertically stacked structure to reduce horizontal magnetic field diffusion. Add a magnetic flux guiding layer, such as nanocrystalline ribbon, to the edge of the NFC antenna to constrain the magnetic field distribution and reduce spillover interference.

[0030] Step 2: Adaptive time-division multiplexing design: First, the touch screen controller and the NFC module share the clock signal for time synchronization control, and then transmit the NFC signal during the touch screen non-scanning period;

[0031] Step 3: Frequency domain interference suppression design, including two specific steps:

[0032] S31, frequency hopping spread spectrum design, dynamically changes the NFC carrier frequency within the range of 13.56MHz±2MHz, disperses energy peaks, and reduces interference with fixed-band touch screens. Software-defined radio (SDR) technology is used to dynamically generate frequency hopping sequences through FPGAs, synchronize frequency hopping decoding at the receiving end, and is compatible with the ISO14443 protocol.

[0033] S32, filtering processing design, integrating a programmable digital filter in the corresponding touch screen signal receiving circuit in the POS machine to detect and suppress NFC frequency band noise in real time.

[0034] Specifically, in step 1, the circuit board on which the NFC antenna is mounted uses a high-permeability flexible substrate, such as a ferrite composite material, to suppress magnetic field leakage. The NFC antenna uses multiple strands of insulated thin wire to reduce high-frequency losses caused by the skin effect.

[0035] Specifically, step two also includes a dynamic priority adjustment design, which detects the user's current operation in real time through the main control chip inside the POS machine. When the touch screen is highly active, the NFC module automatically enters a low-power listening mode. When it detects that an NFC card is approaching or the user sends a command to detect the NFC card, the transmission power is temporarily increased to normal mode.

[0036] Specifically, the specific steps of step S32 are as follows:

[0037] S321, the touch screen controller samples data through the touch screen ADC and inputs it into the DSP unit in the touch screen controller;

[0038] S322, DSP unit detects the interference amplitude of 13.56MHz frequency band;

[0039] S323. A programmable digital filter dynamically generates notch filter parameters to suppress interference in the 13.56 MHz frequency band. The filter coefficients are optimized by minimizing the weighted sum of squared errors through a recursive least squares algorithm. This is used in scenarios where the interference frequency changes rapidly. The filter parameters are optimized synchronously when adjusting the NFC transmit power.

[0040] A POS machine includes a touch screen, a touch screen controller, an NFC module and a main control chip. The main control chip is electrically connected to the touch screen controller and the NFC module respectively. The touch screen controller includes a DSP unit, a programmable digital filter and a touch screen signal receiving circuit. The touch screen signal receiving circuit is electrically connected to the touch screen through the programmable digital filter. The touch screen signal receiving circuit is electrically connected to the main control chip through the DSP unit. The main control chip is electrically connected to the programmable digital filter.

[0041] Specifically, the NFC module further includes an NFC antenna.

[0042] A comprehensive analysis is conducted based on four aspects: touch screen false touch rate, touch screen false touch rate, dynamic response delay and hardware cost. The comparison table is shown in Table 1 below.

[0043] Table 1

[0044]

[0045]

[0046] In summary, compared with traditional solutions, this patent has significant improvements in four aspects: touch screen false touch rate, touch screen false touch rate, dynamic response delay and hardware cost.

[0047] The above description is for inspiration. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the content of the specification, but must be determined according to the scope of the claims.

Claims

1. A method, system, and POS terminal for preventing interference from an under-screen NFC antenna on a touch screen, characterized by: The specific steps include: Step 1: Optimize the antenna design. Design the NFC antenna as a multi-layer toroidal coil and embed it under the touch screen. The multi-layer toroidal coil adopts a vertically stacked structure, and add a magnetic flux guide layer at the edge of the NFC antenna. Step 2: Adaptive time-division multiplexing design: First, the touch screen controller and the NFC module share the clock signal for time synchronization control, and then transmit the NFC signal during the touch screen non-scanning period; Step 3: Frequency domain interference suppression design, including two specific steps: S31, frequency hopping spread spectrum design, dynamically changes the NFC carrier frequency within the range of 13.56MHz±2MHz to disperse energy peaks; S32, filtering processing design, integrating a programmable digital filter in the corresponding touch screen signal receiving circuit in the POS machine.

2. The method, system, and POS terminal for preventing under-screen NFC antenna interference on a touch screen according to claim 1, characterized in that: In the step 1, the circuit board on which the NFC antenna is mounted uses a high-permeability flexible substrate, and the NFC antenna uses multiple strands of insulated thin wires.

3. The method, system, and POS terminal for preventing under-screen NFC antenna interference on a touch screen according to claim 1, characterized in that: The step 2 also includes a dynamic priority adjustment design, which detects the user's current operation in real time through the main control chip inside the POS machine. When the touch screen is highly active, the NFC module automatically enters a low-power listening mode. When it detects that an NFC card is approaching or the user sends a command to detect the NFC card, the transmission power is temporarily increased to normal mode.

4. The method, system, and POS terminal for preventing under-screen NFC antenna interference on a touch screen according to claim 1, characterized in that: The specific steps of step S32 are as follows: S321, the touch screen controller samples data through the touch screen ADC and inputs it into the DSP unit in the touch screen controller; S322, DSP unit detects the interference amplitude of 13.56MHz frequency band; S323, dynamically generating notch filter parameters by a programmable digital filter to suppress interference in the 13.56 MHz frequency band.

5. A POS terminal, characterized in that: It includes a touch screen, a touch screen controller, an NFC module and a main control chip. The main control chip is electrically connected to the touch screen controller and the NFC module respectively. The touch screen controller includes a DSP unit, a programmable digital filter and a touch screen signal receiving circuit. The touch screen signal receiving circuit is electrically connected to the touch screen through the programmable digital filter. The touch screen signal receiving circuit is electrically connected to the main control chip through the DSP unit. The main control chip is electrically connected to the programmable digital filter.

6. A POS machine according to claim 5, characterized in that: The NFC module further includes an NFC antenna.

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