A near field communication signal processing method and system for on-off switching of a mobile phone shell antenna

Abstract

This invention discloses a near-field communication signal processing method and system for switching the on / off state of a mobile phone case antenna, belonging to the field of near-field communication technology. The method includes: monitoring the near-field communication service triggering state of the mobile terminal; generating a disable signal when the service is triggered; responding to the disable signal, performing a physical on / off switch via a radio frequency switching unit to change the characteristic impedance of the mobile phone case antenna, switching it from a resonant state to a non-resonant or high-impedance isolation state; establishing a transmissive communication link between the mobile terminal and an external third-party device; entering a preset observation period after communication ends to determine if a new service characteristic carrier pulse appears; if not, outputting a reset command to restore the mobile phone case antenna to a resonant state. This invention effectively eliminates interference from the mobile phone case antenna to the built-in near-field communication antenna, allowing payment or card reading operations to be completed without removing the mobile phone case, improving communication success rate and user experience.

Description

Technical Field

[0001] This application belongs to the field of communication technology, specifically relating to a near-field communication signal processing method and system for switching the on / off state of an antenna on a mobile phone case. Background Technology

[0002] With the widespread adoption of near-field communication (NFC) technology, it plays an increasingly crucial role in short-range interaction between mobile devices, identity verification, and mobile payments. Smart terminals exchange high-frequency data with external tags or card readers through built-in radio frequency processing chips and antenna modules. To expand the functional boundaries of smartphones, functional phone cases integrating electronic components and antenna systems are gradually becoming the mainstream in the market. These accessories achieve specific functional interactions or power transfers through radio frequency coupling with the phone.

[0003] Among them, smartphone cases equipped with dedicated antenna circuits can establish a stable signal connection with the phone's built-in near-field communication module, thereby enabling functions such as case recognition, dynamic visual effects display, or peripheral device linkage. This type of technology typically requires the phone case antenna to maintain a resonant state at a specific frequency band to ensure energy harvesting or data transmission and reception with the phone's backend signal processing unit.

[0004] However, due to the high physical overlap between the phone's built-in near-field communication antenna and the phone case antenna, when users attempt to read external third-party tags or make contactless payments, the constantly active phone case antenna can cause severe signal shielding or magnetic field interference, preventing the phone from penetrating the protective case to establish a communication connection with the target device. Furthermore, existing antenna structures lack effective path control mechanisms, making it difficult to instantly unload the antenna state under specific operational requirements, easily leading to multi-source signal conflicts. In addition, traditional solutions cannot dynamically adjust the on / off state of the RF link according to the actual communication scenario, forcing users to frequently remove the protective case during business processing, severely impacting the continuity and convenience of the user experience. Therefore, a near-field communication signal processing solution for switching the on / off state of the phone case antenna is desired. Summary of the Invention

[0005] The purpose of this invention is to provide a near-field communication signal processing method and system for switching the antenna on and off of a mobile phone case, which can effectively solve the problems in the background art mentioned above.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A near-field communication signal processing method for switching the on / off state of an antenna on a mobile phone case includes the following specific steps: Monitor the trigger status of near-field communication services on mobile terminals; When a service trigger state is identified, a disable signal is generated to suppress the resonance state of the phone case antenna; In response to the power-off signal, the radio frequency switching unit performs physical switching to change the characteristic impedance of the phone case antenna, so that the phone case antenna switches from the resonant state to the non-resonant state or the high impedance isolation state. When the phone case antenna is in a non-resonant state or a high-impedance isolation state, a transmissive communication link is established between the mobile terminal and an external third-party device. After the mobile terminal completes the near-field communication service, it enters a preset observation period and determines whether a new service characteristic carrier pulse appears during the preset observation period. If no new service characteristic carrier pulse appears within the preset observation period, a reset command is output to control the RF switch unit to restore the phone case antenna to the resonant state.

[0007] Furthermore, physical on / off switching is performed via an RF switching unit to change the characteristic impedance of the phone case antenna, including: In a short-circuit switching implementation, the radio frequency switching unit is connected in parallel across the two endpoints of the phone case antenna coil. When the power-off signal arrives, the control radio frequency switch unit is turned on, forming a short circuit path with a conduction resistance of less than 0.5 ohms, so as to forcibly eliminate the induced current on the antenna coil of the phone case.

[0008] Furthermore, physical on / off switching is performed via an RF switching unit to change the characteristic impedance of the phone case antenna, including: Using a circuit breaker switching implementation, the radio frequency switch unit is connected in series at the center tap position of the phone case antenna circuit; When the power-off signal arrives, the control radio frequency switch unit changes from the on state to the off state, forming a physical circuit with an isolation of more than 30 dB at the 13.56 MHz operating frequency, so as to completely block the formation path of loop current.

[0009] Further, a preset observation period is entered, and it is determined whether a new service characteristic carrier pulse appears within the preset observation period, specifically including: Start the timer / counter to enter a preset observation period with a duration of 100 milliseconds; During the preset observation period, the output of the unit performing the monitoring steps is checked periodically to determine whether the following three conditions are met simultaneously: The rate of change of the rising edge of the envelope signal is greater than the preset slope threshold. The electric field strength is maintained for more than 50 microseconds after the rising edge; The peak amplitude of the pulse is greater than 1.2 times the reference voltage; If both conditions are met, it is determined that a new service characteristic carrier pulse has appeared.

[0010] Furthermore, monitoring the near-field communication service triggering status of mobile terminals specifically includes: The monitoring unit located inside the phone case monitors the envelope changes of the 13.56MHz carrier in real time. The monitoring unit integrates a detector diode and a low-pass filter circuit with a cutoff frequency of 300kHz. The extracted baseband signal envelope is sampled and its amplitude is analyzed in real time. When a rising edge transition of the envelope signal is detected and the field strength is maintained for more than 50 microseconds, it is determined to be the service trigger start point signal. The rate of change of the spatial magnetic field is obtained by using miniature induction coils symmetrically distributed inside the antenna of the mobile phone case, and then converted into a voltage signal and compared with a preset reference voltage to determine the carrier signal strength parameters.

[0011] Furthermore, the switching time for physical on / off switching performed by the radio frequency switching unit is strictly controlled to be less than or equal to 5 microseconds, and the equivalent inductance of the phone case antenna is reduced to less than 5% of its original value after switching, so as to complete the conversion from interference mode to transparent mode before the anti-collision mechanism of the near field communication protocol is activated.

[0012] Furthermore, the method also includes a self-powered step: By integrating an energy harvesting module into the radio frequency control integrated circuit, a portion of the radio frequency energy emitted by the internal antenna of the mobile terminal is rectified, and the rectification efficiency is increased to greater than or equal to 65% using low-dropout synchronous rectification technology; The converted DC power is stored in a storage capacitor with a preset capacity value, and the storage capacitor is charged to a preset operating voltage within 20 milliseconds to provide energy for performing the switching action when the mobile terminal initiates communication.

[0013] Furthermore, the RF switch unit adopts a low-loss RF microelectromechanical switch or a metal-oxide-semiconductor field-effect transistor, and its anti-electrostatic discharge voltage level reaches ±15kV for air discharge and ±8kV for contact discharge; and the method also includes: when the phone case antenna is switched to transparent mode, the logic control unit drives the LED status indicator to emit a flashing signal at a specific frequency.

[0014] Furthermore, the phone case antenna is manufactured using flexible printed circuit board technology, with 4 to 8 coil turns, a line width of 0.15 mm, a line spacing of 0.1 mm, and an overall DC resistance controlled between 1.2 ohms and 2.0 ohms.

[0015] A near-field communication signal processing system for switching the on / off state of a mobile phone case antenna, comprising: The monitoring unit is used to monitor the near-field communication service triggering status of the mobile terminal in real time and obtain carrier signal strength parameters. The logic control unit, connected to the monitoring unit, is used to generate a disable signal when the service trigger state is identified, and enter a preset observation period after the mobile terminal completes the near-field communication service to determine whether a new service characteristic carrier pulse appears. If no new pulse appears, a reset command is output. The radio frequency switch unit is connected to the logic control unit and the mobile phone case antenna circuit. It is used to perform physical on / off switching in response to the power-off signal to change the characteristic impedance of the mobile phone case antenna, so that the mobile phone case antenna switches from the resonant state to the non-resonant state or the high impedance isolation state, and restores the mobile phone case antenna to the resonant state in response to the reset command. The energy harvesting module, connected to the logic control unit and the radio frequency switch unit, is used to rectify the radio frequency energy transmitted by the internal antenna of the mobile terminal and convert it into DC power to power the logic control unit and the radio frequency switch unit. The switching time of the RF switch unit to perform physical on / off switching is less than or equal to 5 microseconds, and the equivalent inductance of the phone case antenna is reduced to less than 5% of the original value after switching; the preset observation period lasts for 100 milliseconds. Furthermore, the system is encapsulated within a polyimide film layer with a thickness less than a preset thickness and is adhered to the inner surface of the phone case using adhesive.

[0016] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention completely resolves the electromagnetic shielding conflict between the phone's built-in antenna and the functional phone case antenna by introducing a dynamic on / off switching mechanism into the phone case antenna circuit. When users perform contactless payments or read third-party tags, the system can instantly suppress interference from the phone case antenna with a preset response speed, significantly improving the communication success rate of the mobile terminal. Users can smoothly complete various near-field communication services without removing the phone case, greatly enhancing the continuity of the interactive experience.

[0017] 2. The invention integrates a high-efficiency energy harvesting module that can directly utilize the radio frequency magnetic field energy emitted by the mobile terminal for self-powering, eliminating the need for an additional battery. This not only enables a thinner and lighter phone case design but also avoids the limitation of system functionality caused by battery life. The rectification efficiency reaches a preset ratio or higher, and combined with a low-power logic control unit, ensures that the system can still stably trigger antenna switching actions in weak magnetic field environments.

[0018] 3. This invention can accurately distinguish between normal service triggers and random environmental noise, with an extremely low false trigger rate. Simultaneously, the RF switching unit employs high-isolation RF microelectromechanical switches or metal-oxide-semiconductor field-effect transistors, ensuring a high degree of determinism in impedance changes during switching. The system's anti-static capability and environmental adaptability design guarantee a predetermined fault-free operating lifespan even in complex physical operating environments.

[0019] 4. This invention employs thin-film encapsulation technology, controlling the overall structural thickness within a preset range, enabling perfect adaptation to smartphone cases of various materials and shapes. Based on monitoring and control logic of standard near-field communication frequencies, it possesses strong versatility and can be widely applied to mobile terminals of different brands and models, providing key technical support for the standardization and large-scale application of functional phone cases. The solution of this invention is not only applicable to simple antenna state switching but can also be extended to the dynamic management of multi-band, multi-functional antennas, offering broad potential for technological evolution. Attached Figure Description

[0020] Figure 1 This is an overall schematic diagram of a near-field communication signal processing method used for switching the antenna on and off of a mobile phone case; Figure 2 This is the core principle diagram of the physical switching and characteristic impedance transformation of the antenna circuit in a mobile phone case; Figure 3 This is a flowchart illustrating the logic of triggering monitoring and generating disable signals for near-field communication services on mobile terminals. Figure 4 This is a schematic diagram of the multi-level interaction relationship and data flow between the monitoring unit, the logic control unit, and the radio frequency switch unit; Figure 5 This is a schematic diagram of an architecture based on the self-driving principle of radio frequency energy harvesting and environmental adaptive adjustment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0022] The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna in this application is based on the core logic of dynamically intervening in the electromagnetic characteristics of the mobile phone case antenna circuit through in-depth monitoring of the mobile terminal's radio frequency activity state, thereby ensuring that the mobile terminal's built-in antenna has interference-free transmission communication capability in specific service scenarios. This method is implemented through the following precisely defined sequence of steps: The first step is S1, which involves monitoring the near-field communication service triggering status of the mobile terminal. In this embodiment, the purpose of monitoring the near-field communication service triggering status of the mobile terminal is to identify whether the mobile terminal is in an active mode for reading data or making contactless payments.

[0023] The system achieves this identification by capturing the output commands of the mobile terminal's internal radio frequency controller or the electromagnetic energy characteristics of its overflow in real time. Specifically, the monitoring process involves continuous listening to a signal coupling interface between the mobile terminal and the phone case, which employs inductive or capacitive coupling to capture weak transitions in the 13.56MHz carrier signal. The above monitoring process is implemented through the following detailed steps.

[0024] Step S101: Real-time monitoring of carrier envelope changes at a preset frequency; the monitoring unit located inside the phone case monitors the envelope changes of the 13.56MHz carrier in real time. This monitoring unit integrates a high-sensitivity detector diode and a low-pass filter circuit.

[0025] The detector diode is a low-dropout Schottky diode, capable of extracting the envelope of millivolt-level RF induced voltage. The cutoff frequency of the low-pass filter circuit is set between 100kHz and 500kHz, typically 300kHz. This filter circuit effectively filters out the 13.56MHz carrier frequency itself and high-frequency noise interference from the environment, retaining only the baseband signal envelope representing communication commands.

[0026] Step S102: Sample and analyze the envelope signal to determine the service trigger start point; the logic control unit performs real-time sampling and amplitude analysis on the baseband signal envelope extracted in step S101. When a rising edge transition of the envelope signal is detected and the field strength maintenance time exceeds a preset time threshold, it is determined to be a service trigger start point signal initiated by the mobile terminal.

[0027] This time threshold can be pre-configured according to the actual application environment. As an optional implementation parameter, the threshold is set to 50 microseconds. This judgment logic can effectively distinguish between real communication requests and instantaneous electromagnetic pulse interference.

[0028] Step S103: Obtain the rate of change of the spatial magnetic field and determine the carrier signal strength parameters; use miniature induction coils symmetrically distributed inside the antenna of the phone case to obtain the rate of change of the spatial magnetic field. These miniature induction coils use a high-permeability nanocrystalline material as the magnetic core to improve sensing sensitivity. The induced magnetic field rate of change signal is converted into a voltage signal by a preamplifier circuit and input to the comparator input terminal inside the logic control unit.

[0029] The comparator compares the voltage signal with a preset reference voltage in real time to determine the carrier signal strength parameter under the current environment. The reference voltage is set as follows: when the phone case is not engaged in any near-field communication with the mobile terminal, the voltage amplitude corresponding to the ambient noise level is measured by the monitoring unit. 1.2 to 1.5 times this amplitude is used as the preset value of the reference voltage and stored in the register inside the logic control unit. The strength of the current carrier signal can be quantified by the high and low levels output by the comparator. This strength parameter is the key basis for subsequent adaptive adjustment and switching actions.

[0030] In summary, step S1 discloses the specific technical means for monitoring the triggering state of near-field communication services on mobile terminals. Through carrier envelope detection, time threshold judgment, and quantitative comparison of the rate of change of the spatial magnetic field, the system can accurately identify the service triggering point and obtain the carrier signal strength.

[0031] The next step is step S2, which generates the antenna suppression control logic signal. After step S1 identifies the near-field communication service triggering state of the mobile terminal and obtains the carrier signal strength parameters, this step is performed by the logic control unit generating the corresponding level switching command based on this information.

[0032] This level switching instruction has clear timing characteristics, specifically including a disable signal to suppress the resonance state of the phone case antenna and a reset instruction to restore the normal operation of the phone case antenna. The disable signal is a high-level drive pulse, while the reset instruction is a low-level state; together, they constitute the complete control logic for the RF switching unit. The above process is implemented through the following sub-steps.

[0033] Step S201: Receive service trigger status and carrier signal strength parameters; the logic control unit obtains the service trigger start point signal determined in steps S101 to S103 from the monitoring unit, and simultaneously receives the carrier signal strength parameters output by the comparator. This strength parameter is a quantized voltage value reflecting the strength of the current near-field communication magnetic field.

[0034] Step S202: Start the timer / counter and execute the false trigger confirmation logic; the timer / counter inside the logic control unit starts counting immediately after receiving the determination signal of the service trigger start point. To prevent false triggering caused by sudden changes in environmental electromagnetic fields, the logic control unit executes a confirmation logic: it continuously detects whether the service trigger signal can be maintained for a preset duration.

[0035] This preset duration can be configured according to the actual application environment, with a typical value of 100 microseconds. Only when the duration of the trigger signal exceeds this threshold will the system recognize it as a genuine service trigger, rather than a transient noise pulse.

[0036] Step S203: Generate a disable signal and dynamically adjust the pulse width according to the communication protocol; after confirming the service trigger signal is valid, the output pin of the logic control unit flips from a low level to a high level, thereby forming a drive pulse with a preset voltage amplitude. This drive pulse serves as the disable signal. The preset voltage amplitude depends on the operating voltage of the logic control unit and can be selected from common logic levels such as 1.8V, 2.5V, or 3.3V.

[0037] The pulse width of the disable signal is not fixed, but dynamically adjusted according to the type of near-field communication protocol that the mobile terminal is about to execute. The logic control unit internally stores typical communication duration parameters corresponding to different communication protocols.

[0038] For example, when a mobile terminal executes a contactless payment protocol compliant with the ISO / IEC 14443 standard, the estimated duration of its anti-collision command and data exchange frames is typically between 300 and 800 milliseconds. Based on this, the logic control unit sets the pulse width of the disable signal to a specific value within this range to ensure that the phone case antenna remains suppressed throughout the entire external reading cycle.

[0039] If the mobile terminal executes other types of near-field communication protocols, such as short-frame interactions for reading electronic tags, the pulse width is correspondingly shortened to the tens of milliseconds level. This is done to prevent the resonant circuit of the phone case antenna from canceling out or interfering with the magnetic field generated by the external reader.

[0040] Step S204: A reset command is generated to prepare for restoring the antenna's operating state. After the disable signal pulse ends, the output pin of the logic control unit returns to a low level, which serves as the reset command. The reset command is used in subsequent steps to control the RF switch unit to restore the conduction of the phone case antenna circuit, allowing the antenna to return to its normal resonant operating mode.

[0041] It should be noted that the final effective timing of the reset instruction also depends on the delayed judgment logic in step S5. This step only completes the initial generation of the level instruction.

[0042] Step S2 discloses the complete transition process from the service trigger state to the level switching command. Based on the disable and enable signals generated in step S2, the subsequent step S3 will perform a physical on / off switch of the phone case antenna circuit, that is, use the radio frequency switching unit to respond to these level commands, change the characteristic impedance of the antenna, and thus achieve effective suppression of near-field communication interference.

[0043] The next step is step S3: performing physical switching of the phone case antenna circuit; after generating the disable signal and enable signal in step S2, this step uses the controlled RF switch unit to respond to these level switching commands.

[0044] When the mobile terminal is performing external communication services, the radio frequency switching unit changes the characteristic impedance of the phone case antenna circuit by momentarily short-circuiting or momentarily opening the circuit, causing the phone case antenna to switch from its original resonant state to a non-resonant state or a high-impedance isolation state. The above physical on / off switching process is achieved through the following sub-steps.

[0045] Step S301: Select and configure the radio frequency (RF) switching unit; the RF switching unit used to perform physical on / off switching is an electronic component with extremely low parasitic parameters. Specifically, a low-loss RF microelectromechanical switch or a metal-oxide-semiconductor field-effect transistor switch can be selected.

[0046] Both devices have switching response speeds ranging from nanoseconds to microseconds, and the introduced parasitic capacitance and inductance are extremely small, so they will not have any additional impact on the original resonant characteristics of the phone case antenna.

[0047] The RF switch unit can be integrated into the circuit using two independent circuit connection structures: short-circuit switching topology and open-circuit switching topology. Designers can choose the appropriate topology based on the specific application scenario and the voltage withstand capability of the switching device. The two methods correspond to different physical connection topologies and normal switch configurations: In the short-circuit switching implementation, the radio frequency switch unit is normally in the open state, that is, the switch is not turned on when there is no disable signal; In the circuit breaker switching implementation, the radio frequency switch unit is normally in the on state, that is, the switch remains closed when there is no disable signal.

[0048] Step S302: Perform short-circuit switching; when using the short-circuit switching implementation, the RF switch unit is connected in parallel across the two endpoints of the phone case antenna coil. When the disable signal output in step S2 arrives, the disable signal is a high-level drive pulse, which directly controls the RF switch unit to turn on.

[0049] After conduction, the resistance value is less than a preset impedance threshold, which is specifically set to 0.5 ohms. Through this extremely low resistance short-circuit path, the potentials at both ends of the phone case antenna are forced to be equal, thereby eliminating the induced current in the coil caused by the alternating magnetic field.

[0050] According to Faraday's law of electromagnetic induction and Lenz's law, the disappearance of the induced current directly leads to the disappearance of the reverse canceling magnetic field generated by the antenna of the mobile phone case itself, thereby eliminating its weakening effect on the magnetic field emitted by the built-in antenna of the mobile terminal.

[0051] Step S303: Perform circuit breaker switching; when using the circuit breaker switching implementation, the RF switch unit is connected in series at the center tap position of the phone case antenna circuit or at other key nodes in the circuit. In this implementation, the RF switch unit is normally in the ON state.

[0052] When the disable signal output from step S2 arrives, the disable signal is a high-level drive pulse. This high level controls the RF switch unit to change from the on state to the off state. The isolation after disconnection is greater than a preset isolation threshold, which is specifically greater than 30 dB at a 13.56 MHz operating frequency.

[0053] This physical circuit breaking method completely blocks the formation path of loop current, making the phone case antenna equivalent to an open-circuit coil, unable to form magnetic field coupling with the built-in antenna of the mobile terminal or external devices.

[0054] Step S304: Control the switching time to ensure real-time communication. Regardless of whether short-circuit switching or open-circuit switching is used, the completion time of the instantaneous switching action, i.e., the switching time of the RF switch unit, is strictly controlled within a preset switching duration range. This switching time is defined as the time interval from the arrival of the rising edge of the disable signal at the switch control terminal to the stabilization of the switch contacts or channel state and the attainment of the specified on-resistance or isolation. The preset switching duration is set to 5 microseconds.

[0055] This fast switching mechanism ensures that the phone case antenna has completed the transition from "interference mode" to "transparent mode" before the anti-collision mechanism of the near-field communication protocol is activated, thereby avoiding waveform distortion or communication timeout errors between the mobile terminal and external devices due to switching delay.

[0056] In summary, step S3 discloses the specific implementation method of using a controlled radio frequency switch unit to perform physical on / off switching of the mobile phone case antenna circuit. By selecting radio frequency switch elements with low parasitic parameters, adopting two topologies—parallel short circuit or series open circuit—and clarifying the actions corresponding to the normal state and disable signal of the switch under each topology, the switching action is completed within 5 microseconds. The system can reliably switch the mobile phone case antenna from a resonant state to a non-resonant or high-impedance isolation state. Based on the physical on / off switching achieved in step S3, the subsequent step S4 will establish a transmissive communication link between the mobile terminal's built-in antenna and external third-party devices.

[0057] For step S4, a transmissive communication link is established. After the phone case antenna is put into a non-working state by physical switching in step S3, this step uses this state gap to establish a direct communication link between the mobile terminal and an external third-party device.

[0058] At this time, the carrier magnetic field signal emitted by the built-in antenna of the mobile terminal can penetrate the phone casing material and the phone casing antenna in a non-resonant state, and directly achieve energy coupling and bidirectional data exchange with external third-party near-field communication devices. The establishment process of the above-mentioned transmissive communication link is achieved through the following sub-steps.

[0059] Step S401 confirms that the phone case antenna is in a non-resonant state; after performing short-circuit switching or open-circuit switching in step S3, the equivalent inductance of the phone case antenna is reduced to less than 5% of its original value. This reduction significantly weakens the phone case antenna's ability to disturb the surrounding magnetic field distribution, so that the phone case antenna no longer has a significant cancellation or shielding effect on the radiation field of the mobile terminal's built-in antenna.

[0060] In this step, the system can confirm that the antenna has successfully entered the non-operating state by detecting the status feedback of the RF switch unit or monitoring the impedance change of the antenna circuit.

[0061] In step S402, the mobile terminal's built-in antenna transmits a carrier magnetic field signal; the near-field communication controller inside the mobile terminal drives its built-in antenna to transmit a 13.56 MHz carrier magnetic field signal. When this signal passes through the phone casing material and the phone casing antenna, which is in a non-resonant state, the attenuation and distortion are minimized. According to the principle of electromagnetic wave propagation, when the equivalent inductance of the phone casing antenna is significantly reduced, the resulting eddy current loss and reflection loss are significantly reduced.

[0062] Step S403: Establish energy coupling with an external third-party device; the magnetic field emitted by the mobile terminal's built-in antenna penetrates the phone case and forms mutual inductance coupling with the induction coil of the external third-party near-field communication device. At this time, the mutual inductance coefficient between the mobile terminal's built-in antenna and the external device increases to above a preset mutual inductance threshold.

[0063] The magnetic field strength after penetrating the phone case is no less than a preset magnetic field strength value at a predetermined distance from the case surface. This predetermined distance is 4 centimeters, and the preset magnetic field strength value is 1.5 amperes per meter. This field strength level fully meets the requirements of near-field communication standards such as ISO / IEC 14443 for minimum field strength and waveform envelope.

[0064] The above mutual inductance coupling relationship is described by the following formula: ; in: The mutual inductance coefficient between the built-in antenna of a mobile terminal and an external third-party near-field communication device is expressed in Henry. It represents the coupling coefficient between the built-in antenna of the mobile terminal and the antenna of the external device. It is a dimensionless real number and its value usually ranges from 0 to 1. The self-inductance value of the built-in antenna in a mobile terminal, expressed in Henry; The inductance of the inductor coil of an external third-party near-field communication device is expressed in Henry.

[0065] Step S3 disables the phone case antenna, significantly reducing the coupling coefficient of the phone case antenna. The attenuation effect of the value ensures the mutual inductance coefficient. Maintain within the preset range required for stable communication.

[0066] Step S404: Establish a two-way data exchange channel; based on the established energy coupling, the mobile terminal and external third-party devices conduct two-way data exchange according to the near-field communication protocol specification. The mobile terminal can read information from the external tag or complete transaction instruction interaction with the contactless payment terminal.

[0067] At this point, since the interference from the phone case antenna has been eliminated, the quality of the communication link is basically the same as when the phone is not covered by a protective case.

[0068] Step S4 details how the mobile terminal establishes a transmissive communication link with an external third-party device after the phone case antenna is physically switched on and off. By confirming the antenna's non-resonant state, establishing mutual inductive coupling using the principle of electromagnetic induction, and providing a quantitative formula for the mutual inductance coefficient and the explicit meaning of each letter, those skilled in the art can understand and implement the process of establishing this communication link. Based on the transmissive communication achieved in step S4, the subsequent step S5 will automatically reset the phone case antenna's operating state after the communication ends.

[0069] Finally, in step S5, the antenna working state is automatically reset. After the mobile terminal completes the near-field communication service, the system needs to automatically restore the phone case antenna to the normal resonant working state to ensure that the phone case's own functional modules can continue to transmit energy or interact with the phone.

[0070] Step S5 involves introducing an intelligent hysteresis judgment mechanism to avoid unnecessary switching caused by brief gaps between communication data packets. The specific implementation process of step S5 is as follows: Step S501: Detect the termination of communication service or the disappearance of carrier signal; the logic control unit continuously monitors changes in the mobile terminal's radio frequency field. Monitoring is based on two independent criteria: First, the amplitude of the baseband signal envelope output by the monitoring unit remains below a preset noise floor threshold, which is set to 1.2 times the ambient noise floor voltage amplitude; second, the carrier signal strength parameter output by the comparator continuously decreases to below a preset service threshold, which is set to 0.5 times the reference voltage. When either of the above criteria is met and the duration exceeds 10 microseconds, the logic control unit determines that the current near-field communication service has ended. At this time, the system does not immediately perform an antenna reset, but instead enters a preset observation period.

[0071] Step S502: Enter the preset observation period and wait for the carrier pulse; the logic control unit starts a built-in timer / counter to enter an observation period of duration T. The specific value of T is pre-configured by the internal register of the logic control unit, and its value is determined based on the statistical characteristics of the data packet interval of commonly used near-field communication protocols for mobile terminals. As an feasible configuration, T is set to 100 milliseconds. During the observation period, the monitoring unit continues to maintain the envelope detection and amplitude comparison functions of the 13.56MHz carrier signal, and the logic control unit records in real time whether a new envelope rising edge appears.

[0072] Step S503: Determine whether a new service characteristic carrier pulse appears during the observation period; during the observation period T, the system will check the output of the monitoring unit cycle by cycle. To determine whether it is a "service characteristic carrier pulse," the following three conditions must be met simultaneously: Condition 1: The rate of change of the rising edge of the envelope signal is greater than a preset slope threshold, which is set to 0.3 volts per microsecond; Condition 2: The electric field strength is maintained for more than 50 microseconds after the rising edge; Condition 3: The peak amplitude of the pulse is greater than 1.2 times the reference voltage.

[0073] If all three conditions are met simultaneously, it is determined to be a new service characteristic carrier pulse. At this time, the system determines that the mobile terminal is conducting continuous data packet interaction or is about to initiate the next round of communication. The system will immediately clear the observation period timer and jump back to step S2 to regenerate the disable signal and continue to keep the phone case antenna in a non-resonant state.

[0074] If no pulse meeting the above three conditions is detected by the end of the observation period, the system determines that the mobile terminal has completely exited the near-field communication mode and can safely restore the working state of the phone case antenna.

[0075] Step S504: Output a low-level reset signal and control the RF switch unit to return to normal operation. When the observation period ends and no new service pulse is detected, the output pin of the logic control unit changes from a high-level or high-impedance state to a low-level state. The voltage value of this low level is equal to the digital ground potential of the logic control unit, typically 0 volts. This low level is the reset command, directly applied to the control terminal of the RF switch unit.

[0076] The RF switch unit responds to a reset low level according to its preset topology: If a short-circuit switching implementation is used, the RF switch unit is normally in the open state. A low-level reset keeps the RF switch unit open, and no longer applies a conduction control signal, thereby releasing the short-circuit connection between the two terminals of the phone case antenna. The two terminals of the antenna circuit return to the open-circuit state, and the coil can normally induce voltage at both ends.

[0077] If the circuit-breaking switching implementation is adopted, the RF switch unit is normally in the ON state. A low-level reset restores the RF switch unit to the ON state, that is, the switch changes from the OFF state to the ON state, the node connected in series in the antenna circuit is reconnected, and the antenna circuit forms a closed loop.

[0078] The normal connection positions in both of the above topologies are fixed during system initialization via hardware wiring or register configuration and will not change during operation.

[0079] In step S505, the phone case antenna returns to its resonant operating state; after the RF switch unit is reset, the electrical integrity of the phone case antenna circuit is restored. Specifically, this manifests as follows: For short-circuit switching: the two ends of the antenna coil are no longer short-circuited, and the coil's own inductance... Restore to design values, typically between 1.2 and 2.5 microhenries; matching capacitor. After normal connection, the antenna resonant frequency returned to 13.56 MHz.

[0080] For the circuit breaker switching method: when the series switch is turned on, the antenna circuit forms a closed path, and the induced current can flow normally; At the same time, the capacitors and resistors in the impedance matching network are restored to their initial connection state.

[0081] At this point, the antenna re-enters a resonant operating state that matches the built-in antenna of the mobile terminal. The phone case antenna can then normally receive the radio frequency magnetic field energy emitted by the phone and, after rectification, supply this energy to the phone case's built-in identification module or energy harvesting module. Simultaneously, the data interaction function between the phone case and the phone is restored; for example, the phone case can send its identification or status information to the phone.

[0082] Thus, step S5 fully describes the entire process from the end of communication to the automatic recovery of the antenna state. This reset mechanism, together with steps S1 to S4, such as service trigger monitoring, suppression signal generation, physical on / off switching, and establishment of the transmission communication link, forms a closed-loop control logic.

[0083] The entire signal processing method achieves dynamic switching between the phone case antenna and the "normal working mode" and "transparent communication mode" through the coordinated operation of three stages: monitoring, switching, and resetting. This ensures both the success rate of communication during contactless payments or card reading operations and the continuous availability of the phone case's own functional modules. Subsequent embodiments will further illustrate the system's hardware configuration and micro-control strategies.

[0084] In this embodiment, the mobile phone case antenna is manufactured using flexible printed circuit board (FPC) technology. Its coil turns are a preset number, for example, 4 to 8 turns; the line width is a preset width, for example, 0.15 mm; and the line spacing is a preset spacing, for example, 0.1 mm. The overall DC resistance of the antenna is strictly controlled within a preset resistance range, for example, 1.2 ohms to 2.0 ohms. At an operating frequency of 13.56 MHz, the antenna's quality factor Q is adjusted to a preset range, for example, 30 to 50, through an impedance matching network to ensure efficient energy harvesting capability during normal operation.

[0085] Furthermore, the aforementioned radio frequency switching unit is integrated into a miniature radio frequency control integrated circuit (ASIC). In addition to the logic control unit and the switching unit, this integrated circuit also integrates an energy harvesting module. This energy harvesting module rectifyes a portion of the radio frequency energy emitted by the mobile terminal's internal antenna, converting it into DC electrical energy and storing it in a storage capacitor of a preset capacity. This self-powered architecture eliminates the need for an additional battery. The rectification efficiency of the energy harvesting module is improved to a value greater than or equal to a preset efficiency, such as 65%, by employing low-dropout synchronous rectification technology. The storage capacitor charges to a preset operating voltage, such as 2.0V, in less than a preset duration threshold, such as 20 milliseconds, ensuring that the system has sufficient energy to perform the switching action the instant the mobile terminal initiates communication.

[0086] In another alternative implementation path, the RF switching unit is positioned after the impedance matching network of the phone case antenna circuit. "Detuning switching" is achieved by changing the connection state of the matching capacitor or inductor array. Specifically, at least one capacitor is switched into the circuit in parallel by controlling a multiplexer switch. The capacitance value of the parallel capacitor is calculated based on the target resonant frequency of 15MHz and the original inductance of the antenna; for example, a capacitor in the range of 100pF to 300pF can be used. This shifts the antenna's resonant frequency above a first preset frequency, such as above 15MHz, thereby avoiding the second preset frequency band of 13.56MHz. This detuning strategy can also achieve the purpose of suppressing interference, and the voltage withstand requirement for the switching devices is relatively low.

[0087] On the other hand, a near-field communication signal processing system and its micro-control strategy for switching the antenna on and off in a mobile phone case are presented. The system is completely encapsulated within a thin film layer with a thickness less than a preset value and adhered to the inner surface of the mobile phone case using adhesive. The thin film layer is made of polyimide with a specific dielectric constant, which is within a preset range to reduce the parasitic capacitance effect on high-frequency radio frequency signals.

[0088] The system consists of a monitoring unit, a logic control unit, an RF switch unit, and an energy harvesting module. The monitoring unit not only identifies trigger states but also performs security verification. In the security verification step, the logic control unit performs preliminary baseband demodulation on the carrier signal captured by the monitoring unit. By identifying the preamble and specific instruction format in the signal, it confirms that the signal indeed originates from a legitimate external card reader request or an active scanning request from the mobile terminal, and not from random pulses or malicious interference sources in the environment.

[0089] If the signal is confirmed to be legitimate, the system will then perform the subsequent physical switching action; otherwise, the phone case antenna will remain in its normal resonant position.

[0090] The logic control unit internally contains a sophisticated state machine model, which includes standby, identification, service, and recovery states. The state machine smoothly transitions between these states based on the voltage amplitude, pulse width, and duration input from the monitoring unit. For example, the threshold voltage for transitioning from standby to identification is set as a first threshold, while transitioning from identification to service requires detecting a data stream conforming to specific protocol characteristics. The fault tolerance design of the transition logic is within a preset tolerance range, allowing for a certain percentage of bit errors in the input signal to improve the system's robustness in non-ideal magnetic field environments.

[0091] The RF switch unit is physically located close to the antenna's feed point. Considering the complex physical environment encountered by phone cases in daily use, the RF switch unit integrates electrostatic discharge (ESD) protection. Its ESD voltage level reaches a preset level, such as ±15kV for air discharge and ±8kV for contact discharge, ensuring that the internal micro-integrated circuitry will not fail due to ESD breakdown under the static electricity generated by frequent removal and installation of phone cases.

[0092] In addition, the system is equipped with a tiny LED status indicator, with a package size of 0201 or smaller. This indicator is directly driven by the logic control unit. When the phone case antenna is short-circuited or open-circuited, i.e., when switching to transparent mode, the indicator flashes at a specific frequency, providing the user with intuitive physical feedback that the current communication switching state has been activated.

[0093] To achieve more precise frequency management, the antenna resonant frequency adjustment in this embodiment follows the following formula: ; in, The equivalent resonant frequency after switching. This refers to the inductance value of the phone case antenna. For the initial matching capacitor, Additional compensation capacitors are introduced for the RF switching unit. These are achieved through precise pre-setting. The value can make It precisely deviates from the main frequency of 13.56MHz to achieve the preset suppression effect.

[0094] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects.

[0095] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A near-field communication signal processing method for switching the on / off state of an antenna on a mobile phone case, characterized in that, Includes the following steps: Monitor the trigger status of near-field communication services on mobile terminals; When a service trigger state is identified, a disable signal is generated to suppress the resonance state of the phone case antenna; In response to the power-off signal, the radio frequency switching unit performs physical switching to change the characteristic impedance of the phone case antenna, so that the phone case antenna switches from the resonant state to the non-resonant state or the high impedance isolation state. When the phone case antenna is in a non-resonant state or a high-impedance isolation state, a transmissive communication link is established between the mobile terminal and an external third-party device. After the mobile terminal completes the near-field communication service, it enters a preset observation period and determines whether a new service characteristic carrier pulse appears during the preset observation period. If no new service characteristic carrier pulse appears within the preset observation period, a reset command is output to control the RF switch unit to restore the phone case antenna to the resonant state.

2. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, Physical on / off switching is performed via an RF switching unit to change the characteristic impedance of the phone case antenna, including: In a short-circuit switching implementation, the radio frequency switching unit is connected in parallel across the two endpoints of the phone case antenna coil. When the power-off signal arrives, the control radio frequency switch unit is turned on, forming a short circuit path with a conduction resistance of less than 0.5 ohms, so as to forcibly eliminate the induced current on the antenna coil of the phone case.

3. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, Physical on / off switching is performed via an RF switching unit to change the characteristic impedance of the phone case antenna, including: Using a circuit breaker switching implementation, the radio frequency switch unit is connected in series at the center tap position of the phone case antenna circuit; When the power-off signal arrives, the control radio frequency switch unit changes from the on state to the off state, forming a physical circuit with an isolation of more than 30 dB at the 13.56 MHz operating frequency, so as to completely block the formation path of loop current.

4. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, Enter a preset observation period and determine whether a new service characteristic carrier pulse appears within the preset observation period, specifically including: Start the timer / counter to enter a preset observation period with a duration of 100 milliseconds; During the preset observation period, the output of the unit performing the monitoring steps is checked periodically to determine whether the following three conditions are met simultaneously: The rate of change of the rising edge of the envelope signal is greater than the preset slope threshold. The electric field strength is maintained for more than 50 microseconds after the rising edge; The peak amplitude of the pulse is greater than 1.2 times the reference voltage; If both conditions are met, it is determined that a new service characteristic carrier pulse has appeared.

5. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, Monitoring the near-field communication service triggering status of mobile terminals, specifically including: The monitoring unit located inside the phone case monitors the envelope changes of the 13.56MHz carrier in real time. The monitoring unit integrates a detector diode and a low-pass filter circuit with a cutoff frequency of 300kHz. The extracted baseband signal envelope is sampled and its amplitude is analyzed in real time. When a rising edge transition of the envelope signal is detected and the field strength is maintained for more than 50 microseconds, it is determined to be the service trigger start point signal. The rate of change of the spatial magnetic field is obtained by using miniature induction coils symmetrically distributed inside the antenna of the mobile phone case, and then converted into a voltage signal and compared with a preset reference voltage to determine the carrier signal strength parameters.

6. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, The switching time for physical on / off switching via the RF switching unit is strictly controlled to be less than or equal to 5 microseconds, and the equivalent inductance of the phone case antenna is reduced to less than 5% of its original value after switching, so as to complete the conversion from interference mode to transparent mode before the anti-collision mechanism of the near-field communication protocol is activated.

7. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, The method also includes a self-powered step: By integrating an energy harvesting module into the radio frequency control integrated circuit, a portion of the radio frequency energy emitted by the internal antenna of the mobile terminal is rectified, and the rectification efficiency is increased to greater than or equal to 65% using low-dropout synchronous rectification technology; The converted DC power is stored in a storage capacitor with a preset capacity value, and the storage capacitor is charged to a preset operating voltage within 20 milliseconds to provide energy for performing the switching action when the mobile terminal initiates communication.

8. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, The radio frequency switch unit uses a low-loss radio frequency microelectromechanical switch or a metal-oxide-semiconductor field-effect transistor, and its anti-electrostatic discharge voltage level reaches ±15kV for air discharge and ±8kV for contact discharge; in addition, the method also includes: when the phone case antenna is switched to transparent mode, the logic control unit drives the light-emitting diode status indicator to emit a flashing signal at a specific frequency.

9. The near-field communication signal processing method for switching the on / off state of a mobile phone case antenna according to claim 1, characterized in that, The phone case antenna is manufactured using flexible printed circuit board technology. Its coil has 4 to 8 turns, a line width of 0.15 mm, a line spacing of 0.1 mm, and an overall DC resistance controlled between 1.2 ohms and 2.0 ohms.

10. A near-field communication signal processing system for switching the on / off state of an antenna on a mobile phone case, wherein it is applied to the method described in any one of claims 1-9, characterized in that, include: The monitoring unit is used to monitor the near-field communication service triggering status of the mobile terminal in real time and obtain carrier signal strength parameters. The logic control unit, connected to the monitoring unit, is used to generate a disable signal when the service trigger state is identified, and enter a preset observation period after the mobile terminal completes the near-field communication service to determine whether a new service characteristic carrier pulse appears. If no new pulse appears, a reset command is output. The radio frequency switch unit is connected to the logic control unit and the mobile phone case antenna circuit. It is used to perform physical on / off switching in response to the power-off signal to change the characteristic impedance of the mobile phone case antenna, so that the mobile phone case antenna switches from the resonant state to the non-resonant state or the high impedance isolation state, and restores the mobile phone case antenna to the resonant state in response to the reset command. The energy harvesting module, connected to the logic control unit and the radio frequency switch unit, is used to rectify the radio frequency energy transmitted by the internal antenna of the mobile terminal and convert it into DC power to power the logic control unit and the radio frequency switch unit. The switching time of the RF switch unit to perform physical on / off switching is less than or equal to 5 microseconds, and the equivalent inductance of the phone case antenna is reduced to less than 5% of the original value after switching; the preset observation period lasts for 100 milliseconds. Furthermore, the system is encapsulated within a polyimide film layer with a thickness less than a preset thickness and is adhered to the inner surface of the phone case using adhesive.

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