Ink screen circuit based on NFC passive driving

Abstract

The utility model belongs to ink screen circuit technical field discloses a kind of ink screen circuit based on NFC passive drive, wherein, including NFC antenna circuit, for receiving radio frequency signal;Rectifier boost module is electrically connected with NFC antenna circuit, is configured to be used for rectifying radio frequency signal as direct current signal;Energy storage module is electrically connected with the output end of rectifier boost module;Power control module, its input end is electrically connected with the output end of rectifier boost module, output end and energy storage module circuit connection;DCDC step-down module, its input end is electrically connected with energy storage module, output end connects ink screen drive interface;Wherein, when power control module is turned on, energy storage module and the input end of DCDC step-down module are electrically connected, for the output voltage of energy storage module is stepped down as the drive voltage of preset range;DCDC module output voltage is adjustable in preset range, can be adapted to a variety of different specifications and brand ink screen module, enhance the versatility and applicability of system.

Description

TECHNICAL FIELD

[0001] The utility model relates to handheld communication technical field, especially to a kind of ink screen circuit based on NFC passive drive. BACKGROUND

[0002] In prior art, the circuit for driving electronic ink screen usually has strong customization characteristics, often relies on specific model control chip, fixed communication protocol and voltage level, for example, some control schemes are based on special controller design, and its output voltage, pin definition and communication interface are often only matched with ink screen module of specific manufacturer, difficult to replace or cross-brand adaptation, for different models of ink screen, especially the working voltage fluctuates between 1.8V to 5V, SPI / I 2 C and other differences exist in communication interface, existing control circuit often cannot be directly adapted, need to replace circuit board or carry out additional software and hardware development, increase design cost and maintenance difficulty, in addition, in actual application, part of circuit structure lacks adjustability in output voltage or interface configuration, limits the versatility and expansibility of system between multi-specification electronic paper display module.

[0003] Therefore, an ink screen circuit based on NFC passive drive is proposed to solve the above problems. CONTENT OF UTILITY MODEL

[0004] The main purpose of the utility model is to provide an ink screen circuit based on NFC passive drive, aiming at solving the problem that existing circuit for driving electronic ink screen is difficult to adapt to ink screen with different voltage and interface.

[0005] In order to realize the above-mentioned utility model purpose, the utility model provides an ink screen circuit based on NFC passive drive, comprising:

[0006] NFC antenna circuit, for receiving radio frequency signal;

[0007] Rectifier boost module, electrically connected with the NFC antenna circuit, configured to rectify the radio frequency signal into direct current signal;

[0008] Energy storage module, electrically connected with the output end of the rectifier boost module;

[0009] Power supply control module, its input end is electrically connected with the output end of the rectifier boost module, and the output end is electrically connected with the energy storage module circuit;

[0010] DCDC step-down module, its input end is electrically connected with the energy storage module, and the output end is connected with ink screen driving interface;

[0011] When the power control module is turned on, the energy storage module is electrically connected to the input terminal of the DC-DC step-down module, which is used to step down the output voltage of the energy storage module to a driving voltage within a preset range.

[0012] Furthermore, it also includes an automatic power-off module, the input terminal of which is electrically connected to the energy storage module. The automatic power-off module triggers the DC-DC step-down module through the energy storage module to shut down the output of the EN pin of the DC-DC step-down module.

[0013] Furthermore, the rectifier boost module includes an RF input port and multiple rectifier diodes. The RF input port is electrically connected to the NFC antenna circuit, and the input terminals of the multiple rectifier diodes are respectively electrically connected to the RF input port.

[0014] The output terminals of the rectifier diodes respectively constitute the positive and negative DC terminals.

[0015] Furthermore, the rectifier boost module includes a Zener diode, the input terminal of which is connected to the output terminal of the rectifier diode, and the output terminal of which is connected to the input terminal of the power control module. This Zener diode is used to limit the DC power output by the rectifier diode and supply the controlled DC voltage to the energy storage module.

[0016] Furthermore, the energy storage module includes multiple energy storage capacitor groups connected in parallel, the multiple energy storage capacitor groups are connected to the output terminal of the power control module, and the output terminal of the multiple energy storage capacitor groups is connected to the input terminal of the DC-DC buck module.

[0017] Furthermore, the input terminal of the DC-DC step-down module is connected to the output terminal of the energy storage module, and the output terminal is connected to the e-ink screen driver interface;

[0018] The DC-DC step-down module includes an enable control terminal EN. When the voltage of the energy storage capacitor bank is lower than a set threshold, the DC-DC step-down module shuts down to enable automatic power-off after the image is completed.

[0019] Furthermore, the DC-DC step-down module includes:

[0020] The DCDC chip has its input terminal connected to the output terminal of the energy storage module, and its output terminal connected to the input terminal of the e-ink screen driver interface.

[0021] An inductor, one end of which is connected to the switching output pin of the DC-DC chip, and the other end of which is connected to the output node of the buck module;

[0022] Multiple parallel-connected output filter capacitors are electrically connected to the output node to smooth the output voltage.

[0023] A voltage divider resistor is connected at one end to the output node and at the other end to the feedback pin of the buck chip to form a closed-loop regulation of the output voltage.

[0024] Furthermore, the DC-DC chip includes an enable control pin, which is connected to the output terminal of the automatic power-off module;

[0025] The automatic power-off module is used to monitor the voltage of the energy storage module. When the energy storage voltage is detected to be lower than a preset threshold, it outputs a shutdown control signal to the enable control pin so that the DC-DC chip shuts down.

[0026] Beneficial effects:

[0027] This utility model discloses an NFC-based passive driving e-ink screen circuit, comprising: an NFC antenna circuit for receiving radio frequency signals; a rectifier-boost module electrically connected to the NFC antenna circuit and configured to rectify the radio frequency signals into DC signals; an energy storage module electrically connected to the output of the rectifier-boost module; a power control module whose input is electrically connected to the output of the rectifier-boost module and whose output is connected to the energy storage module circuit; and a DC-DC buck module whose input is electrically connected to the energy storage module and whose output is connected to the e-ink screen driving interface. When the power control module is turned on, the energy storage module is electrically connected to the input of the DC-DC buck module to step down the output voltage of the energy storage module to a driving voltage within a preset range. This embodiment organically combines the NFC antenna, rectifier-boost module, energy storage module, power control module, and DC-DC buck module to form a complete power system that can drive an e-ink screen display without an external power supply or battery. The output voltage of the DC-DC module is adjustable within a preset range, adaptable to various e-ink screen modules of different specifications and brands, enhancing the system's versatility and applicability. Attached Figure Description

[0028] Fig. 1 This is an antenna circuit diagram of an embodiment of the NFC passive driving e-ink screen circuit of this utility model;

[0029] Fig. 2 This is a schematic diagram of NFC rectification and energy storage of an e-ink screen circuit based on NFC passive drive according to an embodiment of the present invention.

[0030] Fig. 3 This is a circuit diagram of a DC-DC step-down circuit adapted to different voltage e-ink screens based on NFC passive driving, according to an embodiment of this utility model.

[0031] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0032] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0033] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly and specifically defined.

[0034] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] Reference Figs. 1 to 3The utility model discloses an e-ink screen circuit based on NFC passive driving, comprising:

[0037] NFC antenna circuit, used to receive radio frequency signals;

[0038] The rectifier boost module, electrically connected to the NFC antenna circuit, is configured to rectify the radio frequency signal into a DC signal.

[0039] The energy storage module is electrically connected to the output terminal of the rectifier boost module;

[0040] The power control module has its input terminal electrically connected to the output terminal of the rectifier boost module, and its output terminal connected to the energy storage module circuit.

[0041] The DC-DC step-down module has its input terminal electrically connected to the energy storage module and its output terminal connected to the e-ink screen driver interface.

[0042] When the power control module is turned on, the energy storage module is electrically connected to the input terminal of the DC-DC step-down module, which is used to step down the output voltage of the energy storage module to a driving voltage within a preset range.

[0043] This embodiment aims to provide a passive e-ink screen driving circuit based entirely on NFC power transfer. Its core objective is to drive various e-ink screen modules in a simple, energy-efficient, and highly compatible manner without using batteries or external power sources.

[0044] In the design, NFC radio frequency signals are used as the sole power source. After rectification, a stable DC voltage is provided, and energy is temporarily stored using an energy storage capacitor. The system determines whether to inject the rectified energy into the energy storage unit through a control circuit. Subsequently, the DC-DC step-down module outputs an adaptive voltage for the e-ink screen, thereby achieving passive, automated, and low-power control of the entire power chain.

[0045] Specifically, when an external NFC device approaches, the NFC antenna circuit receives a 13.56MHz radio frequency signal, which enters the rectifier boost module via a matching circuit. The radio frequency AC signal is converted into DC voltage by a rectifier diode bridge, and the output voltage is limited by a regulator to ensure safety and reliability. When the main control logic (such as the automatic power-off module or the image printing signal) triggers the power control module to conduct, the rectified output is sent to the energy storage module via the Q1 switch, and the capacitor begins to charge and store energy. After the energy storage module voltage rises to the DC-DC converter's operating voltage, the DC-DC converter buck module starts, outputting a stable voltage to supply the e-ink screen for image printing. After the image printing is completed, the energy storage voltage drops. When it falls below a set threshold, the system uses a control signal to stop the DC-DC converter, achieving automatic power-off. To prevent energy waste, this embodiment relies on NFC radio frequency power, eliminating the need for batteries or power supply connections, making it suitable for enclosed, portable, and non-removable scenarios. This solution also omits traditional MCUs and power management chips, employing simple and reliable voltage control logic, significantly reducing the number of components and hardware costs. Through the cooperation of the power control module and energy storage module, it supports automatic power-off after screen swiping, reducing energy consumption and extending system standby time. The DC-DC module output voltage can be adjusted within the range of 1.8V to 5V, adapting to various brands, sizes, and color grades of e-ink screen modules to meet different product specifications. It is particularly suitable for scenarios such as electronic price tags, electronic paper name badges, information cards, and customized phone cases, possessing excellent platform versatility and mass production value.

[0046] Furthermore, it also includes an automatic power-off module, the input terminal of which is electrically connected to the energy storage module. The automatic power-off module triggers the DC-DC step-down module through the energy storage module to shut down the output of the EN pin of the DC-DC step-down module.

[0047] In NFC passive power supply systems, due to the limited and unstable energy source, if power is continuously supplied to the DC-DC module after the image is scanned, the energy storage will be quickly depleted, leading to a drop in system voltage, failure of subsequent functions, or even system crashes or erroneous operations.

[0048] To improve system energy efficiency and safety, this embodiment introduces an automatic power-off module between the energy storage module and the DC-DC step-down module. This module monitors the output voltage status of the energy storage module and automatically shuts down the DC-DC module when the voltage falls below a preset threshold. This prevents capacitor over-discharge or DC-DC module idling. It requires no MCU intervention and is entirely controlled by hardware logic. This structure is particularly suitable for e-ink screen scenarios with high instantaneous power consumption during image processing and discontinuous operating cycles, effectively extending energy storage utilization time and avoiding energy waste. When the energy storage module capacitor is charged to a set value, the automatic power-off module does not intervene. When the EN pin is high, the DC-DC module operates normally. The output voltage powers the e-ink screen driver interface. As the e-ink screen refreshes, the load decreases, but the DC-DC module continues to operate. The energy storage capacitor voltage gradually decreases. The automatic power-off module continuously monitors the energy storage module output. When the voltage drops below a preset threshold, it triggers the control logic. The automatic power-off module outputs a low level to the EN pin of the DC-DC chip. The chip stops working, and the output is turned off. The system enters a sleep state, waiting for the next NFC energy input. This avoids DC-DC idle consumption and output instability. This control can be implemented using low-power hardware circuits such as voltage comparators, voltage divider networks, and MOSFET gating logic, without the need for additional MCU intervention.

[0049] Furthermore, the rectifier boost module includes an RF input port and multiple rectifier diodes. The RF input port is electrically connected to the NFC antenna circuit, and the input terminals of the multiple rectifier diodes are respectively electrically connected to the RF input port.

[0050] The output terminals of the rectifier diodes respectively constitute the positive and negative DC terminals.

[0051] In this embodiment, the rectifier boost module includes an RF input port and multiple rectifier diodes. The RF input port is used to receive a 13.56MHz RF AC signal from the NFC antenna circuit. Specifically, it includes two terminals, RF1 and RF2, which are electrically connected to the two ends of the NFC antenna, respectively. The multiple rectifier diodes are preferably four rectifier diodes, D1, D2, D3, and D4, forming a bridge rectification structure.

[0052] In this design, the input terminals of D1 and D2 are connected to the forward paths of RF1 and RF2, respectively, and the input terminals of D3 and D4 are connected to the reverse paths of RF1 and RF2, respectively, to achieve full-wave rectification. The output terminals of the rectifier diodes form the positive and negative terminals of the DC output, respectively. The output sides of D1 and D2 are connected together to form the positive voltage node after rectification, and the output sides of D3 and D4 are connected together to form the negative terminal node (i.e., ground). This structure can convert the high-frequency AC energy input from both ends into a unidirectional stable DC output voltage. Through the design of this embodiment, the high-frequency AC signal input from the NFC antenna is effectively rectified and a stable DC energy source is provided, providing an energy foundation for subsequent energy storage and power management modules.

[0053] Based on the above embodiments, the rectifier boost module includes a Zener diode, the input terminal of which is connected to the output terminal of the rectifier diode, and the output terminal of which is connected to the input terminal of the power control module. This is used to limit the DC power output by the rectifier diode and supply the controlled DC voltage to the energy storage module.

[0054] In this embodiment, the rectifier boost module is used to rectify the AC radio frequency signal received by the NFC antenna circuit into a stable DC high voltage output, and includes a bridge rectifier structure and a voltage regulation protection circuit.

[0055] Specifically, the rectifier boost module includes two RF input ports, RF1 and RF2, which are connected to the two output terminals of the NFC antenna circuit, respectively, to receive 13.56MHz RF AC signals. These signals are then input to a rectifier diode array consisting of four diodes, D1, D2, D3, and D4, forming a full-wave bridge rectifier structure. RF1 and RF2 are connected to the input terminals of D1 / D4 and D2 / D3, respectively. The positive terminal of the rectified output is formed by connecting the output terminals of D1 and D2 together, while the negative terminal is formed by connecting the output terminals of D3 and D4 together and grounding. This rectifier circuit effectively rectifies the dual-ended RF input signal into a stable unidirectional DC voltage.

[0056] To prevent the rectified output voltage from becoming too high due to energy accumulation, the rectifier boost module also includes a Zener diode, D5, with its anode connected to the negative terminal of the rectified output and its cathode connected to the positive terminal. When the rectified output voltage exceeds the Zener diode's voltage regulation threshold, D5 conducts to release excess energy, thereby limiting the output voltage to the set value and providing overvoltage protection.

[0057] Furthermore, the output of the rectifier-boost module is connected to the input of the power control module. The power control module includes a controlled-on main switching transistor Q1, used to selectively feed the rectified output into the energy storage module. After voltage regulation and protection, the rectified output, controlled by the power control module's on / off state, provides a charging path to multiple parallel energy storage capacitors, completing the temporary storage of electrical energy. In this embodiment, the rectifier-boost module not only completes the energy conversion from radio frequency signal to DC voltage, but also has overvoltage protection capability, ensuring that the subsequent energy storage module and DC-DC module operate within a safe voltage range, providing a reliable foundation for the system's passive power supply and energy efficiency control.

[0058] Based on the above embodiments, the energy storage module includes multiple energy storage capacitor groups connected in parallel, the multiple energy storage capacitor groups are connected to the output terminal of the power control module, and the output terminal of the multiple energy storage capacitor groups is connected to the input terminal of the DC-DC buck module.

[0059] When the NFC antenna receives a valid radio frequency signal, the rectifier boost module converts it into a stable high DC voltage. With the power control module on, the rectified voltage is introduced into the energy storage module, and multiple parallel capacitors begin charging and storing energy. As the voltage gradually rises to a set threshold, the energy storage module has sufficient charge to provide a continuous and stable power input to the subsequent DC-DC buck module. During DC-DC operation, the energy storage capacitors slowly discharge, releasing energy to the subsequent circuitry to ensure smooth operation of screen refresh and other functions.

[0060] In this embodiment, the energy storage circuit is used to temporarily store the DC power output from the rectifier boost module and provide a stable input voltage for the subsequent DC-DC buck module. The energy storage circuit includes a capacitor bank consisting of multiple capacitors connected in parallel, with one end of each capacitor connected to the positive terminal and the other end grounded. Specifically, the capacitor bank includes C6, C7, C8, C9, C10, C11, C12, C13, C14, and C15. Each capacitor in the capacitor bank is a surface-mount capacitor with a withstand voltage greater than the maximum value of the rectified output, and the capacitance is generally between 10μF and 47μF. Multiple capacitors are connected in parallel to improve the overall equivalent capacitance and filtering effect. The positive terminals of the multiple capacitors are connected to the output terminal of the power control module (Q1) through wires, that is, the rectified output voltage flows into the energy storage circuit after being controlled to conduct. The negative terminals are connected to the system ground terminal.

[0061] With the rectifier boost module output active and the power control module on, the input DC voltage is quickly stored in the capacitor bank. After the DC-DC buck module starts working, it serves as its input power supply, providing a continuous and stable high-voltage DC input to support the buck output for inkjet printing. Due to the capacitor's excellent charge / discharge response speed and ripple resistance, this energy storage structure not only serves as a power supply but also acts as a system voltage stabilizer. By using parallel connection to increase the equivalent capacitance and reduce the equivalent series resistance, the voltage holding capability can be effectively improved to meet the instantaneous current requirements during inkjet printing.

[0062] Furthermore, the input terminal of the DC-DC step-down module is connected to the output terminal of the energy storage module, and the output terminal is connected to the e-ink screen driver interface;

[0063] The DC-DC step-down module includes an enable control terminal EN. When the voltage of the energy storage capacitor bank is lower than a set threshold, the DC-DC step-down module shuts down to enable automatic power-off after the image is completed.

[0064] The DC-DC step-down module includes:

[0065] The DCDC chip has its input terminal connected to the output terminal of the energy storage module, and its output terminal connected to the input terminal of the e-ink screen driver interface.

[0066] An inductor, one end of which is connected to the switching output pin of the DC-DC chip, and the other end of which is connected to the output node of the buck module;

[0067] Multiple parallel-connected output filter capacitors are electrically connected to the output node to smooth the output voltage.

[0068] A voltage divider resistor is connected at one end to the output node and at the other end to the feedback pin of the step-down chip to form a closed-loop regulation of the output voltage.

[0069] The DC-DC chip includes an enable control pin, which is connected to the output terminal of the automatic power-off module.

[0070] The automatic power-off module is used to monitor the voltage of the energy storage module. When the energy storage voltage is detected to be lower than a preset threshold, it outputs a shutdown control signal to the enable control pin so that the DC-DC chip shuts down.

[0071] In this embodiment, the DC-DC buck module is used to convert the high voltage output by the energy storage module into a low voltage suitable for the operation of the e-ink screen and to provide a stable power output. The module adopts a synchronous rectification buck structure, which includes a DC-DC chip, an inductor, an output filter capacitor, a feedback resistor network, and enable control logic. The input terminal of the synchronous rectification buck chip is electrically connected to the output terminal of the energy storage module to receive the DC power supply voltage from the energy storage capacitor bank. The output terminal of the DC-DC chip is connected to one end of the inductor through a switching pin (LX pin), and the other end of the inductor is connected to the output node DCOUT of the buck module, forming a basic buck energy transmission path. The output node is further connected in parallel with filter capacitors C17 and C18 to smooth the pulsed output current into a stable DC voltage. The parallel connection of multiple capacitors effectively improves filtering performance, reduces output ripple, and enhances voltage response. To achieve closed-loop voltage regulation, a pair of series-connected voltage divider resistors R5 and R6 are also connected to the output node. One end of one resistor is connected to the output node, and the other end of the other resistor is grounded. The voltage divider between them is connected to the feedback pin (FB pin) of the buck converter chip. This structure allows the chip to detect the output voltage in real time and compare it with the internal reference voltage, dynamically adjusting the PWM duty cycle to keep the output voltage stable at a preset value. In addition, to control the start and stop of the chip, the buck converter chip has an enable control terminal (EN pin), which is connected to the main control signal line or the output terminal of the automatic power-off module. By default, the chip starts when the EN pin is high. If the automatic power-off module detects that the energy storage voltage is lower than the set threshold, it can output a low level to the EN pin, thereby shutting down the chip and entering standby mode. Through the structural design of this embodiment, the DC-DC buck converter module not only achieves efficient and stable voltage conversion, but also has controllable start-up, automatic power-off, and multi-voltage output capabilities, making it suitable for the power supply needs of different types of e-ink screens and a key energy regulation module in the system.

[0072] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the content of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. An e-ink screen circuit based on NFC passive driving, characterized in that, include: NFC antenna circuit, used to receive radio frequency signals; The rectifier boost module, electrically connected to the NFC antenna circuit, is configured to rectify the radio frequency signal into a DC signal. The energy storage module is electrically connected to the output terminal of the rectifier boost module; The power control module has its input terminal electrically connected to the output terminal of the rectifier boost module, and its output terminal connected to the energy storage module circuit. The DC-DC step-down module has its input terminal electrically connected to the energy storage module and its output terminal connected to the e-ink screen driver interface. When the power control module is turned on, the energy storage module is electrically connected to the input terminal of the DC-DC step-down module, which is used to step down the output voltage of the energy storage module to a driving voltage within a preset range.

2. The e-ink screen circuit based on NFC passive driving according to claim 1, characterized in that, It also includes an automatic power-off module, the input of which is electrically connected to the energy storage module. The automatic power-off module triggers the DC-DC step-down module through the energy storage module to shut down the output of the EN pin of the DC-DC step-down module.

3. The e-ink screen circuit based on NFC passive driving according to claim 1, characterized in that, The rectifier boost module includes an RF input port and multiple rectifier diodes. The RF input port is electrically connected to the NFC antenna circuit, and the input terminals of the multiple rectifier diodes are respectively electrically connected to the RF input port. The output terminals of the rectifier diodes respectively constitute the positive and negative DC terminals.

4. The e-ink screen circuit based on NFC passive driving according to claim 3, characterized in that, The rectifier boost module includes a Zener diode, the input terminal of which is connected to the output terminal of the rectifier diode, and the output terminal of which is connected to the input terminal of the power control module. This Zener diode is used to limit the DC power output by the rectifier diode and supply the controlled DC voltage to the energy storage module.

5. The e-ink screen circuit based on NFC passive driving according to claim 4, characterized in that, The energy storage module includes multiple energy storage capacitor groups connected in parallel. The multiple energy storage capacitor groups are connected to the output terminal of the power control module, and the output terminal of the multiple energy storage capacitor groups is connected to the input terminal of the DC-DC step-down module.

6. The e-ink screen circuit based on NFC passive driving according to claim 5, characterized in that, The input terminal of the DC-DC step-down module is connected to the output terminal of the energy storage module, and the output terminal is connected to the e-ink screen driver interface. The DC-DC step-down module includes an enable control terminal EN. When the voltage of the energy storage capacitor bank is lower than a set threshold, the DC-DC step-down module shuts down to enable automatic power-off after the image is completed.

7. The e-ink screen circuit based on NFC passive driving according to claim 2, characterized in that, The DC-DC step-down module includes: The DCDC chip has its input terminal connected to the output terminal of the energy storage module, and its output terminal connected to the input terminal of the e-ink screen driver interface. An inductor, one end of which is connected to the switching output pin of the DC-DC chip, and the other end of which is connected to the output node of the buck module; Multiple parallel-connected output filter capacitors are electrically connected to the output node to smooth the output voltage. A voltage divider resistor is connected at one end to the output node and at the other end to the feedback pin of the DC-DC chip to form a closed-loop regulation of the output voltage.

8. The e-ink screen circuit based on NFC passive driving according to claim 7, characterized in that, The DC-DC chip includes an enable control pin, which is connected to the output terminal of the automatic power-off module. The automatic power-off module is used to monitor the voltage of the energy storage module. When the energy storage voltage is detected to be lower than a preset threshold, it outputs a shutdown control signal to the enable control pin so that the DC-DC chip shuts down.

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