Electronic paper display device and its feed protection and charging optimization method

Abstract

The application discloses an electronic paper display device and a power feeding protection and charging optimization method thereof, and belongs to the technical field of display devices.The electronic paper display device comprises an electronic paper screen, an energy storage unit for storing electric energy, an ambient light energy collection module for converting ambient light into electric energy and providing the electric energy to a power management module, the power management module for managing the storage and distribution of the electric energy and outputting a first voltage signal representing real-time electric quantity of the energy storage unit and a current signal representing real-time charging current size to a master control module, a display driving module for driving the electronic paper screen to refresh a picture, a power supply circuit of the display driving module being controlled by the master control module, and the master control module for receiving the first voltage signal and the current signal and generating a control instruction according to a comparison result of the real-time electric quantity and a first electric quantity threshold value and a comparison result of the real-time charging current size and a first current threshold value.The application solves the problems that the electronic paper is prone to display abnormalities during power feeding, charging is slow and automatic recovery is impossible, and realizes energy autonomy and high-reliability operation.

Description

Technical Field

[0001] This invention relates to the field of electronic paper display technology, and in particular to an electronic paper display device and its power supply protection and charging optimization method. Background Technology

[0002] Common electronic paper technologies include electrophoretic display (microcup / capsule ball technology) and cholesteric liquid crystal display technology.

[0003] To further expand the application of electronic paper in environments without a stable mains power supply, the industry generally adopts a solution that combines electronic paper with photovoltaic technology. Specifically, ambient light energy collection devices, such as micro-light-collecting films, are typically integrated on the back of the electronic paper screen, along with energy storage units (such as batteries or supercapacitors) and power management circuitry, forming a self-powered system. This solution aims to use ambient light to charge the device, theoretically enabling "one-time deployment, long-term operation," significantly reducing wiring costs and maintenance frequency, and improving deployment flexibility.

[0004] However, existing "electronic paper + photovoltaic" systems still face a significant technical challenge in practical applications: under conditions such as continuous rain, nighttime, or severe indoor lighting deficiency, the ambient light energy harvesting module cannot generate enough electrical energy, leading to the gradual depletion of the energy storage unit's power (i.e., "power feeding"). Current mainstream solutions have the following inherent defects when power feeding occurs:

[0005] Abnormal interruption of display process: When the system suddenly loses power during the screen refresh process (i.e., "image refresh"), the driving voltage drops, which can easily lead to incomplete screen refresh, display ghosting, garbled text, or screen distortion, seriously affecting the viewing experience and information transmission.

[0006] The system is "deadlocked" and cannot recover on its own: Power outages not only cause display abnormalities, but more commonly, they cause the system's main control unit or display driver module to reset or crash due to insufficient voltage. Once the lighting conditions are restored and the energy storage unit starts charging again, the system often cannot automatically recover from the abnormal state to the normal display cycle, requiring manual intervention. This contradicts the original design intention of "unattended operation" and greatly limits its reliability.

[0007] Low charging recovery efficiency: In situations of low power and weak light, existing systems lack proactive coping strategies. If the system is completely shut down, it cannot utilize weak light energy; if the system attempts to maintain operation, energy consumption may exceed energy collection, creating a vicious cycle. Even when some system functions are in sleep mode, if the e-paper screen remains on any previous image, its low light transmittance will block the light collection module behind it, severely limiting charging efficiency and causing the system to remain in a stagnant state of "low power - unable to charge - unable to start" for extended periods. Summary of the Invention

[0008] To address the technical problems existing in the background art, this invention proposes an electronic paper display device and its power supply protection and charging optimization method.

[0009] The present invention provides an electronic paper display device, comprising:

[0010] Electronic paper screen;

[0011] Energy storage units are used to store electrical energy;

[0012] An ambient light energy acquisition module is used to convert ambient light into electrical energy and supply it to the power management module;

[0013] The power management module is used to manage the storage and distribution of electrical energy, and outputs a first voltage signal representing the real-time power of the energy storage unit and a current signal representing the real-time charging current to the main control module.

[0014] The display driver module is used to drive the electronic paper screen to refresh the image, and its power supply circuit is controlled by the main control module.

[0015] The main control module is used to receive the first voltage signal and the current signal, and generate control commands based on the comparison results of the real-time power level and the first power level threshold, and the comparison results of the real-time charging current and the first current threshold.

[0016] When the real-time battery level is lower than the first battery threshold and the real-time charging current is greater than the first current threshold, the main control module generates a first control command to control the display driver module to power off and lock its display screen.

[0017] When the real-time battery level is lower than the first battery level threshold and the real-time charging current is less than or equal to the first current threshold, the main control module generates a second control command to control the electronic paper screen to refresh to a completely black screen and control the display driver module to power off after the refresh is completed.

[0018] The main control module is also used to continuously monitor the real-time power level after the display driver module is powered off, and generate a recovery command to restore the power supply to the display driver module and the normal display process when the real-time power level rises above the second power threshold. The second power threshold is greater than the first power threshold.

[0019] Preferably, the power management module includes a sampling unit and a switch control unit; wherein, the sampling unit is used to collect the voltage of the energy storage unit and the charging current of the ambient light energy acquisition module to generate a first voltage signal and a current signal; the switch control unit is connected in series in the power supply circuit of the display driver module, and the control terminal of the switch control unit is connected to the main control module to receive control commands and recovery commands.

[0020] Preferably, the energy storage unit includes a supercapacitor.

[0021] Preferably, the main control module receives a first voltage signal through a first general-purpose input / output port, receives a current signal through a second general-purpose input / output port, and outputs a switching control signal for the power supply circuit of the display driver module through a third general-purpose input / output port.

[0022] Preferably, the main control module is connected to the display driver module via an I2C communication interface, and is used to send screen refresh commands and receive status feedback.

[0023] Preferably, the ambient light energy acquisition module is a micro-light energy film.

[0024] Preferably, the electronic paper screen is a cholesteric liquid crystal screen, and the all-black image corresponds to the focal cone state of the cholesteric liquid crystal screen.

[0025] Preferably, the ambient light energy acquisition module is attached to the back of the electronic paper screen.

[0026] The present invention proposes a power supply protection and charging optimization method for electronic paper display devices, applicable to any of the electronic paper display devices described above, the method comprising the following steps:

[0027] Acquire the first voltage signal characterizing the real-time power of the energy storage unit and the current signal characterizing the real-time charging current of the ambient light energy acquisition module.

[0028] Compare the real-time battery level with a first battery threshold and compare the real-time charging current with a first current threshold.

[0029] When the real-time battery level is lower than the first battery level threshold and the real-time charging current is greater than the first current threshold, the control display driver module is powered off and the current display screen is latched.

[0030] When the real-time battery level is lower than the first battery threshold and the real-time charging current is less than or equal to the first current threshold, control the electronic paper screen to refresh to a completely black screen and control the display driver module to power off after the refresh is completed.

[0031] The real-time power level is continuously monitored after the display driver module is powered off.

[0032] When the real-time power level is detected to rise above the second power threshold, the power supply to the display driver module is restored and the normal display process is started; wherein, the second power threshold is greater than the first power threshold.

[0033] Preferably, after comparing the real-time battery level with a first battery level threshold and comparing the real-time charging current with a first current threshold, the method further includes: when the real-time battery level is higher than or equal to the first battery level threshold, controlling the display driver module to maintain a normal loop screen refresh process.

[0034] This invention proposes an electronic paper display device and its power supply protection and charging optimization method. Through the main control module's coordinated monitoring and intelligent judgment of power and charging current, it achieves adaptive switching of the display control strategy under power supply failure conditions. When lighting is adequate, the screen is latched to conserve energy; when lighting is weak, the screen is actively blacked out to maximize light transmittance and charging efficiency; and the display is automatically restarted after power is restored. This avoids display anomalies caused by power supply failure, improves energy harvesting speed and system endurance in low-light environments, ensures high reliability and self-recovery capability under unattended conditions, and greatly optimizes the user experience and application value of photovoltaic electronic paper products in complex lighting environments such as outdoors. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the system architecture of an electronic paper display device proposed in this invention;

[0036] Figure 2 This is a schematic diagram of the circuit architecture of one embodiment of an electronic paper display device proposed in this invention;

[0037] Figure 3 This is a schematic diagram illustrating the workflow of one embodiment of the electronic paper display device proposed in this invention;

[0038] Figure 4 This is a flowchart illustrating the power supply protection and charging optimization method for an electronic paper display device proposed in this invention. Detailed Implementation

[0039] Reference Figures 1-4 The present invention provides an electronic paper display device, comprising:

[0040] Electronic paper screen;

[0041] Specifically, the electronic paper screen is a cholesteric liquid crystal screen, and a completely black screen corresponds to the focal cone state of the cholesteric liquid crystal screen.

[0042] In this embodiment, the ambient light energy acquisition module is attached to the back of the electronic paper screen.

[0043] Energy storage unit, used to store electrical energy.

[0044] In this embodiment, the energy storage unit includes a supercapacitor.

[0045] Specifically, the positive and negative terminals of the supercapacitor are connected to the energy storage terminals of the power management module to store the electrical energy converted from the ambient light energy harvesting module. Supercapacitors are characterized by fast charging and discharging speeds and long cycle life, making them suitable for use in photovoltaic systems with intermittent sunlight.

[0046] The ambient light energy acquisition module is used to convert ambient light into electrical energy and supply it to the power management module.

[0047] In this embodiment, the ambient light energy acquisition module is a micro-light energy film.

[0048] Specifically, the low-light-energy film is attached to the back of the electronic paper screen, particularly the back of a cholesteric liquid crystal screen. The positive and negative terminals of the low-light-energy film are connected to the charging input of the power management module. The low-light-energy film converts ambient light shining on the screen into electrical energy, where ambient light includes indoor lighting and natural light.

[0049] The power management module is used to manage the storage and distribution of electrical energy, and outputs a first voltage signal representing the real-time power of the energy storage unit and a current signal representing the real-time charging current to the main control module.

[0050] In this embodiment, the power management module includes a sampling unit and a switch control unit; wherein, the sampling unit is used to collect the voltage of the energy storage unit and the charging current of the ambient light energy collection module to generate a first voltage signal and a current signal; the switch control unit is connected in series in the power supply circuit of the display driver module, and the control terminal of the switch control unit is connected to the main control module to receive control commands and recovery commands.

[0051] Specifically, the sampling unit consists of a high-precision sampling resistor network (such as resistors R1 and R2) and a signal conditioning circuit. One sampling branch is connected across the energy storage unit, specifically across the supercapacitor, to acquire the voltage across its terminals and generate a first voltage signal suitable for the read range of the main control module's ADC (analog-to-digital converter) through voltage division. This first voltage signal is linearly related to the charge quantity of the supercapacitor (i.e., the real-time charge). The other sampling branch is connected in series in the charging circuit of the ambient light energy acquisition module to acquire the charging current and convert it into a current signal output. The sampling unit connects the first voltage signal and the current signal to designated GPIO ports of the main control module.

[0052] Specifically, such as Figure 2 As shown, the switch control unit in this embodiment uses a MOSFET as a power switch. Its source is connected to the positive terminal of the energy storage unit, its drain is connected to the power input terminal of the display driver module, and its gate is connected to a GPIO port (e.g., GPIO3) of the main control module through a current-limiting resistor. The main control module controls the conduction and cutoff of the MOSFET by outputting a high or low level to this port, thereby realizing the on / off control of the power supply circuit of the display driver module.

[0053] The display driver module is used to drive the electronic paper screen to refresh the image, and its power supply circuit is controlled by the main control module.

[0054] Specifically, the display driver module is the motherboard of the electronic paper device. It connects to the electronic paper screen via a flexible printed circuit board (FPC) and is responsible for generating drive waveforms to refresh the screen display content. Its power supply comes from the output of the switch control unit. In addition, the display driver module has an I2C slave interface for communicating with the master control module, receiving specific commands such as "swipe black", and providing feedback on the command execution status.

[0055] The main control module is used to receive the first voltage signal and the current signal, and generate control commands based on the comparison results of the real-time power level and the first power level threshold, as well as the comparison results of the real-time charging current and the first current threshold.

[0056] Specifically, when the real-time battery level is lower than the first battery level threshold and the real-time charging current is greater than the first current threshold, the main control module generates a first control command to control the display driver module to power off and lock its display screen.

[0057] When the real-time battery level is lower than the first battery level threshold and the real-time charging current is less than or equal to the first current threshold, the main control module generates a second control command to control the electronic paper screen to refresh to a completely black screen and to control the display driver module to power off after the refresh is completed.

[0058] The main control module is also used to continuously monitor the real-time power level after the display driver module is powered off, and generate a recovery command to restore the power supply to the display driver module and the normal display process when the real-time power level rises above the second power threshold. The second power threshold is greater than the first power threshold.

[0059] In this embodiment, the main control module receives a first voltage signal through the first general-purpose input / output port, receives a current signal through the second general-purpose input / output port, and outputs a control signal for switching the power supply circuit of the display driver module through the third general-purpose input / output port.

[0060] Specifically, the main control module connects to the display driver module via an I2C communication interface to send screen refresh commands and receive status feedback.

[0061] Specifically, such as Figure 2 As shown, the main control module (MCU) uses a low-power microcontroller. Its hardware connections include:

[0062] Configure the first general purpose input / output port (GPIO1) as an ADC input, connect it to the first voltage signal sent by the sampling unit, and periodically read the real-time power of the energy storage unit.

[0063] Configure the second general purpose input / output port (GPIO2) as an ADC input, connect it to the current signal sent by the sampling unit, and read the real-time charging current magnitude.

[0064] Configured as a digital output via the third general purpose input / output port (GPIO3), it is connected to the gate of the switch control unit (MOSFET) to output on / off control signals.

[0065] It connects to the I2C interface of the display driver module via the I2C communication interface (SCL, SDA) to send control commands and receive status feedback.

[0066] The MCU's internal firmware stores a preset first power threshold (e.g., corresponding to a supercapacitor voltage of 3.1V, approximately 15% power), a second power threshold (e.g., corresponding to a voltage of 3.3V, approximately 30% power), and a first current threshold (e.g., 5mA).

[0067] The system's workflow, combined with Figure 3 The flowchart shown illustrates the system implementation process, which includes:

[0068] (1) System initialization and status monitoring

[0069] After the device is powered on, the main control module MCU starts up and initializes the various general purpose input / output ports (GPIO) and I2C interfaces. The MCU first reads the first voltage signal through GPIO1 and calculates the current real-time power level.

[0070] (2) Normal display status

[0071] If the calculated real-time battery level is higher than the first battery threshold (e.g., >15%), the MCU determines that the system is in normal display mode. At this time, the MCU outputs a low level via GPIO3, turning on the MOSFET of the switch control unit to supply power to the display driver module. The display driver module refreshes the screen content (such as advertising images, price tag information, etc.) according to a predetermined process. After each refresh command is executed, the display driver module sends a "refresh complete" status message back to the MCU via I2C. Upon receiving this status, the MCU immediately samples the first voltage signal again via GPIO1 to perform a new round of battery level checks, forming a closed-loop control.

[0072] (3) Power supply status judgment and differentiation processing

[0073] When the MCU detects that the real-time battery level is lower than the first battery threshold, the system enters the power supply process. At this time, the MCU synchronously reads the current signal through GPIO2 to obtain the real-time charging current magnitude.

[0074] Scenario A (First Power Supply State): If the real-time charging current is greater than the first current threshold (e.g., >5mA), it indicates that the ambient light is relatively sufficient and there is still an effective charging current. The MCU then generates the first control instruction, which is to output a high level through GPIO3 to turn off the MOSFET, thereby disconnecting the power supply to the display driver module.

[0075] Because electronic paper has bistable properties, when power is cut off, the screen will latch and remain on the last displayed frame, without consuming any power. The system enters a "keep display, silently charge" mode.

[0076] Scenario B (Second Power Supply State): If the real-time charging current is less than or equal to the first current threshold (e.g., ≤5mA), it indicates that the ambient light is very weak and the charging efficiency is extremely low. The MCU then generates a second control instruction. The execution of this second control instruction consists of two sub-steps:

[0077] To refresh the screen to black: The MCU first ensures that the switch control unit is in the ON state (if it is OFF, turn it ON first), and then sends a "refresh to black" command to the display driver module via the I2C interface. After receiving the command, the display driver module drives the e-paper screen to refresh a completely black image.

[0078] Power-off standby: After the display driver module completes the black-out operation and sends a "command execution completed" message to the MCU via I2C, the MCU immediately outputs a high level through GPIO3 to turn off the MOSFET and disconnect the power supply to the display driver module. At this time, the screen remains completely black.

[0079] For cholesteric liquid crystal displays, a completely black screen corresponds to its focal conic (FC) state, in which liquid crystal molecules are arranged in a multi-domain configuration, resulting in the highest light transmittance. This allows the back-mounted micro-light-emitting film to receive the maximum amount of transmitted light, thereby maximizing charging efficiency.

[0080] (4) Charging recovery monitoring

[0081] In both scenario A and scenario B, after the display driver module is powered off, the system enters a low-power monitoring mode. The MCU itself enters an intermittent wake-up state to reduce power consumption. The MCU wakes up periodically (e.g., every minute) to sample the first voltage signal through GPIO1 and continuously monitor the real-time power of the energy storage unit.

[0082] (5) Automatically restore display

[0083] When the MCU detects that the real-time power level has risen above the second power threshold (e.g., >30%), it indicates that the energy storage unit has stored enough energy for the next complete display cycle. The MCU then generates a recovery instruction, which includes: first, outputting a low level through GPIO3 to turn on the MOSFET and restore power to the display driver module. After the display driver module is powered on and initialized, the MCU then notifies it via I2C to start executing the normal display refresh process. The system thus automatically recovers to the normal display state described in step (1), forming a complete and autonomous "display-power protection-charging-recovery" closed loop.

[0084] Reference Figures 1-4 The present invention proposes a power supply protection and charging optimization method for electronic paper display devices, applicable to any of the above-mentioned electronic paper display devices, the method comprising the following steps:

[0085] Acquire the first voltage signal characterizing the real-time power of the energy storage unit and the current signal characterizing the real-time charging current of the ambient light energy acquisition module.

[0086] Compare the real-time battery level with a first battery threshold and compare the real-time charging current with a first current threshold.

[0087] When the real-time battery level is lower than the first battery level threshold and the real-time charging current is greater than the first current threshold, the control display driver module is powered off and the current display screen is latched.

[0088] When the real-time battery level is lower than the first battery threshold and the real-time charging current is less than or equal to the first current threshold, control the electronic paper screen to refresh to a completely black screen and control the display driver module to power off after the refresh is completed.

[0089] Continuously monitor the real-time power level after the display driver module is powered off;

[0090] When the real-time power level is detected to rise above the second power threshold, the power supply to the display driver module is restored and the normal display process is started; wherein, the second power threshold is greater than the first power threshold.

[0091] In this embodiment, after comparing the real-time battery level with a first battery level threshold and comparing the real-time charging current with a first current threshold, the method further includes: when the real-time battery level is higher than or equal to the first battery level threshold, controlling the display driver module to maintain a normal loop screen refresh process.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An electronic paper display device, characterized in that, include: Electronic paper screen; Energy storage units are used to store electrical energy; An ambient light energy acquisition module is used to convert ambient light into electrical energy and supply it to the power management module; The power management module is used to manage the storage and distribution of electrical energy, and outputs a first voltage signal representing the real-time power of the energy storage unit and a current signal representing the real-time charging current to the main control module. The display driver module is used to drive the electronic paper screen to refresh the image, and its power supply circuit is controlled by the main control module. The main control module is used to receive the first voltage signal and the current signal, and generate control commands based on the comparison results of the real-time power level and the first power level threshold, and the comparison results of the real-time charging current and the first current threshold. When the real-time battery level is lower than the first battery threshold and the real-time charging current is greater than the first current threshold, the main control module generates a first control command to control the display driver module to power off and lock its display screen. When the real-time battery level is lower than the first battery level threshold and the real-time charging current is less than or equal to the first current threshold, the main control module generates a second control command to control the electronic paper screen to refresh to a completely black screen and control the display driver module to power off after the refresh is completed. The main control module is also used to continuously monitor the real-time power level after the display driver module is powered off, and generate a recovery command to restore the power supply to the display driver module and the normal display process when the real-time power level rises above the second power threshold. The second power threshold is greater than the first power threshold. The power management module includes a sampling unit and a switch control unit; wherein, the sampling unit is used to collect the voltage of the energy storage unit and the charging current of the ambient light energy collection module to generate a first voltage signal and a current signal; the switch control unit is connected in series in the power supply circuit of the display driver module, and the control terminal of the switch control unit is connected to the main control module to receive control commands and recovery commands; The main control module receives a first voltage signal through a first general-purpose input / output port, receives a current signal through a second general-purpose input / output port, and outputs a switching control signal for the power supply circuit of the display driver module through a third general-purpose input / output port. The main control module is connected to the display driver module via an I2C communication interface, and is used to send screen refresh commands and receive status feedback.

2. The electronic paper display device according to claim 1, characterized in that, The energy storage unit includes a supercapacitor.

3. The electronic paper display device according to claim 1, characterized in that, The ambient light energy acquisition module is a micro-light energy film.

4. The electronic paper display device according to claim 1, characterized in that, The electronic paper screen is a cholesteric liquid crystal screen, and the all-black image corresponds to the focal cone state of the cholesteric liquid crystal screen.

5. The electronic paper display device according to claim 1, characterized in that, The ambient light energy acquisition module is attached to the back of the electronic paper screen.

6. A method for power supply protection and charging optimization of an electronic paper display device, characterized in that, Applied to the electronic paper display device according to any one of claims 1-5, the method includes the following steps: Acquire the first voltage signal characterizing the real-time power of the energy storage unit and the current signal characterizing the real-time charging current of the ambient light energy acquisition module. Compare the real-time battery level with a first battery threshold and compare the real-time charging current with a first current threshold. When the real-time battery level is lower than the first battery level threshold and the real-time charging current is greater than the first current threshold, the control display driver module is powered off and the current display screen is latched. When the real-time battery level is lower than the first battery threshold and the real-time charging current is less than or equal to the first current threshold, control the electronic paper screen to refresh to a completely black screen and control the display driver module to power off after the refresh is completed. The real-time power level is continuously monitored after the display driver module is powered off. When the real-time power level is detected to rise above the second power threshold, the power supply to the display driver module is restored and the normal display process is started; wherein, the second power threshold is greater than the first power threshold.

7. The power supply protection and charging optimization method for electronic paper display devices according to claim 6, characterized in that, After comparing the real-time battery level with a first battery level threshold and comparing the real-time charging current with a first current threshold, the method further includes: when the real-time battery level is higher than or equal to the first battery level threshold, controlling the display driver module to maintain a normal loop screen refresh process.

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