A backlight method, system, device and storage medium applied to an ink screen

Abstract

The application relates to a backlight method, system, device and storage medium applied to a water ink screen, in particular to the display and backlight control technical field of the water ink screen. The application collects a timing reference signal of a display driving link of the water ink screen, a real-time brightness feedback signal of a photoelectric sensor and a state parameter of real-time use of a user, and adjusts the corresponding backlight intensity in real time. The timing reference signal is used as a synchronous clock reference to drive the backlight intensity to switch, so that the power switching edge and the working stage edge are phase-aligned, and the deviation is corrected through the real-time brightness feedback signal. The application solves the problems that the backlight system of the water ink screen is independent of the display timing operation, the static stage power consumption ratio is high, the brightness control progress is insufficient, and the scene adaptability is poor, guarantees the picture refreshing quality, significantly reduces the average power consumption of the backlight, improves the control precision and the user experience, and is suitable for various water ink screen intelligent terminals.

Description

Technical Field

[0001] This invention relates to the field of e-ink display and backlight control technology, and particularly to a backlight method, system, device and storage medium for e-ink displays. Background Technology

[0002] E-ink display devices with front backlights have become the mainstream in fields such as e-reading, smart retail, and wearable terminals due to their core advantages of bistable zero power consumption, paper-like display experience, and low visual fatigue during long-term reading. However, existing backlight control technologies generally rely on open-loop control frameworks independent of display drivers, which presents technical bottlenecks that are difficult to overcome.

[0003] Conventional phased dimming solutions suffer from a significant drop in synchronization accuracy in complex scenarios such as frequent partial screen refreshes and alternating refresh modes. Furthermore, they cannot distinguish the optical characteristics and power consumption requirements of different refresh stages, and can only achieve globally uniform level-based brightness switching, failing to meet the core requirement of precise adaptation between backlight and display timing.

[0004] Meanwhile, existing technologies suffer from poor tracking stability of screen refresh status, brightness output is easily affected by device temperature drift and optical component aging and degradation, and manual dimming is inconvenient in dynamic reading scenarios, severely impacting the actual user experience of e-ink screen devices. Figure 6 As shown, existing e-ink screen backlight devices generally adopt an independent backlight control architecture, which cannot coordinate with the display refresh timing, and is a typical manifestation of the above-mentioned technical defects. Summary of the Invention

[0005] This invention discloses a method, system, device, and storage medium for backlighting an e-ink screen. Relying on the driving timing stage identifier and dual-stage energy efficiency adaptation characteristics, it adopts a dimming system that combines phase-aligned synchronous driving with deviation correction to optimize the synchronization accuracy and brightness stability of traditional open-loop backlighting, thereby achieving precise refresh edge alignment, staged energy efficiency control, and low-cost, large-scale application of general-purpose hardware.

[0006] To achieve the above objectives, the present invention provides a backlighting method for use with e-ink screens, comprising the following steps: The timing reference signal of the e-ink screen driving link and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side are collected. The timing reference signal is used to identify the timing state of screen refresh, and the real-time brightness feedback signal is used to identify the actual effective brightness of the backlight illuminating the e-ink screen. The timing reference signal is analyzed to identify the current working stage of the e-ink screen, and the target backlight intensity parameter corresponding to the current working stage is generated by matching a preset mapping relationship. The working stage includes a dynamic refresh stage and a steady-state maintenance stage. A drive control signal is generated based on the target backlight intensity parameter. The timing reference signal is used as the synchronization clock reference. After the switching edge of the drive control signal is phase-aligned with the switching edge of the current working stage, the drive control signal is output to the backlight drive unit to drive the light module to adjust to the target backlight intensity. The brightness deviation is calculated based on the real-time brightness feedback signal and the target backlight intensity parameter, a deviation correction amount is generated, and the driving control signal is finely adjusted in reverse to converge the actual backlight brightness to the target backlight intensity.

[0007] Further, the timing reference signal of the e-ink screen driving link is acquired, including the following steps: Connect the busy signal pin of the e-ink screen driver chip to the general-purpose input / output pin of the microcontroller, configure the general-purpose input / output pin to input mode, and enable double-edge external interrupts. The microcontroller sends screen refresh commands to the e-ink screen driver chip via the communication bus and monitors the level changes of the busy signal in real time. When the busy signal is detected to transition from low to high, a rising edge interrupt is triggered, and the current system timestamp is recorded as the refresh start time. Simultaneously, the refresh status flag is set to 1. When the busy signal is detected to change from high to low, a falling edge interrupt is triggered and the current system timestamp is recorded as the refresh end time, while the refresh status flag is cleared to zero. The continuous level state of the busy signal, the refresh start time, and the refresh end time together constitute the timing reference signal, and the refresh status flag is used to identify the current working stage of the e-ink screen.

[0008] Further, the timing reference signal is analyzed to identify the current working stage of the e-ink screen, and the target backlight intensity parameters corresponding to the current working stage are generated by matching, including the following steps: The microcontroller parses the timing reference signal, updates the bit value of the internal refresh status flag, and records the current system timestamp. When the refresh status flag has a bit value of 1, it is determined that the current state is in the dynamic refresh stage. The microcontroller generates a first target backlight intensity parameter by matching a preset first mapping relationship. The first target backlight intensity parameter corresponds to a first brightness state. When the refresh status flag has a bit value of 0, it is determined that the current state is in a steady state maintenance phase. The microcontroller generates a second target backlight intensity parameter by matching a preset second mapping relationship. The second target backlight intensity parameter corresponds to a second brightness state. The backlight intensity in the first brightness state is higher than the backlight intensity in the second brightness state.

[0009] Further, a drive control signal is generated based on the target backlight intensity parameter. Using the timing reference signal as a synchronization clock reference, the switching edge of the drive control signal is phase-aligned with the switching edge of the current working stage, and then the drive control signal is output to the backlight driving unit to drive the light module to adjust towards the target backlight intensity. This includes the following steps: The microcontroller generates a PWM drive control signal that matches the target brightness based on the corresponding value of the target backlight intensity parameter. Extract the two working phase switching edges from the timing reference signal, including the rising edge at the start of the dynamic refresh phase and the falling edge at the steady state maintenance phase; Based on the working phase switching edge as the clock reference and the clock reference as the synchronous trigger point, the brightness switching time of the PWM drive control signal is adjusted so that the brightness rising edge of the PWM drive control signal is aligned with the starting rising edge of the dynamic refresh phase and the brightness falling edge is aligned with the starting falling edge of the steady-state maintenance phase, thus completing phase alignment. The PWM drive control signal that has completed phase alignment is output to the control input port of the backlight drive unit; The backlight driving unit converts the PWM driving control signal into power and outputs a driving current corresponding to the target backlight intensity to the optical module, thereby driving the optical module to operate stably at the target brightness state.

[0010] Further, based on the real-time brightness feedback signal and the target backlight intensity parameter, the brightness deviation is calculated, a deviation correction amount is generated, and the driving control signal is finely adjusted in reverse to converge the actual backlight brightness to the target backlight intensity, including the following steps: The actual output brightness of the light module is collected by the photoelectric sensor on the backlight output side, and the analog light sensing signal is converted into a digital signal by the analog-to-digital conversion unit to generate a real-time brightness feedback signal. The difference between the actual brightness value corresponding to the real-time brightness feedback signal and the target backlight intensity parameter is calculated to obtain the deviation value of the current brightness. Based on the magnitude and direction of the current brightness deviation value, a corresponding deviation correction amount is generated using a preset proportional-integral algorithm; The effective duty cycle parameter of the drive control signal is corrected in reverse according to the deviation correction amount, and the control command output to the backlight drive unit is updated. The brightness acquisition, deviation calculation and signal correction are executed in a loop so that the actual output brightness of the backlight gradually converges and stabilizes at the target backlight intensity.

[0011] Furthermore, the dynamic refresh phase includes full refresh mode, local refresh mode, and fast refresh mode; Different refresh modes correspond to different primary target backlight intensity parameters. The primary target backlight intensity parameter is the highest for full refresh mode, followed by partial refresh mode, and the primary target backlight intensity parameter is the lowest for fast refresh mode.

[0012] Furthermore, before triggering an external interrupt, a double-edge debouncing check is performed, specifically including: When a level change in the busy signal is detected, a pre-set anti-shake timing window is activated; Based on the continuous sampling of the busy signal level within the anti-shake timing window, if the level is stable, it is determined to be a valid transition, triggering the corresponding interrupt and recording the timestamp; If the voltage level bounces back, it is determined to be interference jitter and no interrupt is triggered.

[0013] This invention provides a backlight system for use in e-ink displays, comprising: The signal acquisition unit is used to acquire the timing reference signal of the e-ink screen driving link and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side. The timing reference signal is used to identify the timing state of screen refresh, and the real-time brightness feedback signal is used to identify the actual effective brightness of the backlight illuminating the e-ink screen. The state analysis unit is used to analyze the timing reference signal, identify the current working stage of the e-ink screen, and generate the target backlight intensity parameter corresponding to the current working stage by matching a preset mapping relationship. The working stage includes a dynamic refresh stage and a steady-state maintenance stage. The synchronous driving unit is used to generate a driving control signal according to the target backlight intensity parameter, and with the timing reference signal as the synchronous clock reference, after keeping the switching edge of the driving control signal in phase aligned with the switching edge of the current working stage, output the driving control signal to the backlight driving unit to drive the light module to adjust to the target backlight intensity. The correction unit is used to calculate the brightness deviation based on the real-time brightness feedback signal and the target backlight intensity parameter, generate the deviation correction amount, and fine-tune the driving control signal in reverse to converge the actual backlight brightness to the target backlight intensity.

[0014] The present invention also provides a backlight device for use in e-ink screens, comprising: It includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement any of the method steps described above for applying an e-ink screen.

[0015] The present invention also provides a storage medium for use in e-ink displays, wherein a computer program is stored thereon, comprising: When the computer program is executed by the processor, it implements any of the method steps described above for use with an e-ink screen.

[0016] The present invention provides a backlighting method, system, device, and storage medium for use in e-ink displays, which has the following beneficial effects: This invention effectively solves the problems of low synchronization accuracy and disconnect between brightness switching and screen refresh in traditional staged dimming schemes by establishing a phase alignment relationship between backlight brightness switching and the actual refresh timing of the e-ink screen. It achieves accurate identification of the screen's operating stage and synchronized brightness switching. Based on this, it performs multi-dimensional coordinated control of refresh mode attributes, stage timing states, optical display requirements, and dual-stage energy efficiency mapping. This effectively improves the screen contrast during dynamic refresh stages and adaptively reduces ineffective power consumption during steady-state stages. Simultaneously, proportional-integral correction ensures brightness accuracy and display consistency throughout the entire lifecycle. Combined with general-purpose driver chip pin acquisition and a standardized microcontroller control architecture, it achieves low-cost deployment without custom hardware. While retaining the original advantages of e-ink screens—bistable zero power consumption and paper-like display—it improves the display experience and overall energy efficiency of the device in low-light environments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a backlighting method applied to an e-ink screen according to an embodiment of the present invention; Figure 2 This is a system structure block diagram of a backlight system applied to an e-ink screen according to one embodiment of the present invention; Figure 3 This is a phase alignment timing comparison diagram of a backlight method applied to an e-ink screen according to an embodiment of the present invention; Figure 4 This is a comparison diagram of the brightness of a two-stage dimming method for a backlighting method applied to an e-ink screen according to an embodiment of the present invention. Figure 5 This is a schematic diagram of double-edge anti-shake verification of a backlight method applied to an e-ink screen in one embodiment of the present invention; Figure 6 A physical diagram of the application of existing technical solutions.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] Reference Figure 1This is a flowchart illustrating a backlighting method for an e-ink screen proposed in this invention, comprising the following steps: S1, collects the timing reference signal of the e-ink screen driving link and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side. The timing reference signal is used to identify the timing state of screen refresh, and the real-time brightness feedback signal is used to identify the actual effective brightness of the backlight illuminating the e-ink screen. S2, parse the timing reference signal, identify the current working stage of the e-ink screen, and generate the target backlight intensity parameter corresponding to the current working stage by matching the preset mapping relationship. The working stage includes a dynamic refresh stage and a steady-state maintenance stage. S3, generate a drive control signal according to the target backlight intensity parameter, use the timing reference signal as the synchronization clock reference, keep the switching edge of the drive control signal in phase with the switching edge of the current working stage, and output the drive control signal to the backlight drive unit to drive the light module to adjust to the target backlight intensity. S4. Calculate the brightness deviation based on the real-time brightness feedback signal and the target backlight intensity parameter, generate a deviation correction amount, and fine-tune the driving control signal in reverse to converge the actual backlight brightness to the target backlight intensity.

[0021] In one embodiment, the busy signal pin of the e-ink screen driver chip is connected to a general-purpose input / output pin of the microcontroller. This pin is configured as an input mode and enables both rising and falling edge external interrupts. The external interrupt triggering modes are configured as rising edge triggering and falling edge triggering, respectively. Both types of interrupts share the same interrupt channel, and the trigger source is distinguished by an interrupt status register. The interrupt priority is set to the second highest priority, second only to the system tick timer, ensuring that the busy signal transition can be responded to promptly, with the interrupt response delay controlled within 1 microsecond. The busy signal is a native status indication signal output by the e-ink screen driver chip. A high level indicates that the chip is performing a screen refresh operation, while a low level indicates that the refresh is complete and the screen is in a stable display state.

[0022] The microcontroller sends screen refresh commands to the e-ink screen driver chip via a communication bus and monitors the level changes of the busy signal in real time. The communication bus is a serial peripheral interface bus, with the microcontroller acting as the master and the e-ink screen driver chip as the slave, and the communication clock frequency is set to 10MHz. After the microcontroller writes screen data to the driver chip according to the display control logic and issues a refresh start command after configuring the refresh control register, it enters the busy signal monitoring state, continuously reads the level values ​​of the general-purpose input / output pins, and waits for real-time status feedback from the backlight driver chip.

[0023] Reference Figure 5A schematic diagram of a dual-edge jitter stabilization verification method for backlighting in e-ink displays. This invention distinguishes between valid jumps and interfering jitter through a fixed-duration jitter stabilization timing window. The verification logic is divided into two scenarios: The first type is a valid transition scenario: after a level transition occurs, if the level state continuously sampled within the anti-shake timing window remains stable and no rebound occurs, it is determined to be a real stage switching signal, triggering the corresponding interrupt and recording the timestamp; The second scenario is interference jitter: after a level jump, a level bounce occurs within the anti-jitter timing window, and the stable state cannot be maintained. This is determined to be a false jump caused by electromagnetic interference or power supply ripple, and no interrupt is triggered. The original working state is maintained.

[0024] When a level transition of the busy signal is detected, a double-edge debouncing check is first performed. After confirming a valid rising edge transition, a rising edge interrupt is triggered and the current system timestamp is recorded as the refresh start time. At the same time, the bit value of the refresh status flag is set to 1. When the microcontroller first detects a trend of the busy signal transitioning from low to high, it initiates a pre-set anti-jitter timing window. The default duration of the anti-jitter timing window is 5 milliseconds, which can be adjusted within the range of 1 to 10 milliseconds depending on the actual electromagnetic environment. Within the anti-jitter timing window, the system continuously samples the level of the busy signal at a high-frequency sampling rate of 100kHz. If the level remains stable at a high level without any bounce within the window, it is determined to be a valid rising edge transition, triggering a rising edge external interrupt, pausing the current main program execution, and entering the interrupt response process. During the interrupt response process, the interrupt status register is first read to confirm that this is a rising edge trigger. The current system timer count value is read, marked as the refresh start time, and stored in the corresponding register. At the same time, the value of the internally maintained refresh status flag is set to 1. After all operations are completed, the interrupt flag is cleared, the interrupt is exited, and the main program returns to continue execution. If a bounce is detected within the anti-jitter timing window, it is determined to be interference jitter caused by electromagnetic interference or power supply ripple. No interrupt is triggered, and the original state detection continues.

[0025] Upon confirmation of a valid falling edge transition, a falling edge interrupt is triggered, and the current system timestamp is recorded as the refresh end time. Simultaneously, the refresh status flag is cleared. When the microcontroller initially detects a trend of the busy signal transitioning from high to low, a debounce timing window is initiated. Within this window, the busy signal level is continuously sampled. If the level remains consistently low without bounce, it is considered a valid falling edge transition, triggering a falling edge external interrupt and entering the interrupt response process. During the interrupt response, the interrupt status register is read to confirm a falling edge trigger, and the current system timer count is read, marked as the refresh end time, and stored. The refresh status flag is also cleared. After completion, the interrupt flag is cleared, the interrupt process exits, and the main program returns. If a level bounce is detected within the debounce window, it is considered interference jitter, and a falling edge interrupt is not triggered.

[0026] The continuous level state of the busy signal, the refresh start time, and the refresh end time together constitute the timing reference signal. The refresh status flag is used to identify the current working stage of the e-ink screen. The microcontroller maintains a timing data storage area in memory, recording the time and type of each valid transition in chronological order. Combined with the real-time level of the busy signal, a complete timing reference signal is formed for retrieval. The refresh status flag is a 1-bit Boolean variable, which can be read by various functional modules of the system. A bit value of 1 indicates that the current stage is dynamic refresh, and a bit value of 0 indicates that the current stage is steady-state maintenance. It is the core judgment basis for identifying the working stage and matching brightness parameters.

[0027] In one embodiment, the microcontroller parses the timing reference signal, reads the real-time level state of the busy signal, updates the bit value of the internal refresh status flag, and records the current system timestamp. The microcontroller's status parsing task runs periodically at a fixed frequency of 1kHz, performing a timing parsing operation every 1 millisecond. During each parsing, it first reads the current level value of the general-purpose input / output port to obtain the real-time level state of the busy signal, and then combines it with the refresh status flag bit value updated by the interrupt response process to complete the determination of the current working stage. The current system timestamp comes from the global system timer shared with the interrupt response process, ensuring that the time reference for stage determination is consistent with the time reference for signal acquisition, and there is no timing deviation. After each working stage determination is completed, the system timestamp of this determination is recorded synchronously as a time reference for brightness switching phase alignment.

[0028] If the refresh status flag has a bit value of 1, the e-ink screen is determined to be in a dynamic refresh phase. The microcontroller generates a first target backlight intensity parameter by matching a preset first mapping relationship. The first target backlight intensity parameter corresponds to a first brightness state. The first mapping relationship is a brightness parameter lookup table pre-stored in the microcontroller's non-volatile memory. The dynamic refresh phase corresponds to a unified first target backlight intensity parameter, which is stored in the form of a PWM drive control signal duty cycle value. The default setting is 80% duty cycle, corresponding to a light-emitting surface brightness of approximately 300 lux. This brightness level has been optically calibrated and can provide sufficient supplementary light intensity during the movement of ink particles, effectively improving the image contrast during the refresh process and reducing ghosting. The first mapping relationship allows users to adjust it in multiple levels through system settings, with an adjustment range of 50% to 100% duty cycle to adapt to display requirements under different ambient lighting conditions.

[0029] If the refresh status flag has a bit value of 0, the e-ink screen is determined to be in a steady-state maintenance phase. The microcontroller generates a second target backlight intensity parameter by matching a preset second mapping relationship. This second target backlight intensity parameter corresponds to a second brightness state. The second mapping relationship is also stored in non-volatile memory in the form of a lookup table. The steady-state maintenance phase corresponds to the second target backlight intensity parameter, which is set to a 30% duty cycle by default, corresponding to a light-emitting surface brightness of approximately 80 lux. This brightness level can reduce the continuous power consumption of the backlight system while ensuring clear readability of static images, fully meeting the usage characteristics of e-ink screens for long-term static display. The second mapping relationship also supports multi-level adjustment by the user, with an adjustment range of 0% to 50% duty cycle. Users can freely set the steady-state brightness according to their reading needs. In extreme power-saving scenarios, it can be set to 0%, which completely turns off the backlight and relies entirely on ambient light reflection for display.

[0030] In this process, the backlight intensity in the first brightness state is higher than that in the second brightness state. During the dynamic refresh phase, the backlight brightness is increased to compensate for the decrease in contrast caused by the movement of ink particles, ensuring the display clarity during the refresh process. During the steady-state maintenance phase, the backlight brightness is reduced to reduce ineffective power consumption and extend the device's battery life. The differentiated brightness settings in the two working phases fully match the optical characteristics of the bistable display of the e-ink screen, achieving synergistic optimization of display effect and system energy efficiency.

[0031] Reference Figure 4This diagram illustrates a dual-stage dimming brightness comparison for a backlighting method applied to e-ink screens. The horizontal axis represents time, and the vertical axis represents the relative value of backlight brightness. Traditional fixed brightness schemes use a globally uniform brightness level, continuously outputting the same brightness during the steady-state maintenance phase, resulting in significant wasted power consumption. This invention employs a dual-stage differentiated dimming strategy: maintaining high brightness output during the dynamic refresh phase to compensate for the contrast reduction caused by the movement of ink particles, ensuring display clarity during the refresh process; and reducing brightness output to a low level during the steady-state maintenance phase, ensuring only basic readability of static images. The brightness difference between the two phases represents the power consumption optimization space during the steady-state phase, significantly reducing the average operating power consumption of the backlight system and perfectly matching the long-term static display characteristics of e-ink screens.

[0032] In a preferred embodiment, the dynamic refresh phase can be further subdivided into three sub-modes: full refresh mode, partial refresh mode, and fast refresh mode. Different refresh modes correspond to different levels of the first target backlight intensity parameter. The microcontroller calculates the refresh duration by the difference between the rising edge timestamp and the falling edge timestamp, and compares it with a preset duration threshold to automatically identify the current refresh mode: a refresh duration greater than 200 milliseconds is determined to be full refresh mode, corresponding to the highest level of the first target backlight intensity parameter, with a default duty cycle of 90%; a refresh duration between 50 milliseconds and 200 milliseconds is determined to be partial refresh mode, corresponding to the middle level, with a default duty cycle of 70%; and a refresh duration less than 50 milliseconds is determined to be fast refresh mode, corresponding to the lowest level, with a default duty cycle of 50%.

[0033] In one embodiment, the microcontroller generates a PWM drive control signal matching the target brightness based on the corresponding value of the target backlight intensity parameter. The PWM drive control signal is a pulse width modulation signal generated by the microcontroller. The timer operates in up-clocking mode, with the clock source being a 72MHz clock obtained by dividing the system's main frequency. The timer's auto-reload value is set to 3599, corresponding to a PWM drive control signal frequency of 20kHz. The duty cycle of the PWM drive control signal is controlled by the timer's capture-compare register, with a comparison value range of 0~3600, corresponding to a duty cycle of 0%~100%, providing 3601 levels of brightness adjustment precision, enabling a smooth brightness transition imperceptible to the human eye. After reading the currently effective target backlight intensity parameter, the microcontroller calculates the brightness and duty cycle according to a preset formula:

[0034] Where Compare is the value to be written to the capture compare register, and ARR is the timer auto-reload value, which is 3599 in this embodiment. This represents the target brightness value corresponding to the current target backlight intensity parameter, in Iux. This is the maximum brightness value when the optical module outputs at full duty cycle, factory calibrated to 300 Iux. After calculating the comparison value, it is written to the capture comparison register, and the timer hardware automatically outputs a square wave signal with the corresponding duty cycle based on the comparison value; The working phase switching edges are extracted from the timing reference signal. These working phase switching edges include the rising edge at the start of the dynamic refresh phase and the falling edge at the start of the steady-state maintenance phase. A single high-level timer of the microcontroller is configured with an input capture channel. This input capture channel establishes an internal connection with the general-purpose input / output pin connected to the busy signal through the chip's internal I / O multiplexing matrix. Level changes on the pin can be directly sent to the timer's capture input. The input capture channel is configured in a dual-edge capture mode, where both rising and falling edges can trigger the capture action. An internal digital filtering unit is configured within the channel, with a filtering sampling frequency set to 1 / 8 of the timer's main frequency. A valid transition is determined only after eight consecutive samples show consistent levels, used to filter out extremely narrow nanosecond-level glitches, serving as the first level of hardware-level anti-jitter.

[0035] When the busy signal undergoes a level transition and passes through the first-stage hardware filtering, the input capture channel detects the rising edge transition trend. It first reports the level change event to the interrupt controller, triggering an external I / O interrupt. Within the interrupt service routine, a software debouncing timing window is initiated, continuously sampling the busy signal level at a frequency of 100kHz. After the 5-millisecond debouncing window ends and the level stabilizes at a high level, the software determines it as a valid rising edge transition. At this point, it reads the timer counter value automatically latched by the input capture channel at the moment of the transition and stores this timer counter value in the rising edge time variable in memory, marking it as the starting rising edge time of the dynamic refresh phase. The input capture latching action occurs at the hardware instant of the transition, resulting in a time difference with the software debouncing determination. However, the latched value is always the precise count value at the exact moment the transition occurs, and there is no time deviation due to the delay of software debouncing.

[0036] Similarly, when the busy signal has a falling edge transition, after hardware filtering, an external interrupt is triggered, software debouncing verification is started, and after confirming that the level is stable at a low level, the falling edge time count value automatically latched by the input capture channel is read and stored in the falling edge time variable in memory, which is marked as the starting falling edge time of the steady-state maintenance phase.

[0037] Reference Figure 3This image presents a phase alignment timing comparison diagram of a backlight method applied to e-ink screens. From top to bottom, it shows the busy signal waveform, the traditional dimming PWM waveform, and the dimming PWM waveform of this invention. The high-level range of the busy signal corresponds to the dynamic refresh phase of the e-ink screen, while the low-level range corresponds to the steady-state maintenance phase. The switching edge between these two phases serves as the true time reference for the display phase. Traditional independent dimming schemes, due to their lack of synchronization with the display timing, typically lag behind the display phase switching edge, resulting in significant timing deviations. This leads to insufficient brightness during the initial refresh phase and excessive brightness during the initial steady-state phase.

[0038] Using the switching edge of the aforementioned working phase as a clock reference, the brightness switching time of the PWM drive control signal is adjusted to align the rising edge of the brightness of the PWM drive control signal with the starting rising edge of the dynamic refresh phase, and the falling edge of the brightness with the starting falling edge of the steady-state maintenance phase, thus completing phase alignment. Phase alignment is achieved using a hardware timer comparison output mechanism: using the captured rising edge time as the time origin, the duty cycle update effective time of the PWM drive control signal timer is directly configured as the starting point of the next PWM drive control signal cycle, so that the rising edge of brightness coincides perfectly with the starting edge of screen refresh in time; similarly, the falling edge is configured with the captured falling edge time as a reference to ensure that the falling edge of brightness coincides perfectly with the ending edge of screen refresh.

[0039] The phase-aligned PWM drive control signal is output to the control input port of the backlight drive unit. The PWM drive control signal output from the microcontroller timer channel is connected to the dedicated PWM dimming signal input pin of the backlight drive chip as the brightness adjustment control input of the backlight drive chip; the dedicated PWM dimming input pin is a dedicated dimming signal receiving port built into the backlight drive chip, used to shape the input PWM drive control signal. The backlight driving unit converts the PWM drive control signal into power and outputs a drive current corresponding to the target backlight intensity to the optical module, driving the optical module to operate stably at the target brightness. The chip continuously collects the voltage across the sampling resistor and compares it with an internal reference voltage, using loop regulation to control the switching of the power transistor and maintain a constant output current. After the PWM dimming signal is connected to the chip's dimming pin, the chip's internal dimming logic controls the on / off time ratio of the output current according to the duty cycle of the PWM drive control signal: when the duty cycle is 100%, the output is fully on, the LED is continuously lit, and the output current is the full-scale current of 150mA set by the sampling resistor; when the duty cycle decreases, the output current switches on and off at the same proportional time, and the average brightness perceived by the human eye decreases linearly with the duty cycle.

[0040] In one embodiment, the actual emitted light brightness of the light module is collected by a photoelectric sensor on the backlight emitting side. The analog light sensor signal is converted into a digital signal by an analog-to-digital converter to generate the real-time brightness feedback signal. The actual brightness value corresponding to the real-time brightness feedback signal is then subtracted from the target backlight intensity parameter to obtain the current brightness deviation value. The microcontroller's calibration task runs periodically at a frequency of 1kHz, consistent with the sampling rate. Each time it executes, it reads the latest sampled actual brightness value from the brightness data buffer and subtracts it from the currently effective target backlight intensity parameter. The calculation formula is as follows:

[0041] in, The brightness deviation at the k-th sampling time is... This represents the target brightness value corresponding to the current target backlight intensity parameter. This represents the actual brightness value obtained from the k-th sample. A positive deviation value indicates that the actual brightness is lower than the target brightness, requiring an increase in backlight output; a negative deviation value indicates that the actual brightness is higher than the target brightness, requiring a decrease in backlight output; and a deviation value of zero indicates that the actual brightness matches the target brightness.

[0042] Based on the magnitude and direction of the current brightness deviation, a corresponding deviation correction amount is generated using a preset proportional-integral (PI) control algorithm. The PI control algorithm consists of a proportional term and an integral term, and its calculation formula is as follows:

[0043] in, Let k be the deviation correction amount. This is the proportionality coefficient. The integral coefficient is... The sampling period is set to 1 millisecond. The proportional term directly outputs the correction amount based on the magnitude of the current instantaneous deviation; the larger the deviation, the stronger the correction, used for rapid response to brightness changes. The integral term accumulates historical deviations to eliminate steady-state error, ensuring that the brightness ultimately converges accurately to the target value. Proportional coefficient. The default setting is 0.05, the integral coefficient. The default setting is 0.002. Both sets of parameters have been tuned by the system to balance response speed and stability, avoiding brightness overshoot and oscillation. To prevent excessive accumulation of the integral term from causing system overshoot, the algorithm has an integral limiting mechanism. The upper and lower limits of the integral accumulation value are limited to ±20% of the maximum duty cycle. Once the limiting is triggered, the integral accumulation stops, thus preventing integral saturation.

[0044] The effective duty cycle parameter of the drive control signal is corrected in reverse according to the deviation correction amount, and the control command output to the backlight drive unit is updated. The microcontroller adds the deviation correction amount output by the PI algorithm to the duty cycle comparison value of the current PWM drive control signal and updates the value of the comparison register: when the actual brightness is low and the deviation value is positive, the correction amount is positive, the duty cycle comparison value increases, the output duty cycle increases, and the backlight brightness increases; when the actual brightness is high and the deviation value is negative, the correction amount is negative, the duty cycle comparison value decreases, the output duty cycle decreases, and the backlight brightness decreases, thereby achieving reverse correction. The updated comparison value also takes effect at the beginning of the next PWM drive control signal cycle through the shadow register preloading mechanism to avoid output glitches caused by sudden changes in the duty cycle in the middle of the cycle and to ensure the integrity of the PWM drive control signal waveform. The updated PWM drive control signal is continuously output to the backlight drive unit, driving the light module to operate according to the corrected brightness.

[0045] The system iteratively executes brightness acquisition, deviation calculation, and signal correction steps to gradually converge and stabilize the actual output brightness of the backlight at the target backlight intensity. The correction system runs continuously in a 1-millisecond cycle, completing one sampling, calculation, and correction cycle in each cycle. After the target brightness is switched, the actual brightness gradually converges to near the target brightness value and remains stable within a deviation range of ±2%. (Refer to...) Figure 2 Here is a system structure block diagram of a backlight system applied to an e-ink screen according to an embodiment of the present invention, comprising: The signal acquisition unit is used to acquire the timing reference signal of the e-ink screen driving link and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side. The timing reference signal is used to identify the timing state of screen refresh, and the real-time brightness feedback signal is used to identify the actual effective brightness of the backlight illuminating the e-ink screen. The state analysis unit is used to analyze the timing reference signal, identify the current working stage of the e-ink screen, and generate the target backlight intensity parameter corresponding to the current working stage by matching a preset mapping relationship. The working stage includes a dynamic refresh stage and a steady-state maintenance stage. The synchronous driving unit is used to generate a driving control signal according to the target backlight intensity parameter, and with the timing reference signal as the synchronous clock reference, after keeping the switching edge of the driving control signal in phase aligned with the switching edge of the current working stage, output the driving control signal to the backlight driving unit to drive the light module to adjust to the target backlight intensity. The correction unit is used to calculate the brightness deviation based on the real-time brightness feedback signal and the target backlight intensity parameter, generate the deviation correction amount, and fine-tune the driving control signal in reverse to converge the actual backlight brightness to the target backlight intensity.

[0046] For the specific implementation of each module in the above system example, please refer to the above method embodiments, which will not be repeated here.

[0047] In summary, this invention acquires the timing reference signal of the e-ink screen driving link and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side; analyzes the timing reference signal to identify the current working stage of the e-ink screen, matches a preset mapping relationship to generate the target backlight intensity parameter for the corresponding stage, the working stage includes a dynamic refresh stage and a steady-state maintenance stage; generates a PWM drive control signal based on the target backlight intensity parameter, uses the timing reference signal as a synchronization clock reference, keeps the switching edge of the drive control signal in phase aligned with the switching edge of the current working stage, and outputs it to the backlight driving unit to drive the light module to adjust towards the target brightness; calculates the brightness deviation based on the real-time brightness feedback signal and the target backlight intensity parameter, generates a deviation correction amount through a proportional-integral control algorithm and fine-tunes the drive control signal in reverse, and converges the actual backlight brightness to the target backlight intensity, thereby achieving precise synchronization of brightness switching and screen refresh, dual-stage differentiated energy efficiency optimization, brightness consistency throughout the entire life cycle, and low-cost deployment of general-purpose hardware.

[0048] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A backlighting method for use with e-ink screens, characterized in that, Includes the following steps: The timing reference signal of the e-ink screen and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side are collected; wherein, the timing reference signal is used to identify the timing state of screen refresh, and the real-time brightness feedback signal is used to identify the actual effective brightness of the backlight illuminating the e-ink screen. The timing reference signal is analyzed to identify the current working stage of the e-ink screen, and the target backlight intensity parameter corresponding to the current working stage is generated by matching a preset mapping relationship. The working stage includes a dynamic refresh stage and a steady-state maintenance stage. A drive control signal is generated based on the target backlight intensity parameter. The timing reference signal is used as the synchronization clock reference. After the switching edge of the drive control signal is phase-aligned with the switching edge of the current working stage, the drive control signal is output to the backlight drive unit to drive the light module to adjust to the target backlight intensity. The brightness deviation is calculated based on the real-time brightness feedback signal and the target backlight intensity parameter, a deviation correction amount is generated, and the driving control signal is finely adjusted in reverse to converge the actual backlight brightness to the target backlight intensity.

2. The backlighting method for an e-ink screen according to claim 1, characterized in that, Acquiring the timing reference signal of the e-ink screen driving link includes the following steps: Connect the busy signal pin of the e-ink screen driver chip to the general-purpose input / output pin of the microcontroller, configure the general-purpose input / output pin to input mode, and enable the dual-edge external interrupt, which includes a rising edge and a falling edge. The microcontroller sends screen refresh commands to the e-ink screen driver chip via the communication bus and detects the level changes of the busy signal in real time. When the busy signal is detected to transition from low to high, a rising edge interrupt is triggered, and the current system timestamp is recorded as the refresh start time. Simultaneously, the refresh status flag is set to 1 bit. When the busy signal is detected to change from high to low, a falling edge interrupt is triggered and the current system timestamp is recorded as the refresh end time. At the same time, the bit value of the refresh status flag is cleared to zero. The continuous level state of the busy signal, the refresh start time, and the refresh end time together constitute the timing reference signal, and the refresh status flag is used to identify the current working stage of the e-ink screen.

3. The backlighting method for an e-ink screen according to claim 2, characterized in that, The process of analyzing the timing reference signal, identifying the current operating stage of the e-ink screen, and generating the target backlight intensity parameters corresponding to the current operating stage by matching includes the following steps: The microcontroller parses the timing reference signal, updates the bit value of the internal refresh status flag, and records the current system timestamp. When the refresh status flag has a bit value of 1, it is determined that the current state is in the dynamic refresh stage. The microcontroller generates a first target backlight intensity parameter by matching a preset first mapping relationship. The first target backlight intensity parameter corresponds to a first brightness state. When the refresh status flag has a bit value of 0, it is determined that the current state is in a steady state maintenance phase. The microcontroller generates a second target backlight intensity parameter by matching a preset second mapping relationship. The second target backlight intensity parameter corresponds to a second brightness state. The backlight intensity in the first brightness state is higher than the backlight intensity in the second brightness state.

4. The backlighting method for an e-ink screen according to claim 3, characterized in that, A drive control signal is generated based on the target backlight intensity parameter. Using the timing reference signal as a synchronization clock reference, the switching edge of the drive control signal is phase-aligned with the switching edge of the current working stage, and then the drive control signal is output to the backlight driving unit to drive the light module to adjust towards the target backlight intensity. This includes the following steps: The microcontroller generates a PWM drive control signal that matches the target brightness based on the corresponding value of the target backlight intensity parameter. Extract the two working phase switching edges from the timing reference signal, including the rising edge at the start of the dynamic refresh phase and the falling edge at the steady state maintenance phase; Based on the working phase switching edge as the clock reference and the clock reference as the synchronous trigger point, the brightness switching time of the PWM drive control signal is adjusted so that the brightness rising edge of the PWM drive control signal is aligned with the starting rising edge of the dynamic refresh phase and the brightness falling edge is aligned with the starting falling edge of the steady-state maintenance phase, thus completing phase alignment. The PWM drive control signal that has completed phase alignment is output to the control input port of the backlight drive unit; The backlight driving unit converts the PWM driving control signal into power and outputs a driving current corresponding to the target backlight intensity to the optical module, thereby driving the optical module to operate stably at the target brightness state.

5. The backlighting method for an e-ink screen according to claim 1, characterized in that, The brightness deviation is calculated based on the real-time brightness feedback signal and the target backlight intensity parameter. A deviation correction amount is generated and the driving control signal is finely adjusted in reverse to converge the actual backlight brightness to the target backlight intensity. The process includes the following steps: The actual output brightness of the light module is collected by the photoelectric sensor on the backlight output side, and the analog light sensing signal is converted into a digital signal by the analog-to-digital conversion unit to generate a real-time brightness feedback signal. The difference between the actual brightness value corresponding to the real-time brightness feedback signal and the target backlight intensity parameter is calculated to obtain the deviation value of the current brightness. Based on the magnitude and direction of the current brightness deviation value, a corresponding deviation correction amount is generated using a preset proportional-integral algorithm; The effective duty cycle parameter of the drive control signal is corrected in reverse according to the deviation correction amount, and the control command output to the backlight drive unit is updated. The brightness acquisition, deviation calculation and signal correction are executed in a loop so that the actual output brightness of the backlight gradually converges and stabilizes at the target backlight intensity.

6. The backlighting method for an e-ink screen according to claim 3, characterized in that, The dynamic refresh phase includes full refresh mode, local refresh mode and fast refresh mode; Different refresh modes correspond to different primary target backlight intensity parameters. The primary target backlight intensity parameter is the highest for full refresh mode, followed by partial refresh mode, and the primary target backlight intensity parameter is the lowest for fast refresh mode.

7. A backlighting method for an e-ink screen according to claim 2, characterized in that, Before triggering an external interrupt, a double-edge debouncing check is performed, which includes: When a level change in the busy signal is detected, a pre-set anti-shake timing window is activated; Based on the continuous sampling of the busy signal level within the anti-shake timing window, if the level is stable, it is determined to be a valid transition, triggering the corresponding interrupt and recording the timestamp; If the voltage level bounces back, it is determined to be interference jitter and no interrupt is triggered.

8. A backlight system for use in e-ink displays, characterized in that, include: The signal acquisition unit is used to acquire the timing reference signal of the e-ink screen driving link and the real-time brightness feedback signal of the photoelectric sensor on the backlight output side. The timing reference signal is used to identify the timing state of screen refresh, and the real-time brightness feedback signal is used to identify the actual effective brightness of the backlight illuminating the e-ink screen. The state analysis unit is used to analyze the timing reference signal, identify the current working stage of the e-ink screen, and generate the target backlight intensity parameter corresponding to the current working stage by matching a preset mapping relationship. The working stage includes a dynamic refresh stage and a steady-state maintenance stage. The synchronous driving unit is used to generate a driving control signal according to the target backlight intensity parameter, and with the timing reference signal as the synchronous clock reference, after keeping the switching edge of the driving control signal in phase aligned with the switching edge of the current working stage, output the driving control signal to the backlight driving unit to drive the light module to adjust to the target backlight intensity. The correction unit is used to calculate the brightness deviation based on the real-time brightness feedback signal and the target backlight intensity parameter, generate the deviation correction amount, and fine-tune the driving control signal in reverse to converge the actual backlight brightness to the target backlight intensity.

9. A backlight device for use with e-ink screens, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method steps of any one of claims 1 to 7 for use with an e-ink screen.

10. A backlight storage medium for use in e-ink displays, wherein a computer program is stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method steps for applying an e-ink screen as described in any one of claims 1 to 7.

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