Static picture zero power consumption control method of color electronic paper label

Abstract

The invention discloses a static picture zero power consumption control method for a color electronic paper label, and relates to the field of electronic display driving. According to the method, a particle migration compensation model based on temperature sensing is constructed aiming at the problems that color electronic paper is easily interfered by the environment and static electric leakage exists in a peripheral circuit, and color deviation and contrast drift caused by environment change are effectively corrected by dynamically calculating the driving pulse duration and combining a color space jitter algorithm. In the aspect of energy consumption management, the system accurately recognizes the refreshing requirement by using an image hash comparison and local updating strategy, and executes power supply physical cut-off and IO port high-impedance isolation operation after picture updating is completed, so that the static power consumption of a hardware system is thoroughly eliminated; and in cooperation with a direct-current balance verification and timing anti-diffusion maintenance mechanism, charge accumulation and image blurring are effectively prevented, and dual optimization of image quality display and equipment endurance is realized.

Description

Technical Field

[0001] This invention relates to the field of electronic display driving, and in particular to a method for zero-power control of still images in color electronic paper signs. Background Technology

[0002] Electronic paper display technology, due to its paper-like texture and bistable characteristics, is widely used in electronic shelf labels, advertising signs, and other fields. However, existing color electronic paper driving solutions still have power consumption bottlenecks and display quality issues: On the one hand, although the screen itself theoretically does not consume power when the image is static, the peripheral control circuits, such as MCUs, charge pumps, and timing controllers, will still generate significant static leakage current if not completely disconnected or isolated, severely shortening battery life; on the other hand, color electronic paper uses particles with different charges and mobility, such as cyan, magenta, yellow, and white, for color mixing, and its color presentation is highly susceptible to the influence of ambient temperature and light. Traditional fixed waveform driving often leads to slow particle movement at low temperatures, causing color cast, or a decrease in contrast due to the photovoltaic effect under strong light; in addition, the lack of DC balance verification and maintenance mechanisms for long-term static display can easily lead to the accumulation of residual charge on the screen and particle diffusion blurring, affecting the screen's lifespan and image quality. Summary of the Invention

[0003] To address the aforementioned problems in the existing technology, the present invention aims to provide a method for zero-power control of still images in color electronic paper signs, the method comprising the following steps: Step S1: In the system wake-up state, acquire the color image data to be displayed, and parse the color image data to obtain the red, green and blue color components of the pixel array.

[0004] Step S2: Based on the physical characteristics of the current microcapsule electrophoretic display panel, the red, green and blue color components are mapped to the corresponding multicolor particle driving voltage index values ​​to generate target frame buffer data.

[0005] Step S3: Collect the current ambient temperature data, calculate the duration of the driving pulse for each pixel using the particle migration compensation model, and generate a driving waveform sequence.

[0006] Step S4: Send the driving waveform sequence to the source driver and gate driver of the microcapsule electrophoretic display panel to drive the colored electrophoretic particles to migrate to a predetermined position to present a still image.

[0007] Step S5: After detecting that the drive waveform sequence has been sent and the busy signal from the microcapsule electrophoresis display panel has been cleared, perform hardware isolation and power cut-off operations before deep sleep and enter zero power consumption mode.

[0008] Furthermore, step S5 includes the following sub-steps: Step S501: A soft shutdown command is sent to the timing controller of the microcapsule electrophoresis display panel through the serial peripheral interface to stop the operation of the charge pump circuit.

[0009] Step S502: Modify the mode configuration register of all general-purpose input / output pins connected to the microcontroller and the microcapsule electrophoresis display panel to high-impedance input mode or analog input mode.

[0010] Step S503: Send a control signal to the board-level power management chip to disconnect the physical connection between the analog power supply voltage and the digital logic power supply voltage of the microcapsule electrophoresis display panel.

[0011] Step S504: Switch the microcontroller to the stop mode, keeping only the real-time clock module and the external interrupt wake-up module in operation.

[0012] Furthermore, the duration of the driving pulse is used to compensate for the effect of temperature on the viscosity coefficient of electrophoretic particles, and its calculation formula is as follows: in, Indicates the duration of the driving pulse; Indicates the reference drive duration at the standard reference temperature; The viscosity activation energy constant of the electrophoretic solution; Represents the Boltzmann constant; This represents the current absolute ambient temperature. Indicates the standard reference absolute temperature; This represents the color gradation distance between the target color index of the current pixel and the color index of the previous frame; This represents the color level switching delay coefficient; the calculation formula corrects for the particle mobility change caused by temperature through an exponential term, and adds the additional time compensation required for color level switching.

[0013] Furthermore, step S2 performs color space dithering: converting the red, green, and blue color components into a four-color particle concentration space of cyan, magenta, yellow, and white; calculating the quantization error between the converted pixel color and the closest color in the standard seven-color palette; and using the Floyd-Steinberg error diffusion algorithm, distributing the quantization error to adjacent unprocessed pixels according to a preset ratio, and updating the particle concentration values ​​of adjacent pixels.

[0014] Furthermore, before step S1, a wake-up trigger determination step is included: the microcontroller receives the new image feature code transmitted by the wireless communication module in low-power listening mode; reads the old image feature code of the currently displayed screen from the non-volatile memory; calculates the hash distance between the new image feature code and the old image feature code; and triggers a system reset signal and executes step S1 only when the hash distance is not zero, otherwise the zero-power hold mode is maintained.

[0015] Furthermore, in step S3, when generating the driving waveform sequence, a DC balance check is performed: the integral area of ​​all positive voltage pulses and the integral area of ​​negative voltage pulses in the driving waveform sequence are counted; the difference between the two is calculated as the residual DC component; if the absolute value of the residual DC component exceeds a preset safety threshold, a balance pulse segment with opposite polarity and equal area is inserted at the end of the driving waveform sequence to eliminate the accumulated charge in the electrophoretic fluid.

[0016] Furthermore, step S4 executes a phased driving logic: in the first phase, an inverse complement waveform is loaded to drive the electrophoretic particles of all pixels to a consistent reset state of pure black or pure white; in the second phase, a color synthesis waveform is loaded, and by controlling voltage pulses of different amplitudes and widths, the cyan, magenta, and yellow particles are separated into layers to the visible side by utilizing the differences in charge and movement speed of the electrophoretic particles.

[0017] Furthermore, step S5 is followed by a periodic refresh and maintenance step: Read the last refresh timestamp recorded by the real-time clock module; calculate the time difference between the current time and the last refresh timestamp; if the time difference exceeds the preset screen hold limit period, force the system to wake up; after performing the full-screen white-black-white clearing driver operation, reload the current static screen data to prevent the image from blurring due to long-term Brownian motion of electrophoretic particles.

[0018] Furthermore, in step S1, when acquiring the color image data to be displayed, local update recognition is performed: the color image data is compared with the current frame buffer data row by row pixel by pixel; the minimum row index and maximum row index, as well as the minimum column index and maximum column index of the pixels that have changed color are recorded; a minimum rectangular update region is constructed based on the recorded index values; in step S4, the driving waveform sequence is sent only to the pixels within the minimum rectangular update region, while the pixels outside the region maintain their original voltage state.

[0019] Furthermore, step S2 also includes a common electrode voltage adjustment step: acquiring ambient light intensity data from a light sensor; querying a pre-stored common electrode voltage lookup table based on the light intensity data to obtain the optimal common electrode reference voltage value; and adjusting the DC voltage output to the common terminal of the microcapsule electrophoresis display panel via a digital-to-analog converter to correct the display contrast drift caused by the photovoltaic effect. Compared with existing technologies, the beneficial effects of this invention are as follows: This invention constructs an adaptive driving model based on environmental perception. By collecting real-time temperature and illumination data, it accurately calculates the driving pulse duration using an exponential formula that includes the Boltzmann constant and viscous activation energy, and dynamically adjusts the common electrode voltage. This effectively compensates for the influence of temperature on particle mobility and the photovoltaic effect caused by illumination, ensuring the accuracy of color reproduction under different environments. Combined with color space dithering processing based on error diffusion, it significantly improves the visual display effect under a limited color gamut.

[0020] This invention proposes an ultimate zero-power management and maintenance strategy. After the screen refresh is complete, not only is the timing controller turned off by software instructions, but the power connection is also physically disconnected and all I / O ports are configured to a high-impedance state, completely eliminating static power consumption. The system has a built-in wake-up triggering mechanism based on hash comparison and timed maintenance logic. The refresh is only started when the image content actually changes, and a full-screen clearing operation is performed periodically to prevent image blurring caused by Brownian motion of particles. Thus, while ensuring ultra-long battery life, the lifespan of the electronic paper sign is effectively extended. Attached Figure Description

[0021] Figure 1 This is an exemplary flowchart of the power consumption control method of the present invention.

[0022] Figure 2 This is an exemplary flowchart of the signal transmission steps of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments.

[0024] like Figure 1 As shown, this invention provides a method for zero-power control of still images on color electronic paper signs. The method includes the following steps: Step S1: In the system wake-up state, acquire the color image data to be displayed and parse the color image data to obtain the red, green, and blue color components of the pixel array. The system wake-up state is usually triggered by a timer interrupt or a wireless radio frequency wake-up signal. The color image data to be displayed can be in BMP, JPEG, or PNG format and is sent to the local buffer via a wireless network.

[0025] Before step S1, a wake-up trigger determination step is included: the microcontroller receives the new image feature code transmitted by the wireless communication module in low-power listening mode; reads the old image feature code of the currently displayed screen from non-volatile memory; calculates the hash distance between the new image feature code and the old image feature code; and triggers a system reset signal and executes step S1 only if the hash distance is not zero; otherwise, it continues to maintain the zero-power hold mode. The feature code can be a CRC32 or MD5 checksum. A non-zero hash distance means that the screen content has undergone a substantial change, avoiding invalid refreshes.

[0026] In step S1, when acquiring the color image data to be displayed, local update recognition is performed: the color image data is compared with the current frame buffer data row by row; the minimum row index and maximum row index, as well as the minimum column index and maximum column index of the pixels that have changed color are recorded; a minimum rectangular update region is constructed based on the recorded index values; in step S4, the driving waveform sequence is sent only to the pixels within the minimum rectangular update region, while the pixels outside the region maintain their original voltage state.

[0027] Step S2: Based on the physical characteristics of the current microcapsule electrophoretic display panel, the red, green, and blue color components are mapped to the corresponding multicolor particle driving voltage index values ​​to generate target frame buffer data. Microcapsule electrophoretic display panels typically contain millions of microcapsules, each containing positively or negatively charged colored pigment particles.

[0028] Step S2 performs color space dithering: converts the red, green and blue color components into a four-color particle density space of cyan, magenta, yellow and white; calculates the quantization error between the converted pixel color and the closest color in the standard seven-color palette; and uses the Floyd-Steinberg error diffusion algorithm to distribute the quantization error to adjacent unprocessed pixels according to a preset ratio, and updates the particle density values ​​of adjacent pixels.

[0029] In this embodiment, step S2 further includes a common electrode voltage adjustment step: acquiring ambient light intensity data from a light sensor; querying a pre-stored common electrode voltage lookup table based on the light intensity data to obtain the optimal common electrode reference voltage value; and adjusting the DC voltage output to the common terminal of the microcapsule electrophoresis display panel via a digital-to-analog converter to correct the display contrast drift caused by the photovoltaic effect.

[0030] Step S3: Collect the current ambient temperature data, calculate the duration of the driving pulse for each pixel using the particle migration compensation model, and generate a driving waveform sequence.

[0031] The duration of the driving pulse is used to compensate for the effect of temperature on the viscosity coefficient of electrophoretic particles, and its calculation formula is as follows: in, Indicates the duration of the driving pulse; Indicates the reference drive duration at the standard reference temperature; The viscosity activation energy constant of the electrophoretic solution; Represents the Boltzmann constant; This represents the current absolute ambient temperature. Indicates the standard reference absolute temperature; This represents the color gradation distance between the target color index of the current pixel and the color index of the previous frame; This represents the color level switching delay coefficient; the calculation formula corrects for the particle mobility change caused by temperature through an exponential term, and adds the extra time compensation required for color level switching.

[0032] The first term of the formula Actually, it's calculating a "temperature correction factor." When the ambient temperature... Below reference temperature When the exponential term is positive, the calculated correction factor is greater than 1, leading to a change in driving time. The time required is significantly extended. This aligns with the physical fact that at low temperatures, the electrophoretic solution thickens, increasing drag and requiring particles to migrate to the screen surface more quickly. Conversely, at high temperatures, the correction factor is less than 1, shortening the driving time and preventing overshoot or ghosting caused by excessively fast particle movement.

[0033] Formula 2 Compensation for "state history" and "color distance" is introduced. Different colored particles have different volumes, charges, and surface potentials, and therefore their electrophoretic mobilities vary. For example, large red particles with low charges migrate much slower than small black particles with high charges. The "energy distance" required to switch from the current color state to the target color state is quantified. Through linear compensation terms, it is ensured that even hard-to-drive color particles can obtain sufficient pulse energy, thereby achieving accurate color reproduction.

[0034] In step S3, when generating the driving waveform sequence, a DC balance check is performed: the integral area of ​​all positive voltage pulses and the integral area of ​​negative voltage pulses in the driving waveform sequence are counted; the difference between the two is calculated as the residual DC component; if the absolute value of the residual DC component exceeds the preset safety threshold, a balance pulse segment with opposite polarity and equal area is inserted at the end of the driving waveform sequence to eliminate the accumulated charge in the electrophoretic fluid.

[0035] Step S4: Send a driving waveform sequence to the source driver and gate driver of the microcapsule electrophoresis display panel to drive the colored electrophoretic particles to migrate to a predetermined position to present a still image.

[0036] In specific implementation, step S4 executes a phased driving logic: The first phase loads an inverse complement waveform to drive all pixel electrophoretic particles to a consistent reset state of pure black or pure white; the second phase loads a color synthesis waveform, controlling voltage pulses of different amplitudes and widths to separate cyan, magenta, and yellow particles into layers on the visible display side, utilizing the differences in charge and movement speed of the electrophoretic particles. The inverse complement waveform eliminates residual images from the previous frame. The color synthesis stage utilizes the different electrophoretic mobility of different color particles to achieve layered display.

[0037] Step S4 executes the phased driving logic: In the first phase, the inverse complement waveform is loaded to drive the electrophoretic particles of all pixels to a consistent reset state of pure black or pure white; in the second phase, the color synthesis waveform is loaded, and by controlling voltage pulses of different amplitudes and widths, the cyan, magenta, and yellow particles are separated into layers to the visible side of the display by utilizing the differences in charge and movement speed of the electrophoretic particles.

[0038] Step S5: After detecting that the drive waveform sequence has been sent and the busy signal from the microcapsule electrophoresis display panel has been cleared, perform hardware isolation and power cut-off operations before deep sleep and enter zero power consumption hold mode.

[0039] like Figure 2 As shown, step S5 in this embodiment includes the following sub-steps: In step S501, a soft shutdown command is sent to the timing controller of the microcapsule electrophoresis display panel through the serial peripheral interface to stop the operation of the charge pump circuit. The soft shutdown command usually writes a specific value to the register to gracefully shut down the internal boost circuit and prevent voltage surges from damaging the screen.

[0040] Step S502: Modify the mode configuration register of all general-purpose input / output pins connecting the microcontroller to the microcapsule electrophoresis display panel to high-impedance input mode or analog input mode; setting the pins to high-impedance or analog input mode is the key to preventing leakage current and avoiding microamp-level leakage current generated through the pull-up resistors inside the screen.

[0041] Step S503: Send a control signal to the board-level power management chip to disconnect the physical connection switch between the analog power supply voltage and the digital logic power supply voltage of the microcapsule electrophoresis display panel; the physical connection switch is usually implemented using a PMOS transistor or load switch with low on-resistance to ensure that the power supply terminal of the screen is completely disconnected.

[0042] Step S504: Switch the microcontroller to stop mode, keeping only the real-time clock module and the external interrupt wake-up module active. In stop mode, the MCU's main clock is turned off, and current consumption can be reduced to below 1uA.

[0043] Step S5 is followed by a scheduled refresh and maintenance step: Read the last refresh timestamp recorded by the real-time clock module; calculate the time difference between the current time and the last refresh timestamp; if the time difference exceeds the preset screen hold limit period, force the system to wake up; after performing the full-screen white-to-white clear driver operation, reload the current static screen data to prevent the image from blurring due to long-term Brownian motion of electrophoretic particles.

[0044] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for zero-power control of still images in color electronic paper signs, characterized in that, The method includes the following steps: Step S1: In the system wake-up state, acquire the color image data to be displayed, and parse the color image data to obtain the red, green and blue color components of the pixel array; Step S2: Based on the physical characteristics of the current microcapsule electrophoresis display panel, map the red, green and blue color components to the corresponding multicolor particle driving voltage index values ​​to generate target frame buffer data; Step S3: Collect the current ambient temperature data, calculate the duration of the driving pulse for each pixel using the particle migration compensation model, and generate a driving waveform sequence. Step S4: Send the driving waveform sequence to the source driver and gate driver of the microcapsule electrophoretic display panel to drive the colored electrophoretic particles to migrate to a predetermined position to present a still image; Step S5: After detecting that the drive waveform sequence has been sent and the busy signal from the microcapsule electrophoresis display panel has been cleared, perform hardware isolation and power cut-off operations before deep sleep and enter zero power consumption hold mode.

2. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, Step S5 includes the following sub-steps: Step S501: Send a soft shutdown command to the timing controller of the microcapsule electrophoresis display panel through the serial peripheral interface to stop the operation of the charge pump circuit. Step S502: Modify the mode configuration register of all general-purpose input / output pins connected to the microcontroller and the microcapsule electrophoresis display panel to high-impedance input mode or analog input mode; Step S503: Send a control signal to the board-level power management chip to disconnect the physical connection between the analog power supply voltage and the digital logic power supply voltage of the microcapsule electrophoresis display panel. Step S504: Switch the microcontroller to the stop mode, keeping only the real-time clock module and the external interrupt wake-up module in operation.

3. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, The duration of the driving pulse is used to compensate for the effect of temperature on the viscosity coefficient of electrophoretic particles, and its calculation formula is as follows: in, Indicates the duration of the driving pulse; Indicates the reference drive duration at the standard reference temperature; The viscosity activation energy constant of the electrophoretic solution; Represents the Boltzmann constant; This represents the current absolute ambient temperature. Indicates the standard reference absolute temperature; This represents the color gradation distance between the target color index of the current pixel and the color index of the previous frame; This represents the color level switching delay coefficient; the calculation formula corrects for the particle mobility change caused by temperature through an exponential term, and adds the additional time compensation required for color level switching.

4. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, Step S2 performs color space dithering: the red, green and blue color components are converted into a four-color particle concentration space of cyan, magenta, yellow and white; the quantization error between the converted pixel color and the closest color in the standard seven-color palette is calculated; using the Floyd-Steinberg error diffusion algorithm, the quantization error is distributed to adjacent unprocessed pixels according to a preset ratio coefficient, and the particle concentration values ​​of adjacent pixels are updated.

5. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, Before step S1, a wake-up trigger determination step is also included: the microcontroller receives the new image feature code transmitted by the wireless communication module in low-power listening mode; reads the old image feature code of the currently displayed screen from the non-volatile memory; calculates the hash distance between the new image feature code and the old image feature code; and triggers a system reset signal and executes step S1 only when the hash distance is not zero, otherwise the zero-power hold mode is maintained.

6. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, In step S3, when generating the driving waveform sequence, a DC balance check is performed: the integral area of ​​all positive voltage pulses and the integral area of ​​all negative voltage pulses in the driving waveform sequence are calculated. The difference between the two is calculated as the residual DC component; if the absolute value of the residual DC component exceeds a preset safety threshold, a balancing pulse segment with opposite polarity and equal area is inserted at the end of the driving waveform sequence to eliminate the accumulated charge in the electrophoretic fluid.

7. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, Step S4 executes a phased driving logic: the first phase loads the inverse complement waveform to drive the electrophoretic particles of all pixels to a consistent reset state of pure black or pure white; the second phase loads the color synthesis waveform and, by controlling voltage pulses of different amplitudes and widths, uses the differences in charge and movement speed of the electrophoretic particles to separate cyan, magenta, and yellow particles into layers to the visible side of the display.

8. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, Step S5 is followed by a periodic refresh and maintenance step: Read the last refresh timestamp recorded by the real-time clock module; calculate the time difference between the current time and the last refresh timestamp; if the time difference exceeds the preset screen hold limit period, force the system to wake up; after performing the full-screen white-black-white clearing driver operation, reload the current static screen data to prevent the image from blurring due to long-term Brownian motion of electrophoretic particles.

9. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, In step S1, when acquiring the color image data to be displayed, local update recognition is performed: the color image data is compared with the current frame cache data row by row; the minimum row index and maximum row index, as well as the minimum column index and maximum column index of the pixels that have changed color are recorded; and the minimum rectangular update region is constructed based on the recorded index values. In step S4, the driving waveform sequence is sent only to pixels within the minimum rectangular update area, while pixels outside the area maintain their original voltage state.

10. The method for zero-power control of still images in a color electronic paper sign according to claim 1, characterized in that, Step S2 further includes a common electrode voltage adjustment step: acquiring ambient light intensity data from a light sensor; querying a pre-stored common electrode voltage lookup table based on the light intensity data to obtain the optimal common electrode reference voltage value; and adjusting the DC voltage output to the common terminal of the microcapsule electrophoresis display panel via a digital-to-analog converter to correct the display contrast drift caused by the photovoltaic effect.

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