Low-flicker adaptive backlight control device and method

Abstract

The invention discloses a low-flicker adaptive backlight control device and method, and relates to the technical field of backlight control of display equipment. The device comprises a multi-source sensing cooperation module, a main control processing unit, a dynamic threshold dual-dimming driving unit, a backlight module and a storage unit which are electrically connected in sequence, multi-dimensional parameters such as ambient light, screen content brightness and user eye states are synchronously collected through a multi-source sensing cooperation module; the main control processing unit calculates target brightness based on a scenarized weighted fusion model and a machine learning algorithm, and ensures output stability through PID dynamic compensation; the dynamic threshold dual-dimming driving unit dynamically adjusts the switching threshold of PWM dimming and similar DC dimming according to the change rate of ambient light and the fatigue state of a user, so that smooth flicker-free brightness transition is realized; the problems of low-brightness stroboflash, brightness jump, poor scene adaptability, dimming lagging and the like in the prior art are effectively solved, and flicker-free, smooth and personalized automatic backlight control is realized.

Description

Technical Field

[0001] This invention relates to the field of display device backlight control technology, specifically to a backlight control device and method that can achieve low flicker and adapt to multiple scenarios, applicable to various mobile terminals with display functions such as mobile phones, tablets, and vehicle displays, and especially suitable for low-brightness, high-frequency usage scenarios such as nighttime and reading. Background Technology

[0002] With the development of display technology, mobile terminal devices such as mobile phones, tablets, and automotive displays have been widely used in various scenarios. Backlight control is one of the key technologies affecting display effect and user experience. Currently, the mainstream backlight dimming technologies include analog dimming (DC dimming) and pulse width modulation dimming (PWM dimming). DC dimming changes brightness by adjusting the current, but it is prone to color shift and uneven brightness at low brightness. PWM dimming controls average brightness by rapidly switching LEDs on and off, but it is prone to flicker that is perceptible to the human eye at low brightness and low frequency, which may cause visual fatigue with long-term use.

[0003] To overcome the shortcomings of single dimming technology, existing technologies have proposed two hybrid dimming schemes: one is a high PWM duty cycle priority hybrid dimming technology, which integrates PWM and DC dimming in the low brightness range, with high duty cycle PWM as the core, in an attempt to achieve a low brightness without missing code effect; the other is a dual hybrid dimming technology, which integrates DC and PWM dimming at the same time, aiming to make up for the shortcomings of low brightness color shift of single DC dimming and flicker of single PWM dimming, and balance brightness uniformity and eye protection needs.

[0004] For example, through the patent document CN112885272A, which discloses a backlight adjustment method based on ambient light sensing and image content, it can be seen that the existing technology still has the following four shortcomings: 1) Flickering issue: Fixed-frequency PWM dimming is often used in low brightness ranges, and visible screen flicker is likely to occur when the frequency is below 120Hz; 2) Brightness jump: The backlight drive current adjustment step is too large, resulting in an uneven brightness transition in the low brightness range, which aggravates the perceived flicker. 3) Poor scene adaptability: The adjustment logic usually relies on a single ambient light parameter and fails to effectively combine the characteristics of the screen content with the user's real-time eye state, thus failing to meet the differentiated needs of multiple scenarios such as reading, gaming, and nighttime. 4) Dimming stutter: Some hybrid dimming technologies use a fixed mode switching threshold. When the ambient light changes suddenly or the user's status changes, dimming mode switching stutter and instantaneous flicker are likely to occur.

[0005] Therefore, there is an urgent need for a backlight control solution that can achieve flicker-free operation, smooth transition, and adaptability to various scenarios and user states. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-flicker adaptive backlight control device and method. Through the integrated design of multi-source parameter linkage, dynamic threshold dimming, and high-precision PID compensation, flicker-free, smooth, and personalized automatic backlight control is achieved, while optimizing device power consumption.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a low-flicker adaptive backlight control device, comprising: The multi-source sensing collaboration module, main control processing unit, dynamic threshold dual dimming drive unit, backlight module and storage unit are electrically connected in sequence, and the storage unit communicates bidirectionally with the main control processing unit. The multi-source sensing collaboration module integrates an ambient light sensor, a screen content brightness acquisition unit, and a human eye state detection unit to achieve multi-dimensional data synchronous acquisition of ambient light intensity, screen image brightness, and user eye state. The main control processing unit is a microprocessor with high-speed analog-to-digital conversion function, and has built-in multi-parameter linkage mapping algorithm, PID dynamic compensation module and machine learning module. The multi-parameter linkage mapping algorithm adopts a scenario-based weighted fusion model, which assigns weights to different parameters and can adaptively adjust them. The PID dynamic compensation module monitors the changes in drive current in real time and outputs correction commands. The machine learning module trains and updates algorithm parameters based on data manually adjusted by the user. The dynamic threshold dual dimming drive unit includes a PWM dimming module and a DC-like dimming module. Its core feature is that the dimming switching threshold can be dynamically adjusted according to the rate of change of ambient light and the degree of eye fatigue of the user, rather than a fixed value. PWM dimming is used in the high brightness range, and the low brightness range is switched to a DC-like linear dimming mode. High-precision current regulation is used to eliminate current surges. The backlight module uses a side-lit LED array; The storage unit is used to store various parameters and user data.

[0008] Secondly, the present invention also provides a low-flicker adaptive backlight control method based on the above-mentioned device, comprising the following steps: S1: Simultaneously acquire multi-source sensor data; S2: Calculate the target brightness value and introduce a comfortable brightness offset; S3: Dynamically adjust the dimming switching threshold and determine the target brightness range; S4: Activate the corresponding dimming mode and adjust the brightness at a smooth rate; S5: Stabilizes current in real time through PID compensation; S6: Machine learning optimization based on user-manual adjustments.

[0009] Compared with the prior art, the present invention has the following significant advantages: 1. Multi-source sensing and precise adaptation: By integrating three types of parameters—ambient light, screen content, and user status—it breaks through the limitations of traditional single ambient light sensing, making backlight adjustment more in line with actual usage scenarios and user physiological states, achieving true personalized adaptation.

[0010] 2. Dynamic threshold, smooth and seamless: It innovatively proposes a dynamic adjustment dimming mode switching threshold mechanism, which intelligently switches dimming modes according to sudden changes in the environment and user fatigue state, effectively avoiding the switching stuttering and flickering problems caused by fixed thresholds, and ensuring the ultimate smoothness of brightness transition.

[0011] 3. High-precision compensation, stable and reliable: The introduction of a PID dynamic compensation module to fine-tune the drive current in real time significantly reduces current fluctuations and reduces brightness flicker caused by unstable current at the source, especially under low brightness conditions.

[0012] 4. Self-learning and continuous optimization: The integrated machine learning module can learn users' personal preferences, enabling the system to continuously optimize its adjustment strategies over time and improve user experience. Attached Figure Description

[0013] Figure 1 This is a schematic block diagram of a low flicker adaptive backlight control device provided in an embodiment of the present invention; Figure 2 This is a circuit diagram of the ambient light sensor in the multi-source sensing collaboration module of one embodiment of the present invention; Figure 3 This is a working logic diagram of a dynamic threshold dual dimming drive unit provided in an embodiment of the present invention; Figure 4 A flowchart of a low-flicker adaptive backlight control method provided in an embodiment of the present invention. Detailed Implementation

[0014] The specific embodiments and examples of the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described are only used to explain the present invention and are not intended to limit the specific embodiments of the present invention.

[0015] refer to Figure 1The low flicker adaptive backlight control device in this embodiment mainly includes a multi-source sensing collaboration module 100, a main control processing unit 200, a dynamic threshold dual dimming drive unit 300, a backlight module 400, and a storage unit 500; each module is electrically connected in sequence, and the storage unit 500 communicates bidirectionally with the main control processing unit 200.

[0016] Specifically, the multi-source sensing collaboration module 100 integrates three types of acquisition units to achieve synchronous acquisition of multi-dimensional data; such as Figure 2 As shown, the ambient light sensor 110 consists of a high-resolution photodiode D1 (photoelectric conversion efficiency ≥0.8A / W, response time ≤10μs; such as Vishay's BPW34) and a 100KΩ voltage divider resistor R1. This circuit is connected between a 5V DC power supply VCC and ground GND, with its midpoint output signal sent to the analog input port (such as ADC1) of the main control processing unit 200. This design can linearly convert ambient light intensity from 0.1 to 100,000 Lx into a voltage signal from 0.05 to 2.5V, ensuring the acquisition accuracy in low-light environments. The screen content brightness acquisition unit 120 is integrated into the display driver and extracts data frame by frame (such as 60fps). The image's 32-level brightness histogram calculates the average and maximum brightness by statistically analyzing pixel proportions, with sampling delay controlled within 10ms. The human eye state detection unit 130 utilizes the device's front-facing camera to perform facial key point detection based on the Haar feature classifier in the OpenCV library or the more advanced Dlib library. It then extracts features such as pupil center distance and blink frequency to determine viewing distance (near distance <30cm, medium distance 30~50cm, far distance >50cm) and eye fatigue level (blink frequency <5 times / minute for severe fatigue, 5~15 times / minute for mild fatigue, and >15 times / minute for no fatigue), providing human-adaptive parameters for brightness adjustment.

[0017] Specifically, the main control processing unit 200 can be an embedded microprocessor with high-speed analog-to-digital conversion capabilities, such as the Junzheng JZ4740, which has a 12-bit precision analog-to-digital converter (ADC). This unit integrates multiple software functional modules, including a multi-parameter linkage mapping algorithm module 210, a PID dynamic compensation module 220, and a machine learning module 230. The multi-parameter linkage mapping algorithm module 210 adopts a scenario-based weighted fusion model, with initial weight allocation as follows: ambient light 0.5, screen content 0.3, and human body state 0.2. This weight can be dynamically adjusted according to the usage scenario. For example, when a "reading" scenario is detected, the weight of the human body state is increased to 0.3 to prioritize eye comfort; in a "game" scenario, the weight of the screen content is increased to 0.4 to adapt to the brightness requirements of dynamic images. The PID dynamic compensation module 220... Using fixed parameters (Kp=2.5, Ki=0.1, Kd=0.05), the module monitors the current feedback signal from the drive unit 300 in real time. When the detected current fluctuation exceeds ±0.02mA, the module outputs a correction command within 5ms to adjust the PWM duty cycle or reference voltage to ensure that the actual output brightness is consistent with the target value. The machine learning module 230 uses a logistic regression model and opens a training data area in the storage unit 500 to record the user's manual brightness adjustment records in different scenarios. The training samples include 1000 sets of user manual adjustment data in different scenarios (ambient light, user status), with ≥500 iterations. When the cumulative number of manual adjustment records in the same scenario reaches 3, the module starts the training process (iterations ≥500), updates the brightness mapping curve and weight coefficients, and achieves personalized adaptation.

[0018] Specifically, the dynamic threshold dual dimming drive unit 300 is the key hardware for achieving low flicker in this invention. It includes a PWM dimming module 310 and a DC-like dimming module 320. Its core innovation lies in the dynamic adjustment mechanism of the dimming switching threshold; combined with Figure 3As shown, the initial switching threshold is set to 50 nits. When the ambient light change rate calculated by the main control processing unit 200 is greater than 50 Lx / ms (e.g., when a user quickly moves from indoors to outdoors), the switching threshold is temporarily raised to 60 nits to avoid flickering caused by frequent switching between PWM and DC-like modes at brightness boundaries, thus extending the PWM dimming range. When the user is detected to be in a state of severe fatigue, the switching threshold is lowered to 40 nits, and the more eye-friendly DC-like dimming mode is activated first. In the high brightness range (above the dynamic threshold), the PWM dimming module 310 operates, and the frequency decreases linearly from 500Hz to 200Hz as the brightness decreases, in order to balance switching losses and flicker suppression effects. In the low brightness range (below or equal to the dynamic threshold), the system switches to the DC-like dimming module 320. This module uses a constant current source composed of a high-precision digital-to-analog converter (DAC) and an operational amplifier to provide 12-bit resolution (4096 levels) current adjustment, ensuring that the adjustment step size in the low current range (such as 0-2mA) is no greater than 0.05mA, thereby eliminating screen flicker caused by sudden current changes. This drive unit communicates with the main control processing unit 200 through an I²C interface at a communication rate of no less than 1MHz, receiving brightness control commands in real time and feeding back current status data.

[0019] Specifically, the backlight module 400 adopts a side-lit LED array, with each string of LEDs driven by an independent constant current branch of the dynamic threshold dual dimming drive unit 300. The rated current is 10mA, and the maximum brightness can reach 500 nits, ensuring the consistency of luminous intensity. The storage unit 500 uses an SPI Flash memory (such as Winbond's W25Q128) with a capacity of not less than 128KB to store multiple sets of scene-based brightness mapping curves, dynamic dimming threshold parameters, user preference data, and machine learning model parameters, supporting power-off saving and online updates.

[0020] refer to Figure 4 Based on the aforementioned low-flicker adaptive backlight control device, this invention also proposes a low-flicker adaptive backlight control method, the specific steps of which are as follows: Step S610: After the device is started, the multi-source sensing collaboration module 100 synchronously collects ambient light voltage signals, screen image brightness data and human eye status information at a period of 50ms, and transmits them to the main control processing unit 200. Step S620: The main control processing unit 200 performs 12-bit ADC sampling on the ambient light voltage signal and, combined with the light intensity-brightness correspondence table pre-stored in the storage unit 500, obtains the ambient light reference brightness value L_env; simultaneously, it determines the comfortable brightness offset value ΔL based on the eye state (no fatigue +5 nits, mild fatigue 0 nits, severe fatigue -8 nits); subsequently, the multi-parameter linkage mapping algorithm module 210 calculates the target brightness value L_target; for example: ambient light intensity 10Lx (corresponding to reference brightness value 10 nits), average screen brightness 20 nits, user no fatigue at close range (offset value +5 nits), calculated according to the initial weights: L_target=(10×0.5)+(20×0.3)+(5×0.2)=12nits; Step S630: The main control processing unit 200 calculates the current ambient light change rate and, in combination with the human fatigue state, dynamically adjusts the dimming switching threshold T_switch; then, it determines the relationship between the target brightness value L_target and the threshold T_switch to decide whether to use PWM dimming or DC-like dimming, and generates the corresponding dimming mode control command output. Step S640: The dynamic threshold dual dimming drive unit 300 receives the control command and starts the corresponding dimming mode; the brightness adjustment rate is controlled at ≤10 nits / ms, and in the low brightness range (such as below 30 nits), the rate is further reduced to ≤2 nits / ms to achieve a smooth transition. Step S650: During the adjustment process, the PID dynamic compensation module 220 monitors the drive current in real time. Once it detects a fluctuation exceeding ±0.02mA, it immediately outputs a correction amount to ensure current stability. Step S660: During continuous system operation, if the user is dissatisfied with the automatically adjusted brightness and manually adjusts it, the machine learning module 230 will record the current scene parameters (ambient light, screen content, user status) and the brightness value manually set by the user. The training samples include 1000 sets of user manual adjustment data under different scenes (ambient light, user status), with ≥500 iterations. When the cumulative number of manual records in the same scene reaches 3, the module automatically starts training, updates the mapping curve and weights, completes one personalized learning cycle, and achieves personalized adaptation.

[0021] It should be understood that the above description is only a preferred embodiment of the present invention and is not sufficient to limit the technical solution of the present invention. For those skilled in the art, within the spirit and principles of the present invention, additions, subtractions, substitutions, transformations or improvements can be made based on the above description, and all such additions, subtractions, substitutions or improvements should fall within the protection scope of the appended claims of the present invention.

Claims

1. A low-flicker adaptive backlight control device, characterized in that, include: A multi-source sensing collaboration module (100) is used to simultaneously collect ambient light intensity, screen content brightness information and user eye status information; The main control processing unit (200) is electrically connected to the multi-source sensing collaboration module (100) and is used to receive the multi-dimensional parameters and calculate the target brightness value based on the multi-parameter linkage mapping algorithm. The dynamic threshold dual dimming drive unit (300) is electrically connected to the main control processing unit (200) and is used to selectively activate the PWM dimming mode or the DC dimming mode to drive the backlight module (400) according to the target brightness value and the dynamically adjusted dimming switching threshold. The backlight module (400) is electrically connected to the dynamic threshold dual dimming drive unit (300); The storage unit (500) communicates bidirectionally with the main control processing unit (200) and is used to store brightness mapping curves, dimming threshold parameters and user preference data.

2. The low flicker adaptive backlight control device according to claim 1, characterized in that, The multi-source sensing collaboration module (100) includes: An ambient light sensor (110) consists of a high-resolution photodiode and a voltage divider circuit to convert ambient light intensity of 0.1~100000Lx into a voltage signal of 0.05~2.5V. The screen content brightness acquisition unit (120) is used to extract the brightness histogram information of the image frame by frame and calculate the average brightness value and the maximum brightness value of each frame image; The human eye condition detection unit (130) collects eye images through a camera and extracts the pupil center distance and blink frequency based on image recognition technology to determine the viewing distance and eye fatigue level.

3. The low flicker adaptive backlight control device according to claim 1, characterized in that, The main control processing unit (200) includes: The multi-parameter linkage mapping algorithm module (210) adopts a scenario-based weighted fusion model to assign initial weights to ambient light, screen content brightness and human body state parameters, and can dynamically adjust the weights of each parameter according to the usage scenario. The PID dynamic compensation module (220) is used to monitor the fluctuation of the drive current in real time and output correction instructions to keep the current stable. The machine learning module (230) is used to train and update the brightness mapping curve and weight coefficients in the multi-parameter linkage mapping algorithm module (210) based on the user's manual adjustment records.

4. The low flicker adaptive backlight control device according to claim 3, characterized in that: The PID dynamic compensation module (220) has a proportional coefficient Kp=2.5, an integral coefficient Ki=0.1, a derivative coefficient Kd=0.05, and a correction response time ≤5ms.

5. The low flicker adaptive backlight control device according to claim 1, characterized in that, The dynamic threshold dual dimming drive unit (300) includes: The PWM dimming module (310) is used for dimming in the high brightness range, and its frequency decreases linearly from 500Hz to 200Hz as the brightness decreases. A DC-like dimming module (320) is used for dimming in the low brightness range, and the adjustment step size is ≤0.05mA through 12-bit high-precision current adjustment. The dimming switching threshold is dynamically adjusted based on the rate of change of ambient light and the degree of eye fatigue experienced by the user.

6. The low flicker adaptive backlight control device according to claim 5, characterized in that, When the ambient light change rate is greater than 50 Lx / ms, the dimming switching threshold increases; when the user is in a state of severe fatigue, the dimming switching threshold decreases.

7. The low flicker adaptive backlight control device according to claim 1, characterized in that: The backlight module (400) adopts a side-lit LED array, and each string of LEDs is equipped with an independent constant current control branch.

8. A low-flicker adaptive backlight control method based on the device according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1: The ambient light intensity, screen content brightness information and user eye status information are collected synchronously through the multi-source sensing collaboration module (100); S2: The main control processing unit (200) calculates the target brightness value based on the collected multi-dimensional parameters through a multi-parameter linkage mapping algorithm; S3: The main control processing unit (200) dynamically adjusts the dimming switching threshold according to the rate of change of ambient light and the degree of eye fatigue of the user, and determines the dimming range to which the target brightness value belongs; S4: The dynamic threshold dual dimming drive unit (300) starts the corresponding PWM dimming mode or DC dimming mode according to the instruction, and adjusts the brightness at a preset rate; S5: The PID dynamic compensation module (220) monitors the drive current in real time and corrects abnormal fluctuations immediately.

9. The low flicker adaptive backlight control method according to claim 8, characterized in that, In step S2, when calculating the target brightness value, a comfortable brightness offset value determined based on the user's eye fatigue level is also introduced.

10. The low flicker adaptive backlight control method according to claim 8, characterized in that, After step S4, step S6 is also included: if the user performs manual brightness correction, the current scene parameters and manual adjustment values ​​are recorded by the machine learning module (230), and the brightness mapping curve and weight coefficient are updated after the preset conditions are met.

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