Mini LED backlight brightness control system applied to display equipment

Abstract

The invention relates to the technical field of backlight brightness control, in particular to a Mini LED backlight brightness control system applied to display equipment. The future illumination change trend is predicted through MPC, and a control sequence of backlight adjustment is optimized, so that the control sequence responds to the change in a short time, and meanwhile, the severe fluctuation of brightness is reduced; the sliding mode control is introduced for robust feedback control aiming at ambient light disturbance and sensor errors, so that the system can still maintain stable brightness output under external disturbance, and the LED backlight system not only can improve the visual comfort of a user, but also realizes optimization of energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of backlight source brightness control, and in particular to a Mini LED backlight source brightness control system applied to a display device. Background Art

[0002] With the widespread application of display devices, the brightness control of LED backlight has become an important factor affecting user visual experience and energy consumption management.

[0003] Existing brightness control methods mainly use feedback adjustment strategies from ambient light sensors, but there are problems such as response lag, sudden adjustment changes, and user discomfort. In addition, most existing brightness adjustment algorithms are linear controls, which are difficult to accurately match the nonlinear perception characteristics of the human eye. This results in the brightness being adjusted too quickly or too slowly in sudden light conditions (such as when scenes are switched quickly or when external light sources change dramatically), affecting visual comfort. Secondly, the current brightness adjustment schemes are difficult to ensure robustness in complex environments and are easily affected by external interference, such as sensor errors or short-term drastic fluctuations in ambient light. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a Mini LED backlight source brightness control system applied to a display device, which can effectively solve the problem that the brightness control method of the backlight source in the prior art cannot combine the physiological characteristics of the user's eyes and environmental disturbances to improve precise control.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides a Mini LED backlight source brightness control system applied to a display device, comprising at least: Light adaptation control module, establishes a first-order dynamic model of human eye adaptation, simulates the dark adaptation and light adaptation process of the human eye, and determines the light intensity perception value adapted by the human eye The target backlight intensity is calculated to drive the brightness adjustment of the LED backlight system, which is characterized by: In calculating the target backlight intensity, visual fatigue is introduced to realize the nonlinear mapping relationship index Dynamic adjustment of Backlight closed-loop adjustment module, using MPC feedforward compensation combined with robust feedback compensation to obtain feedback adjustment , to achieve closed-loop regulation, by adjusting the feedback As input, it is used to adjust the PWM duty cycle, realize the update of the PWM duty cycle, and perform brightness control of the LED backlight system through the update.

[0006] Furthermore, the human eye adaptation model of the first-order dynamic model is specifically: in, express The light intensity perception value that the human eye adapts to, Indicates the current ambient light intensity. represents the light adaptation time constant, Indicates the current pupil diameter, Indicates blink frequency; light adaptation time constant According to the following relationship: represents the basic adaptation time constant, , They represent the corresponding adjustment coefficients respectively.

[0007] Furthermore, numerical calculation methods are used to approximate the real behavior of the basic dynamic process of human eye adaptation to light, and the adaptation process of the human eye is gradually simulated, then: in, represents the sampling period, Indicates time The light intensity perception value adapted by the human eye at this time, express The ambient light intensity at Depend on renew, Indicates the difference between the current ambient light and the light perceived by the human eye.

[0008] Further, according to the light intensity perception value The method to calculate the target backlight intensity is: Normalize the light intensity: in, represents the normalized light intensity perception value, Indicates the reference ambient light intensity, Represents the nonlinear mapping relationship index; Calculate the target backlight brightness: in, Indicates the target backlight brightness, , Respectively represent the minimum and maximum brightness values ​​of the backlight source; According to the target backlight brightness Calculate the PWM duty cycle, generate a PWM signal, and drive the LED backlight system to perform adjustments.

[0009] Furthermore, visual fatigue is introduced to realize the nonlinear mapping relationship index The dynamic adjustment is as follows: in, represents the basic index value, , , as well as They represent the corresponding weight coefficients, represents the reference pupil diameter, Indicates the user's current blinking frequency. Indicates visual fatigue index; The visual fatigue index is determined according to the following relationship: in, , as well as They represent the corresponding weight coefficients, represents the historical average pupil diameter of the user, Indicates the Theta wave level in the user's current EEG signal.

[0010] Furthermore, the specific steps of MPC feedforward compensation are: Build a dynamic model of backlight brightness changes: in, Indicates the next sampling time The predicted light intensity perception value; Constructing feedforward control compensation : Select the prediction time domain length ; Using dynamic models for prediction: Among them, according to Perform iterative calculations; Constructing the objective function : in, Indicates the prediction time domain The target backlight brightness at the moment, Indicates the prediction time domain The actual backlight brightness at the moment, Indicated in The difference between the change in the control input at a given moment and the previous control input, represents the balance factor; Solve the optimal control sequence by quadratic programming or gradient descent , output the feedforward control compensation at the current moment .

[0011] Further, the feedback control correction amount is determined according to the robust feedback compensation ,include: Define the current brightness error: in, Indicates the brightness error at the current moment, Indicates the target backlight brightness at the current moment. Indicates the actual measured target backlight brightness; Construct sliding surface: in, represents the sliding surface, represents the integral coefficient, represents the integral term of the error, represents the integral variable; Construct the sliding mode feedback control law: in, represents the feedback control correction amount, represents the robust control gain, Represents the boundary layer width parameter.

[0012] The boundary layer width parameter is determined according to the following relationship: represents a constant term, represents the gain factor, represents the absolute value of the sliding surface, represents the power exponent, represents a saturation function.

[0013] Introducing disturbance observer to realize feedback control correction The updates are: in, represents the updated feedback control correction, represents the disturbance estimate of the disturbance observer, represents the system gain; Use the disturbance observer to estimate the unknown disturbance : in, represents the time rate of change of the disturbance estimate, represents the gain parameter of the disturbance observer, Indicates the predicted backlight brightness.

[0014] According to the feedforward control compensation and the updated feedback control correction Get feedback adjustment , to achieve update optimization of PWM duty cycle.

[0015] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects: MPC predicts the lighting trend of N moments in the future and calculates the optimal backlight brightness sequence in advance, making brightness adjustment more forward-looking and reducing mutations and lags. In each sampling cycle, the optimal control sequence is solved and only the optimal control input at the current moment is applied, thereby avoiding frequent brightness adjustments and improving adjustment stability. A sliding mode error correction mechanism is adopted, and the error accumulation term is used for feedback compensation to improve the anti-interference ability to sensor measurement errors and external light fluctuations.

[0016] Through the adaptive robust control law, it can respond quickly when the lighting environment changes drastically, and ensure the stability of brightness adjustment by suppressing sliding mode jitter.

[0017] That is, MPC is used to predict future lighting change trends and optimize the control sequence of backlight adjustment, so that it can respond to changes in a short time while reducing drastic fluctuations in brightness. In response to ambient light disturbances and sensor errors, sliding mode control is introduced for robust feedback control, so that the system can maintain stable brightness output under external interference, thereby enabling the LED backlight system to not only improve the user's visual comfort, but also optimize energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is the overall module block diagram of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The present invention will be further described below in conjunction with the embodiments.

[0022] Example 1 (see Figure 1 ): A Mini LED backlight brightness control system applied to a display device, comprising at least: The light adaptation control module is used to obtain environmental condition data and eye condition data, and to build a nonlinear adaptation model of the human eye based on the environmental condition data and eye condition data, so as to guide the LED backlight system to adjust to be more in line with physiological response, as follows: The light perception of the human eye does not instantly follow the changes in ambient light. There is an adaptation process. This adaptation process is affected by pupil size and blinking frequency. The first-order dynamic model can be used to describe its changing trend: in, express The light intensity perception value that the human eye adapts to, Indicates the current ambient light intensity. Represents the light adaptation time constant (in seconds), which describes the time required for the human eye to adapt from one lighting condition to another. Indicates the current pupil diameter, represents the blinking frequency; where, for the light adaptation time constant According to the following relationship: in, represents the basic adaptation time constant, , They represent the corresponding adjustment coefficients respectively, and the fitting degree is improved by introducing the individual physiological parameters of the human eye.

[0023] Since computers cannot directly process continuous differential equations, numerical calculation methods are used to approximate the true behavior of the basic dynamic process of human eye adaptation to light, and gradually simulate the adaptation process of the human eye, then: in, Represents the sampling period, describing the time interval for updating brightness. Indicates time The light intensity perception value adapted by the human eye at this time, express The ambient light intensity at Depend on Update, indicating that the human eye's light perception is a gradual process, Indicates the difference between the current ambient light and the light perceived by the human eye, which determines the adjustment direction; Furthermore, by simulating the dynamic adaptation process of the human eye to ambient light, the subsequent brightness adjustment of the LED backlight system is made to conform to the physiological characteristics of the human eye, thereby improving visual comfort and real perception matching.

[0024] Furthermore, according to the light intensity perception value adapted by the human eye Calculate the appropriate target backlight intensity so that the LED backlight system is adjusted to meet the physiological characteristics of the human eye, including: Normalize the light intensity: in, represents the normalized light intensity perception value, Indicates the reference ambient light intensity, Represents the nonlinear mapping relationship index; It should be noted that the introduction of visual fatigue to achieve nonlinear mapping relationship index The dynamic adjustment of in, represents the basic index value, , , as well as They represent the corresponding weight coefficients, represents the reference pupil diameter, Indicates the user's current blinking frequency. represents the visual fatigue index, wherein the visual fatigue index is determined according to the following relationship: in, , as well as They represent the corresponding weight coefficients, represents the historical average pupil diameter of the user, Indicates the Theta wave level in the user's current EEG signal, by introducing the visual fatigue index Predict the user's fatigue level after using the display device for a long time and automatically adjust the brightness strategy to automatically reduce brightness fluctuations when visual fatigue occurs to protect the user's eyesight.

[0025] Calculate the target backlight brightness: in, Indicates the target backlight brightness, , Represent the minimum and maximum brightness values ​​of the backlight source respectively, and then, through nonlinear mapping, Converted into appropriate target backlight brightness, this ensures that the adjustment of screen brightness not only matches the changes in ambient light, but also conforms to the human eye's perception of brightness changes, avoiding excessive or insufficient brightness changes.

[0026] Set the target backlight brightness Converted into a PWM signal that can be used by actual hardware to drive the LED backlight source for adjustment, we have: Calculate the PWM duty cycle: in, Indicates the obtained PWM duty cycle, according to the duty cycle Generate the corresponding PW signal to drive the LED backlight module for adjustment, and convert the calculated target backlight brightness into a hardware control signal. The PWM modulation method can achieve a smooth brightness transition and prevent sudden brightness changes, thereby reducing visual discomfort and improving the display quality of the device.

[0027] The backlight closed-loop adjustment module uses MPC feedforward compensation combined with robust feedback control to achieve closed-loop adjustment. The final feedback adjustment amount As input, it is used to adjust the PWM duty cycle, implement the update of the PWM duty cycle, and ensure smooth control of the backlight brightness, including: MPC feedforward compensation uses a dynamic model to predict future outputs, obtains the optimal control sequence by solving the optimization problem in each sampling period, and outputs the feedforward control compensation at the current moment : Establish a dynamic model to describe the change of backlight brightness and provide a basis for subsequent predictions: in, Indicates the next sampling time Predicted light intensity perception value; For the feedforward control compensation ,include: Select the prediction time domain length ; Using the dynamic model for prediction, we have: in, Perform iterative calculations; Constructing the objective function , comprehensively considering the error between the future output and the target backlight brightness and the smoothness of the control signal: in, Indicates the prediction time domain The target backlight brightness at the moment, Indicates the prediction time domain The actual backlight brightness at the moment, Indicated in The change in the control input at a given moment is the difference between the previous control input and the Represents the balance factor, which adjusts the weight of the error term and the control input change term; Solve the optimal control sequence by quadratic programming or gradient descent (not described here) , output the feedforward control compensation at the current moment ,MPC feedforward compensation optimizes the control input in advance by predicting future outputs, thereby reducing the lag and overshoot caused by environmental changes.

[0028] Based on the MPC feedforward compensation, the feedback control correction is defined by compensating for inaccuracies, disturbances and noise through robust feedback. ,include: Define the current brightness error: in, Indicates the brightness error at the current moment, Indicates the target backlight brightness at the current moment. Indicates the actual measured target backlight brightness; Construct sliding surface: in, represents the sliding surface, which is used to ensure error convergence. Indicates the integral coefficient, regulating the influence of error accumulation, represents the integral term of the error, represents the integral variable, , describing the time The error from 0 to the current time The integral of , that is, the accumulated value of the error over time, enables the sliding surface to converge to the expected brightness more quickly during the control process, while reducing the impact of long-term errors; Furthermore, the sliding mode feedback control law is constructed: in, represents the feedback control correction amount, Represents the robust control gain (positive value), which determines the compensation strength. represents the boundary layer width parameter, which is used to prevent high-frequency switching of the sliding mode controller, where , represents a constant term, which represents the minimum boundary layer size of the sliding mode control. That is, when the error is very small, the boundary layer of the sliding mode control will not shrink infinitely. Represents the gain coefficient, which controls the dynamic adjustment rate of the boundary layer width parameter when the error is large. Represents the absolute value of the sliding surface, increasing The adaptability of the sliding mode control is used to achieve a balance between fast convergence and chattering suppression, thereby improving the overall performance of the sliding mode control. represents the power exponent, represents the saturation function, which is used to avoid severe chattering of the control signal. , represents the input variable, usually a sliding surface or a control error signal, represents a symbolic function; Furthermore, if the disturbance is large, it will affect the retention of the sliding mode surface, causing the LED backlight system to deviate from the ideal trajectory. In addition, under high-frequency disturbances, the sliding mode control is prone to jitter because its control signal will switch frequently. Therefore, the introduction of the disturbance observer enhances the anti-disturbance ability of the sliding mode control, reduces the advantage of jitter, and realizes the feedback control correction. The updates are: in, represents the updated feedback control correction, represents the disturbance estimate value estimated by the disturbance observer (used to compensate for external disturbances in real time), Represents the gain of the system (describing how the control input affects brightness).

[0029] In order to estimate the unknown disturbance , using a disturbance observer: in, represents the time rate of change of the disturbance estimate, that is, how the disturbance estimate changes over time, represents the gain parameter of the disturbance observer, which is used to adjust the dynamic response speed of the disturbance estimation (affecting the convergence speed of the observer). Indicates the actual state of the LED backlight system, that is, the actual measured target backlight brightness. It indicates the predicted backlight brightness (the brightness level that the entire LED backlight system should reach under ideal conditions, that is, without disturbance), that is, the state that should be achieved under ideal conditions. Therefore, if there is and If they are not equal, it means that there is an external disturbance (such as changes in ambient light) affecting the brightness. The disturbance observer will adjust the control input through error compensation to make the actual brightness as close as possible to the predicted backlight brightness.

[0030] The robust feedback compensation module corrects the current error in real time, achieves rapid error convergence through sliding mode control, compensates for deviations caused by inaccurate modeling, external disturbances and noise, and ensures a smoother and more stable backlight output.

[0031] Therefore, the feedforward control compensation and the updated feedback control correction Add together to get the final feedback adjustment (As the incremental adjustment amount of PWM, the actual target backlight brightness Approximately predict the backlight brightness, while improving the robustness and stability of the entire LED backlight system), realize the update optimization of PWM duty cycle, and Converted into PWM signal to control LED backlight, then: in, Indicates the current PWM duty cycle after update, Indicates the PWM duty cycle at the previous moment, that is, the historical duty cycle value. Through incremental adjustment, PWM can achieve smooth transition, avoid visual discomfort caused by sudden brightness changes, and improve control stability.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Mini LED backlight brightness control system for a display device, comprising: Light adaptation control module, establishes a first-order dynamic model of human eye adaptation, simulates the dark adaptation and light adaptation process of the human eye, and determines the light intensity perception value adapted by the human eye The target backlight intensity is calculated to drive the brightness adjustment of the LED backlight system, which is characterized by: In calculating the target backlight intensity, visual fatigue is introduced to realize the nonlinear mapping relationship index Dynamic adjustment of Backlight closed-loop adjustment module, using MPC feedforward compensation combined with robust feedback compensation to obtain feedback adjustment , to achieve closed-loop regulation, by adjusting the feedback As input, it is used to adjust the PWM duty cycle, realize the update of the PWM duty cycle, and perform brightness control of the LED backlight system through the update.

2. According to claim 1, a Mini LED backlight brightness control system for a display device is characterized in that: The human eye adaptation model of the first-order dynamic model is specifically: ； in, express The light intensity perception value adapted by the human eye at this time, Indicates the current ambient light intensity. represents the light adaptation time constant, Indicates the current pupil diameter, Indicates blink frequency; light adaptation time constant According to the following relationship: ； represents the basic adaptation time constant, , They represent the corresponding adjustment coefficients respectively.

3. The Mini LED backlight brightness control system for a display device according to claim 2, characterized in that: The numerical calculation method is used to approximate the real behavior of the basic dynamic process of human eye adaptation to light, and the adaptation process of the human eye is gradually simulated, then: in, represents the sampling period, Indicates time The light intensity perception value at express The ambient light intensity at Depend on renew, Indicates the difference between the current ambient light and the light perceived by the human eye.

4. The Mini LED backlight brightness control system for a display device according to claim 3, characterized in that: According to the light intensity perception value The method to calculate the target backlight intensity is: Normalize the light intensity: ； in, represents the normalized light intensity perception value, Indicates the reference ambient light intensity, Represents the nonlinear mapping relationship index; Calculate the target backlight brightness: ； in, Indicates the target backlight brightness, , Respectively represent the minimum and maximum brightness values ​​of the backlight source; According to the target backlight brightness Calculate the PWM duty cycle, generate a PWM signal, and drive the LED backlight system to perform adjustments.

5. The Mini LED backlight brightness control system for a display device according to claim 4, characterized in that: Introducing visual fatigue to achieve nonlinear mapping relationship index The dynamic adjustment is as follows: in, represents the basic index value, , , as well as They represent the corresponding weight coefficients, represents the reference pupil diameter, Indicates the user's current blinking frequency. Indicates visual fatigue index; The visual fatigue index is determined according to the following relationship: ； in, , as well as They represent the corresponding weight coefficients, represents the historical average pupil diameter of the user, Indicates the Theta wave level in the user's current EEG signal.

6. The Mini LED backlight brightness control system for a display device according to claim 5, characterized in that: The specific steps of the MPC feedforward compensation are: Build a dynamic model of backlight brightness changes: ； in, Indicates the next sampling time The predicted light intensity perception value; Constructing feedforward control compensation : Select the prediction time domain length ; Using dynamic models for prediction: ； Among them, according to Perform iterative calculations; Constructing the objective function : ； in, Indicates the prediction time domain The target backlight brightness at the moment, Indicates the prediction time domain The actual backlight brightness at the moment, Indicated in The difference between the change in the control input at a given moment and the previous control input, represents the balance factor; Solve the optimal control sequence by quadratic programming or gradient descent , output the feedforward control compensation at the current moment .

7. The Mini LED backlight brightness control system for a display device according to claim 6, characterized in that: Determining the feedback control correction amount based on robust feedback compensation ,include: Define the current brightness error: ； in, Indicates the brightness error at the current moment, Indicates the target backlight brightness at the current moment. Indicates the actual measured target backlight brightness; Construct sliding surface: ； in, represents the sliding surface, represents the integral coefficient, represents the integral term of the error, represents the integral variable; Construct the sliding mode feedback control law: ； in, represents the feedback control correction amount, represents the robust control gain, Represents the boundary layer width parameter.

8. The Mini LED backlight brightness control system for a display device according to claim 7, characterized in that: The boundary layer width parameter is determined according to the following relationship: ； represents a constant term, represents the gain factor, represents the absolute value of the sliding surface, represents the power exponent, represents a saturation function.

9. The Mini LED backlight brightness control system for a display device according to claim 8, characterized in that: Introducing disturbance observer to realize feedback control correction The updates are: ； in, represents the updated feedback control correction, represents the disturbance estimate of the disturbance observer, represents the system gain; Use the disturbance observer to estimate the unknown disturbance : ； in, represents the time rate of change of the disturbance estimate, represents the gain parameter of the disturbance observer, Indicates the predicted backlight brightness.

10. The Mini LED backlight brightness control system for a display device according to claim 9, characterized in that: According to the feedforward control compensation and the updated feedback control correction Get feedback adjustment , to achieve update optimization of PWM duty cycle.

Images