Dimming Control System for Flicker-Free Analog-Digital Transition
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Solution Overview
Problem
Existing dimming control systems face issues with flickering during transitions between analog and digital dimming, instability at low brightness, and non-linear backlight control, particularly due to the limitations of PWM dimming and hybrid approaches that fail to address instantaneous voltage shortages and step-like variations.
Innovation Solution
A dimming control optimization system that employs a light-emitting sampling module, integrator, error amplifying module, comparator, and power supply transitioning module to generate a dimming signal synchronized with a finite-peak periodic continuous wave input signal, allowing seamless transition between analog and digital dimming modes without flickering, using the same compensation voltage for medium and high brightness and fixed-frequency digital dimming for low brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If analog dimming is used for low brightness control, then the control stability is improved, but the color temperature consistency deteriorates
Solution Approach 1:
The patent divides the dimming range into multiple segments: analog dimming is used for high to medium brightness ranges where color temperature consistency is less critical, while digital PWM dimming is used for low brightness ranges where color temperature consistency is maintained. This segmentation allows each dimming method to operate in its optimal range, resolving the contradiction between control stability and color temperature consistency.
2Illumination intensity
If digital dimming with PWM is used for low brightness, then the color temperature consistency is improved, but flickering occurs during mode transition
Solution Approach 1:
The patent implements dynamic switching between analog and digital dimming modes based on the current brightness level. The switching threshold is dynamically adjusted to ensure smooth transition without flickering. The system monitors the dimming state and automatically selects the appropriate dimming method, making the transition dynamic and adaptive rather than static, thereby eliminating flickering while maintaining color temperature consistency.
Solution Approach 2:
The patent introduces an intermediary control mechanism that manages the transition between analog and digital dimming modes. This intermediary layer includes a control unit that detects the current brightness level and smoothly switches between dimming methods, preventing direct abrupt transitions that cause flickering. The intermediary ensures stable mode switching while maintaining the benefits of both dimming approaches.
3Adaptability or versatility
If hybrid dimming is used to balance low brightness control and efficiency, then the advantages of both analog and digital dimming are obtained, but step-like variations occur during mode switching
Solution Approach 1:
The patent applies preliminary action by pre-setting the switching threshold between analog and digital dimming modes. Before the actual switching occurs, the system prepares by monitoring the brightness level approaching the threshold and initiates a smooth transition sequence. This preliminary preparation prevents abrupt step-like variations by ensuring the transition is planned and controlled in advance, maintaining brightness continuity while preserving the flexibility of hybrid dimming.
4Object-affected harmful factors
If PWM dimming frequency is reduced to avoid audible noise, then the noise is eliminated, but flickers become observable
Solution Approach 1:
The patent segments the brightness control into two distinct ranges: for medium to high brightness levels, analog dimming is used which produces no audible noise and no flicker; for low brightness levels, digital PWM dimming is used with a frequency optimized to avoid both audible noise and visible flicker. This segmentation allows the system to avoid the noise-flicker tradeoff by using the appropriate dimming method for each brightness range.
Data Source
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AI summary
A dimming control optimization system includes a light-emitting sampling module, an integrator module, an error amplifying module, a comparator module, a dimming module, and a power supply converting module. The light-emitting sampling module obtains and transmits a brightness signal of an illuminator to the integrator. The integrator module integrates the brightness signal to generate a direct-current (DC) sampling signal. The error amplifying module receives the sampling signal and an external dimming reference voltage to generate an output compensation voltage signal. The comparator module determines if the output signal from the error amplifying module has reached a transitioning threshold and output the compensation voltage of the error amplifying module or a threshold voltage as a control reference signal. The dimming module receives the control reference signal and a finite-peak periodic continuous wave input signal to generate a dimming signal to be sent to the power supply converting module. The power supply transitioning module synchronizes the control reference signal and the dimming signal to allow the dimming control optimization system to control analog dimming of the illuminator for medium and high brightness and to enter into a fixed-frequency digital dimming for low brightness without transition gaps during the transitioning between the two dimming modes.