LED Driver Dithering for Flicker-Free Color Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lighting systems experience visible flashes or flicker when switching between hybrid and PWM driving schemes due to changes in impedance, leading to user confusion and reduced confidence.
Innovation Solution
Implement a dithering procedure that rapidly switches between hybrid and PWM driving schemes to mitigate the visible flash, utilizing a controller to manage transitions and adjust duty cycles to maintain color consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switching between hybrid and PWM driving schemes is implemented to provide color tuning options, then color versatility is improved, but visible flash and user experience deteriorate
Solution Approach 1:
The patent applies periodic action by implementing dithering that rapidly alternates between hybrid and PWM driving schemes at frequencies above human visual perception (greater than 20 Hz). This periodic switching creates the perception of a stable intermediate color while actually cycling between two driving modes, thereby eliminating visible flash during color transitions.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that the dithering process operates continuously at high frequency, creating a seamless visual output. The rapid alternation between driving schemes is perceived as a continuous stable color by the human eye, eliminating the discontinuous flash effect that would occur with slower or single-mode switching.
2Object-affected harmful factors
If dithering between driving schemes is implemented to reduce visible flash, then user experience is improved, but system complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the current driving scheme and color output, then dynamically adjusting the dithering parameters to maintain the desired color point. The controller receives feedback about the operational state and automatically modifies the switching strategy, eliminating the need for complex manual intervention while maintaining color accuracy during dithering transitions.
3Object-affected harmful factors
If rapid switching between driving schemes is performed to eliminate flash, then flicker reduction is achieved, but energy management complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the duty cycles of both hybrid and PWM modes during dithering to maintain a constant average color output. The controller modifies electrical parameters (duty cycle percentages, switching frequencies) in real-time based on the target color point, ensuring energy efficiency is maintained while eliminating flicker during transitions between color regions.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A light-emitting apparatus can reduce flicker and retain power efficiency. A method can include driving, by a light emitting element (LEE) driver circuit, first, second, and third LEEs using a pulse width modulation (PWM) driving scheme to generate light of a first color, the first, second, and third LEEs configured to emit different colors, alternating, by the LEE driver circuit, between driving the first, second, and third LEEs using a hybrid driving scheme and the PWM driving scheme, and after alternating between driving the first, second, and third LEEs in the hybrid and PWM driving schemes, driving, by the LEE driver circuit, the first, second, and third LEEs using the hybrid driving scheme.