LED Dimming Control System Reducing Flicker via Segmented Amplitude and PWM Strategies
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Solution Overview
Problem
Existing dimming technologies for light emitting arrangements often introduce flicker or ripple effects, which are undesirable and can affect user experience.
Innovation Solution
A dimming control system that employs different strategies based on desired dimming levels, using amplitude control for initial dimming and pulse width modulation for higher dimming levels, minimizing apparent flicker and maintaining color consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pulse width modulation is used to control dimming level, then dimming control is achieved, but flicker and ripple effects are introduced into output light
Solution Approach 1:
The dimming range is segmented into two distinct ranges: a first dimming range (higher light output) and a second dimming range (lower light output). Different control strategies are applied to each segment - amplitude control for the first range and pulse width modulation for the second range - to optimize performance and minimize flicker in each segment
Solution Approach 2:
The control strategy changes parameters based on the operating point. When transitioning from the first dimming range to the second dimming range, the system switches from amplitude control to pulse width modulation, and adjusts the pulse frequency to be above the flicker fusion threshold, thereby eliminating perceptible flicker
2Ease of operation
If amplitude control is used for initial dimming, then dimming control is achieved, but color shifting may occur
Solution Approach 1:
The dimming operation is divided into two phases: initial dimming using amplitude control, and lower-level dimming using pulse width modulation. This segmentation allows each phase to use the most appropriate control method for maintaining color consistency at that operating range
Solution Approach 2:
The system performs preliminary amplitude control to transition from maximum brightness to the threshold of the second dimming range, establishing a stable starting point before applying pulse width modulation. This preliminary action ensures smooth transition and maintains color consistency throughout the dimming process
Data Source
AI summary
A mechanism for controlling a dimming level of a light emitting arrangement. During initial dimming, the dimming level is controlled by controlling a maximum amplitude of current that can be drawn by any light emitting modules of a light emitting arrangement. During higher levels of dimming (for lower light intensities), the dimming level is controlled using a pulse width modulation strategy.