Grouped Light Fixture Dimming for Smooth Near-Zero Brightness
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Solution Overview
Problem
Existing light fixture systems face limitations in achieving smooth, continuous dimming between minimum non-zero intensity and zero intensity due to finite pulse-width modulation, resulting in discrete intensity steps that are perceptible to human observers.
Innovation Solution
A light fixture system with groups of light sources controlled by a controller that rapidly switches groups on and off within short time intervals, allowing for continuous intensity adjustment by alternating group activation, achieving stable and homogeneous dimming effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse-width modulation (PWM) is used to dim light fixtures, then the minimum intensity can be controlled, but the intensity changes in discrete steps and cannot achieve smaller increments between minimum non-zero and zero intensity
Solution Approach 1:
The patent segments the light fixture system into multiple independently controllable groups of light sources. By controlling each group separately and switching them on/off in a staggered sequence, the system achieves finer intensity steps than traditional PWM. For example, with 10 groups, the system can create 10 distinct intensity levels by activating different combinations of groups, effectively multiplying the dimming resolution beyond what single-group PWM can achieve.
Solution Approach 2:
The patent implements periodic switching of light source groups in a cyclic sequence. Each group is activated for a specific duration followed by a pause, creating a periodic on/off pattern. This periodic action across multiple groups produces an average intensity that can be precisely controlled. The duty cycle of each group's periodic switching contributes to the overall dimming effect, enabling smooth transitions between intensity levels.
2Measurement precision
If groups are switched on and off rapidly to achieve fine dimming steps, then smaller intensity steps are enabled, but the switching frequency must be high enough to remain imperceptible to the human eye and high-speed cameras
Solution Approach 1:
The patent transitions from temporal dimming control (single PWM channel) to spatial-temporal control by adding the dimension of multiple parallel light source groups. Instead of varying the duty cycle of a single group at high frequency, the system distributes the dimming control across multiple groups activated at different times. This dimensional expansion allows the system to achieve fine intensity resolution through temporal sequencing of spatially separated groups, reducing the required switching frequency for each individual group.
3Stability of the object's composition
If multiple groups are switched in succession with short intervals, then homogeneous dimming is achieved, but the control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the switching sequence and timing parameters for all light source groups before actual operation. The control system stores predetermined timing information that specifies when each group should be activated and for how long. This preliminary configuration allows the system to execute complex multi-group switching patterns without real-time computational overhead, maintaining perceived homogeneity while managing control complexity through offline optimization.
Data Source
AI summary
Techniques for high-resolution dimming include a light fixture having a plurality of light sources arranged in a plurality of groups, wherein each group comprises one or more light sources. The plurality of groups are controlled so that each of the groups is repeatedly switched on and off according to a repeating pattern, the repeating pattern including at least three different combinations of which of the plurality of groups is switched on and which of the plurality of groups is switched off. Each of the at least three different combinations is repeated at least once every 1/10 s.