LED Lighting Fixture with Incandescent Dimming Characteristics
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Solution Overview
Problem
LED lighting systems do not replicate the dimming characteristics of incandescent light sources, as the color temperature of LEDs does not change significantly when dimmed, unlike incandescent bulbs which shift towards warmer colors, leading to a less natural color rendering index (CRI) and unsatisfactory color appearance.
Innovation Solution
A dimmable LED lighting system utilizing three or more LED light sources with different spectral power distribution (SPD) curves, driven at predefined power ratios to model an incandescent-style dimming color curve, achieving a high CRI and simulating the color temperature shift of incandescent bulbs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional LED light sources are used for lighting, then energy efficiency and reliability are improved, but the dimming color characteristics are worsened (no color temperature shift occurs)
Solution Approach 1:
The patent combines multiple LED light sources with different spectral power distribution characteristics (first LED with peak at 450nm, second LED with peak at 530nm, third LED with peak at 610nm) to create a composite light source that mimics incandescent dimming behavior. By merging these different LED types and controlling their relative intensities, the system achieves both energy efficiency and authentic color temperature shifting during dimming.
Solution Approach 2:
The system dynamically changes the operational parameters (current ratios) of different LED types based on the desired dimming level. At full brightness, the blue LED dominates; as dimming progresses, the amber and red LEDs are progressively activated to shift the overall color temperature, replicating the black body locus curve of incandescent bulbs without sacrificing LED efficiency.
2Measurement precision
If individual drivers are used to control each colored LED separately, then color control precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the control functions for multiple LED channels into a single LED driver that provides multiple output channels. This single driver simultaneously controls the intensity ratios of different LED types, achieving precise color control while avoiding the complexity of multiple separate driver units.
Solution Approach 2:
The LED driver is designed with multi-functionality, serving as a universal control unit that manages multiple LED channels with different spectral characteristics. This single device performs the functions of what would traditionally require separate drivers, reducing system complexity while maintaining precise control over the mixed LED output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves a high general color rendering index (CRI) of over 80 and 90 in specific configurations, with a value of R9 greater than 50, effectively mimicking incandescent-style dimming by adjusting the power ratios across channels, ensuring a natural color appearance throughout the dimming region.
Implementation Method 1
Light Emitting Diodes (LEDs) have begun to replace traditional incandescent light sources in lighting fixtures
Implementation Method 2
Blue LEDs with a phosphor coating are typically used to produce white light
Implementation Method 3
an LED driver to selectively supply current to each of the LED light sources on first, second and third channels, respectively
Data Source
AI summary
A dimmable LED lighting system includes first, second and third types of LED light sources, and an LED driver to control the supply of current on first, second and third channels, respectively to the first, second and third types of LED light sources. The first, second and third types of LED light sources are selected according to their spectral power distribution (SPD) curves. The selected SPD curves together model a dimming color curve that is characteristic of an incandescent light source when the first, second and third types of LED light sources are separately driven with current at predefined power ratios that correspond to dimming levels over a dimming region of the dimming color curve. The dimmable LED lighting system can have a color rendering index Ra greater than 80 over the dimming region.