Tunable White Light LED Strings with High Color Rendering
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Solution Overview
Problem
Existing LED lamps struggle to provide white light across a range of correlated color temperatures (CCT) while maintaining high efficiency, luminous flux, and good color rendering with acceptable color stability.
Innovation Solution
The use of multiple LED strings with different luminescent materials and a drive circuit that adjusts the relative drive currents to combine unsaturated lights within specific color ranges, allowing for tunable white light generation across a broad CCT range with high color rendering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LEDs of different colors are used to generate white light, then the correlated color temperature range can be adjusted, but the color rendering performance deteriorates due to gaps in spectral power distribution
Solution Approach 1:
The patent divides the white light generation into multiple independent LED strings, each emitting a specific color range (blue, cyan, yellow-green, red). By segmenting the spectral coverage into distinct regions and combining them, the system achieves both broad CCT adjustability and continuous spectral power distribution for high color rendering.
Solution Approach 2:
The patent combines multiple LED types with different spectral characteristics (blue LED, cyan LED, yellow-green LED, red LED) into a composite light emitting system. This composite approach creates a unified white light source with tunable color temperature and superior color rendering by filling spectral gaps that would exist in single-LED or simple multi-LED combinations.
2Productivity
If LED drive currents are increased to improve luminous flux, then the light output increases, but color stability deteriorates
Solution Approach 1:
The patent implements dynamic control of drive currents to each LED string based on desired operating parameters. The system can dynamically adjust current distribution among blue, cyan, yellow-green, and red LED strings to maintain optimal color rendering and color stability across varying luminous flux requirements, preventing color shifts that would occur with simple proportional scaling.
Solution Approach 2:
The patent changes the electrical parameters (drive currents) of individual LED strings independently to achieve desired optical output characteristics. By adjusting the current ratios among different color LEDs rather than uniformly increasing all currents, the system maintains color stability while improving luminous flux output.
3Use of energy by moving object
If conventional LED combinations are used to achieve high efficiency, then power efficiency improves, but color rendering fidelity deteriorates
Solution Approach 1:
The patent applies local quality by optimizing the spectral contribution of each LED string according to its specific wavelength region. Each LED type (blue, cyan, yellow-green, red) is tuned to provide appropriate power in its characteristic spectral region, creating a balanced overall spectrum that achieves both high power efficiency and high color rendering fidelity (Rf≥80, Rg≥80) across all operating conditions.
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
This solution enables the generation of white light with high Fidelity Index (Rf) and Gamut Index (Rg) values, ensuring excellent color rendering across a wide range of CCT values from 1800K to 10000K, with COI values less than 3.3 in the 3300K to 5500K range, providing improved color stability and tunability.
Implementation Method 1
The first LED and first luminophoric medium together emit a first unsaturated light... the second LED and second luminophoric medium together emit a second unsaturated light...
Data Source
AI summary
The present disclosure provides systems for generating tunable white light. The systems include a plurality of LED strings that generate light with color points that fall within blue, yellow/green, red, and cyan color ranges, with each LED string being driven with a separately controllable drive current in order to tune the generated light output.