Tunable White Light LED Strings for Circadian Control
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Solution Overview
Problem
Current LED lamps face challenges in providing white light with tunable circadian energy performance across a range of correlated color temperatures (CCT) while maintaining high efficiency, luminous flux, and good color rendering, particularly in achieving desirable lighting performance that controls circadian rhythms without disrupting natural biological processes.
Innovation Solution
The method involves using LED strings with different peak wavelengths, such as blue, red, yellow/green, and cyan LEDs, combined with luminophoric mediums to produce white light that can be tuned across various CCT values, ensuring high color rendering indices and circadian action factor values, by varying the drive currents to achieve specific color coordinates within a 7-step MacAdam ellipse on the 1931 CIE Chromaticity Diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs with different peak wavelengths are combined to produce white light, then color rendering is improved, but spectral gaps remain in regions remote from peak wavelengths
Solution Approach 1:
The patent combines multiple LEDs with different peak wavelengths (blue, cyan, yellow/green, red) to produce white light with improved color rendering. By merging these different wavelength sources, the patent achieves broader spectral coverage while maintaining the benefits of LED efficiency.
2Adaptability or versatility
If LED drive currents are adjusted to tune CCT, then circadian energy performance is improved, but maintaining high efficiency and luminous flux across broad CCT range becomes difficult
Solution Approach 1:
The patent dynamically adjusts the drive currents to different LED types (blue, cyan, yellow/green, red) to achieve tunable correlated color temperature (CCT) across a broad range. This dynamic current control enables the system to optimize circadian energy performance while maintaining energy efficiency by selectively energizing appropriate LED combinations for different CCT targets.
Solution Approach 2:
The patent changes the electrical parameters (drive currents) of multiple LED types to achieve desired CCT values and circadian action factor values. By varying current parameters across different LED channels, the system maintains high efficiency and luminous flux while achieving broad CCT tuning capability.
3Ease of manufacture
If conventional LED lamps are used, then manufacturing simplicity is maintained, but control over circadian rhythms and biological processes is insufficient
Solution Approach 1:
The patent creates a multi-functional LED lamp that not only provides illumination but also controls circadian rhythms and biological processes. By integrating multiple LED types with different spectral characteristics into a single device, the patent achieves both general lighting and circadian regulation functions, enhancing versatility while maintaining manufacturing feasibility.
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 approach allows for the generation of white light with improved color rendering and circadian performance, enabling flexible CCT tuning and maintaining high efficiency across a broad range of CCT values, thereby addressing the limitations of existing LED technologies in lighting applications.
Implementation Method 1
semiconductor light emitting devices such as light emitting diodes (LEDs)
Implementation Method 2
Most LEDs are substantially monochromatic light sources that appear to emit light having a single color
Implementation Method 3
White light may also be produced by utilizing one or more luminescent materials such as phosphors to convert some of the light emitted by one or more LEDs to light of one or more other colors
Data Source
AI summary
The present disclosure provides methods for generating tunable white light with controllable circadian energy performance. The methods use a plurality of LED strings to 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. Different light emitting modes can be selected that utilize different combinations of the plurality of LED strings in order to tune the generated white light.