Tunable White LED Lighting Systems with Segmented Strings
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Solution Overview
Problem
Existing LED lamps face challenges in providing white light across a range of correlated color temperatures (CCT) while maintaining high efficiency, luminous flux, good color rendering, and color stability, as well as controlling circadian energy performance, particularly due to limitations in spectral profiles affecting circadian physiology and health.
Innovation Solution
The use of semiconductor light emitting devices comprising multiple LED strings with associated luminophoric mediums, configured to produce unsaturated color points within specific regions of the 1931 CIE Chromaticity diagram, allowing for adjustable color points within a 7-step MacAdam ellipse across a broad CCT range, and optionally incorporating additional LED strings for enhanced color rendering and circadian performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LED strings with different color temperatures are combined to achieve tunable white light across a broad CCT range, then adaptability is improved, but device complexity increases
Solution Approach 1:
The lighting device is divided into multiple independent LED strings, each containing LEDs with specific peak wavelengths (e.g., 450nm blue, 530nm green, 630nm red) and associated luminophoric mediums. Each string can be independently controlled to achieve different color temperatures and color rendering indices, enabling tunable white light across a broad CCT range while maintaining manageable complexity through modular design
Solution Approach 2:
The LED strings are designed to serve multiple functions simultaneously: generating light at specific wavelengths, converting wavelengths through luminophoric mediums, achieving high color rendering indices (Rf≥90, Rg≥90), and providing circadian regulation. This multi-functionality reduces the need for separate components and simplifies the overall device structure while maintaining adaptability
2Reliability
If LED strings with high color rendering indices are used to improve color rendering performance, then color rendering is improved, but blue light hazard increases
Solution Approach 1:
Different LED strings are assigned specific wavelength characteristics tailored to their functions: some strings use 450nm blue LEDs with luminophoric mediums to generate high color rendering, while other strings use 530nm green and 630nm red LEDs to provide spectral balance and reduce blue light content. This localized optimization of wavelength distribution allows high color rendering (Rf≥90, Rg≥90) while controlling blue light hazard through spatial and spectral separation of functions
Solution Approach 2:
The system dynamically adjusts the intensity and wavelength distribution of light from different LED strings to maintain high color rendering indices while varying the correlated color temperature. By changing the relative contributions of blue, green, and red LED strings, the system can achieve Rf≥90 and Rg≥90 across different CCT ranges while minimizing blue light hazard, particularly in the 1800K-10000K CCT range
3Reliability
If multiple LED strings are used to achieve high color rendering and circadian efficacy, then circadian efficacy is improved, but energy consumption increases
Solution Approach 1:
The control system dynamically adjusts the intensity and wavelength distribution of light from different LED strings based on temporal patterns and user needs. By periodically varying the contribution of circadian-regulating wavelengths (particularly blue and green) versus visual illumination wavelengths, the system maintains high circadian efficacy while reducing overall energy consumption during periods when full circadian stimulation is not required
Solution Approach 2:
The system provides full circadian efficacy and high color rendering only when needed, while allowing partial operation of certain LED strings during other periods. For example, during daytime hours, all LED strings operate to provide both visual illumination and circadian regulation, while during nighttime hours, only necessary illumination is provided with reduced circadian stimulation, thereby reducing energy consumption while maintaining required performance levels
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
These devices generate white light with high color rendering indices (Rf, Rg, Ra) and improved circadian efficacy, while minimizing blue light hazards, enabling tunable white light with desirable lighting performance and health benefits.
Implementation Method 1
a first light emitting diode string... a second light emitting diode string... a third light emitting diode string... a fourth light emitting diode string
Implementation Method 2
Each LED string can have a recipient luminophoric medium
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 red, blue, and green color ranges, with each LED string being driven with a separately controllable drive current in order to tune the generated light output. The systems can include an additional LED string configured for functional applications that includes a type of LED selected from 380-420 nm violet saturated LEDs, 200-280 nm UVC saturated LEDs, 850-940 nm near-IR saturated LEDs, 580-620 nm amber-orange/red saturated LEDs, and 460-490 nm long-blue saturated LEDs.