Tunable White Light via Multi-Channel LED Control
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Solution Overview
Problem
Current LED lamps face challenges in providing white light across a range of correlated color temperatures (CCT) values while maintaining high efficiency, luminous flux, good color rendering, and color stability, as well as controlling circadian energy performance, particularly due to the limitations of existing LED technologies in achieving desirable lighting performance and circadian stimulus.
Innovation Solution
The use of semiconductor light emitting devices comprising 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 with high color rendering indices and circadian performance, by emitting lights within defined color ranges on the 1931 CIE Chromaticity Diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LEDs with different peak wavelengths are used to generate white light, then the correlated color temperature range is expanded, but the color rendering index deteriorates due to gaps in spectral power distribution
Solution Approach 1:
The patent divides the white light generation into multiple independent LED channels (e.g., blue LED at 450nm, cyan LED at 495nm, green LED at 530nm, yellow LED at 560nm, red LED at 630nm), each with its own luminescent material. This segmentation allows independent control of each wavelength component to fill spectral gaps while maintaining continuous spectrum for high CRI.
Solution Approach 2:
The patent employs composite luminescent materials including phosphors and quantum dots with specific emission characteristics. These composite materials are selected and combined to provide broad spectral coverage with peak wavelengths strategically positioned to eliminate gaps, achieving both wide CCT range and high CRI simultaneously.
2Productivity
If LED drive currents are increased to improve luminous flux, then the light output intensity is improved, but the color stability deteriorates
Solution Approach 1:
The patent implements dynamic control of drive currents to each LED channel through separate control circuits. This allows real-time adjustment of current ratios between different wavelength LEDs to compensate for nonlinear luminous flux responses and maintain stable color coordinates across varying total luminous flux levels.
Solution Approach 2:
The patent incorporates feedback mechanisms where the actual color output is monitored and used to adjust drive currents to each LED channel. This closed-loop control ensures color stability is maintained even as total luminous flux changes, by dynamically rebalancing the spectral composition.
3Adaptability or versatility
If LED lamps are designed to provide tunable white light across CCT range, then the adaptability to different lighting conditions is improved, but the device complexity increases
Solution Approach 1:
The patent designs the control circuit to perform multiple functions simultaneously: individual channel current control, total luminous flux regulation, color temperature tuning, and CRI optimization. This multi-functionality reduces the need for separate dedicated circuits for each function, managing complexity while achieving comprehensive control.
Solution Approach 2:
The patent combines the control of multiple LED channels and luminescent materials into a unified control architecture that manages all wavelength components through integrated control logic. This merging approach simplifies the overall system by coordinating all elements through a single control framework rather than independent control systems.
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 color rendering indices and circadian performance, allowing for tunable lighting that meets a range of CCT values, improving both visual and circadian effectiveness.
Implementation Method 1
semiconductor light emitting devices comprising multiple LED strings with different luminescent materials
Implementation Method 2
LED strings with different luminescent materials and a drive circuit that adjusts the relative drive currents to combine unsaturated lights
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. The methods include using a plurality of LED strings to generate light with color points that fall within white, 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.