Adjustable White Light Illumination Devices Using Photo-luminescent Materials
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Solution Overview
Problem
Conventional LED lighting devices emit fixed color correlated temperature (CCT) white light, which cannot adapt to changing circadian rhythms, necessitating a solution for adjustable CCT values in lighting fixtures.
Innovation Solution
An LED illumination device comprising multiple LEDs with tunable CCT values, including red, warm white, and cool white LEDs, along with photo-luminescent materials and a waveguide, allows for adjustable CCT by varying the amplitude and duty cycle of the applied current or voltage, and using reflectors for collimation and reduced crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional phosphor-converted LEDs are used to generate white light, then the device structure is simple and manufacturing is easy, but the CCT value is fixed and cannot be adjusted
Solution Approach 1:
The invention segments the white light generation into multiple independent LED types (red LEDs, warm white LEDs, cool white LEDs) that can be individually controlled. Each LED type contributes differently to the final spectrum, allowing independent adjustment of their drive currents to achieve variable CCT values while maintaining overall system functionality.
Solution Approach 2:
The invention implements dynamic control of CCT by varying the drive currents to different LED groups in real-time. The control circuitry adjusts the relative intensities of red, warm white, and cool white LEDs dynamically, enabling the CCT to change continuously across a wide range (1800K-6500K) to match circadian rhythms.
2Adaptability or versatility
If multiple LED types are combined to achieve tunable CCT, then the CCT adaptability improves, but the device complexity and control difficulty increase
Solution Approach 1:
The invention incorporates feedback mechanisms where the control circuitry monitors the combined light output from multiple LED groups and adjusts drive currents accordingly. This feedback loop ensures accurate CCT control and compensates for variations in LED characteristics, simplifying operation while maintaining wide CCT adjustability.
Solution Approach 2:
The control circuitry is designed to universally manage multiple LED types through a single interface. The system can operate in different modes (fixed CCT, dynamic circadian tracking, manual adjustment) and the same control architecture handles all LED groups, reducing operational complexity despite the multi-LED configuration.
3Adaptability or versatility
If photo-luminescent materials are used for light conversion, then the CCT tuning capability is enhanced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts the light conversion function from complex phosphor coatings and replaces it with direct emission from multiple LED types. By eliminating the need for phosphor materials and their associated deposition processes, the system achieves spectrum tunability through electrical control of multiple LED groups, significantly simplifying manufacturing while maintaining CCT adjustability.
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
Enables the generation of white light with target CCT values, accommodating human circadian rhythms by adjusting the color temperature dynamically, enhancing lighting adaptability and user comfort.
Implementation Method 1
one or more photo-luminescent materials (e.g., a phosphor, a quantum dot material and/or a fluorescent dye) for shifting (i) the CCT value of the light emitted from the cool white LED(s) toward a green CCT value and/or (ii) the CCT value of the light emitted from the warm white LED(s) toward a yellow CCT value
Implementation Method 2
a waveguide material having (i) a mixing region for mixing the shifted and unshifted light so as to generate white light having the target CCT value and (ii) an output region for outputting the white light
Implementation Method 3
each LED may be disposed within a 'cup-shaped' (e.g., parabolic) reflector for reducing 'crosstalk' interactions between the light emitted from an LED and the photo-luminescent material(s) disposed above a neighboring LED. In addition, the reflector may be made of a high-reflectivity material so as to redirect upward light from the respective LED, thereby achieving at least partial collimation of the beam.
Data Source
AI summary
A lighting device producing white light having a target color correlated temperature (CCT) value includes an LED array having one or more red LEDs, one or more warm white LEDs, and one or more cool white LED; one or more photo-luminescent materials for shifting the CCT value of the light emitted from the cool white LED toward a green CCT value and/or the CCT value of the light emitted from the warm white LED toward a yellow CCT value; and a waveguide material having a mixing region for mixing the shifted and unshifted light so as to generate white light having the target CCT value and an output region for outputting the white light.