White Light Tuning via Analog Circuit Correction
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Solution Overview
Problem
Existing white light tuning systems face challenges in achieving cost-effective and reliable color adjustment while keeping the combined white light close to the black-body radiation curve, often resulting in undesirably high Duv values and increased complexity.
Innovation Solution
A low-cost analog circuit that corrects the departure from the black-body radiation curve using a second-order polynomial relationship between the flux ratio of two LEDs, incorporating green and amber lights to adjust the chromaticity, allowing tracking of the black-body curve between any two Correlated Color Temperatures (CCTs) without light sensing or feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a combination of warm white light and cool white light is used for white light color tuning, then the combined light achieves a resultant CCT that is a combination of the warm and cool white lights, but the chromaticity of the resultant white light moves away from the black-body radiation curve as the combined CCT changes
Solution Approach 1:
The patent introduces green light LEDs and amber light LEDs as localized corrections to specific regions of the spectrum. The green light addresses the blue deficiency that causes deviation from the black-body curve, while amber light compensates for the red deficiency. This local quality adjustment allows the overall white light to maintain chromaticity closer to the black-body radiation curve during color tuning.
Solution Approach 2:
The patent combines multiple light sources with different spectral characteristics (warm white LEDs, cool white LEDs, green light LEDs, and amber light LEDs) to create a composite lighting system. This composite approach allows the system to achieve accurate chromaticity control across a wide range of CCT values by synergistically combining the spectral contributions of each light source type.
2Manufacturing precision
If green light LEDs and amber light LEDs are added to correct chromaticity deviation, then the chromaticity of combined white light stays close to the black-body radiation curve, but the device complexity and cost increase
Solution Approach 1:
The patent merges the control of green light and amber light with the existing control architecture for warm and cool white LEDs. By integrating these correction lights into the same control system, the patent reduces overall device complexity compared to implementing separate control circuits for each light source.
Solution Approach 2:
The patent uses parameter changes in the flux ratios of the different light sources to achieve chromaticity correction. By dynamically adjusting the intensity parameters of green and amber lights based on the operational state (warm vs. cool white LED dominance), the system maintains accurate chromaticity without requiring complex mechanical or structural modifications.
3Manufacturing precision
If the flux of green light and amber light is controlled based on flux ratio equations, then accurate white light tuning close to the black-body radiation curve is achieved, but the control system complexity increases
Solution Approach 1:
The control system uses feedback from the operational state (which white LED is dominant and by how much) to automatically determine the required flux ratios for green and amber lights. This self-service approach allows the system to maintain accurate chromaticity control without requiring external calibration or complex manual adjustment mechanisms.
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 accurate white light tuning that closely follows the black-body radiation curve, reducing complexity and cost by using a simple analog circuit to adjust the flux of green and amber lights based on the current through warm and cool white LEDs.
Implementation Method 1
a first string of light emitting diodes (LEDs) configured to emit a warm white light having a warm Correlated Color Temperature (CCT)
Implementation Method 2
keeping the curve of the combined white light relatively close to the black-body radiation curve
Data Source
AI summary
A lighting device includes a first string of light emitting diodes (LEDs) configured to emit a warm white light having a warm Correlated Color Temperature (CCT). The lighting device further includes a second string of LEDs configured to emit a cool white light having a cool CCT. The lighting device also includes green light LEDs that emit a green light. A flux of the green light is controlled based on a flux of the cool white light or a flux of the warm white light. The flux of the warm white light and the flux of the cool white light change proportionally with respect to each other.