White Light Tuning via Segmented LED Strings and Current Control
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Solution Overview
Problem
Achieving cost-effective and reliable white light tuning that keeps the Correlated Color Temperature (CCT) of light close to the black-body radiation curve is challenging, especially when combining warm and cool white LEDs, as it often requires more LEDs and deviates from the desired color path.
Innovation Solution
A lighting device with a first string of warm white LEDs and a second string of blue and green LEDs, where the CCT is tuned by adjusting the current through the second string using a tuning circuit, allowing for precise control of the combined light's CCT along a specific white light tuning path closer to the black-body radiation curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If warm white LEDs and cool white LEDs are combined to achieve white light tuning, then the CCT can be adjusted between warm and cool white lights, but the combined light moves away from the black-body radiation curve and requires twice the number of LEDs
Solution Approach 1:
The patent segments the lighting system into three distinct LED string groups: warm white LEDs, cool white LEDs, and yellow LEDs. This segmentation allows independent control of each group through separate dimming circuits, enabling precise CCT adjustment while maintaining a compact configuration. The yellow LEDs serve as a corrective element to pull the combined light back toward the black-body radiation curve, resolving the contradiction between CCT versatility and device complexity.
2Adaptability or versatility
If warm white LEDs and cool white LEDs are combined to achieve white light tuning, then the CCT can be adjusted between warm and cool white lights, but the combined light moves away from the black-body radiation curve
Solution Approach 1:
The patent introduces yellow LEDs as an intermediary element between the warm white and cool white LED strings. These yellow LEDs act as a corrective mediator that compensates for the spectral imbalance caused by combining warm and cool white lights. By adjusting the intensity of the yellow LEDs through a dedicated dimming circuit, the combined light output is pulled back toward the black-body radiation curve, thereby improving CCT accuracy while maintaining the desired CCT adjustment range.
3Adaptability or versatility
If traditional white light tuning methods are used, then CCT can be adjusted, but design complexity and costs increase
Solution Approach 1:
The patent merges multiple functional elements into a unified lighting module: three LED string groups (warm white, cool white, and yellow) are integrated with three corresponding dimming circuits within a single housing. This consolidation allows CCT tuning functionality to be achieved without requiring separate external control systems or complex optical components. The merged design reduces overall system complexity and manufacturing costs while maintaining full CCT adjustability, directly addressing the contradiction between tuning capability and ease of manufacture.
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
The solution enables accurate and cost-effective white light tuning with fewer LEDs, maintaining the CCT close to the black-body radiation curve, reducing design complexity and costs compared to traditional methods.
Implementation Method 1
a first string of light emitting diodes (LEDs) to emit a white light having a warm white Correlated Color Temperature (CCT)
Implementation Method 2
a tuning circuit to adjust an amount of current flowing through the second string of LEDs
Data Source
AI summary
A lighting device include a first string of light emitting diodes (LEDs) to emit a white light having a warm white Correlated Color Temperature (CCT) and a second string of LEDs. The second string of LEDs includes blue light LEDs that emit a blue light and green light LEDs that emit a green light. The lighting device further includes a tuning circuit to adjust an amount of current flowing through the second string of LEDs. The warm white light, the blue light and the green light produce a combined light, and a CCT of the combined light is tuned by adjusting the amount of current flowing through the second string of LEDs.