Multi-Channel LED Driver CCT Tuning
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Solution Overview
Problem
Existing lighting solutions struggle to maintain a consistent lumen output while adjusting the Correlated Color Temperature (CCT) of light, as the intensity of combined light changes when shifting between warm and cool white LEDs due to differences in their efficiencies.
Innovation Solution
A lighting system with a driver that controls three strings of LEDs, each emitting a different white light with adjustable currents, allowing for independent adjustment of CCT while maintaining a constant sum of currents to compensate for efficiency differences and keep the lumen output consistent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If current is shifted between cool light LEDs and warm light LEDs to adjust CCT, then the CCT of output light can be adjusted, but the intensity of combined light changes undesirably due to efficiency differences
Solution Approach 1:
The system changes the parameters of the lighting system by using three different CCT values (first, second, and third CCT) instead of traditional two-CCT systems. The controller adjusts the ratio of currents to these three LED strings based on the desired output CCT, enabling the output light to follow the black-body curve more accurately while maintaining constant lumen output through proportional current adjustment
Solution Approach 2:
The system dynamically adjusts the current distribution to the three LED strings in real-time based on the desired CCT setting. The controller continuously modifies the current ratios to maintain both the black-body curve alignment and constant lumen output, making the system adaptive rather than fixed
2Temperature
If only two strings of LEDs with different CCTs are used, then device complexity is reduced, but the ability to maintain constant lumen output while adjusting CCT follows the black-body curve is limited
Solution Approach 1:
The system transitions from a two-dimensional CCT adjustment space (two LED strings) to a three-dimensional space (three LED strings with different CCTs). This additional dimension enables the system to achieve both black-body curve alignment and constant lumen output simultaneously, as the extra degree of freedom allows for more flexible current ratio optimization
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 system effectively maintains a consistent lumen output and keeps the CCT close to the black-body curve by proportionally adjusting the currents to the LEDs, ensuring the lighting remains constant in intensity across various CCT settings.
Implementation Method 1
a first string of light emitting diodes (LEDs) that emit a first white light having a first CCT
Implementation Method 2
light emitting diodes (LEDs) that emit a first white light
Data Source
AI summary
A driver of a lighting fixture includes a power circuitry configured to provide a first current to a first string of light emitting diodes (LEDs), a second current to a second string of LEDs, and a third current to a third string of LEDs that emit a third white light. The driver further includes a controller that controls the power circuitry to change an amount of the first current, an amount of the second current, and an amount of the third current to adjust a CCT of an output light provided by a lighting fixture. The output light includes two white lights from among the first white light, the second white light, and the third white light, where the first current, the second current, and the third current are adjustable independent of each other.