LED Segment Selection Circuit for Targeted Spectral Power Distribution
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Solution Overview
Problem
Solid state lighting systems face challenges in achieving consistent color reproduction and dimming performance due to variations in LED manufacturing, which affect the color temperature and rendering index of the light output, making it difficult to mimic the warm color behavior of incandescent lighting.
Innovation Solution
A dimmable solid state lighting apparatus with multiple LED segments, each having a targeted spectral power distribution, is configured to selectively control current through the segments using an LED segment selection circuit, shifting the light output to achieve a desired color temperature and rendering index, similar to incandescent lighting, by adjusting the power distribution based on dimming input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple LED segments with different spectral power distributions are used, then color rendering and correlated color temperature control are improved, but device complexity increases
Solution Approach 1:
The lighting apparatus is divided into multiple LED segments, where each segment contains LEDs with specific spectral power distributions tailored to emit light at different correlated color temperatures. This segmentation allows independent control of each segment's spectral characteristics, enabling precise control over the overall color rendering and correlated color temperature of the combined light output.
Solution Approach 2:
Different LED segments are assigned different spectral power distributions and correlated color temperature characteristics based on their local function within the overall lighting system. Each segment is optimized with specific photometric and colorimetric properties to contribute differently to the total light output, allowing targeted spectral control at different spatial or functional locations within the apparatus.
2Adaptability or versatility
If LED segments are selectively controlled to shift light output, then color behavior approximation to incandescent lighting is improved, but control circuit complexity increases
Solution Approach 1:
The control circuit dynamically adjusts the operation of different LED segments based on dimming input signals, enabling the lighting apparatus to adapt its spectral power distribution and correlated color temperature in real-time. This dynamic control allows the system to shift between different color temperatures and spectral characteristics, approximating the continuous color behavior change characteristic of incandescent lighting during dimming operations.
Solution Approach 2:
The control circuit manipulates operational parameters such as current levels and segment activation states to change the spectral power distribution and correlated color temperature of the combined light output. By varying these parameters in response to dimming inputs, the system achieves adaptive color behavior that mimics incandescent lighting across different brightness levels.
3Ease of operation
If current through LED segments is adjusted for dimming, then dimming performance is improved, but manufacturing variations affect spectral consistency
Solution Approach 1:
The system incorporates feedback mechanisms that monitor the actual light output characteristics of each LED segment and adjust control signals accordingly. This feedback loop compensates for manufacturing variations in LED segments, ensuring that the combined spectral power distribution and correlated color temperature remain consistent across different dimming levels despite inherent variations in individual LED components.
Solution Approach 2:
The control circuit adjusts operational parameters such as forward current and pulse width modulation duty cycles for each LED segment to compensate for manufacturing variations. By dynamically changing these parameters, the system maintains consistent spectral power distribution and correlated color temperature characteristics across the full dimming range, overcoming the effects of component tolerances and manufacturing spread.
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 allows for a more accurate and pleasing color reproduction, closely approximating incandescent lighting behavior by adjusting the spectral power distribution during dimming, enhancing the lighting characteristics such as color quality and efficacy.
Implementation Method 1
A solid state light emitting device may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs)
Implementation Method 2
phosphor converted LEDs
Data Source
AI summary
A dimmable solid state lighting apparatus can include a plurality of light emitting diode (LED) segments including a first LED segment that can have a targeted spectral power distribution for light emitted from the apparatus that is different than spectral power distributions for other LED segments included in the plurality of LED segments. An LED segment selection circuit can be configured to selectively control current through the plurality of LED segments to shift the light emitted by the apparatus to the targeted spectral power distribution responsive to dimming input.