LED Light Sources Using LAG and Red Phosphors for Color Preference
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Solution Overview
Problem
Current color quality metrics, such as the Color Rendering Index (CRI), are inadequate in evaluating and reflecting the quality of LED light sources, particularly in terms of consumer preference for enhanced color preference, as they fail to accurately quantify the perceived color saturation and whiteness, leading to suboptimal design optimization for light sources.
Innovation Solution
The development of a Lighting Preference Index (LPI) metric, which combines Whiteness and Color Appearance to optimize the spectral power distribution of light sources, utilizing a composite light source comprising blue LEDs, LAG phosphors, and narrow or broad red phosphors to achieve enhanced color preference, with specific peak wavelengths and full-width at half-maximum (FWHM) ranges, to maximize LPI values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color quality metrics like CRI are used to evaluate LED light sources, then the evaluation process is simple and established, but the metrics fail to accurately reflect consumer preference and perceived color quality
Solution Approach 1:
The patent introduces a new evaluation parameter (Lighting Preference Index or LPI) that combines multiple spectral characteristics (color rendering, color saturation, whiteness) into a single comprehensive metric. This parameter change enables more accurate prediction of consumer preference while maintaining practical evaluability through standardized measurement procedures.
Solution Approach 2:
The LPI metric acts as a composite evaluation tool that integrates multiple spectral performance aspects (color rendering index, color saturation, whiteness perception) into one unified measure. This composite approach provides both accuracy in reflecting consumer preference and simplicity in application, resolving the contradiction between measurement precision and ease of use.
2Ease of manufacture
If LED light sources use standard phosphor combinations, then manufacturing is simple and cost-effective, but color preference and perceived quality are suboptimal
Solution Approach 1:
The patent applies local quality by optimizing specific spectral regions (enhancing red and green wavelengths, suppressing yellow) rather than uniformly adjusting the entire spectrum. This allows standard phosphor materials to be used while achieving enhanced color preference through targeted spectral modifications in critical wavelength regions.
Solution Approach 2:
The invention changes key spectral parameters (peak wavelengths, full width at half maximum, relative intensities) of phosphor emissions to achieve enhanced color preference. By adjusting these parameters within the capabilities of standard phosphor materials, the patent maintains manufacturing simplicity while achieving superior color quality.
3Manufacturing precision
If yellow light is suppressed to enhance color contrast, then red-green color preference is improved, but overall luminous efficiency may decrease
Solution Approach 1:
The patent applies local quality by selectively modifying only the yellow region of the spectrum while preserving emissions in other critical regions (blue, green, red). This targeted approach enhances red-green color contrast without unnecessarily suppressing other wavelengths that contribute to luminous efficiency, thus resolving the contradiction between color preference and energy utilization.
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 LPI metric enables the design of light sources with significantly higher color preference compared to existing products, achieving enhanced color contrast and whiteness, thereby improving the perceived color quality and user preference.
Implementation Method 1
at least one green or yellow-green garnet (LAG) phosphor
Implementation Method 2
at least one narrow red down-converter
Data Source
AI summary
According to some embodiments, a composite light source includes at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm; at least one LAG phosphor; at least one narrow red down-converter; and wherein the composite light source has a Lighting Preference Index (LPI) of at least 120. Numerous other aspects are provided.