Phosphor-Converted White LEDs With Partial Conversion
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Solution Overview
Problem
Current phosphor-conversion (PC) LEDs rely on outdated color rendering assessment procedures that use a limited number of test samples, failing to accurately capture the color rendering capabilities of white light sources, which are essential for achieving high color quality and rendering a wide range of spectrophotometrically calibrated colors.
Innovation Solution
The development of new 3-4 component combinations of peak wavelengths and bandwidths for white PC LEDs that utilize blue electroluminescent LEDs and wide-band or narrow-band phosphors to generate spectral power distributions that closely mimic blackbody radiators or daylight illuminants, using a larger set of spectrophotometrically calibrated colors and advanced chromatic adaptation methods to preserve chromaticity and lightness shifts across a broader range of colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard CIE 1995 color rendering assessment procedures with limited test samples are used, then the assessment process is simple and quick, but the color rendering capability cannot be accurately captured and color quality is compromised
Solution Approach 1:
The patent changes the parameters of color rendering assessment by introducing a new metric (number of rendered colors Nr) that evaluates the entire visible spectrum rather than relying on limited test samples. This parameter change enables accurate capture of color rendering capability while maintaining practical assessability through computational methods.
Solution Approach 2:
The patent transitions from traditional 2D chromaticity diagram assessment to a 3D spectral power distribution analysis. By evaluating spectral characteristics across wavelength, chromaticity, and luminance dimensions simultaneously, the invention achieves comprehensive color rendering assessment that captures the full complexity of human color perception.
2Use of energy by moving object
If blue LED with phosphor conversion is used to create white light, then energy efficiency is improved compared to traditional sources, but the number of renderable colors is limited
Solution Approach 1:
The patent employs composite phosphor systems combining multiple phosphor materials with different emission characteristics. This composite approach broadens the spectral power distribution while maintaining the energy efficiency of LED excitation, enabling rendering of a high number of colors through synergistic phosphor combinations.
Solution Approach 2:
The patent segments the white light generation into distinct spectral components from multiple phosphors, each contributing specific wavelength ranges. This segmentation allows precise control over the spectral power distribution to cover a broad color gamut while maintaining overall energy efficiency through the blue LED pump source.
3Measurement precision
If spectral power distribution is optimized for maximum color rendering, then color fidelity is improved, but luminous efficacy may be reduced
Solution Approach 1:
The patent applies partial conversion in phosphors rather than complete conversion, allowing the blue LED component to remain visible and contribute to luminous efficacy. This partial action approach balances color fidelity improvement through phosphor conversion while preserving energy efficiency by not fully converting the blue spectrum.
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
This approach enables the creation of white light sources that render a high number of colors indistinguishably from a blackbody radiator or daylight illuminant, achieving superior color rendering indices and luminous efficacy, surpassing traditional PC LEDs in terms of color fidelity and energy conversion efficiency.
Implementation Method 1
phosphors that partially absorb and convert the flux generated by the LEDs to light with other wavelengths
Implementation Method 2
blue electroluminescent light-emitting diodes (LEDs)
Data Source
AI summary
The invention relates to phosphor-conversion (PC) sources of white light, which are composed of at least two groups of emitters, such as blue electroluminescent light-emitting diodes (LEDs) and wide-band (WB) or narrow-band (NB) phosphors that partially absorb and convert the flux generated by the LEDs to other wavelengths, and to improving the quality of the white light emitted by such light sources. In particular, embodiments of the present invention describe new 3-4 component combinations of peak wavelengths and bandwidths for white PC LEDs with partial conversion. These combinations are used to provide spectral power distributions that enable lighting with a considerable portion of a high number of spectrophotometrically calibrated colors rendered almost indistinguishably from a blackbody radiator or daylight illuminant, and which differ from distributions optimized using standard color-rendering assessment procedures based on a small number of test samples.