Light-Emitting Device Spectral Control for Low Illuminance Color Appearance
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Solution Overview
Problem
Current light-emitting devices do not adequately consider color appearance and visibility, especially in low illuminance environments, as high color rendering indices do not necessarily lead to favorable color perception, and the Hunt effect causes colors to appear dull when illuminance decreases.
Innovation Solution
A light-emitting device and method that adjusts the spectral power distribution to maintain a distance from the black-body radiation locus and optimize saturation and hue differences for 15 Munsell renotation color samples, ensuring improved color appearance and visibility in illuminance ranges of 5 lx to 150 lx.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light-emitting devices are designed to achieve higher luminous efficacy and efficiency, then energy consumption is reduced and luminous output is improved, but color appearance and visibility when illuminating objects deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the spectral power distribution parameters of the light-emitting device. Specifically, it sets the distance from the black-body radiation locus (Duv) within -0.04268 to -0.0070 and regulates saturation differences (ΔCn) and hue angle differences (Δhn) for 15 Munsell color samples. These parameter optimizations enable the device to achieve high luminous efficacy while maintaining excellent color appearance and visibility, particularly in low illuminance conditions of 5-150 lx.
2Measurement precision
If the spectral power distribution is adjusted to improve color rendering index scores, then CRI metrics are enhanced, but actual color perception and visibility do not necessarily improve
Solution Approach 1:
The patent applies local quality by making targeted spectral adjustments in specific wavelength regions rather than uniformly optimizing across the entire spectrum. It specifically enhances the spectral power distribution in regions critical for color perception while maintaining efficiency, using multiple phosphors with different emission characteristics to create localized spectral enhancements that improve both CRI scores and actual color perception.
Solution Approach 2:
The patent transforms the abstract CRI measurement concept into tangible color perception improvements by controlling specific spectral parameters. It sets Duv within -0.04268 to -0.0070 and optimizes saturation differences (ΔCn) and hue angle differences (Δhn) for 15 Munsell color samples, ensuring that spectral adjustments translate into real-world color appearance benefits rather than merely improving test scores.
3Use of energy by moving object
If illuminance is reduced to save energy, then power consumption decreases, but color saturation and visibility deteriorate due to the Hunt effect
Solution Approach 1:
The patent applies parameter changes by optimizing the spectral power distribution to maintain color saturation at low illuminance levels. It controls the distance from the black-body radiation locus (Duv) within -0.04268 to -0.0070 and regulates saturation differences (ΔCn) for 15 Munsell color samples, enabling the light-emitting device to overcome the Hunt effect and maintain vivid color appearance even when illuminance is reduced to energy-saving levels of 5-150 lx.
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 enhances color appearance and visibility of chromatic colors and skin tones, providing a more favorable perception compared to conventional light sources at similar illuminance levels, even in low light conditions.
Implementation Method 1
light emitted from a light-emitting device illuminates an object
Implementation Method 2
a distance DuvSSL from a black-body radiation locus as defined by ANSI C78.377
Data Source
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AI summary
An object of the present invention is to provide an illumination method with which improvements in the appearance of colors perceived by a human at an illuminance of 5 lx to 150 lx are achieved in terms of visibility, the color appearance of chromatic colors perceived by a human, and a feeling of brightness, a color appearance or an object appearance as perceived by a person, will be as natural, vivid, highly visible, and comfortable as though perceived outdoors in a high-illuminance environment, regardless of scores of various color rendition metric, as well as a light-emitting device for implementing the illumination method. Light emitted from the light-emitting device illuminates an object such that light measured at a position of the object satisfies specific requirements. A feature of the light-emitting device is that light emitted by the light-emitting device in a main radiant direction satisfies specific requirements.