Light-emitting device with red LED for natural color appearance
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Solution Overview
Problem
Current light-emitting devices prioritize efficiency and power saving over color appearance, leading to unnatural and uncomfortable illumination, especially in indoor environments with low illuminance, where colors appear dull and hues deviate from their natural appearance.
Innovation Solution
An illumination method and light-emitting device that utilize semiconductor light-emitting elements and phosphors to achieve a specific spectral power distribution, ensuring a color appearance that is natural, vivid, and comfortable by controlling the distance from the black-body radiation locus, saturation differences, and hue angles, even at low illuminance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light-emitting devices use semiconductor light-emitting elements and phosphors to achieve higher efficiency and power saving, then energy efficiency is improved, but color appearance becomes unnatural and colors appear dull
Solution Approach 1:
The patent applies local quality by adding a red light-emitting element specifically positioned to supplement the red region (610-780 nm) of the spectrum. This localized spectral enhancement targets only the deficient wavelength range while maintaining the efficient blue LED excitation and yellow phosphor conversion for other regions, thereby improving color appearance without compromising overall energy efficiency.
Solution Approach 2:
The patent employs composite materials by combining a blue semiconductor light-emitting element (430-480 nm peak wavelength) with a yellow phosphor material and a red semiconductor light-emitting element (610-780 nm peak wavelength). This composite light source structure integrates different emission mechanisms (LED electroluminescence and phosphor photoluminescence) to create a spectrum that maintains high efficiency while achieving natural color appearance.
2Loss of energy
If light-emitting devices optimize for efficiency with blue LED and yellow phosphor combination, then power consumption is reduced, but color rendering index and color accuracy deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the spectral power distribution parameters, specifically ensuring the red region (610-780 nm) contributes 15-40% of total luminous flux. This parameter adjustment transforms the conventional blue LED+yellow phosphor spectrum into an optimized spectrum that maintains low power consumption while achieving Ra≥90 and R9≥90 color rendering metrics.
3Loss of energy
If indoor illuminance is reduced for energy saving, then energy consumption decreases, but color appearance becomes dull and details become less legible
Solution Approach 1:
The patent applies local quality by strategically enhancing the red spectral region (610-780 nm) which is critical for color perception and visual comfort. This localized spectral enhancement allows the light source to maintain vivid color appearance and detail legibility at lower overall illuminance levels, thereby reducing energy consumption without sacrificing visual quality.
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 method and device provide a color appearance that is as natural and vivid as outdoor high-illuminance environments, making colors appear more accurate and comfortable, with white appearing whiter and details being more legible, even at indoor illuminance levels of around 5000 lx or lower.
Implementation Method 1
light emitted from a light-emitting device including a semiconductor light-emitting element that is a light-emitting element
Implementation Method 2
utilize semiconductor light-emitting elements and phosphors to achieve a specific spectral power distribution
Data Source
AI summary
To provide an illumination method and a light-emitting device which are capable of achieving, under an indoor illumination environment where illuminance is around 5000 lx or lower when performing detailed work and generally around 1500 lx or lower, 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. 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.