Light-emitting device with orange phosphor spectral tuning
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Solution Overview
Problem
Existing light-emitting devices struggle to efficiently emit white light in the incandescent bulb color range while maintaining high color rendering, as they suffer from mutual light absorption between phosphors, reducing emission efficiency.
Innovation Solution
A semiconductor light-emitting device configuration using a green phosphor with a narrow emission spectrum and an orange phosphor with a broader emission spectrum, where the orange phosphor has a peak wavelength of 590-630 nm and a full width at half maximum (FWHM) of 130 nm or greater, and an absorptance ratio of less than 0.60 at 530 nm, to minimize mutual light absorption and enhance Ra and R9 values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a red phosphor is added to combine with YAG phosphor to achieve warm white light emission, then color rendering index (Ra and R9) is improved, but mutual light absorption between phosphors increases and light emission efficiency decreases
Solution Approach 1:
The patent extracts the problematic red phosphor component from the system and replaces it with an orange phosphor having specific spectral characteristics. This removal of the harmful element (red phosphor that causes mutual absorption) while maintaining the beneficial function (warm white light emission and good color rendering) resolves the contradiction between color rendering and light emission efficiency.
Solution Approach 2:
The patent changes the spectral parameters of the phosphor material by specifying an orange phosphor with peak wavelength of 590-630 nm and FWHM of 80-150 nm, along with controlled absorptance ratio (0.05-0.50) at 530 nm. These parameter changes optimize the phosphor's light absorption and emission characteristics to minimize mutual absorption while maintaining warm white color temperature (2000-3500 K) and high color rendering.
2Loss of energy
If a green phosphor with narrow emission spectrum is used, then mutual light absorption is reduced and light emission efficiency is improved, but color rendering may be compromised
Solution Approach 1:
The patent combines a green phosphor with narrow emission spectrum with an orange phosphor having broader emission spectrum. This merging of two phosphors with complementary spectral characteristics achieves both high light emission efficiency (through minimal mutual absorption) and excellent color rendering (through the orange phosphor's broad spectrum covering 590-630 nm). The combination produces warm white light with color temperature 2000-3500 K and high Ra and R9 values.
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 configuration significantly improves color rendering and light emission efficiency, achieving high Ra and R9 values while effectively emitting white light within the incandescent bulb color range, with the green phosphor's narrow FWHM and orange phosphor's broader FWHM optimizing light absorption and emission.
Implementation Method 1
a green phosphor that absorbs the blue light and emits green light
Implementation Method 2
an orange phosphor that absorbs the blue light and emits orange light
Data Source
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AI summary
Disclosed is a light-emitting device that exhibits good color rendering and highly efficiently emits white light in an incandescent bulb color range. The semiconductor light-emitting device (1) of the present invention includes: a semiconductor light-emitting element (2) that emits blue light; a green phosphor (14) that absorbs the blue light and emits green light; and an orange phosphor (13) that absorbs the blue light and emits orange light. The orange phosphor (13) produces an emission spectrum having a peak at a wavelength of equal to or greater than 590 nm but equal to or less than 630 nm and having a full width at half maximum of 130 nm or greater at the peak, the full width at half maximum of the emission spectrum of the orange phosphor (13) being broader than a full width at half maximum of an emission spectrum of the green phosphor (14). The orange phosphor (13) exhibits an absorptance having a peak wavelength of 420 nm or greater. ABS(530) and ABS(MAX) satisfy a relation, ABS(530)/ABS(MAX) < 0.60, where ABS(MAX) is an absorptance of the orange phosphor (13) at the peak wavelength thereof, and ABS(530) is an absorptance of the orange phosphor (13) at a wavelength of 530 nm.