Light Emitting Device Blue Emission Color Rendering
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Solution Overview
Problem
Conventional light emitting devices have inadequate color rendering properties, particularly in the blue region, leading to low color rendering index values and insufficient emission intensity, which affects the appearance of illuminated objects.
Innovation Solution
A light emitting device incorporating a gallium nitride-based compound semiconductor light emitting element with a peak emission wavelength between 440 nm to 460 nm, combined with a phosphor member containing specific phosphors such as Eu-activated alkaline earth aluminate, Ce-activated rare earth aluminate, Eu-activated silicon nitride, and Mn-activated fluorogermanate, to achieve a continuous emission spectrum from purple to blue, green to yellow, and orange to red, similar to sunlight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphors emitting yellow, green, and red light are employed, then color rendering properties are improved in those regions, but emission intensity in the blue region cannot be brought close to the reference light source
Solution Approach 1:
The patent changes the peak emission wavelength parameter of the light emitting element from conventional values to specifically 440-460 nm, and adjusts phosphor composition parameters (Eu concentration 0.01-0.10 mass%, Cl content 1-20 mass%) to achieve the desired emission spectrum and color rendering properties
Solution Approach 2:
The patent uses a composite phosphor system comprising multiple phosphors (Eu-activated alkaline earth aluminate, Eu-activated silicate with Ca/Mg/Cl, and other phosphors) to achieve continuous emission spectrum from blue to red regions, resolving the contradiction between blue emission intensity and overall color rendering
2Stability of the object's composition
If near ultraviolet light emitting element is employed, then continuous emission spectrum can be achieved, but ultraviolet components adversely affect human body and objects while degrading device components
Solution Approach 1:
The patent shifts the peak emission wavelength parameter from near ultraviolet region to visible blue region (440-460 nm), eliminating harmful UV components while maintaining continuous emission spectrum through careful selection of phosphor materials and their composition ratios
Solution Approach 2:
The patent converts the potentially harmful near-UV radiation into beneficial visible blue light (440-460 nm) that achieves the same continuous spectrum effect without the harmful UV components, protecting both human health and device components
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 rendering properties by improving the blue emission intensity and achieving high color rendering indexes, including an average color rendering index of at least 80 and special color rendering indexes of at least 50, thereby providing a more accurate representation of colors.
Implementation Method 1
a light emitting device in which a blue light emitting LED and a yellow light emitting phosphor are combined. This light emitting device emits white light by combining the blue light from the LED with the yellow light from the phosphor that is excited by the blue light
Implementation Method 2
the yellow light from the phosphor that is excited by the blue light
Data Source
AI summary
A light emitting device, comprising a light emitting element having a peak emission wavelength in a range of from 440 nm to 460 nm, and a phosphor member. The phosphor member contains: a first phosphor having a peak emission wavelength in a range of from 440 nm to 550 nm and comprising at least one selected from the group consisting of an Eu-activated alkaline earth aluminate or an Eu-activated silicate containing Ca, Mg, and Cl; a second phosphor having a peak emission wavelength in a range of from 500 nm to 600 nm and comprising a Ce-activated rare earth aluminate; a third phosphor having a peak emission wavelength in a range of from 610 nm to 650 nm and comprising an Eu-activated silicon nitride containing Al and at least one selected from the group consisting of Sr and Ca; and a fourth phosphor having a peak emission wavelength in a range of from 650 nm to 670 nm and comprising a Mn-activated fluorogermanate.