Light Emitting Device With Composite Fluorescent Materials
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Solution Overview
Problem
Conventional light emitting devices using LEDs and fluorescent materials often struggle to achieve sufficient radiation intensity in the blue-green and red regions, leading to suboptimal color rendering indices, especially when trying to match reference light sources for various applications like medical or museum lighting.
Innovation Solution
A light emitting device comprising a blue LED light emitting element and a combination of fluorescent materials, including Eu-activated alkaline earth aluminate, Mn-activated fluorogermanate, Ce-activated rare earth aluminate, and Eu-activated silicon nitride with Sr and Ca, carefully tuned in content ratios to achieve a correlated color temperature within specific ranges, enhancing color rendering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fluorescent materials (chlorosilicate and garnet phosphor) are used to enhance color rendering, then the general color rendering index is improved, but the radiation intensity in the blue-green and red regions remains insufficient
Solution Approach 1:
The patent combines four different fluorescent materials (Eu-activated alkaline earth aluminate, Mn-activated fluorogermanate, Ce-activated rare earth aluminate, and Eu-activated silicon nitride) to create a composite fluorescent layer. This composite structure allows simultaneous enhancement of color rendering across multiple spectral regions including blue-green and red, while maintaining high radiation intensity in each region through the complementary emission characteristics of the individual materials.
2Measurement precision
If multiple fluorescent materials are combined to match reference light sources, then color rendering indices are improved, but the adjustment of color components becomes complicated
Solution Approach 1:
The patent specifies precise content ratio ranges for each fluorescent material (first: 3.0-55.0%, second: 20.0-50.0%, third: 30.0-70.0%, fourth: 1.0-20.0%) to systematically control the color components. By defining these parameter ranges, the complex adjustment process is standardized, making it easier to achieve optimal color rendering while matching reference light sources with correlated color temperatures of 2,856K or 6,504K.
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 device achieves excellent color rendering indices, with general color rendering index Ra of 80 or more and special indices R9 to R15 of 40 or more, effectively matching reference light sources across different applications.
Implementation Method 1
a light emitting element having a light emission peak wavelength within a range of 430 nm or more and 470 nm or less
Implementation Method 2
a fluorescent member, the light emitting device emitting light having a correlated color temperature in a range of 3,500 K or more and 4,500 K or less, the fluorescent member containing a first fluorescent material that contains an Eu-activated alkaline earth aluminate
Data Source
AI summary
A light emitting device that is capable of achieving excellent color rendering property is provided. The light emitting device contains a light emitting element having a light emission peak wavelength within a range of 430 nm or more and 470 nm or less, and a fluorescent member. The fluorescent member contains a first fluorescent material that contains an Eu-activated alkaline earth aluminate, a second fluorescent material that contains a Mn-activated fluorogermanate, a third fluorescent material that contains a Ce-activated rare earth aluminate, and a fourth fluorescent material that contains an Eu-activated silicon nitride having Al and at least one of Sr and Ca.