Nitride Phosphor for Warm White Light with High Color Rendering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing white light emitting devices using cerium-activated yttrium aluminium garnet phosphors have low color rendering due to a lack of red light component, making it difficult to achieve illumination with low color temperature and high color rendering like 'warm white' fluorescent lamps.
Innovation Solution
A new phosphor with a crystal phase represented by the formula R3−x−y−z+w2MzA1.5x+y−w2Si6−w1−w2AlW1+w2Oy+w1N11−y−w2, where R is a rare-earth element, M is a metal element, and A is a bivalent metal element, emitting a yellow green to orange light with a large full width at half maximum, is developed, along with a production method using a nitrogen-containing atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If cerium-activated yttrium aluminium garnet phosphors are used in white light emitting devices, then the device can produce white light by combining blue light from LED and yellow light from phosphor, but the color rendering is low due to lack of red light component
Solution Approach 1:
The patent uses a composite phosphor system combining yellow-green emitting phosphor (β-SiAlON:Eu) and red emitting phosphor (CaAlSiN3:Eu) to create a multi-component material that emits both yellow-green and red light simultaneously, achieving high color rendering warm white light that cannot be obtained with single phosphor materials
Solution Approach 2:
The patent applies different phosphor materials to different regions or functions within the light emitting device - yellow-green phosphor for the primary wavelength conversion and red phosphor for enhancing the red component, allowing each material to optimize its specific function while contributing to overall color rendering
2Temperature
If existing phosphors are used to achieve low color temperature illumination, then the color temperature can be reduced, but the color rendering remains poor without sufficient red light component
Solution Approach 1:
The patent changes the spectral parameters by introducing red emitting CaAlSiN3:Eu phosphor with emission peak around 610-650nm to the phosphor system, which shifts the overall emission spectrum to include sufficient red light component while maintaining low color temperature characteristics for warm white illumination
3Illumination intensity
If nitride-based phosphors are used instead of oxides, then superior luminescent characteristics can be achieved, but production facilitation is more difficult
Solution Approach 1:
The patent changes the chemical composition parameters by using nitride-based compounds (β-SiAlON, CaAlSiN3) instead of oxide-based phosphors, which provides superior luminescent efficiency and color stability, while the production difficulty is managed through established nitride synthesis methodologies
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 new phosphor emits a fluorescence with a significant red component and large full width at half maximum, enabling the production of warm white light with high color rendering and improved luminescent characteristics for light emitting devices.
Implementation Method 1
a phosphor that emits yellow green to orange light when irradiated with light from an excitation light source such as a semiconductor luminous element
Implementation Method 2
a production method using a nitrogen-containing atmosphere
Data Source
AI summary
To provide a new phosphor of which fluorescence contains much red light component and has a large full width at half maximum, the crystal phase represented by the formula [I] is included in the phosphor. R3−x−y−z+w2MzA1.5x+y−w2Si6−w1−w2AlW1+w2Oy+w1N11−y−w1 [I] (R represents La, Gd, Lu, Y and/or Sc, M represents Ce, Eu, Mn, Yb, Pr and/or Tb, A represents Ba, Sr, Ca, Mg and/or Zn, and x, y, z, w1 and w2 are the numeric values in the following ranges: (1/7)≦̸(3−x−y−z+w2)/6<(1/2), 0<(1.5x+y−w2)/6<(9/2), 0<x<3, 0≦̸y<2, 0<z<1, 0≦̸w1≦̸5, 0≦̸w2≦̸5, and 0≦̸w1+w2≦̸5).