Silicate Phosphor Mixture for Adjustable CCT and CRI
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Solution Overview
Problem
Conventional white light emitting devices using YAG:Ce phosphor have a fixed correlated color temperature (CCT) and low color rendering index (CRI), limiting their ability to display various color feelings and closely mimic natural light.
Innovation Solution
A light emitting device incorporating a mixture of yellow silicate-based and green silicate-based phosphors, with specific chemical formulas such as Sr3-xSiO5:Eu2+x and Ba2-xSiO4:Eu2+x, Ca1-xMgSi2O7:Eu2+x, or Sr2-xSiO4:Eu2+x, which are excited by a blue light emitting chip to produce a wide range of emission peaks, allowing adjustable CCT and CRI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If YAG:Ce phosphor is used in conventional white light emitting devices, then the device structure is simple and manufacturing is easy, but the correlated color temperature (CCT) is fixed and color rendering index (CRI) is low
Solution Approach 1:
The patent combines yellow silicate-based phosphor and green silicate-based phosphor in a single phosphor layer to achieve both ease of manufacture and adjustable CCT. The yellow phosphor provides the base white light conversion while the green phosphor extends the spectral coverage and enables CCT adjustment, merging the functions of multiple phosphors into one integrated layer that maintains manufacturing simplicity.
Solution Approach 2:
The invention uses composite phosphor materials consisting of silicate-based phosphors with specific chemical compositions (e.g., Sr3-x-yLaxMg1-ySi2O7:Eu2+, Ba2-x-yLaxMg1-ySi2O7:Eu2+). These composite materials provide both the ease of manufacture through single-layer deposition and the versatility of adjustable CCT through compositional control of the phosphor mixture.
2Ease of manufacture
If YAG:Ce phosphor is used in conventional white light emitting devices, then the device structure is simple, but the color rendering index (CRI) is low
Solution Approach 1:
The patent merges yellow silicate-based phosphor and green silicate-based phosphor in one layer to simultaneously maintain manufacturing simplicity and improve color rendering. The green phosphor component fills the spectral gap in the yellow phosphor's emission, providing better color rendering across the visible spectrum while keeping the device structure simple.
Solution Approach 2:
The composite silicate-based phosphor materials with controlled compositions (containing elements like Sr, Ba, La, Mg, Si, O, and activators like Eu2+) provide enhanced color rendering properties. The specific compositional ratios and activator concentrations are optimized to achieve high CRI while maintaining ease of manufacture through single-layer fabrication.
3Device complexity
If a single phosphor type is used, then the device structure is simple, but the emission spectrum is limited
Solution Approach 1:
The patent combines yellow silicate-based phosphor and green silicate-based phosphor within a single phosphor layer, achieving broad emission spectrum coverage without increasing device complexity. The yellow phosphor emits in the 550-580nm range while the green phosphor emits in the 500-540nm range, together providing comprehensive spectral coverage that mimics natural light.
Solution Approach 2:
The composite phosphor system uses silicate-based materials with specific chemical formulations that inherently provide broad emission spectra. The materials' crystal structures and activator ions are selected to emit across multiple wavelength ranges, achieving wide spectral coverage while maintaining a simple single-layer device structure.
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 a wider range of adjustable CCT and elevated CRI, enabling light emission closest to natural light, enhancing product quality and application versatility.
Implementation Method 1
a blue light emitting chip
Implementation Method 2
a first silicate-based phosphor which emits a second light having a first centered emission peak using the first light; and a second silicate-based phosphor which emits a third light having a second centered emission peak using the first light
Data Source
AI summary
Provided is a light emitting device including a light emitting chip, and a phosphor through which a light emitting from the light emitting chip at least partially passes such that the light is converted into lights having at least two different wavelengths and emitted. The light emitting device emits white light using the phosphor.