Phosphor Composition for Stable Color Rendering in Conversion LEDs
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Solution Overview
Problem
Existing conversion LEDs for general lighting and backlighting face issues with fluctuations in color rendering due to variations in the peak wavelength of semiconductor chips, leading to inconsistent optical properties, and current phosphors like yttrium aluminum garnet and β-SiAlON have limitations in efficiency and production costs.
Innovation Solution
A lighting device utilizing a phosphor with a specific molecular formula that includes elements such as Eu, Ce, and Yb, which can be tailored to achieve stable and efficient emission across various spectral ranges, allowing for precise control of peak wavelength and full width at half maximum, thereby improving color rendering and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional phosphors like yttrium aluminum garnet or β-SiAlON are used, then narrowband emission can be achieved, but production costs increase and quantum efficiency decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by incorporating rare earth elements (Eu, Ce, Yb) into a silicate matrix, replacing conventional phosphors like yttrium aluminum garnet and β-SiAlON. This composition change enables precise control of emission wavelength and full width at half maximum while simplifying production and improving quantum efficiency
Solution Approach 2:
The patent creates a composite phosphor material combining silicate base (Li, Na, K) with rare earth elements (Eu, Ce, Yb) in specific ratios. This composite structure achieves narrowband emission characteristics comparable to expensive conventional phosphors while being more cost-effective and efficient
2Reliability
If semiconductor chips are sorted with narrow tolerances to avoid fluctuations, then color rendering improves, but manufacturing complexity and costs increase
Solution Approach 1:
The patent changes the phosphor's emission characteristics by controlling rare earth element content and ratios, making the overall emission less sensitive to semiconductor chip wavelength variations. This reduces the need for strict binning while maintaining stable color rendering
Solution Approach 2:
The phosphor acts as an intermediary that converts semiconductor chip emissions into a more stable overall output. By carefully selecting phosphor composition, the patent creates a buffer against chip wavelength fluctuations, reducing the impact on final color rendering
3Adaptability or versatility
If variable operating temperatures and forward currents are applied to semiconductor chips, then adaptability improves, but optical property fluctuations increase
Solution Approach 1:
The patent selects phosphor materials with specific thermal and electrical characteristics that maintain stable emission under variable operating conditions. The silicate-rare earth composition is chosen for its stability across temperature and current variations, compensating for semiconductor chip fluctuations
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 phosphor enables stable and efficient conversion LEDs with improved color rendering and reduced production costs by allowing for precise control of emission characteristics, making them suitable for both general lighting and 'color on demand' applications.
Implementation Method 1
a phosphor configured at least partly to convert the electromagnetic primary radiation into an electromagnetic secondary radiation
Data Source
AI summary
A lighting device is specified. The lighting device comprises a phosphor having the general molecular formula (MA)a(MB)b(MC)c(MD)d(TA)e(TB)f(TC)g(TD)h(TE)i(TF)j(XA)k(XB)l(XC)m(XD)n:E. In this case, MA is selected from a group of monovalent metals, MB is selected from a group of divalent metals, MC is selected from a group of trivalent metals, MD is selected from a group of tetravalent metals, TA is selected from a group of monovalent metals, TB is selected from a group of divalent metals, TC is selected from a group of trivalent metals, TD is selected from a group of tetravalent metals, TE is selected from a group of pentavalent elements, TF is selected from a group of hexavalent elements, XA is selected from a group of elements which comprises halogens, XB is selected from a group of elements which comprises O, S and combinations thereof, XC=N and XD=C and E=Eu, Ce, Yb and/or Mn. The following furthermore hold true: a+b+c+d=t; e+f+g+h+i+j=u; k+l+m+n=v; a+2b+3c+4d+e+2f+3g+4h+5i+6j−k−2l−3m−4n=w; 0.8≤t≤1; −3.5≤u≤4; 3.5≤v≤4; (−0.2)≤w≤0.2 and 0≤m<0.875 v and/or v≥l>0.125 v.