Phosphor Composition for Stable LED Color Conversion
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Solution Overview
Problem
Existing conversion LEDs for general lighting and backlighting face challenges due to fluctuations in the peak wavelength of semiconductor chips, leading to inconsistent color rendering and efficiency, especially under varying temperature and current conditions. Additionally, current phosphors used in backlighting applications have limitations such as broad emission spectra, low quantum efficiency, and high production costs.
Innovation Solution
A lighting device incorporating a phosphor with a specific 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, where MA, MB, MC, MD, TA, TB, TC, TD, TE, TF, XA, XB, XC, and XD represent various metal and non-metal elements, and E represents activators like Eu, Ce, Yb, and Mn. This phosphor is designed to have a balanced composition that enhances stability, absorptivity, and emission properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional phosphors (yttrium aluminum garnet, lutetium aluminum garnet, or β-SiAlON) are used for backlighting, then narrowband emission in the green spectral range can be achieved, but the production costs become very high due to expensive equipment and high temperature requirements
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material by incorporating specific ratios of silicon, aluminum, oxygen, and nitrogen along with rare earth activators (Eu, Ce, Yb, Mn). This compositional parameter change enables achieving narrowband emission properties without requiring the extreme production conditions needed for conventional phosphors like β-SiAlON
Solution Approach 2:
The patent creates a composite phosphor material combining multiple elements (Si, Al, O, N, and rare earth metals) in specific proportions. This composite approach allows the material to exhibit narrowband emission characteristics similar to expensive conventional phosphors but can be produced through more economical synthesis routes
2Use of energy by moving object
If semiconductor chips with blue primary radiation are used for general lighting, then high luminous efficiency can be achieved, but fluctuations in peak wavelength occur under variable operating temperatures and forward currents, leading to changes in color locus and color rendering
Solution Approach 1:
The patent utilizes phosphors with specific emission characteristics (narrow bandwidth, appropriate peak wavelengths in green and red regions) that can compensate for semiconductor chip wavelength shifts. By carefully selecting and combining phosphors with complementary emission properties, the overall color output remains stable despite variations in the blue LED's peak wavelength under different operating conditions
Solution Approach 2:
The patent implements a binning and sorting system that measures and categorizes semiconductor chips based on their actual color locus and wavelength characteristics. This feedback mechanism allows for matching chips with appropriate phosphor combinations to achieve consistent color rendering across multiple devices, compensating for manufacturing variations and operating condition changes
3Ease of manufacture
If phosphors with broad emission spectra are used in backlighting applications, then production costs are reduced, but the achievable color space is restricted and efficiency is reduced due to considerable filter losses
Solution Approach 1:
The patent fundamentally changes the emission spectrum parameters of the phosphor material through controlled composition (Si-Al-O-N system with rare earth activators). This results in narrowband emission with small full width at half maximum, enabling wide color space coverage without requiring additional filtering that would cause efficiency losses
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 proposed phosphor achieves stable and efficient conversion of primary radiation into secondary radiation, leading to improved color rendering, reduced production costs, and enhanced performance across various lighting applications, including general lighting and backlighting.
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 includes 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(X D)n:E. 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.