Red Light-Emitting Fluorescent Substance for LED Color Rendition
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Solution Overview
Problem
Existing white light-emitting LED devices lack red color emission, resulting in poor color rendition, and face challenges with luminance and temperature characteristics, which affect their efficiency and color accuracy.
Innovation Solution
A red light-emitting fluorescent substance with a specific composition (M1-xECx)aM1bAlOcNd, where M and EC are selected elements, and x, a, b, c, and d are within specific ranges, is developed to emit luminescence in the 620-670 nm range, improving color rendition and temperature stability when combined with blue and yellow phosphors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If increased electric power is applied to improve luminance, then luminance output increases, but device operating temperature rises and emission efficiency drops
Solution Approach 1:
The patent changes the chemical composition parameters of the fluorescent substance by incorporating specific rare earth elements (Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, Tl, Pb, Bi, or Fe) and controlling the ratios of M, M1, Al, O, and N to optimize emission efficiency across different operating temperatures. This compositional parameter optimization allows the material to maintain higher emission efficiency even when operated at elevated temperatures resulting from increased electric power input.
Solution Approach 2:
The patent creates a composite fluorescent substance with the general formula (M1-xECx)aM1bAlOcNd, combining multiple elements with specific functions: M and M1 provide the base structure, Al contributes to luminescence properties, O and N adjust the band gap and emission characteristics, and rare earth elements serve as activators. This composite structure enables the material to achieve both high luminance output and maintained emission efficiency under high power operation.
2Illumination intensity
If increased electric power is applied to improve luminance, then luminance output increases, but color balance is lost and color discrepancies occur
Solution Approach 1:
The patent optimizes the compositional parameters including the ratio of M to M1 (where M is typically alkaline earth metal and M1 is typically Si or Ge), the amount of Al, and the O/N ratio to control the emission spectrum. By precisely controlling these parameters, the fluorescent substance maintains stable color characteristics across different operating temperatures, preventing color shifts that would otherwise occur when increasing electric power for higher luminance.
3Stability of the object's composition
If red light-emitting fluorescent substance is added to improve color rendition, then color rendering index increases, but device complexity increases
Solution Approach 1:
The patent merges multiple functional elements into a single fluorescent substance formulation. The composite material (M1-xECx)aM1bAlOcNd simultaneously provides: (1) blue emission from the base structure excited by UV or blue LEDs, (2) red emission from rare earth element activators, and (3) optimized color rendering through the synergistic interaction of all components. This consolidation into one material eliminates the need for separate red phosphor layers or additional optical components, thereby improving color rendition without significantly increasing device complexity.
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 red fluorescent substance enhances the color rendering index and emission efficiency while maintaining luminance retention at high temperatures, enabling the production of LED devices with improved color accuracy and stability.
Implementation Method 1
a red light-emitting fluorescent substance... that emits luminescence having a peak in a wavelength range of 620 to 670 nm when excited by light in a wavelength range of 250 to 500 nm
Implementation Method 2
a yellow phosphor in combination... yellow luminescence from the yellow phosphor
Data Source
AI summary
The embodiment provides a red light-emitting fluorescent substance represented by the following formula (1): (M1-xECx)aM1bAlOcNd(1). In the formula (1), M is an element selected from the group consisting of IA group elements, IIA group elements, IIIA group elements, IIIB group elements, rare earth elements and IVA group elements; EC is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, Tl, Pb, Bi and Fe; M1 is different from M and is selected from the group consisting of tetravalent elements; and x, a, b, c and d are numbers satisfying the conditions of 0<x<0.2, 0.63<a<0.80, 2.1<b<2.63, 0<c@0.24 and 4<d<5, respectively. This substance emits luminescence having a peak in the wavelength range of 620 to 670 nm when excited by light of 250 to 500 nm.