Fluorescent Substance for Field Emission Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fluorescent substances used in field emission displays, such as sulfide phosphors, decompose under excitation, leading to degradation of heat filaments and reduced luminance, especially for blue emissions, which affects the color fidelity of displayed images over time.
Innovation Solution
A fluorescent substance with a specific composition and crystal structure, comprising a metal element, trivalent and tetravalent elements, and luminescence center elements, is developed, which maintains high quantum efficiency and emission intensity even at elevated temperatures, characterized by chemical bond lengths within a specific range based on the Sr3Al3Si13O2N21 crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sulfide phosphors are used in field emission displays, then high emission efficiency can be achieved, but the phosphors decompose under excitation causing filament degradation and reduced luminance
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material by incorporating rare earth elements (europium, terbium, dysprosium) into a specific oxide matrix (2MgO·SiO2·nSiO2 where n=2-6). This compositional parameter change transforms the phosphor from conventional sulfide-based materials to oxide-based materials with superior stability while maintaining high emission efficiency through the luminescent properties of the rare earth dopants.
Solution Approach 2:
The patent creates a composite phosphor material consisting of a base oxide matrix (2MgO·SiO2·nSiO2) combined with rare earth element dopants (Eu, Tb, Dy). This composite structure combines the structural stability of the oxide matrix with the luminescent properties of the rare earth elements, achieving both high emission efficiency and resistance to decomposition under electron beam excitation.
2Illumination intensity
If conventional phosphors are used, then initial luminance can be achieved, but luminance decreases over time due to deterioration
Solution Approach 1:
The patent modifies the chemical composition parameters by using oxide-based materials with specific stoichiometric ratios (2MgO·SiO2·nSiO2) instead of conventional sulfide phosphors. This parameter change results in materials with higher thermal and chemical stability, preventing the decomposition and luminance deterioration that occurs over time in conventional phosphors while maintaining high initial luminance through rare earth dopant optimization.
3Illumination intensity
If blue fluorescent substances are used, then blue color emission can be achieved, but they deteriorate more rapidly affecting color fidelity
Solution Approach 1:
The patent changes the chemical composition from conventional blue phosphor materials to oxide-based phosphors with specific rare earth dopants (particularly europium and terbium) in the 2MgO·SiO2·nSiO2 matrix. This compositional parameter change provides superior chemical and thermal stability that prevents the rapid deterioration of blue phosphors, maintaining color fidelity and blue luminance stability over extended operation periods.
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 fluorescent substance exhibits excellent quantum efficiency and temperature stability, preventing a significant decrease in emission intensity, thus providing high-quality, long-lasting color performance in field emission displays.
Implementation Method 1
emitting luminescence having a peak in the wavelength range of 490 to 580 nm when excited with light in the wavelength range of 250 to 500 nm
Data Source
AI summary
The present invention provides a fluorescent substance excellent both in quantum efficiency and in temperature characteristics, and also provides a light-emitting device utilizing the fluorescent substance. This fluorescent substance contains an inorganic compound comprising a metal element M, a trivalent element M1 other than the metal element M, a tetravalent element M2 other than the metal element M, and either or both of O and N. In the inorganic compound, the metal element M is partly replaced with a luminescence center element R. The crystal structure of the fluorescent substance is basically the same as Sr3Al3Si13O2N21, but the chemical bond lengths of M1-N and M2-N are within the range of ±15% based on those of Al—N and Si—N calculated from the lattice constants and atomic coordinates of Sr3Al3Si13O2N21, respectively. The fluorescent substance emits luminescence having a peak in the range of 490 to 580 nm when excited with light of 250 to 500 nm.