Red Wavelength Conversion Material for Narrow-Spectrum LCD Backlights
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Solution Overview
Problem
Current red fluorescent materials used in LCDs face challenges in achieving both gamut coverage and lumen efficiency due to physical limitations, resulting in reduced color purity and afterimage phenomena.
Innovation Solution
A red wavelength conversion material with a general formula MmAaBbCcDdEe:ESxREy, where M, A, B, C, D, and E are specific elements, and ES and RE are selected from certain groups, with a proportion of element D greater than or equal to 50%, excited by blue or ultraviolet light to emit light with a peak wavelength between 610 nm and 655 nm, and a narrow full width at half maximum (FWHM) spectral characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a 620 nm wavelength red fluorescent material is used to achieve wavelength close to maximum stimulus value, then lumen efficiency is improved, but gamut coverage is sacrificed and color purity is reduced due to overlap with green light area
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of elements in the fluorescent material formula (Ca, Sr, Ba)mAaBbCcDdEe:ESxREy, where element D (O, S, or Se) constitutes 50-80% of the total. By adjusting these compositional parameters and conducting two-stage sintering processes at different temperatures and atmospheres, the patent achieves a narrow spectral FWHM of 80-120 nm while maintaining high lumen efficiency, thus resolving the contradiction between color purity and lumen efficiency
Solution Approach 2:
The patent employs composite materials by combining multiple elements (M: Ca/Sr/Ba, A: Mg/Mn/Zn/Cd, B: B/Al/Ga/In, C: Si/Ge/Ti/Hf, D: O/S/Se, E: N/P) with rare earth elements (ES: Eu/Sm/Yb, RE: Ce/Pr/Nd/Sm/Eu/Gd/Tb/Dy/Ho/Er/Tm) in specific proportions. This multi-element composite structure enables simultaneous optimization of spectral narrowness, color purity, and conversion efficiency, overcoming the limitations of single-component fluorescent materials
2Ease of manufacture
If conventional red fluorescent materials are used, then manufacturing is simpler, but afterimage phenomena occur and spectral width is large
Solution Approach 1:
The patent applies inert atmosphere by conducting the second high-temperature sintering process in a reducing atmosphere (nitrogen or argon). This controlled atmospheric environment prevents oxidation of the fluorescent material during sintering, eliminates afterimage phenomena caused by material degradation, and ensures stable spectral characteristics while maintaining manufacturing feasibility through standard ceramic processing techniques
3Manufacturing precision
If spectral width is reduced to improve color purity, then color purity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the sintering process into two distinct stages: first high-temperature sintering (forming the base structure with elements M, A, B, C, D, E) followed by second high-temperature sintering in reducing atmosphere (incorporating rare earth elements ES and RE). This segmented approach enables precise control of spectral characteristics while keeping each individual process step manageable and industrially feasible
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 material achieves higher color purity and lumen efficiency with tunable wavelength and spectral characteristics, reducing manufacturing costs and eliminating afterimage issues, suitable for backlight modules and high CRI lighting.
Implementation Method 1
The wavelength conversion material includes a general formula (I) and satisfies a condition (II). The general formula (I) is MmAaBbCcDdEe:ESxREy. The wavelength conversion material is excited by a blue light source or an ultraviolet light source to emit a light.
Data Source
AI summary
The wavelength conversion material includes a general formula (I) MmAaBbCcDdEe:ESxREy and satisfies a condition (II) that a proportion of D for the wavelength conversion material greater than or equal to 50%. M is selected from a group consisting of Ca, Sr and Ba. A is selected from a group consisting of elements Mg, Mn, Zn and Cd. B is selected from a group consisting of elements B, Al, Ga and In. C is selected from a group consisting of Si, Ge, Ti and Hf. D is selected from a group consisting of elements 0, S and Se. E is selected from a group consisting of elements N and P. ES is selected from a group consisting of divalent Eu, Sm and Yb. RE is selected from a group consisting of trivalent Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm.