Europium Nitride Manganese Fluoride Phosphor Composition for Backlight Modules
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Solution Overview
Problem
Backlight modules using periodical driving methods suffer from light residue issues due to prolonged light emission after the light source is turned off, affecting image quality and dynamic contrast in liquid crystal displays.
Innovation Solution
A phosphor composition comprising europium-doped nitride and manganese-doped fluoride phosphor powders, with a weight ratio between 17.5% to 22.5%, is used to convert the light spectrum, reducing light residue time and enhancing red color saturation, thereby improving display performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodical driving method is used to increase dynamic contrast, then motion blur is prevented, but light residue problem occurs
Solution Approach 1:
The patent changes the temporal characteristics of light emission by using a phosphor with ultra-short afterglow duration. The specific parameter changed is the light decay time constant, reduced to less than 10 milliseconds, which allows the backlight to effectively turn off between scanning periods, eliminating light residue while maintaining high dynamic contrast performance
Solution Approach 2:
The patent employs a composite phosphor system combining europium-doped nitride phosphor and manganese-doped fluoride phosphor. This composite material achieves both high color saturation (color purity > 0.8) and ultra-short afterglow characteristics, resolving the contradiction between maintaining image quality and eliminating light residue in periodical driving modes
2Object-generated harmful factors
If light source is turned off quickly to eliminate light residue, then image quality improves, but color saturation may be compromised
Solution Approach 1:
The patent uses a composite phosphor system where europium-doped nitride phosphor provides dominant red emission with high color purity (>0.8), while manganese-doped fluoride phosphor contributes to overall luminosity. This composite structure maintains excellent color saturation even with ultra-short afterglow duration of less than 10 milliseconds
Solution Approach 2:
The patent optimizes the phosphor composition ratios and excitation wavelength parameters to achieve simultaneous optimization of color saturation and decay time. By adjusting the phosphor blend ratio and selecting appropriate excitation wavelengths, the system achieves color purity >0.8 while maintaining afterglow duration <10ms
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 composition effectively reduces light residue time to less than 10 milliseconds, eliminating flicker perception at frequencies above 60 Hz and enhancing color saturation, enabling better display effects and high-dynamic range functionality.
Implementation Method 1
The phosphor is disposed at at least one side of the light emitting body, and the light having the first spectrum is converted into light having a second spectrum after passing through the phosphor
Data Source
AI summary
A phosphor includes a europium-doped nitride phosphor powder and a manganese-doped fluoride phosphor powder. The weight ratio of the europium-doped nitride phosphor powder to the manganese-doped fluoride phosphor powder is in a range of 17.5% to 22.5%.