Color Conversion Sheet With Blue-Light Absorption for Phosphor Stability
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Solution Overview
Problem
Existing organic phosphors in LCDs deteriorate due to short-wavelength blue light, affecting emission characteristics, luminance, and causing eye damage, while cadmium-based nano-inorganic particles pose environmental concerns.
Innovation Solution
A color conversion sheet with a wavelength conversion layer containing organic phosphors and a light absorption layer that shields 60% or more of wavelengths below 410 nm, absorbs 10% or more of wavelengths between 430 nm and 460 nm, and transmits 80% or more of wavelengths above 460 nm, using organic light absorbers like anthracene-based compounds to prevent deterioration and eye damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic phosphors are used in the wavelength conversion layer, then high color gamut and excellent luminance characteristics are achieved, but the organic phosphors deteriorate due to short-wavelength blue light
Solution Approach 1:
A light absorption layer containing organic light absorbers is introduced as an intermediary component between the blue LED and the organic phosphor. This layer selectively absorbs short-wavelength blue light (410 nm or less) while transmitting longer wavelength blue light (460 nm or more) that is necessary for phosphor excitation, thereby protecting the phosphor from deterioration without compromising luminance characteristics
Solution Approach 2:
The backlight unit is segmented into distinct functional layers: a blue LED layer, a light absorption layer with organic light absorbers, and a wavelength conversion layer with organic phosphors. This segmentation allows each layer to perform its specific function independently - the absorption layer handles harmful short-wavelength light while the conversion layer handles useful longer wavelength light
2Reliability
If cadmium-based nano-inorganic particles are used, then high color gamut is achieved, but environmental concerns and moisture vulnerability arise
Solution Approach 1:
The invention changes the material parameter from inorganic quantum dots to organic phosphors, which have different chemical composition and structural properties. Organic phosphors contain carbon-based molecular structures that are inherently more resistant to moisture and do not contain toxic cadmium, while still achieving high color gamut through appropriate molecular design and selection of emission wavelengths
3Device complexity
If short-wavelength blue light is not removed, then the display structure remains simple, but organic phosphor deterioration and eye damage occur
Solution Approach 1:
The light absorption layer serves multiple functions simultaneously: it protects the organic phosphor from deterioration by absorbing harmful short-wavelength blue light, and it protects human eyes from retinal damage by filtering out the same harmful wavelengths. This multi-functionality is achieved through the selective absorption characteristics of organic light absorbers in the 410 nm wavelength region
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 solution effectively protects organic phosphors from blue light degradation, maintains luminance and color stability, and prevents eye damage, ensuring high-performance and safety in LCDs.
Implementation Method 1
a light absorption layer which is located on one surface of the wavelength conversion layer and in which an organic light absorber is dispersed
Implementation Method 2
in the case of organic phosphors, although they may emit light by absorbing light irradiated from the blue light-emitting diode (LED) of the display
Data Source
Figure 1~2
Figure 3
AI summary
A color conversion sheet according to an embodiment of the present invention comprises: a wavelength conversion layer in which an organic phosphor is dispersed in a resin matrix; and a light absorption layer in which an organic light absorber located on one side of the wavelength conversion layer is dispersed in a binder resin. Thus, the color conversion sheet uses environmentally safe organic phosphors by absorbing short-wavelength blue light that deteriorates organic phosphors without affecting the emission characteristics of the organic phosphors included in the wavelength conversion layer, has excellent color reproduction rate and luminance characteristics, undergoes little color change when irradiated with light and has excellent luminance reliability, not only at room temperature but also in high-temperature environments, and has excellent performance in terms of eye protection.