Blue-Wavelength Conversion Layer for High-Luminance Display Devices
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Solution Overview
Problem
Display devices face difficulties in emitting high-luminance blue light due to low standard photopic luminous efficiency of blue light with a peak wavelength of 455 nm or less, and unsatisfactory developments in electroluminescence materials for blue light with a peak wavelength longer than 455 nm.
Innovation Solution
A display device incorporating a blue light-emitting layer composed of an organic light-emitting diode or quantum-dot light-emitting diode, along with a blue-wavelength conversion layer that converts first blue light with a peak wavelength of 455 nm or less into second blue light with a peak wavelength of 490 nm or less, where the energy conversion efficiency of the blue-wavelength conversion layer satisfies the condition Sb1 < Eb × Sb2, with Sb1 and Sb2 being the standard photopic luminous efficiencies of the first and second blue lights respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If first blue light with peak wavelength of 455 nm or less is used to achieve high luminance, then the luminance can be increased, but the standard photopic luminous efficiency is low and it causes eye strain
Solution Approach 1:
The patent changes the wavelength parameter of blue light from 455 nm or less (first blue light) to longer than 455 nm but 490 nm or less (second blue light) by using a wavelength conversion layer. This parameter change achieves high luminance while improving standard photopic luminous efficiency and reducing eye strain, as second blue light has better luminous efficiency and is less harmful to eyes.
Solution Approach 2:
The patent introduces a wavelength conversion layer as an intermediary between the blue light-emitting layer and the viewer. This layer converts first blue light (455 nm or less) into second blue light (longer than 455 nm but 490 nm or less), acting as a mediator that transforms harmful high-energy blue light into beneficial lower-energy blue light while maintaining high luminance.
2Illumination intensity
If electroluminescence materials for second blue light with peak wavelength longer than 455 nm are developed, then high-luminance blue light can be emitted, but the material development has been unsatisfactory
Solution Approach 1:
Instead of directly developing difficult electroluminescence materials for second blue light, the patent uses a wavelength conversion layer as an intermediary approach. The blue light-emitting layer generates first blue light, and the wavelength conversion layer transforms it into second blue light, avoiding the need for complex material development while achieving high-luminance blue light emission.
Solution Approach 2:
The patent substitutes the direct electroluminescence material approach (mechanical/chemical system) with an optical conversion system. Instead of relying on difficult-to-develop electroluminescence materials for second blue light, the system uses a wavelength conversion layer that optically transforms first blue light into second blue light, simplifying the manufacturing process.
3Illumination intensity
If a wavelength conversion layer is introduced to convert first blue light into second blue light, then high-luminance blue light with better luminous efficiency is achieved, but the device structure becomes more complex
Solution Approach 1:
The wavelength conversion layer serves multiple functions simultaneously: it converts first blue light to second blue light, improves luminous efficiency, reduces eye strain, and maintains high luminance. This multi-functionality justifies the added structural complexity by delivering multiple benefits from a single component.
Solution Approach 2:
The patent uses a composite structure consisting of a blue light-emitting layer and a wavelength conversion layer. The wavelength conversion layer contains specific materials (such as quantum dots or phosphors) that work together with the blue light-emitting layer to achieve the desired optical properties, creating a composite system that delivers high-luminance blue light with improved efficiency.
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
Facilitates the emission of high-luminance blue light without relying on high-efficiency electroluminescence materials, achieving desirable color and reduced eye strain by enhancing the spectral radiance of light with a peak wavelength longer than 455 nm.
Implementation Method 1
a blue-wavelength conversion layer, wherein the blue light-emitting layer is configured to emit first blue light having a peak wavelength of 455 nm or less, the blue-wavelength conversion layer is provided over at least the blue light-emitting layer and is configured to convert the first blue light into second blue light having a peak wavelength that is longer than the peak wavelength of the first blue light and is 490 nm or less
Data Source
AI summary
Sb1<Eb×Sb2 is satisfied, where Eb is the energy conversion efficiency of a blue-wavelength conversion layer, where Sb1 is the standard photopic luminous efficiency of first blue light, where Sb2 is the standard photopic luminous efficiency of second blue light.