Fluorescent Substrate Reflecting Film Light Extraction
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Solution Overview
Problem
Conventional methods for manufacturing large-size organic electroluminescence (EL) displays face challenges such as mask size limitations, alignment accuracy issues, light emission losses, and increased power consumption due to isotropic light emission from fluorescent layers, leading to poor color purity and luminance efficiency.
Innovation Solution
A fluorescent substrate with a reflecting film on both side surfaces and the excitation light incident surface, which transmits the excitation light peak wavelength and reflects the emitted light peak wavelength, enhancing light extraction efficiency by redirecting isotropically emitted light back into the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shadow mask method is used to form different light-emitting layers, then full color image display is achieved, but mask processing accuracy and alignment accuracy deteriorate with large substrate sizes
Solution Approach 1:
The patent extracts the color filtering function from the shadow mask process by using a color filter layer that is deposited separately after the organic EL layer formation. This eliminates the need for precise shadow mask alignment while still achieving full color display, as the color filter is applied uniformly across the entire substrate rather than requiring pixel-by-pixel precision.
Solution Approach 2:
The color filter layer is formed in advance as a separate step before final assembly, allowing for easier manufacturing and alignment. The filter layer is deposited over the entire substrate area, eliminating the need for complex mask alignment procedures during the organic EL layer formation process.
2Area of stationary object
If mask size is increased to match large substrate size, then full substrate coverage is achieved, but mask processing and alignment accuracy deteriorate
Solution Approach 1:
The patent removes the shadow mask from the process entirely and replaces it with a color filter layer that is deposited using different techniques (such as spin coating or inkjet printing) that do not require large-scale mask fabrication. This extraction of the color filtering function eliminates the fundamental limitation of mask size and processing accuracy.
3Manufacturing precision
If insulating layer width is increased to prevent light mixing, then color purity is maintained, but aperture ratio decreases
Solution Approach 1:
The patent introduces a light-blocking layer as an intermediary element with optimized width that prevents light leakage more effectively than conventional insulating layers. This layer is positioned strategically to block light from adjacent pixels while minimizing the impact on the aperture ratio, achieving better color isolation with smaller non-light-emitting areas.
4Illumination intensity
If fluorescent layer emits light isotropically, then light is emitted in all directions, but light extraction efficiency decreases
Solution Approach 1:
The patent applies a micro-lens array structure that creates local optical properties variations across the substrate. Each micro-lens focuses light from the fluorescent layer in a specific direction toward the viewer, converting the isotropic emission into directed light output. This local modification of light propagation improves extraction efficiency while maintaining the benefit of isotropic emission at the source.
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
This solution significantly improves light-emitting efficiency, reducing power consumption and manufacturing costs while maintaining color purity and luminance across various viewing angles.
Implementation Method 1
a reflecting film which is provided both on side surfaces of the fluorescent layer and on a surface of the fluorescent layer on which excitation light is incident, the reflecting film transmitting a component having a peak wavelength of the excitation light and reflecting a component having a peak wavelength of light emitted from the fluorescent layer
Implementation Method 2
a fluorescent layer which emits light by receiving excitation light
Data Source
AI summary
A fluorescent substrate (5) of the present invention includes: a fluorescent layer (3) which emits light by receiving excitation light; and a reflecting film (10) being provided both (i) on a side surface(s) of the fluorescent layer (3) and (ii) on a surface of the fluorescent layer (3), on which surface the excitation light is incident, the reflecting film (10) (I) transmitting a component having a peak wavelength of the excitation light, and (II) reflecting a component having a peak wavelength of the light emitted from the fluorescent layer (3).