Organic EL Surface Light Source with Concavo-Convex Structure
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Solution Overview
Problem
Double-side emission type surface light source devices with concavo-convex structures face challenges in achieving high light extraction efficiency while maintaining the see-through feature, as conventional structures increase haze and compromise transparency.
Innovation Solution
A surface light source device with a concavo-convex structure on the light output surface, where the inclined surface portion is tilted at an angle of 80° to 90° and the projected area is no more than 0.1 times the total area of the flat surface portions, allowing for efficient light extraction while preserving transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional concavo-convex structure is provided on the light output surface of a double-side emission type surface light source device, then light extraction efficiency is improved, but haze increases and the see-through feature is compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the inclination angle of the inclined surface portion (80° to 90°) and the area ratio between inclined and flat surface portions (not more than 0.1 times). These parameter optimizations enable the concavo-convex structure to extract light effectively while minimizing haze generation, thus resolving the contradiction between light extraction efficiency and see-through feature maintenance.
Solution Approach 2:
The patent implements local quality by creating distinct regions with different functions: the inclined surface portions (with small projected area) are optimized for light extraction, while the flat surface portions (with large area) are optimized for maintaining transparency and see-through features. This spatial differentiation of surface properties allows simultaneous achievement of high light extraction efficiency and low haze.
2Productivity
If the inclined surface portion area is increased to improve light extraction, then light extraction efficiency improves, but the see-through feature deteriorates
Solution Approach 1:
The patent resolves this contradiction by changing the area ratio parameter to be not more than 0.1 times between the projected area of inclined surface portions and the total area of flat surface portions. This precise parameter control ensures that the inclined surfaces provide sufficient light extraction capability while the dominant flat surfaces maintain the see-through feature, preventing deterioration of transparency.
3Productivity
If the inclination angle is reduced to increase light extraction, then light extraction efficiency improves, but mechanical strength decreases
Solution Approach 1:
The patent resolves this contradiction by optimizing the inclination angle parameter to be between 80° and 90°. This steep angle range maximizes light extraction efficiency by creating appropriate refraction angles while simultaneously minimizing the reduction of mechanical strength that would occur with shallower angles. The flat surface portions also contribute to mechanical strength by providing a continuous load-bearing surface.
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 enables high light extraction efficiency while maintaining the see-through feature, suppressing haze and enhancing mechanical strength by controlling the area ratio and inclination angle of the concavo-convex structure.
Implementation Method 1
a concavo-convex structure having flat surface portions and an inclined surface portion tilted relative to the flat surface portions
Implementation Method 2
the reflecting layer reflects light emitted from the organic EL element to the side that is opposite to the light output surface
Data Source
AI summary
A surface light source device including an organic EL element of a double-side emission type and a light output surface structure layer provided on at least one surface of the organic EL element, wherein the light output surface structure layer includes a concavo-convex structure on a surface opposite to the organic electroluminescent element, the concavo-convex structure having flat surface portions parallel to the surface and an inclined surface portion tilted relative to the flat surface portions, and a projected area formed by projecting the inclined surface portion in a direction perpendicular to the flat surface portions onto a plane parallel to the flat surface portions is not more than 0.1 times a total area of the flat surface portions.