Light Emitting Display Substrate with Uneven Portion for Light Extraction
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Solution Overview
Problem
Light emitting display devices suffer from low light extraction efficiency due to total reflection at interfaces, leading to reduced luminance and increased power consumption.
Innovation Solution
A light emitting display apparatus with a substrate having pixel areas with opening areas featuring uneven portions, including concave and protruding structures, which alter the light propagation path to enhance extraction efficiency, with specific roughness averages and skewness values for the uneven portions to optimize light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light emitting elements are used to display images, then the display apparatus achieves high response speed and low power consumption, but light extraction efficiency is reduced due to total reflection at interfaces
Solution Approach 1:
The patent applies curvature by forming an uneven portion with concave and convex patterns on the lower surface of the substrate. This curved/uneven structure redirects light that would otherwise undergo total reflection at the planar interface, enabling it to escape through the side surfaces of the uneven portion. The curvature transforms the flat interface into a multi-faceted structure that exploits refraction and internal reflection to improve light extraction efficiency while maintaining low power consumption operation.
2Illumination intensity
If light is emitted from the light emitting layer, then the display apparatus produces visible output, but about 80% of light is confined inside due to total reflection
Solution Approach 1:
The patent segments the原本 continuous planar interface into discrete concave and convex portions. By dividing the light extraction surface into multiple separated regions with varying depths and shapes, the structure creates multiple light extraction pathways. Light that fails to escape at one interface region can be redirected to other regions, increasing the overall probability of light extraction and thereby improving luminance output.
Solution Approach 2:
The patent transitions from a two-dimensional planar interface to a three-dimensional uneven structure with varying heights and depths. This dimensional change introduces vertical variation (z-axis) to the light extraction interface, creating additional extraction pathways through the side walls of the concave and convex portions. This 3D structure enables light to escape through multiple directions and planes, significantly improving light extraction efficiency and luminance.
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
Improves light extraction efficiency, enhancing luminance and reducing power consumption by effectively redirecting and extracting light that would otherwise be trapped through total reflection.
Implementation Method 1
some light of light emitted from a light emitting layer is not externally discharged due to total reflection or the like at an interface between the light emitting layer and an electrode and/or an interface between the substrate and an air layer
Data Source
AI summary
A light emitting display apparatus is disclosed, which can improve light extraction efficiency of light emitted from a light emitting diode. The light emitting display apparatus comprises a substrate including a plurality of pixel areas having an opening area, an uneven portion arranged in the opening area, and a light emitting diode arranged over the uneven portion, the uneven portion may have roughness average value of about 0.19 to about 0.29 for a unit size.