Tiled OLED Edge Light Extraction Structure
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Solution Overview
Problem
Tiled flat-panel displays face challenges in reducing the visibility of edge seams due to trapped light and inefficiencies in light extraction, leading to a noticeable discontinuity and reduced luminance at the edges of display tiles.
Innovation Solution
A light-extraction structure is formed in the edge gap of the substrate, partially exterior to the LED pixels, using diffusive surfaces, refractive particles, lenslets, or angled mirrors to extract trapped light and reduce contrast between the edge seam and the active display area, thereby hiding the edge seam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple display tiles are butted together in an array, then the display size is increased, but edge seams become visible and create visual discontinuities
Solution Approach 1:
A light extraction structure is introduced as an intermediary element in the edge gap between display tiles. This structure extracts trapped light from the edge region and redirects it to fill the edge gap, serving as a mediator that optically connects adjacent tiles and eliminates the visual discontinuity caused by edge seams.
Solution Approach 2:
The patent modifies the optical parameters of the edge gap region by introducing a light extraction structure with specific refractive index properties. This changes the light distribution parameters in the edge region, extracting trapped light and redistributing it to match the luminance of surrounding pixels, thereby hiding the edge seam.
2Loss of energy
If light is emitted at angles not near perpendicular to the front surface, then light extraction efficiency is reduced, but light is trapped and lost
Solution Approach 1:
The patent converts the harmful effect of trapped light (which would otherwise be lost) into a beneficial effect. The light extraction structure captures light that was previously trapped by total internal reflection and redirects it to escape through the front surface, transforming energy loss into useful light output.
Solution Approach 2:
The light extraction structure changes the optical parameters at the edge gap, creating conditions that allow trapped light to escape. By modifying the refractive index environment and light path geometry, the structure enables light that would have been trapped to now contribute to the display's useful output.
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 light-extraction structure effectively reduces the visibility of edge seams by matching the luminance and color of extracted light with the surrounding pixels, enhancing the visual uniformity and brightness of the display.
Implementation Method 1
much of the light output from the light-emissive layer in the OLED is trapped due to the diffuse emission within these devices and internal reflections that occur at material boundaries
Implementation Method 2
A light-extraction structure is formed in the edge gap of the substrate, partially exterior to the LED pixels, using diffusive surfaces, refractive particles, lenslets, or angled mirrors to extract trapped light
Data Source
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AI summary
An area-emissive light-emitting diode (LED) device (10) comprises a substrate (30) having an internal substrate surface (34), an external substrate surface (35) opposite the internal substrate surface, and a substrate edge (36); an array of area-emissive LED pixels (14) formed on the internal substrate surface (34) with an edge gap (20) between the substrate edge (36) and the LED pixel (14A) on the internal substrate surface (34) nearest the substrate edge (36); and a light-extraction structure (60) formed in the edge gap (20) and at least partially exterior to the LED pixels (14, 14A).