Patterned LED Escape Surface for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-emitting elements face inefficiencies in light extraction due to total internal reflection, where a substantial portion of light is absorbed within the device, and random roughening techniques lack control over light exit and re-entry probabilities.
Innovation Solution
A patterned escape surface with sloped features is designed based on the light-emitting element's emission field pattern, where the angles of inclination for these features maximize light extraction and minimize re-injection, using techniques like etching or laser slicing to create conic or pyramid features that align with the critical angle for optimal light exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a smooth escape surface is used, then the manufacturing process is simple, but a substantial portion of light is totally internally reflected and absorbed within the device
Solution Approach 1:
The escape surface is segmented into multiple discrete patterned features (protrusions or recesses) rather than being uniformly smooth or uniformly rough. Each feature is individually structured with specific geometric parameters (size, shape, spacing) to optimize light extraction while maintaining manufacturing feasibility through standardized patterning processes.
Solution Approach 2:
Different regions of the escape surface are given different local properties through the patterned features. The features are strategically positioned and dimensioned to create varying surface characteristics across the surface, with each local area optimized for its specific function in directing light extraction while maintaining overall device performance.
2Loss of energy
If random roughening techniques are used, then light extraction is improved, but control over light exit and re-entry probabilities is lost
Solution Approach 1:
The random roughness is replaced with patterned features having precisely controlled geometric parameters including size, shape, spacing, and orientation. These parameters are systematically varied to optimize light extraction efficiency while maintaining control over the angular distribution of extracted light, allowing prediction and control of light exit and re-entry probabilities.
Solution Approach 2:
The surface features are pre-designed and pre-patterned with specific geometric characteristics before the light extraction process occurs. This preliminary structuring ensures that when light encounters the surface, the interaction is predictable and controlled, eliminating the uncertainty inherent in random roughening while maintaining enhanced extraction 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
This approach significantly enhances light extraction efficiency by aligning surface features with the escape zone, reducing total internal reflection and re-entry of light, thereby optimizing the angular light extraction efficiency.
Implementation Method 1
a substantial portion of the light may strike the surface at an angle that exceeds a critical angle of the interface between the materials on either side of the surface and be totally internally reflected (TIR)
Implementation Method 2
The critical angle is determined by the indices of refraction n1 and n2 of the material at an interface between the materials
Data Source
AI summary
The escape surface of a light emitting element includes features that include sloped surfaces that have angles of inclination that are based on the direction of peak light output from the light emitting element. If the light output exhibits a number of lobes at different directions, the sloped surfaces may have a corresponding number of different angles of inclination. To minimize the re-injection of light into adjacent features, adjacent features may be positioned to avoid having surfaces that directly face each other. The features may be shaped or positioned to provide a pseudo-random distribution of inclined surfaces across the escape surface, and multiple roughening processes may be used.