Optical Waveguide Varying Coupling Cavities for LED Light Extraction
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Solution Overview
Problem
Low-efficiency light coupling in LED-based luminaires due to losses when Lambertian emitting sources are directed into the narrow edge of a waveguide plane, particularly in applications like roadway lighting where targeted illumination is desired while minimizing neighboring regions.
Innovation Solution
An optical waveguide with varying coupling cavity dimensions and orthogonal x- and y-dimensions, featuring light extraction members that extend along the x-dimension and bisect those extending in the y-dimension, allowing controlled light extraction and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Lambertian emitting LED sources are directed into the narrow edge of a waveguide plane, then light coupling is achieved, but light coupling efficiency is low due to losses
Solution Approach 1:
The patent transitions from edge-lit configuration to face-lit configuration, changing the dimension of light coupling from the narrow edge (1D constraint) to the broad face (2D area), thereby significantly improving light coupling efficiency while maintaining manufacturing feasibility
Solution Approach 2:
The patent modifies the coupling geometry parameters by changing from edge coupling to face coupling, and implements varying coupling cavity dimensions (length, width, depth) to optimize light extraction efficiency at different positions along the waveguide
2Illumination intensity
If light is directed into the narrow edge of the waveguide, then illumination is provided, but neighboring regions are not adequately minimized
Solution Approach 1:
The patent implements position-dependent coupling cavity dimensions along the waveguide face, where cavities at different locations have different sizes and shapes to locally optimize light extraction and directional control, achieving targeted illumination while minimizing spill to neighboring regions
Solution Approach 2:
The waveguide face is divided into multiple coupling cavities that can be independently optimized, allowing different regions to provide different illumination patterns and directions, thereby achieving precise spatial control over light distribution
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
Enhances light extraction efficiency and directional control, achieving a wider illumination pattern in the x-dimension while minimizing illumination in the y-dimension, thus addressing the inefficiencies in existing LED-based luminaires.
Implementation Method 1
Discrete coupling optics use refraction, total internal reflection, and surface or volume scattering to control the distribution of light injected into the waveguide
Implementation Method 2
Discrete coupling optics use refraction, total internal reflection, and surface or volume scattering to control the distribution of light injected into the waveguide
Implementation Method 3
In accordance with well-known principles of total internal reflectance, light traveling through a waveguide is reflected back into the waveguide from an outer surface thereof
Data Source
AI summary
According to one aspect, an optical waveguide comprises a plurality of coupling cavities for directing light into a waveguide body spaced from a particular point. Further, each of the coupling cavities comprises a dimension that varies with distance from the particular point.