Waveguide Redirection Features for Uniform LED Light Distribution
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Solution Overview
Problem
Low-efficiency light coupling and non-uniform light distribution in LED-based luminaires due to the use of predominantly Lambertian emitting sources and the edge-lit approach, which results in significant light losses and non-uniform color and intensity output.
Innovation Solution
A waveguide body with a coupling cavity and redirection features made of optically transmissive materials, where the redirection features are integral and configured to redirect light laterally within the body, enhancing light mixing and uniformity by refracting light rays through interfaces with different indices of refraction, and extraction features are strategically placed to control light exit points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the edge-lit approach with Lambertian emitting LED sources is used, then the luminaire structure is simplified, but light coupling efficiency deteriorates and significant light losses occur
Solution Approach 1:
The waveguide body is divided into multiple functional zones: a coupling zone with a coupling cavity for efficient LED light capture, a redistribution zone with redirection features to uniformize light distribution, and an extraction zone with extraction features for controlled light output. This segmentation allows each zone to optimize its function, resolving the contradiction between structural simplicity and coupling efficiency.
Solution Approach 2:
The waveguide body acts as an intermediary component between the LED light source and the final light output. It captures light from the LED in the coupling cavity, redistributes it uniformly through the redirection features, and controls extraction through the extraction features. This intermediary function transforms the non-uniform Lambertian emission into uniform distributed light while minimizing losses.
2Device complexity
If the edge-lit approach with Lambertian emitting LED sources is used, then the luminaire structure is simplified, but light distribution uniformity deteriorates resulting in non-uniform color and intensity output
Solution Approach 1:
Different regions of the waveguide body are given different optical properties and functions. The coupling cavity region is designed to maximize light capture from the LED, the redirection features region is designed to scatter and uniformize light distribution, and the extraction features region is designed to control light output. This local differentiation of functional qualities achieves uniform light distribution while maintaining overall structural simplicity.
Solution Approach 2:
The redirection features redirect light laterally within the waveguide body, adding a lateral dimension to light propagation. This lateral redirection causes light to travel through different paths and exit at multiple locations along the waveguide, transforming the point-source Lambertian emission into a distributed uniform output across the waveguide surface.
3Stability of the object's composition
If redirection features are added to the waveguide body, then light mixing and uniformity are improved, but device complexity increases
Solution Approach 1:
The redirection features are merged into the waveguide body as an integral part rather than separate components. The redirection features, coupling cavity, and extraction features are all formed as single integrated optical elements, reducing assembly complexity and manufacturing steps while achieving the desired light uniformization function.
Solution Approach 2:
The waveguide body serves multiple functions simultaneously: it acts as a light guide, a mixing chamber with redirection features for uniformization, a structural support element, and an optical extraction surface. This multi-functionality consolidates what would otherwise require multiple separate components into a single universal element, achieving uniform light distribution without proportionally increasing complexity.
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 mixing and uniformity, increasing the overall efficiency of light extraction and distribution, resulting in a more uniform color and intensity output while minimizing light losses and maintaining a compact design.
Implementation Method 1
the redirection feature is formed in the at least one optically transmissive material of the body such that the redirection feature is integral with the body and is configured to redirect light traveling through the body laterally within the body
Implementation Method 2
a body made of at least one optically transmissive material exhibiting a total internal reflectance characteristic
Data Source
AI summary
According to one aspect, a waveguide includes a body exhibiting a total internal reflectance characteristic and having a first face and a second face opposite the first face wherein the first and second faces extend along a lateral direction and a coupling cavity adapted to receive a light emitting diode (LED) that is configured to direct light into the body. The body additionally includes an extraction feature disposed on one of the first and second faces and configured to direct light traveling through the body out of at least one of the first and second faces. The body further includes a redirection feature disposed at least in part between the first and second faces and disposed between the coupling cavity and the extraction feature along the lateral direction, and configured to redirect light traveling through the body laterally within the body.