Waveguide Body Coupling Portion for Low-Profile Luminaire Light Extraction
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Solution Overview
Problem
Low-efficiency light coupling from LED sources into waveguides in low-profile LED-based luminaires due to inherent losses in directing light into the narrow edge of a waveguide plane, particularly for lambertian emitting sources.
Innovation Solution
A luminaire design featuring a waveguide body with a central section and side sections, incorporating a coupling portion and light extraction features, where LEDs are positioned adjacent to the coupling portion to direct light into the waveguide, and structural members support the waveguide and power circuit, with tapered side sections and textured surfaces to enhance light extraction and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If light is directed into the narrow edge of a waveguide plane from lambertian LED sources, then the waveguide can be made low-profile, but light coupling efficiency is reduced due to inherent losses
Solution Approach 1:
The patent changes the geometric parameters of the waveguide, specifically transitioning from a narrow edge-entry design to a broader face-entry design. This parameter change allows for improved light coupling efficiency by providing a larger coupling area while maintaining a low overall profile through optimized thickness and extraction feature geometry.
Solution Approach 2:
The patent transitions from coupling light into the waveguide at a narrow edge (one-dimensional entry) to coupling light into a broader face (two-dimensional entry). This dimensional change increases the coupling area and improves efficiency while the waveguide maintains a low profile through optimized thickness in the third dimension.
2Weight of stationary object
If the waveguide size is reduced to lower luminaire costs and weight, then manufacturing costs decrease, but light extraction uniformity becomes more difficult to achieve
Solution Approach 1:
The patent applies local quality by incorporating extraction features at specific locations and orientations on the waveguide surfaces. These features are strategically placed to ensure uniform light extraction across the reduced-size waveguide, with different extraction characteristics applied to different surfaces (top, bottom, side walls) based on local requirements.
Solution Approach 2:
The patent segments the waveguide into distinct surfaces (top surface, bottom surface, side walls) with independently optimized extraction features. This segmentation allows for precise control of light extraction at each surface, achieving uniform overall illumination despite the reduced total size of the waveguide.
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 and uniformity by controlling the angular and spatial distribution of light, achieving desired illumination patterns with reduced waveguide size and weight, and lower luminaire costs.
Implementation Method 1
An optical waveguide mixes and directs light emitted by one or more light sources
Implementation Method 2
Light may be coupled into the waveguide through an air gap and a coupling cavity defined by surfaces located at an edge and/or interior portions of the waveguide. Such surfaces comprise an interface between the relatively low index of refraction of air and the relatively high index of refraction of the waveguide material
Data Source
AI summary
According to one aspect, a luminaire comprises a waveguide body including a central section and first and second separate side sections extending away from the central section along first and second opposed directions, respectively. The central section includes a coupling portion and the waveguide body has a length and includes a plurality of light extraction features that extract light out of the side sections. At least one LED is disposed adjacent the coupling portion and is operated by a power circuit to produce light that is directed into the waveguide body by the coupling portion. At least one structural member extends along the length of the waveguide body for supporting the waveguide body and encloses at least one of the power circuit and the at least one LED.