Backlit Waveguide Luminaire for Uniform Light Distribution
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Solution Overview
Problem
Low-profile LED-based luminaires face efficiency issues due to losses when coupling light from Lambertian emitting sources into narrow waveguide edges, leading to non-uniform light distribution and color temperature variations.
Innovation Solution
A 'back-lit' approach with LED elements located within bores in the waveguide body, using coupling cavities with light extraction features and reflective elements to efficiently direct and mix light, minimizing bounces off absorbing surfaces and allowing for scalable design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If light is coupled from Lambertian emitting LED sources into narrow waveguide edges, then the luminaire structure can be compact, but light coupling efficiency is reduced due to losses
Solution Approach 1:
Instead of coupling light from the edge of the waveguide as in conventional designs, this patent positions LED sources at the back face of the waveguide and couples light through the bulk material. This inverted coupling approach eliminates the narrow edge coupling problem while maintaining compact profile, achieving high coupling efficiency without sacrificing space savings.
Solution Approach 2:
The patent transitions from traditional edge-coupling (2D surface interaction) to bulk-coupling (3D volume interaction) by introducing cavities that extend through the waveguide thickness. This dimensional change allows light to propagate through the waveguide body rather than along the edge, significantly improving coupling efficiency while maintaining the compact form factor.
2Volume of moving object
If conventional edge-coupling is used to maintain compact profile, then the luminaire remains small, but light distribution becomes non-uniform
Solution Approach 1:
By inverting the coupling approach from edge-to-face and bulk-coupling, the patent achieves uniform light distribution throughout the waveguide. The light propagates through the entire bulk material rather than concentrating at the edge, eliminating hot spots and ensuring homogeneous illumination across the luminaire output.
3Device complexity
If conventional edge-coupling is used, then the structure remains simple, but color temperature variations occur due to inefficient light transfer
Solution Approach 1:
The inverted bulk-coupling approach ensures consistent color temperature by enabling efficient and uniform light transfer throughout the waveguide material. All regions of the waveguide receive comparable light input, preventing the color temperature variations that occur in edge-coupled designs where light intensity and spectral composition vary spatially.
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 enhances light coupling efficiency, achieves uniform light and color distribution, and reduces the need for costly heat sinking elements, resulting in high efficacy and improved color rendition.
Implementation Method 1
An LED component is associated with the waveguide so as to emit light into the at least one cavity
Implementation Method 2
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
Implementation Method 3
Discrete coupling optics use refraction, total internal reflection (TIR), and surface or volume scattering to control the distribution of light injected into the waveguide
Implementation Method 4
Discrete coupling optics use refraction, total internal reflection (TIR), and surface or volume scattering to control the distribution of light injected into the waveguide
Implementation Method 5
Discrete coupling optics use refraction, total internal reflection (TIR), and surface or volume scattering to control the distribution of light injected into the waveguide
Data Source
Figure 1~2
Figure 3~4
Figure 3A~6
AI summary
A luminaire having a waveguide suspended beneath a mounting element, the waveguide has a first surface proximal to the mounting element, a second surface distal to the mounting element, and an edge between the first and the second surfaces. At least one cavity extends into the waveguide from the first surface to the second surface. A LED component is coupled to the waveguide so as to emit light into the cavity. LED support structures are also disclosed.