Optical Waveguide Luminaire with Deflection Surfaces for Directional Light Extraction
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Solution Overview
Problem
Low-efficiency light coupling in LED-based luminaires due to losses when light is emitted from a Lambertian source into a narrow edge of a waveguide plane, particularly in applications like roadway lighting where directional illumination is desired while minimizing neighboring region illumination.
Innovation Solution
A lighting device with a body of optically transmissive material featuring a light input surface, a light transmission portion, and at least one light deflection surface, along with a light extraction portion comprising multiple surfaces for directional light extraction, utilizing total internal reflection to efficiently direct and extract light from the waveguide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light is emitted from a Lambertian LED source into a narrow edge of a waveguide plane, then the luminaire structure is simple, but light coupling efficiency is low due to losses
Solution Approach 1:
The luminaire is divided into distinct functional modules: a Lambertian LED light source, a light-coupling element with specific geometry, and a waveguide body with extraction features. This segmentation allows each component to be optimized independently for its specific function while maintaining overall system simplicity.
Solution Approach 2:
A light-coupling element is introduced as an intermediary component between the Lambertian LED source and the waveguide edge. This coupling element acts as a mediator that transforms the omnidirectional Lambertian emission into directed light paths that efficiently couple into the waveguide, thereby improving light coupling efficiency without requiring complex luminaire restructuring.
2Illumination intensity
If conventional light extraction methods are used, then the waveguide structure is simple, but directional illumination control is poor and neighboring region illumination cannot be minimized
Solution Approach 1:
The waveguide incorporates localized extraction features (such as prisms, gratings, or textured surfaces) at specific positions and orientations to control light extraction in particular directions. This local modification of the waveguide structure enables precise directional illumination control while minimizing light propagation to neighboring regions, without requiring complete restructuring of the entire waveguide.
Solution Approach 2:
The extraction features are designed with asymmetric geometries and selective orientations that preferentially extract light in desired directions while suppressing extraction in other directions. This asymmetric design provides superior directional illumination control compared to symmetric or uniform extraction structures.
3Illumination intensity
If light is extracted from the waveguide, then illumination is provided, but light distribution uniformity is poor and glare occurs
Solution Approach 1:
The extraction features are designed with specific geometric parameters (angles, dimensions, spacing) that control the angular distribution and intensity of extracted light. By optimizing these parameters, the system achieves uniform light distribution across the target area while limiting light intensity in directions that would cause glare to observers or drivers.
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 uniform and directional illumination patterns suitable for applications like roadway lighting with improved light distribution and reduced glare.
Implementation Method 1
A luminaire utilizes a body of optically transmissive material exhibiting a total internal reflection characteristic
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
Data Source
AI summary
A lighting device comprises a body of optically transmissive material exhibiting a total internal reflection characteristic, the body further comprising a light input surface for receiving light, a light extraction portion spaced from the light input surface, a light transmission portion disposed between the light input surface and the light extraction portion, and at least one light deflection surface for deflecting light toward the light extraction portion. Further in accordance with this aspect the light extraction portion comprises a first extraction surface for extracting light deflected by the at least one light deflection surface out of the body and a second extraction surface for extracting light other than light deflected by the at least one light deflection surface out of the body.