Waveguide Luminaire Coupling Optics for Low-Profile LED Efficiency
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Solution Overview
Problem
Low-efficiency light coupling in LED-based luminaires due to losses when light from Lambertian sources is directed into the narrow edge of a waveguide plane, particularly in low-profile designs like edge-lit luminaires, which results in inadequate illumination distribution and efficiency.
Innovation Solution
An optical waveguide with orthogonal x- and y-dimensions, featuring coupling features for directing light, light redirection features for angular control, and extraction features for controlled light emission, including scattering elements to enhance light mixing and distribution, allowing for efficient light transmission and emission patterns tailored for specific applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If light from Lambertian LED sources is directed into the narrow edge of a waveguide plane, then the luminaire achieves a low-profile design, but light coupling efficiency deteriorates due to losses
Solution Approach 1:
The patent introduces a coupling optic as an intermediary element between the LED light source and the waveguide. This coupling optic includes a light redirecting element that captures light from the Lambertian LED and redirects it into the waveguide at appropriate angles, serving as a mediator that transforms the light distribution to improve coupling efficiency while maintaining the low-profile edge-lit design
Solution Approach 2:
The patent modifies the angular distribution parameter of light by using the coupling optic to redirect light at specific angles into the waveguide. By changing the angular parameters of light entry into the waveguide, the system overcomes the inherent inefficiency of direct coupling from Lambertian sources while preserving the low-profile form factor
2Device complexity
If light is directed into the narrow edge of a waveguide, then the luminaire structure is simplified, but illumination distribution becomes inadequate
Solution Approach 1:
The coupling optic acts as an intermediary that shapes and conditions light before it enters the waveguide, ensuring proper angular distribution and spatial uniformity. This mediator element enables adequate illumination distribution without adding complex multi-source arrays or reflective structures, thus maintaining structural simplicity while improving light quality
Solution Approach 2:
The coupling optic performs preliminary action by pre-conditioning the light (redirecting, shaping, and distributing) before it enters the waveguide. This preliminary light conditioning ensures that the waveguide receives optimally prepared light, achieving adequate illumination distribution throughout the luminaire output without requiring complex post-processing structures
3Loss of energy
If a coupling optic with light redirecting element is added to improve light coupling, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the coupling optic and the waveguide into an integrated assembly where the coupling optic is positioned in optical communication with the waveguide's input face. This merging combines multiple functions (light capture, redirection, and coupling) into a unified optical system, improving light extraction efficiency while avoiding the complexity of separate, loosely-coupled components
Solution Approach 2:
The coupling optic serves multiple functions simultaneously: it captures light from the LED, redirects it at appropriate angles, conditions the spatial distribution, and couples it into the waveguide. This multi-functionality consolidates what would otherwise require multiple separate components, improving efficiency 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
The solution achieves improved light distribution and efficiency by maximizing light extraction and mixing within the waveguide, enabling targeted illumination patterns with higher efficacy and reduced glare, suitable for applications like roadway or parking lot lighting.
Implementation Method 1
an optical waveguide which directs light developed by one or more light emitting diode (LED) light sources toward a target surface
Implementation Method 2
a second plurality of light coupling features each for transmitting light developed by at least one of the first plurality of LED light sources into the waveguide along a primary light path
Implementation Method 3
a third plurality of light redirection features each for redirecting light in the waveguide to cause at least a portion of the light developed by an LED to be redirected into a secondary light path transverse to the primary light path
Implementation Method 4
a fourth plurality of light extraction features for directing light in the primary and secondary paths to be directed out of the waveguide
Data Source
AI summary
An optical waveguide comprising orthogonal x- and y-dimensions and developing an illumination distribution pattern comprising orthogonal x- and y-extents, comprising at least one coupling feature for directing light into the waveguide, at least one light redirection feature for redirecting light in an x-y plane within the waveguide, and at least one light extraction feature for extracting light out of the waveguide in an illumination pattern comprising at least one of the x- and y-extents that is offset with respect to the x- and y-dimensions, respectively. Additionally, the optical waveguide comprises optical features on at least first, second, and third sides thereof.