Luminaire Diffuser Micro-Optical Elements Uniformity
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Solution Overview
Problem
LED luminaires often exhibit non-uniform luminous emittance, leading to spotty or dotted patterns and unpleasant glare effects, which conflicts with the desire for energy-efficient and visually appealing lighting solutions.
Innovation Solution
A diffuser with micro-optical elements, such as faceted optical structures, is used to redirect light in a way that creates a uniform luminous emittance within a specific range of polar angles, compensating for initial non-uniformities by varying the density and size of optical elements across the diffuser's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED light sources are used to reduce energy consumption, then energy efficiency is improved, but the exit window appears spotty and non-uniform
Solution Approach 1:
The patent applies local quality by varying the density and/or size of micro-optical elements across different regions of the diffuser. Specifically, neighborhoods closer to the LED light source have lower density or smaller micro-optical elements, while neighborhoods farther away have higher density or larger elements. This compensates for the non-uniform light distribution from the compact LED, achieving uniform luminous emittance across the exit window while maintaining LED energy efficiency.
2Illumination intensity
If light is reflected back into the luminaire to achieve uniform appearance, then visual uniformity is improved, but optical efficiency decreases
Solution Approach 1:
The patent segments the diffuser into multiple neighborhoods, each with independently optimized micro-optical element characteristics. This allows localized control of light redistribution without requiring global light reflection. The micro-optical elements in each neighborhood redirect light forward into the desired viewing hemisphere, achieving uniformity through controlled transmission rather than reflective feedback, thus avoiding optical losses.
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 a spatially uniform luminous emittance within desired angles, enhancing the visual appeal of LED luminaires while maintaining high optical efficiency by diffusing light without reflecting it back into the luminaire.
Implementation Method 1
Each element is adapted to redirect light into a first range of polar angles... Each micro-optical element comprises at least one facet... the light emerging from each element does so at a predetermined polar angle
Implementation Method 2
Each micro-optical element comprises at least one facet adapted to redirect the light by at least one of: refraction; and total internal reflection
Data Source
Figure 1~2
Figure 3~4
Figure 5~6(c)
AI summary
A luminaire comprising: a light source (10); an exit window (20) for light from the light source; and a diffuser (25; 200a; 200b; 200c; 200d) at the exit window for diffusing the light. The diffuser comprises a plurality of micro-optical elements (203a; 203b; 204, 205; 206, 207). Each micro-optical element is adapted to redirect light from the light source, so that the redirected light from each element emerges from the diffuser at a respective predetermined polar angle (Θ). The plurality of micro-optical elements comprise first micro-optical elements, which redirect light from the light source into a first range of polar angles, wherein the first optical elements occupy a greater proportion of the area of the diffuser in a first neighbourhood than in a second neighbourhood, and wherein the first neighbourhood receives less light from the light source than the second neighbourhood. Also provided is a method of designing and manufacturing a diffuser for such a luminaire.