LED Luminaire Cover Geometry for Uniform Light Distribution
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Solution Overview
Problem
Luminaires designed for previous generation lighting sources, such as incandescent or fluorescent lighting, exhibit suboptimal optical performance when replaced with solid-state lighting (SSL) elements due to differences in optical characteristics, leading to non-uniform luminous distribution and optical artefacts like dark and bright lines, especially when SSL elements are small relative to the luminaire's diameter.
Innovation Solution
A luminaire housing with a light-transmissive cover featuring rounded corner sections between linear, planar sections, where the inner and outer endpoints of the rounded corners are positioned to ensure that light rays entering the cover do not exit through the rounded corner sections, reducing light divergence and stray light by maintaining light rays within the planar sections, and utilizing a computer-implemented method to design and manufacture the cover with optimized splines and thickness for improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a light-transmissive cover with rounded corner sections is used in luminaires designed for previous generation lighting, then the luminaire housing provides aesthetic appeal and mechanical strength, but optical artefacts such as non-uniform luminous distribution, dark and bright lines, and colour effects occur when SSL elements are installed
Solution Approach 1:
The patent applies local quality by differentiating the optical function of different cover sections. The linear planar sections are optimized for light transmission with minimal deviation, while the rounded corner sections are specifically designed with controlled geometry to limit their optical impact. By making the rounded corners sufficiently small relative to the SSL element size and positioning them away from primary light paths, the cover maintains aesthetic appeal while minimizing optical artefacts in the luminous distribution.
2Use of energy by moving object
If SSL elements are installed in luminaires designed for previous generation lighting, then energy consumption is reduced and lifetime is improved, but optical performance deteriorates due to distinctly different optical characteristics
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the cover to match the optical characteristics of SSL elements. Specifically, the rounded corner sections are designed with dimensions and curvature radii optimized for point-source or line-source SSL elements, rather than the distributed light sources of previous generation lighting. This includes controlling the relative size of rounded corners, their positioning, and their interaction with light rays to achieve uniform luminous distribution suitable for modern LED and other SSL technologies.
3Strength
If the cover is made transparent and waterproof with rounded corners, then aesthetic appearance and mechanical strength are improved, but optical artefacts and light divergence increase
Solution Approach 1:
The patent applies asymmetry by creating an optimized geometric configuration where the rounded corner sections are asymmetrically positioned and sized relative to the overall cover geometry and SSL element placement. This asymmetric design allows the rounded corners to provide aesthetic appeal and mechanical strength while their specific positioning and dimensions minimize their impact on light paths, reducing optical artefacts through careful geometric arrangement rather than symmetry.
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 significantly reduces optical artefacts, enhancing the overall optical performance of the luminaire by ensuring that light rays exit through the appropriate sections, resulting in a more uniform and directed luminous output with reduced boundary-induced divergence.
Implementation Method 1
a plane under critical angle θc at the inner surface at an inner endpoint does not extend through the outer surface of the rounded corner section, such that no ray of light emitted by the at least one solid state lighting element entering the light-transmissive cover via the further inner surface of the further section exits the light-transmissive cover from the outer surface of the rounded corner section
Data Source
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AI summary
A luminaire housing (10) comprises a light chamber (15) at least partially delimited by a light-transmissive cover (30). The light chamber comprises a mounting region for mounting at least one solid state lighting element. The cover comprises at least one rounded corner section (31) in between two further sections (33), wherein the rounded corner section has an inner surface (311) having opposing inner endpoints (103, 105) and an outer surface (313) having opposing outer endpoints (113, 115). Each inner endpoint is positioned relative to the outer endpoint proximal to said inner endpoint such that no ray of light (301, 301') emitted by the at least one solid state lighting element entering the light-transmissive cover via an inner surface (331) of a further section exits the light-transmissive cover from the outer surface of a curved corner section. A luminaire including such a luminaire housing, a design method and a manufacturing method for such a luminaire housing are also disclosed.