Faceted Reflector for Uniform LED Curing
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Solution Overview
Problem
Conventional lighting systems using LEDs for curing photosensitive materials face issues with non-uniform illumination due to hemispherical light emission patterns and retro-reflection at reflector corners, leading to under-curing or over-curing of non-hemispherically shaped target areas.
Innovation Solution
A lighting device with a tapered reflector having corner facets is employed, where the reflector side walls diverge to form openings and corner facets are positioned to reduce retro-reflection, ensuring uniform light distribution and collimation towards the target area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional LEDs with hemispherical emission pattern are used, then the lighting device is simple in structure, but the illumination uniformity over rectangular target areas deteriorates
Solution Approach 1:
The reflector is segmented into multiple planar facets arranged in a polyhedral configuration. Each facet is independently oriented to redirect light toward specific regions of the rectangular target area, transforming the hemispherical emission into a uniform rectangular distribution pattern.
Solution Approach 2:
Different facets of the polyhedral reflector have different orientations and geometries tailored to specific local requirements. Corner facets are specifically designed to address corner illumination deficiencies, while other facets target different regions to achieve overall uniformity across the rectangular surface.
2Device complexity
If conventional reflectors without corner facets are used, then the device complexity is reduced, but corner illumination deteriorates due to retro-reflection
Solution Approach 1:
The reflector structure is segmented to include distinct corner facets separate from the main reflector body. These corner facets are positioned specifically at the corners to intercept and redirect light that would otherwise undergo retro-reflection, ensuring adequate corner illumination.
Solution Approach 2:
The corner facets are strategically positioned to intercept light rays that would otherwise undergo harmful retro-reflection. By capturing these rays and redirecting them toward the target area, the potentially harmful retro-reflected light is converted into useful illumination for corner regions.
3Illumination intensity
If larger coupling optics are used to improve illumination uniformity, then the illumination uniformity improves, but the device size and manufacturing cost increase
Solution Approach 1:
The coupling optics are segmented into multiple discrete planar facets rather than requiring a single large complex optical element. This segmentation allows for simpler manufacturing of individual facets that can be assembled together, reducing overall manufacturing cost while achieving the desired uniform illumination pattern.
Solution Approach 2:
Instead of increasing the size of conventional optics in three dimensions, the solution transitions to a polyhedral structure with multiple two-dimensional facets. This dimensional approach achieves improved illumination uniformity through geometric arrangement rather than through increasing optical element size, thereby controlling manufacturing costs.
4Device complexity
If conventional lighting systems are used, then the setup is simple, but the cure time increases due to non-uniform illumination
Solution Approach 1:
The lighting system uses multiple facets working in parallel to illuminate different regions of the target area simultaneously. This segmented approach ensures that all regions including corners receive adequate light intensity, enabling uniform curing across the entire surface and reducing overall cure time.
Solution Approach 2:
The polyhedral reflector provides locally optimized illumination for different regions of the target area. Corner facets specifically address corner regions that would otherwise be under-illuminated, ensuring that all areas receive sufficient light intensity for proper curing, thereby reducing the time required for complete curing.
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 solution achieves uniform irradiation of photosensitive materials, reduces the size of coupling optics, and decreases the distance between light sources and the work piece, thereby shortening cure times and lowering manufacturing costs.
Implementation Method 1
positioning a tapered reflector between the light emitting element and the work piece, wherein light emitted through the first opening and incident at tapered reflector side walls is collimated through the second opening of the tapered reflector toward the work piece about the central axis
Implementation Method 2
positioning corner facets at corresponding corners of the tapered reflector, wherein light incident at the corner facets is collimated towards the work piece about the central axis
Data Source
AI summary
A lighting device may comprise a light emitting element and a reflector, the reflector comprising: a first opening surrounding the light emitting element and a second opening; reflector side walls forming the first and second openings, the reflector side walls divergently extending from the first opening away from the light emitting element to the second opening; and corner facets, wherein each corner facet is positioned over a corresponding reflector corner formed by an adjacent pair of reflector side walls at the first opening. In this way, a photosensitive work piece may be uniformly irradiated while mitigating under-curing and over-curing, and while reducing a coupling optics size and a distance between the light emitting elements and the work piece, thereby decreasing cure times and lowering manufacturing costs.