Concave Reflector Curve Design for Uniform LED Beam
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Solution Overview
Problem
Existing reflectors and reflector/LED combinations fail to produce a uniform beam of light, often resulting in hot spots and varying intensity across the beam, which affects the efficiency and application of lighting systems.
Innovation Solution
A concave reflector with a specific reflective curve that matches the radiation pattern of the LED, featuring a critical radius where the curvature becomes sharper, reducing the central hot spot and ensuring that reflected and unreflected light components form coinciding beams of essentially the same size, thereby achieving a more uniform beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional reflector is used to collect and shape light into a beam, then light concentration is achieved, but the beam exhibits non-uniform intensity distribution with hot spots
Solution Approach 1:
The reflector surface is designed with varying local properties - specifically, the slope angle changes continuously from the center to the rim. The central region has shallower slopes while the outer regions have steeper slopes, creating different reflection characteristics in different zones. This local variation in surface geometry redistributes the reflected light to achieve uniform intensity across the beam while eliminating hot spots.
Solution Approach 2:
The reflector employs a continuous change in the slope angle parameter across its surface. By mathematically optimizing the slope angle as a function of radial position, the design transforms the non-uniform light distribution from conventional reflectors into a uniform beam. The slope angle parameter is specifically adjusted to compensate for the LED's inherent radiation pattern and achieve equal intensity distribution.
2Productivity
If the reflector depth is increased to improve beam shaping, then light concentration improves, but manufacturing complexity and cost increase
Solution Approach 1:
The reflector surface is designed as a surface of revolution with a specific curved profile rather than a simple paraboloid or ellipsoid. The curvature is continuously optimized to achieve uniform beam intensity, creating a mathematically defined surface that balances light concentration efficiency with manufacturability. This curved surface design maintains reasonable depth while achieving superior beam uniformity compared to conventional spherical or parabolic reflectors.
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 results in a beam with intensity uniformity across all directions, with at least 70% of the maximum intensity in all directions within the beam, reducing hot spots and improving the overall light distribution in applications such as work lights, desk lamps, and flashlights.
Implementation Method 1
a concave reflector with a specific reflective curve that matches the radiation pattern of the LED
Data Source
AI summary
A concave reflector can form a more uniform beam of light. The light source can be an LED with a nominally lambertian radiation pattern. LED can be high power requiring heatsink. Light reflected by reflector and light exiting without hitting reflector can form coinciding beams of essentially same size. Matching of sizes of reflected and unreflected components can be achieved in part by having a tangent at a rim parallel to axis of reflector. For some LEDs hot spot in center of beam is reduced by curvature becoming increasingly sharp when approaching along reflective curve a critical radius at which tangent to reflector curve in plane containing axis of reflector has angle near 45 degrees with respect to axis of reflector. Reflector can be used in, for example, work lights, desk lamps, accent lights, headlamps, and flashlights. Lamps can have multiple reflectors with one LED for each reflector.