LED Lens System Uniform Light Distribution
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Solution Overview
Problem
White LEDs produce light with uneven intensity distribution and a yellowish tint at the peripheral edges, making them inefficient for focused lighting applications.
Innovation Solution
An optical device with a body made of a light-transmitting material, featuring a cavity with cylindrical or conical sidewalls and a flat base, a tapered rear surface for internal reflection, and a lens portion with a convex center and concentric ridges forming a Fresnel lens, which refracts and reflects light to create a uniform intensity distribution and blend yellow light into the center, reducing the yellow tint at the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple collimator with tapered side surfaces is used to direct light from LED, then the device complexity is reduced, but the light intensity distribution becomes uneven
Solution Approach 1:
The collimator body is segmented into multiple functional zones: a cavity portion with cylindrical/conical sidewalls for initial light collection, a tapered surface for internal reflection, and an outer surface with lens portion and flat portions for beam shaping. Each zone performs a specific optical function to achieve uniform light distribution while maintaining structural integration.
Solution Approach 2:
Different portions of the collimator have different optical properties: the cavity sidewalls are cylindrical or conical for light collection, the tapered surface provides internal reflection, the lens portion refracts light for focusing, and the flat portions transmit light without significant refraction. This local differentiation of optical characteristics enables uniform light intensity distribution across the beam.
2Use of energy by moving object
If white LED is used to provide efficient lighting, then energy efficiency is improved, but the light produces yellowish tint at peripheral edges
Solution Approach 1:
The yellowish light from LED peripheral edges, which would normally be harmful, is redirected by the tapered internal reflection surface back toward the center of the light pattern. This converts the harmful peripheral yellow light into a beneficial contribution to the central beam, eliminating the yellowish tint at edges while maintaining energy efficiency.
Solution Approach 2:
The tapered surface acts as an intermediary element that intercepts light from the LED cavity sidewalls and redirects it through internal reflection toward the center. This intermediary surface transforms the problematic peripheral light into a useful component of the central beam, resolving the color uniformity issue.
3Illumination intensity
If a thick collimator body is used to achieve proper light distribution, then the optical performance is improved, but the manufacturing cost and imperfections increase
Solution Approach 1:
The collimator design transitions from a traditionally thick, three-dimensional form to a thin, dish-like cross-section. This dimensional change allows the optical functions to be achieved within a compact thickness by utilizing the full range of surface geometries (cylindrical, conical, tapered, lens, and flat portions) in a radially arranged configuration.
Solution Approach 2:
The collimator employs multiple curved and tapered surfaces including cylindrical/conical cavity sidewalls, a tapered internal reflection surface, and a lens portion with convex center and Fresnel ridges. These curved geometries enable efficient light manipulation within a thin profile, achieving proper light distribution without requiring significant thickness.
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 device achieves a uniform light intensity distribution and color across the light pattern, reducing manufacturing costs and imperfections, and effectively directing light to provide a more efficient and focused beam.
Implementation Method 1
The tapered surface is configured such that light incident upon the tapered surface from the cylindrical sidewall of the cavity is reflected internally
Implementation Method 2
Light from white LED 17 incident upon cylindrical sidewall 15 refracts from the tapered side surfaces 13
Implementation Method 3
a plurality of concentric ridges forming a Fresnel lens portion
Data Source
AI summary
An optical device for distributing light produced by a white LED or other light-producing device includes a lens portion that refracts the light to provide a desired light intensity distribution, and a collimating portion that internally reflects light from the white LED. The optical device may be molded from an acrylic polymer material or the like. The reduced thickness of the device facilitates low cycle times and reduces warpage or other distortion that would otherwise be generated during the molding process.