Circular LED Illumination Lens for Uniform Wide-Angle Close Targets
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Solution Overview
Problem
Existing LED illumination systems face challenges in achieving uniform wide-angle lighting for close targets due to the punctate nature of LEDs, leading to inefficiencies and caustic regions, especially in applications like direct-view LCDs and refrigerator cabinets, where traditional fluorescent lighting is inadequate.
Innovation Solution
The development of circularly symmetric illumination lenses with specific fall-off patterns that allow a smaller number of LEDs to produce uniform illumination across a rectangle, utilizing photometric nonimaging optics to design surface profiles that compensate for volume scattering and Fresnel reflections, ensuring caustic-free illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional fluorescent tubes are used for illumination, then wide-angle coverage is achieved, but uniformity of illumination and energy efficiency deteriorate
Solution Approach 1:
The patent segments the illumination task by using multiple small LED light sources arranged in arrays rather than single fluorescent tubes. Each LED is paired with its own illumination lens, creating modular illumination units that collectively achieve uniform wide-angle coverage while improving energy efficiency through targeted illumination.
Solution Approach 2:
The patent changes the illumination parameters by using LEDs with specific luminous intensity distributions combined with illumination lenses that have optimized surface profiles. This creates controllable beam patterns that spread light uniformly over wide angles, transforming the illumination characteristics from the omnidirectional pattern of fluorescent tubes to directed, uniform distributions.
2Loss of energy
If the number of LEDs is reduced to save power, then energy consumption decreases, but uniformity of illumination and coverage deteriorate
Solution Approach 1:
The patent optimizes the luminous intensity distribution parameters of individual LEDs and combines them with illumination lenses having specific optical parameters. This allows each LED to produce a tailored beam pattern that, when combined with neighbors, achieves uniform illumination with fewer total LEDs, reducing power consumption while maintaining uniformity.
Solution Approach 2:
The patent employs iterative optimization methods where the illumination pattern is analyzed and used to refine the design of subsequent illumination lenses. This feedback loop allows the system to achieve uniform illumination with minimal LEDs by continuously optimizing the optical parameters based on the actual illumination distribution.
3Quantity of substance
If free-form illumination lenses with rectangular patterns are used, then fewer LEDs are needed, but manufacturing precision and figural accuracy deteriorate
Solution Approach 1:
The patent employs illumination lenses with rotationally symmetric (circularly symmetric) surface profiles instead of complex free-form rectangular patterns. This spherical symmetry simplifies manufacturing through rotation molding while achieving the desired illumination distribution, as the symmetric geometry is easier to manufacture with high precision than asymmetric free-form surfaces.
Solution Approach 2:
The patent transforms the illumination approach by changing from rectangular pattern lenses to circularly symmetric lenses with optimized surface profiles. This parameter change in the lens geometry allows fewer LEDs to be used while maintaining manufacturing feasibility and achieving caustic-free uniform illumination through properly optimized optical parameters.
4Volume of moving object
If illumination lenses are made smaller to reduce device size, then compactness improves, but manufacturing precision and optical performance deteriorate
Solution Approach 1:
The patent optimizes the optical parameters of compact illumination lenses, including refractive index, surface curvature radii, and thickness distributions. These parameter optimizations allow small lenses to achieve the desired illumination patterns without requiring excessive manufacturing precision, as the optimized parameters provide tolerance to geometric variations.
Solution Approach 2:
The patent uses rotationally symmetric lens designs with carefully optimized curved surfaces rather than complex free-form geometries. This spherical symmetry simplifies manufacturing while maintaining optical performance in compact form factors, as rotational molding can accurately reproduce symmetric curved surfaces even at small scales.
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 enables efficient, uniform illumination with fewer LEDs, reducing power consumption and lens size, while maintaining high illuminance and compactness, effectively addressing the limitations of prior art in achieving uniformity and reducing manufacturing costs.
Implementation Method 1
an illumination lens positioned over said light emitting diode
Implementation Method 2
design surface profiles that compensate for volume scattering
Implementation Method 3
compensate for volume scattering and Fresnel reflections
Data Source
AI summary
A circular LED illumination lens for short throw lighting, for example, as part of a set of such devices installed on mullions in reach-in refrigerator cabinets, to uniformly light access across the rectangular door and shelves. The lens has an upper surface with a cavity for the LED, an upper surface the shape of a toroid, generated by an elliptical arc, that serves to magnify the light rays from the LED in an outboard direction, and the minor axis tilted about 17 degrees relatives the center axis of the LED which serves to direct the rays at the center of the shelves. The upper surface also preferably includes a spherical dimple to direct light away from the center axis.