Lighting Device With Parabolic Collimator And Diffuser
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Solution Overview
Problem
Existing illumination devices using small light sources like LEDs struggle to achieve uniform light distribution for general and tailored lighting applications due to poor collimation and non-uniform light patterns caused by the divergent nature of these sources, which are not effectively addressed by current reflective parabolic or catadioptric designs.
Innovation Solution
A lighting device combining wide-angle light sources with collimators and diffusers, where the collimator uses a parabolic body with spherical and hyperbolic surfaces for partial collimation, and a diffuser with a randomized microlens structure to achieve angularly dependent light intensity, providing a uniform illumination pattern over a specified area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective parabolic structure is used to collimate light from a small light source, then the light is redirected parallel to the axis of the parabola forming a narrow beam, but the actual divergence of the reflected beam is determined by the size of the reflector and the finite size of the source, resulting in poor far field quality and ring structure
Solution Approach 1:
The patent divides the optical system into multiple discrete lens elements (first lens element, second lens element, third lens element) arranged in sequence. Each lens element performs a specific function: the first lens collimates light from the source, the second lens further refines the beam, and the third lens corrects aberrations. This segmentation allows each element to be optimized for its specific function, resolving the contradiction between achieving narrow beam collimation and maintaining far field quality.
2Illumination intensity
If a lens element is added at the open end of the reflector to capture direct light from the source, then both direct light and reflected light are captured, but if the lens is made to collimate the direct light then it causes the reflected light to be highly divergent, compromising between divergence and uniformity
Solution Approach 1:
The patent applies local quality by assigning different optical properties to different lens elements in the sequence. The first lens element is designed with specific curvature and refractive index to collimate direct light from the source. The second lens element has different parameters optimized for refining the collimated beam. The third lens element is designed specifically for correcting aberrations and maintaining beam uniformity. Each element's local optical characteristics are tailored to its specific function in the overall light control system.
3Adaptability or versatility
If collimated light from small divergent light sources is passed through a typical general lighting diffuser, then light distribution is attempted, but the collimation causes non-uniform light patterns having undesirable bright spots
Solution Approach 1:
The patent employs asymmetric optical design in the lens elements to correct for the symmetric divergence pattern of the light source. The lens elements have asymmetric curvature profiles and varying refractive indices that are specifically designed to compensate for the non-uniform angular distribution of light from the small divergent source. This asymmetric correction prevents the formation of bright spots and achieves uniform light distribution across the beam.
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 enables efficient use of light from small sources, producing a substantially uniform light distribution suitable for various applications by compensating for non-collimated light portions, allowing for interchangeable diffusers to produce different illumination patterns.
Implementation Method 1
The parabolic outer surface total internally reflects light received via the spherical sides of the cavity toward the light exiting end
Implementation Method 2
The collimator has a parabolic body having a flat light exiting end and a light entering end with a cavity having spherical side surfaces and a center portion having ahyperbolic or ellipsoidal shape
Implementation Method 3
The diffuser has an optical diffusion property providing over an area an angularly dependent output light intensity
Data Source
AI summary
Lighting devices are provided for efficiently distributing light over an area to provided uniform illumination over a wide angle or other tailored illumination patterns. Each light device has at least one light source, at least one collimator for partially collimating light from the light source, and at least one diffuser for diffusing light from the collimator. The diffuser provides diffused light over an area from the diffuser having an intensity that is angularly dependent in accordance with the angular distribution intensity of light outputted from the collimator, so as to provide a predetermined illumination pattern from the device. The light sources and collimators may be provided in one or two-dimensional arrays, and a single diffuser may be formed on each collimator or the diffuser may be along a plate spaced from the collimators.