LED Lighting Module Homogenization via Segmented Lenslets
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Solution Overview
Problem
Existing lighting modules with diffusers enlarge the light source size, both mechanically and optically, complicating the design of secondary optics for specific illumination distributions, especially in narrow-beam applications, and result in annoying shadow lines and coloration in the illumination pattern.
Innovation Solution
A lighting module with an optical structure that provides a substantially constant luminous intensity profile between -α max and +α max, minimizing the light source size while homogenizing the light source, using optical elements like aspherical lenslets with parabolic cross-sections and adjustable maximum deviation angles, and optionally incorporating secondary optical functions for beam shaping and spectral control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a diffuser is used to homogenize the light source, then optical inhomogeneities and shadow lines are prevented, but the light source size is enlarged both mechanically and optically
Solution Approach 1:
The diffuser dome is segmented into multiple discrete optical elements (lenslets) arranged in an array. Each lenslet has a specific deviation angle designed to redirect light from adjacent LED chips, creating overlapping conical emission patterns that homogenize the light source without requiring a large physical dome structure.
Solution Approach 2:
The patent transitions from a single large diffuser dome in the vertical dimension to a two-dimensional array of small lenslets. This dimensional transformation allows the same homogenization function to be achieved with a much smaller overall structure by distributing the optical function across multiple elements in the planar dimension.
2Stability of the object's composition
If the light source size is enlarged to fill dark gaps between LED chips, then a homogeneous virtual light source is created, but the design and use of secondary optics becomes more difficult
Solution Approach 1:
The homogenization function is segmented into multiple small lenslets rather than using a single large optical element. This segmentation creates a compact virtual light source that maintains homogeneity while preserving the small physical footprint needed for simple secondary optics design.
Solution Approach 2:
Each lenslet is designed with a specific maximum deviation angle parameter that determines the cone angle of redirected light. By carefully controlling this parameter, the patent achieves homogeneous illumination without excessive light source enlargement, keeping secondary optics design straightforward.
3Object-generated harmful factors
If a large diffuser dome is used to encompass the LED chip array, then shadow lines are eliminated, but the mechanical size of the light source increases
Solution Approach 1:
The large diffuser dome is replaced by an array of small lenslet elements, each contributing to shadow line elimination through controlled light redirection. This segmentation allows the homogenization function to be achieved with a much smaller mechanical structure.
Solution Approach 2:
Each lenslet is designed with local optical properties (specific deviation angles) tailored to its position in the array. This local optimization ensures that shadow lines are eliminated effectively while maintaining a compact overall structure, as each element contributes precisely to its local illumination zone.
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 effectively minimizes the virtual light source size, maintains a homogeneous illumination distribution, and reduces optical losses, eliminating annoying shadow lines and coloration, while allowing for precise control of light beams and color rendering.
Implementation Method 1
an optical structure which comprises an optical element arranged to provide when observing a light emitting diode through the optical structure with the lighting module in operation, a luminous intensity profile I as a function of a deviation angle α
Data Source
Figure 1~3
Figure 4A~4D
Figure 5A~5B
AI summary
Proposed is a lighting module 100 and an illumination device 200 comprising such a module. The lighting module comprises an array of LEDs 120 mounted on a substrate 110 and an optical structure 130 encompassing the LED array for approximating in operation the LED array as a single homogeneous light source. The optical structure comprises an optical element 140 arranged to provide a luminous intensity profile as a function of a deviation angle a which is substantially constant between -amax and amax, wherein amax is a maximum deviation angle provided by the optical element and substantially zero at angles outside that range. This is especially advantageous for optimizing the trade off between creating a single homogenous light source and maintaining the entendue of the light source. An additional advantage of the optical element 140 is that, except for fresnel reflections on both surfaces, it has no backscattering like a diffuser has, which results in a very low optical loss.