Aspherical Hexagonal Micro Lens Array for Uniform Illuminance
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Solution Overview
Problem
Micro lens arrays face challenges in achieving uniform and efficient illuminance distribution due to interference and moire fringes, which can lead to non-uniform irradiation patterns and peripheral dimming, especially when hexagonal lens elements are arrayed in a honeycomb shape.
Innovation Solution
A micro lens array with a honeycomb structure where hexagonal lens elements are alternately arranged, with their shape and aspherical surface defined by a mathematical expression including terms like AxmynXmYn, allowing control of the Sag and lens shape to match the light receiving surface, thereby adjusting the irradiation pattern and reducing peripheral dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hexagonal lens elements are arrayed in a honeycomb shape, then interference fringes are suppressed and uniformity of illuminance distribution is improved, but the outer shape of irradiation pattern becomes hexagonal causing peripheral dimming and reduced efficiency
Solution Approach 1:
The patent applies asymmetry by modifying the lens element shape from regular hexagon to aspherical hexagon. The aspherical surface introduces asymmetric curvature characteristics that transform the irradiation pattern from a hexagonal shape to a circular shape. This resolves the contradiction by maintaining the honeycomb array structure (which suppresses interference fringes) while changing the optical output shape to match the light receiving element's rectangular or circular surface, thereby eliminating peripheral dimming and improving efficiency.
Solution Approach 2:
The patent employs parameter changes by introducing aspherical coefficients (k1, k2, k3, k4) into the lens surface equation. These parameters allow precise control over the lens surface curvature in different directions (X and Y directions). By adjusting these parameters, the irradiation pattern's shape and size can be optimized to match the light receiving element's geometry, transforming the peripheral dimming problem into an efficient light utilization solution while preserving the uniform illuminance distribution achieved through the honeycomb arrangement.
2Manufacturing precision
If pitch between lens elements is made small, then light uniformity is improved, but interference fringes become obvious and hinder uniformity
Solution Approach 1:
The aspherical surface design introduces asymmetric optical path lengths for light passing through different regions of the lens element. This asymmetric phase distribution disrupts the regular interference patterns that arise from uniform pitch arrangements. The aspherical coefficients (k1, k2, k3, k4) create controlled optical path variations that suppress interference fringes while maintaining the uniformity benefits of close spacing, effectively resolving the contradiction between pitch density and interference.
3Object-generated harmful factors
If pitch between lens elements is made large, then interference fringes are reduced, but light irradiation becomes non-uniform and moire fringes appear
Solution Approach 1:
The patent uses parameter changes through aspherical coefficients to control the optical path difference between adjacent lens elements. By adjusting k1, k2, k3, and k4, the system can compensate for the larger pitch between lens elements, creating more uniform light distribution. The aspherical surface introduces additional optical path variation that fills the gaps created by larger pitch, suppressing moire fringes while maintaining uniformity without requiring the lens elements to be densely packed.
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 configuration achieves a more uniform and efficient illuminance distribution by controlling the aspherical shape of the lens elements, improving light receiving efficiency and suppressing peripheral dimming, and can be adjusted to match various light receiving surface shapes.
Implementation Method 1
a plurality of lens elements are arranged on at least one surface of a planar member
Data Source
AI summary
A micro lens array including a honeycomb structure including columns of the lens elements alternately arrayed, each of the lens elements having a shape of a hexagon in a plan view and being linearly arranged such that sides of the hexagon in a predetermined direction are in contact with each other, wherein a mathematical expression indicating a SAG of the lens element includes a term of AxmynXmYn (m and n are integers except 0), in a case where, when an optical axis of the lens element is an origin, Y is a coordinate in an arrangement direction of the lens elements in the columns of the lens elements, X is a coordinate in an array direction in which the columns of the lens elements are alternately arrayed, and A is a predetermined coefficient.