Antireflection Optical Element with Elastic Moth-Eye Structures
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Solution Overview
Problem
Optical elements with moth-eye structures struggle to effectively remove fingerprints and other stains due to the sinking of stains into concave portions, which reduces the antireflection effect, and existing surface treatments like fluorine coating are insufficient in preventing this issue.
Innovation Solution
The development of optical elements with structures having a modulus of elasticity between 1 MPa and 1,200 MPa, and an aspect ratio of 0.6 to 1.5, arranged in patterns such as tetragonal or hexagonal lattices, where the structures are deformed during wiping to push out adhered stains, and the use of surface treatments like fluorine-based substances to improve the contact angle and prevent stain wetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a moth-eye structure with concave portions is formed on the optical element surface, then the antireflection effect is improved, but stains sink into the concave portions and cannot be removed by dry cloth wiping
Solution Approach 1:
The patent applies a flexible resin layer with elastic properties (modulus of elasticity between 1 MPa and 1,200 MPa) that can deform during wiping to push stains out of concave portions, then recover its original shape. This flexible layer acts as a dynamic barrier that actively expels contaminants rather than passively resisting them, resolving the contradiction between maintaining antireflection through concave structures and enabling effective cleaning.
Solution Approach 2:
The patent specifies precise parameter ranges for the resin layer including modulus of elasticity (1-1,200 MPa), thickness (0.1-10 μm), and aspect ratio of concave portions (0.6-1.5) to optimize both the antireflection performance and the ability to remove stains through deformation during wiping. By controlling these parameters, the structure maintains its optical function while gaining cleaning capability.
2Reliability
If the concave portions are made finer to improve antireflection, then the reflection suppressing effect is enhanced, but the power of stains to remain in the concave portion becomes larger than the power of fiber to soak up stains
Solution Approach 1:
The elastic resin layer provides a mechanical counterforce through deformation that actively pushes stains out of increasingly fine concave portions. As the concave portions become finer for better antireflection, the flexible layer's elastic recovery force becomes stronger relative to the capillary forces holding stains, maintaining cleaning effectiveness despite reduced feature size.
Solution Approach 2:
The patent introduces dynamic deformation of the resin layer during wiping to counteract the increasing stain adhesion in finer structures. The layer deforms under wiping pressure to expel stains, then recovers its shape, creating a dynamic cleaning mechanism that adapts to the scale of the concave portions and maintains effectiveness across different feature sizes.
3Object-affected harmful factors
If fluorine coating is applied to reduce surface energy and prevent stain sinking, then some resistance to staining is achieved, but dry cloth wiping still fills stains into concave portions
Solution Approach 1:
The patent combines fluorine coating for passive stain resistance with an elastic resin layer that provides active stain removal through deformation. The fluorine layer reduces surface energy to prevent initial stain penetration, while the elastic layer's mechanical deformation during wiping actively expels any stains that do enter concave portions, achieving both resistance and ease of cleaning.
Solution Approach 2:
The patent creates a composite structure combining fluorine-coated surfaces with an elastic resin layer having specific mechanical properties. This composite approach integrates the chemical resistance of fluorine coating with the mechanical cleaning action of the elastic layer, achieving superior performance in both stain resistance and ease of cleaning that neither component could achieve alone.
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 proposed solution enables effective removal of fingerprints and other stains while maintaining the antireflection properties by deforming the structures to push out stains and using surface treatments to prevent wetting and spreading, thereby enhancing the optical element's performance.
Implementation Method 1
the modulus of elasticity of the material forming the structures is 1 MPa or more, and 1,200 MPa or less
Implementation Method 2
the structures are deformed during wiping to push out adhered stains
Implementation Method 3
the use of surface treatments like fluorine-based substances to improve the contact angle and prevent stain wetting
Implementation Method 4
the adhered stains are sunk into the concave portions of the structure because of a capillary phenomenon
Data Source
AI summary
An optical element with an antireflection function is provided with a substrate having a surface and a plurality of structures formed from convex portions or concave portions and arranged in large numbers on the surface of the substrate with a minute pitch less than or equal to the wavelength of the visible light, wherein the modulus of elasticity of the material forming the structures is 1 MPa or more, and 1,200 MPa or less, and the aspect ratio of the structure is 0.6 or more, and 1.5 or less.