Low-Reflectance Removable Lens Stack With Mechanical Interlocking
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Solution Overview
Problem
Conventional removable lens stacks with moth-eye coatings experience increased peel strength due to adhesives filling in around the bumps, making it difficult to tear off layers, and result in high reflection, compromising visibility.
Innovation Solution
A removable lens stack design featuring a base layer with a moth-eye coating and additional layers with fluoropolymer coatings molded to fit the moth-eye pattern, eliminating the need for tacky adhesives and reducing peel strength to less than 100 grams per inch, while maintaining high visible light transmission through mechanical interlocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesives are used between lens layers to bond them together, then the layers remain attached, but the peel strength increases to 650-1070 grams/inch making layers difficult to tear off
Solution Approach 1:
The patent removes the adhesive layer entirely from the lens stack structure. Instead of using adhesives to bond layers, the invention relies on mechanical interlocking between the moth-eye coating bumps and corresponding recesses in adjacent layers, eliminating the need for chemical bonding agents that create excessive peel strength.
Solution Approach 2:
The patent introduces a mechanical intermediary structure (the moth-eye coating with bumps and recesses) that mediates the bonding between layers. This physical interlocking mechanism replaces the chemical intermediary (adhesive) and provides controlled attachment strength that allows easy layer removal while maintaining layer integrity.
2Illumination intensity
If moth-eye coatings are applied to reduce reflection, then visible light transmission increases, but adhesives fill in around the bumps increasing peel strength
Solution Approach 1:
The patent extracts the adhesive component from the system and replaces it with a mechanical interlocking mechanism. The moth-eye coating bumps engage with corresponding recesses in adjacent layers through pure mechanical interaction, eliminating the adhesive that would otherwise fill in around the bumps and increase peel strength.
Solution Approach 2:
The patent applies different properties to different parts of the lens stack: the moth-eye coating provides optical properties (anti-reflection) on the surface, while the mechanical interlocking structure provides controlled mechanical properties (peel strength) at the interface. This local differentiation allows each function to optimize independently without compromise.
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 design allows easy removal of layers with minimal force and achieves visible light transmission greater than 95%, reducing reflections and maintaining clarity.
Implementation Method 1
Each of the fluoropolymer coatings may be molded to fit the moth eye coating of the immediately preceding layer
Implementation Method 2
One promising technology for reducing reflection is so-called moth-eye (ME) coatings, which simulate the anti-reflective properties of a moth's eye by providing a pattern of microscopic bumps that effectively eliminate the index of refraction interface between the lens and the air
Data Source
AI summary
A removable lens stack includes a base layer and one or more removable lens layers. The base layer may include a substrate and moth eye coatings on first and second sides of the substrate. A first removable lens layer may include a substrate and an acrylic or fluoropolymer coating on a first side of the substrate and may be stacked on top of the base layer such that the second side of the substrate faces the first side of the substrate of the base layer. A second removable lens layer may include a substrate and an acrylic or fluoropolymer coating on a first side of the substrate and may be stacked on top of the first removable lens layer such that the second side of the substrate faces the first side of the substrate of the first removable lens layer. The acrylic or fluoropolymer coating may comprise a hard coat.