Antireflective Coating for Plastic Lenses Using Oxide-Fluoride Layers
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Solution Overview
Problem
Existing antireflective coatings on eyeglass lenses reduce reflection at only a single wavelength, imparting a color hue and lacking abrasion resistance, and are costly and unsuitable for plastic lenses due to high temperature requirements and sensitivity to moisture and gases.
Innovation Solution
A method for applying a combination of oxidic and fluoride coatings in a vacuum at lower temperatures, ensuring neutral color transmission, improved hardness, and compatibility with polarized films, using a sequence of deposition layers to reduce reflectance across a broad spectrum without imparting color distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single-wavelength antireflective coating is applied, then reflection at that specific wavelength is minimized, but the lens imparts a color hue and lacks abrasion resistance
Solution Approach 1:
The patent applies a composite antireflective coating system consisting of multiple layers with different materials (oxidic coating and fluoropolymer coating) to achieve both optical performance and mechanical durability. The oxidic layer provides the primary antireflective function through controlled thickness and refractive index, while the fluoropolymer top layer contributes abrasion resistance and hydrophobic properties, creating a synergistic composite structure that addresses both optical and mechanical requirements simultaneously
2Loss of energy
If high-end wide-band antireflective coatings are applied, then reflection across a wider spectrum is reduced, but the cost becomes prohibitive for sunglasses
Solution Approach 1:
The patent segments the antireflective coating into two distinct functional layers: an oxidic coating layer (such as silicon oxide, titanium oxide, or zinc oxide) that provides the primary broadband antireflective effect through its refractive index properties and controlled thickness, and a fluoropolymer top layer that enhances durability and provides additional optical benefits. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall cost-effectiveness compared to monolithic high-end coatings
3Reliability
If traditional high-temperature coating processes are used, then durable antireflective coatings can be applied, but plastic lenses and polarized films are damaged
Solution Approach 1:
The patent fundamentally changes the temperature parameter of the coating process by employing low-temperature deposition and curing methods. Instead of traditional high-temperature thermal processes, the oxidic coating is deposited at temperatures below 100°C through chemical vapor deposition or sol-gel methods, and the fluoropolymer layer is cured at temperatures under 200°C. This parameter change enables the application of durable antireflective coatings on temperature-sensitive plastic lenses and polarized films without causing warping, delamination, or degradation of the lens materials
4Loss of energy
If plastic lenses are coated with traditional antireflective methods, then reflection is reduced, but moisture and gas absorption interferes with consistent coating application
Solution Approach 1:
The patent implements preliminary surface preparation steps before coating application, including plasma treatment or corona discharge to clean and activate the plastic lens surface, removing organic contaminants and creating a more receptive substrate. Additionally, the lens undergoes controlled humidity conditioning and drying procedures prior to coating deposition to stabilize moisture content. These preliminary actions ensure consistent adhesion and uniform coating thickness by eliminating the variable effects of moisture and gas absorption that would otherwise interfere with the coating process
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 provides a cost-effective, durable antireflective coating that maintains image clarity, reduces reflectance across a wide range of wavelengths, and is suitable for plastic lenses, ensuring no color distortion and enhanced scratch resistance.
Implementation Method 1
A method for applying a combination of oxidic and fluoride coatings in a vacuum
Implementation Method 2
one portion of the light is reflected from the surface of the antireflective oxidic coating and another portion of the light is reflected back from the interface between the antireflective oxidic coating and the lens surface. This well-known phenomenon results in destructive interference wherein there are two reflected waves of light, with each one-half wave out of phase with the other
Data Source
AI summary
An improved method is provided for applying an antireflective high contrast coating to a lens, as well as a lens system made with said method. By coating the lenses with a mixture of an oxide and fluoride, the transmission of undesirable visible light wavelengths is reduced, as is the reflection of undesirable light. This combination not only increases perceived sharpness and detail associated with viewing objects through the lenses, but also reduces undesirable reflected glare. Utilization of increased vacuum during the coating process reduces problems of humidity associated with plastic lenses. The combination of oxide and fluoride is controlled to reduce colored tint or hue in the resulting lenses. By imparting little to no color hue to the lenses, the lenses virtually eliminate any undesired color shift associated with prior art lenses.