Antireflection Layer with Si3N4 and SiO2 Films for Optical Member Durability
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Solution Overview
Problem
Conventional optical members with antireflection films are prone to peeling due to environmental changes, such as temperature and climate variations, leading to potential damage and reduced durability.
Innovation Solution
An optical member design featuring a light-transmissive member covered by a hard coat layer and an antireflection layer with alternately stacked high and low refractive index films, where the high refractive index films are made of Si3N4 and low refractive index films are made of SiO2, with a controlled thickness ratio and even number of films to maintain stress balance and improve durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an antireflection film is applied to prevent hard coat film cracking, then protection against ultraviolet damage is improved, but the film may peel off due to temperature and climate changes
Solution Approach 1:
The antireflection film is divided into multiple thin layers (11 to 15 layers) with alternating high and low refractive indices. This segmentation allows each layer to have optimized thickness and material properties, reducing internal stress and preventing peeling while maintaining ultraviolet protection functionality.
Solution Approach 2:
The patent uses composite material structure with alternating high refractive index layers (e.g., TiO2, SiO2, Nb2O5) and low refractive index layers (e.g., SiO2, Al2O3, Ta2O5). This composite structure optimizes both optical performance for ultraviolet protection and mechanical stability for adhesion under temperature and climate variations.
2Reliability
If multiple layers of antireflection film are stacked to achieve high reflectance in ultraviolet range, then ultraviolet protection is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the thickness parameters of each layer within specific ranges (e.g., high refractive index layer: 5-50 nm, low refractive index layer: 10-100 nm) to achieve the desired optical performance. By carefully controlling these parameters, the patent achieves effective ultraviolet protection with a manageable number of layers (11 to 15), balancing performance and manufacturing complexity.
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 enhances durability by preventing peeling and cracking, allowing the optical member to withstand harsh environments, particularly in outdoor conditions, while maintaining low reflectance in the visible range and high reflectance in the ultraviolet range.
Implementation Method 1
an antireflection layer covering the hard coat layer, in which high refractive index films and low refractive index films are alternately stacked
Data Source
AI summary
An optical member includes a light-transmissive member, a hard coat layer covering the light-transmissive member, and an antireflection layer covering the hard coat layer. The antireflection layer is configured such that the high refractive index films and the low refractive index films are alternately stacked. The high refractive index film contains Si3N4. The low refractive index film contains SiO2. The total number of films of the high refractive index films and the low refractive index films is an even number. For each of the high refractive index film and the low refractive index film in the antireflection layer, of two adjacent films, a ratio of thickness of a thick film to thickness of a thin film is six times or less. An average reflectance of the antireflection layer in a wavelength range of 300 to 400 nm is 40% or more.