Light Transmitting Member With Porous Silica and Hydrophilic Polymer Coating
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Solution Overview
Problem
Existing light transmitting members, such as those used in image pickup devices, suffer from fogging due to water droplets and contamination, leading to image degradation and poor visibility, especially in wet environments, and existing antifogging properties degrade over time.
Innovation Solution
A light transmitting member with a porous layer containing silicon oxide particles and a hydrophilic polymer layer with zwitterionic groups, where the ratio of hydrophilic polymer to silicon elements within 10 nm of the surface is controlled between 0.15 and 0.40, enhancing antifogging and reflection-suppressing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophilic film is formed on the base material to improve antifogging property, then water droplet adhesion is reduced, but the antifogging property is gradually degraded through contamination with organic matter during long-term use
Solution Approach 1:
The patent applies a porous layer containing silicon oxide particles with controlled pore size and distribution. The porous structure provides hydrophilicity through capillary action while the inorganic material resists organic contamination. The specific surface area and pore volume are optimized to maintain antifogging performance over time without degrading from organic matter accumulation.
Solution Approach 2:
The patent combines multiple materials in a layered functional film: a porous silicon oxide layer for hydrophilicity and contamination resistance, and a hydrophilic polymer-containing layer with zwitterionic groups for enhanced antifogging performance. This composite structure synergistically maintains both antifogging property and long-term stability by dividing functions between layers.
2Illumination intensity
If a low-refractive index layer containing hollow silica fine particles is formed to suppress reflection, then optical performance is improved, but the surface becomes more susceptible to fogging from water droplet adhesion
Solution Approach 1:
The patent applies different functional properties to different layers: the porous silicon oxide layer provides hydrophilicity and water droplet management, while the hydrophilic polymer-containing layer with zwitterionic groups provides enhanced antifogging performance. This local differentiation allows simultaneous achievement of reflection suppression and fogging prevention.
Solution Approach 2:
The patent optimizes the refractive index, pore size, and composition ratios of the functional film layers to achieve both reflection suppression and antifogging performance. By carefully controlling the optical parameters and physical-chemical properties of each layer, the patent resolves the contradiction between optical performance and resistance to water droplet adhesion.
3Reliability
If the hydrophilic polymer content is increased to enhance antifogging property, then water droplet adhesion is reduced, but the reflection suppression performance deteriorates
Solution Approach 1:
The patent divides the functional film into separate layers: a porous silicon oxide layer for reflection suppression and a hydrophilic polymer-containing layer for antifogging performance. This segmentation allows each layer to be optimized independently, enabling high hydrophilic polymer content for antifogging without compromising the optical properties of the silicon oxide layer.
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 light transmitting member with high transparency, reduced water contact angle, and resistance to organic contamination, maintaining excellent optical performance even after prolonged use and water washing.
Implementation Method 1
a low-refractive index layer is formed on a light transmissive base material film. The low-refractive index layer contains hollow silica fine particles or porous silica fine particles, to thereby achieve suppression of reflection
Implementation Method 2
a hydrophilic polymer-containing layer containing a hydrophilic polymer having zwitterionic hydrophilic groups provided on the surface of the porous layer opposite to the base material
Data Source
AI summary
Provided is a light transmitting member, which maintains an antifogging property over a long period of time, and is less liable to be contaminated with organic matter, the light transmitting member including, on a base material, a porous layer containing silicon oxide particles and a layer formed of a hydrophilic polymer, wherein a polymer ratio at a depth of 10 nm from a surface of the light transmitting member is 0.15 or more and 0.40 or less.