Optical Member With Porous Moisture Layer

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Solution Overview

Problem

Existing optical elements with antireflection coatings and water-absorbent layers face issues with moisture retention, leading to degradation of antifogging properties over time due to limited moisture release, which increases manufacturing time and cost when hole density is increased to address this.

Innovation Solution

An optical member comprising a substrate, a porous moisture-retaining layer, and a multilayered antireflection layer with a refractive index ratio of 0.85 to 0.95, where the highest refractive index layer is formed using a vapor deposition process, allowing for efficient moisture permeability and retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If holes are formed in the antireflection coating to facilitate moisture release, then antifogging properties are improved, but manufacturing time and cost increase

Engineering Contradiction:

Improveantifogging propertiesVSAvoidmanufacturing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts the moisture release function from the antireflection coating by introducing a separate porous polymer layer. This layer contains capillaries that actively draw moisture away from the optical element surface, enabling moisture release without modifying the antireflection coating structure or increasing hole density in it.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The porous polymer layer acts as an intermediary between the optical element and the external environment for moisture management. It provides a dedicated moisture transport pathway through capillary action, mediating the moisture release process without requiring modifications to the antireflection coating layers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If holes are formed in the antireflection coating to facilitate moisture release, then antifogging properties are improved, but manufacturing cost increases

Engineering Contradiction:

Improveantifogging propertiesVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The porous polymer layer serves as a cost-effective, simple structure that provides the moisture release function. Rather than using complex laser drilling or high-density hole patterns in the expensive multilayer antireflection coating, the patent employs a straightforward porous polymer layer that is easier and cheaper to manufacture.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If the absorbent layer retains moisture, then antifogging properties are maintained initially, but the optical element can no longer maintain antifogging properties after repeated exposure

Engineering Contradiction:

Improveantifogging propertiesVSAvoidduration of antifogging properties

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent ensures continuous moisture release by providing an open capillary network in the porous polymer layer that extends to the external environment. This continuous pathway allows absorbed moisture to be continuously drawn away from the optical element surface and released externally, maintaining antifogging properties over repeated exposure cycles.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent employs a porous polymer layer with capillaries that provide continuous pathways for moisture transport. The porous structure enables sustained moisture absorption and release cycles, allowing the optical element to maintain antifogging properties through repeated exposure by continuously evacuating absorbed moisture through the capillary network.

Inventive Principle:

Principle #31Porous materials

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 maintains excellent antifogging and antireflection properties over a wide humidity range, reducing manufacturing costs and time by enabling effective moisture management within the optical member.

Implementation Method 1

a layer having the highest refractive index among layers included in the antireflection layer is formed by a vapor deposition process

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Implementation Method 2

a porous layer... in which a ratio n/n0 is 0.85 or more and 0.95 or less

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS11531142B2Optical member and method for manufacturing optical member

Publication Date: 2022.12.20 CANON KK

AI summary

An optical member that has excellent antireflection properties and that can maintain antifogging properties over a long term, and a method for manufacturing an optical member are provided. The optical member includes, in sequence, a substrate, a porous layer, and a multilayered antireflection layer. The ratio n/n0 is 0.85 or more and 0.95 or less, where n represents a refractive index of a layer having the highest refractive index among layers included in the antireflection layer and n0 represents a refractive index of a compound constituting the layer having the highest refractive index at a theoretical density.