Aviation Glazing with Electrochromic Active Systems
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Solution Overview
Problem
Designing aviation glazing that combines safety features, such as fragment retention, with functional active systems like electrochromic properties is challenging due to reduced adhesion between glass and polymer interlayers, and the need for additional protective substrates, which increases thickness, a critical issue for cockpit windows where space is limited.
Innovation Solution
A triple-glazing configuration with a set-back first substrate and two polymer films for fragment retention, allowing an active system to be positioned on one of the polymer films, ensuring safety and functionality without excessive thickness, using thermally or chemically toughened glass substrates and electrochromic systems for variable optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an active system is inserted into conventional laminated glazing between the glass and the polymer interlayer film, then the glazing gains functional properties (electrochromic, optical valve, liquid-crystal), but the adhesion of the polymer film to the glass is reduced, compromising safety
Solution Approach 1:
The patent divides the glazing structure into distinct segments: outer glass substrate, active system layer, inner glass substrate, and polymer interlayer film. By segmenting the structure so that the active system is positioned on the outer substrate rather than embedded within the lamination, the adhesion between polymer and glass is preserved while functional properties are maintained
Solution Approach 2:
The patent introduces an intermediary arrangement where the active system is positioned on the outer glass substrate, acting as a mediator between the functional requirements and the safety requirements. This positioning allows the polymer interlayer to maintain direct contact with the glass substrates, ensuring adhesion, while the active system provides its functional properties without interfering with the bonding
2Reliability
If an additional protective substrate is added to protect the active system from ambient atmosphere, then the active system is protected from chemical or mechanical degradation, but the glazing thickness increases, which is critical for cockpit windows
Solution Approach 1:
The outer glass substrate serves multiple functions simultaneously: it acts as a structural component of the glazing, provides a support surface for the active system, and functions as a protective barrier against the ambient atmosphere. This multi-functionality eliminates the need for an additional protective substrate, maintaining thinness while ensuring protection
Solution Approach 2:
The patent merges the protective function with the structural outer substrate. Instead of adding a separate protective layer, the outer glass substrate is designed to fulfill both structural and protective roles, combining these functions into a single element that maintains the glazing's thickness constraints
3Reliability
If a triple-glazing configuration with two polymer films is used to ensure fragment retention, then safety is improved, but the glazing thickness increases
Solution Approach 1:
The patent applies local quality by positioning the polymer interlayer film specifically where it is most needed for fragment retention—between the glass substrates—while keeping the active system on the outer substrate. This localized application of the polymer film ensures safety functionality without requiring excessive thickness throughout the entire glazing assembly
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
This configuration reconciles safety, functionality, and dimensional constraints, enabling the integration of active systems in aviation glazing without significantly increasing thickness, ensuring compliance with regulatory standards and maintaining structural integrity.
Implementation Method 1
electrochromic systems, which allow the light and thermal transmission to be modulated
Implementation Method 2
droplets of liquid crystals, especially nematic liquid crystals of positive dielectric anisotropy, being dispersed in said film. When voltage is applied to the film, the liquid crystals are oriented along a preferential axis, thereby permitting vision
Implementation Method 3
polymer-based films in which microdroplets containing particles capable of adopting a preferential direction under the action of an electric field are placed
Data Source
AI summary
Glazing comprising, in succession:a first rigid substrate (S1);a second rigid substrate (S2);a third rigid substrate (S3);at least one “active” system (A) that includes at least one layer and is placed between the substrates (S1 and S2), the first substrate (S1) optionally being set back in relation to the other two substrates (S2, S3); andat least one polymer film having the function of retaining glazing fragments should the glazing break, said film being placed between the substrate (S1) and the substrate (S2) and between the substrate (S2) and the substrate (S3).