Windshield Lens Stack Thermoforming With Peel-Off Sacrificial Layer
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Solution Overview
Problem
The installation of flat transparent lenses on a compound curved windshield surface often results in uneven heating, overheating, and scratching due to the lack of even heat and pressure distribution, leading to optical distortion and inadequate adhesion.
Innovation Solution
A method involving a moldable covering with a stack of lenses, an adhesive layer between each pair, and a sacrificial layer on the outermost lens, which is more heat-resistant and less scratch-resistant than the lenses, allowing for even heat and pressure application and subsequent peeling to reveal the lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If heat and pressure are applied directly to the flat film during installation, then the film can be formed to the curved windshield surface, but uneven heating and overheating occur causing optical distortion
Solution Approach 1:
A moldable covering is introduced as an intermediary element between the heat source and the flat film. This covering is formed to match the curved windshield surface, allowing heat to be distributed evenly across the film without direct concentrated heating that causes distortion. The moldable covering acts as a mediator that transforms the heating process from direct and uneven to indirect and uniform.
Solution Approach 2:
The moldable covering is pre-formed to match the curved surface geometry before the actual film installation. This preliminary shaping creates a prepared mold that guides the subsequent heating and forming process, ensuring that when heat is applied, the film conforms to the pre-established curved shape without experiencing uneven thermal distribution.
2Reliability
If pressure is applied with a card or squeegee to adhere the film, then adhesion to the windshield is achieved, but the visible surface is permanently scratched
Solution Approach 1:
The moldable covering serves as a protective intermediary layer between the installation tools (card or squeegee) and the visible surface of the film. Pressure applied during installation is transmitted through this covering, which absorbs the mechanical contact and prevents direct scratching of the film's visible surface, while still achieving adequate adhesion through the pressure distribution.
Solution Approach 2:
The moldable covering is positioned in advance to provide a cushioning protective layer over the film's visible surface. This pre-positioned protection ensures that when installation pressure is applied with tools, the force is distributed through the covering rather than directly impacting the film surface, preventing permanent scratches before they can occur.
3Reliability
If the outermost lens is directly exposed during installation, then the lens can be adhered to the windshield, but the lens surface is susceptible to scratching and damage
Solution Approach 1:
A sacrificial layer is introduced as a disposable protective element that is deliberately less scratch-resistant than the outermost lens. This sacrificial layer is positioned over the lens during installation, absorbing all scratching and mechanical damage. After installation is complete, the sacrificial layer is removed, having served its purpose of protecting the valuable lens surface throughout the installation process.
Solution Approach 2:
The sacrificial layer acts as a temporary intermediary between the installation environment and the outermost lens. It provides a protective barrier that can be scratched and damaged without affecting the lens underneath. This mediator allows the lens to be installed with full adhesion while its surface remains protected from scratching throughout the installation 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
This method ensures even heat and pressure distribution, preventing scratching and distortion, while allowing for efficient adhesion and thermal insulation, and enabling the lenses to be conformed to the windshield shape without damaging the outermost lens.
Implementation Method 1
applying heat and pressure to the moldable covering
Implementation Method 2
an adhesive layer interposed between each pair of adjacent lenses from among the two or more lenses
Data Source
AI summary
A method of installing a stack of two or more lenses on a curved substrate includes placing a moldable covering on a curved substrate, the moldable covering including a stack of two or more lenses, an adhesive layer interposed between each pair of adjacent lenses from among the two or more lenses, and a sacrificial layer disposed on an outermost lens of the stack, the sacrificial layer including a sacrificial lens and a sacrificial adhesive interposed between the sacrificial lens and the outermost lens of the stack. The method may include applying heat and pressure to the sacrificial layer and peeling off the sacrificial layer to reveal the stack of two or more lenses.