Glass Thin-Film Stack With Contact Layer for Uniform Enamel Firing

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Solution Overview

Problem

Existing thin-film stacks on glass sheets exhibit narrow firing temperature ranges (ΔT) due to interactions with enamel layers, leading to industrial challenges in achieving uniform visual appearance and color homogeneity, particularly when low-emissivity layers are present, requiring precise and costly heating equipment.

Innovation Solution

Incorporating a contact layer, such as silicon oxide, between the thin-film stack and the enamel layer to increase the firing temperature range (ΔT), ensuring uniform heating and reducing color heterogeneities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a thin-film stack is deposited directly on glass sheet, then the structure is simple and production cost is low, but the firing temperature range (ΔT) becomes narrow leading to color heterogeneity

Engineering Contradiction:
Improvecolor homogeneityVSAvoidstack structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

A contact layer is introduced as an intermediary between the thin-film stack and the enamel layer. This contact layer acts as a mediator that improves thermal coupling during firing, thereby expanding the firing temperature range (ΔT) and ensuring uniform color appearance without requiring complex heating equipment

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If high-performance heating equipment is used to achieve uniform color, then color homogeneity is improved, but production cost increases

Engineering Contradiction:
Improvecolor homogeneityVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention changes the thermal parameters of the coating structure by introducing a contact layer with specific thermal properties. This modification expands the firing temperature range (ΔT), allowing standard heating equipment to achieve uniform color homogeneity without requiring expensive high-performance heating systems

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If enamel layer is deposited directly on thin-film stack, then the process is simple, but visual appearance becomes sensitive to firing temperature variations

Engineering Contradiction:
Improvedeposition processVSAvoidvisual appearance stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The contact layer serves as a buffer intermediary between the enamel layer and the thin-film stack. It decouples the enamel layer from direct thermal interaction with the thin-film stack, making the visual appearance less sensitive to firing temperature variations and improving production reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

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 contact layer enhances the firing temperature range, allowing for more uniform visual appearance and reduced industrial production costs by improving color homogeneity and reducing the need for precise heating equipment.

Implementation Method 1

the deposition, on at least part of the surface of said stack, of a layer of enamel... The contact layer enhances the firing temperature range, allowing for more uniform visual appearance

Methodology Applied
Scientific EffectThermal energy absorption and distribution: Conduction (thermal)

Implementation Method 2

under the effect of a heat treatment of firing, softens and adheres to the glass sheet

Methodology Applied
Scientific EffectSoftening and adhesion through heating: Melting

Data Source

PatentEP3810557B1Glass sheet coated with a stack of thin layers and with an enamel layer
Publication Date: 2025.08.13 SAINT GOBAIN VITRAGE SA

AI summary

The invention relates to a material comprising a glass sheet coated, on at least one part of one of the faces thereof, with a stack of thin layers, said stack being coated, on at least one part of the surface thereof, with an enamel layer comprising zinc and at least 5% by weight of bismuth oxide, said stack further comprising, in contact with the enamel layer, a layer, called contact layer, that is based on an oxide, the physical thickness of said contact layer being at least 5 nm.