Glass Coating Assessment for Tempering Mark Visibility

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Solution Overview

Problem

There is no straightforward method to predict the influence of coatings on the appearance of toughening marks in heat-strengthened glasses before production, and existing solutions do not effectively address the inhomogeneity and anisotropy in thermal reinforcement processes, leading to inconsistent temper marks.

Innovation Solution

A method is developed to evaluate the sensitivity of glazing to toughening marks by measuring color differences using a parameter σv, which compares areas with and without optical phase shifts, allowing for the simulation of coating effects on thermal reinforcement marks before production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermal strengthening is applied to glass to improve mechanical resistance, then strength is improved, but tempering marks appear due to inhomogeneous stress distribution

Engineering Contradiction:
Improvemechanical resistanceVSAvoidtempering marks
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent applies colorimetric analysis to detect and evaluate tempering marks by measuring color differences (ΔE) in regions with optical phase shifts compared to reference regions. This allows quantitative assessment of the visual impact of tempering marks without changing the mechanical properties of the glass.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent replaces direct mechanical or optical inspection methods with a computational colorimetric approach. By using color difference measurements and automated image processing, the system substitutes traditional visual evaluation with an objective, quantifiable metric system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If coatings are applied to glass to modify appearance or performance, then functional properties are improved, but the influence on tempering marks cannot be predicted before production

Engineering Contradiction:
Improvecoating functionalityVSAvoidpredictability of temper mark appearance
Core Design Contradiction:
Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent enables preliminary evaluation of tempering mark appearance by calculating color difference metrics before actual production. The method allows manufacturers to predict how different coating configurations will affect the visibility of tempering marks, enabling informed decisions before committing to production runs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a virtual model of the coated glass appearance by simulating optical phase shifts and calculating resulting color differences. This computational copy allows evaluation of multiple coating scenarios without physical prototyping.

Inventive Principle:
Principle #26Copying

3Difficulty of detecting and measuring

If manual inspection of temper marks is performed to assess quality, then detection capability is maintained, but efficiency and objectivity are reduced

Engineering Contradiction:
Improvetemper mark detectionVSAvoidinspection efficiency
Core Design Contradiction:
Difficulty of detecting and measuringVSProductivity

Solution Approach 1:

The patent replaces manual visual inspection with an automated computer-based system that captures images, processes them through colorimetric analysis, and objectively quantifies tempering marks. This substitution dramatically improves both efficiency and objectivity by eliminating human subjectivity and enabling rapid processing of multiple samples.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-evaluation by automatically capturing images, calculating color differences, and generating quality assessments without requiring manual intervention. The computational algorithm independently evaluates tempering mark severity based on predetermined color difference thresholds.

Inventive Principle:
Principle #25Self-service

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 enables the prediction of how coatings will affect toughening marks, reducing or increasing their visibility, and helps in choosing the most suitable coating system to minimize temper marks by comparing σv values for coated and uncoated glass substrates.

Implementation Method 1

areas with different stresses cause different optical phase shifts in light rays, thus giving them different colors

Methodology Applied
Scientific EffectOptical phase shift: Photoelasticity

Implementation Method 2

due to the photoelastic properties of glass, this can manifest, under polarized light, as iridescence well known to professionals as 'quench marks' or 'strain patterns'

Methodology Applied
Scientific EffectPhotoelastic properties: Photoelasticity

Implementation Method 3

A coating applied to glass can alter the appearance of its temper marks, either increasing or decreasing them

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP3722265B1Method for assessing the sensitivity of a glass panel to forming quench marks
Publication Date: 2023.07.19 SAINT GOBAIN VITRAGE SA
  • EP3722265B1 patent drawingFigure 1~2
  • EP3722265B1 patent drawingFigure 3~4
  • EP3722265B1 patent drawingFigure 5~6

AI summary

The invention relates to a method for evaluating the sensitivity of a glazing to form tempering marks as a function of its anisotropy, said sensitivity being evaluated by the calculation of a parameter σv, said tempering marks resulting from different optical phase shifts in different areas of the glazing for vision in transmission or in reflection and on one side or the other of the glazing, said method comprising - a calculation step, implemented by computer, of at least one transmission parameter through face 1 or through face 2, called T1 or T2, or of at least one reflection parameter on face 1 or on face 2, called R1 and R2, this calculation being carried out for an area of ​​the glazing without optical phase shift and for an area of ​​the glazing causing an optical phase shift δ;- a calculation step, implemented by computer, of at least one parameter ΔE(δ) corresponding to the color difference between the area of ​​the glazing not causing optical phase shift and the area of ​​the glazing causing optical phase shift δ, from at least one of the parameters T1, T2, R1, R2, then - the calculation of σv by application of a function G depending on the calculated ΔE(δ) and where applicable the corresponding δ(s).