Spectacle Frame Thermography Overlay for Accurate Lens Fitting

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Solution Overview

Problem

Existing methods for determining spectacle frame fitting parameters face challenges in identifying the bottom edge of spectacles, particularly under poor lighting conditions or with rimless frames, leading to inaccurate fitting results.

Innovation Solution

A combined photography and thermography method that includes taking a photograph and a thermogram of the wearer's face with spectacles, identifying the spectacles' contour in the thermogram, and overlaying it onto the photograph to obtain fitting parameters such as the fitting height.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a photograph is taken under poor lighting conditions or with rimless frames, then the fitting parameter determination becomes difficult, but using traditional photography alone cannot provide sufficient contrast to clearly identify the spectacles' bottom edge

Engineering Contradiction:
Improvebottom edge identification accuracyVSAvoidlighting condition
Core Design Contradiction:
Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent combines photography and thermography into a hybrid imaging system. The photograph provides structural information while the thermogram provides thermal contrast information. By merging these two imaging modalities, the system overcomes the limitation of poor visibility in photographs under poor lighting conditions or with rimless frames, enabling accurate bottom edge identification through thermal radiation patterns.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermogram acts as an intermediary that provides thermal infrared radiation information to enhance the visibility of the spectacles' outline. The thermal image serves as a mediator that compensates for the insufficient contrast in the photograph, allowing the system to clearly identify the spectacles' bottom edge even when the photograph alone would fail.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If traditional photography is used to determine fitting parameters, then the method is simple, but the spectacles' outline is barely visible under poor lighting conditions or with rimless frames

Engineering Contradiction:
Improvemethod simplicityVSAvoidspectacles visibility
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system merges photography and thermography into a unified measurement approach. While this increases device complexity compared to simple photography, it dramatically improves reliability by ensuring the spectacles' outline is clearly visible through thermal contrast, eliminating the visibility problems that plague traditional photographic methods under various conditions.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of time

If only photograph is taken, then the imaging process is quick, but the outline of rimless frames or frames under poor lighting is difficult to identify

Engineering Contradiction:
Improveimaging timeVSAvoidoutline identification difficulty
Core Design Contradiction:
Loss of timeVSDifficulty of detecting and measuring

Solution Approach 1:

The hybrid imaging system captures both photograph and thermogram simultaneously or in rapid succession, minimizing additional time investment. The thermographic component provides immediate thermal contrast information that makes outline identification straightforward, eliminating the need for time-consuming manual adjustment or re-shooting that would be required with photography alone under challenging conditions.

Inventive Principle:
Principle #5Merging (Combining)

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

Enhances the visibility of the spectacles' outline, allowing for more accurate determination of fitting parameters by leveraging thermal infrared radiation to improve image clarity and precision.

Implementation Method 1

the thermal infrared radiation, which is emitted by the whole face of the spectacle wearer

Methodology Applied
Scientific EffectThermal infrared radiation: Infrared Radiation

Implementation Method 2

the thermal infrared radiation, which is emitted by the whole face of the spectacle wearer, is blocked in the facial regions that are covered by the spectacles

Methodology Applied
Scientific EffectThermal infrared radiation blocking: Absorption (EM radiation)

Data Source

PatentEP4348343B1A photography and thermography combining method of obtaining a fitting parameter to fit an ophthalmic lens into a spectacle frame
Publication Date: 2026.03.18 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP4348343B1 patent drawingFigure 1~2a
  • EP4348343B1 patent drawingFigure 2b~2e
  • EP4348343B1 patent drawingFigure 2f~3

AI summary

A photography and thermography combining method of obtaining, for the chosen spectacle frame model of a spectacle wearer, at least one fitting parameter to fit an ophthalmic lens into the spectacle frame model, the method comprising the following steps: taking a photograph of the wearer's face with spectacles having the chosen spectacle frame model, taking a thermogram (21) of the wearer's face with said spectacles, identifying the spectacles' contour (23) in the thermogram (21), overlaying the identified contour (23) or a boxing shape derived from the identified contour onto the photograph, thus obtaining a composite image, obtaining the at least one fitting parameter from the composite image