Referencing Element for Optical Lens Positioning

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Solution Overview

Problem

The existing methods for providing reference markings on optical lenses are costly and prone to inaccuracies due to material deformation during the molding process, leading to potential optical errors.

Innovation Solution

A method that allows for the creation of semi-finished optical lenses without pre-existing reference markings on the molds, using a referencing element added to the lens surfaces through measurement and marking techniques such as engraving or additive manufacturing, which can be used to accurately determine the position and orientation of the lens surfaces during manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If reference markings are provided by molding with engraved markings on the mold, then the reference system is established on the finished face, but the position accuracy deteriorates due to material deformation during cooling

Engineering Contradiction:
Improveposition accuracy of reference markingsVSAvoiduncertainty on positions of reference markings
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by adding reference markings to the finished face before the machining process, but using a method that avoids the cooling deformation issue. The semi-finished lens is provided with reference markings through a process that doesn't involve molding cooling, thereby establishing an accurate reference system prior to back face machining without the positioning uncertainty caused by thermal contraction.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If reference markings are engraved on the finished face during molding, then the reference system is established, but the manufacturing cost increases due to expensive molds

Engineering Contradiction:
Improvereference system establishmentVSAvoidmold cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent extracts the reference marking function from the mold itself. Instead of requiring expensive molds with pre-engraved reference markings, the method provides reference markings directly on the finished face of the semi-finished lens through a separate, simpler process. This separates the reference marking function from the molding tooling, eliminating the need for costly customized molds while maintaining reference system establishment.

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If the back face is machined to generate the required shape and positioning, then the corrective prescription is achieved, but optical errors occur when surface positioning is inaccurate

Engineering Contradiction:
Improvesurface positioning accuracyVSAvoidoptical error rate
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies feedback by using the reference markings on the finished face as a basis for accurately positioning and measuring the back face during machining. The reference system provides a feedback mechanism that ensures the machined back face surface is correctly positioned relative to the front face, thereby achieving the required corrective prescription without optical errors that would result from inaccurate positioning.

Inventive Principle:
Principle #23Feedback

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 approach results in cheaper and more accurate optical lenses by eliminating the need for expensive molds and reducing deformation-related uncertainties, thereby improving the precision and cost-effectiveness of the manufacturing process.

Implementation Method 1

During the cooling step, the material may deform creating an uncertainty on the positions of the reference markings

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

During the cooling step, the material may deform

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

the referencing element comprises markings realized by engraving

Methodology Applied
Scientific EffectEngraving:

Implementation Method 4

the referencing element comprises markings realized by engraving and/or additive manufacturing

Methodology Applied
Scientific EffectAdditive manufacturing: 3D Printing

Data Source

PatentEP2961592B1Method for providing a referencing element to an optical lens member
Publication Date: 2021.04.07 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP2961592B1 patent drawingFigure 1~2
  • EP2961592B1 patent drawingFigure 3A~3B
  • EP2961592B1 patent drawingFigure 4~5

AI summary

Method for providing a referencing element to an optical lens member, the method comprising: an optical lens member providing step, during which an optical lens member (10) is provided, the optical lens member comprising a first optical surface (11) comprising a surface design associated with a first reference system and a second optical surface to be manufactured (13), the first and second optical surfaces are connected by an external periphery surface, a measuring step during which the first optical surface of the optical lens member is measured and the first reference system is determined, wherein the reference system is determined according to the shape and orientation of the first optical surface (11), a referencing step during which a referencing element (111) is added to the optical lens member, wherein the referencing element identifies the first reference system.