Micro-Structured Optical Article Manufacturing With Tie-Layer Bonding

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Solution Overview

Problem

Existing methods for manufacturing micro-structured optical articles, such as lenses, face challenges in maintaining the shape integrity and optical design of microstructures due to deformation during the injection overmolding process, and require specific material properties for bonding that are difficult to achieve.

Innovation Solution

A three-layered composite optical article is manufactured using a low index and low heat resistance tie-layer between the wafer and lens layers, preserving microstructure shape integrity and facilitating bonding, with specific thermoplastic materials chosen for each layer to maintain optical fidelity and aesthetic appeal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If injection overmolding is used to encapsulate microstructures, then the microstructures are protected from external damage, but the microstructures soften and deform under high heat and pressure causing loss of shape integrity

Engineering Contradiction:
Improveprotection of microstructuresVSAvoidshape integrity of microstructures
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The encapsulation process is divided into multiple sequential injection molding steps with different materials and temperature conditions. The first injection uses a material compatible with microstructure stability, followed by additional injections for full encapsulation, allowing protection without direct exposure to damaging conditions

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The injection molding parameters are optimized to use lower temperatures and adjusted pressure levels that provide sufficient encapsulation protection while remaining below the softening threshold of the microstructure material, preventing deformation

Inventive Principle:
Principle #35Parameter changes

2Strength

If a hard coating is deposited on the lens surface to protect from scratches, then the lens is protected, but the geometric shape of the lens is altered causing shift of optical design

Engineering Contradiction:
Improvescratch resistanceVSAvoidoptical design accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The microstructures are fully encapsulated within the lens body before any surface coating is applied. This preliminary encapsulation creates a stable geometric foundation that prevents coating-induced shape changes from affecting the optical design

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The encapsulating material acts as an intermediary layer between the microstructures and the external environment, providing mechanical protection and maintaining geometric stability while allowing a separate hard coating to be applied without directly impacting the microstructure geometry

Inventive Principle:
Principle #24Intermediary (Mediator)

3Length of stationary object

If the lens thickness is reduced to enhance aesthetic appeal, then the aesthetic appeal is improved, but the materials must be carefully selected to maintain bonding strength and optical fidelity

Engineering Contradiction:
Improvelens thicknessVSAvoidbonding strength between layers
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

Multiple materials with complementary properties are combined in a layered composite structure. Each material is selected for specific properties (optical clarity, bonding compatibility, thermal stability), and their interfaces are engineered to maintain strong adhesion even in thin configurations

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

Different regions of the lens structure are assigned different material properties optimized for their specific functions. Interface regions between layers are treated with surface preparations or transition layers that enhance bonding, while central regions optimize optical performance, allowing thin overall design without sacrificing strength

Inventive Principle:
Principle #3Local quality

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 method ensures the microstructures retain their shape and optical properties, allowing for effective myopia control while reducing overall lens thickness and enhancing aesthetic appeal.

Implementation Method 1

depositing, on said micro-structured surface, a second optical thermoplastic material having a refractive index and a glass transition temperature lower than a respective refractive index and glass transition temperature of the first optical thermoplastic material, thus obtaining an intermediate tie-layer which encapsulates the microstructures

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

depositing, on said tie-layer, a third optical thermoplastic material having a refractive index and a glass transition temperature higher than the respective refractive index and glass transition temperature of the second optical thermoplastic material of the tie-layer, thus obtaining a body layer

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Data Source

PatentEP4640416A1Method for manufacturing a micro-structured optical article
Publication Date: 2025.10.29 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP4640416A1 patent drawingFigure 1~3
  • EP4640416A1 patent drawingFigure 4
  • EP4640416A1 patent drawingFigure 5~7

AI summary

Method for manufacturing a micro-structured optical article (70) comprising the steps of: - providing a support layer (56) having microstructures (58) on a back surface, the support layer (56) comprising a first optical thermoplastic material (52); - depositing, on said micro-structured surface, a second optical thermoplastic material (60) having a refractive index (RITie) and a glass transition temperature (TgTie) lower than a respective refractive index (RIWafer) and glass transition temperature (TgWafer) of the first optical thermoplastic material (52), thus obtaining an intermediate tie-layer (62) which encapsulates the microstructures (58) ; - depositing, on said tie-layer (62), a third optical thermoplastic material (66) having a refractive index (RILens) and a glass transition temperature (TgLens) higher than the respective refractive index (RITie) and glass transition temperature (TgTie) of the second optical thermoplastic material (60) of the tie-layer (62), thus obtaining a body layer (68), the support layer (56), the tie-layer (62) and the body layer (68) forming altogether said micro-structured optical article (70).