Optical Patch Surface Segmentation for Mould Cost Reduction

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Solution Overview

Problem

The high cost and complexity of manufacturing mould inserts for optical patches, particularly those with Fresnel structures, due to the vast number of combinations required to cover all possible ophthalmic prescriptions, result in a significant economic burden.

Innovation Solution

A method to determine a limited set of front and rear patch surfaces, where each rear surface features a Fresnel structure superimposed on a pseudo-spherical base, allowing for the production of optical patches that meet various prescriptions using a reduced number of mould inserts by segmenting prescriptions and reusing surfaces across segments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a large number of mould inserts are manufactured to cover all possible ophthalmic prescriptions, then all prescription needs can be satisfied, but manufacturing costs and device complexity increase significantly

Engineering Contradiction:

Improvecoverage of ophthalmic prescriptionsVSAvoidnumber of mould inserts

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention segments the optical patch into two separate surfaces: a front surface and a rear surface with Fresnel structure. By dividing the prescription parameters into two independent sets (front surface parameters and rear surface parameters), the system can combine these segments to achieve full prescription coverage. This segmentation allows the same front surface to be paired with different rear surfaces, and vice versa, reducing the total number of mould inserts needed from 166 to a much smaller number while still covering all prescription combinations.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If mould inserts with Fresnel structure are manufactured for each prescription combination, then optical precision is maintained, but manufacturing cost increases due to the complex structure

Engineering Contradiction:

Improveoptical power and astigmatism accuracyVSAvoidmould insert manufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention makes the front surface and rear surface independently functional. The front surface can serve multiple prescription combinations when paired with different rear surfaces, and each rear surface with Fresnel structure can be paired with multiple front surfaces. This multi-functionality reduces the need to manufacture separate mould inserts for every prescription combination, thereby lowering manufacturing costs while maintaining optical precision through the controlled design of each surface.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Shape

If the thickness of optical patch is limited for aesthetic reasons, then appearance is improved, but achieving desired optical power becomes more difficult

Engineering Contradiction:

Improvethickness of optical patchVSAvoidoptical power

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The invention employs a Fresnel structure on the rear surface of the optical patch, which uses concentric circular grooves or ridges to achieve the desired optical power in a thinner profile. This curved, periodic structure allows light to be focused or diverged as required while maintaining a limited thickness for aesthetic purposes. The Fresnel structure effectively replaces what would traditionally require greater thickness, thus resolving the contradiction between aesthetic appearance and optical performance.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 significantly reduces the number of mould inserts needed, from 166 to approximately 26, thereby lowering production costs and simplifying the manufacturing process while maintaining optical precision across diverse prescriptions.

Implementation Method 1

one of the surfaces of each optical patch has a Fresnel structure suitable for producing the desired optical power

Methodology Applied

Scientific EffectFresnel diffraction: Fresnel Diffraction

Implementation Method 2

an optical patch is a member of light-refracting material with front and rear surfaces which are designed so that the patch acts as a lens for producing optical power and possibly astigmatism

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9285608B2Method for determining front and rear surfaces for optical patches

Publication Date: 2016.03.15 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)

AI summary

Optical patches are assigned to prescriptions so as to reduce the total number of patch surfaces which are involved. The prescriptions are produced by varying at least one of a front patch surface (S1) and rear patch surface (S2) which are combined to form an optical patch, in accordance with prescription segments. The front patch surfaces (S1) are pseudo-spherical and the rear patch surfaces (S2) include a Fresnel structure superimposed on a pseudo-spherical base shape.