Ophthalmic Lens Wafer Assembly for Curl-Free Thermoset Casting
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Solution Overview
Problem
Current methods for manufacturing thermoset ophthalmic lenses with embedded wafers face issues such as uncontrolled stresses, wafer curling, positioning defects, and non-uniformity due to glue spots, leading to microbubbles and casting defects, while being costly and time-consuming.
Innovation Solution
A method involving affixing a wafer to a mould part using a continuous glue string, forming a cavity, filling it with monomer liquid, and curing simultaneously to create thermoset material portions, ensuring precise positioning and avoiding stress on the wafer, compatible with existing lens mould designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wafer is fitted into a groove provided in a gasket, then the wafer is positioned in the lens mould, but uncontrolled stresses are caused in the gasket due to radial expansion
Solution Approach 1:
The invention removes the gasket component from the lens mould assembly, replacing it with a wafer holder that integrates wafer positioning and mould sealing functions. This extraction eliminates the source of radial expansion stresses while maintaining precise wafer positioning through the holder's designed geometry and wafer attachment mechanism.
Solution Approach 2:
The invention merges the wafer positioning function and the mould sealing function into a single integrated wafer holder structure. This consolidation eliminates the need for separate gasket components that cause stress, while the holder simultaneously secures the wafer and seals the lens mould cavity during the curing process.
2Stability of the object's composition
If glue spots are used to secure the wafer to the mould part, then the wafer is fixed, but positioning variations occur leading to microbubbles and casting defects
Solution Approach 1:
The invention removes the glue spots from the wafer attachment process, replacing them with a mechanical fixation system using the wafer holder. This extraction eliminates the positioning variations and defects associated with glue application while maintaining secure wafer fixation through the holder's clamping or positioning mechanism.
Solution Approach 2:
The wafer holder serves as an intermediary device between the wafer and the lens mould, providing a controlled mechanical interface for wafer positioning and fixation. This intermediary structure ensures uniform positioning through its designed geometry, replacing the unreliable glue spot method with a precise mechanical system.
3Reliability
If a clip is used for pressing the mould parts against the gasket, then the mould is sealed, but gasket deformation occurs
Solution Approach 1:
The invention removes both the gasket and the clip components from the lens mould assembly, replacing them with an integrated wafer holder that provides sealing through its own structure. This extraction eliminates gasket deformation while maintaining reliable mould sealing, as the holder's design inherently provides the necessary seal without requiring external clamping forces.
4Ease of manufacture
If the wafer is affixed using glue spots with gaps, then the wafer can be attached to the mould part, but the wafer curls due to internal stresses and thickness variations
Solution Approach 1:
The invention removes the glue spots from the wafer attachment process and replaces them with a mechanical fixation system using the wafer holder. This extraction eliminates the wafer curling issue caused by glue application while maintaining ease of manufacture through the simplified mechanical attachment process that uniformly distributes fixing forces across the wafer surface.
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 produces identical, defect-free ophthalmic lenses without significantly increasing costs or time, using commercially available glue dispensers for controlled wafer positioning and stress-free assembly.
Implementation Method 1
simultaneously curing the first and second monomer-containing liquid amounts contained within the lens mould
Data Source
Figure 1~2b
Figure 3a~3e
Figure 3f~4d
AI summary
A method for manufacturing an ophthalmic lens that includes a wafer (13) and two thermoset material portions comprises forming a sub-assembly that is comprised of one mould part (101), the wafer and a continuous glue string (30). The glue string connects a peripheral edge of the wafer to the mould part, thereby forming a first cavity (C1). Said first cavity is filled with monomer-containing liquid and sealed. The sub-assembly can then be used to form a complete lens mould (100). The method alleviates drawbacks of previous methods, in particular when the wafer spontaneously curls.