Embedded Hydrogel Contact Lens Molding for Hole-Free Insert Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a challenge in producing embedded hydrogel contact lenses with inserts positioned accurately and efficiently, as conventional methods using molds with positioning guides result in small holes susceptible to bioburden trapping.
Innovation Solution
A method involving a lens mold with alignment features on the insert's front surface, which are rotationally symmetric and protrude to minimize contact area, allowing precise central alignment during molding, eliminating the need for positioning guides and preventing hole formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If molds with positioning guides (posts) are used to precisely position inserts, then manufacturing precision is improved, but small holes are formed in the resultant lenses which are susceptible to bioburden trapping
Solution Approach 1:
The invention removes the positioning guide posts from the mold structure entirely. Instead of using posts that create holes, the patent uses alignment features directly on the insert itself (such as circumferential edges or asymmetric patterns) that engage with corresponding features on the mold surface. This extraction of the posts eliminates the source of the harmful holes while preserving the positioning function through alternative means.
Solution Approach 2:
Conventional approaches place positioning guides on the mold. The invention inverts this approach by placing alignment features on the insert itself rather than on the mold. This inversion allows the insert to self-align during placement, eliminating the need for mold posts and the resulting harmful holes.
2Manufacturing precision
If positioning guides (posts) are used in molds, then insert positioning accuracy is improved, but device complexity increases due to additional mold features
Solution Approach 1:
The invention extracts and removes the positioning guide posts from the mold structure, simplifying the mold design. The positioning function is transferred to the insert itself through integrated alignment features, reducing mold complexity while maintaining positioning accuracy.
Solution Approach 2:
The alignment features on the insert serve multiple functions: they provide positioning accuracy, guide orientation, and ensure proper placement during the molding process. This multi-functionality eliminates the need for separate positioning guides on the mold, reducing overall device complexity.
3Productivity
If conventional cast-molding process is used, then production efficiency is maintained, but the process cannot achieve accurate insert positioning without creating holes
Solution Approach 1:
The alignment features are pre-formed on the inserts before they are placed in the mold. This preliminary preparation of alignment features allows for accurate positioning to be achieved during the standard cast-molding process without requiring additional steps or modifications to the molding procedure, thus maintaining production efficiency while improving positioning precision.
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 accurate positioning of inserts without forming holes, reducing bioburden buildup and enabling consistent production of embedded hydrogel contact lenses.
Implementation Method 1
curing the lens-forming composition in the molding assembly to form an embedded hydrogel lens precursor that comprise a bulk hydrogel material formed from the lens-forming composition and the insert embedded in the bulk hydrogel material
Implementation Method 2
During the lens hydration, the hydrogel contact lenses will absorb water and typically can swell significantly in size
Data Source
AI summary
The invention relates to a method for producing embedded hydrogel contact lenses each having an insert that comprises alignment features capable of capable of aligning the insert in depth and radial position in a female mold half during cast molding of an embedded hydrogel contact lens. The alignment features protrude from the front surface, are rotationally symmetric with respect to the central axis of the insert and independently have a shape having a curvature being greater than 2 folds of the curvature of the molding surface so as to minimize contacting area between the alignment features and the molding surface. The use of such an insert can simplify the process for producing embedded hydrogel contact lenses and enable the process to be implemented readily in an automatic production.