Embedded Hydrogel Contact Lens Molding Without Insert Guide Posts
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Solution Overview
Problem
Existing methods for producing embedded hydrogel contact lenses with inserts face challenges in accurately positioning the inserts, leading to small holes that trap bioburden and are inefficient for mass production.
Innovation Solution
A method involving multiple mold halves is used to form embedded hydrogel contact lenses without positioning guides, allowing precise placement of inserts between layers of hydrogel materials, eliminating small voids and enabling mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If positioning guides (posts) are used in molds to precisely position inserts, then manufacturing precision of insert placement 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 guides (posts) from the mold structure entirely. Instead of using posts to position inserts, the method relies on the natural alignment and positioning features of the mold cavities themselves. This extraction of the positioning guides eliminates the source of the harmful small holes while maintaining insert positioning precision through alternative means such as cavity geometry and material flow control.
Solution Approach 2:
Rather than using positive positioning structures (posts) that create holes, the invention uses negative positioning - relying on the absence of posts and using the mold cavity geometry, material viscosity, and curing process to achieve precise insert positioning. The positioning function is inverted from active structural elements to passive geometric constraints.
2Ease of manufacture
If conventional full cast-molding process is used to produce hydrogel contact lenses, then manufacturing simplicity is maintained, but the process is time-consuming and inefficient for mass production
Solution Approach 1:
The invention incorporates inserts into the mold cavities before injecting the hydrogel material. This preliminary placement of inserts eliminates the need for separate positioning steps during the molding process itself. The inserts are pre-positioned in the molds, and the hydrogel material is then injected around them, streamlining the manufacturing process for mass production while maintaining simplicity.
Solution Approach 2:
The invention combines the insert placement step with the molding step into a single integrated process. Rather than separately positioning inserts and then molding the lenses, the method merges these operations by incorporating inserts directly into the mold cavities before material injection, reducing the number of discrete steps and improving production efficiency.
3Adaptability or versatility
If inserts are embedded in hydrogel contact lenses for various purposes, then lens functionality is enhanced, but the complexity of producing accurately positioned embedded lenses increases
Solution Approach 1:
The invention divides the mold into separate cavities, with each cavity dedicated to holding a specific insert. This segmentation allows different inserts to be independently positioned and secured in their respective cavities before the hydrogel material is injected. The segmentation of the molding process simplifies the handling of multiple inserts while maintaining the versatility to produce lenses with various functional inserts.
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 produces embedded hydrogel contact lenses with accurately positioned inserts, free from bioburden trapping, and allows for different hydrogel material combinations for enhanced comfort and functionality.
Implementation Method 1
curing the first lens-forming composition in the second molding assembly to form a lens precursor
Implementation Method 2
During the lens hydration, the hydrogel contact lenses will absorb water and typically can swell significantly in size
Data Source
Figure 1~2
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AI summary
The invention is directed to an embedded hydrogel contact lens, which comprises an insert sandwiched between two layers of hydrogel materials and can be produced according to a cast molding method including the procedures involving two females halves (FC1 and FC2) and two male halves (BC1 and BC2) and three consequential molding steps involving three molding assemblies: the 1st one formed between FC1 and BC1 for molding an insert; the 2nd one formed between FC1 and BC2 for molding a lens precursor having the molded insert embedded in a layer of a hydrogel material in a way that the front surface of the molded insert merges with the convex surface of the lens precursor; and the 3rd one formed between FC2 and BC2 for molding an embedded hydrogel contact of the invention.