Silicone Hydrogel Lens Demolding by Vacuum and Mold Deformation
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Solution Overview
Problem
Existing methods for producing silicone hydrogel contact lenses face challenges in reliably predicting which mold half the lens adheres to, leading to difficulties in separation, increased space utilization of mold halves, and reduced extraction efficiency due to flash and lens handling issues, often requiring solvent soaking or cryogenic cooling which complicates the process and increases costs.
Innovation Solution
Applying a deforming force to the non-optical surface of the mold half, combined with a vacuum force, to separate the mold halves and dislodge the silicone hydrogel lens without tearing, allowing for efficient and rapid separation without liquid soaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a deforming force is applied to separate mold halves, then lens separation is achieved, but the mold surface may be damaged
Solution Approach 1:
A release agent is applied as an intermediary substance between the lens and mold surface. This release agent layer allows the lens to be separated from the mold half when deforming force is applied, preventing direct contact and potential damage between the lens and mold surface while still enabling effective separation.
Solution Approach 2:
The optical density of the lens material is optimized to allow sufficient actinic radiation penetration for complete curing while maintaining mechanical integrity during separation. By controlling the balance between optical density and radiation penetration, the lens achieves adequate curing strength to withstand separation forces without mold surface damage.
2Manufacturing precision
If actinic radiation is used to polymerize the lens material, then the lens is formed, but incomplete polymerization may occur if optical density is high
Solution Approach 1:
The optical density of the lens material is optimized to a specific range that allows sufficient actinic radiation penetration while maintaining the desired mechanical and optical properties of the cured lens. This parameter optimization ensures complete polymerization throughout the lens thickness without requiring excessive radiation energy.
Solution Approach 2:
The polymerization process uses periodic or pulsed actinic radiation exposure rather than continuous exposure. This allows controlled energy delivery that penetrates the lens material effectively, ensuring complete polymerization while managing the total energy input and preventing overheating or incomplete curing.
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
Enhances production yield and reduces space and cost by enabling fast, solvent-free separation of lenses from mold halves, improving extraction efficiency and lens handling, while maintaining lens quality.
Implementation Method 1
Applying a deforming force to the non-optical surface of the mold half, combined with a vacuum force, to separate the mold halves and dislodge the silicone hydrogel lens
Data Source
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AI summary
A method producing contact lenses, including the step of: holding the molded silicone hydrogel contact lens (600) attached to the one of the female mold half or the male mold half (400) with a vacuum supplied with a suction cup; deforming a surface of the one of the female mold half or the male mold half (400) having the molded silicone hydrogel contact lens (600) attached to with a pin (300) so as to separate the molded silicone hydrogel contact lens (600) from the mold half (400) attached to and to transfer the molded silicone hydrogel contact lens (600) to the suction cup; moving the suction cup away from the pin while the suction cup continues to hold the molded silicone hydrogel contact lens (600) remains; applying a compressed gas to blow the molded silicone hydrogel contact lens (600) away from the suction cup into a container.