Ophthalmic Lens Mold Electrostatic Charge Defect Removal
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Solution Overview
Problem
The existing methods for manufacturing ophthalmic lenses often result in excess polymer ring defects during the molding process, which complicates the removal of lenses from molds and increases production costs and manual labor.
Innovation Solution
Applying a static charge differential between the mold parts, specifically a negative charge to the back curve mold part and a positive charge to the front curve mold part, reduces the incidence of excess polymer ring defects by altering the surface energy and adhesion properties, allowing for improved lens removal and automation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If monomer material is supplied in excess to the mold cavity, then the lens can be fully formed, but excess polymer ring defects are created around the lens
Solution Approach 1:
The patent applies electrostatic charge to the mold surfaces to convert the harmful adhesion of excess polymer into a beneficial selective release mechanism. The charged mold surfaces cause the excess polymer ring to adhere preferentially to the mold rather than remaining on the lens, thereby converting the defect into a controllable byproduct that can be easily removed.
Solution Approach 2:
The patent changes the surface energy parameters of the mold by applying electrostatic charge. This parameter change alters the adhesion characteristics between the polymer material and the mold surface, enabling selective adhesion of excess polymer to the mold while allowing the lens to be released cleanly.
2Ease of operation
If traditional mold separation is used, then the lens can be released, but manual removal of flashing is required
Solution Approach 1:
By charging the mold surfaces, the patent converts the problematic adhesion of excess polymer into a beneficial automatic separation mechanism. The excess polymer remains on the charged mold surface while the lens releases cleanly, enabling automated removal without manual intervention.
Solution Approach 2:
The patent replaces the mechanical manual removal process with an electrostatic field-based automatic separation system. The electrostatic charge differential between the mold and the polymer material eliminates the need for mechanical picking and manual handling.
3Manufacturing precision
If electrostatic charge is applied to mold parts, then excess polymer ring defects are reduced, but additional charging equipment is required
Solution Approach 1:
The patent modifies the surface energy parameters of the mold by applying electrostatic charge, which fundamentally changes the adhesion characteristics. This parameter change enables selective adhesion/release behavior that reduces excess polymer defects without requiring complex additional processing equipment.
Solution Approach 2:
The electrostatic charge acts as an intermediary field between the mold and the polymer material. This intermediary enables controlled adhesion and release behavior, allowing the system to achieve precise manufacturing results with relatively simple charging equipment rather than complex mechanical or chemical systems.
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 occurrence of excess polymer ring defects from over 30% to less than 10%, and in some cases to less than 1%, enhancing the efficiency and automation of the lens manufacturing process while minimizing manual intervention.
Implementation Method 1
Applying a static charge differential between the mold parts, specifically a negative charge to the back curve mold part and a positive charge to the front curve mold part, reduces the incidence of excess polymer ring defects by altering the surface energy and adhesion properties
Data Source
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AI summary
The present invention includes molds for forming ophtalmic lenses, such as contact lens. In particular, the present invention relates to apparatus, molds and methods for fashioning an ophthalmic lens with a mold assembly that includes two or more mold parts with at least one of the mold parts (101,102) including a flange surface (107A, 107B) and a static charge apparatus (109, 110) operative to impart a static charge differential between each mold part, including the flange surface.