Lens Support Bevel and Vacuum for Uniform Coating
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Solution Overview
Problem
Existing methods for coating ophthalmic lenses, particularly multifocal lenses, often result in defects such as uneven coating thickness and line defects due to incompatible surface tension and physical structures on the forward surface, leading to cosmetic and functional issues when exposed to actinic radiation.
Innovation Solution
A method involving a lens support with a central axis and upper beveled surface that maintains the outer edge of the lens in fixed abutment during coating application, using negative pressure within a central lens support chamber to ensure uniform coating on the rear surface, preventing shifting and ensuring proper adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coating is applied to the forward surface of a multifocal lens, then the lens can be coated, but defects such as uneven coating thickness and line defects occur due to incompatible surface tension and physical structures
Solution Approach 1:
The patent inverts the conventional coating approach by applying coating to the rear surface of the lens instead of the forward surface. This reversal avoids the defects caused by incompatible surface tension and physical structures on the forward surface, while still achieving the desired optical filtering effect through the lens material.
Solution Approach 2:
The patent introduces a rear surface coating layer as an intermediary solution. This coating layer, applied to the rear surface, serves as a mediator that provides the optical filtering functionality without directly contacting the problematic forward surface features, thus avoiding coating defects.
2Manufacturing precision
If the lens is held in place during coating application, then coating uniformity can be achieved, but the holding mechanism adds device complexity
Solution Approach 1:
The lens support structure utilizes the lens's own geometry and the support's beveled surface geometry to achieve self-alignment and stable positioning. The abutment between the lens outer edge and the beveled surface creates a natural holding mechanism that maintains coating uniformity without requiring additional active holding devices.
Solution Approach 2:
The patent employs negative pressure (vacuum) applied to the rear surface of the lens through the lens support to secure the lens in place during coating application. This pneumatic holding method provides stable lens positioning and coating uniformity while maintaining relatively simple device architecture.
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 prevents defects by maintaining a stable interface during coating, resulting in uniform and cosmetically acceptable coatings on the rear surface of ophthalmic lenses, enhancing their optical properties and cosmetic appeal.
Implementation Method 1
forming negative pressure within said central lens support chamber, thereby maintaining said outer edge of said forward surface of said lens and said upper beveled surface of said lens support in fixed abutment with each other
Data Source
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AI summary
The present invention relates to a method of coating a lens, such as a segmented multifocal lens. The method includes, providing a lens support (1), which is in the form of a ring, that includes a central axis (11), an outer wall (14), an inner wall (17) that is positioned between the central axis and the outer wall, an upper beveled surface (20) that converges downward toward the central axis, and a lower surface (29). The method further includes positioning a lens (3) such that an outer edge (74) of a forward surface (65) thereof abuts a portion of the upper beveled surface of the lens support. At least one coating composition is applied over the rear surface (68) of the lens, so as to form a coated lens (3') having at least one coating layer (89) over the rear surface thereof.