Layered Structure Application on Convex Lenses
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Solution Overview
Problem
Existing methods for applying a layered structure to a convex lens surface, such as ophthalmic lenses, often result in defects like wrinkles or cracks due to curvature mismatches, especially when the lens surface has a small curvature radius.
Innovation Solution
A process involving thermoforming a layered structure to a concave-convex shape, inverting its curvature, and applying it to the lens using controlled pressure, ensuring the final curvature matches the lens surface, while using a pressure-sensitive adhesive for a permanent bond without complex tools or extensive training.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar layered structure is directly applied on a convex lens surface, then the application process is simple, but wrinkles, cracks and delaminations occur due to curvature mismatch
Solution Approach 1:
The layered structure is pre-formed with a curved shape matching the lens surface curvature before application. This preliminary shaping ensures that when the structure is applied to the convex lens surface, the curvature is already compatible, preventing wrinkles, cracks and delaminations that would occur with a planar structure.
Solution Approach 2:
The invention applies curvature to the layered structure by forming it into a spherical or arc-shaped configuration that matches the convex lens surface. This curvature adaptation allows the planar layered structure to conform to the curved lens surface without defects.
2Reliability
If a curved layered structure is pushed against the lens surface with pressure, then contact expands radially, but wrinkles appear near peripheral edges or cracks form in middle parts
Solution Approach 1:
The invention applies different pressure conditions to different regions of the layered structure during application. The peripheral regions are held fixed while pressure is applied to the central region, creating a controlled progression of contact expansion that prevents both peripheral wrinkles and central cracks.
Solution Approach 2:
The peripheral edges of the layered structure are pre-held or clamped during the application process to prevent them from moving or wrinkling as pressure expands the contact zone radially inward. This preliminary constraint on peripheral movement prevents the formation of wrinkles at the edges.
3Manufacturing precision
If the layered structure is thermoformed to match lens curvature, then stress is reduced, but additional processing steps and equipment are required
Solution Approach 1:
The invention changes the physical parameters of the layered structure through thermoforming - heating the material to increase its plasticity and ability to conform to curved surfaces. This parameter change allows the material to be shaped into the required curvature and then set, creating a permanent form-matched structure.
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 process ensures a defect-free, high-quality assembly with reduced stress, suitable for optical applications, enabling rapid implementation and compatibility with various lens curvatures, including progressive addition lenses, without visible defects like wrinkles or cracks.
Implementation Method 1
thermoforming the layered structure so that it becomes curved
Implementation Method 2
applying the first surface of the layered structure against the lens surface via pressure applied on the second surface of the layered structure
Data Source
AI summary
The invention relates to an improvement for applying a layered structure (1) onto a convex surface of a lens (10). After thermoforming the layered structure, a curvature direction of the layered structure is inverted. The structure is then applied on the lens surface by continuously pushing the structure (1) against the lens surface, starting from a contact point between a convex surface of the structure and the convex surface of the lens. The curvature direction of the layered structure is then inverted again, so that it recovers the curvature direction that resulted from thermoforming. Stresses within the layered structure are then reduced, and the structure can be assembled with the lens without defects.