Melon-Shaped Optical Lens Blanks for Reducing Prismatic Effects
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Solution Overview
Problem
Existing spectacle lenses, particularly those designed for presbyopia correction, often suffer from prismatic effects that cause blurring and discomfort, especially in horizontal directions, and have aesthetic issues due to visible transitions between different surface types, which can be hazardous and unpleasant for users.
Innovation Solution
The use of optical lens blanks with first and second surfaces featuring melon-shaped geometries, allowing for continuous curvature changes along vertical and horizontal axes, mimicking eye movements, and employing ellipsoidal designs with specific radii ratios to create spectacle lenses with reduced prismatic effects and improved aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If toric surfaces are arranged decentrally in the front of the lens blank to correct presbyopia, then near-vision correction is improved, but prismatic effects cause blurring and discomfort in horizontal viewing directions
Solution Approach 1:
The patent applies continuous curvature changes on the front surface of the lens blank, transitioning from traditional spherical or toric surfaces to surfaces with continuously variable curvature in multiple directions. This allows the lens to correct presbyopia while maintaining optimal optical properties across all viewing directions, eliminating the prismatic effects caused by abrupt surface transitions.
Solution Approach 2:
The invention changes the curvature parameters of the front surface continuously rather than using discrete spherical or toric zones. By varying the curvature radius continuously across the lens surface, the patent achieves smooth transitions between different focal points for near and distance vision without creating harmful prismatic effects at zone boundaries.
2Adaptability or versatility
If visible transitions are created between different surface types in the lens, then functional zones are distinguished, but aesthetic appeal is reduced and user comfort is compromised
Solution Approach 1:
The patent implements local variations in surface curvature that are optimized for specific viewing zones (near, intermediate, distance vision) while maintaining smooth transitions between these zones. The continuous curvature changes allow each region to have its optimal optical properties without creating visible boundaries or abrupt transitions that would compromise aesthetics.
3Adaptability or versatility
If multiple types of lens blanks are produced to accommodate different visual defects, then correction versatility is improved, but production complexity and inventory requirements increase
Solution Approach 1:
The patent creates a universal lens blank design with continuous curvature changes that can accommodate multiple types of visual defects (myopia, hyperopia, presbyopia, astigmatism) within a single blank type. The flexible curvature profile allows a single lens blank design to serve multiple correction purposes, reducing the need for maintaining separate inventory for different visual defect types.
Data Source
AI summary
An optical lens blank includes a first and a second lens surface, which are arranged opposite each other and which are delimited at a lens circumference, wherein the first lens surface has a surface geometry that corresponds to a first partial cutout from a first melon shape. A range of blanks consisting of such lens blanks have first lens surfaces of varying degrees of curvature, wherein the different degrees of curvature are based on different melon shapes. Finally, a method for producing a spectacle lens from such an optical lens blank includes mechanically shaping at least the first or second surface, and separating a cutout from the mechanically shaped lens blank.