Digital Surfacing Aspherical Eyeglass Lenses
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Solution Overview
Problem
Traditional eyeglass lens manufacturing techniques are limited in creating non-spherical surfaces and curvatures, resulting in bulky lenses with aesthetic and optical drawbacks, such as the 'coke bottle effect', due to the incremental nature of curvature adjustments and the inability to produce custom, patient-specific lenses with optimal optical and cosmetic benefits.
Innovation Solution
The system employs digital surfacing to create aspherical, custom-designed back surfaces on lenses, allowing for non-spherical curvature changes from the center to the periphery, using conic-based surfaces like hyperbolic curves, enabling precise optical and cosmetic tailoring of lenses with reduced thickness and enhanced optical quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional lathing and lapping techniques are used to create lens surfaces, then the manufacturing process is simple and equipment is readily available, but the curvature is limited to incremental adjustments (minimum difference around 0.125 diopters) and generally spherical surfaces only
Solution Approach 1:
The patent replaces traditional mechanical lathing and lapping systems with a digital surfacing system that uses computer-controlled material removal. This substitution enables continuous curvature variation and non-spherical surface creation, resolving the contradiction by achieving both high precision and versatility through digital control rather than mechanical constraints
Solution Approach 2:
The invention changes the fundamental parameters of surface creation from fixed incremental curvature steps to continuous variable curvature control. By implementing digital control over the surfacing process, the system can achieve any curvature value within the range, not just discrete increments, thereby achieving both precision and adaptability
2Reliability
If strong prescription lenses are made with traditional spherical surfaces, then the optical correction is achieved, but the lenses become bulky and create the 'coke bottle effect' at the periphery
Solution Approach 1:
The patent applies local quality by creating different surface curvatures in different regions of the lens. The digital surfacing system allows the periphery of the lens to have a different curvature profile than the center, enabling the optical correction to be maintained while the peripheral thickness is reduced, eliminating the coke bottle effect
Solution Approach 2:
The invention moves from spherical surfaces to aspherical surfaces with varying curvature. By implementing non-uniform curvature across the lens surface, particularly flattening the periphery relative to the center, the system achieves the required optical correction without the bulbous appearance characteristic of strong spherical prescription lenses
3Manufacturing precision
If custom patient-specific lenses with optimal optical and cosmetic benefits are created, then the cosmetic appearance and optical quality are improved, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent implements preliminary action by pre-programming the digital surfacing system with patient-specific optical and cosmetic requirements before the actual surfacing process. This allows custom lenses to be manufactured efficiently by having the precise surface specifications ready in advance, reducing the time and complexity of the manufacturing process while maintaining high precision
Data Source
AI summary
A system and method of forming surfaces on eyeglass lenses is described. In some examples, the surface is a spherical, cylindrical or spherocylindrical surface at a center of the lens and an aspherical surface at a periphery of the lens. In some examples, forming the surface on the lens reduces the thickness of the lens at the periphery of the lens.