Progressive Lenses Reducing Peripheral Mean Sphere
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Solution Overview
Problem
Traditional merit functions used in progressive addition lens design fail to independently distribute power components, leading to suboptimal and unsatisfactory lens configurations due to interdependence of sphere, cylinder, and cylinder axis, resulting in less than ideal optical power distribution.
Innovation Solution
An improved merit function is introduced, relaxing the cylinder constraint below a specific distance from the near reference point and adding a new term to calculate the mean sphere, allowing for a reduced mean sphere distribution while maintaining the usability of the near region, by modifying the merit function to Φ=Φ′0+Φ1, where Φ′0 relaxes the cylinder constraint and Φ1 focuses on points with significant cylinder values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional merit function is used for progressive lens design, then the lens configuration follows conventional optimization, but the power components (sphere, cylinder, cylinder axis) cannot be independently distributed leading to suboptimal results
Solution Approach 1:
The patent segments the merit function into two independent parts: Φ′0 (original merit function for optical quality) and Φ1 (new term for mean sphere control). This segmentation allows independent optimization of power components, enabling precise control over sphere, cylinder, and cylinder axis distributions without mutual interference, thereby resolving the suboptimal results caused by interdependence in traditional single merit functions.
Solution Approach 2:
The patent introduces a new parameter Φ1 that specifically targets mean sphere distribution, changing the optimization landscape from traditional single-parameter merit functions. By adding this new parameter dimension, the system can independently control power component distributions, transforming the optimization problem to achieve superior lens design precision without excessive complexity.
2Quantity of substance
If the merit function is modified to reduce mean sphere by adding Φ1 term, then mean sphere is reduced by over 50%, but the cylinder constraint must be relaxed below certain distance from near reference point
Solution Approach 1:
The patent applies local quality by differentiating cylinder constraint requirements across different lens regions. Below a specific distance from the near reference point, the cylinder constraint is relaxed (allowing non-zero values), while above this distance, traditional zero-cylinder constraints are maintained. This localized approach enables mean sphere reduction through Φ1 term without compromising overall optical quality in critical viewing zones.
Solution Approach 2:
The patent implements partial action by selectively applying cylinder constraints only in specific lens regions rather than uniformly across the entire lens. By relaxing constraints only below the near reference point where the Φ1 term operates, the system achieves excessive reduction in mean sphere (over 50%) while maintaining sufficient optical precision in the primary visual field above this boundary.
3Ease of operation
If traditional merit function optimization is performed, then the lens achieves conventional visual performance, but the peripheral mean sphere remains high reducing overall optical efficiency
Solution Approach 1:
The patent adds another dimension to the optimization problem by introducing the Φ1 term that specifically addresses mean sphere control in the peripheral regions. This dimensional expansion allows the system to simultaneously maintain conventional visual performance (through Φ′0) while reducing peripheral mean sphere (through Φ1), thereby improving optical efficiency without sacrificing ease of operation or visual comfort.
Data Source
AI summary
An improved method for configuring progressive ophthalmic lenses is disclosed. The method includes computing a traditional merit function with two changes. First, the merit function computation is limited by calculating only a preferred distance from the meridian rather than until 0. Second, an additional term is added to the merit function that calculates the mean sphere at a point that is at a reduced range from the maximum unwanted cylinder, rather than the entire range.