Spectacle Lens Prism Thinning Visual Deviation Correction
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Solution Overview
Problem
Spectacle lenses with prism thinning processing exhibit deviations in visual lines due to varying prism effects when viewing in different directions, making it difficult for users to adapt to wearing such lenses, as the deviation angle of rays from the prism measurement reference point to the lens periphery is not constant.
Innovation Solution
A spectacle lens design incorporating a first refractive portion with a positive spherical power and a second refractive portion with a higher power, where the prism base direction is set towards the second refractive portion, and the lens surface is shaped to ensure a mean curvature difference that minimizes prism-induced deviations by adjusting the slope of the optical surfaces to align ray vectors parallel to the target group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If prism thinning processing is applied to reduce lens thickness, then lens weight and thickness are reduced, but visual line deviation occurs when viewing in different directions
Solution Approach 1:
The patent applies different curvatures to different regions of the lens surface. Specifically, the first curvature is applied in the vertical direction and the second curvature is applied in the horizontal direction, creating local variations in optical properties that compensate for prism-induced deviations while maintaining overall lens thinness.
Solution Approach 2:
The patent changes the curvature parameters of the lens surface to eliminate visual line deviations. By adjusting the curvatures in different directions and regions, the optical path is modified to maintain constant deviation angles, thereby resolving the visual comfort issue while preserving the weight reduction benefit of prism thinning.
2Length of stationary object
If prism thinning processing is applied to reduce lens thickness, then lens thickness is reduced, but the deviation angle of rays varies from prism measurement reference point to lens periphery
Solution Approach 1:
The patent employs dual curvatures on the lens surface - a first curvature in the vertical direction and a second curvature in the horizontal direction. This curved surface design allows the lens to maintain reduced thickness while controlling ray deviation angles, thereby achieving both thickness reduction and optical precision.
Solution Approach 2:
Different curvature values are applied to different regions of the lens surface. The first curvature operates in the vertical direction and the second curvature in the horizontal direction, creating localized optical corrections that maintain constant deviation angles across the lens periphery while keeping the lens thin.
3Length of stationary object
If prism thinning processing is applied to reduce lens thickness, then lens thickness is reduced, but adaptation difficulty increases for users
Solution Approach 1:
The patent modifies the curvature parameters of the lens surface to eliminate visual line deviations that occur with prism thinning. By carefully selecting and applying different curvatures in vertical and horizontal directions, the optical performance is optimized to maintain constant deviation angles, thereby improving user adaptation while preserving lens thinness.
Solution Approach 2:
The application of dual curvatures creates a more complex lens surface geometry that compensates for the optical distortions introduced by prism thinning. This curved design helps maintain consistent visual line alignment across different viewing directions, facilitating easier user adaptation.
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
The design effectively reduces visual line deviations between the left and right eyes, ensuring a consistent viewing experience by equalizing the prism effect across different directions, thereby improving user adaptation and comfort.
Implementation Method 1
a spectacle lens includes a first refractive portion having a first refractive power, and a second refractive portion having a second refractive power larger than the first refractive power
Data Source
AI summary
In a spectacle lens added with prism thinning, a spherical refractive power of a first refractive portion is positive, and a prism base direction of a prism provided at a prism measurement reference point is set toward a second refractive portion side; a mean value of a difference of a mean curvature in a lens curved surface along a direction passing through a midpoint of a connecting line between two alignment reference marks and orthogonal to the connecting line with respect to a mean curvature in a lens curved surface along a direction of a lens without prism is smaller in a first-refractive-portion-side region from a fitting point than that in a second-refractive-portion-side region from the fitting point.