Progressive Power Lens Pantoscopic Angle Correction
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Solution Overview
Problem
Conventional progressive power lenses designed with a fixed pantoscopic angle suffer from degradation in optical characteristics when the angle deviates from the standard value due to limitations in spectacle frame designs and materials, leading to significant astigmatic aberrations and average refractive power deviations.
Innovation Solution
The progressive power lens is designed with adjustable surface powers for the outer and inner refractive surfaces, allowing for corrections in the distance and near portions based on the deviation of the pantoscopic angle from the standard value, ensuring that the refractive powers at different Y coordinates on the main fixation line maintain optimal optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed standard pantoscopic angle is used in lens design, then the manufacturing process is simplified, but the optical characteristics degrade when the actual wearing angle deviates from the standard value
Solution Approach 1:
The patent applies parameter changes by incorporating the actual pantoscopic angle as a variable parameter in the lens design process. Instead of using a fixed standard angle, the lens surface powers are calculated based on the specific pantoscopic angle measured for each user's spectacle frame, thereby adapting the optical parameters to match the actual wearing conditions and prevent degradation of optical characteristics
Solution Approach 2:
The patent implements preliminary action by measuring the pantoscopic angle before lens manufacturing and using this measured value to calculate and set the appropriate surface powers in advance. This pre-determination of the wearing angle allows the lens to be optimized for the specific frame configuration before production begins, ensuring optimal optical performance from the start
2Adaptability or versatility
If the pantoscopic angle is adjusted to fit different spectacle frames, then the adaptability to various frame designs is improved, but the astigmatic aberration and refractive power deviation increase
Solution Approach 1:
The patent uses parameter changes by dynamically adjusting the lens surface power parameters based on the measured pantoscopic angle. The calculation formulas incorporate the pantoscopic angle to determine the appropriate spherical and cylindrical powers, thereby compensating for the effects of angle variation and preventing the increase of astigmatic aberration and refractive power deviation that would otherwise occur with frame adjustment
Solution Approach 2:
The patent applies local quality by differentiating the surface power corrections needed at different locations on the lens based on the pantoscopic angle. The design process calculates specific power adjustments for the distance portion and near portion separately, taking into account the local optical requirements at each region when the lens is worn at the measured angle
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 design effectively prevents the degradation of optical characteristics by correcting astigmatic aberrations and average refractive power errors, maintaining targeted optical performance even when the pantoscopic angle deviates from the standard value, thus improving the adaptability of progressive power lenses to various spectacle frame conditions.
Implementation Method 1
The progressive power lens includes two refractive surfaces: an outer refractive surface and an inner refractive surface, at least one of which is a progressive surface
Data Source
AI summary
A progressive power lens that prevents degradation in optical characteristics invited by deviation of a pantoscopic angle from the standard value. The lens includes an outer refractive surface and an inner refractive surface, at least one of which is a progressive surface. Because the amount and direction of aberrations generated in distance and near portions are different, correction is given to either or both of the surface powers of the outer and inner surfaces of the lens such that the distance and near portions are differently corrected.