Progressive Power Lens Design for Fitting Point Accuracy
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Solution Overview
Problem
Conventional progressive power lenses deviate from the target addition power when worn, due to factors like target addition power, prescription addition power, spherical power, cylindrical power, cylindrical axis direction, prism power, and prism base direction.
Innovation Solution
A design method for progressive power lenses that involves a simulation step to set a target addition power, a computing step to calculate a correction amount for the deviation, and a design step to adjust the addition power at the fitting point, using a vision simulation and ray tracing method to ensure accurate power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the target addition power is set at the fitting point in the first model, then the design process can proceed systematically, but the addition power deviates from the target value when spectacles are actually worn
Solution Approach 1:
The patent applies preliminary action by performing a vision simulation in advance to predict the deviation between target addition power and actual addition power when spectacles are worn. The simulation results are used to calculate a correction amount that is added to the target addition power before final lens manufacturing, thereby preemptively compensating for the expected deviation and ensuring accurate addition power in the actual wearing condition.
2Manufacturing precision
If vision simulation is performed to calculate correction amount, then addition power accuracy is improved, but design complexity and computational requirements increase
Solution Approach 1:
The patent replaces complex manual trial-and-error lens design with an automated vision simulation system that uses ray tracing methods and computational algorithms. The simulation automatically calculates the addition power distribution, predicts deviation, computes correction amounts, and generates final lens design parameters, thereby reducing design process complexity despite the advanced computational methods employed.
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 method effectively maintains the target addition power at the fitting point when the lens is worn, minimizing deviations and ensuring clear vision at desired distances regardless of user prescription.
Implementation Method 1
A device utilizing a known ray tracing method can be used for the vision simulation
Data Source
AI summary
A vision simulation, on assumption that spectacles are worn, is performed for a first model designed by setting a target additional power of a desirable value at a position corresponding to a fitting point on a principal meridian. A correction amount is computed for correcting the difference between a simulation value obtained for the additional power at the position corresponding to the fitting point on the principal meridian through the vision simulation and the target additional power. A second model is designed by replacing the additional power with a value obtained by the addition of the calculated correction amount to the target additional power.