Progressive Power Lens Design Gradient Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional progressive power lenses have a constant addition power at the fitting point, leading to deteriorated aberration distribution and decreased optical performance, especially when the prescription addition power is small.
Innovation Solution
A method of designing progressive power lenses with an intermediate region where addition power continuously changes, setting a fitting point between the progression-start and progression-end points on the principal meridian, and adjusting the average gradient of addition power based on the prescription addition power to ensure clear vision at a target distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a constant addition power of 0.5 diopters is set at the fitting point regardless of prescription, then the target distance of 2m can be clearly viewed, but the optical performance deteriorates when the prescription addition power is small due to great change in addition power from the start point to the fitting point
Solution Approach 1:
The patent changes the parameter of addition power at the fitting point from a fixed constant (0.5D) to a variable value determined by the prescription addition power. Specifically, when the prescription addition power is less than 1.00D, the addition power at the fitting point is set to one-quarter of the prescription addition power; when the prescription addition power is 1.00D or more, the addition power at the fitting point is set to 0.25D or one-quarter of the prescription addition power, whichever is smaller. This dynamic parameter adjustment resolves the contradiction by adapting the fitting point addition power to different prescription levels, preventing excessive gradient changes for small prescriptions while maintaining clear vision at the target distance.
2Adaptability or versatility
If the addition power changes continuously from the start point to the end point of the corridor, then the progressive power is provided, but the aberration distribution deteriorates when the prescription addition power is small
Solution Approach 1:
The patent applies local quality by differentiating the design approach based on the prescription addition power magnitude. For prescriptions less than 1.00D, the addition power at the fitting point is set to one-quarter of the prescription addition power to reduce the gradient change. For prescriptions of 1.00D or more, the addition power is set to 0.25D or one-quarter of the prescription addition power (whichever is smaller). This localized adjustment of the fitting point addition power based on specific prescription conditions optimizes the aberration distribution while maintaining the progressive power corridor functionality.
Data Source
AI summary
When an addition power at a position corresponding to a fitting point within a prescription addition power is greater than a target addition power set according to a target distance, the target addition power is set as an addition power between a progression-start point and a progression-end point on a principal meridian, and in addition the average gradient of an addition power between the progression-start point and the fitting point is set to differ from an average gradient of an addition power between the fitting point and the progression-end point. When the addition power at the position corresponding to the fitting point within the prescription addition power is equal to or smaller than the target addition power, a gradient of the addition power is made constant in a partial region including at least the fitting point between the progression-start point and the progression-end point on the principal meridian.