Progressive Addition Lens Design for Accommodative Convergence
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Solution Overview
Problem
Existing progressive addition lenses do not effectively account for the active use of a wearer's accommodative power margin, leading to issues like image blur and warping when the wearer looks at objects closer than assumed during lens design, as they only consider passive accommodative power and not the maximum accommodative power that can be exerted.
Innovation Solution
A design method and manufacturing system that calculates a first main line of sight considering the accommodative power margin, and a second main line of sight without it, then weights these to determine a final main line of sight that accounts for the active use of accommodative power, ensuring clear vision across a range of distances by optimizing the lens's surface curvature and power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main line of sight is determined based only on passive accommodative power (without considering active use of accommodative power margin), then the lens design is simpler, but image blur and warping occur when wearers look at objects closer than assumed during design
Solution Approach 1:
The patent applies preliminary action by pre-calculating multiple possible main lines of sight corresponding to different object distances before final lens design. The design system proactively determines a range of main lines of sight (from first main line of sight at minimum object distance to second main line of sight at assumed object distance) and prepares weighted combinations in advance, so that when the lens is manufactured, it already incorporates design data that accounts for active accommodative power usage. This eliminates the need for complex real-time adjustments during wear.
Solution Approach 2:
The patent changes the parameter of accommodative power consideration from passive only to including active margin usage. Specifically, it introduces a weighting parameter that combines the first main line of sight (calculated with maximum accommodative power margin) and the second main line of sight (calculated without accommodative power margin) to produce a final main line of sight. This parameter change allows the lens to adapt to actual wearing conditions where wearers actively use their accommodative power, thereby maintaining clear vision without excessive design complexity.
2Reliability
If the main line of sight is displaced more toward the nose side to account for accommodative convergence, then clear vision is maintained at closer distances, but the lens design becomes more complex and requires additional calculations
Solution Approach 1:
The patent applies preliminary action by pre-calculating the first main line of sight that accounts for maximum accommodative power margin and the corresponding inward displacement toward the nose side. This calculation is performed in advance during lens design, and the resulting main line of sight data is stored and used for manufacturing. This eliminates the need for complex real-time calculations during lens wearing, as the displacement has already been optimized in the design phase.
Solution Approach 2:
The patent uses feedback by incorporating information about actual accommodative power usage patterns into the lens design. The system calculates the first main line of sight based on the relationship between object distance and accommodative power margin, using this feedback to determine the appropriate inward displacement of the main line of sight toward the nose side. This feedback mechanism ensures that the lens design reflects actual physiological responses during near vision tasks.
3Adaptability or versatility
If the lens is designed assuming a fixed object distance, then manufacturing is simpler, but the lens does not adapt when wearers actually look at objects at different distances
Solution Approach 1:
The patent changes the parameter of object distance assumption from a single fixed value to a range of values with associated weights. Instead of designing for one assumed object distance, the system calculates main lines of sight for multiple object distances (minimum object distance to assumed object distance) and combines them using weighting coefficients. This parameter transformation allows the lens to adapt to various actual viewing distances while maintaining a systematic manufacturing process based on calculated design data.
Solution Approach 2:
The patent applies preliminary action by pre-calculating the weighted combination of multiple main lines of sight before manufacturing. The design system proactively determines the final main line of sight by combining the first main line of sight (for minimum object distance) and the second main line of sight (for assumed object distance) using predetermined weights. This preliminary calculation of adaptability parameters simplifies manufacturing, as the lens is produced with pre-optimized design data that inherently accounts for multiple viewing scenarios.
Data Source
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AI summary
Provided is a progressive addition lens (1a, 1b), a manufacturing method and a design method therefor, and a progressive addition lens manufacturing system (10), capable of flexibly adapting to an actual use state of a wearer and optimal for each of the wearer, for determining a main line of sight considering not only convergence of the eye occurring with near vision including passive accommodative power but also convergence of the eye induced by using an accommodative power margin of the eye. The design method of a progressive addition lens (1a, 1b) includes a first main line of sight calculation step (S6) of calculating a first main line of sight, where accommodative convergence caused by use of the accommodative power margin of the eye is considered, based on lens design information including at least information of the accommodative power of the eye of a wearer and a final main line of sight determination step (S7) of determining a final main line of sight (2a, 2b) of a lens from the first main line of sight.