Progressive Addition Lens Astigmatism Distribution
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Solution Overview
Problem
Current progressive addition lenses face challenges in expanding the clear visual field range due to inherent astigmatism and distortion, particularly in the intermediate and near portions, where refractive power changes occur, and existing design methods are complex and inefficient.
Innovation Solution
Intentionally adding transmission astigmatism to the intermediate and near portions, including the meridian and main line of sight, while maintaining a higher horizontal refractive power than vertical refractive power after astigmatism correction, to mitigate sharp changes in astigmatism and expand the clear visual field range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transmission design is used to reduce intrinsic astigmatism and distortion, then visual clarity is improved, but the design process becomes complex and time-consuming
Solution Approach 1:
The patent performs preliminary ray tracing calculations during the design phase to determine target distributions of transmission refractive power and transmission astigmatism. By pre-calculating the ideal optical parameters before manufacturing, the complex transmission design process is simplified into a more straightforward manufacturing process while maintaining high visual clarity standards.
2Manufacturing precision
If astigmatism is minimized along the meridian, then distance and near vision are improved, but intrinsic astigmatism and distortion increase in other areas
Solution Approach 1:
The patent changes the approach from minimizing astigmatism to intentionally adding transmission astigmatism as a design parameter. By controlling the distribution of transmission astigmatism across different lens zones (distance, intermediate, near portions), the patent achieves better overall visual performance while managing intrinsic astigmatism through calculated additions rather than simple minimization.
Solution Approach 2:
The patent applies different astigmatism characteristics to different local zones of the lens. The transmission astigmatism distribution is specifically tailored for each portion (distance, intermediate, near) based on ray tracing calculations, allowing each zone to have optimized optical properties suited to its specific viewing function.
3Area of stationary object
If clear visual field range is expanded, then visual comfort is improved, but astigmatism control becomes more difficult
Solution Approach 1:
The patent uses ray tracing calculations to create a target model of ideal transmission refractive power and transmission astigmatism distributions. This target model serves as a blueprint that guides the lens design and manufacturing process, allowing the clear visual field range to be expanded while maintaining astigmatism control through reference to the pre-calculated optimal distribution patterns.
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 approach allows for a wider clear visual field range with transmission astigmatism of 0.50 D or less, incorporating the meridian and main line of sight, and reduces intrinsic astigmatism, thereby improving visual clarity and comfort for spectacle wearers.
Implementation Method 1
a progressive addition lens is a lens that has, as an area, a portion of a lens provided in an upper portion of the figure and having a refractive power to view a distance object, that is, a distance portion having a refractive power used for distance vision
Data Source
AI summary
A progressive addition lens and the related technology, the progressive addition lens including a near portion for viewing a near distance, a distance portion for viewing a distance farther than the near distance, and an intermediate portion between the near portion and the distance portion and having a progressive refraction function, in which the transmission astigmatism is added to the near portion and the intermediate portion of the distance portion, the near portion, and the intermediate portion, and in the near portion and the intermediate portion to which the transmission astigmatism is added, the progressive addition lens further includes a portion where an amount of horizontal refractive power is greater than an amount of vertical refractive power after subtracting the refractive power for astigmatism correction.