Progressive Power Lens Saddle Part Thickness Reduction
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Solution Overview
Problem
Progressive power lenses with a both-sides composite progressive structure face the challenge of thicker lens thickness due to deeper surface refractive power in the object side surface, compromising outer appearance and fashion performance.
Innovation Solution
Incorporating a saddle-like part on the eyeball side surface with opposite signs of surface refractive power in the vertical and horizontal directions, reducing the lens curve depth while maintaining the meniscus shape, and applying aspherical surface correction to minimize optical characteristic deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a both-sides composite progressive structure is adopted with power change divided between front and rear surfaces, then the advantages of reduced eyeball swing angle and suppressed magnification difference are obtained, but the lens thickness increases due to deeper surface refractive power
Solution Approach 1:
The patent applies parameter changes by modifying the surface refractive power distribution between the front and rear surfaces. Specifically, it adjusts the sharing rates of power change in vertical and horizontal directions to optimize the balance between optical performance and lens thickness. The patent introduces specific mathematical relationships (DHf+DHn=ADD/2 and DHn-DHf≤ADD/2) to control the surface refractive power parameters, thereby reducing lens thickness while maintaining optical effectiveness.
2Reliability
If the lens curve depth of the object side surface is increased to maintain meniscus shape and achieve desired addition power, then the progressive power function is maintained, but the lens thickness increases further
Solution Approach 1:
The patent applies local quality by differentiating the treatment of vertical and horizontal power changes across different regions of the lens surfaces. It assigns different sharing rates for power change in vertical direction versus horizontal direction, allowing optimized local control of surface refractive power. This enables the lens to maintain progressive power function in critical areas while reducing overall lens thickness through localized power distribution adjustments.
Data Source
Figure 1A~2
Figure 3
Figure 4A~4C
AI summary
Provided is a progressive power lens (1) including: an object side surface (2); an eyeball side surface (3); and at least a near portion (12) having a power for near vision, characterized in that the object side surface (2) includes a power change in a vertical direction of the lens having a progressive refractive power function, the eyeball side surface (3) includes a power change in a horizontal direction of the lens having the progressive refractive power function, when a surface refractive power in the horizontal direction is defined as DHn and a surface refractive power in the vertical direction is defined as DVn in a near power measurement point N in the object side surface (2), a relational expression of DHn < DVn is fulfilled, and the near portion of the eyeball side surface (3) has a shaped part (14) in which the signs of positive and negative of a surface refractive power in the vertical direction of the lens and a surface refractive power in the horizontal direction of the lens are opposite to each other.