The promotive multi focus lenses which have urgent refracting power change

摘要

This invention, has had the main meridian of the promotion which passes by the distant apparent territory, the intermediate apparent territory, the Chikakata apparent territory and the aforementioned three territories, and the joining frequency which is equal to the difference of average spherical value with the Chikakata apparent territory datum point and the distant apparent territory datum point, it is something regarding the promotive multi focus spectacle lenses. As for the lens, it is defined, as vertical distance with the point and mounting center with respect to meridian of the place where just 85% of joining frequency values is larger than the average spherical value average spherical value in the distant apparent territory datum point it has possessed the promotive length under 12mm. In spite even in this short promotive length the lens excels in order to guarantee the efficiency where, multiplying the slope of spherical value in cylinder value, ratio with the product and the square of joining frequency which can, in all points in the 40mm diameter disk which centers the center of the lens, is under 0.08mm-1. Furthermore, cylinder value in the part of the disk which from mounting center is located on, is 0.5 times that joining frequency. These features in spite even in small promotive length, guarantee the optical efficiency of the lens.