| 摘要 |
PROBLEM TO BE SOLVED: To provide a progressive refractive power lens which is, particularly, worn mainly for viewing a short-distance object to an intermediate-distance object, and can be designed so that a long-distance object located not so far, such as 3 to 5 m away, is seen comparatively easily. SOLUTION: The progressive refractive power lens includes a far-sight area, a near-sight area and a progressive area which is arranged between the two areas and where refractive power is changed progressively. The participating gradient (D), degree of participation (ADD) and length (L) of a progressive band are represented by D=ADD/L, and the participation gradient is set so that the degree of participation is gradually added, from the far-sighted area to the near-sighted area. Meanwhile in the lens, the entire length of the progressive band is set larger than 19 mm, while the participation gradient in the lower area of the progressive area, at least leading to the near-sighted area is represented by D=ADD/λ(λis defined as the length of the specific progressive band:λ≤19 mm); and more preferably, the participation gradient of the upper area of the progressive area is set smaller than that of the lower area. COPYRIGHT: (C)2008,JPO&INPIT
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