| 摘要 |
PROBLEM TO BE SOLVED: To provide an aspheric spectacle lens of which the upper and lower portions have performance suitable to farsight and nearsight, respectively, and of which the optical performance is superior even when the lens includes astigmatic refractive power. SOLUTION: In a spectacle lens which has a pair of refractive surfaces of an outer surface and an inner surface and of which the inner surface is a non-rotation symmetric aspheric surface, when the normal line of the inner surface erected at a frame insertion reference point is defined as a z<SB>2</SB>axis, a direction which becomes upper within the plane orthogonal to the z<SB>2</SB>axis in use of the spectacle is defined as a y<SB>2</SB>axis, and a direction orthogonal to the y<SB>2</SB>axis and the z<SB>2</SB>axis in a left-hand coordinate system is defined as an x<SB>2</SB>axis, and when the curvature at the height h [mm] from the z<SB>2</SB>axis of a line of intersection of the plane forming an angleθ[°] with the x<SB>2</SB>axis inclusive of the z<SB>2</SB>axis and the inner surface is expressed as C<SB>2</SB>(h,θ), within the range satisfying 10≤h≤20, 30≤θ≤150, the condition C<SB>2</SB>(h,θ+180)-C<SB>2</SB>(h,θ)>0 is satisfied when the lens is a minus lens, and the condition C<SB>2</SB>(h,θ+180)-C<SB>2</SB>(h,θ)<0 is satisfied when the lens is a plus lens. COPYRIGHT: (C)2004,JPO&NCIPI
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