| 摘要 |
PURPOSE:To prevent the occurrence of blur due to prism phenomenon to improve the practicability by forming a padded lens for close distance on the outside curved surface of a lens for far distance and reducing gradually the height of a zone just under the lens for close distance and connecting this zone and the lens part for distance by progressive bands. CONSTITUTION:A padded lens 11 for close distance having a prescribed height is formed on the outside curved surface of a lens 10 for far distance, and its optical center is set to a point P, and an outside curved lens part 10a in the zone just under the lens 11 is formed into an arcuate surface and has the height reduced gradually. Since the lens 11 for close distance and the lens part for far distance other than the part 10a are connected to progressive bands, there is not boundary lines between parts for far distance and close distance and prism phenomena do not occur in progressive bands. Consequently, the sight ins not interfered by a blur part even in case of the side way sight, and the multifocus function based on progressive bands is obtained to attain a high practicability.
|
