Patent ID: 7341344
Filing Date: 2008-03-11
Classification: G02C

Abstract:
1. A progressive power lens having a positive vertex power in a distance portion, at least a back surface of the progressive power lens being configured as a progressive surface, given that an axis normal to a front surface of the progressive power lens at a prism reference point is defined as a z-axis, an axis which passes through an intersection of the z-axis and the back surface in a vertical direction in a state where the progressive power lens is worn by an wearer is defined as an y-axis, a sag amount which is a distance between a point on a curve, defined as an intersection line of the back surface and an y-z plane, at a height y and the y-axis is represented by z where a direction headed from the front surface to the back surface is defined as a positive direction of the z-axis, and a direction heading for an upper end of the progressive power lens along the vertical direction in a state where a wearer wears the progressive power lens is defined as a positive direction of the y-axis.