Patent ID: 6779889
Filing Date: 2004-08-24
Classification: G02C

Abstract:
Spectacle lens comprisinga distance region designed for viewing at greater distances including infinity; a near region designed for viewing at shorter distances including reading distances; and a progression zone disposed between the distance portion and the near portion, in which a power of the spectacle lens increases from a value in a distance reference point located in the distance region to a value at a near reference point located in the near portion along a principal meridian line curving towards a nose; wherein for minimizing a change of imaging properties with horizontal movements of a gaze along a curve described by points of penetration of principal rays through a front surface, these principal rays passing though a point having the coordinates (xâˆ’dx, y, s) at the beginning of a movement and a point having the coordinates (x+dx, y, s) at the end of the movement, at s=âˆ’40 mm and dx=10 mm an absolute value of a difference between a minimum and a maximum astigmatism occurring along the curve is smaller than AH, which is a function of lens parameters x, y, Sph, and add, wherein the function is obtained by interpolating and extrapolating the values provided in the tables below: Sph = âˆ’4.0 dpt, add = 1.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.1720.106y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]0.5270.567Sph = âˆ’4.0 dpt, add = 2.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.4010.341y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]0.9981.202Sph = âˆ’4.0 dpt, add = 3.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.4900.384y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]1.6172.003Sph = 0.5 dpt, add = 1.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.1970.130y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]0.6670.727Sph = 0.5 dpt, add = 2.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.4130.353y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]1.0741.194Sph = 0.5 dpt, add = 3.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.5230.390y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]1.7082.030Sph = 5.0 dpt, add = 1.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.2050.135y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]0.7190.732Sph = 5.0 dpt, add = 2.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.4110.333y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]1.1921.330Sph = 5.0 dpt, add = 3.0 dpty = 15 mmx [mm]âˆ’15.015.0AH [dpt]0.6270.383y = âˆ’35 mmx [mm]âˆ’15.015.0AH [dpt]1.7722.271.