US 12,228,803 B2
Computer implemented method of determining a base curve for a spectacle lens and method of manufacturing a spectacle lens
Markus Welscher, Rainau (DE); Helmut Wietschorke, Aalen (DE); Ralf-Roland Sauer, Hüttlingen (DE); and Christoph Winter, Hüttlingen (DE)
Assigned to Carl Zeiss Vision International GmbH, Aalen (DE)
Filed by Carl Zeiss Vision International GmbH, Aalen (DE)
Filed on Oct. 18, 2019, as Appl. No. 16/657,497.
Application 16/657,497 is a continuation of application No. PCT/EP2018/060324, filed on Apr. 23, 2018.
Application PCT/EP2018/060324 is a continuation of application No. 15/494,151, filed on Apr. 21, 2017, abandoned.
Prior Publication US 2020/0050020 A1, Feb. 13, 2020
Int. Cl. G02C 7/00 (2006.01); G02C 7/02 (2006.01); G02C 7/06 (2006.01)
CPC G02C 7/028 (2013.01) [G02C 7/02 (2013.01); G02C 7/027 (2013.01); G02C 7/063 (2013.01); G02C 2202/08 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A computer-implemented method of determining one base curve value or two base curve values representing a base curve for a front surface of a spectacle lens, the method comprising:
receiving frame data including frame rim data;
determining the one base curve value or the two base curve values for the front surface of the spectacle lens from the received frame data by:
calculating the one base curve value or the two base curve values from the received frame data by a fit of a freeform surface to be formed on the front surface to a curve, or to points of the curve, which represents the frame rim data,
wherein the one base curve value or the two base curve values are given by an average curvature of the freeform surface or a mean curvature of the freeform surface at a reference point;
varying a curvature of the back surface until a calculated power of the spectacle lens coincides with a prescribed power for correcting an ametropia of a wearer of the spectacle lens with the average curvature or the mean curvature of the freeform surface to be formed on the front surface; and
optimizing the freeform surface to be formed on the front surface by ray-tracing without changing the average curvature or the mean curvature, respectively, so that the front surface maintains the one base curve value or the two base curve values.