Patent ID: 8840246

Claim:
A method for determining an edge contour of an uncut spectacle lens and implemented by a computer programmed to perform the method, the method comprising: a spectacle frame data providing step, in which data defining the contour of the spectacle frame comprising the coordinates of n points P 1 , P 2 , . . . P n of the contour of the spectacle frame are provided, where n is an integer, a minimum edge thickness providing step, in which the minimum edge thickness Epmin of the uncut spectacle lens is provided, an initial contour providing step, in which is provided an initial contour Ci of the uncut spectacle lens comprising n points A i,1 , A i,2 , . . . A i,n , with j between 1, and n points A i,j , P j and the prism reference point O of the spectacle lens are aligned by the computer and OA i,j >OP j , a thickness determining step, in which the thickness Ep(A i,j ) of the uncut spectacle lens at point A i,j is determined by the computer, an optimized point selecting step, in which an optimized point A o,j is selected by the computer and wherein if the thickness Ep(A i,j ) of the uncut spectacle lens at point A i,j is greater or equal to the minimum edge thickness Epmin, A o,j =A i,j , if the thickness Ep(A i,j ) at point A i,j is smaller than the minimum edge thickness Epmin, the position of the optimized point A o,j along the radial direction between point Ai,j of the initial contour Ci and point P j of the contour of the spectacle frame is determined by the computer by an iterative process comprising I iterations so as to have |Ep(A o,j )−Epmin|≦ε, with Ep(A o,j ) the thickness of the uncut spectacle lens at point A o,j , and 0.001 mm≦ε≦Epmin/5, and if after I iterations, where I is an integer, no point A o,j having |Ep(A o,j )−Epmin|≦0.01 mm is determined, optimized point A o,j is selected by the computer between point A i,j and point P j , a repeating step, in which the thickness determining step and the optimized point A o,j selecting step are repeated j times, where j is between 1 and n, an edge contour determining step, in which the edge contour of the uncut spectacle lens delimited by the n optimized points is determined by the computer.