Patent ID: 8523353

Claim:
A method of calculating a shape of a longitudinal profile of an engagement ridge or groove ( 28 ) for machining on the edge face ( 23 ) of an ophthalmic lens ( 20 ) in order to enable the ophthalmic lens to be engaged into a bezel or onto a ridge of an eyeglass frame, the method comprising: an operation of acquiring with an outline-reader appliance ( 100 ) a shape of an initial longitudinal profile ( 29 ); an operation of prepositioning said initial longitudinal profile ( 29 ) in a coordinate system tied to the ophthalmic lens ( 20 ); an operation of searching for two remarkable points (Pr 1 , Pr 2 ) of said initial longitudinal profile ( 29 ), which points are distinct from each other, said operation comprising: a) acquiring a plurality of characteristics relating to the ophthalmic lens ( 20 ) or to the initial longitudinal profile ( 29 ); b) determining whether any of said acquired characteristics satisfies a decision criterion, by comparing the value of said acquired characteristic with a predetermined threshold value; c) selecting the first remarkable point (Pr 1 ) from a first list of points of said initial longitudinal profile ( 29 ) as being the point at which one of said acquired characteristics satisfies a first positioning criterion, said first positioning criterion being selected as a function of the result of step b); and d) selecting the second remarkable point (Pr 2 ) from a second list of points of said initial longitudinal profile ( 29 ), as being the point at which one of said acquired characteristics satisfies a second positioning criterion, said second list being deduced from the result of step c); an operation of correcting the position of each remarkable point (Pr 1 , Pr 2 ) along an axial direction (Z 1 ) substantially perpendicular to a mean plane of the ophthalmic lens ( 20 ); and an operation of calculating with a control unit ( 400 ) the three-dimensional shape of a final longitudinal profile ( 29 ′) in the coordinate system of the ophthalmic lens ( 20 ), resulting from a geometrical transformation of the initial longitudinal profile ( 29 ) that is such as to cause the final longitudinal profile ( 29 ′) to pass via the first and second remarkable points (Pr 1 , Pr 2 ) as modified during the preceding operation.