Patent ID: 8157618

Claim:
An eyeglass lens processing apparatus for processing a bevel in a peripheral edge of an eyeglass lens, the apparatus comprising: a data input unit ( 2 ) which obtains a shape data of a rim of an eyeglass frame; an edge position detecting unit ( 200 F, 200 R) which obtains edge positions of front and rear surfaces of the lens on the basis of target lens shape data obtained from the rim shape data; a bevel curve setting unit ( 50 , 5 ) which sets a bevel curve formed on the lens edge and includes an input unit ( 300 ) used to select the bevel curve substantially equal to a frame curve based on at least the rim shape data; a reference point setting unit ( 50 , 5 ) which sets first, second third and fourth points which are located on the lens edge and are used as a reference to obtain a bevel path, so that a line located on the target lens shape and passing through the first and second points intersects a line located on the target lens shape and passing through the third and fourth points; and a bevel path calculating unit ( 50 ) which: a) obtains a first plane including a bisection point of a first line connecting the first and second points and perpendicular to the first line; b) obtains a second plane including a bisection point of a second line connecting the third and fourth points and perpendicular to the second line; c) obtains an intersection line LO at which the first and second planes intersect each other; d) obtains a bevel spherical surface Sf so that a center of the bevel spherical surface Sf having a radius of the bevel curve set by the bevel curve setting unit is located on the intersection line LO and the bevel spherical surface Sf passes through a desired edge position; and e) obtains the bevel path on the basis of the target lens shape data and the obtained bevel spherical surface Sf.