Method of and apparatus for processing peripheral edge of lens for spectacles

An apparatus for processing a peripheral edge of a lens to be ground, wherein said lens is to be fitted in a lens frame of a spectacle framework, said lens being rotatable about its rotational axis, said apparatus comprising:

• a disc-shaped measuring probe having a radius;
• a columnar grindstone having a radius, said grindstone being rotatable about its rotational axis;
• first moving means for moving said measuring probe along an inner periphery of said lens frame to measure a closed locus along which a center of said measuring probe moves;
• means for computing a plurality of circles having their respective centers located on said locus, each of said circles having a radius which is equal to a sum of the radius of said columnar grindstone and the radius of said measuring probe;
• means for computing a closed envelope by which outermost edge points of the respective circles are connected to each other in tangential relation to said outermost edge points;
• and
• second moving means for moving the rotational axis of said lens along said envelope relative to the rotational axis of said columnar grindstone to grind the peripheral edge of said lens, thereby forming a lens which is fitted in said lens frame.

An apparatus for processing a peripheral edge of a lens to be ground, wherein said lens is to be fitted in a lens frame of a spectacle framework, said lens being rotatable about its rotational axis, said apparatus comprising:

• a disc-shaped measuring probe having a radius;
• a columnar grindstone having a radius and rotatable about its rotational axis;
• means for moving said measuring probe along an inner periphery of said lens frame to measure a closed locus along which a center of said measuring probe moves;
• means for measuring a distance between an optical point within said lens frame and a center of said measuring probe;
• means for measuring an angle defined between a straight reference line passing through said optional point and a straight line passing through said optional point and the center of said measuring probe;
• first arithmetic means for computing a plurality of circles on the basis of said distance and said angle, said circles having their respective centers located on said locus, each of said circles having a radius which is equal to a sum of the radius of said columnar grindstone and the radius of said measuring probe;
• second arithmetic means for computing a closed envelope by which outermost edge points of the respective circles are connected to each other in tangential relation to said outermost edge points;
• control means for controlling said lens so as to move the rotational axis of said lens along said envelope relative to the rotational axis of said columnar grindstone;
• and
• means for holding said lens to rotate the same about its rotational axis, and for urging said lens against the rotating grindstone to grind the peripheral edge of said lens, thereby forming a lens which is fitted in said lens frame.