Apparatus and method for making cast ophthalmic lenses
AssigneeAmerican Optical Corporation
InventorsPeter R. Ramirez, Bradford Canterbury
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Abstract
Cast multifocal lenses are produced from ledged casting pieces molded from a master die having a molding surface made up of juxtapositioned die components each precision surfaced to a curvature and finish corresponding to a multifocal surface desired to be cast upon a lens and relatively prearranged according to desired height and position of cast lens ledging.
Claims14
A molding die for making plastic casting pieces having ledged surfaces of particular curvature and relative juxtaposition according to multifocal lens focal field surfaces desired to be produced on ophthalmic lenses cast in said plastic pieces, said molding die comprising:
- a base;
- a pair of tightly juxtapositioned die pieces having adjoining curved molding surfaces together forming a molding face of said die, one of said molding surfaces being of shorter radius of curvature than the other, said difference of surface curvatures producing a ledge extending at least partially across said molding face of said die;
- means for securing said die pieces to said base;
- and
- means for shimming at least one of said die pieces on said base for adjustment of height of said ledging across said molding face.
The method of making a ledged lens casting piece comprising the steps of:
- forming first and second master die components each having a finished curved surface and respectively adjoining finished sides, said surface of one of said components being of greater radius of curvature than the other;
- juxtapositioning said components by joining said surfaces thereof to form a composite molding face, said difference in curvatures of said surfaces of said components causing a portion of one of said finished sides to form a ledge across at least a portion of said molding surface;
- and
- molding a lens casting piece of plastic material against said molding face into which lenses may be subsequently cast.
Dependencies are inferred from the claim text.