Method and Apparatus for the Dry Release of a Compliant Opthalmic Article from a Mold Surface

Abstract

An apparatus for releasing a molded lens from a deformable mold includes a shear ring for temporarily retaining an annular portion of the deformable mold outside a periphery of the lens and a plunger for deforming an annular section of the deformable mold within the periphery of the lens. The apparatus can be employed to release a non-hydrated hydrogel lens from a deformable mold section.

1 . A method for releasing an ophthalmic molded lens from a mold cavity of a deformable mold, the deformable mold having an anterior molding surface and an opposite curved posterior surface, the method comprising: 
 a) distorting the anterior molding surface by 
 i) pressing against the curved posterior surface along a first annulus; and  
 ii) pressing against the anterior molding surface along a second annulus comprising a shear ring;  
   b) the first and second annuli being generally concentric with the molded lens with the first annulus being within a perimeter of the molded lens and the second annulus being radially spaced from the perimeter of the molded lens; and    c) the distorting of the molding surface creating sufficient shear between the molded lens and the molding surface to effect a peeling of the molded lens from the molding surface.    
     
     
         2 . The method of  claim 1 , wherein the peeling progresses radially inward from the perimeter of the molded lens.  
     
     
         3 . The method of  claim 1 , wherein pressing against the curved posterior surface is continuous along the first annulus.  
     
     
         4 . The method of  claim 1 , further comprising forming the first annulus of a rounded surface.  
     
     
         5 . The method of  claim 1 , wherein pressing against the curved posterior surface is intermittent along the first annulus.  
     
     
         6 . The method of  claim 1 , wherein pressing against the anterior molding surface is continuous along the second annulus.  
     
     
         7 . The method of  claim 1 , wherein pressing against the anterior molding surface is intermittent along the second annulus.  
     
     
         8 . The method of  claim 1 , further comprising forming the shear ring to include a knife edge.  
     
     
         9 . The method of  claim 8 , further comprising forming the knife edge from facets intersecting at an acute included angle.  
     
     
         10 . The method of  claim 8 , further comprising forming the knife edge from facets intersecting at an obtuse included angle.  
     
     
         11 . The method of  claim 1 , further comprising hydrating the molded lens after peeling of the molded lens from the molding surface.  
     
     
         12 . The method of  claim 1 , further comprising releasing an ophthalmic molded lens having a hydrated modulus less than 70 gm/mm 2 .  
     
     
         13 . A method for releasing a compliant hydrogel molded lens from a concave mold surface of a deformable mold comprising deforming the mold in a manner that creates a shear force between the concave surface and the molded lens sufficient to effect the peeling of the molded lens from the concave mold surface wherein the peeling starts at an outer periphery of the molded lens and propagates to a center of the molded lens.  
     
     
         14 . The method of  claim 13 , further comprising hydrating the molded lens after peeling.  
     
     
         15 . The method of  claim 13 , further comprising releasing the molded lens from the concave mold surface prior to initially hydrating the lens.  
     
     
         16 . The method of  claim 13 , further comprising deforming the mold by fixing a portion of the deformable mold spaced radially beyond a periphery of the molded lens and deforming the concave mold surface to peel a portion of the molded lens from the deformable mold.  
     
     
         17 . The method of  claim 13 , further comprising continuously propagating the peeling from the outer periphery of the molded lens to the center of the molded lens.  
     
     
         18 . A method of releasing a molded ophthalmic lens having a periphery from a deformable mold section, the deformable mold section having concave anterior mold surface and a corresponding curved posterior surface, the method comprising confining a portion of the deformable mold section radially spaced beyond the periphery of the molded ophthalmic lens and deforming the deformable mold inside the periphery of the molded ophthalmic lens to induce separation of the molded ophthalmic lens from the deformable mold section.  
     
     
         19 . The method of  claim 18 , further comprising hydrating the molded ophthalmic lens after separation from the deformable mold section.  
     
     
         20 . The method of  claim 18 , wherein confining a portion of the deformable mold section includes contacting an exposed surface of the portion of the deformable mold section with a shear ring.  
     
     
         21 . The method of  claim 18 , wherein confining the portion of the deformable mold section includes contacting the exposed surface of the portion of the deformable mold section with a knife edge.  
     
     
         22 . Apparatus for releasing a molded ophthalmic lens from a mold cavity of a deformable mold having an anterior molding surface and an opposite curved posterior surface, the apparatus comprising: 
 a) a plunger having an end face and rounded surface raised from the end face for pressing against the curved posterior surface in an annulus smaller in diameter than the lens; and    b) a female section having a recess for receiving the deformable mold, the female section including a shear ring edge extending into the recess for pressing against the anterior surface in an annulus greater in diameter than the lens.    
     
     
         23 . The apparatus of  claim 22 , wherein the molded ophthalmic lens has a hydrated modulus less than 70 gm/mm 2 .  
     
     
         24 . The apparatus of  claim 22 , wherein the shear ring is a knife edge.