Abstract:
A thin ophthalmic lens stabilized through incorporation of flange around all or a portion of a perimeter of the thin lens.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 62/029,355 filed Jul. 25, 2014 entitled Stabilized Thin Lens, incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present application relates to optical lenses and, more particularly, molded optical lenses formed with a stabilizing feature that prevents warping of the lens after formation. 
       BACKGROUND OF THE INVENTION 
       [0003]    Relatively thin, optical lenses, such as lenses ranging from 0.5 millimeters to 3.0 millimeters in thickness, are common in the market place, however, there are several challenges to the production of such lenses. For example, in certain circumstances, relatively thin, polymeric optical lenses tend to warp or otherwise lose their intended form when removed from the lens mold in which they were formed. 
         [0004]    This problem is exacerbated in the case of thin, polarized, polymeric optical lenses. Polarized optical lenses are commonly produced by incorporating an absorptive polarizer formed by stretching a sheet of, for example, polyvinyl alcohol having iodine doping, into or on a base lens substrate. When a thin polymeric lens incorporating such a polarizer is removed from the lens mold, the stretched sheet attempts to regain its un-stretch form and thereby pulls and deforms the formed lens out of the lens&#39;s intended shape. This deformation can result in a lens having a “potato chip-like” or “saddle” shape. Lenses exhibiting such deformation are typically not acceptable in the market place.  FIG. 1A  is an example of such a deformed molded lens and  FIG. 1B  is an example of a non-deformed molded lens. 
         [0005]    In order to overcome this problem, manufactures may attempt to cool the molded lenses within the mold for increased amounts of time in the hope of achieving increased lens stability at decreased temperatures. However, this technique has the obvious disadvantage of decreasing throughput of lens production. 
         [0006]    What is needed in the art is a more effective means for stabilizing the molded form of a thin, polymeric lens after molding that does not impact production throughput. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0007]    The present invention provides an effective means for stabilizing a thin polymeric lens such that, after molding or formation, the thin polymeric lens will maintain the intended molded form and/or geometry. This objective is achieved through the formation of a flange around all or a portion of a perimeter of the thin lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which: 
           [0009]      FIG. 1A  is a perspective view of a deformed thin molded lens. 
           [0010]      FIG. 1B  is a perspective view of a non-deformed thin molded lens. 
           [0011]      FIG. 2A  is a perspective view of a flanged, thin, molded lens according to one embodiment of the present invention. 
           [0012]      FIG. 2B  is a perspective view of three flanged, thin, molded lenses according to one embodiment of the present invention. 
           [0013]      FIG. 3  is a plan view of a pair of flanged, thin, molded lenses according to one embodiment of the present invention. 
           [0014]      FIG. 4  is a side elevation view of a flanged, thin, molded lens according to one embodiment of the present invention. 
           [0015]      FIG. 5  is a perspective view of a pair of flanged, thin, molded lenses according to one embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0016]    Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
         [0017]    The present invention provides an effective means for stabilizing a thin polymeric lens such that, after molding or formation, the thin polymeric lens will maintain the intended molded form or geometry. With reference to  FIGS. 2A through 5 , these objectives are, in part, achieved by molding the thin polymeric lens  10  such that the lens is formed with a stabilizing rim or flange  12  around the perimeter  14  of the molded lens  10 . 
         [0018]    The present invention is not limited by the polymeric material employed to form the thin lens  10 . The polymeric substrate or material may be a thermoset material or a thermoplastic material. With respect to thermoset materials, the substrate may include polymers from diethylene glycol bis (allyl carbonate) or diallyl diglycol carbonate, such as CR-39® from PPG, or Akzo Nobel brands NS205, NS200 and NS207. The lens substrate may also comprise other thermoset materials such as polymers of 1,3 butylene glycol dimethacrylate, acrylonitrile, allyl methacrylate, ethoxymethyl methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate; ally esters; co-polymers of allyl esters with styrene or vinyl type monomers, such as diallyl maleate, diallyl phthalate, methallyl methacrylate, and high index copolymers containing, e.g., vinyl functionality, isocyanates, urethanes, sulfur-containing aromatic vinyl compounds, and bromine-containing aromatic acrylic compounds. 
         [0019]    With respect to thermoplastic materials, the substrate may comprise polycarbonate resin such as that sold by Teijin, Sabic, and Bayer, Inc. of Pittsburgh, Pa. under various tradenames. The lens substrate may also comprise other thermoplastic materials such as polyamides, polystyrenes, polysulphones, mixtures of polycarbonate and polyurethanes, polyesters, polysulfones, polystyrenes, amorphous polyolefins, and acrylics. 
         [0020]    In certain embodiments of the present invention, as shown in  FIG. 2A , the lens  10  is tinted or colored by including a dye or tinting agent within the lens substrate. 
         [0021]    In certain embodiments of the present invention, the lens  10  is formed with a functional film or laminate incorporated within or on a front surface  16  or a back surface  18  of the thin lens  10 . In certain embodiments, the functional laminate or film is incorporated solely within the perimeter  14  of the thin lens  10  and is not incorporated into the area of the flange  12 . Alternatively, in certain embodiments, the functional laminate or film is incorporated within the area of the thin lens  10  as well as within all or a portion of the area of the flange  12 . The functional attributes of the functional laminate may include, for example, tinting or coloration, anti-reflection, anti-fogging, hard coating, polarization, photochromism, and easy-cleaning. 
         [0022]    In certain embodiments of the present invention, the thin lens  10  has an approximately uniform thickness between the front surface  16  and back surface  18  of 0.8 to 2.5 millimeters. In certain other embodiments of the present invention, the thin lens  10  has a non-uniform thickness between the front surface  16  and back surface  18  that ranges from approximately 0.8 to 2.5 millimeters. 
         [0023]    In certain embodiments, the thin lens  10  of the present invention has a circular perimeter  14 . The present invention is not limited by a diameter  20  of the thin lens  10 . In certain embodiments, the diameter  20  of the thin lens  10  is approximately 65 to 85 millimeters. In certain embodiments, the diameter  20  of the thin lens  10  is approximately 75 millimeters. 
         [0024]    In certain embodiments of the present invention, the flange  12  is formed uniformly or symmetrically around the perimeter  14  of the thin lens  10 . For example, if the thin lens  10  has a circular form or perimeter  14 , the flange  12  may also have a circular perimeter  22 . In certain embodiments, a width of the flange  12  from the lens perimeter  14  to a perimeter  20  of the flange  12  is approximately 5 to 20 millimeters. For example, in the case of a thin lens  10  having a circular form and a diameter 20 of 75 millimeters and a symmetrical flange  12  having a diameter of 87.9 millimeters attached thereto, a width of the flange  12  would be approximately 12.9 millimeters. 
         [0025]    Alternatively, in certain embodiments, the flange  12  is formed asymmetrically around the perimeter  14  of the lens  10 . Alternatively stated, the width of the flange  12  from the lens perimeter  14  to a perimeter  20  of the flange  12  is not substantially constant and is variable. 
         [0026]    In certain embodiments of the present invention, the flange has a thickness between a back surface  24  of the flange  12  and a front surface  26  of the flange  12  of approximately 0.5 to 3 millimeters. In certain embodiments, the thickness of the flange  12  will be less than a thickness of the lens  10  at perimeter  14 . In certain embodiments, the thickness of the flange  12  will be greater than a thickness of the lens  10  at perimeter  14 . 
         [0027]    In certain embodiments of the present invention, the entire flange  12  is positioned within a plane that is the same as or parallel to a plane in which the lens  10  resides or the same as or parallel to a plane that represents a best fit plane through the lens  10 . Alternatively, in certain embodiments of the present invention, the flange  12  is in a different, non-parallel plane than the plane in which the lens  10  resides or a different, non-parallel plane than a plane that represents a best fit plane through the lens  10 . 
         [0028]    In certain embodiments of the present invention, the interface or attachment point of the perimeter  14  of the lens  10  and the flange  12  forms a non-zero degree angle. 
         [0029]    The flange  12  is formed, for example, during molding or casting of the lens  10  in a flanged or flangeless mold or cast set-up. The flange  12  may be formed of the same material or substrate as the lens  10 , for example the flange  12  may be formed of polycarbonate. Alternatively, in certain embodiments of the present invention, the flange  12  is formed of a different material than that used to form the thin lens  10 . 
         [0030]    In practice, the flange  12  may be removed from the molded lens during processing of the thin lens  10 . Alternatively, the thin lens  10  may be process without removing the flange  12 . This may advantageously assist in protecting and maintaining the geometry of the thin lens  10  up to the point that the lens  10  associated with a lens frame of other structure that may assist in maintaining the geometry of the thin lens  10 . 
         [0031]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.