Abstract:
A system and method for coating an optical lens by, for example vapor deposition, that employs a housing or drum having a plurality of apertures that each receives a lens holder assembly. The lens holding assembly configured to hold a standard, uncut optical lenses or lens blanks or, alternatively, to hold cut, non-standard shaped and sized optical lenses.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/882,495 filed Sep. 25, 2013 entitled Ophthalmic Lens Holder For Physical Vapor Deposition, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the coating of optical lenses and, more particularly, to systems and methods for holding optical lenses during a lens coating process. 
       BACKGROUND OF THE INVENTION 
       [0003]    Anti-reflective coatings reduce reflections off the front and back surfaces of ophthalmic lenses and therefore are desirable for creating eyeglasses with improved light transmission, visibility, and aesthetics. Typically, these anti-reflective coatings must be applied as one or more layers having a precise and relatively thin thickness. In this respect, physical vapor deposition machines, such as sputtering box coaters, are often used for the coating application process. 
         [0004]      FIG. 1  is a plan view of a horizontally rotating drum  10  for holding a lens  22  for coating a surface  22 A of the lens  22  in a vertical orientation within an interior of a sputtering box or chamber. The drum  10  includes a plurality of sides  6  that are separated from each other by divider walls  4 . As shown in  FIG. 2 , each side  6  has a mounting fixture  8  onto which an item, for example the optical lens  22 , can be mounted for coating. 
         [0005]    In operation, an ophthalmic lens  22  is mounted to the fixture  8  via a double-sided adhesive pad or tape  20 . One drawback to this mounting style is that a backside  22 B of the lens  22  must be completely covered with an adhesive tape  20  or similar covering to prevent portions of the backside  22 B of the lens  22  from also being coated. Since this back covering must precisely and completely cover the backside  22 B surface of the lens  22 , the tape  20  can be time consuming to apply. Additionally, the adhesive nature of the double-sided adhesive pad  20  often prevents the tape  20  from being reused for the coating more than one lenses  22 . 
         [0006]    What is needed in the art is a drum and lens holder system that is more robust, reusable, and allows for a more efficient holding and exchange of lenses of varying shapes and sizes. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0007]    Lens holding systems and methods according to the present invention provide robust, reusable, and efficient holding and exchange systems for lenses of varying shapes and sizes during a coating process such as vapor deposition. These objectives are realized, in part, by providing a housing or drum having a plurality of apertures into which lens holders can be inserted and secured. 
         [0008]    The lens holders are configured to accept a single lens size and shape or, alternatively, configured to employ a system of spring arms that facilitate acceptance of a variety of lenses of different sizes and shapes. 
         [0009]    The housing or drum may be of a modular design that is formed of a plurality of individual drum segments that are held together by, for example, magnets. The housing and/or lens holder may be configured to present the lens for uniform coating across a surface of the lens or for a non-uniform, for example gradient, coating across a surface of the lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    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 
           [0011]      FIG. 1  is a plan view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0012]      FIG. 2  is an elevation view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0013]      FIG. 3  a plan view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0014]      FIG. 4  is an elevation view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0015]      FIG. 5  is a plan view of a lens holder fixture according to one embodiment of the present invention; 
           [0016]      FIG. 6  is a plan view of a lens holder fixture according to one embodiment of the present invention; 
           [0017]      FIG. 7  is a plan view of a lens holder fixture according to one embodiment of the present invention; 
           [0018]      FIG. 8  is a plan view of a lens holder fixture according to one embodiment of the present invention; 
           [0019]      FIG. 9  is an elevation view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0020]      FIG. 10  is an elevation view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0021]      FIG. 11  is a perspective view of a drum for a vapor deposition coater system according to one embodiment of the present invention; 
           [0022]      FIG. 12  is a plan view of a lens holder assembly according to one embodiment of the present invention; 
           [0023]      FIG. 13  is a cross-sectional view of a lens holder assembly according to one embodiment of the present invention; and, 
           [0024]      FIG. 14  is a plan view of a lens holder assembly according to one embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0025]    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. 
         [0026]    With reference to  FIGS. 3 and 4 , one embodiment of the present invention employs a housing or drum  100  having a plurality of divider walls  102  that extend from the intersections of a plurality of drum sides  106 . For example, the drum  100  may employ six sides  106 , as shown in  FIG. 4 , or as few as 2 drum sides  106 . The lens retaining system includes a spring clip ring  104  within which the lens  22  is retained or secured. The spring clip ring  104  is, in turn, secured to the drum  100  by guides  108  that are formed vertically within the divider walls  102 . The sides of the spring clip ring  104  slides within opposing guides  108 . In one embodiment, the guides  108  are, for example grooves, channels, or parallel raised lips formed within or on the surface of opposing sides of each divider wall  102 . Each guide  108  begins, for example at an upper most end of the walls  102  and extend downward. 
         [0027]    In one embodiment, the spring clip ring  104  includes a rigid framework formed of an outer portion  110  and a lens support portion comprising a plurality of spring-loaded arms  112  that are biased inward relative to the outer portion  110 . In this respect, the plurality of arms  112  apply opposing pressure against the edge or edges of the lens  22 , thereby securing the lens  22  in a removable arrangement. 
         [0028]    In one embodiment, the spring clip ring  104  is composed of a wire and has an internal diameter of about 82 millimeters and an external diameter of about 85 millimeters. The walls  102  have a height of, for example, about 85 millimeters and are spaced, for example, about 90 millimeters from each other. The guides  102  have a height of, for example, about 65 millimeters, a width of about 7 millimeters and a depth of about 7 millimeters. 
         [0029]    The spring clip ring  104  is sized such that its diameter is larger than the distance between the inner surfaces of two adjacent divider walls  102 , but smaller or nearly the same size as the distance between the interior surface of the opposing guides  108 . Hence, the spring clip ring  104  can be simultaneously slid into each guide  108 , starting at the upper, open ends of the guides  108  and rests upon the lower, closed end of the guide  108 . 
         [0030]    In one embodiment, each guide  108  is preferably located between the top of each divider wall  102  and a position about halfway down the vertical height of the wall  102 . In another embodiment, the guide  108  is located between the top of each divider wall  102  and any lower point that would maintain the spring clip ring  104  between the top and bottom of the divider walls  102 . In yet another embodiment, the guide  108  extends the entire length of the divider wall  102 , allowing the spring clip ring  104  to rest on a lower horizontal surface of the drum  100 . 
         [0031]    With reference to  FIGS. 5-9 , in another embodiment of the present invention, instead of employing spring clip ring  104  to attach the lens  22  to the drum  100 , a curved fixture  120  is employed to secure the lens  22  to the drum  100 . The fixture  120  is formed of an elongated rigid member having a generally ring, crescent, “C-shape,” or broken or incomplete-circle shape. The gap between ends of the fixture  120  is, for example, between 180 degrees and 0 degrees (i.e., a full circle). Alternatively, fixture  120  is formed of a non-circular or a crescent shapes, for example, in the shape of a square, rectangle or octagon. In certain embodiments, the fixture  120  is, for example, formed from a metallic wire having a diameter of about 78 millimeters and forms a ring shape having an overall diameter of about 85 millimeters. 
         [0032]    With reference to  FIG. 6 , in operation, a portion of a tape  122  having a single adhesive side for example, “surface saver” tape which is known in the ophthalmic lens industry, is adhered to one side of the fixture  120 . Any excess portions of the tape  122  extending beyond the sides of the fixture  120  are either trimmed or wrapped around the fixture  120 . As shown in  FIGS. 7 and 8 , the ophthalmic lens  22  is positioned against the adhesive side of the tape  122  such that one side is adequately covered by the tape  122  to prevent deposition coating onto the covered side of the lens  22 . 
         [0033]    As shown in  FIG. 9 , the fixture  120  is then slid into the channel guides  108  of two divider walls  102 , leaving one side of the lens  22  completely covered with tape  122  and the other side of the lens  22  completely exposed for vapor deposing of a coating, such as an anti-reflective coating. 
         [0034]    It should be understood that other connection and support mechanisms are contemplated for use in addition to or in alternative of guides  108 . For example, the spring clip ring  104  and the fixture  120  may employ hooks that engage openings or loops formed in or on the drum divider walls  4 . Additionally, it should be understood that the spring clip ring  104  and the fixture  120  may alternately employ attachment mechanisms that connects directly to the drum side  6 . For example, one or more hooks can be fixed to the drum side  6 , allowing the spring clip ring  104  and the fixture  120  to be supported or suspended by the spring ring outer portion  110  or the fixture  120 , respectively. 
         [0035]    In yet another embodiment according to the present invention, with reference to  FIGS. 10 and 11 , a drum  200  has, for example, six drum sides  204 . Each drum side  204  having a drum aperture  202  formed therein. In contrast to the previously described drums  10  and  100 , the drum  200  does not employ divider walls  4 ,  102 . In certain situations, omission of the divider walls  4 ,  102  is advantageous because it simplifies fabrication of the drum and ultimately provides for a more robust drum. 
         [0036]    Formed within the drum aperture  202  is a drum aperture lip  208  that has a diameter that is slightly reduced from the diameter of the drum aperture  202 . Formed on a surface of the aperture lip  208  are drum magnets  220 . A difference in a diameter of the drum aperture lip  208  and a diameter of the aperture lip  208  represents a width of the drum aperture lip  208 . 
         [0037]    The drum  200  is, for example, of a modular design employing a plurality of drum segments  206 , for example  3  drum segments  206  combine to from the completely assembled drum  200 . The drum segments  206  may be formed of a plastic or metallic material. The drum segments  206  are secured to one another by employing a system of corresponding magnets on the surfaces of the segments  206  that are intended for mating against an adjacent segment  206 . This configuration advantageously allows for easier disassembly of the drum  200  for accessing an interior of the drum  200  for cleaning, maintenance, and repair. 
         [0038]    In order to secure the lens  22  to the drum  200  a lens holding assembly  210  is employed. The lens holding assembly  210 , shown in  FIGS. 12 and 13 , has an annular or ring shape forming a lens aperture  212 . The assembly  210  may be formed of a plastic or metallic material. The lens aperture  212  is sized to receive a fixed shape lens  22 , such as an uncut semi-finished lens. Formed within the lens aperture  212  is a retaining lip  214  that has a diameter that is slightly reduced from a diameter of the lens aperture  212  and a diameter of the lens  22 . 
         [0039]    A width of the lens holding assembly  210 , i.e. a minimum distance from an exterior surface of the annular assembly  210  to the interior surface of the lens aperture  212  may but need not be approximately equal to the width of the drum aperture lip  208 . 
         [0040]    On a backside  216  of the holder assembly  210  are holder magnets  218 . The holder magnets  218  may form a surface or a portion of a surface of the backside  216  of the holder assembly  210 . In embodiments in which the holder assembly  210  is formed of a plastic, the magnets  218  may be inserted and secured within holes formed in the surface of the backside  216 . In embodiments in which the holder assembly  210  is formed of a metallic material, the metallic material may function as the magnet  218 . 
         [0041]    With reference to  FIG. 13 , in operation, the lens  22  is slid into the lens aperture  212  from the backside  216  of the holder assembly  210  until the surface  22 A of the lens  22  to be coated abuts the retaining lip  214 . Once in position, the lens  22  will occupy an approximate entirety of the area of the aperture  212 . The holder assembly  210  loaded with a lens  22  is then inserted into the drum aperture  202 . The holder assembly  210  is secured or held within the drum aperture  202  by the attraction of the magnets  218  of the holder assembly  212  and the drum magnets  220 . It is also noted that by using this holder assembly  210 , the backside  216  of the lens  22  is protected from any overspray of the coating deposition, as described above. 
         [0042]    In order to prevent the lens  22  from falling towards and/or out from the backside  216  of the aperture  212  and into the interior of the drum  200 , a backstop  222  is employed at each of the drum apertures  202  of the drum  200 . With reference to  FIGS. 10 and 11 , the backstop  222  is secured within the interior of the drum  200  so as to be reversibly biased or spring loaded in an outwardly direction through a corresponding drum aperture  202 . One or more portions  224  of the backstop  222  may project outward from the interior of the drum  200  to and/or through a plane defined by the circumference of the drum aperture  202 . 
         [0043]    In operation, as the holder assembly  210  loaded with the lens  22  is inserted into the drum aperture  202 , the one or more portions  224  of the backstop  222  will contact a surface  22 B of the lens  22  and prevent the lens  22  from falling from the backside  216  of the aperture  212  and into the interior of the drum  200 . However, as the attraction of the magnets  218  of the holder assembly  212  and the drum magnets  220  pull and secure the holder assembly  210  within the drum aperture  202 , the spring loaded backstop  222  deflects in a direction towards an interior of the drum  200 . Alternatively stated, the attractive force of the magnets  218  of the holder assembly  212  and the drum magnets  220  is greater than the counter force applied to the surface  22 B of lens  22  by the backstop  222 . 
         [0044]    In certain embodiments of the present invention, the backstop  22  is in the form of a linear beam positioned and secured within the drum  200  so as to span across a portion of the corresponding drum aperture  202 , as shown in  FIGS. 10 and 11 . The one or more portions  224  of the backstop  222  may be in the form of two projections that extend outward from the backstop  222  positioned within the interior of the drum  200  to and/or through a plane defined by the drum aperture  202 . It should be understood that other forms of the backstop  222  and portions  224  may also be employed depending, in part, on the shape and size of the lens  22  being coated. 
         [0045]    In another embodiment of the present invention, in order to secure the lens  22  to the drum  200  a lens holding spring assembly  240  is employed. The lens holding spring assembly  240 , shown in  FIG. 14 , has an annular or ring shape with a lens aperture  242  formed therein. The assembly  240  may be formed of a plastic or metallic material. Within the lens aperture  242  are a plurality of spring arms  244  that are biased inward to an interior of the lens aperture  242 . The lens holding assembly is advantageous for the securing and coating of lenses of varying or non-standard shapes and sizes, for example, cut ophthalmic lenses. In this respect, the plurality of arms  244  apply opposing pressure against the edge of the lens  22 , thereby securing the lens  22  within the assembly  240  in a removable arrangement. 
         [0046]    A width of the lens holding assembly  240 , i.e. a minimum distance from an exterior surface of the annular assembly  240  to the interior surface of the lens aperture  242 , may but need not be approximately equal to the width of the drum aperture lip  208  previously described. 
         [0047]    On a backside  246  of the holder assembly  240  are assembly holder magnets  248 . The assembly holder magnets  248  may form a surface or a portion of a surface of a backside  246  of the holder assembly  240 . In embodiments in which the holder assembly  240  is formed of a plastic, the magnets  248  may be inserted and secured within holes formed in the surface of the backside  246 . In embodiments in which the holder assembly  240  is formed of a metallic material, the metallic material may function as the magnet  248 . 
         [0048]    In operation, the lens  22  is inserted between the spring arms  244 . The holder assembly  240  loaded with a lens  22  is then inserted into the drum aperture  202 . The holder assembly  240  is secured or held within the drum aperture  202  by the attraction of the magnets  248  of the holder assembly  240  and the drum magnets  220 . 
         [0049]    In order to prevent the backside  22 B of lens  22  from accidental coating by coating material entering the interior of the drum  200  through the annular space between the lens  22  and the interior surface of the lens aperture  242 , an assembly backing may be employed. The assembly backing may be in the form of a rigid or semi-rigid material, for example a plastic or metallic sheet or foam board, that is positioned between the lens  22  being held within the assembly  240  and the backstop  222  of the drum  200 . Alternatively, the backstop  222  of the drum  200  may be omitted and the backing may be in the form of plastic wrap or a single sided adhesive, for example “surface saver” that is wrapped over the backside  246  of the lens holder assembly  240  prior to insertion of the assembly into the drum aperture  202 . 
         [0050]    While the above-described drums  100  and  200  have been shown in the figures as employing sides and drum apertures that present the surface  22 A of the loaded lens  22  to a coating system or devise in a substantially perpendicular orientation relative to drum bottom  105  and  205 , respectively, in certain embodiments of the present invention, it may be desirable to employ a drum  100  or  200  that orients the surface  22 A of the loaded lens  22  in an orientation relative to drum bottom  105  and  205  that is substantially non-perpendicular. Such circumstances may arise, for example, when it desirable to apply a coating on the surface  22 A of the loaded lens  22  that varies from one side the surface  22 A to the other. 
         [0051]    In certain embodiments of the present invention, a substantially non-perpendicular orientation of the surface  22 A of the loaded lens  22  is achieved by varying the angle of the sides  106  of the drum  100  or the sides  204  of the drum  200 . In such embodiments, the non-perpendicular orientation of the sides  102  of the drum  100  or the sides  204  of the drum  200  may be either static or adjustable. 
         [0052]    In certain embodiments of the present invention, a substantially non-perpendicular orientation of the surface  22 A of the loaded lens  22  is achieved by varying the angle of the drum aperture  202  relative to the sides  204  of the drum  200 . In certain other embodiments of the present invention, a substantially non-perpendicular orientation of the surface  22 A of the loaded lens  22  is achieved by varying the angle of the lens aperture  212  of the lens holding assembly  210  relative to the sides  204  of the drum  200 . 
         [0053]    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.