Abstract:
A method and a device for mounting eyeglass lenses, wherein branches and a bridge are connected by plastics material filaments engaged in peripheral grooves in the lenses and having at their ends lugs extending over the lenses and including holes or eyelets through which are passed fixing means such as screws or rivets.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and a device for mounting eyeglass lenses. 
     2. Description of the Prior Art 
     In a prior art method of mounting lenses, a plastics material (“nylon” or the like) filament is engaged in a peripheral groove in a lens and is attached at its ends to a frame which extends along the edge of the lens, usually at least along the top edge of the lens, and which has articulated branches at its ends and a central portion forming a bridge between the lenses. 
     This way of mounting lenses has the advantage of being light in weight, attractive in appearance, durable and easy for an optician to carry out. However, the frame portion extending along the top edge of the lenses forms a bar in the field of view of the wearer of the eyeglasses and gives a sensation of limiting their field of view. 
     To remedy this drawback, rimless eyeglasses have been proposed, in which articulated branches and a bridge are fixed directly to the lenses by means of screws, rivets or the like fitted into holes drilled into the lenses in the vicinity of their periphery. Rimless eyeglasses give the wearer a sensation of widened field of view, but it is relatively difficult to fit the branches and the bridge to the lenses. Because of the great diversity of lens, branch and bridge shapes and sizes, the fitter has no template for accurately marking the positions of the drilling points on the lenses. Mounting the lenses is therefore long and costly, because a relatively large number of lenses may be broken during mounting or made unusable by incorrect positioning of the holes relative to each other and to the lenses. What is more, the mounting is loose and unstable if the holes or the notches formed in the lenses are slightly oversized. 
     In one prior art device each articulated branch has a small lug that extends a few millimeters over the lens in a substantially radial direction and terminates in an eyelet or the like through which passes a screw or a rivet. Likewise, each end of the bridge is extended by a similar lug terminating in an eyelet through which a fixing screw or a rivet passes. For the mounting to be stable, an end of each articulated branch and each end of the bridge has another lug a few millimeters long, substantially perpendicular to the first lug and pressed onto the periphery of the lens. 
     To fit this device, one articulated branch and one end of the bridge are offered up to a lens, the position of the eyelets is marked on the lens with a pencil or the like, and the lens is drilled at the marked places. The positions of the eyelets must be marked with great accuracy and the lens must be drilled to the exact diameter of the fixing screws used. Otherwise, the mounting is slack and the branches and the bridge can turn relative to the lenses, which makes the eyeglasses difficult to wear and often requires the optician to start again with new lenses. 
     A particular object of the present invention is to alleviate these drawbacks by providing a method and a device for mounting lenses that are simple, accurate, easy to use, inexpensive, durable, light in weight and attractive in appearance. 
     OBJECT OF THE INVENTION 
     The invention provides a method of mounting eyeglass lenses on a frame comprising two articulated branches and a bridge having at their ends means for fixing them to the lenses and a small lug adapted to extend along the periphery of the lens, in which method, on each lens, said lug at one end of said bridge is connected to said lug on one articulated branch by a plastics material filament engaged in a peripheral groove in said lens, after which said articulated branch and said bridge are fitted to said lens by drilling said lens and fitting fixing means. 
     The method according to the invention combines the advantages of plastics material filaments and rimless eyeglasses but avoids their disadvantages. In particular, the positions of the holes to be drilled in the lenses are marked automatically when the branches and the bridge are fitted to the lenses and secured by the plastics material filament engaged in the peripheral grooves in the lenses. After drilling the holes in the lenses, it is a simple matter, taking only a few moments, to insert fixing members into the eyelets of the branches and the bridge and the holes in the lenses. 
     The invention provides too a device on which eyeglass lenses can be mounted, said device comprising two articulated branches and a bridge whose ends comprise small lugs intended to extend along the periphery of each lens and means for fixing said device to said lenses, in which device, for each lens, said lugs at the ends of an articulated branch and said bridge are connected by a plastics material filament engaged in a peripheral groove in said lens. 
     This device has the advantage of being simple, light in weight, attractive in appearance, inexpensive and usable without special adaptation for all shapes of lenses. 
     In one embodiment of the invention each branch includes said lug adapted to extend along the periphery of a lens to guide or attach the plastics material filament and another lug extending over a face of the lens and including an eyelet adapted to receive lens fixing means. 
     Likewise, the bridge includes at each of its ends said lug adapted to extend along the periphery of a lens to guide or attach the plastics material filament and another lug extending over a face of the lens and including an eyelet adapted to receive lens fixing means. 
     The eyelets are preferably circular or substantially circular. 
     The eyelets are simply holes formed in said other lugs of the branches and the bridge. 
     The fixing members include screws, rivets or the like or spring clips. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantages of the invention will be apparent from the following particular description of several preferred embodiments of the invention as illustrated in the corresponding accompanying drawings in which: 
     FIGS. 1 and 2 are diagrammatic front and plan views, respectively, of the device according to the invention. 
     FIGS. 3 and 4 are partial diagrammatic front views to a larger scale of the essential components of the device. 
     FIGS. 5 and 6 are partial diagrammatic perspective views of a different embodiment of the components. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the embodiment shown in FIGS. 1 and 2, the reference numbers  10  designate eyeglass lenses whose periphery  12  is formed with a continuous annular groove to receive a very fine, and therefore very hard to see, filament  14  of plastics material of the “nylon” or like type, having a diameter of 0.5 mm, for example. The formation of an annular groove in the peripheral edge of a lens is a standard and inexpensive operation and can be carried out easily and automatically by appropriate machines, with which opticians are generally equipped already. According to the invention, the filament  14  on each lens joins an end lug  16  of a bridge  18  to an end lug  20  of a branch  22  of the foldable or articulated type. 
     As can be seen better in FIGS. 3 to  6 , the end lugs  16  of the bridge  18  are substantially perpendicular to the bridge and are slightly curved to follow the convex curved periphery of the lenses  10 . The ends of the filaments  14  are fixed to the end lugs  16  in a conventional way. For example, each lug  16  has at each of its ends two parallel holes  26  in which the filament  14  is inserted and a groove  30  on its face in contact with the periphery of the lens to receive and mask the ends  28  of the filament  14 . 
     Likewise, the lug  20  of each branch  22  extends perpendicularly to the branch, is curved to follow the periphery of a lens  10  and has at each of its ends at least one hole  32  for the filament  14  to pass through, either inside the lug  20 , as shown in FIG. 6, or outside the lug  20 , as shown in FIG. 4, relative to the lenses  10 . 
     The lugs  16  of the bridge  18  and  20  of the articulated branches  22  are typically a few millimeters long. 
     The bridge  18  is extended at each end by a lug  34  which extends a short radial distance (for example less than 10 mm) over one face of the corresponding lens  10 , preferably the exterior face of the lens. The lug  34  has a hole  36  through which passes a member for fixing it to the lens  10 , for example a screw, a rivet or the like, or a spring clip, as described in more detail below. 
     Each eyeglass branch  22  also includes a lug  38  which extends radially over one face of the corresponding lens  10 , preferably the exterior face of the lens, and which is short, typically less than 10 mm long, like the lug  34  of the bridge  18 . The lug  38  of the branch  22  includes a hole  40  through which passes a fixing member of the type previously cited. 
     In the embodiment shown, the lugs  34  of the bridge  18  and  38  of the branches  22  are substantially aligned with each other. Of course, they could be oriented differently and extend more or less radially relative to the lenses, from their periphery. 
     Lenses are mounted in the following manner: 
     The branches  22  and the bridge  18  are mounted on the lenses  10  by means of the filaments  14  in the conventional way, each filament  14  being for example attached to one end of a branch  16  of the bridge  18 , passed through the holes  32  in the lug  20  of the articulated branch  22 , and then fitted into the peripheral groove of the corresponding lens  10 , fed along to the vicinity of the other end of the lug  16  of the bridge  18 , cut to length and attached at its free end to the lug  16 . To this end, in a manner that is well known in the art, the end of the filament can be heated to melt it and form a ball of plastics material larger than the diameter of the hole  26  in the lug  16  through which the filament  14  passes. The free end of the filament  14  is attached to the lug  16  with the filament  14  disengaged from the peripheral groove in the lens  10 , of course. The combination of the bridge  18 , the branch  22  and the filament  14  is then refitted to the lens  10  by exploiting the elasticity of the filament  14 . Passing the filament  14  through two adjoining holes  26 ,  32  in a lug  16  or  20  is generally sufficient for properly attaching the filament  14  to the lugs, especially if they are made of metal. 
     When the branches  22  and the bridge  18  are in the required positions on the lenses  10 , the positions of the holes  36  and  40  are marked on the lenses and the lenses are drilled at the marked locations. The lenses can advantageously be drilled using the holes  36 ,  38  as drilling guides. 
     In the embodiment shown in FIG. 2, the members  42  for fixing the branches  22  and the bridge  18  to the lenses  10  are of the nut and bolt type. Fixing members in the form of rivets or spring clips, formed for example of bent pins made of spring wire or the like, can equally well be used. Fixing by means of spring clips can be consolidated by depositing a spot of glue into each hole in the lens. 
     As shown in FIG. 1, the positions of the branches  22  and the ends of the bridge  18  on the lenses  10  can be approximately diametrically opposed. Depending on the shape of the lenses, it is also possible to move the branches  22  and the bridge  18  closer to the tops of the lenses. 
     An important advantage of the device according to the invention is that the positions of the branches and the bridge on the lenses are defined positively by the plastics material filament  14  that is tensioned in the peripheral groove on each lens. The tension in the filament  14  means that there is no slack in the mounting, even if the screws fixing the branches and the bridge to the lenses loosen slightly, and the lugs  16 ,  20  prevent the bridge and the branches rotating on the lenses. 
     What is more, the device according to the invention offers all the advantages of lightness in weight and attractiveness in appearance of prior art rimless eyeglasses whilst having the benefit of significantly improved solidity and stability.