Abstract:
The invention relates to a rimless spectacles for use with auxiliary lenses by which magnets are used to attract and hold the auxiliary lenses in place.

Description:
BACKGROUND OF INVENTION  
         [0001]    The invention relates generally to magnetic rimless spectacles wherein auxiliary lenses are fixedly held in place by magnetic attraction between an embedded magnet in an auxiliary lens and a juxtaposed magnetic head of a screw in the primary frame.  
           [0002]    There are many situations where it would be advantageous to be able to quickly change from one type of eyeglass lens to another, among which may be mentioned would be a change from clear lenses to colored, or a change from lenses for correcting for myopia to lenses for reading. Typically, this has necessitated two or more pairs of eyeglasses or spectacles to be carried, resulting in a bulky and unsightly appearance because of the fact that each pair of eyeglasses not only has a lens and frame parts, but also the folding temples.  
           [0003]    One improvement over the early Prior Art solution of separate pairs of glasses was the incorporation of first and second magnetic members which are attached to both the primary and auxiliary frames. This resulted in the user only being required to carry an auxiliary frame. However, the presence of magnets on the front surface of the primary frame were also undesirable, particularly when not being used in conjunction with an auxiliary frame.  
           [0004]    This led to still further improvements in the Prior Art which positioned the magnets behind the primary frame as well as on the inside of the legs, as well as leading to magnet orientations which were both vertical and horizontal. However, what has been missing from the Prior Art is the ability to use magnetic attachment on rimless frames.  
         SUMMARY OF INVENTION  
         [0005]    The invention is directed to the use of magnetic attachments of auxiliary lenses to primary lenses in a rimless spectacle frame.  
           [0006]    In one principal aspect of the present invention, the attachment will utilize magnets which are embedded in the auxiliary lenses to separately attach to magnetic or magnetizable screw heads which are used to connect both the nose bridge and legs of the spectacle to the primary lenses.  
           [0007]    In another principal aspect of the present invention, the invention enables a user to attach auxiliary lenses which are connected by a bridge piece to a rimless frame by magnetic attachment.  
           [0008]    Accordingly, it is an object of the present invention to provide a wearer of rimless spectacles with magnetically attached auxiliary lenses, each lens being separately attached.  
           [0009]    It is another object of the present invention to provide a wearer of rimless spectacles with magnetically attached auxiliary lenses, the auxiliary lenses being connected by a bridge piece.  
           [0010]    These and other objects of the present invention will become more readily apparent from a reading of the following detailed description taken in conjunction with the accompanying drawings wherein like reference numerals indicate the parts and appended claims. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]    The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein:  
         [0012]    [0012]FIG. 1 is a perspective view of a primary frame and detached auxiliary lenses, the auxiliary lenses shown with insertable magnets and magnet holders;  
         [0013]    [0013]FIG. 2 is a perspective view similar to FIG. 1 with a bridge between the two auxiliary lenses;  
         [0014]    [0014]FIG. 3 is top elevational view of FIG. 1 when the auxiliary lenses are attached to the primary frame;  
         [0015]    [0015]FIG. 4 is an enlarged assembly view showing one side screw attachment, the screw shaft and front extension shown in cross-section; and  
         [0016]    [0016]FIG. 5 is an enlarged view of a cylindrical sleeve or bushing for use in the primary lens. 
     
    
     DETAILED DESCRIPTION  
       [0017]    Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting the same, the Figures show a magnetic attachment means for a rimless spectacle frame.  
         [0018]    As illustrated in FIG. 1, the rimless primary frame has a pair of primary lenses  32  connected by a bridge  20  and adapted for wearing through engagement of a pair of bendable rearwardly extending legs  12 . The legs may be pivotally inwardly collapsable for easy storage by axial rotation about pivot hinge  16  which is fixedly connected to leg extension piece  18  for fastening engagement with one of the primary lenses  32 . For the comfort of the user, a pair of pliable plastic inserts  14  are often optionally inserted over legs  12 . Each leg extension piece  18  is typically fastened to one primary lens  32  by insertion of a screw through aperture  44  in the primary lens as well as aperture  48  in leg extension piece  18 . Screw shaft  22  has a head  42  which is greater in diameter than a diameter of aperture  44  to enable secure fastening engagement of primary lens  32  with leg extension piece  18  by rotational longitudinal axial movement of nut  34  on the threaded end of screw  22 . While a screw is envisioned to embody the preferred embodiment of the invention, it is also envisioned that the fastening means could also be a non-threaded shaft with a head onto which a frictional gripper could be inserted by longitudinal axial movement thereby frictionally securing primary lens  32  and extension piece  18  together. Optionally, cylindrical sleeve or bushing  36 , with laterally and peripherally extending ledge  40 , better illustrated in FIG. 5, is positioned within apertured opening  44  of primary lens  32  prior to fastening.  
         [0019]    Primary lenses  32  are held in a spaced apart relationship by bridge piece  20  which is secured to the lenses in a manner similar to that described for leg extension pieces  18 , i.e., preferably by threaded engagement of nuts  34  with threaded screw shafts  22 , optionally within cylindrical sleeves  36  within apertured openings  44  of the two primary lenses  32 . Bridge piece  20  will typically additionally have nose pads  52  fixedly attached for resting on a user&#39;s nose.  
         [0020]    At least head  42  of the fastening screw will be magnetic or magnetizable or must be capable of having a sufficient amount of iron such that magnetic interaction with a magnet will result in an attractive force. In one preferred embodiment, the screw is an iron-chromium carbon metal composite. In a preferred embodiment, the composition of this screw will be approximately 60% chromium, 1% carbon, 2.5% silver, 0.06% phosphorus, 0.05% sulfur with a balance of iron. The key is that at least the head of the screw must be capable of interacting with a magnet and contain a sufficient amount of magnetic material so that an auxiliary lens  30  may be held in close proximity to the primary lens  32  by essentially magnetic attractive forces alone, even when subjected to forces normal to the axis of magnetic attraction, such as gravity or other downward forces having a vector normal to that of the axis of magnetic attraction as created by walking, jogging or running. The composition of the screw or other fastening device is predicated by the magnetic requirements, but also by aesthetic concerns, such as the ability to be color plated to match the frame colors. It is within the skill of those in the art to modify the composition of the fastening attachment to achieve these goals, as well as hardness considerations inherent in normal fabrication of fastening devices which often have slots in the head of the screw to facilitate rotational movement of the screw fastening shaft. It should be noted that physical contact between magnet  24  and screw head  42  is not essential, although preferred, if the strength of the magnet is sufficiently strong.  
         [0021]    Auxiliary lenses  30  are attached to primary lenses  32  by magnetic attraction of a pair of magnets  24  which are embedded into each auxiliary frame  30  in apertures  28 . Optionally, magnets  24  are positioned within magnet holders or sleeves  26 , optionally having laterally and peripherally extending ledges  46 , prior to insertion into apertures  28 . It is evident that apertures  28  in the auxiliary lenses must be in fairly close mating alignment with juxtaposed apertures  44  in the frames in order to maximize the magnetic attractive forces which retain the auxiliary lenses in physical proximity with the primary lenses. While a total of four mating attractive magnet and screw head locations are shown in FIGS. 1 and 3, there is no need to limit the invention to this number and higher numbers of magnetic pairs are envisioned. For example, for users where aggressive downward normal forces to the axis of magnetic attraction are expected to be incurred, i.e., running or jogging, additional mating magnetic attractive combinations are within the scope of the invention. In this alternative embodiment, it is envisioned that additional apertures would be positioned in both the auxiliary and primary lenses, but in these instances, additional magnets  24  with optional magnet holders or sleeve  26  would be positioned in both the primary and auxiliary lenses.  
         [0022]    The invention additionally is not limited to magnetic attraction of separate auxiliary lenses to primary lenses. It is within the scope of the invention to have a bridge piece positioned between the two separate auxiliary lenses shown in FIG. 2. In this alternative embodiment, it is believed that only one magnetic pair combination is required on each lens and that attraction would be supplemented by a magnetic attraction between the two bridges between the primary lenses and auxiliary lenses respectively, although FIG. 2 illustrates a more preferred embodiment, wherein four pairs of magnetic attractions are utilized. In this embodiment, it should be understood that bridge  20  between auxiliary lenses  30 , may be of a geometry which is essentially identical as shown for that between the primary lenses, or it may be different. The bridge may be attached to the back of the auxiliary lenses or may be attached to the front. It should be recognized that when a bridge is positioned between the auxiliary lenses as illustrated in FIG. 2, the clip or nut  38  which secures the head of the auxiliary screw  50  to the auxiliary lens must be relatively flat, and the shaft associated with the auxiliary screw head is typically shorter than that typically used to fasten the primary lens to either the nose bridge  20  or leg extension piece  18  so as to be able to engage with the screw head  42  securing the primary frame bridge to the primary lenses.  
         [0023]    In one specific embodiment, the magnet used in the invention is a unipolar magnet with a gauss rating of 10,000. The magnetic property has a Hc rating equal to or greater than 4.93. It is recognized that these values are presented for illustration of the best mode only, and the invention is not limited to the same, and both higher and lower magnetic values are capable of being used in the instant invention. It is recognized by those of ordinary skill in the art that as the surface area increases between the attractive regions, it may be possible to use magnets which are less strong, while if magnet size minimization is the goal, then more powerful magnets are required. It is also understood that unipolar magnets are not absolutely essential for this invention, particularly when more than four attachment pairs are envisioned, when polar magnets are believed to be useful in the additional locations.  
         [0024]    While it is envisioned that metallic rimless frames are the best mode of practicing the invention as this time, it is envisioned that legs  12  and bridge piece  20  could be made of plastic. In this particular specialized embodiment, it is anticipated that optional magnets may be positioned within bridge piece  2 O as well as optionally into a bridge piece which connects auxiliary lenses  30  in this specialized embodiment.  
         [0025]    This invention has been described in detail with reference to specific embodiments thereof, including the respective best modes for carrying out each embodiment. It shall be understood that these illustrations are by way of example and not by way of limitation.