BACKGROUND OF THE INVENTION I. Field of the Invention The present invention pertains to an eye glass assembly and more particularly to an improved means for mounting an eye glass lens within the rim portion of an eye glass frame.

II. Description of the Prior Art

Throughout the long history of eye glasses, numerous techniques have been employed to mount an eye glass lens within the rim portion of the eye glass frame. As noted in U.S. Pat. 3,904,282 to Batista dated September 9, 1975, conventional lenses were provided with beveled edges formed around the periphery of the lens. The beveled lenses were convex in configuration and were received within mating concave grooves formed in the inner peripheral edge of the rim portion of the eye glass frame. The concave grooves and convex edges were provided with a sharp apex such that each were essentially V-shaped. Conventionally, the V-shaped bevel is approximately one millimeter in depth and has a base of one millimeter.

A common concern in the design and manufacture of eye glasses is the protection of the person wearing the eye glass. Injury can occur by reason of the eye glass lens breaking or by reason of the eye glass lens becoming dislodged from the rim portion. To prevent the eye glass lens from becoming dislodged and being impacted against the eye of the wearer, so called safety glasses were developed. The frame of the safety glass includes a rim portion which is thicker on the back side of the rim than on the front. As a result, the leg of the V-shaped groove on the side of the groove facing the rim back side is longer than its opposing leg. With this configuration, there is increased

surface area opposing movement of the lens out of the back of the rim portion.

Conventional eye glasses included lenses formed from tempered glass or a plastic known in the industry as CR-39. When using lenses formed from such material in con¬ ventional eye glass f ames, prior art V-shaped grooves and safety glasses were adequate since the strength of the lens material was less than the strength of the bond between the lens and the rim. As a consequence, upon impact by a given force, the lens would fracture even though the force would not be sufficient to dislodge the lens.

The art of eye .glass manufacture- and design has evolved with new materials being used for the manufacture of eye glass lenses. A new material now on the market is polycarbonate which has a higher strength than conventional tempered glass or CR-39. An impact of sufficient force to fracture tempered glass or CR-39 plastic lenses would not fracture a polycarbonate lens. Indeed, forces insufficient to fracture a polycarbonate lens could be sufficient to dislodge the lens from a prior art rim. If this were.to occur during use, the individual wearing the eye glass could be seriously injured by the dislodged lens. •

As a result of the evolution of lens material, the strength of the lens material is no longer the limiting factor in the safety of the eye glass. Now, the safety is limited by the bond between the lens and the rim. It would be desirable to provide an improved bond between the lens and the rim to take full advantage of the superior strength of lenses formed from polycarbonate. Such an arrangement would enhance the overall safety of eye glasses and benefit the general public wearing military eye wear, prescription or piano industrial eye wear, sports eye wear and sun glasses. However, the art has yet to find such an arrange¬ ment.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to pro¬ vide an eye glass assembly having improved bonding between the frame rim and an eye glass lens. A further object of the present invention is to provide a method for retrofitting existing eye glass frames to incorporate an improved bonding method.

According to a preferred embodiment of the present invention an eye glass assembly is provided comprising an eye glass frame having a rim portion with an inner peripheral .edge which defines a lens receiving opening. A groove is formed in the inner peripheral edge surrounding the opening. The groove defining surfaces include an annu¬ lar rear retaining surface adjacent the back side of the rim portion. The annular rear retaining surface is generally parallel to a dimension extending between opposing surfaces of the inner peripheral edge. An eye glass lens of the present invention has an outer peripheral edge sized to be received within the lens receiving opening. A retaining ridge is disposed on the outer peripheral edge and protrudes into the groove formed in the rim. The retaining ridge has a first annular retaining surface opposing the rear retaining surface and parallel thereto. The eye glass assembly of the present invention has an improved bond between the eye glass lens and the eye glass frame. The improved bond requires greater force to dislodge the lens from the frame on impact. Also, the pre¬ sent invention provides for surprising benefits in that the method of manufacture enhances quality control since wear of the lens grinding machinery will be more readily detected during assembly of the eye glass.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an eye glass assembly according to the present invention;

Fig. 2 is a view taken along line II-II of Fig. 1; Fig. 3 is a sectional view similar to Fig. 2 showing an eye glass of the prior art;

Fig. 4 is a view similar to that of Fig. 3 showing an alternative eye glass of the prior art;

Figs. 5 and 6 are sectional view of alternative embodiments of the present invention;

Fig. 7 is a top plan view of an eye glass assembly according to the present invention;

Figs. 8-10 are views of eye glass lenses according to the present invention; Fig. 11 is a sectional view of an eye glass assembly of the prior art;

Fig. 12 is a view similar to that of Fig. 11 of the eye glass assembly of the present invention; and

Figs. 13 and 14 are views of the eye glass of the prior art and the present invention, respectively, showing, in vector format, the response of the eye glass to impact.

DESCRIPTION OF THE PREFERRED EMBODIMENT Figs. 3 and 4 show prior art means for mounting eye glass lenses within the rim portions of an eye glass frame. Fig. 3 shows the mounting for a normal eye glass and Fig. 4 shows the mounting for a safety glass. As shown in Fig. 3, the rim portion 50 has a cylindrical inner sur¬ face 51. A V-shaped groove 52 is formed within inner sur- face 51 and extends completely about the rim. A lens 53 has its peripheral edge 54 ground such that the peripheral edge 54 is generally cylindrical and includes a V-shaped convex ridge 55 which conforms with the size and shape of concave groove 52. In the embodiment of Fig. 4, the safety glass is

shown as having a rim 60 having a V-shaped concave groove 62 formed in its inner peripheral surface 61. The safety glass rim 60 is formed such that the thickness of the rim on the side 60a facing the user is thicker than on the side 60b facing away from the user. The lens 63 has a convex

V-shaped bevel 65 sized to conform with groove 62. As men¬ tioned in the previous description of the prior art, the increased thickness portion 60a is provided to prevent the lens 63 from being popped out of the rim 60 and impacted against the user by reason of a force applied to the lens urging it toward the user.

While the above prior art mounting arrangements were adequate in that they took advantage of the strength of the material of the prior art lenses, such mountirfg techniques are not fully satisfactory with improved strength lens materials. For example, with polycarbonate material lenses, the strength of the lens material is such that it will not break in response to impacts sufficient to force the lens out of the prior art mounts. The V-shaped grooves of the prior art provide a natural pathway for guiding a lens out of the mount. This is demonstrated, in Fig. 13 where arrows 56, 57 and 58 represent directional forces applied to a lens 59 within a rim 67. The dotted arrows 56a, 57a and 58a show the response of the lens 59 to the various impacts. It can be seen that the V-shaped groove and corresponding V-shaped bevel assist the prior art lens 59 in being dislodged from the prior art rims 67.

Referring now to Fig. 1, the present invention will now be described. An eye glass assembly is generally shown at 10. The assembly 10 comprises a frame 12 which includes two rim portions 14 and 14a. The rim portions 14, 14a are joined by a bridge 16. Extending from opposite portions of the rims 14, 14a are a pair of bows 18 and -18a to be hung on ears of a user. The rims 14, 14a surround eye glass lenses 20 and 20a.

Lenses 20 and 20a are formed of transparent rigid and durable material, preferably polycarbonate. Lenses 20, 20a are mounted within rim portions 14, 14a in similar man¬ ners and the description of the mounting of lens 20 will suffice as the description of the mounting of lens 20a.

As is conventional, frame 12 is formed from a flat sheet of frame material such as plastic. The opening within the rim portions 14, 14a is cut out and a groove is formed in the inner peripheral edge of the rim. With the groove formed, the frame 12 is formed to provide a slight arc for each of the rim portions 14, 14a, as can be seen in the view of Fig. 7.

In the present invention, the rim 14 has a generally cylindrical inner peripheral edge 22 as shown in Fig. 2. For purposes of this description, cylindrical is not intended to mean circular in cross section, but instead means that opposing surfaces are parallel. The opposing surfaces of edge 22 defines a lens receiving opening 24. The rim portion 14 is provided with a continuous groove 26 formed along the inner peripheral edge 22. The groove is defined by surfaces of the rim portion 14 with the groove defining surfaces including an annular rear retaining surface 26a and an opposing axially aligned spaced apart forward retaining surface 26b. Surface 26a and 26b are formed generally perpendicular to edge 22. When the frame blank is formed to provide the curvature to the rim portions 14, 14a as shown in Fig. 7, it will be appreciated that sur¬ faces 26a and 26b will not be planar surfaces but will reside in a surface having a radius equal to the radius of curvature of the rim portion. When so formed, these annu¬ lar surfaces 26a and 26b will, be generally parallel to the direction of a dimension extending between the opposing /• surfaces of the inner peripheral edge 22. i

With the ridge portion 14 so formed to include groove 26 lying in a non-planar surface, an eye glass lens

20 according to the present invention may be formed. The lens blank is mounted in conventional equipment for rota¬ tion about its axis. A grinding tool dimensioned to grind out a ridge as will be described is mounted for rotation about a parallel axis and movable about the periphery of the lens blank in a path for its grinding element to follow the contour of the inner peripheral edge 22 of rim portion 14 and also movable within the non-planar surface of groove 26. The lens 20 is formed by grinding the peripheral edge of the lens blank such that the. finished lens 20 has an outer peripheral edge 30 which conforms in shape to . inner peripheral edge 22 in abutting relation. A continuous integrally form and rigid retaining ridge 32 is disposed on the outer peripheral edge of the lens 28 and protrudes theref om.

The retaining edge 32 is sized to be received within groove 26 and is provided with a first annular retaining surface 32a which is parallel and abutting annu- lar rear retaining surface 26a. Similarly, edge 32 is pro¬ vided with a second annular retaining surface 32b which is parallel and abutting rear retaining surface 26b.

With the lens 20 formed as described above, rim 14 of frame 12 (which is preferably made of metal or plastic which will expand and soften when heated) is heated and lens 20 is inserted within opening 24 with retaining ridge 32 received within groove 26. So mounted, the eye glass assembly 10 has remarkably improved bonding between lens 20 and rim portion 14. This is attributable to the fact that the surface 32a and abutting surface 26a are parallel to the dimension. extending between the opposing surfaces of edge 22. As a consequence of this alignment, impact on the front surface of such a lens (for example, lens 59' in rim 67' shown in Fig. 14 with the impact indicated by arrows 56', 57' and 58') results in the directional response of the lens being indicated by the broken arrows 56a', 57a ¹

and 58a ¹ . It can be seen the mounting of the present invention creates a moment about the ridge 32 at the point of interface between outer peripheral edge 30 and inner peripheral edge 22. As a result, the lens is not directed out of the rim 14 upon impact. The limiting factor in the safety of the glass is no longer the strength of the mount but is instead the superior strength of the polycarbonate lens material.

Referring to Figs. 8 through 10, a lens of the present invention is shown in three examples. The lens of Fig. 8 is a piano lens 70 having its convex surface 70a provided with a radius of curvature equal to that of its concave surface 70b. Such lenses are commonly used in recreational eye wear or industrial eye wear for people having normal vision. The piano lens of the present inven¬ tion has a generally cylindrical outer peripheral edge 71 meaning that opposing surfaces of the edge 71 are parallel (not necessarily circular in cross section). The ridge 72 extends generally perpendicular to the edge 71 and lies in the surface of curvature of a groove formed in the rim por¬ tion of a frame for which lens 70 is intended. Fig. 9 shows a minus power lens 80 for use in eye wear for near sighted individuals. The convex surface 80a has a longer radius of curvature than that of concave surface 80b. Fig. 10 shows a plus power lens 90 for far sighted individuals where the convex surface 90a has a shorter radius of cur¬ vature than the concave surface 90b. Each of the lenses in Figs. 8 through 10 has a retaining ridge according to the present invention lying in the surface of curvature of its intended groove in an eye glass frame. In the plus power lens 90, the outer peripheral edge of the lens narrows down to about one millimeter which is fairly standard. As a result, this provides a practical limitation on the spacing between surface 32a and 32b of lens ridge 32. Fig. 5 shows an alternative embodiment of the pre-

sent invention where the rim portion 14' has an inner peripheral ridge 22' in which is disposed a groove 26' of the present invention. The thickness of the rim portion 14' on the side of groove 26' which includes surface 26a' has an increased thickness represented by the letter D. As a result, for opposing surfaces of the peripheral edge 22' on a side of groove 26' adjacent the eye glass wearer, the distance between the opposing surfaces is smaller than the distance between opposing surfaces on the side of groove 26' away from the wearer. This provides additional shoulder space on surface 26a' which further inhibits dislodgement of the lens and provides a greater moment at the rim 14' to redirect an impact.

The present invention is also adaptable to prior art eye glass frames having V-shaped grooves along the inner peripheral edge of the frame rim portions. As shown in Fig. 6, the prior art V-shaped grooves are conven¬ tionally one millimeter in depth from the base of the groove to the apex (indicated by dimension Oχ ) . By dimen- sioning the ridge of the present invention to have rear and forward retaining surfaces of one millimeter each, excess material within the rim portion can be removed to provide a mating groove. Fig. 6 shows a particular embodiment of the present invention specifically suited for adapting prior art eye glass frames to the teachings of the present inven¬ tion. In the embodiment of Fig. 6, the rim 14' ' was origi¬ nally provided with a V-shaped groove 62' ' disposed in the inner peripheral edge 61 ' ' . In the modification, a second groove 26'' is formed within the first groove 62''. The second groove 26'' is formed by cutting away the waste material 14a' ¹ and 14b ¹ ' between the desired location of a rear annular retaining wall 26a'' and a forward annular retaining wall 26b ¹ ' both within the teachings of the pre¬ sent invention.

It has been shown how the teachings of the present invention provide for an eye glass assembly with advantages over the prior art. Namely, by using the present inven¬ tion, the full benefit attainable with improved lens material such as polycarbonate can be attained. In addi¬ tion, the present invention provides for an additional surprising benefit which improves quality control in pro¬ duction of eye glasses and further insures safety for the eye glass wearing public. With reference to Fig. 11, it can be seen that in the prior art eye glass mounting arrangement, the quality of the bond between the lens 53' and the rim 50' requires that the V-shaped ridge 55' be shaped as closely as possible to conform with the V-shaped groove 52'. However, the outer peripheral edges 54' and V-shaped ridge 55' are typically formed by grinding elements having a profile corresponding to the profile of the desired ridge 55' and edge 54'. Throughout the usage of the grinding tool, the tool wears with use. Typically, the first portion of the tool to show substantial wear is the portion which defines and shapes the V-shaped ridge. Specifically, as the tool is used, the V-shaped ridge 55' tends to lower its apex and spread out the opposing legs which define the V-shape. As this happens, lenses made on the cutting tool become increasingly out of alignment (as shown in Fig. 11) and become increasingly likely to pop out of the rim portion 50'. Eventually, the wear on the tool becomes so great that an operator will notice the improper fit. However, by this time a substantial number of inferior products may find their way into the marketplace and present a potential substantial risk of serious injury to the eye glass wearing public.

A surprising benefit of the present invention can be seen with reference to Fig. 12. Fig. 12 shows a rim portion 14''' having a groove 26' '' according to the pre-

sent invention formed along its inner peripheral edge 22' ¹ '. A lens member 20 ' ' ' is provided having its ridge 32''' made according to the present invention. The ridge 32" ^• ' will be formed on grinding elements having profiles identical to that of the desired profile of ridge 32''' and outer peripheral edge 30'''. As the grinding element wears through use, the distance between opposing retaining walls 32a' ¹ ' and 32b ¹¹ ' will increase. As a result, the ridge 32' ' ' will no longer fit into the groove 26 ' ' ' as the grinding tool wears. Therefore, the lens production method of the present invention is self correcting. As opposed to the prior art, when the lens grinding element of the pre¬ sent invention wears, the operator will quickly notice this since it will become impossible to fit the lens 20''' into the rim portion 14'' '. Being promptly alerted to the wear of the grinding tool, the operator can take necessary steps to repair or replace it thereby insuring that only properly mated lenses 20 ' ' ' and rims 14 ' ' ' will find their way to the consumer. As can be seen from the foregoing, the objects of the present invention have been attained in a preferred manner. Modifications and equivalents of the disclosed contents such as readily occur to those skilled in the art are intended to be included in the scope of this invention. Thus, the scope of this invention is intended to be limited only by the scope of the claims such as are, or may here¬ after be, appended hereto.