Manually Variable Light Filtering Sunglasses

The accompanying drawings, which are incorporated and constitute a part of this specification, illustrate preferred embodiments of the invention and, together with the general description given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.

FIG. 1 is a rear elevation of a pair of eyeglasses in accordance with the principles of the present invention, the right rear lens being completely mounted within the right rim portion of the eyeglass frame and the left rear lens being in the "insertion stage" of mounting to the left rim portion of the frame;

FIG. 2 is an enlarged partial view of the left rear lens and the left rim as shown in FIG. 1 and showing a first embodiment of a rotating lens according to the principles of the present invention;

FIG. 3 is an enlarged partial view similar to FIG. 2 of a second embodiment of a rotating lens according to the principles of the present invention;

FIG. 4 is an enlarged cross sectional view taken on lines 4--4 of FIG. 1;

FIG. 5 is an enlarged cross sectional view taken on lines 5--5 of FIG. 1;

FIG. 6 is an enlarged cross sectional view taken on lines 6--6 of FIG. 1; and

FIG. 7 is an enlarged side view of a rotating lens for a left rim portion.

With reference to FIG. 1 there is illustrated a pair of variable density sunglasses 5. Glasses 5 are illustrated with an exemplary eyeglass frame 10 for purposes of explaining the principles of the present invention. Although the invention is not so limited, frame 10 is preferably a plastic molded body including a left rim portion 12 and a right rim portion 14 coupled together by a bridge structure 16 on which is also defined a nose piece support structure 18. To hold frame 10 to the wearer's face (not shown), folding side bows 20 are hingedly coupled to rim portions 12 and 14 by side bow hinges 22 as is conventional.

As is typical, each rim portion 12 and 14 surrounds a lens-receiving hole 24 generally in a plane parallel the front and back of frame 10 as defined between forward 26 and rearward facing 28 exterior sidewalls, respectively. Preferably, each rim portion 12, 14 has at least one interior groove 30 formed therein between sidewalls 26, 28 and surrounding lens-receiving hole 24. Each groove 30 is preferably circular and communicates with exterior sidewall 28 via an access channel 32 to define a thread plane for purposes of threadably receiving a rotatable lens 34, the particulars of which will be explained by reference to FIG. 7.

As seen in FIG. 7, lens 34 preferably has a circular periphery 36 to engagingly mate with circular groove 30. To permit threading engagement with groove 30 via access channel 32, lens 34 is provided with a cut 38 extending radially inwardly from periphery 36 to define thread edges 40, 42 on either side of cut 38. As shown in FIG. 7, thread edges 40 and 42 are preferably permanently flared in opposite axial directions for purposes to be described hereafter. For purpose of left rim portion 12, and as seen in FIG. 7, thread edge 40 and the adjacent area of lens 34 is flared outwardly towards the front of lens 34 while thread edge 42 and the adjacent area of lens 34 is flared inwardly beyond the back of lens 34. Thread edges 40, 42 are flared in the reverse fashion (not shown) for purposes of right rim portion 14.

Preferably the internal end 44 of each cut 38 communicates with a rounded, stress relieving aperture 46 formed through lens 34. Rounded aperture 46 distributes fatiguing or internal stress that results from flaring of edges 40, 42 and their compression in use as will be described. Each flex cut 38 (at the time of "cutting in" to the lens during manufacture and before the lens edges are permanently flared) is preferably about 0.010 inches in width and about 0.250 inches in height, the top 0.075 inches of which comprises the round opening 46.

Mounting of lens 34 will be described with reference to mounting lens 34 as shown in FIG. 7 to left rim portion 12. To this end, edge 40 of lens 34 is inserted into access channel 32 and lens 34 rotated clockwise. As lens 34 rotates, more of periphery 36 of lens 34 becomes engaged within groove 30 (see FIGS. 4 and 5, for example) until edge 42 passes through channel 32 and into groove 30 whereupon the entire periphery 36 of lens 34 will become completely received within groove 30. A lens 34 is shown so-received in right rim portion 14 in FIG. 6. To remove or demount lens 34, it is merely rotated in a reverse or opposite direction from the mounting direction so that edge 42 first passes out through access channel 32.

Lenses 34 are preferably convex discs of pliable plastic. During manufacture, edges 40, 42 of lens 34 are permanently flared adjacent to the flex cut 38, as shown in FIG. 7. Because of the pliability and resiliency of the lens, these permanently flared edges aid the wearer in the removal and remounting of the lens by naturally leading the lens in and out of groove 30 via access channel 32. Edges 40, 42 are preferably flared further apart than the width of groove 30 between its walls 48 so that when periphery 36 is entirely within groove 30, edges 40, 42 will be squeezed together thereby. That is, once lens 34 is completely mounted within its groove 30, permanently flared edges 40, 42 will produce a pressure against groove walls 48 as a result of being constricted thereby. The coaction of edges 40, 42 and walls 48 provides frictional engagement between the lens and the groove walls to assist in holding the lens in any desired set position and prevent unwanted rotational movement of the lens 34 with respect to frame 10.

With the foregoing arrangement, a rotatable lens may be readily mounted and demounted to an eyeglass frame. Further, and in connection with providing variable density sunglasses in accordance with the invention, each rim portion of the eyeglass frame 10 is further provided with a second groove 50 outboard of and generally parallel groove 30. Preferably, fixedly secured within outer groove 50 is a polarized eyeglass lens 52. As is typical for sunglasses, each of lenses 52 is preferably lightly tinted and mounted in a non-rotatable fashion with respect to the frame 10. Also, forward lenses 52 are preferably convex discs of pliable plastic, rigid plastic, or optical glass as is conventional. In mounting lenses 52, it is preferable to position the lenses such that the light polarizing direction or angle of each lens 52 is parallel to the other and that the polarized, transmitted light of these lenses is linear and horizontal with respect to the normal worn position of the frame 10.

To function as variable light filtering or variable density sunglasses, lenses 34 are also preferably polarized. Hence, once lenses 34 are in groove 30, lenses 34 may be rotated or adjusted to vary the total light intensity transmitted through each aligned pair of lenses 34, 52. Preferably, grooves 50, 30 are spaced approximately 0.03 inches apart to define an air gap or space 54 between each lens pair 34, 52. Air space 54 constitutes a buffer zone between the lenses of each pair of front and rear lenses 52, 34 that prevents frictional scratching between the surfaces of the lenses during adjustment. Further, grooves 50, 30 are preferably completely circumscribed by the plastic of their associated rim portion 12 or 14 to thus surround the periphery of both lenses 34, 52 associated with that rim portion. In this manner, the air gap 54 is substantially enclosed so as to reduce the likelihood of foreign material getting into gap 54 when the glasses 5 are in use.

As stated earlier, removal of lens 34 is accomplished simply by rotating lens 34 in a direction opposite its mounting direction, causing edge 42 to pass into access channel 32 and eventually the entire periphery 36 of lens 34 to unthreadably pass through access channel 32. Where necessary, this simple, threadable mounting and demounting of the rear lenses 34 facilitates the cleaning of the inside surfaces of each pair of aligned lenses 34, 52. This simple process also permits easy replacement of a rotatable lens 34 should such be necessary.

When used as variable light transmitting sunglasses, rotational adjustment of lenses 34 may be accomplished by use of adjustment tabs 60 mounted to lens 34 by a rivet, glue or other fastening means (not shown). Preferably, adjustment tabs 60 are mounted to an exterior surface of lens 34 facing the wearer (not shown). According to the embodiment shown in FIG. 3, adjustment tab 60 is preferably located over aperture 46 so as to occlude light which might otherwise pass through lens 34 at aperture 46. Alternately, tabs 60 may be positioned away from the cut 38 and aperture 46 as shown in FIGS. 1 and 2. As shown in FIGS. 5 and 6, adjustment tabs 60 are preferably bevelled on a bottom side as at 62 to facilitate removal of lens 34 from frame 10 by providing a gripping surface by which to grab the lenses. Preferably, rearwardly directed surfaces 64 of adjustment tabs 60 are spherical in shape, in order to reduce the likelihood of injury to the wearer's eyes (not shown) in the event that the sunglasses 10 are accidentally compressed against the wearer's face.

In a preferred embodiment, flex cuts 38 are positioned in lenses 34 such that when cuts 38 are located at a bottommost position, at six o'clock with respect to the frame 10 (as seen in FIG. 1), the polarizing directions or angles of all of the front and rear lenses 34, 52 are parallel to each other, and in a linear and horizontal light polarizing position.

With this positioning of the lenses and the flex cuts with respect to the frame, the following will occur: As left rear lens 34 is rotated clockwise ninety degrees and right rear lens 34 is rotated counterclockwise ninety degrees (by applying appropriate finger pressure to adjustment tabs 60) such that the adjustment tabs progress toward their 9:00 and 3:00 positions, respectively, the left ocular unit (composed of rim portion 12 and its associated pair of lenses 34, 52) and the right ocular unit (composed of rim portion 14 and its associated pair of lenses 34, 52) will vary between transmitting the maximum amount of polarized light and transmitting a minimum amount or no light to the wearer-viewer (not shown). By rotating rear lenses 34 to the desired position, the ocular units of the sunglasses may be adjusted to filter out any desired percentage of light. This adjustment may be easily performed while the sunglasses are worn and may be varied for one ocular unit independent of the adjustment for the other ocular unit.

Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is, therefore, not limited to the embodiments and illustrated examples shown and described. Accordingly, departures may be made from such details and/or without departing from the spirit or scope of the present invention .