Universal center bridge mounting mechanism for clip-on sunglasses

Spaced prong arms, spring loaded toward an initial position, are moved relative to fixed prong arms, against the spring force, to a position for engagement of opposing sections of the eyeglasses frame. The ends of the prong arms are shaped to receive the frame. The spring force causes the prong arms to securely retain the eyeglasses frame. In one embodiment, the moveable prong arms are associated with a coil spring. Movement of the prong arms compresses the spring, which urges the prong arms toward an expanded position. In a second embodiment, the moveable prong arms are leaf springs. The springs flex to permit the frame to be inserted. The ends of the prong arms may be plastic coated to protect the eyeglasses frame.

The present invention relates to clip-on sunglasses and more particularly 
to a mechanism for removeably mounting clip-on sunglasses on eyeglasses 
which is adapted to fit a large number of different size and shape 
eyeglasses configurations. 
Clip-on sunglasses consist of a "front" which includes a metal or plastic 
frame which carries two light attenuating plastic or glass lenses. A 
mechanism is provided for removeably mounting the clip-on sunglasses front 
on eyeglasses. Conventional mounting mechanisms either attach to the 
bridge of the eyeglasses (known as "center bridge mount") or to the 
periphery of the frame. 
In order to be commercially acceptable, the clip-on sunglasses must be 
light in weight, rugged and inexpensive. They must be easy to mount and to 
remove from the eyeglasses. They must also mount without damaging the 
eyeglasses, particularly the lenses. 
One common type of center bridge mounting mechanism utilizes a clamp 
attached to the bridge of the clip-on sunglasses front. The clamp includes 
pairs of opposing clamp parts which are spring loaded toward each other so 
as to frictionally retain the bridge and/or the lenses of the eyeglasses 
therebetween. Examples of this type of clamp are disclosed in U.S. Pat. 
No. 3,575,497 issued Apr. 20, 1971 to Leblanc, U.S. Pat. No. 8,164,749 
issued Nov. 17, 1992 to Shelton and U.S. Design Pat. No. Des 350,359 
issued Sep. 6, 1994 to Friedman. 
These prior art clamp mechanisms have the advantage of being able to fit a 
variety of different eyeglasses styles. However, they have their 
drawbacks. The clamp mechanism consists of several parts which must be 
fabricated and assembled, making them relatively expensive and not very 
reliable. The parts clamp tightly to the lenses, potentially scratching 
the lenses. Moreover, they may obstruct the view partially. 
The peripheral type mounting mechanism are essentially a number of prongs 
fixed along the frame so as to "snap fit" over the eyeglasses frame. One 
example of this type of clip-on mount is illustrated in U.S. Pat. No. 
5,123,724 issued Jun. 23 1992 to Salk. However, this type of mounting 
mechanism must exactly fit each different size and shape eyeglasses frame, 
creating an inventory nightmare or requiring each clip-on to be custom 
made to fit a particular eyeglasses. 
In order to overcome these drawbacks, I have invented a center bridge type 
mechanism for mounting a clip-on sunglasses front which is capable of 
fitting a wide variety of different size and shape eyeglasses and is 
simple, cost effective, reliable. It does not contact or clamp the lenses 
of the eyeglasses, so it cannot scratch them. 
My invention utilizes two sets of prong arms. One set is moveably mounted 
on the assembly such that they can be moved, against a spring force, to a 
position to receive the eyeglasses frame. The spring force causes the 
prong arms to frictionally engage the frame. The lenses of the eyeglasses 
are not clamped or otherwise engaged. 
It is, therefore, a prime object of the present invention to provide a 
center bridge mechanism for mounting clip-on sunglasses designed for use 
with a wide variety of different size and shape eyeglasses. 
It is another object of the present invention to provide a mechanism for 
mounting clip-on sunglasses which cannot scratch or damage the eyeglasses 
lenses or obstruct vision. 
It is another object of the present invention to provide a mechanism for 
mounting clip-on sunglasses on eyeglasses which is simple, reliable and 
inexpensive. 
In accordance with one aspect of the present invention, means are provided 
for mounting clip-on sunglasses on eyeglasses of the type having a frame 
with spaced portions. The sunglasses include a base, fixed prong means 
mounted on the base and prong means moveable relative to said fixed prong 
means from an initial position to a second position to permit engagement 
of the spaced frame portions. Spring means are provided for urging the 
moveable prong means toward the initial position. 
The assembly further includes means for moveably mounting the moveable 
prong means on the base. 
Means are provided for mounting the fixed prong means in a fixed position 
on said base. 
The spring means may include a coil spring. In that case, the second 
position is closer to the fixed prong means than the initial position. The 
spring means may, alternatively, be a leaf spring, in which case the 
second position is remote from the fixed prong means as compared to the 
initial position. 
Preferably, each of the prong means comprises first and second prong arms. 
The end of each prong arm is formed to retain the frame of the eyeglasses. 
In accordance with another aspect of the present invention, apparatus is 
provided for mounting on eyeglasses of the type having a frame with spaced 
positions. The mounting means includes a base affixed to the clip-on 
sunglasses, a fixed prong means mounted on the base and moveable prong 
means mounted on the base. Means are provided for mounting the moveable 
prong means for movement relative to the fixed prong means between an 
initial position and a retracted position. Coil spring means are provided 
for urging the moveably mounted prong means towards the initial position 
to engage the frame of the eyeglasses. 
The moveable prong means includes first and second prong arms moveable as a 
unit. 
The base has an opening. The rod which carries the coil spring is moveably 
received in the opening. The moveable prong arms are mounted on the rod. 
The rod is moveable from an extended position to a retracted position to 
move the moveable prong arms from its initial position to the retracted 
position. 
The base includes first and second spaced, substantially parallel rails to 
which the fixed prong arms are mounted. The rod extends between the rails. 
The bracket which carries the moveable prong arms includes means for 
moveably engaging the rails. 
In accordance with another aspect of the present invention, apparatus are 
provided for mounting clip-on sunglasses on eyeglasses of the type 
including frame portions. The apparatus includes a base with fixed prong 
means and moveable prong means extending from the base. Means are provided 
for mounting the moveable prong means for movement relative to the fixed 
prong means. The moveable prong means comprises a leaf spring for urging 
the moveable prong means toward the initial position. 
The apparatus further includes second fixed prong means and second moveable 
prong means. The second moveable prong means comprise a second leaf 
spring. 
The fixed prong means includes first and second prong arms which extend 
from the base is substantially opposite directions. The moveable prong 
means includes third and forth prong arms extending from the base is 
substantially orthogonal directions.

FIGS. 1-6 illustrate the first (coil spring) preferred embodiment of the 
present invention. The mounting mechanism, generally designated A, is 
affixed to the bridge of the clip-on sunglasses front, generally 
designated B. Mechanism A serves to removeably mount sunglasses front B on 
a pair of eyeglasses, generally designed C. Eyeglasses C consist of a 
frame 10, lenses 12 and a pair of nose pads 14. 
As best seen in FIGS. 3 and 4, mechanism A includes a base 16 fixed to the 
bridge 17 of sunglasses front B by welding or adhesive. Base 16 includes a 
pair of spaced, subtantially parallel rails 18, 20 and a pair of spaced 
brackets 22, 23. Bracket 22 is secured to bridge 17. As seen in FIGS. 5 
and 6, one end of each of the rails 18, 20 is fixed to bracket 22. The 
rails extend through openings in bracket 23 and terminate in ends which 
are bent and affixed to the surface of bridge 17. The intermediate 
portions of rails 18, 20 are spaced a short distance from the surface of 
the bridge 17 to permit bracket 23 to move freely along the rails. Mounted 
on part 22 is a bar 25. Mounted on bar 25, in spaced, generally parallel 
relation, are a pair of fixed prong arms 24, 26. Prong arm 26 is longer 
than prong arm 24. 
A second pair of prong arms 28, 30 are mounted as a unit on a second bar 
32. Bar 32 is carried by bracket 23. Bracket 23 is affixed to one end of a 
rod 34. The other end of rod 34 extends through an opening formed in 
bracket 22, at a point between rails 18 and 20. A cap 35 is situated on 
the end of rod 34 to act as a stop. A compression spring 36 surrounds rod 
34 and extends between brackets 22 and 23. Bracket 23 has spaced openings 
to accept rails 18, 20. 
FIG. 3 shows the prong arms 28, 30 in the initial position, in which 
bracket 23 is furthest from bracket 22 and coil spring 36 is fully 
extended. In order to mount the clip-on, bar 32 and bracket 23 are moved 
toward bar 25 and bracket 22 to compress spring 36 as shown in phantom in 
FIG. 3 such that the ends of prong arms fit between opposing sections of 
the eyeglass frame 10. The clip-on is aligned with the eyeglasses and the 
parts released such that the spring moves bar 32 and bracket 23 toward 
their initial position, causing the prong arms to engage opposing portions 
of frame 10. As seen in FIG. 4, the ends of the prong arms are shaped to 
accept and retain the eyeglasses frame portions. 
Compressing spring 36 by manually moving bracket 23 relative to bracket 22, 
such that the distance between the prong arms is reduced, permits the ends 
of the prong arms to be inserted between the opposing frame portions. 
Releasing the mechanism causes spring 36 to urge rod 34 back toward its 
initial position such that the prong arms are urged to securely retain the 
eyeglasses frame. 
The second preferred embodiment is illustrated in FIGS. 5-8. In the first 
embodiment, the moveable prong arms 28, 30 are mounted on bar 32 for 
movement as a unit, using a single compressible coil spring. By way of 
contrast, the moveable prong arms in the second embodiment are 
individually mounted on the base and comprise leaf springs which permit 
the prong arms to flex to receive the eyeglasses. 
As best seen in FIGS. 7 through 10, mounting mechanism A' consists of a 
base 40 fixedly mounted on bridge 17 of sunglasses front B by welding, 
adhesive or any appropriate method. Extending outwardly in substantially 
opposite directions from base 40 are a pair of fixed prongs, comprising 
relatively rigid, short arms 42, 44. Each of the fixed prong arms 42, 44 
is paired with a moveable prong arm. The moveable prong arms also extend 
from the opposite sides of base 40 but are bent to form approximately a 
90.degree. angle with respect to each other. The moveable prongs arms 
comprise relatively long shafts 46, 48 made of metal so as to form leaf 
springs. Prong arms 46, 48 extend in subtantially orthongonal directions 
in the initial position. 
The ends of fixed prong arms 42 and 44 and of moveable prong arms 46, 48 
are bent to form frame receiving recesses. The recesses of prong arms 42, 
44 are oppositely oriented relative to the recesses in prong arms 46, 48 
so as to retain the eyeglasses therebetween. 
After aligning prong arms 42, 44 such that the frame of eyeglasses C is 
received in the recesses in the prong arms, moveable prong arms 46, 48 are 
moved away from the fixed prong arms (and towards each other) so as to cam 
over the frame portions. Releasing the moveable prong arms causes the leaf 
spring action to urge the prong arms to return to their initial positions, 
so as to securely retain the eyeglasses frame therebetween. 
Preferably, the ends of prong arms 42, 44, 46 and 48 are provided with a 
plastic coating or sleeve 50. This prevents damage to the eyeglasses 
frame. 
It will now be appreciated that the present invention relates to a central 
bridge mechanism for mounting clip-on sunglasses on eyeglasses which can 
be used with a wide variety of different size and shaped eyeglasses to 
mount fashion sunglasses fronts without contacting or damaging the 
eyeglass lenses. Opposing sets of spring loaded prong arms are moveable to 
engage the eyeglasses frame. The spring force retains the clip-on on the 
eyeglasses frame. The ends of the prong arms securely receive the frame. 
While only a limited number of preferred embodiments have been disclosed 
herein for purposes of illustration, it should be obvious that many 
modifications and variations could be made thereto. It is intended to 
cover all of these modifications and variations which fall within the 
scope of the invention, as defined by the following claims: