Adjustable retainer for eyeglasses

An adjustable retainer for eyeglasses that have a pair of temple bars. The retainer includes two cords of preferably the same length, one of which is attached to the right temple bar and the other of which is attached to the left temple bar. In one embodiment, the cords are attached by inserting a loop in the end of the cord partially through a hole in the end of the temple bar, and then passing the tail end of the cord through the loop and pulling the cord to tighten the loop around the temple bar. In another embodiment, two elastic cords, each having an enlargement at one end, are pulled through their respective temple bar holes so that the enlargement is held against the outer surface of the hole. In both embodiments, the tail ends of the cords are inserted through a cord holder, which is preferably a cord lock, and secured together to form a stop for the cord holder.

TECHNICAL FIELD OF INVENTION 
The present invention relates generally to retainers for eyeglasses, and 
particularly to an adjustable elastic retaining cord system for eyeglasses 
having a pair of temple bars. 
BACKGROUND OF THE INVENTION 
A number of different retaining systems have been devised for preventing 
eyeglasses from slipping or falling off. Some of these systems rely on 
resilient straps to hold the eyeglasses securely on the wear's head during 
sports and other physical activities. Some strap systems may permit 
limited adjustability of the strap tension by means of a buckle, hook and 
loop fasteners, or by allowing the user to adjust the point of attachment 
to the eyeglass temple bars. Other eyeglass retention systems rely on 
single lengths of cord or tubular material that are attached to the temple 
bars. The materials used in the retaining cords and tubes, and the 
elasticity of those materials, vary considerably. Some of the retention 
systems that use cords and tubes, unlike the systems that use flat straps, 
use a long cord with a slider that frictionally engages the doubled cord 
behind the head. The slider allows the user to adjust the cord tension and 
to release it entirely in order to lower the eyeglasses to hang loosely 
below the neck and at a preferred distance below the neck. 
A problem encountered by all of the prior art eyeglass retention 
systemsconcerns the means of attaching the retention straps, cord or 
tubing to the eyeglass temple bars. Some eyeglass retention systems rely 
on sleeves that slide over the end of the temple bar, as shown in U.S. 
Pat. No. 5,575,042 to Kalbach (1996). Sleeves that fit over the portion of 
the temple bar in front of the downwardly curving section of the temple 
bar are shown in U.S. Pat. No. 4,133,604 to Fuller (1979), U.S. Pat. No. 
5,157,425 to Liu (1992), and U.S. Pat. No. 5,087,118 to Gill (1992). A 
number of systems rely on elastomeric rings and loops of various 
configurations that are attached to each end of a retainer cord and 
frictionally engage the temple bars. Examples of such systems are 
disclosed in U.S. Pat. No. 3,874,776 to Seron (1975), U.S. Pat. No. 
4,790,646 to Seron (1988), U.S. Pat. No. 4,965,913 to Sugarman (1990), 
U.S. Pat. No. 5,092,668 to Welch, et al. (1992), U.S. Pat. No. 5,655,264 
to Davancens, et al. (1997), and U.S. Pat. No. 5,805,262 to Deveney 
(1998). Other systems employ loops that are formed in the end of the 
retainer cord and are tightened around the temple bar by pulling the cord 
through a sleeve, as shown, for example, in U.S. Pat. No. 3,827,790 to 
Wenzel (1974), and U.S. Pat. No. 4,783,164 to Heiberger (1988). U.S. Pat. 
No. 5,507,075 to Tillstrom (1996) discloses a loop/spring combination 
whereby the loop is held onto the temple bar by the compression of the 
spring. 
Another method of attaching a retention cord to the temple bars is 
disclosed by U.S. Pat. No. 5,786,882 to Satterthwaite (1998), which shows 
eyeglass temple bars with forward-facing slots in the ends of each temple 
bar that engage a continuous elastic band, such as a rubber band, or each 
end of a single length of elastic band material. U.S. Pat. No. 4,603,951 
to Beck, et al. (1986) shows an eyeglass frame with a hole at the end of 
one temple bar and a longitudinal opening in the end of the other temple, 
so that an elastic band can be inserted through the holes, with an 
enlarged end of the cord engaging the hole in the first temple and the 
other end engaging the longitudinal opening in the second temple in a 
self-locking manner. U.S. Pat. No. 4,761,068 to Star (1988) shows two 
retaining straps having hook and loop fasteners on one end and 
mushroom-shaped tips on the other end that are inserted through holes in 
the temple bars and secured with small C-shaped clasps. A different 
approach is disclosed in U.S. Pat. No. 4,976,531 to Kahaney (1990), which 
shows a strap assembly that, in one embodiment, snaps into suitably-sized 
holes in the end of each temple bar. 
U.S. Pat. No. 3,728,012 to Downey (1973) discloses an eyeglass retention 
system wherein the retaining strand is a plastic monofilament line that 
passes behind the head and through openings in the temple bars. The strand 
is tensioned by pulling one or both of its ends, and the high friction of 
the strand against the openings holds the eyeglasses in the desired 
position. U.S. Pat. No. 5,655,263 to Stoller (1997) discloses a retaining 
cord with ends that pass outwardly through holes in each temple, with each 
end then being inserted through a friction block and knotted. The 
eyeglasses can be held snugly against the face by pulling each end knot 
laterally and moving the friction blocks against their respective temple 
bar, with the result that the cord ends hang down on both sides of the 
neck behind the ear. To lower the eyeglasses, the friction blocks are 
moved toward the ends of the cord. This system also calls for the cord to 
have sufficient surface texture to hold the eyeglasses at the desired 
level below the neck by the friction of the cord against the inside 
surface of the holes. 
Yet another approach to securing the retainer cord to the temple frames is 
shown in U.S. Pat. No. 5,917,576 to Falco (1999), which discloses a 
retaining band comprised of a single length of polymeric material that is 
bonded to the end of each temple bar. The polymeric retaining band can be 
permanently stretched by the user to customize its length within the 
elongation limits of the material. U.S. Pat. No. 5,541,676 to Pallat 
(1996) eliminates the temple bars altogether and shows the retainer cords 
being attached to the temple bar hinges on the each side of the front 
lens-containing portion of the eyeglass frame. U.S. Pat. No. 5,926,855 to 
Brodbeck (1999) shows a system for securing goggles of the type used by 
swimmers that involves threading a single length of elastic shock cord 
through a hole on each side of the goggle, and then inserting the ends of 
such single cord through a spring-loaded cord lock. This arrangement 
results in a double strap system around the back of the head and permits 
strap tension to be adjusted by moving the cord lock. 
There are a number of disadvantages and limitations associated with the 
retaining systems disclosed by the prior art, particularly where 
extended-wear comfort, appearance, and manufacturing cost are all 
important considerations. The goggle-type bands and straps are well suited 
for applications where a snug fit over short periods is required, but they 
tend to be too tight and uncomfortable for extended or casual wear. These 
strap systems also do not allow the eyeglass to be lowered to hang on the 
chest, as do some of the adjustable cord retainer systems. However, the 
braided cords and tubular bands typically used in adjustable cord systems 
can feel heavy and bothersome on the neck and shoulders. 
Furthermore, the means disclosed by the prior art for attaching the 
retaining systems to the temple bars also have significant drawbacks. The 
attachment rings and sleeves that fit over the temple bar can affect the 
way the temple bar feels as it passes over and behind the ear, and thus 
can be annoying to many eyeglass wearers. The elastomeric rings can be 
pulled off inadvertently if they have not been tightly secured or if the 
temple bar lacks a substantial flare at the end to help keep the ring on 
the bar. A number of popular sunglass styles have a sleek, minimalist 
appearance with narrow temple bars that have very little, if any, flare at 
the end. The prior art eyeglass retainers with enlarged ends that engage 
holes in the temple bars have the significant limitation of not working 
with holes that exceed a certain maximum size. Eyeglass retainer systems 
that adjust by pulling the ends of the retainer strands laterally from the 
temple result in unsightly and bothersome strand ends hanging down behind 
each ear. Furthermore, the complexity of some retention systems renders 
them impractical from a manufacturing cost standpoint. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an eyeglass retention 
system that is light, comfortable and attractive, and that eliminates 
annoying and uncomfortable rings, sleeves, and loops that attach around 
the temple bar of the eyeglass frame. It is also an object of the present 
invention to provide a means of attaching the cord to the temple bars that 
is both extremely secure and unobtrusive, and which does not affect the 
feel of the temple bar as it passes behind the ear. 
Yet another object of the present invention is to provide a convenient 
method of adjusting the tension of the retention cords to suit individual 
preference. It is also an object of the present invention to provide a 
system that will prevent slippage of eyeglasses during vigorous physical 
activity. Another object is to allow the eyeglasses to be suspended 
comfortably below the neck, at a distance easily adjusted by the user, 
when the eyeglasses are not being worn. 
It is also an object of the present invention to provide an eyeglass 
retention system that has a sleek, minimalist appearance that is in 
keeping with many popular styles of sunglasses and safety glasses. 
It is also an object of the present invention to provide an eyeglass 
retention system that is economical to manufacture, and that works well 
with a number of popular styles of safety glasses, which have holes at the 
ends of the temple bars. A further object is to provide a system that can 
be easily made to work with virtually all eyeglass temple bars by simply 
drilling small holes in the ends of each temple bar.

DETAILED DESCRIPTION OF THE INVENTION 
As illustrated in FIG. 1, the eyeglass retainer of the present invention 
comprises a first retainer cord 26 that attaches to the end of a right 
temple bar 10 and a second retainer cord 28 that attaches to the end of a 
left temple bar 12. In the embodiment illustrated in FIG. 1, the retainer 
cords are attached to the temple bars by inserting loops 18, 20 that have 
been tied in one end of each retainer cord partially through their 
respective holes 14, 16 in the ends of the temple bars. The tail ends 34, 
36 and the knots 22, 24 used to tie the loops are passed through their 
respective loops and pulled tight. In the preferred embodiment, the tail 
ends 34, 36 of the two cords are then passed through the aligned holes in 
a springably released cord lock 30 and tied together so that the resulting 
knot 32 forms a stop for the cord lock. FIG. 2 shows the method for 
securing the looped end of the retainer cord to the hole in end of the 
temple bar. FIG. 3 shows the two side views of the finished attachment of 
the retainer cord to the temple bar after the loop has been pulled snugly 
against the temple bar. Although FIGS. 2 and 3 show the direction of the 
insertion of the loop 18 into the hole 14 in right temple bar 10 being 
from the outside of the temple bar toward the inside, the direction of 
insertion of the retainer cord loops is not critical. A variety of 
materials can be used for the retainer cords of this embodiment, but the 
preferred material is elastic cord with a rubber core and a stretchable 
fabric covering. In particular, round elastic cord with a diameter of 
approximately 1/16" has been shown to work very well. 
The loops on each retainer cord may be formed by any of a number of 
conventional methods, but the preferred method is by means of a simple 
overhand knot or a so-called "perfection loop" knot, which is often used 
to tie loops in fishing line. The loops 18, 20 should be made large enough 
to allow their respective knots 22, 24 to pass through when the retainer 
cord is pulled tight. The tag end of the knots should be trimmed. If the 
preferred elastic cord material is used, sufficient heat should be applied 
to the trimmed tag end to melt the end of the fabric covering to prevent 
it from fraying. 
FIG. 4 shows another means of attaching the retainer cords to the temple 
ends, which is well-suited for temple ends having a narrow profile that 
will not accommodate a hole large enough for a loop to pass through. In 
this embodiment, the retainer cords have one end that is enlarged, 
preferably by means of an overhand knot 40. Other methods of enlarging one 
end of each cord will also work, but an overhand knot has the advantage of 
being very simple and inexpensive to execute. As with the loop knot, the 
tag end of the overhand knot should be trimmed and heated to prevent 
fraying. The tail end of the cord is passed through a hole 16 in the 
temple end, and then pulled through the hole until the knot or other 
enlargement rests against the surface surrounding the hole. Preferably, 
the cord is fed through the hole from the outside of the temple bar, so 
that the knots do not contact the the neck when the eyeglasses are being 
worn. FIG. 5 is a side view from the outside of the left temple bar 12 
showing the knot 40 pressed against the temple bar surface around the 
hole. For the embodiment illustrated by FIGS. 4 and 5, the retainer cord 
is a round, small diameter elastic cord. A combination of a 1/16" diameter 
elastic cord and a 3/32" hole diameter has been shown to work well in this 
application. Most narrow profile temple bars will accommodate a hole of 
this size, and 3/32" drill bits are commonly available, making it easy for 
temple bars that lack holes in the ends to be adapted for use with this 
embodiment of the present invention. A 1/16" elastic diameter cord 
securely retains the eyeglasses and yet is very light and comfortable. The 
narrow cord profile also fits well with the sleek design of many popular 
styles of sunglasses and safety eyeglasses. 
FIG. 6 is an illustration of the tail ends 34, 36 of the retainer cords 
secured together by means of the preferred overhand knot 32, which also 
serves as a stop for a cord lock 30, the preferred cord holding means. One 
advantage with using an overhand knot as a cord stop is that it can be 
relatively easily untied in order to remove the retainer cords if desired. 
The knot or other cord securement means should be large enough to prevent 
the cord lock or other cord holding means from easily passing over the 
securement means. Two cord lock models that have been shown to work well 
in this application are the Ellipse manufactured by ITW Nexus and the 
Pop-Lock manufactured by National Molding Corporation. These cord locks 
are both quite small and lightweight and have a similar elliptical profile 
when viewed from the top or bottom. This shape gives the sides of the cord 
lock a somewhat flatter contour, which is comfortable when the cord lock 
is pulled against the back of the head. The even smaller and lighter 
Posi-Grip cord lock from National Molding Corporation has an all-plastic 
construction and also works satisfactorily. It can be appreciated that 
other means of adjusting and maintaining the tension of the retainer 
cords, such as decorative beads that frictionally engage the first and 
second cords, will also work. However, it can also be appreciated that the 
frictional engagement of beads and rings against the retainer cords is 
typically not as secure as that provided by a spring-loaded cord lock. 
Preferably, the length of each retainer cord from the hole in the temple 
bar to the knot at the tail end should be approximately the same, so that 
the cords hang evenly. The distance from the end of the temple bar to the 
knot tying the tail ends together can vary considerably, provided that 
such distance is sufficiently long to allow the eyeglasses to be easily 
removed and suspended comfortably below the neck when the cord holder is 
positioned against the knot. 
The looped-end retainer cords will readily work with a number of popular 
safety eyeglasses that have temple bars with holes molded into the ends. 
For example, the looped-end embodiment works without any adaptation with 
several models of safety eyeglasses manufactured by UVEX Safety, a leading 
manufacturer of safety glasses, and with a number of popular models from 
other safety eyeglass manufacturers. Moreover, when the preferred 1/16" 
diameter elastic cord is used, virtually any eyeglasses with temple bars 
can easily be adapted to work with an embodiment of the present invention 
by drilling 1/8" holes (for looped-end retainer cords) or 3/32" holes (for 
knotted-end retainer cords) in the ends of each temple bar. 
While the present invention has been described with respect to specific 
embodiments, it is to be understood that other modifications and changes 
may be made to the disclosed embodiments without departing from the spirit 
and scope of the invention as defined by the following claims.