Bow and spring hinge assembly for eyeglasses

This invention relates to a bow and spring hinge assembly for eyeglasses, in which each bow can be opened beyond a stop-defined position so that the bow can resiliently bear on the head of the wearer. The novel assembly can be used also with slender and thin bows and provides for a transverse bracing for eliminating a transverse backlash between relatively slidable parts. For this reason the assembly is provided in the slider and in the bow end portion with recesses, which face each other and each of which is provided on opposite sides with inwardly facing track grooves, and I-section members are provided, each of which is in sliding contact with the track grooves of both said recesses so that said I-section members hold said bow end portion and said slider together against a transverse separation.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a bow and spring hinge assembly for eyeglasses, 
which assembly permits the bow to be urged beyond a stop-defined position 
so that the bow can resiliently bear on the head of the wearer. 
2. Description of the Prior Art 
German Patent Specification No. 21 15 596 discloses bow and spring hinge 
assemblies which are of the kind described above and comprise a bow-side 
hinge member and a rim-side hinge member, which hinge members are 
pivotally connected, wherein the bow-side hinge member comprises a slider, 
which accommodates and guides a spring and is displaceable against the 
force of said spring along the end portion of the bow, which has a recess 
formed on both sides with track grooves. In that arrangement the slider 
biased by the spring is guided in the end portion of the bow. Such track 
grooves ensure a reliable guidance and prevent a canting and provide for a 
satisfactory covering of the surfaces which are in sliding contact with 
each other. The arrangement has also a small overall height, but the 
slider must be provided with side walls which extend into the bow to 
engage the track grooves therein and add to the width of the assembly. 
Besides, the small backlash which is due to manufacturing tolerances 
cannot be eliminated. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a bow and spring hinge assembly 
which can be used also with narrow bows and which provides for a bias in a 
transverse direction to eliminate a transverse backlash between the parts 
which are displaceable relative to each other. 
In a bow and spring hinge assembly for eyeglasses which assembly permits 
the bow to be urged beyond a stop-defined position so that the bow can 
resiliently bear on the head of the wearer, which assembly comprises a 
bow-side hinge member and a rim-side hinge member, which hinge members are 
pivotally connected, wherein the bow-side hinge member comprises a slider, 
which accommodates and guides a spring and is displaceable against the 
force of said spring along the end portion of the bow, which has a recess 
formed on both sides with track grooves, the object set forth hereinbefore 
is accomplished in that the slider is formed with a recess for 
accommodating the spring and is formed on both sides of its recess with 
track grooves, and the end portion of the bow and the slider are connected 
by I-section members, which extend into the track grooves of the recesses 
in the bow and in the slider so that the side walls of the slider need not 
extend into the bow and the width of the spring hinge can be reduced. 
Specifically, a rear I-section member is provided as a displaceable spring 
abutment, and a forward I-section member is provided as a fixed spring 
abutment. Said rear and forward I-section members are slidably fitted in 
the track grooves of the slider and of the bow end portion. 
To eliminate a transverse backlash between the slider of the bow-side hinge 
member and the end portion of the bow, the recess in the slider may have a 
curved rear end face and the track grooves in the slider may be open-ended 
at said rear end face so that the rear I-section member can be urged by 
the spring against said curved rear end face. The forward I-section member 
may be fixed by a screw to the end portion of the bow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Further details of the bow and spring hinge assembly in accordance with the 
invention are shown in the drawing, which illustrates preferred 
embodiments, and will now be described. 
In the first embodiment shown in FIGS. 1 to 5, the spring hinge comprises a 
bow-side hinge member, which includes two axially spaced apart, coaxial 
hinge eyes 1 and a slider 2, which cooperates with the inner end portion 3 
of the bow through an interposed compression spring 4. The hinge also 
comprises a rim-side hinge member, which is anchored in the rim 6 of the 
eyeglasses and comprises a hinge eye 5, which is disposed between and 
pivoted to the hinge eyes 1 of the bow-side hinge member. 
The slider 2 and the bow end portion 3 are provided each with a recess 7 or 
7a. Said recesses 7 and 7a face each other to constitute a receptacle for 
the spring 4. Each of said recesses 7 and 7a is formed on opposite sides 
with track grooves 8 or 8a, which are open toward each other and receive a 
rear I-section member 9 and a forward I-section member 10. The rear 
I-section member 9 constitutes a displaceable spring abutment for the 
spring 4, which is fitted on a rod 9a carried by the rear I-section member 
9. The rod 9a is engageable with the forward I-section member 10 to limit 
the compression of the spring 4. The forward I-section member 10 
constitutes a fixed spring abutment, which is detachably secured to the 
end portion 3 of the bow. 
The recess 7 in the slider 2 has a curved rear end face 8b and the track 
grooves 8 in the slider 2 are open-ended at said rear end face 8b so that 
the spring 4 can urge the rear I-section member 9 against said curved rear 
end face 8b (FIG. 5), which thus constitutes an abutment for a transverse 
bracing. For this purpose the track grooves 8a formed in the end portion 3 
of the bow extend beyond the curved rear end face 8b, as is shown in FIG. 
3. The forward I-section member 10 is fixed by a screw 10a to the bow end 
portion 3 in the track groove 8a and constitutes a second abutment for a 
transverse bracing so that there will be no transverse backlash between 
the slider 2 and the bow end portion 3 which are slidable relative to each 
other. In FIG. 4 the bow of FIG. 3 is shown in a position to which it has 
been forced beyond its normally open position. FIG. 1 is an exploded view 
showing the components of the assembly and FIG. 2 is a transverse 
sectional view showing the track grooves 8 and 8a in the slider 2 and the 
bow end portion 3. 
The second embodiment shown in FIGS. 6 and 7 provides for a snap action as 
the bow is moved between its normal open position and its closed position. 
That spring hinge also comprises a bow-side hinge member including two 
coaxial and axially spaced apart hinge eyes 11 and a slider 12, which 
cooperates with the end portion 13 of the bow through an interposed 
compression spring 14. The hinge also comprises a rim-side hinge member, 
which includes a hinge eye 15 extending between the hinge eyes 11 and is 
anchored in the rim 16. In that embodiment the eye 15 of the rim-side 
hinge member is provided with a radial cam 15a for producing a snap action 
in a manner which will be described hereinafter. 
In this embodiment, the slider 12 and the bow end portion 13 are also 
formed each with a recess 17 or 17a, which recesses accommodate the spring 
14 and are provided each on opposite sides with track grooves 18 and 18a, 
respectively, which are open toward each other. In said track grooves, a 
rear I-section member 19 and a forward I-section member 20 are slidably 
fitted. The rear I-section member 19 serves again as a displaceable spring 
abutment and carries a rod 19a, for guiding the compression spring 14, 
which is fitted on the rod. The rod 19a is also engageable with the 
forward I-section member 20 to limit the compression of the spring 14. The 
forward I-section member 20 constitutes a fixed spring abutment and is 
detachably fixed to the bow end portion 13 by a screw 20a. In this 
embodiment the forward I-section member 20 carries a rotatably mounted 
roller 21 (FIG. 7) for producing a snap action by a radial engagement with 
the cam 15a of the rim-side hinge eye 15. 
In this embodiment the recess 17 of the slider 12 has also a curved end 
face 18b and the track grooves 18 of the slider 12 are open-ended at said 
curved end face 18b so that the spring 14 can urge the rear I-section 
member 19 against the curved rear end face 18b so that the latter 
constitutes an abutment for a transverse bracing. The forward I-section 
member 20 is fixed by the screw 20a to the bow end portion 13. As a 
result, the forward I-section member 20 constitutes also an abutment for 
the transverse bracing, by which a transverse backlash is eliminated. FIG. 
6 shows the bow in its normal open position and shows in phantom the bow 
in its spring-biased open position and in its closed position. 
To facilitate the insertion of the forward I-section member 20 into the 
track grooves against the force of the stressed spring 14, a forward 
portion of the recess 17a of the bow end portion 13 is covered by a top 
portion defining a tunnel 22 under the hinge eyes 11 so that the I-section 
member 20 can be introduced through the tunnel 22 and can be held back by 
the top portion of said tunnel as the screw 20a is inserted. The fixing 
screw 20a may be replaced by a locking member, such as is shown in German 
Pat. No. 22 42 044. 
FIG. 8 is a sectional view showing the guiding means for a bow-side hinge 
member mounted on a bow of plastic or aluminum. The embodiments described 
hereinbefore are intended for use with a bow made of relatively hard metal 
so that the track grooves can be formed in the end portion of the bow. In 
the embodiment shown in FIG. 8, the slider 12 provided with the track 
grooves 18 is the same as in FIGS. 6 and 7. On the other hand, the track 
grooves 18c are not formed in the bow end portion 23 itself but in a bow 
insert 13a, which has side ribs 13b, which are fixed to the bow 23 in 
retaining grooves 23a formed in the bow, which is made of plastic or 
aluminum. As a result, the track grooves provided in the plastic bow are 
defined by a metallic insert and in an aluminum bow there will be no 
friction between the end portion of the bow and the slider consisting of a 
different metal.