Woven slide fastener stringer

In a woven slide fastener stringer of the type which comprises a row of successively interconnected elongated loops of a plastic filament woven into a longitudinal edge of a stringer tape woven of foundation warp and weft threads, and a pair of groups of upper and lower binding warp threads extending respectively over and under the loops and interwoven with the foundation weft thread, the improvements comprising a gap-filling warp thread extending parallel with and between an outermost one of the upper binding warp threads and the next adjoining upper binding warp thread and also between an outermost one of the lower binding warp threads and the next adjoining lower binding warp thread, and passing alternately over and under the foundation weft thread, thereby tensioning the latter thread to sink substantially halfway between the upper and lower legs of each adjacent pair of loops. Preferably, the outermost upper and lower binding warp threads are disposed in registry with each other to make the foundation weft thread lie substantially perpendicualr to the plane of the fastener stringer between the two outermost binding warp threads. The row of loops thus woven is stably secured in place against angular displacement and held at the proper pitch with respect to individual adjacent loops.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a slide fastener and has particular reference to 
a fastener stringer having a continuous plastic filament spirally formed 
and woven into a longitudinal edge of a stringer tape simultaneously as 
the latter is woven. 
2. Prior Art 
There have been proposed a number of slide fasteners or zippers of the type 
described, which comprise a woven stringer tape and a plastic filament 
woven into a longitudinal edge of the tape, the filament being usually 
formed into a helical coil structure composed of a succession of loops or 
elongated convolutions each having a coupling head, an upper and a lower 
leg and a connecting portion. 
When bent into such helical coil formation, the filament which is thicker 
and harder than the weave yarn tends to yield back, thereby causing the 
fastener stringer to stretch longitudinally and causing the filament loops 
to tilt away from an upright posture with respect to the plane of the 
stringer tape. This displacement of the fastener and filament loops would 
result in irregular pitch of the filament loops, which in turn hinders 
smooth closing and opening operation of the slide fastener. 
A means is disclosed in Japanese Patent Publication No. 46-7018 for 
eliminating the tendency of the individual coil loops to tilt away from 
their desirably upright posture, the means comprising a dense array of 
warp threads along a tape edge into which the filament is woven. This 
prior art, however, still has a drawback in that the fastener stringers 
are susceptible to longitudinal stretch and hence unstable in the 
loop-to-loop pitch of the filament. 
Disclosed in Japanese Patent Laid-Open Publication No. 56-60504 is a woven 
fastener stringer having binding warp threads extending over every two 
coil loops and underlying a foundation weft in double pick between 
adjacent loops thereby forming a pad-like structure between the upper and 
lower legs of the loops so as to improve resistance to tortion of the 
filament loops and to stabilize the inter-loop pitch. This stringer 
structure having binding warp threads bundled up by weft threads would 
become extremely thick and heavy and hence less flexible. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a woven stringer for a 
slide fastener having a row of successively interconnected elongated loops 
or convolutions formed from a plastic filament and woven into a stringer 
tape, the row of loops being stably secured in place against tilting or 
angular displacement and held at the proper pitch with respect to 
individual adjacent loops. 
It is another object of the invention to provide a woven fastener stringer 
having a row of elongated loops secured to the tape in such a manner that 
the loops may assume improved posture for coupling engagement. 
According to the invention, a woven slide fastener stringer comprises a row 
of successively interconnected elongated loops of a plastic filament woven 
into a longitudinal edge of a stringer tape woven of foundation warp and 
weft threads, a pair of groups of upper and lower binding warp threads 
extending respectively over and under the loops and interwoven with the 
foundation weft thread, and a gap-filling warp thread extending parallel 
with and between an outermost one of the upper binding warp threads and 
the next adjoining upper binding warp thread and also between an outermost 
one of the lower binding warp threads and the next adjoining lower binding 
warp thread, and passing alternately over and under the foundation weft 
thread, thereby tensioning the latter thread to sink substantially halfway 
between the upper and lower legs of each adjacent pair of loops. 
Preferably, the outermost upper and lower binding warp threads are 
disposed in registry with each other to make portions of the foundation 
weft thread lie substantially perpendicularly to the plane of the fastener 
stringer. The row of loops thus woven is stably secured in place against 
tilting or angular displacement and held at the proper pitch with respect 
to individual adjacent loops. 
Other advantages and features of the present invention will become manifest 
to those versed in the art upon making reference to the detailed 
description and the accompanying sheets of drawings in which preferred 
structural embodiments incorporating the principles of the present 
invention are shown by way of example.

DETAILED DESCRIPTION 
A fastener stringer generally designated 10 constitutes one part of a pair 
of identical stringers for a slide fastener. The stringer 10 includes a 
woven stringer tape 11 having a generally flat web section 11a (only 
partly shown) defining a major dimension of the stringer tape 11 and a 
filament woven section 11b defining a longitudinal edge portion 12 of the 
stringer tape 11 into which a filament 13 of plastic material is laid in 
double pick and woven in the form of a row of successively interconnected 
elongated loops each of which serves as a fastener coupling element. 
Each loop or elongated convolution 14 of the filament 13 has a coupling 
head 14a at one end thereof, an upper leg 14b and a lower leg 14c 
extending from the head 14a in a common direction and a heel portion 14d 
remote from the head 14a connected to a next adjacent one of the 
successive loops 14. The coupling head 14a is dimensioned to releasably 
couple with a corresponding head of a loop 14 on a mating stringer to open 
and close the fastener in a well known manner. 
The web section 11a of the stringer tape 11 may be of any known design 
having foundation warp threads 15 and a foundation weft thread 16 
interwoven in a variety of patterns, which will require no further 
explanation as this has no direct bearing upon the invention. 
In the filament woven section 11b of the stringer tape 11, there are 
provided a group of upper binding warp threads 17 extending in parallel 
longitudinally of the stringer tape 11 and overlying the upper legs 14b of 
successive filament loops 14, and a group of lower binding warp threads 18 
extending in parallel longitudinally of the stringer tape 11 and 
underlying the lower legs 14c of successive loops 14, both groups of 
binding warp threads 17, 18 running as a whole substantially along a 
straight path at the region of the legs 14b, 14c which extends 
substantially from the midpoint of each of the upper and lower legs 14b, 
14c to the heel portions 14d. The foundation weft thread 16 is laid in 
double pick and interwoven with the foundation warp threads 15 to form the 
web section 11a. In the filament woven section 11b, the foundation weft 
thread 16 is interwoven with the upper and lower binding warp threads 17, 
18 to form loops in the spaces between each adjacent pair of loops 14 or 
in each of successive ones of inter-loop spaces 19. 
A pair of gap-filling warp threads 20, which is laid preferably in 
juxtaposition as shown, extends parallel with and between a first or 
outermost upper binding warp thread 17a and a second or next adjoining 
upper binding warp thread 17b and also between a first or outermost lower 
binding warp thread 18a and a second or next adjoining lower binding warp 
thread 18b, and passes alternately over and under the continuous 
foundation weft thread 16 in the inter-loop spaces 19 and underlie the 
lower legs 14c of the filament loops 14. The foundation weft thread 16 is 
tensioned by the gap-filling threads 20. Since the gap-filling warp 
threads 20 underlie the lower legs 14c and the foundation weft thread 16 
but do not overlie the upper legs 14b, upper portions of the respective 
loops of the foundation weft thread 16 are drawn to sink almost halfway 
between the upper and lower legs 14b and 14c in the interelement spaces 
19, as shown in FIG. 2. As a result, the spaces 19 between adjacent loops 
14 are substantially closed to retain the position of all the loops 14 
substantially upright or at a right angle to the plane of the fastener as 
desired for smooth coupling operation of the fastener. The first upper 
binding warp thread 17a is disposed substantially in registry with the 
corresponding first lower binding warp thread 18a so that the portions 16a 
of the foundation weft thread 16 which span between these warp threads 17a 
and 18a are oriented to lie substantially perpendicularly to the plane of 
the fastener stringer 10, thereby clearly defining an open area required 
for smooth and accurate coupling engagement of the coupling heads 14a of 
adjacent loops 14. 
A plurality of loop-clamping warp threads (four in the illustrated 
embodiment) 21 are provided for clamping interconnected successive loops 
14 of the coupling filament 13 in place against displacement which would 
otherwise take place when the fastener is subjected to bending or other 
external stresses. As better shown in FIG. 2, the loop-clamping warp 
threads 21 bring the upper and lower legs 14b, 14c of each loop 14 closely 
together so that the loops 14 may assume stable posture with respect to 
the stringer tape 11. The loop-clamping warp threads 21 extend parallel 
with and between the remaining upper and lower binding warp threads 17, 
17b and 18, 18b except the outermost two threads 17a, 18a, and alternately 
overlie the upper legs 14b and the foundation weft thread 16 and underlie 
the lower legs 14c and the foundation weft thread 16 so as to form a 1/1 
weave structure with the filament 13 and a 2/2 weave structure with the 
foundation weft thread 18. The upper loop-clamping warp thread 21 and the 
lower loop-clamping warp threads 21 extend in a symmetric pattern. These 
weave structures provide a stable loop-to-loop pitch of the filament loops 
14. 
A plurality of anchoring warp threads (two in the illustrated embodiment) 
22 underlie the lower legs 14c of the loops 14 adjacent to the coupling 
heads 14a and are interwoven with the foundation weft thread 16 to form a 
supporting anchor for the filament loops 14 to prevent the latter from 
leaning downwardly away from the plane of the fastener stringer 10. 
FIG. 3 shows a modified woven fastener stringer 30 according to the 
invention which is substantially the same as the stringer 10 shown in 
FIGS. 1 and 2, except that there is provided one additional lower binding 
warp thread 18b' disposed between the outermost lower binding warp thread 
18a and the next adjoining binding warp thread 18b. 
As it appears obvious from the scope of the appended claims and to those 
skilled in the art, there may be made various changes and modifications in 
the specific embodiments herein shown and described. As for an example, 
the number of upper and lower binding warp threads 17 and 18 or clamping 
warp threads 21 may be varied according to the size of the slide fastener 
desired.