Title of Invention

THREAD DRIVE MACHANISM CONTROLLED IN A MANNER DEPENDING ON THE DETERMINED THREAD TENSION

Abstract The invention relates to a device for a stitching or sewing machine, said device comprising a thread drive mechanism (10) with a roller (11) mounted to rotate about an axis, which may be driven by a drive unit in both directions about the axis thereof. On turning said roller in one direction, an upper thread (3) for thread feed or loop formation Is wound off a feed spool (4) and by rotating the roller (11) in the opposite direction, the upper thread is pulled back (thread withdrawal) and thus drawing the stitch or loop. During the stitching or sewing process a measuring device (8) measures the tension in the upper thread and the device controls the thread drive mechanism depending on the determined thread tension.
Full Text The present invention relates to a device for a stitching or a sewing machine
comprising a thread driving mechanism hiving a roller mounted for rotating
about an axis, said roller driven by the drive unit in both directions about the
axis thereof; and a feed spool for winding off an upper thread for thread feed
or loop formation, by turning said roller in one direction, and pulling back the
upper thread for thread withdrawal by rotating the roller in the opposite
direction, thus drawing the stitch or loop; as well as a process using the device
according to the invention.
A device is known from EP-PS0014897, in the case of which a roller looped by
the needle threads is equipped with a drive, which pre-sets the advance and pull
back direction of the roller independently of the thread tension and in the case of
which the thread guides are also omitted, because the thread length released
and again withdrawn by these is likewise advanced and pulled back by the driven
roller. The function of the mechanism indicated in this document is limited to
simulating the stitching process in such a way as known from conventional
shuttle sewing machines according to DE-PS 3416266. The process is further
based on creating a thread tension in the needle thread during the stitching
process. In particular, EP-PS 0014897 discloses that the completed stitch is
tightened by reversing the roller after the stitch formation, whereby the needle
thread is tensioned (page 4, column 6, Iines 25 to 28). This process again leads
to stress in the needle threads, which limits the operating speed and results in
the occurrence of thread breakages. In the case of the device described in EP-
PS 0014897, there is no control regarding possible thread breakages in particular
of the upper or lower thread . Rather, the thread feed and in particular the
thread withdrawal are permanently pre-set by the control system. The thread
tension is not checked during the stitching process in the case of this
device. For example, if disturbances arise during the stitching process.
then the force-actuatod thread withdrawal automatically
leads to thread breakage.
EP 0666351 discloses a process and a device for embroidering
on a shuttle sewing machine, in the case of which a thread
guide and a feed unit supply the length of thread necessary
for the needle to penetrate the fabric, for loop formation
for the shuttle to pass through the loop and the thread
length to be applied or. the embroidery foundation for stit
formation, whereby the needle thread is kept virtually
stress-free curing the entire stitch formation and the
stitch is only tightened due to the wind-off force of the
shuttle thread. The process and device described in EP
0666351 cannot be transposed to a stitching or sewing
machine, in the case of which the upper thread must be
always pulled back or tightened by the thread withdrawal for
the loop or stitch formation and thus is continually under
stress.
DE 3839733 describes a stitch-forming machine with a sensor
to measure the tension contained in a thread, commising a
control device via which the tension is evaluated during
individual phases of the stitch formation. By means of this
device, the tension in the needle thread can be easily
determined/ whereby if there is too much tension the stitch
formation process is interrupted and suitable counter
measures can be taken.
The object of the present invention is to further develop a
stitching or sewing machine to the effect that the loop or
stitch formation in the individual working phases of the
stitching or sewing machine is optimized by optimum thread
tension. Furthermore, it is proposed that a stitching or
sewing machine is further developed to the effect that the
thread feed and in particular thread withdrawal are
optimized, so that in particular fewer thread breakages
occur.
This object is ingeniously achieved with a device according
to the features of claim 1. Further advantageous embodiments
are clear from the features of the dependent claims 2 to 28.
Furthermore, a process is claimed using a device according
to claims 1 to 28, which serves to execute an optimiz
stitching or sewing process. Advantageously, the process
according to claim 29 is further expanded by the features of
claims 30 to 33,
Advantageously, the device measures the tension in the upper
thread during thread withdrawal by means of measuring
device, whereby the measured tension is considered by the
control system of the device, meaning that it is checked
whether the stitch process is being properly executed. If a
deviation in the thread tension is detected, the control
system of the device or the stitching or sewing machine
determines whether the thread tension is too much or too
little for the particular stitching or sewing process.
Depending on the evaluated thread tension signal, the thread
drive' mechanism is controlled accordingly during thread
withdrawal. Thus, advantageously, thread withdrawal can be
terminated for example, if the level of the determined
thread tension exceeds a calculated pre-set tension
threshold value. This tension threshold value, for example,
can be variable and advantageously depends on the thread to
be stitched (type and strength), the foundation to be
embroidered as well as on the kind of stitch. The stitching
or sewing machine can also be stopped with the thread

withdrawal, so that, for example, the operatives can
manually rectify any problems arising during the stitching
process. Likewise, the sewing or stitching machine can begin
the next stitch formation immediately after the current
stitching process has finished. If the thread threshold
value is exceeded during this stitch or loop formation, the
sewing or stitching machine can also be stopped by the
control system.
It is equally possible to increase the speed of the thread
advance so that the thread tension is reduced. Likewis , it
is possible to wind off less thread, if too much upper
thread is present when the lower thread is fed through the
loop formed by the upper thread, so that the thread tennson
in the upper thread assumes higher values. The direct
control of thread advance or thread withdrawal ensures that
the speed of the thread advance and thread withdrawal and
the speed of the needle are generally coordinated with one
another, and that too much tension does not arise in the
upper thread. Thus, for example, it is possible that after
the loop has been formed, the upper thread is shortened by
knot formation, so that less thread has to be pulled back in
order to tighten the loop or the stitch with the necessary
tension. In the event of such an occurrence with
conventional stitching or sewing machines, a thread breakage
would inevitably occur, unless these comprise a thread
tension measuring device according to DE 3839733, whereby
this occurrence would then inevitably lead to stoppage of
the machine. Since the thread tension-measuring device
according to DE 3839733 would only emit a signal that the
maximum permissible upper thread tension had been exceeded,
so that the stitching machine would be inevitably stopped.
The device according to the invention however, through
direct control of thread withdrawal, would pull back less
thread, so that the permissible tension in the upper thread
is not exceeded, thereby preventing thread breakage and
stoppage of the stitching or sewing machine. At the same
time, the optimum thread upper tension can be obtained
during the loop or stitch formation by means of the device.
Advantageously/ the optimum thread upper tension can be
controlled by means of an appropriate regulation algorithm.
Advantageously, the device-also reduces the speed/ at which
the upper thread is withdrawn, if the thread upper tension
approaches a calculable or pre-definable tension threshold
value. Thereby good regulation characteristics are obtained
and thread breakage is reliably prevented.
Advantageously, it is possible with the device according to
the invention to detect upper thread and also lower thread
breakages. This is due to the fact that during the entire
stitching or sewing process, the tension of the upper thread
just stitched is monitored by the device. As a result, it is
possible to recognize whether the tension in the upper
thread exceeds or falls below certain threshold values at
certain times during the stitch or loop formation.
Thus, on the one hand, it is possible that, during the
passage of the lower thread through the thread loop produced
underneath the stitching foundation by means of the shuttle,
the thread tension does not exceed an inadmissible level. If
the thread tension exceeds the tension threshold value for
example by means of the thread drive mechanism further
thread can be made available, so that the loop is
sufficiently large for the shuttle with the lower thread
spool located in it to safely pass through the loop.
Furthermore, in this case the maximum permissible thread
length can be considered. If, for example, further thread is
wound off by the thread drive mechanism to reduce the thread
upper tension, it must be ensured that this does not
continue for an infinitely long period. Rather, it must be
ensured that the stitching process is interrupted after a
certain length of additional thread, since a critical error
has arisen.
On the other hand, lower thread breakages can be reliably
detected if a certain tension threshold value is not reached
when a first tension peak occurs. Thus, the upper thread is
slightly tensioned by pulling the lower thread through the
loop formed by the upper thread, so that the tension in the
upper thread increases while being pulled through in order
thereafter to drop again. If the tension threshold value has
not been exceeded, then this is rated as thread breakage.
Likewise, however, this can also mean that too much thread
has been advanced for the loop formation. The latter case
can be determined, for example, by thread withdrawal within
the time frame, in which the shuttle passes through the loop
of the upper thread. If the tension does not increase within
this time frame, then it can be concluded that the lower
thread has broken.
Advantageously, the control electronics of the device i.e.
the sewing or stitching machine, in the event of any of the
aforementioned scenarios in each case checks the steps taken
to resduce the tension in the upper thread for their
plausibility.
Advantageously, the thread drive mechanism of the device
according to the invention serves to advance or transport
several upper threads of a multi-head sewing or stitching
machine. For this purpose, the roller turned by the drive
can be moved parallel to the surface of the stitching
foundation and pressed against rollers, around which the
individual upper threads are fed separately in each case, so
that the individual rollers looped by the upper threads can
be rotated alternatively after one another by means of the
roller. By changing the rotating direction of the driven
roller either thread is advanced or, however, the upper
thread is withdrawn.
A further advantageous configuration of the device according
to the invention arises if a thread reversing device is used
to measure the tension of the upper thread just stitched or
sewn. For this purposs, at least one sensor records the
deformation or excursion of the thread reversing device from
its original position. From the amount of deformation or
excursion control electronics can easily determine the
tension in the upper threaa currently being sewn or
stitched. Since all upper threads of the multi-threa
stitching or sewing machine are reversed by the thread
reversing mechanism, advantageously only a few or only one
sensor is needed to determine the respective thread tensions
of the individual upper threads being stitched alternatively
after one another.
Advantageously, the thread reversing mechanism is a U-shaped
part, which is fixed to the stitching head at its two ends
in each case via intermediate parts. The intermediate parts
can be configured at an angle, so that the reversing
mechanism is somewhat offset from the front plate of the
stitching head and thus leverage forces can be used to bend
the angular brackets or the one angular bracket.

Advantageously, this is formed with a thin wall in one area
for easier bending of an angular bracket. Advantageously, in
this thin-walled area the deformation can be recorded by
means of wire strain gauges. Likewise, it is conceivable
that pressure sensors as, for example, piezo elements are
used, which pick up the thrust forces arising at the
junction or contact points.
Various exemplary embodiments of the device according to the
invention are described in detail below on the basis of
drawings, wherein:
Fig. 1 shows a perspective view of a first possible
embodiment of the device according to the invention;
Fig. 2 shows a second possible configuration of the device
according to the invention;
Fig. 3 shows a detailed view of the thread drive mechanism;
Fig. 4, 5 and 6 show tension gradients in the upper thread
during various stitching scenarios;
Fig. 7 shows a perspective view of a stitching head with a
thread reversing mechanism to measure the tension in an
upper thread;
Fig. 8 shows an exploded view of the embodiment according to
Fig. 7;
Fig. 9 shows a sectional view through a thread reversing
mechanism according to the invention to measure the tension
in an upper thread.
Fig. 1 illustrates a sectional view of a stitching machine.
The stitching head 1 comprises a needle drive mechanism for
several stitching needles 2, which can selectively stitch an
upper thread 3 with their tips 2a. Fig. 1 only shows the
component parts relevant to the function of the device. The
upper th.ead 3 is guided via reversing devices 5a, 5b, 5c,
5d and 5e to the stitching needle 2. The stitching thread 3
is wound off from the feed spool 4 over the reversing
mechanism 5a, 5b and 5c and guided through the respective
eyes 5a, 5b and 5c to the respective drive rollers 6.
The stitching thread in this case loops once or several
times the drive roller 6 assigned to it and then leaves the
roller 6 in the direction of the thread guide mechanism 5d,
through the eye of which it is further taken in the
direction of the thread tension sensor 8, in order then to
pass through the thread guide 5e or its eye 5e in the
direction of the needle tip. Thread feed or thread
withdrawal is ensured by means of drive 10 and drive roller
11. The drive 10 can rotate the roller 11 in both directions
of rotation around pre-set angles, so that pre-determined
thread lengths are supplied (thread feed) or pulled back in
the direction of the spool (thread withdrawal). For thread
withdrawal, thread bobbins not illustrated or a winding
mechanism for the feed spool 4 are provided. The drive 10
including drive roller 11 is rotatably mounted so that it
can be optionally swiveled against one of the rollers 6. For
this purpose, the stitching head 1 can also be moved
parallel to the axis of the rollers 6. If another upper
thread has to be stitched, the drive mechanism 10, 11 is
swiveled away from the roller 6 last driven in each case and
then the stitching head 1 is moved parallel to the axis of
the rollers 6, until the drive roller 11 is in the vicinity

of the driven roller 6 of the stitching or sewing thread
next to be stitched, in order thereafter to be pressed
lightly or swiveled against the roller 6. The respective
thread is wound off from the feed spool 4 and advanced by
frictional force for loop formation or withdrawn by means of
the other direction of rotation in order to complete the
loop formation or stitching process.
During the current stitching operation, the thread tension
of the upper thread being stitched in each case is
determined, in order to control thread withdrawal depending
on the determined tension.
The device according to Fig. 2 is expanded by additional
thread take-up levers, whereby the thread tension can be
additionally controlled or regulated during thread
withdrawal by adjusting the respective thread cake-up lever
12. Functionally similar component parts compared to tne
device according to Fig.l are described with the same
reference numbers. Due to the additional use of the thread
take-up levers 12, a thread reversing mechanism 13, 14 is
needed, through the eyes 14 of which the upper threads are
fed. Through the additional guidance of the upper threads by
the thread take-up levers 12, the thread length between
needle tip and drive roller 6 can be regulated additionally
by vertical adjustment of the thread take-up levers 12, so
that possibly the drive mechanism 10 only needs to be able
to rotate in one direction It is, however, also conceivable
that if the drive roller 11 is rotated in both directions
for thread feed and thread withdrawal, the thread tension in
the upper thread being stitched in each case is also
regulated by means of the vertical positioning of the thread
take-up lever 12.

With both devices according to Figs. 1 and 2, the upper
thread 3 is fed past a sensor 8 whereby through excursion of
the upper thread 3 by means of sensor S the sensor 8 itself
is subjected to pressure from the upper thread 3. The thread
tension in the upper thread 3 can be determined from this
pressure by simple conversion.'
Fig. 3 shows a detailed view of the drive mechanism 10 with
driven roller 11, which is lightly pressed against roller 6.
The roller 6 is looped once or several times by an upper
thread 3, so that the upper thread cannot slip through on
the roller 3. Possibly, the surface of roller 6 is
rubberized, so increased friction is produced between upper
thread 3 and roller 6. The mounting plate for the axle of
the roller 6 is fixed on the stitching head 1 by .r.eans of
the fastening part 15. A guide rail 15, which comprises
several window-like openings 5c ' in the form of eyes, is
positioned as it were on the mounting device 15.
Figs. 4, 5 and 6 show typical tension gradients during a
stitch or loop formation. Fig. 4 in this case shows a
tension gradient, in which both the lower thread ana the
upper thread have a function. The first tension peak in the
angle range of approx. 50° is caused by threading the lower
thread through the loop formed by the upper thread. If the
lower thread has broken, the strength exerted by the lower
thread on the upper thread is reduced, and the first tension
peak, as shown in Fig. 5, turns out to be considerably
smaller. On the other hand, if the upper thread has broken,
then only very slight thread tension is detected by the
sensors (Fig. 6).

Fig. 7 shows a device to measure the thread tension in the
case of a multi-thread stitching or sewing head. The upper
threads 3 are fed via a thread reversing mechanism 16, 17,
whereby the upper thread 3 just stitched exerts forces on
the U-shaped part 16 duer to looping of the parts 16, 17,
whereby the U-shaped part 16 again exerts forces on the
mounting device 19. As shown in Fig. 8, each mounting device
19 consists of two angular brackets 20, 23, which are joined
to one another by means of a screw 22 in each case. Both
free ends of the U-shaped part 16 are attached by means of
such a mounting device 19 to the front la of the stitching
head 1. The ends of the U-shaped part 16 are attached by
means of connecting screws 24 to the one leg of the angular
bracket 23. The other leg of the angular bracket 23 is
connected by means of the connecting screw 22 with the first
leg of the lower angular bracket 20. This leg comprises a
thin-walled area 20a, which is bent by the tension in the
upper thread. The deformation of the angular area 20a is
recorded by means of a sensor S shown in Fig. 9, whereby
conclusions about the thread tension in the upper thread
just stitched are possible. The other leg of the lower
angular bracket 20 is attached to the stitching head 1 by
means of a screw 21. The upper reversing bar 17 is
positioned by means of fastening parts 18 and screws 18a
above the reversing mechanism 16. The reversing mechanism or
the U-shaped part 16 comprises eyes 16, through which an
upper thread is guided in each case.
Fig. 9 shows a sectional view through the reversing
mechanism according to Figs. 7 and 8. In the thin-walled
area 20a, a wire strain gauge as sensor S is bonded onto the
lower surface of the angular bracket 20, which records
excursions or deformation of the leg of the lower angular
bracket 20. The wire strain gauge or sensor S, in order to
prevent damage or contamination, is sealed with as flexible
a material as possible. Advantageously, the supply lines 25
to the sensor S are arranged in such a way that despite
deformation of the angular bracket 20 are onxy exposed to
minor mechanical stress, so that they are not subject to
increased wear and tear.
The dimensions of the mounting device 19, 20, .23 for
attaching the U-shaped part 16 to the stitching head 1
should be such that the small forces F arising, which due to
the thread tension of the upper threads bear on the U-shaped
part lead to sufficiently large deformation of the leg with
the thin-walled area 20a of the angular bracket 20. For this
reason, leverage ratios are to be configured accordingly. It
should be ensured that due to mechanical stress and natural
vibration of the stitching head the intrinsic movements of
the stitching hesd do net lead to vibration of the angular-
bracket 20 and thus to false readings.

WE CLAIM:
1. A device for stitching or a sewing machine comprising :
- a thread driving mechanism (10), having a roller (11) mounted for
rotating about an axis, said roller driven by the drive unit (10) in
both directions about the axis thereof; and
- a feed spool (4) for winding off an upper thread (3) for thread feed
or loop formation, by turning said roller (11) in one direction, and
pulling back the upper thread (3) for thread withdrawal by rotating
the roller in the opposite direction, thus drawing the stitch or loop;
characterized in that a measuring device (8) is provided for measuring the
tension in the upper thread (30) during a stitching or sewing process so
that the thread drive mechanism (10) can be controlled for thread feed
and thread withdrawal depending on the determined thread tension.

2. Device as claimed in claim 1, wherein said thread drive mechanism of the
device is(designed to end thread withdrawal when level of determined thread
tension exceeds a preset threshold value.
3. Device as claimed in claim 2, wherein the device i.e. sewing or stitching
machine is designed to end the current stitch or loop formation if the
threshold value is exceeded.
4. Device as claimed in claim 3, wherein the device i.e. sewing or stitching
machine is Resigned to begin the next stitching or the next loop after
finishing the stitch or loop formation.
5. Device as claimed in any one of the previous claims, wherein the device is
designed to reduce the thread tension by controlling the thread drive
mechanism, when the determined thread tension approaches a tension
threshold value.

6. Device as claimed in any one of the previous claims, wherein the device is
designed to continually compare the determined tension levels during thread
withdrawal with tension levels stored in a data base and check whether the
determined tension gradient lies within the standard range.
7. Device as claimed in any one of claims 1 to 5, wherein the device is
designed ito carry out a plausibility check during thread withdrawal
generally as to whether the measured tension levels lie within the standard
range.
8. Device as claimed in any one of the previous claims, wherein the device is
designed to generally check the tension gradient during or after the stitch or
loop formation as to whether the tension in the thread has not reached
certain tension threshold values at certain times during the stitch or loop
formation, and in that case to detect the lower thread breakage.
9. Device as claimed in any one of the previous claims, wherein the device
is designed to detect the upper thread breakage as soon as the thread
tension no longer changes or only slightly.

10. Device as claimed in any one of the previous claims, wherein the device is
designed to generally check the tension gradient during or after the stitch or
loop formation as to whether the tension in the thread exceeds certain
tension threshold values at certain times during the stitch or loop formation,
and in that case further thread to gradually advance by means of the thread
drive mechanism until a maximum permissible length of thread is reached or
however the thread tension falls again below the tension threshold value.
ll.Device as claimed in claim 10, wherein the device is (designed to
interrupt the stitching or loop formation process if on reaching the
maximum permissible thread length the thread tension is too much.
12.Device as claimed in any one of the previous claims, wherein the device is
designed \to the length of thread supplied for the next stitch or loop
formation calculate depending on at least one of the parameters; thread
structure, thread composition, thread type, as well as kind, length
and situation of the stitch or loop being formed next and to make
available the computed thread length by means of the device.

13. Device as claimed in any one of the previous claims, wherein the device
to record the thread tension of the upper thread current being stitched or
sewn in the case of a stitching or sewing machine with several upper threads
being stitched alternatively after one another comprises a thread reversing
mechanism, which reverses the upper threads at least once, and that the
device has at least one sensor to record the force exerted on the thread
reversing mechanism (16,17) by the upper thread (3) currently being stitched
or sewn.
14. Device as claimed in daiml3, wherein the thread reversing mechanism is
fixed to the stitching head directly or by means of an intermediate part.
15. Device as claimed in claim 13 or 14, wherein the sensor is positioned
between the thread reversing device and the switching head.
16. Device as claimed in any one of claims 13 to 15, wherein the thread
reversing device is a U-part, which is fixed to the stitching head at its two
ends directly or via an intermediate part.
17. Device as claimed in claim 16, wherein at least one reversing point for the
at least one upper thread is arranged between the two ends of the U-part.
18. Device as claimed in claim 16 or 17, wherein excursion of a junction point
from its rest position can be detected or calculated by means of a sensor in
each case.
19. Device as claimed in claim 16 or 17, wherein one force arising at one or
both junction points can be detected or calculated by means of a sensor in
each case.
20. Device as claimed in any one of claims 16 to 19, wherein one eye forms a
reversing point in each case.
21. Device as claimed in any one of the previous claims 16 to 20, wherein
each end of the U-part is arranged on an angular bracket, whereby the
deformation of at least one angular bracket can be recorded and/or
calculated by means of at least one sensor in each case.

22. Device as claimed in claim 21, wherein the angular bracket has a thin-
walled area, whereby control electronics with the at least one sensor
determine the deformation of the area and/or the forces arising within this

23. Device as claimed in any one of the previous claims, wherein control
electronics compute the thread tension of the thread just stitched or sewn
from the deformation or excursion determined in each case.
24. Device as claimed in claim 23, wherein control electronics consider
distance between the reversing point of the thread just stitched or sewn in
the computation of the thread tension.
25. Device as claimed in claim 23 or 24, wherein control electronics averages
the forces occurring at the two fixing points of the thread reversing
mechanism arising the forces or weights these according to the distance of
the reversing point of the thread just stitched or sewn, whereby the thread
tension is calculated based on the averaged or weighted forces or torques.

26. Device as claimed in any one of the previous claims, wherein the sensor
is a pressure sensor or a wire strain gauge.
27. Device as claimed in any one of the previous claims, wherein the sensor
is a piezo element.
28. Device as claimed in claim in any one of the previous claims, wherein a
control system of the sewing or stitching machine regulates the thread drive
mechanism.
29. Device as claimed in any one of the previous claims, wherein a
control system of the sewing or stitching machine regulates the thread drive
mechanism and that the control system of the sewing or stitching machine
determines the tension in the upper thread by means of the measuring
device.

30. Device as claimed in any one of the previous claims, wherein a
control system of the sewing or stitching machine regulates the thread drive
mechanism or that the control system of the sewing or stitching machine
determines the tension in the upper thread by means of the measuring
device.
31. Process for forming at least one stitch or at least one loop using a device
according to one of the previous claims, wherein a pre-determined thread
length is made available with the aid of the device for forming a loop of
the upper thread underneath the stitching foundation, and that next the
lower thread is transported by the shuttle through the formed loop, as a
result of which by transporting the lower thread through the loop the
upper thread is tensioned, and that the tension in the upper thread is
determined by means of the measuring device, whereby if a tension
threshold valuers exceeded gradually more upper thread is advanced with
the aid of the device until a maximum permissible length of upper thread
is reached or however the thread tension falls again below the tension
threshold value.

32. Process as claimed in claim 31, wherein if on reaching the maximum
permissible thread length, the thread tension is still too much, the stitching or
loop formation process is interrupted.
33. Process as claimed in claim 31 or 32, wherein after the lower thread has
been fed through the loop formed by the upper thread, the upper thread is
tightened with the help of the device, until a pre-set, calculated or
predefinable tension threshold value is reached.
34. Process as claimed in any one of claims 31 to 33, wherein the tension of
the upper thread is determined within the time frame, in which the lower
thread has to be fed by means of the shuttle through the loop formed by the
upper thread, whereby breakage of the lower thread is detected, as soon as
the thread tension of the upper thread does not exceed a minimum threshold
value within the time frame.

35. Process as claimed in any one of the claims 30 to 34, wherein breakage
of the upper thread is detected, as soon as the determined tension in the
upper thread does not change during pre-set or pre-definable period or only
slightly.
Dated this 23rd day of October, 2003
B B SEN
L S DAVAR & CO
APPLICANTS' AGENT
The invention relates to a device for a stitching or sewing machine, said device
comprising a thread drive mechanism (10) with a roller (11) mounted to rotate about
an axis, which may be driven by a drive unit in both directions about the axis thereof.
On turning said roller in one direction, an upper thread (3) for thread feed or loop
formation Is wound off a feed spool (4) and by rotating the roller (11) in the opposite
direction, the upper thread is pulled back (thread withdrawal) and thus drawing the
stitch or loop. During the stitching or sewing process a measuring device (8)
measures the tension in the upper thread and the device controls the thread drive
mechanism depending on the determined thread tension.

Documents:

1365-kolnp-2003-granted-abstract.pdf

1365-kolnp-2003-granted-claims.pdf

1365-kolnp-2003-granted-correspondence.pdf

1365-kolnp-2003-granted-description (complete).pdf

1365-kolnp-2003-granted-drawings.pdf

1365-kolnp-2003-granted-examination report.pdf

1365-kolnp-2003-granted-form 1.pdf

1365-kolnp-2003-granted-form 18.pdf

1365-kolnp-2003-granted-form 2.pdf

1365-kolnp-2003-granted-form 26.pdf

1365-kolnp-2003-granted-form 3.pdf

1365-kolnp-2003-granted-form 5.pdf

1365-kolnp-2003-granted-reply to examination report.pdf

1365-kolnp-2003-granted-specification.pdf


Patent Number 223045
Indian Patent Application Number 1365/KOLNP/2003
PG Journal Number 36/2008
Publication Date 05-Sep-2008
Grant Date 03-Sep-2008
Date of Filing 23-Oct-2003
Name of Patentee ZSK STICKMASCHINEN GMBH
Applicant Address MAGDEBURGER STRASSE 38-40, 47800 KREFELD-GARTENSTADT
Inventors:
# Inventor's Name Inventor's Address
1 KIRCH BERND KEMPENER STR. 29, 47839KREFELD
2 OSTHOFF WALTER HOHER WEG 21, 46514 SCHERMBECK
3 STEINKI KARL KNIEBELSTRASSE 3, 47918 TONISVORST
4 BIEGELBAUER WALTER UERDINGER STRASSE 628, 47800 KREFELD
PCT International Classification Number D05C 11/08
PCT International Application Number PCT/EP02/02542
PCT International Filing date 2002-03-08
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 101 30 345.9 2001-06-27 Germany