U.S. patent application number 11/783819 was filed with the patent office on 2007-10-25 for method and device for sewing machine.
This patent application is currently assigned to VSM GROUP AB. Invention is credited to Rolf Wahlstrom.
Application Number | 20070245940 11/783819 |
Document ID | / |
Family ID | 38618246 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070245940 |
Kind Code |
A1 |
Wahlstrom; Rolf |
October 25, 2007 |
Method and device for sewing machine
Abstract
A sewing machine for stitching thread with several colors
according to a sewing pattern stored in the form of stitch data in
a memory, where the thread is dyed by a mechanism for dyeing the
thread and where the upper thread is fed to a needle by a thread
feeder. The thread consumption per stitch is calculated by a
control unit from the data. The thread feeder is controlled by the
control unit so that for each step it advances the calculated
thread consumption for the stitch. A thread consumption for the
quantity of stitches which according to the sewing pattern remains
between the sewing material and the next color change for the upper
thread in the sewing pattern is calculated by the control unit,
whereupon the dyeing mechanism is controlled by the control unit to
initiate the dyeing of the upper thread with the next color at a
time when the calculated thread consumption is equal to the length
corresponding to the length of the actual upper thread remaining
between the sewing material and the dyeing point in the dyeing
mechanism.
Inventors: |
Wahlstrom; Rolf; (Jonkoping,
SE) |
Correspondence
Address: |
VENABLE LLP
P.O. BOX 34385
WASHINGTON
DC
20043-9998
US
|
Assignee: |
VSM GROUP AB
Huskvarna
SE
|
Family ID: |
38618246 |
Appl. No.: |
11/783819 |
Filed: |
April 12, 2007 |
Current U.S.
Class: |
112/270 |
Current CPC
Class: |
D05B 67/00 20130101 |
Class at
Publication: |
112/270 |
International
Class: |
D05B 81/00 20060101
D05B081/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 13, 2006 |
SE |
0600837-9 |
Claims
1. A sewing machine, comprising: a needle fitted with an upper
thread, a drive element which drives the needle to perform an
upward and downward movement to guide the upper thread through a
sewing material which is fed between the upper thread and the under
thread, so that the upper thread forms a loop below the sewing
material, a shuttle which houses an under spool for the under
thread, a gripper arm on the shuttle which hooks into the loop on
the upper thread and guides the upper thread around the under spool
so that a stitch is produced on the sewing material, and a take-up
lever which at each stitch draws a knot which is formed in the
sewing material by the upper thread and under thread in
cooperation, a memory for storing stitch data for a sewing pattern,
a thread feeder to feed upper thread to the needle, a control unit
which from the data calculates the necessary thread consumption per
stitch and thus controls the thread feeder, a function where the
control unit in collaboration with the thread feeder adjusts the
advanced thread quantity in relation to the theoretically
calculated thread consumption, a mechanism for dyeing the upper
thread where a color change for the thread dyeing is controlled by
the control unit to be performed at a time when the calculated
thread consumption in the quantity of stitches which according to
the sewing pattern is present between the sewing material and the
next color change in the sewing pattern, is equal to the length
which corresponds to the length of the actual upper thread
remaining between the sewing material and a dyeing point in the
dyeing mechanism.
2. The sewing machine according to claim 1, wherein the stitching
data comprises types of stitch, parameters for the stitch and the
stitch color, whereby the control unit reads a stitch color from
the stitch data.
3. The sewing machine according to claim 2, wherein the dyeing
mechanism comprises dye cartridges for at least the dye components
yellow, magenta and cyan.
4. The sewing machine according to claim 3, wherein the dyeing
mechanism furthermore comprises a dye cartridge for a black dye
component.
5. The sewing machine according to claim 3, wherein the thread
feeder comprises a drive unit which feeds the upper thread in
steps.
6. The sewing machine according to claim 5, wherein for each step
during which the thread feeder advances the upper thread, a
quantity calculated by the control unit of the respective dye
component is applied to the upper thread by means of a dye
cartridge associated with the dye component.
7. The sewing machine according to claim 6, wherein for each step
during which the thread feeder advances the upper thread, a
quantity calculated by the control unit of the black dye component
is applied to the upper thread by means of a dye cartridge with
black dye.
8. The sewing machine according to claim 1, wherein the function
for adjusting thread quantity is implemented as a program in the
control unit.
9. The sewing machine according to claim 1, wherein the sewing
machine is fitted with a cutter device which is controlled by the
control unit to draw down a pre-determined length of the upper
thread under the sewing material and there perform a thread cut,
wherein the length of upper thread drawn down contains the color
change point.
10. A method for dyeing upper thread with a sewing machine which
comprises: a needle fitted with an upper thread, a drive element
which drives the needle to perform an upward and downward movement
to guide the upper thread through a sewing material which is fed
between the upper thread and the under thread, so that the upper
thread forms a loop below the sewing material, a shuttle which
houses an under spool for the under thread, a gripper arm on the
shuttle which hooks into the loop on the upper thread and guides
the upper thread around the under spool so that a stitch is
produced on the sewing material, and a take-up lever which at each
stitch draws a knot which is formed in the sewing material by the
upper thread and under thread in cooperation, a memory for storing
stitch data for a sewing pattern, and a mechanism for dyeing the
upper thread, the method comprising: feeding the upper thread to
the needle with a thread feeder, calculating a necessary thread
consumption per stitch with a control unit from said data, the
thread feeder is controlled by the control unit so that for each
stitch it advances the calculated thread consumption for the
stitch, a thread consumption for the quantity of stitches which
according to the sewing pattern remains between the sewing material
and the next color change for the upper thread in the sewing
pattern is calculated by the control unit, the advanced thread
quantity in relation to the theoretically calculated thread
consumption is adjusted by the control unit in collaboration with
the thread feeder, the dyeing mechanism is controlled by the
control unit to initiate a dyeing of the upper thread with the next
color at a time when the calculated thread consumption is equal to
length corresponding to the length of the actual upper thread
remaining between the sewing material and the dyeing point in the
dyeing mechanism.
11. The method according to claim 10, wherein the color of a stitch
is read from stitch data comprising data for the type of stitch,
parameters for the stitch and the stitch color.
12. The method according to claim 11, wherein the dye cartridges
apply at least any one of the dye components yellow, magenta, cyan
and black to the upper thread.
13. The method according to claim 12, wherein the dye component
concerned is applied at a time which is compensated for a
difference between the said length A and length which corresponds
to the length of the actual upper thread remaining between the
sewing material and the dye cartridge corresponding to the dye
component concerned in the dyeing mechanism.
14. The method according to claim 13, wherein the upper thread is
advanced in steps by means of a drive unit in the thread
feeder.
15. The method according to claim 14, wherein for each step during
which the thread feeder advances the upper thread, a quantity
calculated by the control unit of the respective dye component is
applied to the upper thread by means of a dye cartridge associated
with the dye component and thus a color change point is produced
from which the upper thread is changed in color to the next color
for the upper thread in the sewing pattern.
16. The method according to claim 10, further comprising: that when
the thread consumption per stitch is corrected by the thread feeder
by deviation from the data according to the sewing pattern, and a
color change point at the same time is located along length A, the
control unit is programmed to compensate for this by, for a
specific time, feeding a greater or lesser quantity of thread per
stitch than that calculated according to the sewing pattern.
17. The method according to claim 16, further comprising that
compensation is performed in that: when the correction is made by
advancing extra thread quantity, the thread quantity per stitch is
reduced in relation to that previously calculated until the
calculated thread quantity and actually fed thread quantity
correspond again, or when the correction is made by advancing less
thread quantity, the thread quantity per stitch is increased in
relation to that previously calculated until the calculated thread
quantity and actually fed thread quantity correspond again.
18. The method according to claim 10, further comprising: the
control unit records that in the sewing material, a thread length
with a first color of upper thread has a large number of stitches
with only small direction changes, the control unit automatically
adds a pre-determined length to the calculated thread consumption
for the thread length with the first color, a corresponding
extension of the calculated thread consumption for the subsequent
thread length with a second color is performed by the control unit,
a certain length of the upper thread around a color change point
which is constituted by the border between the first and the second
color on the upper thread is drawn down on stitching below the
sewing material and at least a part of the upper thread drawn down
is cut.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Swedish patent
application number 0600837-9 filed 13 Apr. 2006.
TECHNICAL FIELD
[0002] The present invention concerns a device and a method for
dyeing thread on a sewing machine. In particular the invention
concerns a method and a device for dyeing the upper thread on a
sewing machine by means of a dyeing mechanism controlled by a
control unit which calculates the time for colour change according
to a pre-determined sewing pattern.
STATE OF THE ART
[0003] Sewing machines of the lockstitch type have been known
within the art for some time and their working method is well
known. If for the sake of simplicity a machine with a single needle
is taken as an example, the stitch in this machine is formed by an
upper thread and an under thread being linked together by means of
a needle which moves forward and back through a sewing material
passing over a sewing table that normally lies in a plane
substantially perpendicular to the length of the needle. On most
conventional sewing machines of this type, the upper thread is
drawn from a bobbin which stores the upper thread, via a thread
take-up lever which through a movement oscillating to and from the
sewing material provides the needle with the upper thread. The term
"upper" in the description below refers to the side of the sewing
material where the needle is accommodated. "Under" refers to the
side on the sewing material where the knot is formed. Furthermore
in the text where the term "thread" is used, this is synonymous
with "upper thread" unless specified otherwise.
[0004] When the take-up lever is in its top position the maximum
quantity of thread has been drawn out before the next stitch,
whereupon the take-up lever turns down again in its movement. After
the turn of the take-up lever, below the sewing material a loop of
thread is formed as the drawn out thread is not immediately fully
drawn back by the take-up lever.
[0005] The under thread is unwound from a spool which is housed in
a shuttle below the sewing material. The shuttle can be of the
rotating type and is fitted with a gripper arm (also called the
hook point) which on the rotating movement of the shuttle hooks
into the loop formed by the upper thread and on its continuing
movement guides the upper thread around the shuttle.
[0006] When the take-up lever in its oscillating movement is again
moved upwards from the sewing material, the take-up lever draws
back the surplus quantity of upper thread i.e. the quantity which
was not used in the current stitch. The pulled out thread which
forms said loop is tightened again whereupon a locking stitch is
formed by the upper thread and under thread in collaboration, as
the gripper has pulled the upper thread around the under thread.
Another device on the sewing machine now advances the fabric for
the next stitch.
[0007] Said oscillating movements performed by the needle, take-up
lever and gripper are synchronised with each other and repeated
cyclically for each stitch performed on the sewing machine.
[0008] On use of a sewing machine in particular for embroidery, it
is necessary to ensure that there are sufficient threads of
different colours as required for the proposed sewing operation and
to use these colours selectively. If an operator for a sewing
machine intends to sew a complicated embroidery following a
pattern, the stitching in this may require many different colours
of the upper thread. The operator is thus forced to break off the
sewing to change the upper thread each time a new colour is
required in the upper thread according to the pattern. Such an
operation, i.e. changing the upper thread, involves the steps:
stopping the sewing machine, lifting the presser foot which holds
the material, cutting off the upper thread previously used,
removing the upper thread, acquiring a new upper thread with the
desired colour. The new upper thread is threaded through a number
of guides, such as a thread tensioner, the take-up lever and the
eye of the needle, all of which measures together are difficult,
labour-intensive and time-consuming. Alternatively more complicated
technology is used with several needles and take-up levers, one for
each colour.
[0009] To eliminate these disadvantages it has been proposed that a
sewing machine is fitted with a dyeing mechanism through which an
undyed or white upper thread is selectively dyed with a given
colour in synchrony with the stitching according to the pattern
stitched with the sewing machine. In this case however a time delay
occurs between the time when the upper thread is dyed in the dyeing
mechanism and the time when the upper thread with the dyed colour
reaches the needle to form a new stitch with the new colour in the
sewing material. Thus when the sewing pattern requires a change in
colour for the upper thread, there is already a piece of upper
thread between the dyeing mechanism and the needle, which is dyed
with the last colour used. This piece of upper thread cannot be
used in the next sequence in stitching according to the
pattern.
[0010] To eliminate this problem a solution is proposed for example
according to document U.S. Pat. No. 4,538,535. According to the
description in this document the difficulty with the remaining
thread located between the sewing material and dyeing mechanism, on
a change of colour on the upper thread, is solved by a device which
draws off the intermediate dyed thread according to the last colour
requirement, whereafter the extended intermediate part is cut away
by a cutter. The sewing machine can then continue stitching with
the new dyed upper thread remaining after cutting. The cut
intervening part is removed by blowing. Relatively long sections
(of the order of 40 cm) of thread must be cut away and disposed of
on each colour change. These can then tangle during handling.
[0011] Document U.S. Pat. No. 6,189,989 which gives a general
description of the art of thread dyeing specifies a further
solution to said difficulty. According to the description in this
document there is a detector, e.g. a measuring roller, which reads
the quantity of thread transferred from a thread store. By
compiling data from a sewing pattern for the current stitching,
data corrections depending on stitch type and sewing material and
the thread usage detected, a time of colour change is established
at the dyeing mechanism by a control unit. As the upper thread in
conventional sewing machines is drawn out by the take-up lever and
the thread is also advanced for a very small part of the time for a
stitch, the upper thread feed speed varies greatly during the
stitching. The thread length per stitch also has a certain random
variation. There is therefore a great risk that the dyed thread
will reach the sewing material with the colour change point too
early or too late in relation to the requirements of the sewing
pattern. In the patent cited, this can be corrected by means of
temporary stitching with a number of stitches performed on the
sewing material so that the upper thread is used for the surplus
stitches, so that it can be predicted with certainty that the
intended colour will be present at the upper thread according to a
program which controls the sewing according to the pattern. Such
temporary stitches can then e.g. be oversewn, which is not
particularly advantageous as the colour of the underlying stitch in
the end product can show through covering stitches.
[0012] As shown it is very important when dyeing the upper thread
used on sewing according to a sewing pattern, such as an
embroidery, that a computer program in a control unit for the
sewing machine controlling the dyeing can be supplied with data for
the thread movement. This is required partly so that the program
can meter out the correct colour quantity and partly to coordinate
the start time for colour change on the upper thread with the time
at which the upper thread with different colour should reach the
sewing material, according to the sewing pattern stored in a memory
connected to the control unit.
[0013] Attempts have been made to solve the problem as described by
means of a buffer store for the upper thread between the dyeing
point and the sewing material. This makes it more difficult to keep
track of the thread quantity which remains in between. Another
difficulty is to supply the program with information on how much
thread will be drawn out before the upper thread with the new
colour will be used due to e.g. the number of stitches remaining,
the stitch length, fabric thickness, fabric quality, sewing
direction and direction changes.
[0014] One object of the present invention is to find a solution to
the difficulties reported above.
DESCRIPTION OF THE INVENTION
[0015] According to one aspect of the invention a device is
presented.
[0016] A further aspect of the invention is a method.
[0017] According to the invention a sewing machine is provided
which feeds the needle with upper thread through a thread feeder
which portions the upper thread to the sewing according to a
stitching pattern. The stitching pattern e.g. embroidery is entered
and stored in a memory which can be read by a control unit
constituted by the processor of the sewing machine. The processor
then performs the sewing following the sewing pattern by
controlling the active elements of the sewing machine.
[0018] The thread feeder is supplied according to data for the
sewing pattern entered from the processor, which controls the
portioning of the upper thread for each individual stitch. This
method of handling the upper thread gives better potential for a
correct and reliable control of the dyeing process for the upper
thread than with feeding of the thread only by means of the take-up
lever and conventional washers for friction braking of the upper
thread, because of the great speed variation of the thread. As the
sewing pattern is accessible to the processor of the sewing
machine, a possibility is created for calculating the thread usage
from a current position for the needle on the sewing material up to
a stitch in the pattern where the thread colour must be changed.
The dyeing mechanism according to the invention is located between
the thread store and the thread feeder. The thread feeder in
addition feeds the upper thread reasonably evenly distributed over
time and keeps the thread tensioned between itself and the thread
store, which means that the amount of upper thread between the
thread feeder and the dyeing point is well known. The length of the
upper thread between the thread feeder and the sewing material is
machine-specific and therefore also well known, where the total
length of upper thread A between the dyeing point and the sewing
point on the sewing material is known and can be stored in the
sewing machine processor. For simplicity's sake length A is called
the dyed length.
[0019] On difficult conditions e.g. when the pattern contains a
small number of stitches with severe direction changes e.g.
straight seams and very short stitches that are sewn at high speed,
despite the refined technique according to the invention it may be
difficult to achieve the colour change on the upper thread at
precisely the right stitch in the sewing. To cover this variant of
sewing problem too, the sewing machine additionally can be fitted
with a cutting device where the upper thread is drawn down below
the fabric and cut off so that the two ends of the thread, in an
interval around the assumed calculated colour change point, remain
on the underside of the sewing material.
[0020] The advantages according to the invention are a smoother
thread movement and hence there is no need e.g. to resort to any
buffer thread store nor for safety reasons to sew any temporary
stitches on the fabric with thread around the colour change point
on the upper thread. A further advantage is that it is possible,
under difficult sewing conditions, by a relatively reliable
calculation of the thread usage, to draw down the thread and
perform a cut so that a very small part of the upper thread is
unnecessarily consumed, and thus ensure a correct thread colour in
every stitch performed according to the sewing pattern. A further
advantage on use of dyeing at the sewing machine with the support
of a thread feeder is that the thread usage can be controlled to a
certain extent, as will be described in more detail below.
[0021] The thread feeder can comprise a thread portioner of the
type described below. Any device which portions out upper thread
can however be used in the invention. For example a motor is
possible, e.g. a stepper motor which drives the roller between
which the thread is clamped and advanced. Another variant can
comprise magnets which cyclically clamp the upper thread between
two plates that are driven by the magnets so as to repeatedly move
the plates in the longitudinal direction of the thread between
clamping.
[0022] The thread feeder as above can comprise the thread feeder
described e.g. in US 2005/0223958 A1, the content of which is
hereby incorporated as a whole in this description.
[0023] The control unit of the sewing machine receives information
on parameters entered by the sewing machine operator and data for
the current position of mechanical elements relevant for the
correct performance of a selected stitch, and controls the
stitching of the sewing machine on the basis of these parameters
and the current position. Such control is known and do not belong
to the invention so it is not reported here.
[0024] The control unit controls the drive element, e.g. said
motor, for the thread feeder, wherein the drive element is used to
effect the setting for the consumption of upper thread per stitch
calculated in the processor.
[0025] Further refinements of the present invention are shown in
the detailed description below which should be interpreted in
conjunction with the enclosed drawings. The drawings are given
purely for illustrative purposes and do not restrict the invention.
The drawings are not to scale and show only conceptual structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 shows a diagrammatic sketch with a front view of a
sewing machine with thread feeder and dyeing mechanism for the
upper thread.
[0027] FIG. 2 shows a diagrammatic sketch from the side of a sewing
machine according to FIG. 1 showing the upper and lower positions
of the thread take-up lever, via which the stroke length is
illustrated, and where furthermore the shuttle with gripper arm and
thread loop are depicted below the sewing table.
[0028] FIG. 3 shows diagrammatically a thread feeder which feeds
the upper thread through rollers that are driven by a motor which
in turn is controlled by a processor.
[0029] FIG. 4 shows in perspective an example of drive of the upper
thread through the said rollers.
[0030] FIG. 5 shows various alternatives for positioning of the
knot for a straight seam in relation to the thickness of the
fabric.
[0031] FIG. 6 shows various alternatives for positioning of the
knot on a zigzag seam in relation to the height of the knot in the
fabric.
[0032] FIG. 7 shows a comparison between different positions of the
knot in relation to the fabric on a zigzag seam.
[0033] FIG. 8 shows a comparison between different positions of the
knot in relation to the fabric on a zigzag seam where the stitch is
viewed from the underside.
[0034] FIG. 9 shows a simplified block diagram of essential
elements in the sewing machine concerned by the present
invention.
[0035] FIG. 10 shows a flow diagram with the sequence of events on
thread dyeing according to an example embodiment of the
invention.
[0036] FIG. 11 shows a tight zigzag seam with a colour change
performed where a cut has been used. The upper picture shows the
underside, where it is evident that the colour change does not
perfectly correlate with the point where the cut was performed.
DESCRIPTION OF THE METHOD
[0037] To implement the invention, a number of embodiments will be
described below based on the enclosed drawings.
[0038] FIG. 1 shows symbolically a sewing machine 1 where in the
known manner a sewing material 2 (in the description below, the
sewing material 2 is referred to as a fabric) is fed between an
under thread 3 and an upper thread 4 to produce a seam which is
constructed of the desired stitches by means of a needle 5 which is
periodically passed through the fabric 2. The fabric 2 in the
example is guided over a sewing table 6 which also holds a spool 7
for the under thread 3 encapsulated in a shuttle 8. The upper
thread 4 is guided through a take-up lever 9 which through an up
and down cyclic movement creates a loop 10 in the upper thread 4
when the needle 5, through the eye of which the upper thread runs,
carries the upper thread through the fabric 2, and the take-up
lever 9 turns back up from its lowest position. A gripper arm 11
hooks into the loop 10 when the shuttle 8 rotates. To produce a
stitch, in this case a lockstitch, the needle 5 is moved in an up
and down movement so that the needle 5 carries the upper thread 4
down through the fabric 2, whereupon the shuttle 8 guides the upper
thread 4 around the spool 7 which houses the under thread 3,
creating a knot in the fabric 2 when the needle 5 has passed back
up through the fabric and the take-up lever 9 has tightened the
knot in the stitch.
[0039] The upper thread 4 is fed via a thread feeder 13 which
distributes the thread to the take-up lever 9 via a thread feed
spring 14.
[0040] The machine includes a control program which e.g. is stored
in a processor C. The control program receives information on the
position of the take-up lever 9 and the needle 5 in the cyclic
stitching process. It is known within the art to pre-determine the
consumption of thread per stitch by calculating stitching
parameters for the stitch currently used in a particular seam. Such
a calculated and hence pre-determined thread consumption per stitch
is performed in the processor of the sewing machine according to
the invention and constitutes the basis for the feed by a motor M
(see FIG. 3) which implements the thread feed.
[0041] FIG. 3 shows diagrammatically a thread feeder 13 controlled
via processor C. Input data in the form of control parameters to
the processor C in the figure are shown in the illustration as an
arrow which points in to the processor. The processor C is
furthermore designed to control a stepper motor M which is
mechanically coupled to three drive rollers R1, R2, R3 via a gear
mechanism marked in the figure as 20. Here we describe one
embodiment where the motor M is constituted by a stepper motor but
other types of drive element controlled in other ways than through
stepping can be used if applicable. The upper thread 4 is guided
between the rollers R1, R2, R3, whereupon the stepping of the motor
M means that the upper thread 4 is fed forward to the needle 5. The
quantity of thread advanced is determined by the number of steps by
which the motor moves. The upper thread 4 is advanced when the
motor steps in the forward direction marked F. The feed is intended
to be controlled depending on the type of stitch, thread thickness,
fabric etc. The number of steps by which the motor is driven
forward during a stitch is mainly controlled by the calculated
value for the feed of thread required.
[0042] FIG. 1 shows a dyeing mechanism 15 for dyeing the upper
thread 4 with the desired colour. The dyeing mechanism 15 dyes the
thread in synchrony with the movement of the thread. Suitable
elements for dyeing can be an ink jet cartridge or spray unit which
applies one or more dye components to the thread. These dye
components are suitably yellow, magenta, cyan and black. By varying
the quantity of said individual dye components, the desired colour
of the upper thread 4 can be achieved. After the thread has been
dyed, it passes through a drying station 16 where the dye is dried
and hardened e.g. with hot air. Dyeing devices of different types
are used within the art. One example of such a dyeing device is
shown e.g. in specification U.S. Pat. No. 6,189,989 cited above. In
the description below the term dyer is used, which stands for the
dyeing mechanism 15.
[0043] The function for the dyeing process is described in
conjunction with the figures below. A thread store 17 exemplified
by a thread bobbin in FIG. 1 provides the upper thread 4 for
sewing. The upper thread is guided to the dyer 15 after first
passing through a thread brake 18 which gives the upper thread a
thread tension of the order corresponding to 5 grammes. The thread
tension is required to hold the thread taut during dyeing in the
dyer 15.
[0044] The upper thread 4 in the dyer passes one or more dye
cartridges Ye, Ma, Cy, Bl (see FIG. 9) which spray or spread dye on
the upper thread according to the colour data in the stitching
pattern loaded in the memory. The dye cartridges contain dye for
the said dye components. The upper thread is pulled by the thread
feeder 13 through the said devices, from the thread store 17,
through the thread brake 18, dyer 15 and drying station 16 where
the thread feeder 13 for each stitch pulls (or feeds) the thread
quantity used in the stitch concerned. FIG. 9 shows that the thread
passes the dye cartridges in the order Bl, Cy, Ma, Ye. In the
description given Bl corresponds to dye cartridge 1, Cy dye
cartridge 2, Ma dye cartridge 3 and finally Ye dye cartridge 4.
[0045] The processor C controls both the thread feeder 13 and the
dyer 15 so the upper thread receives the right quantity of the dye
component concerned per length unit. The thread feeder 13 comprises
in this example a thread portioner i.e. a device which portions the
thread. The thread portioner 13 is driven, as cited in the example,
by a stepper motor where a thread length r per step performed by
the motor is given. As an example a thread portioner can be
considered which advances the thread length r=0.4 mm per stepper
motor step. From colour data according to the sewing pattern,
information is obtained on the quantity of dye of a particular
colour which is to be applied per length unit of the thread e.g.
per mm thread. In the processor this can be converted to the
quantity of the respective dye component which is to be applied per
motor step of the thread. For each motor step of the stepper motor,
the respective dye cartridge Ye, Ma, Cy, Bl in the dyer 15 applies
the quantity of the respective dye component calculated from the
sewing pattern (and hence according to the control unit) and which
is required to achieve the definitive colour of the thread 4 after
passing the dye cartridges in the dyer 15 (the quantity of dye
calculated for a particular dye component can naturally also be
nil). Thus the control unit can order the application of different
quantities of the dye component concerned to the thread 4 for each
motor step for a correct colour to be achieved on the definitively
dyed thread. The processor in the control unit can e.g. calculate
how many drops of dye should be sprayed by a dye cartridge for a
particular dye component on the thread 4 per motor step. If the dye
cartridges for different dye components are not placed at the same
point along the thread 4, this fact must also be compensated by
calculating the quantity of a dye component to be sprayed onto the
thread and at which time this should be done. According to one
example this can be achieved by the thread length between the
dyeing point and the sewing material A (dye length) for different
dye components being stored in particular in the control unit, by a
respective dye component having a specific dyed length A, where
this dyed length is then named yellow A.sub.y, magenta A.sub.m,
cyan A.sub.c, black A.sub.b. The control unit thus performs a
specific calculation of the quantity and time of the dye component
depending on the dyed length A.sub.y, A.sub.m, A.sub.c, A.sub.b
which applies to the sewing machine and the type of dyer 15
used.
[0046] On use of conventional thread tensioning washers with
friction braking of the upper thread, the problem arises that the
thread in this case is drawn out for a very small part of the time
which elapses per stitch. The result is a very high top speed and
acceleration of the thread 4, which causes great difficulty in
controlling the dye quantity in synchrony with the thread advance.
It is not specified precisely how much thread is drawn out in the
stitch. Instead according to the invention by the use of the thread
feeder 15 a more even, slower and more reliable advance of the
upper thread 4 is achieved.
[0047] When sewing with the thread portioner, in the sewing machine
control unit the thread consumption is calculated for each new
stitch as a function amongst others of the stitch length, fabric
thickness, seam direction and also where in the thickness of the
sewing material the knot is designed to be placed. The stitch
length is taken from stitch data in the sewing pattern. The
thickness of the fabric is measured using the presser foot. If the
sewing machine 1 is fitted with a so-called presser foot servo
according to the prior art, this is used to provide information on
the thickness of the fabric. Otherwise the thickness can be
measured by means of a potentiometer coupled to a rod for the
presser foot which gives a signal according to the height of the
presser foot above the sewing table 6, where the said height
constitutes a measure of the thickness of the sewing material. The
seam direction and change in seam direction also affect the
position of the knot in relation to the fabric 2. The knot location
for a normal seam is in the centre of the fabric, which is
illustrated on the straight seam R1 in FIG. 5 and the zigzag seam
Z1 in FIG. 6. On embroidery, for example, it is desirable for the
knot to remain on the underside of the fabric as shown for straight
seam R2 in FIG. 5 and zigzag seam Z2 in FIG. 6. The reason for this
is to avoid the risk of the under thread being visible from the top
of the embroidery.
[0048] On thread dyeing according to the invention, the thread
consumption for the entire sewing pattern can be calculated from
the stitch data for the pattern. This is not necessary but
according to the invention the thread consumption must be
calculated so far in advance that the thread consumption in the
sewing pattern corresponding at least to the dyed length A is known
(or if required all lengths A.sub.y, A.sub.m, A.sub.c, A.sub.b as
above). As stated, whenever the thread length used according to the
pattern from a current stitch up to a colour change of the thread
is equal to length A, the control program in the control unit
orders a colour change on the thread and hence controls the
cartridges for the dye components in order to create the colour
which is current according to the stitching data for the new
colour. When therefore the thread 4 which is after the length A in
the sewing machine has been used, the sewing according to the
pattern has progressed precisely to the point that it is ready for
a stitch to be sewn with the thread dyed with the new colour after
the colour change.
[0049] The thread portioner 13 also has the function of adjusting
the advanced thread quantity if for some reason a situation occurs
where the theoretically calculated thread quantity is not correct
for a stitch. This can e.g. occur on embroidery where the upper
thread 4 is drawn down below the fabric on severe changes in stitch
direction such as e.g. on a seam as shown for example in a) in
FIGS. 7 and 8. Such a correction of the thread usage in a stitch is
described in the published specification US 2005/0223958 A1, the
text of which as a whole is hereby incorporated in the present
description. If on such a correction of the thread usage for one or
more stitches in relation to the thread usage calculated by the
sewing machine control unit, there is a colour change point on the
upper thread 4 along length A i.e. along the part of the upper
thread 4 which is between the dyer 15 and the fabric 2, the thread
colour and stitch will not correspond to the pattern when the
colour change point should reach the fabric 2 according to the
control system based on the sewing pattern.
[0050] To achieve the object described in the preceding section,
the control unit is programmed to compensate for the corrections
made by the thread usage performed when a colour change point is
located along length A.
[0051] To correct the thread consumption when the thread feeder has
advanced more thread for one or more stitches (as shown for example
in b) in FIGS. 7 and 8) than that calculated based on the sewing
pattern, the thread quantity is continuously reduced for the said
stitches as long as required. Conversely, if correction is
performed when the thread feeder 13 has advanced less thread for
one or more stitches (as shown in example c) in FIGS. 7 and 8) than
calculated based on the sewing pattern, the thread quantity is
continuously increased for these stitches as long as required. The
calculations for this purpose are performed in the control
unit.
[0052] On corrections of thread usage performed by the control unit
in addition to the calculations according to the sewing pattern, if
a colour change has not been carried out along the length A,
instead the control unit is given data for these corrections
performed to compensate for these corrections when determining the
time of the future colour change. This means that the control is
updated with corrections performed according to the description in
the previous paragraph so that the remaining length of thread 4
with the colour currently being sewn by the machine is adjusted
accordingly after the next colour change.
[0053] In certain situations e.g. if an embroidery or seam contains
a large number of stitches with only small direction changes per
stitch, it may be difficult to compensate for thread usage in the
manner just described if it has been found that theoretical
calculation of thread usage is not correct for a seam with a first
colour. When such difficulties occur these are detected by the
control unit. Detection is performed so that the control unit is
programmed to recognise the type of seam which caused the said
difficulties. On detection of such a difficult seam, the control
unit provides a small quantity of extra thread (G/2), in this case
25 mm, for the first colour and the same amount for the second
colour (25 mm) at the next change of colour at the dyer 15. When
according to this sewing pattern the seam with the first colour is
fully sewn, the upper thread 4, in this case and according to this
embodiment, is drawn down by a device which hooks into the upper
thread and draws this below the fabric where the upper thread is
cut away. Here a thread quantity of approx 50 mm is used, whereby
the downward drawn thread contains the colour change point. The
said thread cutting constitutes known technology so the arrangement
for thread cutting is not reported here. In the present invention
where thread cutting is used in conjunction with a thread feeder 13
however, the control unit controls the thread feeder to feed the
thread quantity required for cutting. By means of the method
described it is ensured that the colour change is performed for the
particular stitch at the seam even under the most difficult sewing
conditions. The extra 25 mm given for the respective thread length
or colour can, where applicable, be selected with a different
value. The addition can also be machine-dependent.
[0054] The arrangement and method according to the invention are
illustrated further with reference to a block diagram (FIG. 9) of
the most important components of the sewing machine and by means of
a flow diagram (FIG. 10) of the sequence of events when using
thread dyeing.
[0055] The block diagram according to FIG. 9 shows in the centre of
the figure the processor C of the sewing machine that controls the
elements involved in the process for stitching and dyeing described
in the text above. The processor C according to the example can
constitute the control unit cited in the description. The fabric is
stretched in a so-called embroidery frame symbolised in the figure
by an X-Y unit. The embroidery frame is controlled to move the
fabric in two coordinates, an x-direction and a y-direction. The
drive is supplied by an X-motor for the x-direction and a Y-motor
for the y-direction. Both motors are controlled by processor C
following a sewing pattern. In the example the sewing pattern takes
the form of data for the stitching in the embroidery read into a
memory 20. Data for the stitching in the pattern can be separated
and arranged in a separate data file in a stitch memory 21.
Correspondingly data for the colours for the stitch concerned in
the sewing pattern can be stored in a separate data file in a
colour memory 22. Stitch data or colour data for the pattern
currently in use is fed to the processor C to control the other
elements in the process.
[0056] The processor C in the known manner also controls a main
motor 23 in the sewing machine 1. For the operator's control of the
main motor, a foot control 24 is arranged and connected to the
processor C. In addition to the thread feeder 13, the drying
station 16, thread brake 18 and thread store 17 described above,
the dyer 15 is shown which is illustrated here as containing the
dye cartridges Ye, Ma, Cy, Bl. The upper thread 4 passes through
the dye spraying area of these cartridges. The dyeing point here is
depicted with point P i.e. the point where the colour change of the
upper thread is initiated, which point P in the example coincides
with the dye application point on the upper thread for the first
dye cartridge of the dye component. The figure also shows a thread
feed spring 14 used to determine the time when the knot is made in
a stitch. This information is sent to the processor whereupon the
processor can initiate the advance of the thread for the next
stitch. The take-up lever 9 has been shown symbolically.
[0057] A list of parameters used in the description, claims and
figures is given below: [0058] A Thread length from dyeing nozzle
no. 1 (at dyeing point P) to stitching point. [0059] G Addition to
thread length when using cut to achieve precision at the colour
change. [0060] L.sub.n Thread length for stitch number n at the
sewing point. [0061] S Remaining length of thread for the current
stitch. At the start and cutting, A or G is seen respectively as a
long stitch. [0062] i Counter for colour number at dyeing point P.
[0063] j Counter for colour number at sewing point. [0064] k
Counter for stitch number at sewing point. [0065] t A counter used
to stop the machine after a few stitches after starting with a
newly threaded machine so the user can cut away the starting ends.
[0066] B.sub.n Thread consumption for colour number n. [0067]
F.sub.n Addition to thread consumption for colour number n. F.sub.n
is equal to half G and is added to both B.sub.n and B.sub.n+1.
[0068] r Thread length fed from the thread portioner for each motor
step. [0069] E.sub.n Distance from the first nozzle (in dye
cartridge 1) to nozzle number n (in dye cartridge no. n) for the
different dye components black, cyan, magenta, yellow, where in the
example the dye cartridges (Bl, Cy, Ma, Ye) in the said order are
given numbers 1 to 4. [0070] D The length of thread advanced after
a colour change point on the thread has passed the first nozzle.
[0071] P Dyeing point.
[0072] An example of an embodiment and order of priority for the
various measures which lead to dyeing of the upper thread on a
sewing machine according to one aspect of the invention is listed
below based on the enclosed flow diagram according to FIG. 10. The
flow diagram shows the respective steps taken with reference
numbers from 30. [0073] 30. Start of a new embroidery or
re-threading of a sewing machine. [0074] 31. Residual length S is
set equal to A and all counters are set to 1. F.sub.0 and D are
zeroed. [0075] 32. The user is reminded to keep the thread taut in
order to avoid unusable thread between the dyer and the sewing
point. [0076] 33. An algorithm used in processor C calculates, from
stitch data, data for the feed by the thread portioner 13 which is
used to calculate thread consumption B1 for colour no. i. [0077]
34. Here the user has the opportunity to order a cut at all colour
changes. If "yes", an addition F.sub.i is given to colour no. i
according to step 35. F.sub.i is equal to half G and is added to
both B.sub.i and B.sub.i+1. [0078] 35. F.sub.i is set equal to half
the selected length G. [0079] 36. If in a seam with difficult
conditions for example as described in paragraph [42], a cut is
ordered, according to the program in the same way as by jump from
step 34 to step 35. [0080] 37. The addition of thread length is set
equal to 0, which is normal i.e. no cutting is performed. [0081]
38. An addition is made to remaining thread consumption B1 with the
current value of F.sub.i+F.sub.i-1. This means that a thread
quantity consumed on cutting is divided over the colour ahead of
the cut and the colour behind the cut. [0082] 39. Is the remaining
length S for the current stitch equal to 0? If so proceed at step
40. [0083] 40. Stitch counter for colour i t is increased with 1.
[0084] 41. If the number of stitches sewn is set equal to 6, exit
normal sequence; here the machine stops. [0085] 42. The user can
cut away the excess thread, after which he returns to the main
program at 43. [0086] 43. Condition for whether the current stitch
is the last before colour j is tested. If so, proceed at step 44.
If not, continue the programme at step 46. [0087] 44. Counter for j
is increased with 1. [0088] 45. Check whether the addition for
thread length Fj is equal to zero. If so, proceed with program in
step 46. [0089] 46. The counter for k is incremented by 1. The
remaining length S is equal to the stitch length for stitch k.
[0090] 47. If the thread feeder 13, because of the risk of
incorrect positioning of the knot in a seam, has been ordered to
correct the thread consumption in one or more steps, the program
proceeds with step 48. [0091] 48. Check whether the remaining
thread consumption B1 for the current colour is less than or equal
to length A. [0092] 49. If the answer is "yes" in step 48, the
remaining length S is adjusted during a number of stitches until
the remaining thread consumption B1 again corresponds to the
calculation. [0093] 50. If the answer is "no" in step 48, B1 is
corrected depending on the total corrections according to step 47.
[0094] 51. If the answer to the check in step 45 is no, the
remaining length S is set equal to the thread addition G. [0095]
52. A cut of the upper thread is initiated. [0096] 53. Await start
signal for thread feed. [0097] 54. Thread feed motor runs one step
according to the step table in the processor. Apply dye at all dye
cartridges according to dye data during running with the stepper
motor. D is increased by length r for a stepper motor step. S is
reduced by r and the remaining thread consumption B1 for the
current colour is reduced by r. For each step which the thread
feeder 13 advances, dye is sprayed onto the thread. The number of
dye drops or equivalent of the respective dye component is obtained
from the dye data. [0098] 55. Here it is checked whether length D,
i.e. the length for which the thread fed after a point for colour
change on the thread has passed the nozzle in the first dye
cartridge in the dyer 15, is equal to E.sub.1 which is the distance
between the first and second nozzles. As the colour change point
passes the nozzle concerned, according to steps 55, 57, 59, dye
data is changed for the nozzle concerned to the specified number of
drops of dye (or equivalent) according to the next colour on the
thread in steps 56, 58, 60. [0099] 56. If D=E.sub.1, dye data for
nozzle no. 2 is changed to dye data according to colour i+1. [0100]
57. Check whether length D is equal to E.sub.2 which is the
distance between the first and third nozzles. [0101] 58. If
D=E.sub.2, dye data for nozzle no. 3 is changed to dye data
according to colour i+1. [0102] 59. Check whether distance D is
equal to E.sub.3 which is the distance between the first and fourth
nozzles. [0103] 60. If D=E.sub.3, dye data for nozzle no. 4 is
changed to dye data according to colour i+1. [0104] 61. Check
whether remaining thread consumption B.sub.1 for the colour is
equal to zero. If the answer is no, i.e. dyeing with the current
colour is not concluded, the program is repeated from step 43.
[0105] 62. Change of dyeing data for nozzle no. 1 to dyeing data
according to colour i+1.
[0106] D is reset to zero. Return to program in step no. 33.
[0107] If a dyer 15 has all nozzles for the different dye
components at the same point along the thread, this means only that
distances E.sub.1, E.sub.2, E.sub.3 are zero in the structure
above.
[0108] In the claims, terms such as "containing" and "including" do
not exclude the presence of other elements or steps. Furthermore,
although not listed individually, a multiplicity of arrangements,
elements or method steps can be implemented e.g. by the same unit.
In addition, although individual features can be included in
different patent claims, these can perhaps advantageously be
combined and the inclusion in different claims does not mean that a
combination of features is not suitable and/or advantageous.
Furthermore singular references do not exclude plurality. Thus
references to "one", "first", "second" etc. do not exclude a
multiplicity of occurrences unless explicitly stipulated.
Definitions
[0109] The colour change point is the point on the upper thread
which constitutes the border between two colours on a change of
colour on the upper thread.
[0110] Dye is the fluid or equivalent applied to the thread.
[0111] Colour is the shade of the dye which is desired in the
thread.
[0112] Thread length is the thread usage in a stitch.
[0113] When a distance to the sewing material is given, this is
considered throughout the description to be the distance to the
point on the sewing material where the current stitch is being
sewn.
* * * * *