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.

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.