JPH0579359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a needle thread supplying device that accurately feeds a required amount of needle thread by turning on and off a thread holding device.

[Prior Art] The present applicant has proposed a sewing machine needle thread supply device shown in FIG. 4, which supplies needle thread by turning on and off a thread holding device. In FIG. 4, a needle thread 2 from a thread supply source 1 such as a thread spool, which is a needle thread supply source, passes through a first thread holding device 3 consisting of a solenoid, a roller 4, and a second thread holding device 5 consisting of a solenoid. , is hooked on a balance 6 and passed through the stitches of a needle 7. Further, a roller up solenoid 8 that presses and releases the roller 4 is connected to the roller 4, a workpiece 10 is placed on the throat plate 9, and a thread cutter 11 is attached below the throat plate 9. has been done.

To explain the operation of the conventional sewing machine configured in this way, first, the first thread holding device 3 is turned off so that the upper thread 2 is not restricted at all, and the second thread holding device 5 is turned on and the upper thread is turned off. Hold the thread. In this state, the roller 4 in close contact with the needle thread 2 rotates in the direction of the arrow, and the needle thread 2 is let out from the thread supply source 1. When the required amount of upper thread 2 has been let out, the first thread holding device 3 is turned on to hold the free upper thread 2, and the second thread holding device 5 is turned off to hold the upper thread 2. Release upper thread 2. Here, the balance 6
is raised, the needle thread 2 that was between the roller 4 and the second thread holding device 5 is paid out toward the needle 7, tension is applied between the first thread holding device 3 and the stitch, and the stitch is sewn. Tightened by the strength of the plan.

Next, in the case of thread trimming, when the thread trimming signal is turned on, the first thread holding device 3 and the second thread holding device 5
is turned off, and the upper thread 2 held by the first and second thread holding devices 3 and 5 is released. Then, the roller 4 is rotated to set the thread payout amount of the upper thread 2 during thread trimming, and when the required amount of the needle thread 2 is paid out,
The first thread holding device 3 is turned on to hold the upper thread 2. In this state, the upper thread 2 is cut with the thread cutter 11 to execute thread trimming. When this thread trimming is completed, the thread trimming signal is turned off.

By turning off this thread trimming signal, the first thread holding device 3 is turned off, the upper thread 2 held therein is released, and furthermore, the roller up solenoid 8 is turned on to separate the rollers 4, and the upper thread 2 is released. The thread was completely free.

[Problems to be Solved by the Invention] As described above, in the conventional upper thread supply device, after thread cutting, the first and second thread holding devices 3 and 5 are turned off,
In addition, the roller up solenoid 8 is turned on to release the needle thread 2 from the roller 4, so that the needle thread is completely free. Therefore, when the workpiece 10 is pulled, the needle thread 2 is also supplied. There was a problem in that the upper thread was pulled out from the upper thread source 1, and an appropriate amount of upper thread remained could not be secured after the thread was trimmed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a needle thread supply device that can always hold the same remaining amount of needle thread when a workpiece is removed from a sewing section of a sewing machine after thread cutting.

[Means for Solving the Problems] In order to achieve the above object, the present invention is provided between a thread take-up lever and an upper thread supply source, and rotates the upper thread by engaging the upper thread with the upper thread, thereby removing the upper thread from the upper thread supply source. A thread holding device is provided that holds the needle thread by applying a voltage to a roller to feed it out, and voltage is applied to the thread holding device when the amount of needle thread required for one stitch has been paid out each time one stitch is formed. The needle thread supply device is designed to stop feeding out the needle thread by holding the needle thread, and the needle thread supply device operates in response to a thread trimming signal to cut the sewing thread including the needle thread below the workpiece. The sewing machine is equipped with a control means for applying a voltage to the thread holding device for a predetermined period of time in response to disappearance of the thread cutting signal.

[Operation] According to the present invention, when thread trimming is performed, after the thread cutter cuts the upper thread, the first
By turning off the thread holding device and applying voltage to the second thread holding device to hold the needle thread, the needle thread is restrained by the second thread holding device even when the material to be sewn is pulled. Therefore, the upper thread is prevented from being let out from the upper thread supply source.

[Embodiment] Referring to FIG. 1, in the needle thread supply device according to one embodiment of the present invention, a thread trimming signal 13 and a thread payout amount setting device 14 at the time of thread trimming are provided on the input side of a control device (CPU) 12. A storage device 15 of ROM and RAM is also connected. Furthermore, a first solenoid drive circuit 16 for driving the first yarn holding device 3 shown in FIG. 4 is provided on the output side of the control device 12;
A second solenoid drive circuit 17 that drives the second thread holding device 5, a roller up solenoid drive circuit 18 that drives the roller up solenoid 8 that releases the roller 4, and a motor drive control circuit 19 are connected to the motor drive control circuit. A motor 20 for rotating the roller 4 is connected to the roller 19 .

Next, the operation of this embodiment will be explained with reference to the time chart in FIG. 2, the flow chart in FIG. 3, and the conventional example in FIG. 4. First, when the thread trimming signal 13 is turned on, {see FIG. 2b}, the first solenoid drive circuit 16 and the second solenoid drive circuit 17 are turned off {see FIGS. 2d and e}, and the first The needle thread 2 held by the second thread holding device 3 and the second thread holding device 5 is released. At the same time, in order to execute the yarn payout amount set by the yarn payout amount setting device 14, the motor drive control circuit 19 is turned on to drive the motor 20, and the roller 4 is rotated in the direction of the arrow to remove the yarn from the yarn supply source 1. Pay out upper thread 2. and,
When the set amount of needle thread 2 is let out from the thread supply source,
By turning on the first solenoid drive circuit 16 {see FIG. 2 d}, the first thread holding device 3 holds the upper thread 2 and prevents the upper thread from being further paid out from the thread supply source. Then, the upper thread is cut by the thread cutter 11, and when this thread cutting is completed, the thread trimming signal is turned off {see FIG. 2b}.

As a result, the second solenoid drive circuit 17
is turned on so that the second thread holding device 5 holds the upper thread 2, the first solenoid drive circuit 16 is also turned off (see FIG. 2e), and the first thread holding device 3 is released. At the same time, the upper thread retention timer in the control device is activated {see FIG. 2a}. Further, the roller up solenoid drive circuit 18 is turned on, and the roller 4 holding the upper thread 2 is released. At the same time, a roller up timer in the control device is activated. When this roller up timer time exceeds,
Turn off the roller up solenoid 18 {second
See Figure b}. When the upper thread holding timer time expires, the second solenoid drive circuit 17 is turned off and the upper thread 2 held by the second thread holding device 5 is removed.
is released and the upper thread is completely free.

In this manner, when thread trimming is performed, after the thread cutter 11 cuts the upper thread, the first solenoid drive circuit 16 is turned off for a certain period of time, the first thread holding device 3 is released, and the second thread holding device 3 is released. Solenoid drive circuit 17
is turned on to cause the second thread holding device 5 to hold the upper thread. As a result, even if the material to be sewn is pulled, the needle thread 2
Since the needle thread is restrained by the second thread holding device 5, the needle thread is not let out from the thread supply source.

In the above embodiment, the second solenoid drive circuit is turned on for a certain period of time after thread trimming, but the first
The solenoid drive circuit may be turned on, or both of these drive circuits may be turned on.

[Effects of the Invention] Since the present invention is configured as described above,
When the thread trimming signal turns on, the roller pays out the amount of needle thread set by the thread payout amount setting device, so after thread trimming, there is always an appropriate amount of needle thread remaining, which can be used for the next sewing. The advantage is that the first seam is tightened correctly when starting work.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control circuit for controlling a needle thread supply device according to an embodiment of the present invention, FIG. 2 is a time chart explaining the operation of the control circuit of FIG. 1, and FIG.
This figure is a flowchart for explaining the operation of the control circuit shown in FIG. 1, and FIG. 4 is a schematic diagram of the needle thread supply device of this type of sewing machine. DESCRIPTION OF SYMBOLS 1... Yarn supply source, 2... Needle thread, 3... First thread holding device, 4... Roller, 5... Second thread holding device, 8... Roller up solenoid, 12... Control device , 13...Thread trimming signal, 14...Thread payout amount setting device, 15...Storage device, 16...First
solenoid drive circuit, 17... second solenoid drive circuit, 18... roller up solenoid drive circuit, 19... motor drive control circuit, 20...
motor.

Claims (1)

[Claims] 1. A roller that engages with the needle thread and rotates to let out the needle thread from the needle thread supply source, and a thread holding device that holds the needle thread by applying a voltage are provided between the thread take-up and the needle thread supply source. For each stitch formation, when the amount of needle thread required for one stitch has been paid out, a voltage is applied to the thread holding device to hold the needle thread, thereby stopping the feeding of the needle thread. In a sewing machine having a thread supply device and a thread trimming device that operates in response to a thread trimming signal and cuts sewing thread including an upper thread below the workpiece, the thread holding device 1. A needle thread supply device for a sewing machine, comprising a control means for applying a voltage to the needle thread for a certain period of time.