JPH09192370A - Device for adjusting tension of sewing machine needle thread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high quality of a stitched product quality by controlling the takeup amount of a needle thread properly by a takeup lever when the stitching operation is begun, then appropriately adjusting the length of a needle thread which begins to be used for stitching to stabilize the remaining length of the needle thread at a needle point, and minimizing the bird nesting and eliminating a trouble with the stitching work such as the slipping-off of the needle thread which begins to be used for stitching or a skip stitch. SOLUTION: This device for adjusting the tension of a needle thread on a sewing machine is composed of a needle thread regulating device represented by either of a needle thread holding device 10 for holding a needle thread or a device 20 for applying a resistance to the needle thread by making a folded path for running the needle thread variable with the help of a fixed thread handling area guide and a movable auxiliary thread guide, between a sewing machine takeup lever 7 and a stitching needle 9. In addition, the device is equipped with a control device 28 for controlling the operation of the needle thread regulating device. Further, the needle thread regulating device is actuated by the control device 28 within the rotary angle of a main shaft of 50 deg.-100 deg. including a point near the dead center of the takeup lever 7 for the first few stitches. Thus the takeup amount of the needle thread 2 by the takeup lever 7 when the stitching operation is begun is properly controlled by holding or applying a resistance to the needle thread 2 between the takeup lever 7 and a stitching needle 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle thread tension adjusting device for stabilizing the needle thread length at the start of sewing in a sewing machine such as a lock stitch sewing machine.

[0002]

2. Description of the Related Art In order to minimize the occurrence of a so-called bird's nest in which the upper thread remaining on the needle tip is too long and is drawn deeply under the cloth at the next sewing after thread cutting of a sewing machine, after thread cutting Japanese Patent Application Laid-Open No. 6-1901 discloses a needle thread feeding / retracting device for easily adjusting the needle thread length with good reproducibility.
It is known from Japanese Patent Publication No. 71. This needle thread feeding / pulling-back device will be described between the first thread tensioner 12 and the second thread tensioner 14 by describing the reference numerals of the drawings in the publication.
A first gripping device 16 for gripping or releasing the upper thread 24 and a second
The gripping device 20 and the thread hoisting device 18 are provided between the gripping device 20 and the first and second gripping devices 16 and 20, and while turning the first and second gripping devices 18 on and off, the thread hoisting arm of the thread hoisting device 18 pulls out a predetermined amount of the thread from the bobbin winding side and ends the thread cutting After that, the thread is pulled back from the needle side by the thread hoisting arm 20B by the set amount by the needle tip needle thread length adjusting dial 30, and the needle tip needle thread length is adjusted.

Further, in a general lock stitch sewing machine, for example, the first thread tension member 100 is provided at a position as shown in FIG.
As shown in FIG. 11, the first thread tension member 100 is provided with a thread tension rod 101, a thread tension guide 102, a thread tension spring 103, a thread tension nut 104, and a thread tension disc 105.
Consists of According to such a first thread tension member 100, the thread tension nut 104 on the thread tension rod 101 is tightened, and the needle tip upper thread remaining length passing through the thread tension disc 105 is adjusted by the pressure of the thread tension spring 103. There is.

[0004]

However, in the needle thread feeding / pulling-back device known from Japanese Patent Laid-Open No. 6-190171, as described above, the thread pulling arm 20B pulls the thread back from the needle side after completion of thread cutting. Adjust the needle tip needle thread length, but if the needle tip needle thread length at this time is too short, the needle thread may slip off from the needle at the beginning of the next sewing or stitching problems such as stitch skipping may occur. I was worried.

Further, in the first thread tension member 100 of the general lock stitch sewing machine shown in FIGS. 10 and 11, the thread tension nut 104 on the thread tension rod 101 as described above is tightened and the pressure of the thread tension spring 103 is applied. There is a problem in that the remaining length of the upper thread is not stable because the method is to adjust the remaining length of the upper thread that passes through the thread tension disc 105.

Therefore, an object of the present invention is to appropriately control the sewing start length of the upper thread and properly control the needle tip by appropriately controlling the amount of lifting of the upper thread by the balance at the sewing start in the sewing machine. The needle thread remaining length is also stabilized to minimize the occurrence of bird's nests, as well as to eliminate stitching problems such as slipping out of the upper thread at the start of sewing and skipping stitches, and good sewing quality can be obtained. It is to provide a thread tension adjusting device.

[0007]

In order to solve the above problems, the invention according to claim 1 is an upper thread regulating device for regulating the upper thread between the balance of the sewing machine and the sewing needle by gripping or imparting resistance. And a control device for controlling the operation of the upper thread regulating device, the needle thread tension adjusting device comprising:
By the control device, the rotation angle of the main shaft (upper shaft) including the vicinity of the top dead center of the balance is 50 ° to 1 during the several stitches at the start of sewing.
By operating the upper thread restricting device within the range of 00 °, for example, turning on the solenoid to restrict the upper thread by gripping or applying resistance, the upper thread of the upper thread by the balance at the start of sewing is regulated. It is characterized by being configured to control the amount of pulling up.

As described above, the rotation angle of the main shaft (upper shaft) including the vicinity of the top dead center of the balance is 50 ° to 10 ° during the several stitches at the start of sewing.
By controlling the upper thread between the balance and the sewing needle within the range of 0 ° and appropriately controlling the amount of the upper thread pulled up by the balance at the start of sewing, the sewing start length of the upper thread is It can be adjusted appropriately, and the needle tip needle thread remaining length is stable. Therefore, since the sewing start length of the upper thread can be adjusted, the occurrence of bird's nests can be minimized and the upper thread can be prevented from being excessively pulled up by the balance. Eliminate stitching problems such as skipped stitches. As a result, good sewn product quality is obtained.

According to a second aspect of the present invention, in the needle thread tension adjusting device of the first aspect of the present invention, the upper thread restricting device passes the upper thread holding device for holding the upper thread or the upper thread. The invention is characterized in that the bending path is variably constituted by, for example, a fixed yarn path guide, a movable auxiliary yarn guide, or the like, and is one of the needle thread resistance imparting devices for imparting resistance to the needle thread.

As described above, as the upper thread restricting device, the upper thread gripping device grips the upper thread, or the upper thread resistance applying device applies resistance to the variable bending path by passing the upper thread. According to the first aspect of the present invention, the upper thread can be regulated between the balance and the sewing needle.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the needle thread tension adjusting device for a sewing machine according to the present invention will be described below with reference to FIGS. 1 to 9.

<First Embodiment> First, FIG. 1 is a schematic front view showing a main part of a first embodiment of a sewing machine to which the present invention is applied, and FIG. 2 is a direction of an arrow A in FIG. It is a schematic side view of the principal part seen from. In these FIGS. 1 and 2, 1
Is the sewing machine arm, 2 is the upper thread, 3 is the first thread tension, and 4 is the second
Thread tension, 5 and 6 are thread guides, 7 is a balance, 8 is a thread guide, 9 is a sewing needle, 10 is an upper thread regulating device (upper thread grasping device), 11 is an upper thread grasping solenoid, and 12 is an upper thread grasping plate. , 13 are control devices.

As shown in FIG. 1, the sewing machine arm 1 is provided with a first thread tensioner 3, a second thread tensioner 4, thread guides 5, 6 along a path from an unillustrated bobbin thread to a sewing needle 9 of an upper thread 2. ,
The balance 7 and the thread guide 8 are provided in this order. In the first embodiment, between the balance 7 and the sewing needle 9, and
An upper thread gripping device 10, which is an upper thread restricting device, is provided in a path below the thread guide 8. As shown in FIG. 2, the needle thread gripping device 10 includes an upper thread gripping solenoid 11 and an upper thread gripping plate 12.
It is provided with. This needle thread grasping solenoid 11
ON (excitation by energization) operation causes needle thread grip plate 12
It is possible to pinch and grasp the upper thread 2 passing between the upper thread grasping solenoid 11 and the main body of the upper thread grasping solenoid 11. Also, when the upper thread grasping solenoid 11 is turned off (demagnetized by interruption of energization),
The upper thread 2 is released from the grip, and the upper thread 2 freely passes between the upper thread grip plate 12 and the main body of the upper thread grip solenoid 11.

In the illustrated example, the upper thread gripping device 10 is arranged between the thread guide 8 and the sewing needle 9, but the upper thread gripping device 10 is arranged at a place between the balance 7 and the sewing needle 9. It can be anywhere Further, in the illustrated example, since the needle thread gripping solenoid 11 is installed outside the sewing machine arm 1, a bracket (not shown) is required to support the needle thread gripping solenoid 11. However, the needle thread gripping solenoid 1 is provided inside the sewing machine arm 1.
1 may be accommodated. Above needle thread gripping device 1
The ON / OFF operation of the needle thread grasping solenoid 11 at 0 is performed by a control signal from the control device 13 as described later.

Next, an example of control of the ON / OFF operation of the needle thread gripping solenoid 11 by the control device 13 will be described. FIG. 3 is a timing chart exemplifying the grasping of the upper thread 2 according to the present invention. In the figure, UDET indicates a sewing needle (sewing needle 9) upper position detection signal indicating that the UDET is at the needle bar upper position when ON, DDET is Sewing machine needle (sewing needle 9) lower position detection signal indicating that the needle bar is at the lower position when turned on, grip SOL
Is an upper thread gripping solenoid 1 that grips the upper thread 2 when it is turned on.
A control signal of 1 is also used, and a balance curve having a main axis (upper axis) angle at which the top dead center of the sewing needle 9 is 0 ° as the horizontal axis and the upper axis angle of 67 ° as the top dead center of the balance 7 is also included. It is also shown.

In the timing chart of FIG. 3,
In response to a control signal from the control device 13, the needle thread grasping solenoid 11 is turned on in a certain section between the several stitches at the start of sewing,
The upper thread 2 passing between the main body of the upper thread gripping solenoid 11 and the upper thread gripping plate 12 is sandwiched and gripped. That is, as shown in the figure, the top dead center of the balance 7 (upper axis angle 67 °)
The needle thread gripping solenoid 11 is turned on in the range of the upper axis angle of 50 ° to 100 ° including the vicinity, and the needle thread 2 is sandwiched between the main body of the needle thread gripping solenoid 11 and the needle thread gripping plate 12 and gripped. To do. Here, the ON time t of the needle thread gripping solenoid 11, the timing of the time t (ON time), and the number N of needles for turning on the needle thread gripping solenoid 11 can be arbitrarily adjusted / changed. After a predetermined number of stitches, the needle thread gripping solenoid 11 is turned off (deenergized by shutting off the electric current) to release the needle thread 2, and the needle thread gripping plate 12 is released.
The normal sewing state in which the upper thread 2 freely passes between the upper thread grip solenoid 11 and the main body of the upper thread grip solenoid 11 is set.

FIG. 4 is a timing chart exemplifying the grasping of the upper thread 2 by the balance 7 for preventing the upper thread 2 from being excessively pulled up. Like FIG. 3, UDET is a signal for detecting the sewing machine needle upper position, DDET is a signal for detecting the needle lower position of the sewing machine, SOL is a control signal for the upper thread gripping solenoid 11, and L
SiO is a sewing machine rotation command signal indicating that the sewing machine is in a rotating state when ON, TG is a sewing machine upper shaft encoder, and a sewing machine start command point and a sewing machine rotation start point are also shown. In the timing chart of FIG. 4, the grasping control of the upper thread 2 for preventing the upper thread 2 from being excessively pulled up by the balance 7 is performed as follows.

(1) It is applied only when the sewing machine is started after thread cutting. (2) After the sewing machine starts rotating (LSiO is ON), DDET
The counting of the upper shaft angle of the sewing machine is started by turning on (see TG), the needle thread gripping solenoid 11 is turned on at an angle X, and turned off at an angle Y. At this time, the angle count is DDE
Reset to zero by turning on the T input. (3) At the same time, the number of stitches is counted (see DDET), and the above operation (2) is repeated up to N stitches. (4) After the Nth needle, the normal sequence control in which the needle thread grasping solenoid 11 is not turned on is returned to.

As described above, according to the needle thread tension adjusting device of the sewing machine according to the first embodiment of the present invention, the following effects can be obtained. (1) Turn on the needle thread gripping solenoid 11 within the range of the upper axis angle of 50 ° to 100 ° including the vicinity of the top dead center (upper axis angle of 67 °) of the balance 7 during several stitches at the start of sewing, By grasping the upper thread 2 and appropriately controlling the pulling amount of the upper thread 2 by the balance 7, the sewing start length of the upper thread 2 can be appropriately adjusted,
Moreover, the needle tip upper thread remaining length is stable. (2) Since it is possible to prevent the upper thread 2 from being excessively pulled up by the balance 7, the upper thread 2 at the start of sewing does not come off or skip. (3) By changing the ON timing of the upper thread gripping solenoid 11 depending on the position of the upper thread gripping device 10, the sewing start length of the upper thread 2 can be adjusted.

<Second Embodiment> FIG. 5 shows an essential part of a second embodiment of a sewing machine to which the present invention is applied. FIG. 6 is a schematic side view showing an upper thread resistance applying state by a thread resistance applying apparatus, and FIG. 6 is an enlarged schematic perspective view showing the upper thread resistance applying apparatus. In these FIGS. 5 and 6, 1 is the sewing machine arm and 2 is the same as in the above-described first embodiment.
Is a needle thread, 7 is a balance, 9 is a sewing needle, 18 is a thread guide,
20 is an upper thread regulating device (upper thread resistance imparting device), 21 is a yarn path guide, 22 and 23 are auxiliary yarn guides, 24 is a connecting link,
Reference numeral 25 is a lever, 26 is a needle thread bending path solenoid, 27 is a plunger, and 28 is a control device.

In the second embodiment, as shown in FIG. 5, the sewing machine arm 1 is provided with a needle thread resistance imparting device, which is a needle thread regulating device, between the balance 7 and the needle bar thread guide 18. Two
0 is provided. The needle thread resistance imparting device 20 has a pair of parallel auxiliary thread guides 22 and 23 which are vertically separated from each other with respect to an L-shaped rod-shaped thread path guide 21 fixed to the sewing machine arm 1 side.
Is capable of advancing and retracting, that is, as shown in FIG. 6, a pair of upper and lower auxiliary thread guides 22 and 23 are connected to the connecting link 24.
It is equipped with a screw at the tip of. The connecting link 24 has an intermediate portion supported by a swingable lever 25 provided in the sewing machine arm 1, and a rear end portion thereof is connected to a plunger 27 of a needle thread bending path solenoid 26.

The needle thread bending path solenoid 26 is turned on.
By the (excitation by energization) operation, the plunger 27 projects from the main body of the upper thread bending path solenoid 26, and the pair of upper and lower auxiliary thread guides 22 and 23 advance through the connecting link 24, as shown in FIGS. 5 and 6. Thus, the auxiliary yarn guides 22 and 23 are located in parallel above and below the fixed yarn guide 24.
Therefore, the upper yarn 2 passing between the fixed yarn path guide 24 forming the bending path and the auxiliary yarn guides 22 and 23 above and below it,
Resistance can be imparted by the bending path.
Further, when the upper thread bending path solenoid 26 is turned off (demagnetized by shutting off the current), the pair of auxiliary thread guides 22 and 23 retract, and as shown in FIG. 8, the separated yarn path guide 21 and auxiliary thread guide 22, The upper thread 2 freely passes between the two.

In the illustrated example, the needle thread resistance imparting device 20 is disposed between the balance 7 and the needle bar thread guide 18, but the disposing position of the needle thread resistance imparting device 20 is the above-mentioned first position.
Similar to the embodiment, the position between the balance 7 and the sewing needle 9 may be anywhere. Further, in the illustrated example, the connection link 24 and the lever 25 are provided between the plunger 27 of the upper thread bending path solenoid 26 and the pair of auxiliary thread guides 22 and 23.
Alternatively, the pair of auxiliary yarn guides 22 and 23 may be directly connected to 7. Furthermore, the configuration of the bending path that imparts resistance to the needle thread 2 is not limited to the combination of the fixed yarn path guide 21 and the movable auxiliary yarn guides 22 and 23 in the illustrated example, and is arbitrary. The ON / OFF operation of the upper thread bending path solenoid 26 of the upper thread resistance applying device 20 is performed by a control signal from the control device 28 as described later.

First, in the same way as the flow chart shown in FIG. 3 in the above-mentioned first embodiment, the control device 2
In accordance with a control signal from 8, the upper thread angle of the upper thread angle is in the range of 50 to 100 degrees including the vicinity of the top dead center (upper axis angle of 67 degrees) of the balance 7 during the several stitches at the sewing start.
Is turned on, resistance is applied to the upper thread 2 by the bending path composed of the fixed thread guide 24 and the auxiliary thread guides 22 and 23 above and below the thread guide, and the pulling amount of the upper thread 2 by the balance 7 is appropriately controlled. (See Figure 7). Then, after the predetermined number of stitches, the upper thread bending path solenoid 26 is turned off (demagnetization by interruption of energization).
Then, the pair of auxiliary thread guides 22 and 23 are retracted to
As shown in, the normal sewing state in which the upper thread 2 freely passes between the separated yarn path guide 21 and the auxiliary thread guides 22 and 23 is established.

Next, the timing chart shown in FIG. 9 will be described. FIG. 9 is a timing chart exemplifying application of resistance to the upper thread 2 according to the present invention.
As in the case of FIG. 4 in the above embodiment, LSiO is a sewing machine rotation command signal, UDET is a sewing machine needle upper position detection signal, and DDET is a sewing machine needle lower position detection signal.
TRM is the thread trimming solenoid control signal, and SOLA is ON
Sometimes a control signal of the small upper thread bending path solenoid 26,
SOLB is a large-diameter upper thread bending path solenoid 2 when ON
6 control signal, bending motion (CYLA) is ON / OF by a return-type cylinder instead of the needle thread bending path solenoid 26.
At F, a control signal for a large / small bending upper thread bending path cylinder. The sewing machine start command point, the sewing machine rotation start point, the thread trimming operation point, the sewing machine stop command point, and the actual sewing machine stop point are also shown.

First, in the case of the small needle thread bending path solenoid 26 which is bent when turned on, the upper thread bending path solenoid 26 is turned on (see tx) for a few stitches at the start of sewing as in SOLA, and the auxiliary thread guide 22 , 23 are advanced, sewing is started, and after a few stitches, the upper thread bending path solenoid 26 is turned off to return to the normal upper thread path, and sewing is continued. Also, O
In the case of the needle thread bend path solenoid 26 that is large and bends at N,
Like SOLB, when the thread cutting solenoid is turned on (see TRM), the upper thread bending path solenoid 26 is turned on to perform thread cutting in the state of the upper thread bending path, or the needle thread bending path solenoid is adjusted at an arbitrary position. 26 is turned on and stopped in the state of the normal upper thread path (see the portion shown by the dotted line where the ON timing can be adjusted).

Further, in place of the upper thread bending path solenoid 26, a large / small upper thread bending path cylinder may be used which is turned on / off by a backward movement type cylinder. In that case,
Like the bending operation (CYLA), the needle thread bending path cylinder is turned on for a few stitches at the beginning of sewing, and the auxiliary thread guides 22 and 23 are advanced farther than the thread path guide 21 to sew in a state of a large needle thread bending path. After a few stitches, the needle thread bending path cylinder is turned off and returns to the small needle thread bending path, and sewing is continued. Then, the thread cutting solenoid is turned on (see TRM).
At the same time, the upper thread bending path cylinder is turned on to perform thread cutting in the state of a large upper thread bending path, or the adjustment is made to turn on the upper thread bending path cylinder at an arbitrary position to stop in the state of a small upper thread bending path. (Refer to the part shown in dotted line where the ON timing can be adjusted). In this way, the auxiliary thread guide 22,
It is also possible to arbitrarily adjust the protruding amount of 23.

As described above, according to the needle thread tension adjusting device of the sewing machine according to the second embodiment of the present invention, the following effects can be obtained. (1) Between the several stitches at the start of sewing, including the vicinity of the top dead center (upper shaft angle 67 °) of the balance 7, the upper shaft angle is in the range of 50 ° to 100 °, and the fixed thread guide 24 and its upper and lower parts. Auxiliary thread guide 2
By giving a bending resistance to the upper thread path by the bending path composed of 2 and 23, the pulling amount of the upper thread 2 by the balance 7 can be controlled, the sewing start length of the upper thread 2 can be appropriately adjusted, and the needle The remaining length of the top needle thread is stable. (2) Since it is possible to prevent the upper thread 2 from being excessively pulled up by the balance 7, the upper thread 2 at the start of sewing does not come off or skip. (3) It does not affect the quality of normal sewing products.

In each of the above embodiments,
Although the solenoid or the air cylinder is used as the actuator of the needle thread gripping device or the needle thread resistance applying device as the needle thread restricting device, the present invention is not limited to this, and may be another actuator such as a pulse motor. May be. Further, the configuration and arrangement position of the needle thread gripping device and the needle thread resistance imparting device as the needle thread restricting device are not limited to the embodiments described above, and other specific detailed structures and the like are also applicable. Of course, it can be changed appropriately.

[0030]

As described above, according to the needle thread tension adjusting device of the invention according to the first aspect of the invention, the rotation angle of the main shaft including the vicinity of the top dead center of the balance is 50 during a few stitches at the start of sewing.゜ ~
By controlling the upper thread between the balance and the sewing needle within the range of 100 ° and appropriately controlling the amount of pulling of the upper thread by the balance at the start of sewing, the sewing start length of the upper thread is In addition to being able to adjust it properly, the needle tip needle thread remaining length is also stabilized, so that the occurrence of bird's nests can be minimized, and the needle thread is prevented from being pulled up excessively by the balance and sewing is performed. It is possible to eliminate stitching problems such as slipping out of the upper thread at the beginning and stitch skipping. Therefore, good sewn product quality can be obtained.

According to the needle thread tension adjusting device of the invention of claim 2, the needle thread gripping device for regulating the needle thread between the balance and the sewing needle as in the invention of claim 1 is used. The device can grip the upper thread, and the upper thread resistance applying device can apply resistance to the variable bending path through the upper thread.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a main part of a first embodiment of a sewing machine to which the present invention is applied.

FIG. 2 is a schematic side view of the main part as seen from the direction of arrow A in FIG.

FIG. 3 is a timing chart illustrating the upper thread grip according to the present invention.

FIG. 4 is a timing chart exemplifying grasping of an upper thread by a balance to prevent excessive pulling of the upper thread.

FIG. 5 shows essential parts of a second embodiment of a sewing machine to which the present invention is applied, in which a needle thread resistance applying device (upper thread resistance applying device) applies an upper thread resistance at a needle upper stop position. It is the schematic side view which showed.

FIG. 6 is an enlarged schematic perspective view of the needle thread resistance imparting device of FIG.

FIG. 7 is a schematic side view showing an upper thread resistance application state by the upper thread resistance application device from the start of sewing to several stitches, following FIG. 5;

FIG. 8 is a schematic side view following FIG. 7, showing normal sewing in a needle thread resistance released state by the needle thread resistance imparting device after several stitches;

FIG. 9 is a timing chart exemplifying application of needle thread resistance according to the present invention.

FIG. 10 is a schematic front view showing a main part of a conventional general lockstitch sewing machine.

11 is an enlarged side view showing the first thread tension of FIG. 10. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sewing machine arm 2 Upper thread 7 Balance 9 Sewing needle 10 Upper thread regulating device (upper thread grasping device) 11 Upper thread grasping solenoid 12 Upper thread grasping plate 13 Control device 20 Upper thread regulating device (upper thread resistance imparting device) 21 Thread path Guide 22, 23 Auxiliary thread guide 24 Connection link 25 Lever 26 Upper thread bending path solenoid 27 Plunger 28 Control device

Claims (2)

[Claims] 1. Between the balance of the sewing machine and the sewing needle,
What is claimed is: 1. A needle thread tension adjusting device for a sewing machine, comprising: an upper thread restricting device for restricting an upper thread; and a control device for controlling the operation of the upper thread restricting device. The balance at the beginning of sewing is operated by operating the needle thread restricting device within a range of a rotation angle of the main shaft including the vicinity of the top dead center of the balance of 50 ° to 100 ° to restrict the upper thread. A needle thread tension adjusting device for a sewing machine, which is configured to control the amount of pulling up of the needle thread by the sewing machine. 2. The upper thread restricting device is an upper thread gripping device for gripping the upper thread or an upper thread resistance applying device for variably configuring a bending path through which the upper thread passes to apply resistance to the upper thread. The needle thread tension adjusting device according to claim 1, wherein the needle thread tension adjusting device is any one of the above.