JP7624739B2 - Sewing machine thread tension control device and sewing machine thread tension applying device - Google Patents

Description

The present invention relates to a device that applies tension to the upper thread of a sewing machine.

A conventional thread tension control device for controlling the tension of the upper thread in a sewing machine is shown in Patent Document 1.

That is, the thread tension control device of Patent Document 1 includes a support member 12 arranged on the thread path from the thread spool to the thread take-up lever, a thread take-up spring 14 rotatably supported by the support member and having a thread hook at its tip, a thread tension adjustment member 3 arranged on the thread path and capable of applying tension to the thread, a drive means (magnet 11) that drives the thread tension adjustment member and varies the thread tension, a detection means (detection plate 13 and proximity sensor 15) that detects the rotational position of the thread take-up spring, and a control device 22 that controls the drive means to increase or decrease the thread tension based on the detection output of the detection means during the bobbin tightening section of the sewing machine main shaft phase, comparing it with a set value, detects the thread tension from the displacement of the thread take-up spring 14, compares the detected thread tension with the set value, calculates the increase or decrease in thread tension, and the control device 22 supplies a control current to the drive means based on the calculated thread tension.

In the thread tension control device of Patent Document 1, when the drive means (magnet 11) is excited, the movable iron core 10 is attracted, and the attracting action of the movable iron core 10 moves the pair of thread tension discs 8 and 9, and tension is applied to the thread between the pair of thread tension discs 8 and 9.

In addition, in the thread tension adjusting device of Patent Document 2, in a thread tension adjusting device 2 that adjusts the tension applied to the thread Y sandwiched between the opposing surfaces 211, 221 of the first and second disks 21, 22 facing each other, the first disk 21 is configured to be movable toward and away from the second disk 22 on the same axis 23, a permanent magnet 24 is provided on the first disk 21, and an electromagnet 25 is provided on the second disk 22, the magnetic pole of which is changeably connected to a power source and the amount of current flowing therethrough is changeable, and a coil spring 27 is provided that constantly biases the first disk 21 toward the second disk 22. By changing the magnetic pole of the electromagnet 25, an attractive force and a repulsive force are obtained with respect to the polarity of the permanent magnet 24, and the attractive force and the repulsive force with respect to the permanent magnet 24 can be varied according to the amount of current flowing. That is, the force of the coil spring 27 increases due to the attractive force when the magnetic poles of the electromagnet 25 are changed to a polarity different from that of the permanent magnet 24, and decreases due to the repulsive force when the magnetic poles of the electromagnet 25 are changed to the same polarity as the permanent magnet 24.

JP 2004-8713 A JP 2020-204106 A

However, in the thread tension control device of Patent Document 1, the movable iron core 10 is attracted by exciting the drive means (magnet 11), and tension is applied to the thread between the pair of thread tension discs 8, 9. This causes a problem in that it takes time for the drive means to respond from excitation to applying thread tension, making it impossible to obtain a high-speed response.

In other words, when the movable core 10 is attracted, the head 10a of the movable core 10 moves toward the thread tension adjustment member cover part 3a, and when the head 10a moves, the thread tension disc 8 is pushed by the head 10a and moves, and when the thread tension disc 8 moves, the thread tension disc 9 is pushed by the thread tension disc 8 and moves until it comes into contact with the thread tension adjustment member cover part 3a, and thread tension is applied with the thread tension disc 8 in close contact with the thread tension disc 9 while the thread tension disc 9 is in contact with the thread tension adjustment member cover part 3a. Therefore, even if the response time for the movement of the movable core 10 itself is short, it takes time for thread tension to be applied.

In addition, in the thread tension adjusting device of Patent Document 2, the response of thread tension application can be made faster by changing the polarity of the electromagnet 25 to attract/repel it with the permanent magnet 24. However, since the permanent magnet 24 is provided, simply cutting off the excitation of the electromagnet 25 will result in the permanent magnet 24 being attracted to the magnetic body of the electromagnet 25, and in order to cut off the application of thread tension, the electromagnet 25 must be continuously reverse-excited so that it repels the permanent magnet 24. In other words, to switch between applying thread tension and cutting off thread tension, the polarity must be changed while the electromagnet 25 is constantly excited.

The present invention aims to provide an upper thread tension control device that can apply upper thread tension by detecting the displacement of the thread take-up spring, can respond to tension application quickly, and can cut off thread tension application without continuously reverse-exciting the electromagnet.

The present invention has been created to solve the above problems, and firstly, a thread tension control device for a sewing machine provided upstream of a thread take-up lever in an upper thread path, the device having a thread take-up spring mechanism (5), a thread tension applying section (105) and a control section (316), the thread take-up spring mechanism comprising a fixed unit (9) which is detachably fixed to the sewing machine, a thread take-up spring provided in the fixed unit, a fixed section (52) fixed to the fixed unit, and a thread locking unit which is connected to the fixed section and rotates relative to the fixed section, the thread locking section (56) at which the upper thread is locked. the thread take-up spring (51) having a thread locking unit (57) having a thread locking unit with a magnet part (64) fixed to the thread locking unit, and a magnetic sensor (80) fixed to the fixed unit, the magnetic sensor being disposed opposite the magnet part when the thread locking unit is not rotated relative to the fixed unit, and the thread tension imparting part comprises a first electromagnet holder (120) having a first storage part (132) for storing the first electromagnet, and a second electromagnet holder (140) having a second storage part (152) for storing the second electromagnet. an electromagnet holder unit (119) having a first electromagnet holder and a second electromagnet holder provided with a gap between them, an opening (132K) is provided on the second electromagnet holder side of the first storage section, and an opening (152K) is provided on the first electromagnet holder side of the second storage section, the two openings being provided opposite each other; and a first electromagnet having an attraction surface (162a) on the second electromagnet side, when the second electromagnet holder side of the first storage section is the left side and the first electromagnet holder side of the second storage section is the right side, A first electromagnet (160) is housed in the first storage section so as to be movable in the left-right direction; a second electromagnet (170) having an attracting surface (172a) on the first electromagnet side and housed in the second storage section so as to be movable in the left-right direction; a first thread pressing plate (180) provided between the first and second electromagnets and having a plate-shaped portion (182) facing the attracting surface of the first electromagnet; and a second thread pressing plate (192) provided between the first and second electromagnets and closer to the second electromagnet than the first thread pressing plate and having a plate-shaped portion ( 192 ) facing the attracting surface of the second electromagnet. and a fixing member (110) for removably fixing the electromagnet holder unit to the sewing machine. In the thread take-up spring mechanism, the upper thread is engaged with the thread engaging portion, the thread engaging portion being provided on the upstream side of the thread take-up spring mechanism in the upper thread path. The thread tension applying portion is provided on the upstream side of the thread take-up spring mechanism in the upper thread path. The upper thread path is provided between the first thread presser disk and the second thread presser disk. The control portion controls the thread engaging portion so that the thread engaging portion rotates when the thread take-up spring pulls the upper thread, and as the thread engaging portion rotates, the distance between the magnet portion and the magnetic sensor becomes longer, and the value of the magnetic force of the magnet portion detected by the magnetic sensor becomes greater than the predetermined value. When the value of the magnetic force of the magnet part detected by the magnetic sensor becomes smaller than a predetermined value, the first electromagnet and the second electromagnet are excited to attract each other, thereby clamping the upper thread between the plate-shaped portion of the first thread presser disc and the plate-shaped portion of the second thread presser disc, and tension is applied to the upper thread. On the other hand, when the state in which the thread take-up pulls the upper thread is released, the thread locking unit rotates to shorten the distance between the magnet part and the magnetic sensor, and the value of the magnetic force of the magnet part detected by the magnetic sensor becomes equal to or greater than a predetermined value, the excitation of the first electromagnet and the second electromagnet is stopped to release the attraction between the first electromagnet and the second electromagnet, thereby releasing the application of tension to the upper thread.

Therefore, when applying tension to the yarn, it is sufficient to excite the first and second electromagnets so that they are attracted to each other. In particular, by simultaneously exciting the first and second electromagnets, the first and second electromagnets can be attracted to each other quickly, allowing for a high-speed response in applying tension.

In addition, when cutting off the application of yarn tension, the supply of current to the first electromagnet and the second electromagnet can be stopped, without reverse exciting the electromagnets. In addition, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, the excitation of the first electromagnet and the second electromagnet can be quickly cut off, allowing for a high-speed response when cutting off tension.

In addition, when no tension is applied to the thread, the current supply to the first and second electromagnets can be stopped, and there is no need to continue to reverse-excite the electromagnets. This makes it possible to suppress heat generation in the first and second electromagnets and to reduce the size of the first and second electromagnets.

In addition, since the thread tension is applied by two electromagnets, a large thread tension can be applied, and as a result, a wide range of thread tension can be applied, from no thread tension to a large thread tension.

In addition, the first and second electromagnets are controlled according to the detection results of the magnetic sensor based on the behavior of the thread locking unit in the thread take-up spring mechanism, and are not related to other control signals in the control unit of the sewing machine, making it easy to install on existing sewing machines.

Furthermore, the thread take-up spring mechanism is provided with a fixing unit that is removably fixed to the sewing machine, and the thread tensioning unit is provided with a fixing member for removably fixing the electromagnet holder unit to the sewing machine. Since the thread take-up spring mechanism and the thread tensioning unit are formed separately, when attaching the thread tension control device to an existing sewing machine, the attachment positions of the thread take-up spring mechanism and the thread tensioning unit can be adjusted, making it easy to attach to an existing sewing machine.

Secondly, there is provided a thread tension control device for a sewing machine provided upstream of a thread take-up lever in an upper thread path, the device having a thread take-up spring mechanism (5), a thread tension applying section (105) and a control section (316). The thread take-up spring mechanism comprises a fixed unit (9) which is detachably fixed to the sewing machine, a thread take-up spring provided in the fixed unit, a fixed section (52) fixed to the fixed unit, and a thread locking unit (57) which is connected to the fixed section and rotates relative to the fixed section and has a thread locking section (56) at which the upper thread is locked. The electromagnet holder unit includes a spring (51), a magnet section (64) fixed to the thread locking unit, and a magnetic sensor (80) fixed to the fixed unit and arranged to face the magnet section when the thread locking unit is not rotated relative to the fixed unit, and the thread tension imparting section includes a first electromagnet holder (120) having a first storage section (132) for storing a first electromagnet, and a second electromagnet holder (140) having a second storage section (152) for storing a second electromagnet. a first electromagnet holder and a second electromagnet holder are provided with a gap between them, an opening (132K) is provided on the second electromagnet holder side of the first storage section, and an opening (152K) is provided on the first electromagnet holder side of the second storage section, and the two openings are provided opposite each other in an electromagnet holder unit (119); and a first electromagnet having an attraction surface (162a) on the second electromagnet side, when the second electromagnet holder side of the first storage section is the left side and the first electromagnet holder side of the second storage section is the right side, the electromagnet holder unit (119) can move in the left-right direction. a first electromagnet (160) housed in the first storage section so as to be movable in the left-right direction; a second electromagnet (170) having an attracting surface (172a) on the first electromagnet side and housed in the second storage section so as to be movable in the left-right direction; a first thread pressing plate (180) provided between the first and second electromagnets and having a plate-shaped portion (182) facing the attracting surface of the first electromagnet; and a second thread pressing plate (192) provided between the first and second electromagnets and closer to the second electromagnet than the first thread pressing plate and having a plate-shaped portion ( 192 ) facing the attracting surface of the second electromagnet. and a second thread pressing plate (190) having a second thread tensioner (110) and a second thread tensioner (112) having a second thread tensioner (114) and a second thread tensioner (116) and a second thread tensioner (118 ... When the value of the magnetic force of the first electromagnet and the second electromagnet becomes smaller than a predetermined value, the first electromagnet and the second electromagnet are excited to attract each other, thereby clamping the upper thread between the plate-shaped portion of the first thread presser disc and the plate-shaped portion of the second thread presser disc, and tension is applied to the upper thread. On the other hand, when the state in which the thread take-up pulls the upper thread is released, the thread locking unit rotates to shorten the distance between the magnet portion and the magnetic sensor, and the value of the magnetic force of the magnet portion detected by the magnetic sensor becomes equal to or greater than a predetermined value, the excitation of the first electromagnet and the second electromagnet is stopped to release the attraction between the first electromagnet and the second electromagnet, thereby releasing the application of tension to the upper thread.

Therefore, when applying tension to the yarn, it is sufficient to excite the first and second electromagnets so that they are attracted to each other. In particular, by simultaneously exciting the first and second electromagnets, the first and second electromagnets can be attracted to each other quickly, allowing for a high-speed response in applying tension.

In addition, when cutting off the application of yarn tension, the supply of current to the first electromagnet and the second electromagnet can be stopped, without reverse exciting the electromagnets. In addition, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, the excitation of the first electromagnet and the second electromagnet can be quickly cut off, allowing for a high-speed response when cutting off tension.

In addition, when no tension is applied to the thread, the current supply to the first and second electromagnets can be stopped, and there is no need to continue to reverse-excite the electromagnets. This makes it possible to suppress heat generation in the first and second electromagnets and to reduce the size of the first and second electromagnets.

In addition, since the thread tension is applied by two electromagnets, a large thread tension can be applied, and as a result, a wide range of thread tension can be applied, from no thread tension to a large thread tension.

In addition, the first and second electromagnets are controlled according to the detection results of the magnetic sensor based on the behavior of the thread locking unit in the thread take-up spring mechanism, and are not related to other control signals in the control unit of the sewing machine, making it easy to install on existing sewing machines.

Furthermore, the fixing unit has a plate-shaped portion extending toward the thread tension applying portion, the electromagnet holder unit is provided on the plate-shaped portion, and the thread take-up spring mechanism and the thread tension applying portion are integrally formed, so that when attaching the thread tension control device to the sewing machine, there is no need to adjust the positional relationship between the thread take-up spring mechanism and the thread tension applying portion.

Thirdly, in the first or second configuration, the thread tension control device for a sewing machine is provided with a memory device (318) that stores current data that stores the current value when exciting the first electromagnet and the second electromagnet for each stitch, and the control unit excites the first electromagnet and the second electromagnet in accordance with the current value stored in the current data when exciting the first electromagnet and the second electromagnet in each stitch.

Therefore, by providing current data, the current value when exciting the first electromagnet and the second electromagnet for each stitch can be adjusted, thereby controlling the upper thread tension for each stitch.

Fourthly, in the first or second configuration, the fixed unit has a central component (41), a tip portion (72) attached to the central component, and a guide wall portion (30). The central component is a thread take-up spring mounting portion for mounting the thread take-up spring, the thread take-up spring mounting portion (42) having a cylindrical circumferential surface, and a shaft portion (46) provided on the back side of the thread take-up spring mounting portion, the shaft portion having a cylindrical circumferential surface and an outer diameter smaller than the outer diameter of the thread take-up spring mounting portion. The guide wall portion is provided on the back side of the shaft portion, has an annular protrusion (34) protruding toward the thread take-up spring mounting portion and has an outer diameter larger than the outer diameter of the shaft portion. the thread take-up spring is formed from a linear member ; a fixing portion of the thread take-up spring is fixed to the peripheral surface of the thread take-up spring mounting portion; the thread locking unit has a protrusion (54) connected to the fixing portion and protruding from the peripheral surface of the thread take-up spring mounting portion; the thread locking portion is connected to the tip of the protrusion; the magnet portion is attached to the protrusion; the magnetic sensor is provided in the end area on the rear side of the cover portion; and the upper thread guided from the thread tension applying portion comes into contact with the peripheral surface of the shaft portion and then locks with the thread locking portion.

The shaft is sandwiched between the thread take-up spring device and the guide wall, and the thread take-up spring mounting section and the guide wall 30 are also formed with small diameters, making it easier to bring the upper thread into contact with the circumferential surface of the shaft. In addition, by bringing the upper thread in contact with the circumferential surface of the shaft into contact with the guide wall, the position of the upper thread in the front-to-rear direction can be stabilized, and since the annular protrusion of the guide wall protrudes toward the thread take-up spring mounting section, the upper thread can be smoothly transferred even if it comes into contact with the guide wall.

In addition, the fifth aspect is that, in the first or second configuration, the electromagnet holder unit has a first connecting member (134) that connects the first electromagnet holder and the second electromagnet holder and has a cylindrical outer peripheral surface, and a second connecting member (136) that connects the first electromagnet holder and the second electromagnet holder and has a cylindrical outer peripheral surface, the first connecting member and the second connecting member are provided with the axis of the cylindrical outer peripheral surface in the left-right direction, the first connecting member is provided on the back part of the electromagnet holder unit, and the second connecting member is provided on the front part of the electromagnet holder unit, the first connecting member and the second connecting member are provided in positions facing each other through the first thread pressing plate and the second thread pressing plate, and the upper thread path of the upper thread led from the upstream of the thread tension applying part returns to the first connecting member after reaching the second connecting member from the first connecting member, and then reaches the thread take-up spring mechanism part.

Therefore, by using two connecting members, the first connecting member and the second connecting member, an upper thread path can be provided between the first thread pressing plate and the second thread pressing plate. In particular, since the upper thread path passes from the first connecting member to the second connecting member and then returns to the first connecting member, two upper thread paths can be provided between the first thread pressing plate and the second thread pressing plate, and tension can be efficiently applied to the upper thread.

Also, as a configuration 5-1, in the above-mentioned configuration 5, the first connecting member may be provided on the top surface side of the back portion of the electromagnet holder unit, and the second connecting member may be provided on the bottom surface side of the front portion of the electromagnet holder unit.

Furthermore, the sixth feature is that in the first or second configuration, the target storage section, which is one of the two storage sections, the first storage section and the second storage section, is provided with a biasing means (200) for biasing an electromagnet, which is either the first electromagnet or the second electromagnet, stored in the target storage section toward the opening side of the target storage section.

Therefore, even when the first electromagnet and the second electromagnet are not excited, the plate-shaped portion of the first thread presser plate and the plate-shaped portion of the second thread presser plate are in contact with each other, and the first thread presser plate is in contact with the first electromagnet, and the second thread presser plate is in contact with the second electromagnet. Therefore, when the first electromagnet and the second electromagnet are excited, tension can be applied to the upper thread instantly, and the response of tension application can be made faster.

In addition, as the configuration 6-1, in the configuration 4, the central component is a second shaft portion connected to the rear side from the rear end of the shaft portion, the second shaft portion (48) having an outer diameter smaller than the outer diameter of the shaft portion and a screw groove formed on the circumferential surface, the guide wall portion is provided with a through hole (31) through which the second shaft portion is inserted and has an outer diameter smaller than the outer diameter of the shaft portion, the thread take-up spring mechanism portion is a plate-shaped mounting plate portion (20) provided with a through hole (21) through which the second shaft portion is inserted, and a housing of the sewing machine and an insertion locking portion (10) having a screw hole into which the second shaft portion is screwed, the insertion locking portion being inserted into a hole for insertion locking provided in the guide wall portion and locked, the insertion locking portion being provided with a screw hole into which the second shaft portion is screwed, and the mounting plate portion is provided on the rear side of the guide wall portion, the insertion locking portion being provided on the rear side of the mounting plate portion, and the second shaft portion is screwed into the screw hole of the insertion locking portion while being inserted into the through hole of the guide wall portion and the through hole of the mounting plate portion, and the guide wall portion and the mounting plate portion are fixed between the shaft portion and the insertion locking portion.

In addition, as a configuration of No. 6-2, in the configuration of No. 6-1, the central component has a third shaft portion (44) connected to the front end of the thread take-up spring mounting portion, and the tip portion is a cylindrical portion protruding from the front of the cover portion (79) and has a cylindrical portion (76) having a hole portion (73) into which the third shaft portion is inserted, and the tip portion is fixed to the central component by fixing the cylindrical portion to the third shaft portion with the third shaft portion inserted into the hole, and the cover portion has a second cylindrical portion (74) connected to the cylindrical portion and having an outer diameter larger than that of the cylindrical portion, and a magnetic sensor attachment portion (78) provided on the outer circumferential surface of the second cylindrical portion and protruding to the rear side, and the magnetic sensor is attached to the magnetic sensor attachment portion.

The seventh item is a thread tension applying device for a sewing machine provided upstream of a thread take-up in an upper thread path, comprising an electromagnet holder unit having a first electromagnet holder (120) having a first storage section (132) for storing a first electromagnet, and a second electromagnet holder (140) having a second storage section (152) for storing a second electromagnet, the first electromagnet holder and the second electromagnet holder being provided at a distance from each other, an opening (132K) being provided on the second electromagnet holder side of the first storage section, and an opening (152K) being provided on the first electromagnet holder side of the second storage section, the electromagnet holder unit (119) having two openings facing each other, and a first electromagnet having an attraction surface (162a) on the second electromagnet side, the second electromagnet holder side of the first storage section being on the left side, and the second electromagnet holder side of the second storage section being on the right side. When the first electromagnet holder side is on the right side, the device has a first electromagnet (160) stored in the first storage section so as to be movable in the left-right direction, a second electromagnet (170) having an attraction surface (172a) on the first electromagnet side and stored in the second storage section so as to be movable in the left-right direction, a first thread pressing plate (180) provided between the first and second electromagnets, and a second thread pressing plate (190) provided between the first and second electromagnets, closer to the second electromagnet than the first thread pressing plate, and facing the first thread pressing plate. An upper thread path is provided between the first and second thread pressing plates, and the first and second electromagnets are excited to attract the first and second electromagnets, thereby clamping the upper thread between the first and second thread pressing plates and applying tension to the upper thread.

Therefore, when applying tension to the yarn, it is sufficient to excite the first and second electromagnets so that they are attracted to each other. In particular, by simultaneously exciting the first and second electromagnets, the first and second electromagnets can be attracted to each other quickly, allowing for a high-speed response in applying tension.

In addition, when cutting off the application of yarn tension, the supply of current to the first electromagnet and the second electromagnet can be stopped, without reverse exciting the electromagnets. In addition, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, the excitation of the first electromagnet and the second electromagnet can be quickly cut off, allowing for a high-speed response when cutting off tension.

In addition, when no tension is applied to the thread, the current supply to the first and second electromagnets can be stopped, and there is no need to continue to reverse-excite the electromagnets. This makes it possible to suppress heat generation in the first and second electromagnets and to reduce the size of the first and second electromagnets.

In addition, since the thread tension is applied by two electromagnets, a large thread tension can be applied, and as a result, a wide range of thread tension can be applied, from no thread tension to a large thread tension.

In the eighth aspect, in the seventh aspect, the thread tensioning device for a sewing machine has a first connecting member (134) that connects the first electromagnet holder and the second electromagnet holder and has a cylindrical outer circumferential surface, and a second connecting member (136) that connects the first electromagnet holder and the second electromagnet holder and has a cylindrical outer circumferential surface, the first connecting member and the second connecting member are provided with the axis of the cylindrical outer circumferential surface in the left-right direction, the first connecting member is provided on the back part of the electromagnet holder unit, and the second connecting member is provided on the front part of the electromagnet holder unit, the first connecting member and the second connecting member are provided in positions facing each other through the first thread pressing plate and the second thread pressing plate, and the upper thread path of the upper thread led from the upstream of the thread tensioning part reaches the second connecting member from the first connecting member, returns to the first connecting member, and then reaches the thread take-up spring mechanism.

Therefore, by using two connecting members, the first connecting member and the second connecting member, an upper thread path can be provided between the first thread pressing plate and the second thread pressing plate. In particular, since the upper thread path passes from the first connecting member to the second connecting member and then returns to the first connecting member, two upper thread paths can be provided between the first thread pressing plate and the second thread pressing plate, and tension can be efficiently applied to the upper thread.

In addition, the ninth aspect is characterized in that in the seventh or eighth configuration, the target storage section, which is one of the two storage sections, the first storage section and the second storage section, is provided with a biasing means (200) that biases an electromagnet, which is either the first electromagnet or the second electromagnet, stored in the target storage section toward the opening side of the target storage section.

Therefore, even when the first electromagnet and the second electromagnet are not excited, the plate-shaped portion of the first thread presser plate and the plate-shaped portion of the second thread presser plate are in contact with each other, and the first thread presser plate is in contact with the first electromagnet, and the second thread presser plate is in contact with the second electromagnet. Therefore, when the first electromagnet and the second electromagnet are excited, tension can be applied to the upper thread instantly, and the response of tension application can be made faster.

According to the sewing machine thread tension control device and sewing machine thread tension applying device based on the present invention, when applying thread tension, it is sufficient to excite the first electromagnet and the second electromagnet so that they are attracted to each other. In particular, by exciting the first electromagnet and the second electromagnet simultaneously, the first electromagnet and the second electromagnet can be attracted to each other quickly, so that the response to applying tension can be performed quickly.

In addition, when cutting off the application of yarn tension, the supply of current to the first electromagnet and the second electromagnet can be stopped, without reverse exciting the electromagnets. In addition, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, the excitation of the first electromagnet and the second electromagnet can be quickly cut off, allowing for a high-speed response when cutting off tension.

In addition, when no tension is applied to the thread, the current supply to the first and second electromagnets can be stopped, and there is no need to continue to reverse-excite the electromagnets. This makes it possible to suppress heat generation in the first and second electromagnets and to reduce the size of the first and second electromagnets.

In addition, since the thread tension is applied by two electromagnets, a large thread tension can be applied, and as a result, a wide range of thread tension can be applied, from no thread tension to a large thread tension.

In addition, the thread tension control device for a sewing machine based on the present invention controls the first electromagnet and the second electromagnet in response to the detection results of the magnetic sensor based on the behavior of the thread locking unit in the thread take-up spring mechanism, and is not related to other control signals in the control unit of the sewing machine, making it easy to install on existing sewing machines.

FIG. 2 is a perspective view showing a thread tension control device and a state in which the thread tension control device is attached to a sewing machine. FIG. FIG. FIG. 4 is a cross-sectional view of a main part of the thread take-up spring mechanism. FIG. FIG. 4 is a perspective view of the thread tension imparting portion as seen from the left side. FIG. 4 is a perspective view of the thread tension imparting portion as seen from the right side. FIG. 2 is a side view showing a state in which the yarn tension control device is used. FIG. 4 is a cross-sectional view showing a state in which the thread tension imparting portion is used. FIG. 2 is a front view showing a state in which the yarn tension control device is used. FIG. 2 is an explanatory diagram showing a configuration of a sewing machine. FIG. 2 is an explanatory diagram illustrating a configuration of embroidery data. FIG. 4 is an explanatory diagram showing a configuration of current data. FIG. 4 is an explanatory diagram showing a configuration of spindle data; FIG. 4 is a flowchart showing the operation of the yarn tension control device. FIG. 4 is a front view showing a yarn tension control device of a first modified example. FIG. 4 is a perspective view showing a yarn tension control device of a first modified example. FIG. 4 is an exploded perspective view showing a yarn tension control device of a first modified example. FIG. 13 is a front view showing a yarn tension control device of a second modified example. FIG. 13 is a front view showing a yarn tension control device of a third modified example.

The present invention provides an upper thread tension control device that can apply upper thread tension by detecting the displacement of the thread take-up spring, and that can respond quickly to tension application and can cut off thread tension application without continuously reverse-exciting the electromagnet.The objective of the present invention is achieved as follows.

The thread tension control device 1 for a sewing machine based on the present invention is configured as shown in Figures 1 to 16, and has a thread take-up spring mechanism 5, a thread tension applying unit 105, and a control circuit 316, and the thread take-up spring mechanism 5 is provided below the thread tension applying unit 105.

The thread take-up spring mechanism 5 is configured as shown in Figures 1 to 4, 8 and 10, and has an insertion locking portion 10 for insertion and attachment into the housing portion 302 of the arm portion 301 of the sewing machine 300, a plate-shaped mounting plate portion 20 provided on the front side of the insertion locking portion 10, a guide wall portion 30 attached to the front side of the mounting plate portion 20, the insertion locking portion 10, the mounting plate portion 20, the guide wall portion 30, a central component unit 40 that is inserted into the tip unit 70 and forms the center of the thread take-up spring mechanism 5, a thread take-up spring unit 50 fixedly attached to the central component unit 40, a tip unit 70 that forms the front tip of the thread take-up spring mechanism 5, and a magnetic sensor (which may be a magnetic force sensor) 80 provided in the tip unit 70. The insertion locking portion 10, the mounting plate portion 20, the guide wall portion 30, the central component portion 41 in the central component unit, and the tip unit 70 constitute a fixed unit 9 that is removably fixed to the sewing machine.

Here, the insertion locking part 10 has a substantially circular tubular shape, and includes a cylindrical tubular part 12, an annular part 14 provided on the front side of the tubular part 12, and a locking part 16 provided on the back side of the tubular part 12. The annular part 14 has a plate-like ring shape, and the locking part 16 has a shape in which both ends of the plate-like ring are cut off, and is plate-like surrounded by opposing arc-shaped sides and parallel straight sides. The diameter of the annular part 14 and the diameter of the arc-shaped sides of the locking part 16 are formed larger than the diameter of the tubular part 12. The insertion locking part 10 is inserted into a mounting hole 302a (see FIG. 8) provided in the housing part 302, and then rotated, so that the locking part 16 locks into the mounting hole 302a, and the thread take-up spring mechanism part 5 is attached to the housing part 302.

This insertion locking portion 10 has a screw hole 11 extending from the front end to the rear end, and this screw hole 11 is adapted to screw into the shaft portion 48 of the central component 41 (described below).

The mounting plate 20 is in the form of a plate with a circular outer shape, with flat front and rear surfaces, and a circular through hole 21 in the center, with a diameter that is approximately the same as the diameter of the shaft 48, allowing the shaft 48 to be inserted through the through hole 21. The diameter of the mounting plate 20 is larger than the diameter of the annular portion 14. When the thread take-up spring mechanism 5 is attached to the housing 302, the rear surface of the mounting plate 20 is attached in contact with the housing 302.

The guide wall 30 has an annular convex shape and protrudes circumferentially toward the front side (i.e., toward the thread take-up spring mounting portion 42). That is, the guide wall 30 has a central portion 32 having an annular plate shape and an annular convex portion 34 connected to the outer circumferential end of the central portion 32. The annular convex portion 34 has an inner inclined portion 35 connected to the outer circumferential end of the central portion 32 and having a cylindrical shape with a larger diameter toward the front side, a convex surface portion 36 connected to the end of the inner inclined portion 35 opposite the central portion 32 and having a ring plate shape, and an outer inclined portion 37 connected to the outer circumferential end of the convex surface portion 36 and having a cylindrical shape with a larger diameter toward the back side. The guide wall 30 is provided on the back side of the shaft portion 46 and has an outer diameter (diameter) larger than the outer diameter (diameter) of the shaft portion 46.

A through hole 31 is provided in the center of the central portion 32, and the inner inclined portion 35 and the outer inclined portion 37 are approximately truncated cones. The front surface of the convex portion 36 is perpendicular to the axis P (see Figure 3).

This guide wall portion 30 is a member that comes into contact with the upper thread J that is guided in contact with the peripheral surface of the shaft portion 46 (described later). By keeping the upper thread in contact with the guide wall portion 30, the position of the upper thread in the front-to-rear direction (the Y1-Y2 direction (the direction of the axis P) in FIG. 3, the left-to-right direction in FIG. 4) can be stabilized. In particular, as shown in FIG. 8, after the upper thread guided from the thread tension applying portion 105 comes into contact with the shaft portion 46 at approximately the center position of the shaft portion 46 in the front-to-rear direction, the engagement position with the guide member 304 is adjusted to the position where the upper thread is engaged with the shaft portion 46. By positioning the upper thread as close to the guide wall 30 as possible when it is in contact with the shaft 46, the position of the upper thread in the front-to-rear direction in the thread take-up spring mechanism 5 can be stabilized. Also, as shown in FIG. 4, the annular protrusion 34 of the guide wall 30 protrudes to approximately the center of the shaft 46 in the front-to-rear direction (left-to-right direction in FIG. 4), so the upper thread can be positioned as approximately in the center of the shaft 46 in the front-to-rear direction as possible.

Note that FIG. 4 is a cross-sectional view of the essential parts, focusing on components other than the magnetic sensor mounting portion 78 and the magnetic sensor 80.

When the upper thread J comes into contact with the guide wall 30, it comes into contact with the convex surface 36. However, since the convex surface 36 is provided at the end of the front side of the annular convex portion 34 and the area of the convex surface 36 is small, the area with which the upper thread J comes into contact is also small, and even if the upper thread J comes into contact with the guide wall 30, the upper thread J can be smoothly transferred to the balance 306 side.

The diameter of the through hole 31 is approximately the same as the diameter of the shaft portion 48, so that the shaft portion 48 can be inserted into the through hole 31.

The central component unit 40 also has a central component part 41 that is generally axially shaped, and a thread take-up spring unit 50 that is fixed to the central component part 41.

The central component 41 has a cylindrical thread take-up spring mounting part 42, a shaft part 44 connected to the front surface of the thread take-up spring mounting part 42, a shaft part 46 connected to the rear surface of the thread take-up spring mounting part 42, and a shaft part 48 connected to the rear surface of the shaft part 46.

The thread take-up spring attachment part 42 is cylindrical, with the front and back surfaces formed as flat surfaces. In other words, the thread take-up spring attachment part 42 has a cylindrical peripheral surface.

The shaft portion (third shaft portion) 44 is cylindrical (i.e., has a cylindrical peripheral surface), and the diameter of the shaft portion 44 is smaller than the outer diameter (diameter) of the thread take-up spring mounting portion 42 and the outer diameter (diameter) of the shaft portion 46.

The shaft 46 is cylindrical (i.e., has a cylindrical circumferential surface), and the outer diameter of the shaft 46 is smaller than the outer diameter of the thread take-up spring attachment part 42, smaller than the outer diameter (diameter) of the central part 32, and larger than the through-hole 31. In other words, when the thread take-up spring mechanism part 5 is assembled, the rear surface of the shaft 46 is in contact with the front surface of the central part 32.

The length of the shaft 46 in the axial direction (front-rear direction) (Y1-Y2 direction (direction of axis P) in FIG. 3) is longer than the length of the inner inclined portion 35 in the axial direction, so that a gap W (see FIG. 8) is provided in the axial direction between the rear end of the thread take-up spring mounting portion 42 and the convex portion 36 of the guide wall portion 30.

The shaft portion 46 is sandwiched between the thread take-up spring mounting portion 42 and the guide wall portion 30, and is formed with a smaller diameter than the thread take-up spring mounting portion 42 and the guide wall portion 30, so that the upper thread can be easily brought into contact with the circumferential surface of the shaft portion 46. In other words, the position where the shaft portion 46 is in contact with the circumferential surface becomes the upper thread path.

The shaft portion (second shaft portion) 48 is generally cylindrical, with the tip on the rear side of the cylinder tapered (i.e., truncated cone). In other words, the diameter of the shaft portion 48 is smaller than the diameter of the shaft portion 46, and a screw groove is formed on the cylindrical circumferential surface of the shaft portion 48.

When the shaft portion 48 is screwed into the insertion locking portion 10 and tightened, the mounting plate portion 20 and the guide wall portion 30 are sandwiched and fixed between the shaft portion 46 and the insertion locking portion 10.

The axis of the thread take-up spring mounting portion 42 and the axis of the shaft portions 44, 46, and 48 are aligned.

The thread take-up spring unit 50 also has a thread take-up spring 51 formed from a linear member and a magnet portion 64 attached to the thread take-up spring 51.

The thread take-up spring 51 has a winding portion 52 that is wound around the thread take-up spring mounting portion 42 and fixed to the thread take-up spring mounting portion 42, a protrusion 54 that is connected to the end of the winding portion 52, and a thread locking portion 56 that is connected to the tip of the protrusion 54. The thread locking portion 56 and the protrusion 54 form a thread locking unit 57.

The winding part 52 is wound circumferentially around the outer periphery of the thread take-up spring mounting part 42, and the end of the winding part 52 (the end opposite the protruding part 54) is fixed to the thread take-up spring mounting part 42. In other words, the winding part 52 is fixed to the periphery of the thread take-up spring mounting part 42 by inserting the end into a hole provided on the surface of the thread take-up spring mounting part 42. The winding part 52 corresponds to the fixed part fixed to the fixing unit 9.

The protrusion 54 is bent from the end of the winding section 52 and is generally linear, and is formed to protrude from the outer circumferential surface of the thread take-up spring attachment section 42 so as to move away from the outer circumferential surface as it moves from the base end, which is the winding section 52 side, to the tip end, which is the thread locking section 56 side.

The thread locking portion 56 has a base end 58 formed by bending at a substantially right angle from the tip of the protruding portion 54, an intermediate portion 60 connected to the tip of the base end 58, and a tip end 62 connected to the tip of the intermediate portion 60, and the base end 58 and tip end 62 are substantially linear, while the intermediate portion 60 is substantially arc-shaped. In other words, the thread locking portion 56 is substantially U-shaped overall, and the base end 58 and tip end 62 are substantially parallel with a gap between them. The base end 58 and tip end 62 are arranged on the same imaginary plane, but the imaginary plane is parallel to the axis P, and the direction of the base end 58 and tip end 62 is substantially perpendicular to the axis P.

The axial position of the thread locking portion 56 is a position where the range of the spacing W is included in the range of the spacing U (see FIG. 8) between the base end 58 and the tip end 62, and preferably, the midpoint of the spacing W in the axial direction (a position equidistant from one end and the other end in the range of the spacing W) is approximately the same as the midpoint of the spacing U in the axial direction (a position equidistant from one end and the other end in the range of the spacing U).

The upper thread J passes through the inside of the thread retaining portion 56, and when the upper thread J is pulled by the thread take-up lever 306, the upper thread J is retained by the intermediate portion 60, and the thread retaining unit 57 rotates relative to the winding portion 52.

The magnet section 64 is a tubular (specifically, cylindrical) permanent magnet with a through hole in the center, and the magnet section 64 is fixed to the protrusion 54 with the protrusion 54 inserted through the through hole. The direction of magnetization is arbitrary as long as the magnetic sensor 80 can detect magnetism, but for example, one side is the north pole and the other is the south pole through a boundary surface perpendicular to the axis of the through hole. In other words, one side is the north pole and the other is the south pole through the center in the axial direction of the through hole. In that case, the positions of the north and south poles may be such that the north pole is at the tip side of the protrusion 54, or the south pole is at the tip side of the protrusion 54.

The tip unit 70 has a cylindrical tip portion 72, a screw 77, and a magnetic sensor attachment portion 78 provided on the outer peripheral surface of the tip portion 72.

The tip portion 72 has a cylindrical tubular portion 74, a tip wall portion 75 provided on the front side of the tubular portion 74, and a cylindrical tubular portion 76 formed to protrude from the tip wall portion 75 to the front side, and a through hole 73 is provided in the tip wall portion 75 and the tubular portion 76. The diameter of the through hole 73 is approximately the same as the diameter of the shaft portion 44, so that the shaft portion 44 can be inserted into the through hole 73. In addition, the outer diameter of the tubular portion 76 is formed to be smaller than the outer diameter of the tubular portion 74.

The inner diameter of the cylindrical portion 74 is larger than the outer diameter of the thread take-up spring mounting portion 42, and is sized to accommodate the thread take-up spring mounting portion 42 with the winding portion 52 attached. When the tip unit 70 is attached to the central configuration unit 40, as shown in FIG. 4, a gap is formed between the inner surface of the cylindrical portion 74 and the outer surface of the thread take-up spring mounting portion 42.

The cylindrical portion 76 also has a screw hole 76a formed perpendicular to the axial direction for screwing in a screw 77. With the shaft portion 44 inserted into the through hole 73, the screw 77 is screwed into the screw hole 76a, and the tip of the screw 77 presses the shaft portion 44, thereby fixing the tip unit 70 to the shaft portion 44.

The magnetic sensor mounting portion 78 has a generally rectangular parallelepiped shape and is fixed to the outer peripheral surface of the cylindrical portion 74, with the magnetic sensor mounting portion 78 protruding further toward the rear side than the end portion on the rear side of the cylindrical portion 74. In other words, the magnetic sensor 80 is fixed to the side of the magnetic sensor mounting portion 78, but the magnetic sensor mounting portion 78 protrudes further toward the rear side than the end portion on the rear side of the cylindrical portion 74 so that the magnetic sensor 80 faces the magnet portion 64 at a position close to the magnet portion 64.

The cylindrical portion 74 and the magnetic sensor attachment portion 78 constitute a "cover portion 79 having an inner peripheral surface with an inner diameter larger than the outer diameter of the thread take-up spring attachment portion and having a generally cylindrical shape." As shown in FIG. 4, the cover portion 79 covers the outside of the thread take-up spring attachment portion 42 except for the rear end region of the thread take-up spring attachment portion 42, and the central component portion 41 is provided inside the inner peripheral surface of the cover portion 79. To ensure space for the winding portion 52, a gap is provided between the inner peripheral surface of the cover portion 79 and the outer peripheral surface of the thread take-up spring attachment portion 42.

The magnetic sensor 80 is fixed to the side of the magnetic sensor attachment section 78, specifically, in the end area on the rear side of the side of the magnetic sensor attachment section 78 (i.e., the area protruding from the rear end of the cylindrical section 74 of the magnetic sensor attachment section 78 to the rear side). As a result, when the tip unit 70 is attached to the central component section 41, as shown in Figures 4 and 8, the axial position (direction of axis P) of the magnetic sensor 80 and the axial position (direction of axis P) of the magnet section 64 are approximately the same, and the magnet section 64 is in close proximity to the magnetic sensor 80. In other words, when the thread locking unit 57 is not rotating relative to the winding section 52, the magnetic sensor 80 is provided facing the magnet section 64. In addition, the protrusion 54 and thread locking portion 56 of the thread take-up spring unit 50 are located on the rear side of the rear end of the tubular portion 74, so the tubular portion 74 does not get in the way when the thread locking unit 57 consisting of the protrusion 54 and the thread locking portion 56 rotates. Also, since the magnet portion 64 is located outside (farther from the axis P) than the imaginary extension plane of the outer circumferential surface of the tubular portion 74, the tubular portion 74 does not get in the way when the magnet portion 64 rotates together with the thread locking unit 57.

The cover portion 79 is composed of the cylindrical portion 74 and the magnetic sensor mounting portion 78, and the magnetic sensor 80 is provided in the end area on the rear side of the side surface of the magnetic sensor mounting portion 78. Therefore, it can be said that the magnetic sensor 80 is provided in the end area on the rear side of the cover portion 79.

When the thread take-up spring mechanism 5 is assembled, the shaft 48 is screwed into the screw hole 11 of the insertion lock 10 and tightened, thereby fixing the insertion lock 10 to the shaft 48, and the guide wall 30 and the mounting plate 20 are pressed against the insertion lock 10 by the shaft 46 and fixed. Furthermore, the tip unit 70 is fixed to the shaft 44 by inserting the shaft 44 into the through hole 73 and fixing it with a screw 77.

As described above, the fixed unit 9 is composed of the insertion locking portion 10, the mounting plate portion 20, the guide wall portion 30, the central component portion 41 in the central component unit, and the tip unit 70, so the thread take-up spring 51 and the magnetic sensor 80 can be said to be provided in the fixed unit.

The thread take-up spring mechanism 5 is configured as described above, and the upper thread J conveyed from the thread tension applying unit 105 comes into contact with the lower part of the circumferential surface of the shaft 46 from the right side (X2 side) of the shaft 46, and then is engaged with the thread locking unit 56 before reaching the balance 306 via the guide member 304. When the balance 306 rises and pulls the upper thread J, the thread locking unit 56 rotates downward, and the downward rotation of the thread locking unit 56 also rotates the protrusion 54 (i.e., the entire thread locking unit 57 rotates), causing the magnet unit 64 to move away from the magnetic sensor 80. When the magnet unit 64 moves away from the magnetic sensor 80, the magnetic force detected by the magnetic sensor 80 weakens.

The components constituting the thread take-up spring mechanism 5 (specifically, the insertion locking portion 10, the mounting plate portion 20, the guide wall portion 30, the central component portion 41, the tip unit 70 (tip portion 72, the magnetic sensor mounting portion 78, etc.)) are made of a non-magnetic material. In other words, the components constituting the thread take-up spring mechanism 5 are made of a non-magnetic material so that when the magnet portion 64 is attracted to the magnetic material and an external force is applied to the magnet portion 64, the upper thread J is locked to the thread locking portion 56, and the thread locking portion 56 does not become an obstacle when it rotates. Examples of non-magnetic materials include aluminum and stainless steel, and synthetic resin may be used as long as the strength is not a problem.

Next, the thread tension applying section (thread tension applying device for a sewing machine) 105 is configured as shown in Figures 1, 5 to 10, and has an attachment plate section 110 for attachment to the housing section 302 of the arm section 301 of the sewing machine 300, an electromagnet holder 120 for storing the electromagnet 160, a rod-shaped member (first connecting member) 134, a tubular member (second connecting member) 136, an electromagnet holder 140 for storing the electromagnet 170, the electromagnet 160, the electromagnet 170, thread pressing plates 180, 190 provided between the electromagnet 160 and the electromagnet 170, a spring 200 provided between the electromagnet 170 and the electromagnet holder 140, and an upper thread guide section 210. The electromagnet holder 120, the rod-shaped member 134, the cylindrical member 136, the electromagnet holder 140, and the screws 137 and 154 (described below) form the electromagnet holder unit 119.

The mounting plate (fixing member) 110 is in the form of a vertically elongated rectangular plate, and the upper region of the mounting plate 110 is provided with an insertion hole 110a for inserting a screw for attaching the upper thread guide 210 to the housing 302, and a screw hole 110b for screwing in a screw for attaching the upper thread guide 210, the lower region is provided with an insertion hole 110c for inserting a screw for attaching the housing 302, and further, a screw hole 110d for inserting a screw for attaching the electromagnet holder 120 is provided in the intermediate region between the upper and lower regions.

The electromagnet holder (first electromagnet holder) 120 is a holder in which a storage section (first storage section) 132 for storing the electromagnet 160 is open on the left side (X1 side), and has a holder main body 121. The holder main body 121 has an upper surface section 122, a front surface section 124 connected downward from an end portion of the front side (Y1 side) of the upper surface section 122, a back surface section 126 connected downward from an end portion of the back side (Y2 side) of the upper surface section 122, an end portion of the right side side (X2 side) of the upper surface section 122, and an end portion of the right side side of the front surface section 124. It has a right side portion 128 connected to the end portion on the right side of the back portion 126, and a bottom portion 130 connected to the lower end portion of the front portion 124, the lower end portion of the back portion 126, and the lower end portion of the right side portion 128. The right side surface of the top portion 122, the right side surface of the right side portion 128, and the right side surface of the bottom portion 130 form a single plane, and the left side surface of the top portion 122, the left side surface of the front portion 124, the left side surface of the back portion 126, and the left side surface of the bottom portion 130 form a single plane.

The bottom surface 130 has a notch 129 formed in a strip shape from the end on the left side surface to the right side surface, and a storage section 132 is provided above the notch 129.

The storage section 132 is a storage section in which the end area on the opening 132K side is formed with a larger diameter than other areas, and has a storage section main body 132-1 and a large diameter section 132-2 formed with a larger diameter than the storage section main body 132-1.

The storage unit main body 132-1 is a space surrounded by an inner peripheral surface 132a along the cylindrical periphery and a flat surface 132b on the right side surface that is connected to the inner peripheral surface 132a, and the diameter of the inner peripheral surface 132a is formed to be larger than the outer diameter of the electromagnet 160 and smaller than the outer diameter of the thread pressing plate 180 so that the electromagnet 160 can be stored therein. When the thread tension applying unit 105 is assembled, the electromagnet 160 is stored in the storage unit main body 132-1.

The large diameter section 132-2 is a space surrounded by an inner circumferential surface 132c along the cylindrical circumferential surface and an annular flat surface 132d connected to the inner circumferential surface 132c, and the diameter of the inner circumferential surface 132c is formed to be larger than the outer diameter of the thread presser plate 180 so that the thread presser plate 180 can be accommodated therein. When the thread tension applying section 105 is assembled, the thread presser plate 180 is placed in the large diameter section 132-2. The flat surface 132d is also connected to the inner circumferential surface 132a.

The axial length (direction of axis Q) of the storage section 132 (the sum of the axial length of the inner circumferential surface 132a and the axial length of the inner circumferential surface 132c) is approximately the same as the axial length of the electromagnet 160, but may be longer than the axial length of the electromagnet 160.

The axial length of the large diameter portion 132-2 (the length of the inner peripheral surface 132c) is approximately the same as the thickness of the thread pressing plate 180 or is longer than the thickness of the thread pressing plate 180.

A pair of walls 129a, 129b that form the cutout 129 are connected to the lower ends of the inner circumferential surfaces 132a, 132c, and a flat surface 132b is connected to the right side ends of the walls 129a, 129b. The center lines of the inner circumferential surfaces 132a, 132c face in the direction of the axis Q (left-right direction (X1-X2 direction)). The storage section 132 has an opening 132K on the electromagnet holder 140 side.

A through hole 125 for inserting a cylindrical member 136 is provided at the bottom side (Z1 side) end portion of the front part 124 of the electromagnet holder 120, and a through hole 127 for inserting a rod-shaped member 134 is provided at the rear side end portion of the top part 122. A screw hole for screwing a screw 137 is provided between the lower surface of the bottom part 130 and the through hole 125.

The rod-shaped member 134 is a rod-shaped member having a cylindrical outer circumferential surface, and connects the electromagnet holder 120 and the electromagnet holder 140. The rod-shaped member 134 is provided with the axis of the cylindrical outer circumferential surface in the left-right direction. The rod-shaped member 134 is provided on the upper surface side (Z2 side) of the back portion of the electromagnet holders 120 and 140.

The cylindrical member 136 is a cylindrical member having a cylindrical outer peripheral surface, and connects the electromagnet holder 120 and the electromagnet holder 140. The cylindrical member 136 is provided with the axis of the cylindrical outer peripheral surface in the left-right direction. The cylindrical member 136 is provided on the bottom side of the front portion of the electromagnet holders 120 and 140. The wiring of the electromagnet 170 is inserted into the cylindrical member 136.

In other words, the rod-shaped member 134 and the tubular member 136 are provided in positions that face each other via the thread pressing plates 180, 190. Note that, although it has been stated that the rod-shaped member 134 is provided on the upper surface side of the back portion of the electromagnet holders 120, 140 and the tubular member 136 is provided on the bottom surface side of the front portion of the electromagnet holders 120, 140, it is sufficient that the rod-shaped member 134 is provided on the back portion of the electromagnet holders 120, 140 and the tubular member 136 is provided on the front portion of the electromagnet holders 120, 140, and that the rod-shaped member 134 and the tubular member 136 are provided in positions that face each other via the thread pressing plates 180, 190.

By arranging the rod-shaped member 134 and the tubular member 136 in positions facing each other via the thread presser plates 180 and 190, it is possible to use the rod-shaped member 134 and the tubular member 136 to provide an upper thread path between the thread presser plates 180 and 190. In particular, as shown in FIG. 9, by providing an upper thread path that runs from the rod-shaped member 134 to the tubular member 136 and then returns to the rod-shaped member 134, two upper thread paths can be provided between the thread presser plates 180 and 190, and tension can be efficiently applied to the upper thread.

In addition, screw holes 138a and 138b are provided on the rear surface of the electromagnet holder 120 so that screws 226 and 228 can be screwed in to attach the electromagnet holder 120 to the mounting plate portion 110.

The electromagnet holder (second electromagnet holder) 140 is a holder in which a storage section (second storage section) 152 for storing the electromagnet 170 is open on the right side, and includes an upper surface section 142, an upper front surface section 144-1 that is connected downward from the end portion on the front side of the upper surface section 142, a rear surface section 146 that is connected downward from the end portion on the rear side of the upper surface section 122, a left side surface section 148 that is connected from the end portion on the left side side of the upper surface section 142, the end portion on the left side side of the upper front surface section 144-1, and the end portion on the left side side of the rear surface section 146, and a lower end portion of the rear surface section 146 and a left side surface section 148 that is connected from the lower end portion of the rear surface section 146 to the left side. It has a bottom surface portion 150 connected to the lower end portion of the surface portion 148, and a lower front surface portion 144-2 connected to the front end portion of the bottom surface portion 150 and the lower portion of the left side surface portion 148. The left side surface of the top surface portion 142, the left side surface of the left side surface portion 148, and the left side surface of the bottom surface portion 150 form a single plane, and the right side surface of the top surface portion 142, the right side surface of the top front surface portion 144-1, the right side surface of the back surface portion 146, the right side surface of the bottom surface portion 150, and the right side surface of the lower front surface portion 144-2 form a single plane.

The lower front part 144-2 has a lower front body 144-2a formed in a plate shape in the left-right direction, and a protrusion 144-2b that is connected to the right end of the lower front body 144-2a and protrudes to the front side, the lower front body 144-2a is connected to the left side surface part 148 and the bottom surface part 150, and the protrusion 144-2b is connected to the bottom surface part 150. A gap 149 is formed between the bottom end of the upper front part 144-1 and the top end of the lower front part 144-2, and a storage part 152 is provided on the rear side of the gap 149.

The storage section 152 is a storage section in which the end area on the opening 152K side is formed with a larger diameter than the other areas, and has a storage section main body 152-1 and a large diameter section 152-2 formed with a larger diameter than the storage section main body 152-1.

The storage unit main body 152-1 is a space surrounded by an inner peripheral surface 152a along the cylindrical periphery and a flat surface 152b on the left side surface side that is connected to the inner peripheral surface 152a, and the diameter of the inner peripheral surface 152a is formed to be larger than the outer diameter of the electromagnet 170 and smaller than the outer diameter of the thread pressing plate 190 so that the electromagnet 170 can be stored therein. When the thread tension applying unit 105 is assembled, the electromagnet 170 is stored in the storage unit main body 152-1.

The large diameter section 152-2 is a space surrounded by an inner circumferential surface 152c along the cylindrical circumferential surface and an annular flat surface 152d connected to the inner circumferential surface 152c, and the diameter of the inner circumferential surface 152c is formed to be larger than the outer diameter of the thread presser plate 190 so that the thread presser plate 190 can be housed therein. When the thread tension applying section 105 is assembled, the thread presser plate 190 is placed in the large diameter section 152-2. The flat surface 152d is also connected to the inner circumferential surface 152a.

The axial length (direction of axis Q) of storage section 152 (the sum of the axial length of inner circumferential surface 152a and the axial length of inner circumferential surface 152c) is longer than the axial length of storage section 132 by the amount that spring 200 is stored in, and is longer than the axial length of electromagnet 170.

The axial length of the large diameter portion 152-2 (the length of the inner peripheral surface 152c) is approximately the same as the thickness of the thread pressing plate 190 or is longer than the thickness of the thread pressing plate 190.

The lower surface of the upper front portion 144-1 and the upper surface of the lower front portion 144-2 are connected to the front end of the inner peripheral surfaces 152a and 152c. The center lines of the inner peripheral surfaces 152a and 152c are oriented in the direction of the axis Q.

The storage section 152 has an opening 152K on the side of the electromagnet holder 120. The electromagnet holder 120 and the electromagnet holder 140 are provided with a gap between them, and the opening 132K and the opening 152K face each other with a gap between them.

In addition, a recess 147 is provided in the left-right direction in the area from the rear end of the upper surface portion 142 to the upper end of the rear surface portion 146, and the recess 147 forms part of the inner circumferential surface of the cylindrical shape, so that the cylindrical rod-shaped member 134 fits into the recess 147.

In addition, a through hole 145 is formed in the left-right direction on the inner peripheral surface of the cylindrical shape of the protrusion 144-2b, and the cylindrical tubular member 136 can be inserted through it. A screw hole for screwing in a screw 154 is provided between the lower surface of the protrusion 144-2b and the through hole 145.

The electromagnet (first electromagnet) 160 has a magnetic body 162, a coil 164 wound around the magnetic body 162, and a cover portion 166 that houses the magnetic body 162 and the coil 164. The magnetic body 162 has an approximately cylindrical shape, and also has an approximately cylindrical shape when the magnetic body 162 and the coil 164 are in the state of being ... The center line of the cylindrical portion 166a faces the axis Q.

The axial length of the electromagnet 160 (in the direction of axis Q) is approximately the same as the axial length of the storage section 132 (the sum of the axial length of the inner circumferential surface 132a and the axial length of the inner circumferential surface 132c), but may be shorter than the axial length of the storage section 132.

The electromagnet (second electromagnet) 170 has the same configuration as the electromagnet 160, and includes a magnetic body 172, a coil 174 wound around the magnetic body 172, and a cover portion 176 that houses the magnetic body 172 and the coil 174. The magnetic body 172 is generally cylindrical, and also generally cylindrical when the magnetic body 172 and the coil 174 are in the state where they ... In order to allow the electromagnet 170 to move left and right within the storage section 152, the diameter of the cover section 176 is slightly smaller than the diameter of the inner circumferential surface 152a of the storage section 152 of the electromagnet holder 140. The center line of the cylindrical section 176a faces the direction of the axis Q.

The thread pressing plate (first thread pressing plate) 180 has a generally dish-like shape, a circular plate-like (specifically, flat) plate-like portion 182, and an edge portion 184 provided from the peripheral end of the plate-like portion 182, and the edge portion 184 has a tapered shape (i.e., a generally truncated cone shape) whose diameter increases with increasing distance from the peripheral end of the plate-like portion 182. The diameter of the plate-like portion 182 is formed to be larger than the outer diameter of the cover portion 166, so that the plate-like portion 182 can cover the left side surface of the electromagnet 160.

The thread pressing plate (second thread pressing plate) 190 has the same configuration as the thread pressing plate 180, and has a generally dish-shaped circular plate-like (specifically, flat) plate-like portion 192 and an edge portion 194 provided from the peripheral end of the plate-like portion 192, and the edge portion 194 has a tapered shape (i.e., a generally truncated cone shape) whose diameter increases as it moves away from the peripheral end of the plate-like portion 192. The diameter of the plate-like portion 192 is larger than the outer diameter of the cover portion 176, so that the plate-like portion 192 can cover the right side surface of the electromagnet 170.

The spring 200 is a coil spring, and is provided between the left side surface 148 and the electromagnet 170 with the axis (center line) of the spring 200 facing the direction of the axis Q. Specifically, one end of the spring 200 is fixed to the inner surface of the left side surface 148, i.e., the flat surface 152b of the storage section 152, and the other end is in contact with the circular plate section 176b of the cover section 176, and the spring 200 biases the electromagnet 170 toward the right side surface. In other words, the storage section 152 as the target storage section is provided with a spring (biasing means) 200 that biases the electromagnet 170 toward the opening 152K of the storage section 152.

In addition, the thread pressing plate 180, 190 is biased by a spring 200, and even when neither the electromagnet 160 nor the electromagnet 170 is excited, the plate portion 182 of the thread pressing plate 180 and the plate portion 192 of the thread pressing plate 190 are in contact with each other, the thread pressing plate 180 is in contact with the electromagnet 160, and the thread pressing plate 190 is in contact with the electromagnet 170. Therefore, when the electromagnets 160, 170 are excited, tension can be instantly applied to the upper thread, and the response to tension application can be made faster. In addition, the thread presser discs 180, 190 and the electromagnet 170 are biased by the spring 200, and the edge 184 of the thread presser disc 180 covers the peripheral end of the electromagnet 160, and the edge 194 of the thread presser disc 190 covers the peripheral end of the electromagnet 170, so that the thread presser discs 180, 190 do not fall off the thread tension applying section 105 even when the electromagnets 160, 170 are not excited. In addition, a part of the thread presser disc 180 is located within the large diameter section 132-2, and a part of the thread presser disc 190 is located within the large diameter section 152-2, so that the thread presser discs 180, 190 do not fall off the thread tension applying section 105 even when the electromagnets 160, 170 are not excited. The biasing force of the spring 200 may be the minimum biasing force that allows the thread presser discs 180 and 190 to come into contact with each other.

The upper thread guide 210 is a member for guiding the upper thread J sent from the wound thread to a position between the thread presser plate 180 and the thread presser plate 190, and has a vertical plate 212 and a horizontal plate 214 fixed to the lower end of the vertical plate 212.

The vertical plate portion 212 is in the form of a rectangular plate, with a horizontal length equal to the horizontal length of the mounting plate portion 110, and a vertical length shorter than the length from the upper end of the mounting plate portion 110 to the upper surface of the electromagnet holder 120.

The horizontal plate 214 is formed in a horizontal direction and perpendicular to the vertical plate 212. The horizontal plate 214 is provided with a guide hole 215 for inserting the upper thread J, and the guide hole 215 is provided at the corners of the front side and the left side side of the horizontal plate 214. However, in order to position the guide hole 215 near the positions of the thread pressing plates 180 and 190 in the left-right direction, the horizontal plate 214 protrudes to the left side further than the end of the left side of the vertical plate 212. The end of the right side of the horizontal plate 214 coincides with the end of the right side of the vertical plate 212. In other words, the horizontal plate 214 is formed longer in the horizontal direction than the vertical plate 212 by the amount that it protrudes to the left side further than the vertical plate 212. The horizontal plate 214 is provided with a hole for arranging the guide hole 215.

The guide hole 215 is cylindrical and has a cylindrical portion 215a provided inside the hole of the horizontal plate portion 214 and a ring-shaped portion 215b connected to the upper end of the cylindrical portion 215a. The outer diameter of the ring-shaped portion 215b is larger than the outer diameter of the cylindrical portion 215a, and the outer lower surface of the ring-shaped portion 215b is in contact with the upper surface of the horizontal plate portion 214. As shown in FIG. 9, the vertical cross section of the ring-shaped portion 215b has a pair of approximately semicircular shapes, and the upper side is formed in an arc shape, so that the upper thread J is not caught in the guide hole 215 and damaged.

When the upper thread guide portion 210 is attached to the mounting plate portion 110, a pair of screws 222 are screwed into the screw holes 110b.

All of the components constituting the thread tension applying unit 105 (specifically, the mounting plate 110, the electromagnet holder unit 119 (electromagnet holders 120, 140, rod-shaped member 134, cylindrical member 136, etc.), thread pressing plates 180, 190, spring 200, and upper thread guide unit 210) other than the electromagnets 160, 170 (except for the cover portions 166, 176) are made of non-magnetic materials. In other words, the above-mentioned components are made of non-magnetic materials so as not to interfere with the magnetic bodies 162, 172 attracting each other when the electromagnets 160, 170 are excited. Examples of non-magnetic materials include aluminum and stainless steel, and synthetic resins may be used as long as they have sufficient strength.

When the thread tension applying unit 105 is assembled, the electromagnet 160 is stored in the storage section 132 of the electromagnet holder 120, the electromagnet 170 is stored in the storage section 152 of the electromagnet holder 140, the spring 200 is provided between the left side surface section 148 and the cover section 176 of the electromagnet holder 140, and the thread pressing plates 180 and 190 are provided between the electromagnets 160 and 170. With this, the electromagnet holder 140 is The cylindrical member 136 is attached to the electromagnet holder 120, and by screwing the screw 137 into the electromagnet holder 120 and the screw 154 into the electromagnet holder 140, the cylindrical member 136 inserted into the through holes 125 and 145 is fixed to the electromagnet holder 120 and the electromagnet holder 140, and by fitting the rod-shaped member 134 into the through hole 127 and the recess 147, the electromagnet holder 140 is attached to the electromagnet holder 120. The upper thread guide portion 210 is also attached to the mounting plate portion 110.

The electromagnets 160 and 170 are provided with the magnetic bodies 162 and 172 facing each other (i.e., the magnetic bodies 162 and 172 face each other via the thread pressing plates 180 and 190), and in the thread pressing plates 180 and 190, the outer faces of the plate-shaped parts 182 and 192 (the faces opposite the edge side of each thread pressing plate) are arranged facing each other and are biased by the spring 200, so that the plate-shaped parts 182 and 192 are in contact with each other. In other words, the outer face 182a of the plate-shaped part 182 faces the left side, and the outer face 192a of the plate-shaped part 192 faces the right side, so that the outer faces 182a and 192a face each other.

When the thread tension applying unit 105 is attached to the housing unit 302, a pair of screws 220 are inserted into the insertion holes 110a and screwed into the screw holes 302b of the housing unit 302, and a pair of screws 224 are inserted into the insertion holes 110c and screwed into the screw holes 302c of the housing unit 302.

In addition, when the thread tension applying unit 105 is attached to the housing unit 302, a hole is provided on the right side of the electromagnet holder 120 in the housing unit 302 to lead out the wiring to the electromagnets 160 and 170. The wiring to the electromagnet 160 runs from the right side of the electromagnet holder 120 to the bottom side of the electromagnet holder 120 and reaches the electromagnet 160 through the cutout 129. The wiring to the electromagnet 170 runs from the right side of the electromagnet holder 120 to the cylindrical member 136, the wiring enters the cylindrical member 136 from the end of the right side of the cylindrical member 136, and is led out from the end of the left side of the cylindrical member 136. The wiring led out from the end of the left side of the cylindrical member 136 reaches the electromagnet 170 in the storage unit 152 through the gap 149 of the electromagnet holder 140.

In the thread tension applying section 105, the electromagnets 160 and 170 are excited so that the electromagnets 160 and 170 are attracted to each other, and the magnetic bodies 162 and 172 are attracted to each other, so that the electromagnets 160 and 170 approach each other. For example, by making the attracting surface of the magnetic body 162 an N pole and the attracting surface of the magnetic body 172 an S pole, the two attracting surfaces are attracted to each other, so that the electromagnets 160 and 170 approach each other. Then, the thread presser plate 180 is pressed by the electromagnet 160, and the thread presser plate 190 is pressed by the electromagnet 170, so that the plate-shaped portion 182 of the thread presser plate 180 and the plate-shaped portion 192 of the thread presser plate 190 are pressed against each other, so that the upper thread J between the plate-shaped portions 182 and 192 is sandwiched between the plate-shaped portions 182 and 192. With the upper thread J sandwiched between them, tension is applied to the upper thread J by pulling the upper thread J with the thread take-up lever 306.

When the thread take-up spring mechanism 5 and the thread tension applying unit 105 are attached to the housing 302 of the arm 301, the positional relationship between the thread take-up spring mechanism 5 and the thread tension applying unit 105 is such that the upper thread J that passes between the thread pressure plate 180 and the thread pressure plate 190 comes into contact with the circumferential surface of the shaft 46 and then engages with the thread locking unit 56, so that the thread take-up spring mechanism 5 is located below the thread tension applying unit 105 as shown in Figures 1, 8, and 10, and preferably is located such that the boundary line (vertical boundary line) between the thread pressure plate 180 and the thread pressure plate 190 coincides with the vertical tangent at the right side of the circumferential surface of the shaft 46.

In other words, the extension of the boundary line (vertical boundary line) between the thread pressing plate 180 and the thread pressing plate 190 is in contact with the end of the right side of the shaft 46, and the upper thread J guided vertically between the thread pressing plate 180 and the thread pressing plate 190 comes in contact with the circumferential surface of the shaft 46 without changing its vertical direction, and after coming in contact with the circumferential surface of the shaft 46, it curves along the circumferential surface of the shaft 46 to the left side, and then leaves the circumferential surface of the shaft 46 and is engaged with the thread engaging portion 56.

In this way, by locating the boundary line (vertical boundary line) between the thread presser discs 180 and 190 and the vertical tangent to the circumferential surface of the shaft 46 (the position where the boundary line and the tangent line coincide), the upper thread J led out from the thread tension applying section 105 is smoothly led to the thread take-up spring mechanism 5, and no unnecessary load is placed on the upper thread J. For example, if the thread take-up spring mechanism 5 is shifted to the left or right from the position where the boundary line and the tangent line coincide, the upper thread J may come into contact with the lower end of the thread presser discs 180, 190 and bend at the lower end, placing a load on the upper thread J, or the upper thread J may come into contact with the lower end of the electromagnet holders 120, 140 and placing a load on the upper thread J. However, if the boundary line and the tangent line coincide, there is no such risk.

As shown in Figs. 1 and 10, the thread take-up spring mechanism 5 is provided near the guide member 304 attached to the housing 302. The guide member 304 is provided in a position between the thread locking portion 56 and the balance 306 in the upper thread path, and is provided in a position where the upper thread J can pull the thread locking unit 57 and rotate it downward (specifically, the magnet portion 64 can rotate in a direction away from the magnetic sensor 80) when the balance 306 pulls the upper thread J (in the example of Fig. 1, when it pulls it upward). Specifically, when the upper thread J is not pulling the thread locking portion 56, the guide member 304 is provided in a position diagonally below the intermediate portion 60 of the thread locking portion 56 (diagonally below the intermediate portion 60 on the opposite side to the shaft portion 46 side in front view (i.e., diagonally below the left in the example of Fig. 10)).

When the thread tension applying unit 105 is attached to the housing 302, the rear surface of the mounting plate 110 is in contact with the front surface of the housing 302, and the left side surface of the electromagnet holder 120 and the right side surface of the electromagnet holder 140 are attached at right angles to the front surface of the housing 302 and parallel to an imaginary plane facing up and down. As a result, the outer surface 182a of the plate-shaped portion 182 of the thread pressing plate 180 faces the left side, and the outer surface 192a of the plate-shaped portion 192 of the thread pressing plate 190 faces the right side.

When the thread take-up spring mechanism 5 is attached to the front surface of the housing 302, the magnetic sensor attachment section 78 is located above the cylindrical section 74, and the magnetic sensor 80 faces the left side. When the thread locking unit 57 is not rotated, the magnet section 64 is located diagonally below the left side of the magnetic sensor 80, and the thread locking section 56 is located on the left side of the thread take-up spring attachment section 42.

To attach the thread tension control device 1 to the housing 302, the thread take-up spring mechanism 5 and the thread tension applying unit 105 are attached to the housing 302. To attach the thread take-up spring mechanism 5, the insertion locking unit 10 is inserted into the mounting hole 302a and then the insertion locking unit 10 is rotated to lock the locking unit 16 into the mounting hole 302a.

To attach the thread tension applying unit 105 to the housing 302, a pair of screws 220 are inserted into the insertion holes 110a and screwed into the screw holes 302b of the housing 302, and a pair of screws 224 are inserted into the insertion holes 110c and screwed into the screw holes 302c of the housing 302. In other words, the thread tension applying unit 105 is attached to the housing 302 by attaching the mounting plate 110 to the housing 302.

The path of the upper thread J in the thread tension control device 1 will be explained using Figures 1, 8 to 10. The upper thread J sent from the wound thread passes through the guide hole 215 of the upper thread guide section 210, reaches the thread tension applying section 105, contacts the peripheral surface of the rod-shaped member 134, passes between the thread pressing plate 180 and the thread pressing plate 190, contacts the peripheral surface of the tubular member 136 and turns around, passes between the thread pressing plate 180 and the thread pressing plate 190, contacts the peripheral surface of the rod-shaped member 134, then goes downward, leaves the thread tension applying section 105, and reaches the thread take-up spring mechanism section 5. In other words, the upper thread J passes from the rod-shaped member 134 to the tubular member 136 and then returns to the rod-shaped member 134, so that the upper thread J is suspended between the rod-shaped member 134 and the tubular member 136, passing between the thread pressing plate 180 and the thread pressing plate 190 twice.

The upper thread J is then fed to the thread take-up spring mechanism 5, comes into contact with the circumferential surface of the shaft 46, and is then locked by the thread locking portion 56. After being locked by the thread locking portion 56, the thread is locked by the guide member 304, and then reaches the thread take-up lever 306. After passing through the thread take-up lever 306, the upper thread J reaches the sewing needle of the needle bar 308.

In other words, the thread take-up spring mechanism 5 is provided upstream of the thread take-up lever 306 on the upper thread path, and the thread tension applying unit 105 is provided upstream of the thread take-up spring mechanism 5 on the upper thread path, and the upper thread path is provided between the thread presser plate 180 and the thread presser plate 190.

The schematic configuration of a sewing machine equipped with the thread tension control device 1 is shown in FIG. 11, where the thread take-up lever 306, needle bar 308, and shuttle 310 are driven by transmitting the rotational force of the main shaft 312 via a power transmission means such as a cam mechanism or belt mechanism, and the main shaft 312 is driven by a main shaft motor 314.

The control circuit (control unit) 316 is a circuit that controls the operation of the main shaft motor 314 and the electromagnets 160, 170, and controls the operation of each unit according to the data stored in the memory device 318. In other words, the control circuit 316 creates main shaft data (see FIG. 14) according to the embroidery data read from the memory device 318, and controls the operation of the main shaft motor 314 according to the created main shaft data. It also controls the operation of the electromagnets 160, 170 according to the detection results of the magnetic sensor 80.

Then, the positions of the thread take-up lever 306, needle bar 308, and shuttle (position between top dead center and bottom dead center) are determined as shown in FIG. 15 according to the spindle angle (i.e., the position in the rotational direction of the spindle), or more precisely, the angle of the spindle motor 314 that drives the spindle (i.e., the position in the rotational direction of the spindle motor). The spindle angle is detected by an encoder provided between the spindle motor 314 and the control circuit 316.

As shown in FIG. 12, the embroidery data stores data on the stitch width (i.e., the stitch width value), stitch direction (i.e., the value indicating the stitch direction), and thread type for each stitch. This embroidery data is stored in the storage device 318 by inputting it from the outside via the input/output device 320. Here, the stitch direction is data on the angle value relative to a predetermined direction (for example, one of the horizontal directions).

In addition, the memory device 318 stores current data (Figure 13) that stores data on the current value when the electromagnets 160 and 170 are excited for each stitch.

The current value in this current data is created according to the stitch width, stitch direction, and thread type of each stitch. For example, if the stitch width is long, the upper thread needs to be tightened, so the current value is increased (if the stitch width is short, the current value is decreased). Also, if the stitch direction is significantly different from the direction of the previous stitch, the upper thread is already tightly tightened, so the current value is decreased (if the stitch direction is slightly different from the direction of the previous stitch, the current value is increased). Also, if the thread is thick, the upper thread needs to be tightened, so the current value is increased (if the thread is thin, the current value is decreased). Also, if the upper thread is to be tightened, the current value is increased (if the upper thread is to be loosely tightened, the current value is decreased). If the embroidery finish is to be made firm, the current value is increased.

The operation of the thread tension control device 1 configured as above will now be described. In the sewing machine, the thread take-up lever 306, the needle bar 308, and the shuttle 310 are driven by transmitting the rotational force of the main shaft 312 via a power transmission means such as a cam mechanism or a belt mechanism.

In addition, in the section where the thread take-up 306 pulls the upper thread J against the work cloth, that is, the section where the thread take-up 306 rises and the needle bar 308 descends, the upper thread J is tightened against the work cloth. Therefore, in the section where the thread take-up 306 rises and the needle bar 308 descends, tension can be applied to the upper thread J by clamping the upper thread J between the two thread pressure plates 180, 190 using the thread tension applying unit 105.

Then, when the balance 306 rises and pulls the upper thread J, the upper thread J engaged with the thread engaging portion 56 rotates the thread engaging unit 57, the distance between the magnet portion 64 and the magnetic sensor 80 increases, and when the value of the magnetic force detected by the magnetic sensor 80 becomes smaller than a predetermined value (this case is considered to be when the magnetic force is detected as off by the magnetic sensor 80), the two electromagnets 160 and 170 are excited, causing the electromagnets 160 and 170 to attract each other.

When the magnetic sensor 80 detects that the magnetic force is off, the position of the magnet unit 64 is such that the upper thread J is tightened when the thread take-up 306 rises and the needle bar 308 falls. In FIG. 15, the magnetic force at the position of the magnet unit 64 when the thread take-up 306 is located at any position in the section (i.e., about 0 degrees to about 60 degrees) where the section where the thread take-up 306 rises (about 300 degrees to about 60 degrees) and the section where the needle bar falls (about 0 degrees to about 180 degrees in FIG. 15) overlap is set as a threshold value (predetermined magnetic force value), and when the magnetic force detected by the magnetic sensor 80 becomes less than the threshold value, the magnetic force is detected as off. For example, if the position in that section is set to a 10 degree position, the detection value of the magnetic sensor 80 at the position of the magnet unit 64 when the thread take-up 306 is located at a 10 degree position is set as the threshold value.

When the magnetic sensor 80 detects that the magnetic force is off, the electromagnets 160 and 170 are excited, causing the electromagnets 160 and 170 to be attracted to each other, and the upper thread J is sandwiched between the thread presser discs 180 and 190. The thread take-up 306 pulls the upper thread J while the upper thread J is sandwiched, so tension is applied to the upper thread J. Note that if the magnetic force of the electromagnets 160 and 170 is increased, the force with which the thread presser discs 180 and 190 sandwich the upper thread J becomes stronger, and therefore the tension applied to the upper thread J becomes greater.

In addition, when the balance 306 is released from pulling the upper thread, the thread locking unit 57 rotates back to its original position, the distance between the magnet section 64 and the magnetic sensor 80 is shortened, and the value of the magnetic force detected by the magnetic sensor 80 exceeds a predetermined value (this is considered to be when the magnetic sensor 80 detects that the magnetic force is on), the excitation of the two electromagnets 160, 170 is stopped, the attraction between the electromagnets 160 and 170 is released, and tension applied to the upper thread is released.

The specific operation of the thread tension control device 1 is as shown in the flowchart of FIG. 16. First, the target stitch is set to 1 (i.e., stitch 1) (S1). During the period of stitch 1, it is detected whether the magnetic force is detected as off by the magnetic sensor 80 (S2). If the magnetic force is detected as off, the current value for the corresponding stitch is read from the current data (S3). According to the read current value, the two electromagnets 160 and 170 are excited to attract the electromagnets 160 and 170 (S4). In other words, the electromagnets 160 and 170 are excited so that the electromagnets 160 and 170 are attracted to each other, and the electromagnets 160 and 170 are excited simultaneously. In other words, when the thread locking unit 57 rotates and the magnetic force detected by the magnetic sensor 80 is turned off, the electromagnets 160 and 170 are excited to apply tension to the upper thread.

Then, when the rotation of the thread locking unit 57 returns to its original position and the magnetic force detected by the magnetic sensor 80 turns ON, the excitation of the electromagnets 160 and 170 is stopped (S5, S6). In other words, when the magnetic force turns ON, the balance 306 is no longer pulling the upper thread upward, and there is no need to apply tension to the upper thread, so the excitation of the electromagnets 160 and 170 is stopped. To stop the excitation of the electromagnets 160 and 170, the supply of current to the electromagnets 160 and 170 is stopped, and the supply of current to the electromagnets 160 and 170 is stopped simultaneously. Note that the excitation of the electromagnets 160 and 170 continues until the magnetic force turns ON.

Then, it is determined whether the target stitch is the final stitch or not (S7). If it is the final stitch, the process ends. If it is not the final stitch, the target stitch is updated (S8). In other words, if the target stitch is 1, the target stitch is changed to 2.

After that, the process returns to step S2. When the magnetic sensor 80 detects that the current is off, the current value for stitch 2 is read from the current data (S3), and the electromagnets 160 and 170 are excited according to the current value (S4). The excitation continues until the electromagnets are detected as on (S5, S6). The above operations are repeated to apply tension to the upper thread for each stitch.

As described above, according to the yarn tension control device 1 of this embodiment, when applying yarn tension, it is sufficient to excite the electromagnets 160 and 170 so that the electromagnets 160 and 170 are attracted to each other. In particular, by simultaneously exciting the electromagnets 160 and 170, the electromagnets 160 and 170 can be attracted to each other quickly, thereby enabling a high-speed response in applying tension.

In addition, when thread tension application is to be cut off, the supply of current to electromagnet 160 and the supply of current to electromagnet 170 can be stopped, without reverse exciting the electromagnets. In addition, by simultaneously stopping the supply of current to electromagnet 160 and the supply of current to electromagnet 170, the excitation of electromagnets 160 and 170 can be quickly cut off, allowing for a high-speed response to tension cutoff. Since the response to tension application and tension cutoff can be made quickly, tension control can be performed for each stitch.

In addition, when no tension is applied to the thread, the current supply to the electromagnets 160, 170 can be stopped, and the electromagnets do not need to be continuously reverse excited, so heat generation in the electromagnets 160, 170 can be suppressed and the electromagnets 160, 170 can be made smaller.

In addition, since thread tension is applied by two electromagnets 160, 170, a large thread tension can be applied, and as a result, a wide range of thread tension can be applied, from no thread tension to a large thread tension.

In addition, the electromagnets 160 and 170 are controlled according to the detection results of the magnetic sensor 80 based on the behavior of the thread locking unit 57 in the thread take-up spring mechanism 5, so they are not related to other control signals in the control circuit 316 in the sewing machine (for example, the control signal that controls the main shaft motor 314), making it easy to install on existing sewing machines.

In addition, since the thread take-up spring mechanism 5 and the thread tension applying unit 105 are formed separately, when installing the thread tension control device 1 on an existing sewing machine, the installation positions of the thread take-up spring mechanism 5 and the thread tension applying unit 105 can be adjusted, making installation on an existing sewing machine easy.

In addition, by providing current data, the current value when exciting the electromagnets 160, 170 for each stitch can be adjusted, thereby controlling the upper thread tension for each stitch.

In addition, since two electromagnets 160, 170 are provided, when it is desired to release the tension on the upper thread, such as when cutting the upper thread (i.e., when performing thread cutting), the electromagnets 160 and 170 can be made to have mutually repelling polarities (i.e., reverse excitation) so that no tension is applied by the spring 200, and the tension on the upper thread can be reliably cut off.

The thread tension control device 1 can be used not only to control the tension of the upper thread but also for other purposes.

For example, in the section where the thread take-up 306 rises, the thread take-up 306 pulls the upper thread J, so the magnetic sensor 80 should detect the magnetic force as off by the time the thread take-up 306 reaches the top dead point. However, if the upper thread J is broken, the thread take-up 306 cannot pull the upper thread J, so the magnetic sensor 80 continues to detect the magnetic force as on. Therefore, in the section where the thread take-up 306 rises in a certain stitch (in the example of FIG. 15, (approximately 300 degrees to approximately 80 degrees)), if the detection result of the magnetic sensor 80 remains on (i.e., does not turn off) (in actuality, if the detection result of the magnetic sensor 80 remains on in a certain stitch), it can be determined that the thread locking unit 57 does not rotate and the upper thread J is likely to be broken. In other words, the thread tension control device 1 can be used to detect thread breakage in the upper thread. In reality, there may be stitches in which the thread take-up lever 306 does not rise, so if the detection result of the magnetic sensor 80 remains on (i.e., does not turn off) for a period of time equivalent to multiple stitches, it can be determined that there is a high possibility that the upper thread has broken.

In addition, when the upper thread passes through the hook 310 (the upper thread is held by the hook 310 rotating downwards), the upper thread is pulled by the hook 310, causing the thread holding unit 57 to rotate (in the example of Figure 15, the upper thread J is pulled by the hook 310 in the range of approximately 245 degrees to approximately 290 degrees), and when the take-up lever 306 then rises, the upper thread J is further pulled by the take-up lever 306, causing the thread holding unit 57 to rotate further (in the example of Figure 15, the upper thread J is pulled by the take-up lever 306 in the range of approximately 300 degrees to approximately 80 degrees). However, if the upper thread J does not pass through the hook 310, i.e., if a skipped stitch occurs, the upper thread J is not pulled by the hook 310, and so the thread holding unit 57 does not rotate in that section. In FIG. 15, the range from approximately 245 degrees to approximately 290 degrees is the section in which the balance 306 descends.

Therefore, if the detection result of the magnetic sensor 80 remains on (i.e., does not turn off) in the section where the balance 306 descends and the upper thread J passes through the shuttle 310 (in the example of FIG. 15, the range from approximately 245 degrees to approximately 290 degrees), it can be determined that there is a high possibility that a skip has occurred. In other words, the thread tension control device 1 can be used to detect skipped stitches.

In the above description, the spring 200 is provided in the storage section 152 of the electromagnet holder 140, but it may also be provided in the storage section 132 of the electromagnet holder 120 (i.e., the storage section 132 is the target storage section). In that case, the axial length of the storage section 132 is formed to be longer than the axial length of the storage section 152.

In the above description, the spring 200 is provided, but the spring 200 may be omitted. That is, even when the electromagnet 160 contacts the flat surface 132b on the right side of the storage section 132 and the electromagnet 170 contacts the flat surface 152b on the left side of the storage section 152 (i.e., when the distance between the electromagnets 160 and 170 is the greatest), if a part of the thread pressing plate 180 is located within the large diameter section 132-2 and a part of the thread pressing plate 190 is located within the large diameter section 152-2, and there is no risk of the thread pressing plate 180, 190 falling, the spring 200 may be omitted.

In the above explanation, current data is provided to determine the current value when magnetizing the electromagnets 160, 170 for each stitch, and the magnitude of the upper thread tension is controlled for each stitch. However, without providing such current data, the current value when magnetizing the electromagnets 160, 170 may be the same for each stitch, and while the magnetic force detected by the magnetic sensor 80 is off, the electromagnets 160, 170 may be excited to apply the upper thread tension.

Even if the current value when energizing the electromagnets 160, 170 is the same for each stitch in this way, it is possible to obtain the above-mentioned effects other than the effect of being able to control the upper thread tension for each stitch. In other words, it is possible to quickly respond to tension application and tension interruption, it is possible to interrupt thread tension application even when the electromagnets are not excited, it is possible to miniaturize the electromagnets 160, 170, it is possible to apply a wide range of thread tension from no thread tension to a high thread tension, and it is easy to install on existing sewing machines. In particular, since there is no need to provide current data, it can be said that it is easier to install on existing sewing machines.

In the above description, the thread tension control device 1 is provided in the area to the right of the balance 306 in the housing 302 when viewed from the front, but the thread tension control device 1 may be configured symmetrically and provided in the area to the left of the balance 306 when viewed from the front.

Next, we will explain modified examples of the thread tension control device 1. The thread tension control device 1A as the first modified example is configured as shown in FIG. 17 and has a configuration substantially similar to that of the thread tension control device 1, but the configuration of the thread take-up spring mechanism is different.

That is, the thread tension control device 1A has a thread take-up spring mechanism 5' and a thread tension applying unit 105. The thread take-up spring mechanism 5' has a configuration that is substantially the same as the thread take-up spring mechanism 5, but the position of the magnetic sensor mounting part 78 is different when the thread take-up spring mechanism 5' is attached to the housing part 302, the mounting position of the magnetic sensor 80 relative to the magnetic sensor mounting part 78 is different, and further, the mounting state of the thread take-up spring unit 50 relative to the thread take-up spring mounting part 42 is different.

In other words, when the thread take-up spring mechanism 5 is attached to the housing 302, the magnetic sensor attachment part 78 is provided on the right side of the cylindrical part 74, and the magnetic sensor 80 is provided on the bottom side of the magnetic sensor attachment part 78. In other words, compared to the case of the thread take-up spring mechanism 5, the tip unit 70 rotates approximately 90 degrees to the right when viewed from the front, and the magnetic sensor 80 is located on the bottom side of the magnetic sensor attachment part 78.

Furthermore, the thread take-up spring unit 50 is symmetrical with respect to the thread take-up spring unit 50 of the thread take-up spring mechanism 5, with respect to a virtual plane passing through the axis P and tilted approximately 45 degrees to the right side from the vertical direction. In other words, the thread take-up spring unit 50 of the thread take-up spring mechanism 5' has a thread take-up spring 51 formed of a linear member and a magnet part 64 attached to the thread take-up spring 51, and the thread take-up spring 51 has a winding part (not shown) fixed to the thread take-up spring mounting part 42, a protruding part 54 connected to the end of the winding part, and a thread locking part 56 connected to the tip of the protruding part 54. In addition, the winding portion 52 of the thread take-up spring mechanism 5 is wound from the base end of the protrusion 54 to the right along the periphery of the thread take-up spring mounting portion 42 toward the front side, while the winding portion of the thread take-up spring mechanism 5' is wound from the base end of the protrusion 54 to the left along the periphery of the thread take-up spring mounting portion 42 toward the front side.

The magnet portion 64 attached to the protrusion 54 is located below the magnetic sensor 80 (strictly speaking, diagonally below and to the left of the magnetic sensor 80 when viewed from the front), and the middle portion 60 of the thread locking portion 56 is located below the shaft portion 46.

The positional relationship between the thread take-up spring mechanism 5' and the thread tension applying unit 105 when they are attached to the housing 302 is the same as in the case of the thread tension control device 1, and the thread take-up spring mechanism 5' is positioned below the thread tension applying unit 105, preferably so that the boundary line (vertical boundary line) between the thread pressing plate 180 and the thread pressing plate 190 coincides with the vertical tangent at the right side of the periphery of the shaft 46.

As in the case of the thread tension control device 1, the thread take-up spring mechanism 5' is provided near the guide member 304 as shown in FIG. 17. The guide member 304 is provided at a position between the thread locking portion 56 and the balance 306 in the upper thread path, and is provided at a position where, when the balance 306 pulls the upper thread J, the upper thread J can pull the thread locking unit 57 and rotate it to the left as viewed from the front (specifically, the magnet portion 64 can rotate in a direction away from the magnetic sensor 80). Specifically, when the upper thread J is not pulling the thread locking portion 56, the guide member 304 is provided at a position to the left of the middle portion 60 of the thread locking portion 56 as viewed from the front.

The method of mounting the thread tension control device 1A to the housing 302 is the same as that of the thread tension control device 1, and the thread take-up spring mechanism 5' and the thread tension applying unit 105 are mounted to the housing 302. The method of mounting the thread take-up spring mechanism 5' is the same as that of the thread take-up spring mechanism 5 of the thread tension control device 1, and the method of mounting the thread tension applying unit 105 is the same as that of the thread tension applying unit 105 of the thread tension control device 1.

The path of the upper thread J in the thread tension control device 1A is the same as that in the thread tension control device 1, and the upper thread that passes through the thread tension applying section 105 is sent to the thread take-up spring mechanism section 5', where the upper thread J comes into contact with the circumferential surface of the shaft section 46, then engages with the thread locking section 56, and then engages with the guide member 304, and then reaches the thread take-up lever 306. The upper thread J that passes through the thread take-up lever 306 reaches the sewing needle of the needle bar 308, but while in the thread take-up spring mechanism section 5, the upper thread J comes into contact with the upper side of the middle section 60 of the thread locking section 56, in the thread take-up spring mechanism section 5', the thread locking section 56 is provided to the right of the guide member 304, so the upper thread J comes into contact with the lower side of the middle section 60 of the thread locking section 56.

The operation of the thread tension control device 1A is the same as that of the thread tension control device 1. When the balance 306 rises and pulls the upper thread J, the upper thread J engaged with the thread engagement portion 56 rotates the thread engagement unit 57 (rotates it to the right when viewed from the front), and when the magnetic sensor 80 detects that the magnet portion 64 has left the magnetic sensor 80 (i.e., in this case, the magnetic sensor 80 detects that the magnetic force is off), the two electromagnets 160, 170 are excited, causing the electromagnets 160 and 170 to attract each other, thereby applying tension to the upper thread.

The specific operation is similar to that described above in the flowchart of Figure 16, so a detailed explanation will be omitted.

The thread tension control device 1A also provides high-speed response when applying or cutting tension, allowing tension control for each stitch, thread tension can be cut off even when the electromagnets are not excited, electromagnets 160 and 170 can be made smaller, a wide range of thread tension can be applied, from no thread tension to high thread tension, and installation on existing sewing machines is easy. In addition, by providing current data, the current value when exciting electromagnets 160 and 170 for each stitch can be adjusted, allowing the upper thread tension to be controlled for each stitch.

Next, another modified example of the thread tension control device 1 will be described. The thread tension control device 1B as a second modified example is configured as shown in Figures 18 to 20, and has a configuration that is substantially the same as the thread tension control device 1, but differs in that the thread take-up spring mechanism 5 and the thread tension applying unit 105 are integrated into one unit. In other words, while the thread tension control device 1 has the thread take-up spring mechanism 5 and the thread tension applying unit 105 as separate bodies, the thread tension control device 1B has the thread take-up spring mechanism 5 and the thread tension applying unit 105 integrated into one unit.

In other words, in the thread tension control device 1B, as shown in Figures 18 and 19, the mounting plate portion 20 and the mounting plate portion 110 are formed by one mounting plate unit 100, and the mounting plate portion 20, the mounting plate portion 110, and the intermediate plate portion 111 between the mounting plate portion 20 and the mounting plate portion 110 form the mounting plate unit 100, which is composed of a single plate-shaped member. As a result, the fixed unit 9 has a plate-shaped portion (the mounting plate unit 100 and the intermediate plate portion 111) that extends toward the thread tension applying portion 105, and the electromagnet holder unit 119 is provided on the plate-shaped portion.

That is, the thread tension control device 1B has a thread take-up spring mechanism 5, a thread tension applying unit 105, and an intermediate plate 111, the thread take-up spring mechanism 5 has an insertion locking unit 10, an attachment plate 20, a guide wall 30, a central configuration unit 40, a thread take-up spring unit 50, a tip unit 70, and a magnetic sensor 80, and the thread tension applying unit 105 has an attachment plate 110, an electromagnet holder 120, an electromagnet holder 140, an electromagnet 160, an electromagnet 170, thread pressing plates 180, 190, a spring 200, and an upper thread guide 210.

Here, the thread take-up spring mechanism 5 has the same configuration as the thread take-up spring mechanism 5 of the thread tension control device 1, except that the mounting plate 20 is integrated with the mounting plate 110 and the intermediate plate 111 as the mounting plate unit 100, so a detailed explanation will be omitted.

The thread tension applying unit 105 has the same configuration as the thread tension applying unit 105 of the thread tension control device 1, except that the mounting plate unit 110 is integrated with the mounting plate unit 20 and the intermediate plate unit 111 as the mounting plate unit 100, so a detailed description will be omitted.

Here, the mounting plate unit 100 will be described. The mounting plate unit 100 is generally plate-shaped and has a mounting plate portion 20 which is a circular plate-shaped region, a mounting plate portion 110 which is a vertically elongated rectangular plate-shaped region, and an intermediate plate portion 111 which is a region connecting the lower end of the mounting plate portion 110 and the upper right part of the mounting plate portion 20. The intermediate plate portion 111 is connected to the lower end of the mounting plate portion 110 and the intermediate plate portion 111 is connected to the upper right part of the mounting plate portion 20. In other words, the intermediate plate portion 111 has a left side 111a which extends downward from the left side of the mounting plate portion 110 and is formed to the outer periphery (arc-shaped side portion) of the mounting plate portion 20, and a right side 111b which is formed in a straight line diagonally downward from the lower end of the right side of the mounting plate portion 110. The right side 111b is inclined downwards and to the left, and when viewed from the front, the right side 111b is in contact with the outer periphery of the mounting plate portion 20 so that it is tangent to the outer periphery of the mounting plate portion 20.

The method of mounting the thread tension control device 1B to the housing part 302 is the same as that of the thread tension control device 1, and the insertion locking part 10 is inserted into the mounting hole of the housing part 302 and locked, and the pair of screws 220 and the pair of screws 224 are screwed into the housing part 302. Note that the mounting using the pair of screws 220 and the pair of screws 224 may be omitted, and the insertion locking part 10 may be mounted to the housing part 302 only by inserting and locking it.

The path of the upper thread J in the thread tension control device 1B is the same as in the thread tension control device 1.

The operation of the thread tension control device 1B is the same as that of the thread tension control device 1. When the balance 306 rises and pulls the upper thread J, the upper thread J engaged with the thread engagement portion 56 rotates the thread engagement unit 57 (rotates it to the left when viewed from the front), and when the magnetic sensor 80 detects that the magnet portion 64 has left the magnetic sensor 80 (i.e., in this case, the magnetic sensor 80 detects that the magnetic force is off), the two electromagnets 160, 170 are excited, causing the electromagnets 160 and 170 to attract each other, thereby applying tension to the upper thread.

The specific operation is similar to that described above in the flowchart of Figure 16, so a detailed explanation will be omitted.

The thread tension control device 1B can also quickly respond to tension application and tension interruption, allowing tension control for each stitch, thread tension application can be interrupted even when the electromagnets are not excited, electromagnets 160, 170 can be made smaller, a wide range of thread tension can be applied from no thread tension to high thread tension, and installation on existing sewing machines is easy. In addition, by providing current data, the current value when exciting electromagnets 160, 170 for each stitch can be adjusted, allowing the upper thread tension to be controlled for each stitch.

Furthermore, in the thread tension control device 1B, the thread take-up spring mechanism 5 and the thread tension applying unit 105 are configured as one unit, so there is no need to adjust the positional relationship between the thread take-up spring mechanism 5 and the thread tension applying unit 105 when attaching it to the housing unit 302.

Next, another modified example of the thread tension control device 1 will be described. The thread tension control device 1C as a third modified example is configured as shown in FIG. 21 and is substantially the same as the thread tension control device 1A, but differs in that the thread take-up spring mechanism 5' and the thread tension applying unit 105 are integrated into one unit. In other words, while the thread tension control device 1A has the thread take-up spring mechanism 5' and the thread tension applying unit 105 as separate bodies, the thread tension control device 1C has the thread take-up spring mechanism 5' and the thread tension applying unit 105 as one body.

In other words, in the thread tension control device 1C, as shown in FIG. 21, the mounting plate portion 20 and the mounting plate portion 110 are formed by one mounting plate unit 100, and the mounting plate portion 20, the mounting plate portion 110, and the intermediate plate portion 111 between the mounting plate portion 20 and the mounting plate portion 110 form the mounting plate unit 100, which is composed of a single plate-shaped member.

Here, the thread take-up spring mechanism 5' has the same configuration as the thread take-up spring mechanism 5' of the thread tension control device 1A, except that the mounting plate 20 is integrated with the mounting plate 110 and the intermediate plate 111 as the mounting plate unit 100, so a detailed explanation will be omitted.

The thread tension applying unit 105 has the same configuration as the thread tension applying unit 105 of the thread tension control device 1A, except that the mounting plate unit 110 is integrated with the mounting plate unit 20 and the intermediate plate unit 111 as the mounting plate unit 100, so a detailed description will be omitted.

In addition, the mounting plate unit 100 in the thread tension control device 1C has the same configuration as the mounting plate unit 100 in the thread tension control device 1B, so a detailed description will be omitted.

The method of mounting the thread tension control device 1C to the housing part 302 is the same as that of the thread tension control device 1A, and the insertion locking part 10 is inserted into the mounting hole of the housing part 302 and locked, and the pair of screws 220 and the pair of screws 224 are screwed into the housing part 302. Note that the mounting using the pair of screws 220 and the pair of screws 224 may be omitted, and the insertion locking part 10 may be mounted to the housing part 302 simply by inserting and locking it.

The path of the upper thread J in the thread tension control device 1C is the same as in the thread tension control device 1A.

The operation of the thread tension control device 1C is the same as that of the thread tension control device 1. When the balance 306 rises and pulls the upper thread J, the upper thread J engaged with the thread engagement portion 56 rotates the thread engagement unit 57 (rotates it to the right when viewed from the front), and when the magnetic sensor 80 detects that the magnet portion 64 has left the magnetic sensor 80 (i.e., in this case, the magnetic sensor 80 detects that the magnetic force is off), the two electromagnets 160, 170 are excited, causing the electromagnets 160 and 170 to attract each other, thereby applying tension to the upper thread.

The specific operation is similar to that described above in the flowchart of Figure 16, so a detailed explanation will be omitted.

The thread tension control device 1C can also quickly respond to tension application and tension interruption, allowing tension control for each stitch, thread tension application can be interrupted even when the electromagnets are not excited, electromagnets 160, 170 can be made smaller, a wide range of thread tension can be applied from no thread tension to high thread tension, and installation on existing sewing machines is easy. In addition, by providing current data, the current value when exciting electromagnets 160, 170 for each stitch can be adjusted, and the upper thread tension can be controlled for each stitch.

Furthermore, in the thread tension control device 1C, the thread take-up spring mechanism 5' and the thread tension applying unit 105 are configured as one unit, so there is no need to adjust the positional relationship between the thread take-up spring mechanism 5 and the thread tension applying unit 105 when attaching it to the housing unit 302.

In each of the modified examples of the yarn tension control devices 1A to 1C, the spring 200 may be provided in the storage section 132 of the electromagnet holder 120, or the spring 200 may be omitted.

The current value used to excite the electromagnets 160, 170 may be the same for each stitch, and the thread tension control devices 1A-1C may be configured symmetrically and provided in the area to the left of the thread take-up lever 306 when viewed from the front.

REFERENCE SIGNS LIST 1, 1A, 1B, 1C Thread tension control device 5 Thread take-up spring mechanism 5' Thread take-up spring mechanism 9 Fixed unit 10 Insertion locking portion 11 Screw hole 12 Cylindrical portion 14 Annular portion 16 Locking portion 20 Mounting plate portion 21 Through hole 30 Guide wall portion 31 Through hole 32 Center portion 34 Annular convex portion 35 Inner inclined portion 36 Convex portion 37 Outer inclined portion 40 Central component unit 41 Central component portion 42 Thread take-up spring mounting portion 44 Shaft portion 46 Shaft portion 48 Shaft portion 50 Thread take-up spring unit 51 Thread take-up spring 52 Winding portion 54 Protruding portion 56 Thread locking portion 57 Thread locking unit 58 Base end portion 60 Middle portion 62 Tip portion 64 Magnet portion 70 Tip unit 72 Tip portion 73 Through hole 74 Cylindrical portion 75 Tip wall portion 76 Cylindrical portion 76a Screw hole 77 Screw 78 Magnetic sensor mounting portion 79 Cover portion 80 Magnetic sensor 100 Mounting plate unit 105 Thread tension applying portion 110 Mounting plate portion 110a Insertion hole 110b Screw hole 110c Insertion hole 110d Screw hole 111 Intermediate plate portion 119 Electromagnet holder unit 120 Electromagnet holder 121 Holder body 122 Top surface portion 124 Front surface portion 125 Through hole 126 Rear surface portion 127 Through hole 128 Right side surface portion 129 Notch portion 129a, 129b Wall surface 130 Bottom surface portion 132 Storage portion 132a Inner circumferential surface 132b Flat surface 132c Inner circumferential surface 132d Flat surface 132K Opening 134 Rod-shaped member 136 Cylindrical member 137 Screw 138a, 138b Screw hole 140 Electromagnet holder 142 Upper surface 144-1 Upper front surface 144-2 Lower front surface 144-2a Lower front surface main body 144-2b Protrusion 145 Through hole 146 Rear surface 147 Recess 148 Left side surface 149 Gap 150 Bottom surface 152 Storage section 152a Inner circumferential surface 152b Flat surface 152c Inner circumferential surface 152d Flat surface 152K Opening 154 Screw 160 Electromagnet 162 Magnetic body 162a Adsorption surface 164 Coil 166 Cover portion 166a Cylindrical portion 166b Circular plate portion 170 Electromagnet 172 Magnetic body 172a Adsorption surface 174 Coil 176 Cover portion 176a Cylindrical portion 176b Circular plate portion 180 Thread presser plate 182 Plate portion 184 Edge portion 190 Thread presser plate 192 Plate portion 194 Edge portion 200 Spring 210 Upper thread guide portion 212 Vertical plate portion 214 Horizontal plate portion 215 Guide hole 215a Cylindrical portion 215b Ring-shaped portion 220, 222, 224, 226, 228 Screw 300 Sewing machine 301 Arm portion 302 Housing portion 302a Mounting hole 302b, 302c screw hole 304 guide member 306 thread take-up lever 308 needle bar 310 shuttle 312 main shaft 314 main shaft motor 316 control circuit 318 storage device 320 input/output device J upper thread P, Q axis U, W spacing

Claims (9)

A thread tension control device for a sewing machine, which is provided upstream of a thread take-up in an upper thread path,
The yarn take-up spring mechanism (5), the yarn tension applying section (105), and the control section (316) are included.
The thread take-up spring mechanism is
A fixing unit (9) that is removably fixed to the sewing machine;
a thread take-up spring (51) provided on a fixed unit, the thread take-up spring having a fixed portion (52) fixed to the fixed unit, and a thread locking unit (57) connected to the fixed portion and rotating relative to the fixed portion, the thread locking unit having a thread locking portion (56) at which an upper thread is locked;
a magnet portion (64) fixed to the thread locking unit;
a magnetic sensor (80) fixed to the fixed unit, the magnetic sensor being disposed opposite the magnet portion when the thread locking unit is not rotating relative to the fixed portion;
having
The thread tension applying unit includes:
an electromagnet holder unit (119) having a first electromagnet holder (120) having a first storage section (132) for storing a first electromagnet, and a second electromagnet holder (140) having a second storage section (152) for storing a second electromagnet, the first electromagnet holder and the second electromagnet holder being provided with a gap between them, an opening (132K) being provided on the second electromagnet holder side of the first storage section, and an opening (152K) being provided on the first electromagnet holder side of the second storage section, the two openings being provided opposite each other;
a first electromagnet (160) having an attraction surface (162a) on a second electromagnet side, the first electromagnet (160) being housed in the first housing section so as to be movable in the left-right direction when the second electromagnet holder side of the first housing section is the left side and the first electromagnet holder side of the second housing section is the right side;
a second electromagnet (170) having an attraction surface (172a) on the first electromagnet side and housed in the second housing section so as to be movable in the left-right direction;
a first thread pressing plate (180) provided between the first electromagnet and the second electromagnet and having a plate-shaped portion (182) facing an attraction surface of the first electromagnet;
a second thread pressing plate (190) provided between the first electromagnet and the second electromagnet and closer to the second electromagnet than the first thread pressing plate, the second thread pressing plate having a plate-shaped portion ( 192 ) facing an attraction surface of the second electromagnet;
A fixing member (110) for removably fixing the electromagnet holder unit to the sewing machine;
having
In the thread take-up spring mechanism, the upper thread is held by the thread holding portion, the thread holding portion is provided on the upper thread path upstream of the thread take-up lever, the thread tension applying portion is provided on the upper thread path upstream of the thread take-up spring mechanism, and the upper thread path is provided between the first thread presser disc and the second thread presser disc,
a control unit for exciting the first electromagnet and the second electromagnet to attract each other when the thread take-up pulls the upper thread, causing the thread hold-down unit to rotate and increasing the distance between the magnet unit and the magnetic sensor so that the value of the magnetic force of the magnet unit detected by the magnetic sensor becomes smaller than a predetermined value; and a control unit for stopping excitation of the first electromagnet and the second electromagnet to cause the first electromagnet and the second electromagnet to be attracted to each other, thereby clamping the upper thread between the plate-shaped portion of the first thread presser plate and the plate-shaped portion of the second thread presser plate, thereby applying tension to the upper thread. On the other hand, when the state in which the thread take-up pulls the upper thread is released, the thread hold-down unit rotates and decreasing the distance between the magnet unit and the magnetic sensor so that the value of the magnetic force of the magnet unit detected by the magnetic sensor becomes equal to or greater than the predetermined value, the control unit stops exciting the first electromagnet and the second electromagnet to release the attraction between the first electromagnet and the second electromagnet, thereby releasing the application of tension to the upper thread. A thread tension control device for a sewing machine, which is provided upstream of a thread take-up in an upper thread path,
The yarn take-up spring mechanism (5), the yarn tension applying section (105), and the control section (316) are included.
The thread take-up spring mechanism is
A fixing unit (9) that is removably fixed to the sewing machine;
a thread take-up spring (51) provided on a fixed unit, the thread take-up spring having a fixed portion (52) fixed to the fixed unit, and a thread locking unit (57) connected to the fixed portion and rotating relative to the fixed portion, the thread locking unit having a thread locking portion (56) at which an upper thread is locked;
a magnet portion (64) fixed to the thread locking unit;
a magnetic sensor (80) fixed to the fixed unit, the magnetic sensor being disposed opposite the magnet portion when the thread locking unit is not rotating relative to the fixed portion;
having
The thread tension applying unit includes:
an electromagnet holder unit (119) having a first electromagnet holder (120) having a first storage section (132) for storing a first electromagnet, and a second electromagnet holder (140) having a second storage section (152) for storing a second electromagnet, the first electromagnet holder and the second electromagnet holder being provided with a gap between them, an opening (132K) being provided on the second electromagnet holder side of the first storage section, and an opening (152K) being provided on the first electromagnet holder side of the second storage section, the two openings being provided opposite each other;
a first electromagnet (160) having an attraction surface (162a) on a second electromagnet side, the first electromagnet (160) being housed in the first housing section so as to be movable in the left-right direction when the second electromagnet holder side of the first housing section is the left side and the first electromagnet holder side of the second housing section is the right side;
a second electromagnet (170) having an attraction surface (172a) on the first electromagnet side and housed in the second housing section so as to be movable in the left-right direction;
a first thread pressing plate (180) provided between the first electromagnet and the second electromagnet and having a plate-shaped portion (182) facing an attraction surface of the first electromagnet;
a second thread pressing plate (190) provided between the first electromagnet and the second electromagnet and closer to the second electromagnet than the first thread pressing plate, the second thread pressing plate having a plate-shaped portion ( 192 ) facing an attraction surface of the second electromagnet;
having
The fixing unit has a plate-shaped portion (110, 111) extending toward the thread tension applying portion, and the electromagnet holder unit is provided on the plate-shaped portion,
In the thread take-up spring mechanism, the upper thread is held by the thread holding portion, the thread holding portion is provided on the upper thread path upstream of the thread take-up lever, the thread tension applying portion is provided on the upper thread path upstream of the thread take-up spring mechanism, and the upper thread path is provided between the first thread presser disc and the second thread presser disc,
a control unit for exciting the first electromagnet and the second electromagnet to attract each other when the thread take-up pulls the upper thread, causing the thread hold-down unit to rotate and increasing the distance between the magnet unit and the magnetic sensor so that the value of the magnetic force of the magnet unit detected by the magnetic sensor becomes smaller than a predetermined value; and a control unit for stopping excitation of the first electromagnet and the second electromagnet to cause the first electromagnet and the second electromagnet to be attracted to each other, thereby clamping the upper thread between the plate-shaped portion of the first thread presser plate and the plate-shaped portion of the second thread presser plate, thereby applying tension to the upper thread. On the other hand, when the state in which the thread take-up pulls the upper thread is released, the thread hold-down unit rotates and the distance between the magnet unit and the magnetic sensor becomes shorter and the value of the magnetic force of the magnet unit detected by the magnetic sensor becomes equal to or greater than the predetermined value, the control unit stops exciting the first electromagnet and the second electromagnet to release the attraction between the first electromagnet and the second electromagnet, thereby releasing the application of tension to the upper thread. The thread tension control device for a sewing machine is provided with a memory device (318) that stores current data that indicates the current values for exciting the first electromagnet and the second electromagnet for each stitch,
3. The thread tension control device for a sewing machine according to claim 1, wherein the control unit excites the first electromagnet and the second electromagnet in accordance with a current value stored in the current data when exciting the first electromagnet and the second electromagnet in each stitch. The fixed unit has a central component (41), a tip portion (72) attached to the central component, and a guide wall portion (30);
The central components are:
A thread take-up spring mounting portion (42) for mounting the thread take-up spring, the thread take-up spring mounting portion having a cylindrical peripheral surface;
a shaft portion (46) provided on the back side of the thread take-up spring mounting portion, the shaft portion having a cylindrical peripheral surface and an outer diameter smaller than the outer diameter of the thread take-up spring mounting portion;
The guide wall portion is provided on the rear side of the shaft portion, has an annular protrusion (34) protruding toward the thread take-up spring mounting portion, and has an outer diameter larger than the outer diameter of the shaft portion;
The tip portion has an inner circumferential surface with an inner diameter larger than the outer diameter of the thread take-up spring mounting portion , and has a cylindrical cover portion (79), and the thread take-up spring mounting portion is provided inside the inner circumferential surface of the cover portion,
The thread take-up spring is formed of a linear member, a fixed portion of the thread take-up spring is fixed to the peripheral surface of the thread take-up spring mounting portion, the thread locking unit has a protruding portion (54) connected to the fixed portion and protruding relative to the peripheral surface of the thread take-up spring mounting portion, the thread locking portion is connected to the tip of the protruding portion, and the magnet portion is attached to the protruding portion,
The magnetic sensor is provided in an end region on the rear side of the cover,
3. The thread tension control device for a sewing machine according to claim 1, wherein the needle thread led from the thread tension applying portion is engaged with the thread engaging portion after coming into contact with the peripheral surface of the shaft portion. The electromagnet holder unit includes a first connecting member (134) that connects the first electromagnet holder and the second electromagnet holder and has a cylindrical outer circumferential surface, and a second connecting member (136) that connects the first electromagnet holder and the second electromagnet holder and has a cylindrical outer circumferential surface, the first connecting member and the second connecting member being provided with the axis of the cylindrical outer circumferential surface extending in the left-right direction,
the first connecting member is provided on a rear surface of the electromagnet holder unit, and the second connecting member is provided on a front surface of the electromagnet holder unit, the first connecting member and the second connecting member being provided at positions facing each other across the first thread presser plate and the second thread presser plate,
3. The thread tension control device for a sewing machine according to claim 1, wherein the upper thread path of the upper thread led from the upstream of the thread tension applying section passes from the first connecting member to the second connecting member, returns to the first connecting member, and then reaches the thread take-up spring mechanism. A thread tension control device for a sewing machine as described in claim 1 or 2, characterized in that the target storage section, which is one of the two storage sections, the first storage section and the second storage section, is provided with a biasing means (200) that biases an electromagnet, which is one of the first electromagnet and the second electromagnet, stored in the target storage section toward the opening side of the target storage section. A thread tension applying device for a sewing machine, which is provided upstream of a thread take-up in an upper thread path,
an electromagnet holder unit (119) having a first electromagnet holder (120) having a first storage section (132) for storing a first electromagnet, and a second electromagnet holder (140) having a second storage section (152) for storing a second electromagnet, the first electromagnet holder and the second electromagnet holder being provided with a gap between them, an opening (132K) being provided on the second electromagnet holder side of the first storage section, and an opening (152K) being provided on the first electromagnet holder side of the second storage section, the two openings being provided opposite each other;
a first electromagnet (160) having an attraction surface (162a) on a second electromagnet side, the first electromagnet (160) being housed in the first housing section so as to be movable in the left-right direction when the second electromagnet holder side of the first housing section is the left side and the first electromagnet holder side of the second housing section is the right side;
a second electromagnet (170) having an attraction surface (172a) on the first electromagnet side and housed in the second housing section so as to be movable in the left-right direction;
a first thread pressing plate (180) provided between the first electromagnet and the second electromagnet;
a second thread presser plate (190) provided between the first electromagnet and the second electromagnet, closer to the second electromagnet than the first thread presser plate, and facing the first thread presser plate;
having
An upper thread path is provided between the first thread presser plate and the second thread presser plate,
A thread tension applying device for a sewing machine, characterized in that a first electromagnet and a second electromagnet are excited to attract each other, thereby clamping the upper thread between the first thread presser plate and the second thread presser plate and applying tension to the upper thread. A thread tension applying device for a sewing machine includes a first connecting member (134) that connects a first electromagnet holder and a second electromagnet holder, the first connecting member having a cylindrical outer circumferential surface, and a second connecting member (136) that connects the first electromagnet holder and the second electromagnet holder, the second connecting member having a cylindrical outer circumferential surface, the first connecting member and the second connecting member being provided with the axis of the cylindrical outer circumferential surface extending in the left-right direction,
the first connecting member is provided on a rear surface of the electromagnet holder unit, and the second connecting member is provided on a front surface of the electromagnet holder unit, the first connecting member and the second connecting member being provided at positions facing each other across the first thread presser plate and the second thread presser plate,
8. The thread tensioning device for a sewing machine according to claim 7, wherein the upper thread path of the upper thread guided from upstream of the thread tensioning section passes from the first connecting member to the second connecting member, then returns to the first connecting member, and then reaches the thread take-up spring mechanism. The thread tensioning device for a sewing machine according to claim 7 or 8, characterized in that the target storage section, which is one of the two storage sections, the first storage section and the second storage section, is provided with a biasing means (200) for biasing the electromagnet, which is either the first electromagnet or the second electromagnet, stored in the target storage section toward the opening side of the target storage section.

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