Sewing machine thread tension control device and sewing machine thread tension applying device

Abstract

To provide a thread tension control device which applies tension by detecting displacement of a thread take-up spring, which can respond to tension application quickly, and which can cut off thread tension application without keeping reverse excitation of an electromagnet.SOLUTION: A thread tension control device 1 includes a thread take-up spring mechanism part 5, and a thread tension application part 105. At the thread take-up mechanism part 5, a thread take-up spring 51 is provided. At the thread take-up spring 51, a thread locking part 56 is provided and a magnet part 64 is provided, and also, a magnetic sensor 80 is provided to face the magnet part 64. At the thread tension application part 105, electromagnets are stored in electromagnet holders 120, 140 respectively, and thread presser trays 180, 190 are provided between the two electromagnets. When a thread take-up lever pulls a needle thread and the magnet part 64 is separated from the magnetic sensor 80, by exciting the electromagnets to suck, tension is applied to a needle thread J between the two thread presser trays.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a device for tensioning the needle thread of a sewing machine. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there exists a thread tension control device for controlling the tension of an upper thread in a sewing machine, as shown in Patent Document 1.

[0003] 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 on 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 for the shuttle fastening 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 to calculate 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.

[0004] 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 attractive action of the movable iron core 10 moves a pair of thread tension discs 8, 9, and tension is applied to the thread between the pair of thread tension discs 8, 9.

[0005] In addition, in the yarn tension adjusting device of Patent Document 2, in a yarn tension adjusting device 2 that adjusts the tension applied to a yarn Y sandwiched between opposing surfaces 211, 221 of 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 electromagnet 25 is connected to a power source so that its magnetic pole can be changed and so that the amount of current flowing therethrough can be changed, and a coil spring 27 is constantly biased to move the first disk 21 closer to the second disk 22. By changing the magnetic pole of the electromagnet 25, attractive and repulsive forces with respect to the polarity of the permanent magnet 24 are obtained, and the attractive and repulsive forces with respect to the permanent magnet 24 can be made variable depending on the amount of current flow. In other words, 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 that of the permanent magnet 24. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-8713 A [Patent Document 2] Patent Publication No. 2020-204106 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the yarn 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 yarn 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 application of thread tension, making it impossible to obtain a high-speed response.

[0008] 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 in a state in which the thread tension disc 8 is in close contact with the thread tension disc 9 and 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 movable core 10 itself to move is short, it takes time until thread tension is applied.

[0009] In the yarn tension adjusting device of Patent Document 2, the response of yarn tension application can be made faster by changing the polarity of the electromagnet 25 to attract or repel it against the permanent magnet 24, but 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 yarn tension, the electromagnet 25 must be continuously reverse-excited so as to repel the permanent magnet 24. In other words, in order to switch between applying yarn tension and cutting off yarn tension, the polarity must be changed while the electromagnet 25 is constantly excited.

[0010] Therefore, an object of the present invention is to provide an upper thread tension control device that can apply upper thread tension by detecting the displacement of a thread take-up spring, that can respond to tension application quickly, and that can cut off the application of thread tension without continuously reverse-exciting an electromagnet. [Means for solving the problem]

[0011] The present invention has been devised to solve the above problems. First, the present invention provides a thread tension control device for a sewing machine, which is provided upstream of the thread take-up lever in the upper thread path, and which has 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 which is connected to the fixed section and rotates relative to the fixed section, and which has a thread locking section (56) at which the upper thread is locked. a magnet section (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 section when the thread locking unit is not rotated relative to the fixed unit. The thread tension imparting section comprises a first electromagnet holder (120) having a first storage section (132) for storing the first electromagnet, and a second electromagnet holder (140) having a second storage section (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, and the two openings are 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, The 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 (180) 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 (182) facing the attracting surface of the second electromagnet. 192and 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 magnetic force of the magnet part detected by the magnetic sensor becomes equal to or greater 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, thereby applying tension to the upper thread. When the state in which the thread take-up lever 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 magnetic force of the magnet part detected by the magnetic sensor becomes equal to or greater than a predetermined value, the magnetic force of the magnet part is released by stopping the excitation of the first electromagnet and the second electromagnet, thereby releasing the attraction between the first electromagnet and the second electromagnet, thereby releasing the application of tension to the upper thread.

[0012] Therefore, when applying yarn tension, it is sufficient to excite the first electromagnet and the second electromagnet so that they are attracted to each other. In particular, by simultaneously exciting the first electromagnet and the second electromagnet, the first electromagnet and the second electromagnet can be quickly attracted to each other, thereby enabling a high-speed response in applying tension.

[0013] Also, when cutting off the application of yarn tension, it is possible to cut off the application of yarn tension without reversely exciting the electromagnets by stopping the supply of current to the first electromagnet and the second electromagnet. Also, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, it is possible to quickly cut off the excitation of the first electromagnet and the second electromagnet, thereby enabling a high-speed response to cut off the tension.

[0014] Furthermore, when no yarn tension is being applied, the current supply to the first electromagnet and the second electromagnet 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 electromagnet and the second electromagnet and to reduce the size of the first electromagnet and the second electromagnet.

[0015] In addition, since the yarn tension is applied by two electromagnets, a large yarn tension can be applied, and as a result, a wide range of yarn tension can be applied, from no yarn tension to the large yarn tension.

[0016] In addition, since the first electromagnet and the second electromagnet are controlled in accordance with 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, it is easy to install on existing sewing machines.

[0017] Furthermore, the thread take-up spring mechanism is provided with a fixing unit that can be removably fixed to the sewing machine, and the thread tension imparting part 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 tension imparting part are formed separately, when installing the thread tension control device to an existing sewing machine, the installation positions of the thread take-up spring mechanism and the thread tension imparting part can be adjusted, making installation to an existing sewing machine easy.

[0018] Secondly, a thread tension control device for a sewing machine is provided upstream of the thread take-up lever in the upper thread path, and includes a thread take-up spring mechanism (5), a thread tension applying section (105), and a control section (316). The thread take-up spring mechanism includes a fixed unit (9) that 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) that is connected to the fixed section and rotates relative to the fixed section, and includes a thread locking section (56) that locks the upper thread. the thread tension applying section 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 applying 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. an electromagnet holder unit (119) in which 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; and a first electromagnet having an attraction surface (162a) on the second electromagnet side, the first electromagnet having an attraction surface (162a) on the second electromagnet side, and the second electromagnet holder unit (119) having a first electromagnet holder side and an opening (152K) on the first electromagnet holder side of the second storage section, the first electromagnet holder side being movable in the left-right direction 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 (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 (180) 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 (182) facing the attracting surface of the second electromagnet. 192and a second thread presser disc (190) having a second thread tensioner (110) and a second thread presser disc (190) having a second thread tensioner (110), the fixed unit having a plate-shaped portion (110, 111) extending toward the thread tensioner, the electromagnet holder unit being provided on the plate-shaped portion, 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 upper thread path being provided between the first thread presser disc and the second thread presser disc, the control unit being configured to control the thread tensioner (110) and the second thread presser disc (190) such that the thread engaging portion (110) is engaged with the second thread tensioner (110), the electromagnet holder unit being provided on the plate-shaped portion, 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 upper thread path being provided between the first thread presser disc and the second thread presser disc, When the value of the magnetic force of the magnet portion becomes smaller than a predetermined value, the first electromagnet and the second electromagnet are excited to attract the first electromagnet and the second electromagnet, 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.

[0019] Therefore, when applying yarn tension, it is sufficient to excite the first electromagnet and the second electromagnet so that they are attracted to each other. In particular, by simultaneously exciting the first electromagnet and the second electromagnet, the first electromagnet and the second electromagnet can be quickly attracted to each other, thereby enabling a high-speed response in applying tension.

[0020] Also, when cutting off the application of yarn tension, it is possible to cut off the application of yarn tension without reversely exciting the electromagnets by stopping the supply of current to the first electromagnet and the second electromagnet. Also, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, it is possible to quickly cut off the excitation of the first electromagnet and the second electromagnet, thereby enabling a high-speed response to cut off the tension.

[0021] Furthermore, when no yarn tension is being applied, the current supply to the first electromagnet and the second electromagnet 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 electromagnet and the second electromagnet and to reduce the size of the first electromagnet and the second electromagnet.

[0022] In addition, since the yarn tension is applied by two electromagnets, a large yarn tension can be applied, and as a result, a wide range of yarn tension can be applied, from no yarn tension to the large yarn tension.

[0023] In addition, since the first electromagnet and the second electromagnet are controlled in accordance with 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, it is easy to install on existing sewing machines.

[0024] Furthermore, the fixed unit has a plate-shaped portion extending toward the thread tension imparting portion, and the electromagnet holder unit is provided on the plate-shaped portion, and the thread take-up spring mechanism and the thread tension imparting portion are formed integrally, 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 imparting portion.

[0025] Thirdly, in the above-mentioned 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.

[0026] Therefore, by providing the current data, the current value when exciting the first electromagnet and the second electromagnet can be adjusted for each stitch, thereby controlling the upper thread tension for each stitch.

[0027] 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 tip portion has an inner circumferential surface with an inner diameter larger than the outer diameter of the thread take-up spring mounting portion. , cylindrical the thread take-up spring is formed of 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 relative to 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 is locked to the thread locking portion after coming into contact with the peripheral surface of the shaft portion.

[0028] Therefore, the shaft is sandwiched between the thread take-up spring device and the guide wall, and the thread take-up spring mounting part and the guide wall 30 are also formed with small diameters, which makes it easier to bring the upper thread into contact with the circumferential surface of the shaft. Also, 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 part, the upper thread can be smoothly transferred even if it comes into contact with the guide wall.

[0029] Fifthly, in the first or second configuration, the electromagnet holder unit has a first connecting member connecting the first electromagnet holder and the second electromagnet holder, a first connecting member (134) having a cylindrical outer peripheral surface, and a second connecting member connecting the first electromagnet holder and the second electromagnet holder, a second connecting member (136) having 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 via the first thread pressure plate and the second thread pressure plate, and the upper thread path of the upper thread guided from the upstream of the thread tension imparting 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.

[0030] Therefore, by utilizing 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.

[0031] In addition, as configuration 5-1, in the above-mentioned fifth configuration, the first connecting member may be provided on the upper surface side of the rear 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.

[0032] Further, sixthly, in the above-mentioned 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.

[0033] Therefore, even when the first electromagnet and the second electromagnet are not excited, the plate-shaped portion of the first thread pressing plate and the plate-shaped portion of the second thread pressing plate are in contact with each other, the first thread pressing plate is in contact with the first electromagnet, and the second thread pressing plate is in contact with the second electromagnet. Therefore, when the first electromagnet and the second electromagnet are excited, tension can be instantly applied to the upper thread, and the response of tension application can be made faster.

[0034] As a configuration 6-1, in the above-mentioned configuration 4, the central component includes a second shaft portion (48) connected to the rear side from the rear end of the shaft portion, the second shaft portion having an outer diameter smaller than the outer diameter of the shaft portion and having 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, and 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. The insertion locking portion may have an insertion locking portion (10) for inserting into and locking into a hole for insertion locking provided in the body, the insertion locking portion having a screw hole into which the second shaft portion is screwed, and an attachment plate portion is provided on the rear side of the guide wall portion, and an insertion locking portion is provided on the rear side of the attachment 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 attachment plate portion, so that the guide wall portion and the attachment plate portion are fixed between the shaft portion and the insertion locking portion.

[0035] As a configuration 6-2, in the above configuration 6-1, the central component has a third shaft portion (44) connected from the front end of the thread take-up spring mounting portion, the tip portion is a cylindrical portion protruding from the front of the cover portion (79) and is provided with 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 from the cylindrical portion and having an outer diameter larger than that of the cylindrical portion, and a magnetic sensor mounting 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 mounting portion.

[0036] Further, a seventh item is a thread tension applying device for a sewing machine provided upstream of a thread take-up in an upper thread path, the 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 are provided at a distance from each other, 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 electromagnet holder unit (119) having two openings opposed to each other, 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 needle threader 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 presser plate (180) provided between the first electromagnet and the second electromagnet, and 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, and an upper thread path is provided between the first thread presser plate and the second thread presser plate, and by exciting the first electromagnet and the second electromagnet to attract each other, the upper thread is sandwiched between the first thread presser plate and the second thread presser plate, and tension is applied to the upper thread.

[0037] Therefore, when applying yarn tension, it is sufficient to excite the first electromagnet and the second electromagnet so that they are attracted to each other. In particular, by simultaneously exciting the first electromagnet and the second electromagnet, the first electromagnet and the second electromagnet can be quickly attracted to each other, thereby enabling a high-speed response in applying tension.

[0038] Also, when cutting off the application of yarn tension, it is possible to cut off the application of yarn tension without reversely exciting the electromagnets by stopping the supply of current to the first electromagnet and the second electromagnet. Also, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, it is possible to quickly cut off the excitation of the first electromagnet and the second electromagnet, thereby enabling a high-speed response to cut off the tension.

[0039] Furthermore, when no yarn tension is being applied, the current supply to the first electromagnet and the second electromagnet 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 electromagnet and the second electromagnet and to reduce the size of the first electromagnet and the second electromagnet.

[0040] In addition, since the yarn tension is applied by two electromagnets, a large yarn tension can be applied, and as a result, a wide range of yarn tension can be applied, from no yarn tension to the large yarn tension.

[0041] In an eighth aspect, in the seventh aspect, the thread tension applying device for a sewing machine has a first connecting member connecting the first electromagnet holder and the second electromagnet holder, the first connecting member (134) having a cylindrical outer circumferential surface, and a second connecting member connecting the first electromagnet holder and the second electromagnet holder, the second connecting member (136) having 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 via the first thread pressure plate and the second thread pressure plate, and the upper thread path of the upper thread guided from the upstream of the thread tension applying portion 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.

[0042] Therefore, by utilizing 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.

[0043] A 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) 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.

[0044] Therefore, even when the first electromagnet and the second electromagnet are not excited, the plate-shaped portion of the first thread pressing plate and the plate-shaped portion of the second thread pressing plate are in contact with each other, the first thread pressing plate is in contact with the first electromagnet, and the second thread pressing plate is in contact with the second electromagnet. Therefore, when the first electromagnet and the second electromagnet are excited, tension can be instantly applied to the upper thread, and the response of tension application can be made faster. Effect of the Invention

[0045] According to the thread tension control device for a sewing machine and the thread tension applying device for a sewing machine based on the present invention, when applying thread tension, it is sufficient to excite the first electromagnet and the second electromagnet so that the first electromagnet and the second electromagnet 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 quickly attracted to each other, thereby enabling a high-speed response in applying tension.

[0046] Also, when cutting off the application of yarn tension, it is possible to cut off the application of yarn tension without reversely exciting the electromagnets by stopping the supply of current to the first electromagnet and the second electromagnet. Also, by simultaneously stopping the supply of current to the first electromagnet and the second electromagnet, it is possible to quickly cut off the excitation of the first electromagnet and the second electromagnet, thereby enabling a high-speed response to cut off the tension.

[0047] Furthermore, when no yarn tension is being applied, the current supply to the first electromagnet and the second electromagnet 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 electromagnet and the second electromagnet and to reduce the size of the first electromagnet and the second electromagnet.

[0048] In addition, since the yarn tension is applied by two electromagnets, a large yarn tension can be applied, and as a result, a wide range of yarn tension can be applied, from no yarn tension to the large yarn tension.

[0049] In addition, according to the thread tension control device for a sewing machine based on the present invention, the first electromagnet and the second electromagnet are controlled in accordance with 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, so that it is easy to install it on an existing sewing machine. [Brief description of the drawings]

[0050] [Figure 1] 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. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view of a main part of the thread take-up spring mechanism. [Diagram 5] FIG. [Figure 6] FIG. 4 is a perspective view of the thread tension imparting portion as seen from the left side. [Figure 7]FIG. 4 is a perspective view of the thread tension imparting portion as seen from the right side. [Figure 8] FIG. 2 is a side view showing a state in which the yarn tension control device is used. [Figure 9] FIG. 4 is a cross-sectional view showing a state in which the thread tension imparting portion is used. [Figure 10] FIG. 2 is a front view showing a state in which the yarn tension control device is used. [Figure 11] FIG. 2 is an explanatory diagram showing a configuration of a sewing machine. [Figure 12] FIG. 2 is an explanatory diagram illustrating a configuration of embroidery data. [Figure 13] FIG. 4 is an explanatory diagram showing a configuration of current data. [Figure 14] FIG. 4 is an explanatory diagram showing a configuration of spindle data; [Figure 15] FIG. [Figure 16] 4 is a flowchart showing the operation of the yarn tension control device. [Figure 17] FIG. 4 is a front view showing a yarn tension control device of a first modified example. [Figure 18] FIG. 2 is a perspective view showing a yarn tension control device of a first modified example. [Figure 19] FIG. 2 is an exploded perspective view showing a yarn tension control device of a first modified example. [Figure 20] FIG. 11 is a front view showing a yarn tension control device of a second modified example. [Figure 21] FIG. 13 is a front view showing a yarn tension control device of a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] In the present invention, the objective of providing an upper thread tension control device that can apply upper thread tension by detecting the displacement of a thread take-up spring, can respond quickly to tension application, and can cut off application of thread tension without continuously reverse-exciting an electromagnet, is achieved in the following manner.

[0052] A thread tension control device 1 as a thread tension control device 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 imparting unit 105, and a control circuit 316, and the thread take-up spring mechanism 5 is provided below the thread tension imparting unit 105.

[0053] 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 being inserted and attached 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 on the tip unit 70. The insertion locking portion 10, the mounting plate portion 20, the guide wall portion 30, the central component portion 41 of the central component unit, and the tip unit 70 constitute a fixed unit 9 which is detachably fixed to the sewing machine.

[0054] Here, the insertion locking portion 10 has a substantially circular tubular shape and includes a cylindrical tubular portion 12, an annular portion 14 provided on the front side of the tubular portion 12, and a locking portion 16 provided on the back side of the tubular portion 12, the annular portion 14 has a plate-like ring shape, and the locking portion 16 has a shape in which both ends of the plate-like ring are cut away and has a plate shape surrounded by opposing arc-shaped sides and parallel straight sides, and the diameters of the annular portion 14 and the arc-shaped sides of the locking portion 16 are formed larger than the diameter of the tubular portion 12, and by inserting the insertion locking portion 10 into an attachment hole 302a (see Figure 8) provided in the housing portion 302 and then rotating it, the locking portion 16 engages with the attachment hole 302a, and the thread take-up spring mechanism portion 5 is attached to the housing portion 302.

[0055] 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 later).

[0056] The mounting plate 20 is in the form of a plate having a circular outer shape, with the front and rear surfaces being flat, and a circular through hole 21 provided in the center, with the diameter of the through hole 21 being 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.

[0057] The guide wall 30 has an annular convex shape and a shape that 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 an annular 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 rear side. The guide wall 30 is provided on the rear side of the shaft portion 46 and has an outer diameter (diameter) larger than the outer diameter (diameter) of the shaft portion 46.

[0058] 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 substantially frustum shaped. The front surface of the convex portion 36 is perpendicular to the axis P (see FIG. 3).

[0059] The guide wall 30 is a member that comes into contact with the upper thread J that is guided in contact with the circumferential surface of the shaft portion 46 (described later). By bringing the upper thread into contact with the guide wall 30, the position of the upper thread in the front-rear direction (the Y1-Y2 direction (the direction of the axis P) in FIG. 3, the left-right direction in FIG. 4) can be stabilized. In particular, as shown in FIG. 8, after the upper thread guided from the thread tension imparting portion 105 comes into contact with the shaft portion 46 at approximately the center position of the shaft portion 46 in the front-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 locating the upper thread as closer to the guide wall portion 30 as possible when it is in contact with the shaft portion 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, since the annular protrusion 34 of the guide wall portion 30 protrudes to approximately the center position in the front-to-rear direction of the shaft portion 46 (left-to-right direction in FIG. 4) as shown in FIG. 4, the upper thread can be positioned as approximately in the center as possible in the front-to-rear direction of the shaft portion 46.

[0060] 4 is a cross-sectional view of the essential parts showing members other than the magnetic sensor attachment portion 78 and the magnetic sensor 80. FIG.

[0061] Furthermore, when the upper thread J comes into contact with the guide wall portion 30, it comes into contact with the convex portion 36. However, since the convex portion 36 is provided at the end portion on the front side of the annular convex portion 34 and the area of ​​the convex portion 36 is formed 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 portion 30, the upper thread J can be smoothly transferred to the balance 306 side.

[0062] 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.

[0063] The central component unit 40 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.

[0064] The central component 41 has a cylindrical thread take-up spring mounting portion 42, an axle portion 44 connected to the front surface of the thread take-up spring mounting portion 42, an axle portion 46 connected to the rear surface of the thread take-up spring mounting portion 42, and an axle portion 48 connected to the rear surface of the axle portion 46.

[0065] The thread take-up spring attachment portion 42 is cylindrical in shape, with the front and rear surfaces being flat, that is, the thread take-up spring attachment portion 42 has a cylindrical peripheral surface.

[0066] In addition, the shaft portion (third shaft portion) 44 is cylindrical (i.e., has a cylindrical circumferential surface), and the diameter of the shaft portion 44 is formed 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.

[0067] 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 5 is assembled, the rear surface of the shaft 46 is in contact with the front surface of the central part 32.

[0068] The length of the shaft portion 46 in the axial direction (front-to-back direction) (Y1-Y2 direction (direction of axis P) in Figure 3) is longer than the axial length of the inner inclined portion 35, thereby providing a gap W (see Figure 8) 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.

[0069] The shaft portion 46 is sandwiched between the thread take-up spring attachment portion 42 and the guide wall portion 30, and is formed with a smaller diameter than the thread take-up spring attachment 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 forms the upper thread path.

[0070] The shaft portion (second shaft portion) 48 is generally cylindrical, with the tip of the rear side of the cylinder tapered (i.e., truncated cone). That is, 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.

[0071] When the shaft portion 48 is screwed into the insertion locking portion 10 and fastened, the attachment plate portion 20 and the guide wall portion 30 are sandwiched and fixed between the shaft portion 46 and the insertion locking portion 10 .

[0072] The thread take-up spring mounting portion 42 and the shaft portions 44, 46, 48 are aligned with each other.

[0073] The thread take-up spring unit 50 also has a thread take-up spring 51 formed of a linear member, and a magnet portion 64 attached to the thread take-up spring 51.

[0074] The thread take-up spring 51 has a winding portion 52 wound around the thread take-up spring attachment portion 42 and fixed to the thread take-up spring attachment portion 42, a protrusion 54 connected to the end of the winding portion 52, and a thread locking portion 56 connected to the tip of the protrusion 54. The thread locking portion 56 and the protrusion 54 form a thread locking unit 57.

[0075] The winding part 52 is wound circumferentially around the outer circumferential surface of the thread take-up spring attachment part 42, and one end of the winding part 52 (the end opposite the protrusion 54) is fixed to the thread take-up spring attachment part 42. In other words, the winding part 52 is fixed to the circumferential surface of the thread take-up spring attachment part 42 by, for example, inserting the end into a hole provided in the surface of the thread take-up spring attachment part 42. The winding part 52 corresponds to a fixed part fixed to the fixing unit 9.

[0076] The protrusion 54 is bent from the end of the winding portion 52 and has a substantially straight shape, and is formed to protrude relative to the outer peripheral surface of the thread take-up spring mounting portion 42 so as to move away from the outer peripheral surface as it moves from the base end side, which is the winding portion 52 side, to the tip end side, which is the thread locking portion 56 side.

[0077] 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 the tip end 62 are substantially linear, and 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 the tip end 62 are substantially parallel with a gap therebetween. The base end 58 and the tip end 62 are disposed on the same imaginary plane, which is parallel to the axis P, and the direction of the base end 58 and the tip end 62 is substantially perpendicular to the axis P.

[0078] The axial position of the thread locking portion 56 is a position where the range of the distance W is included in the range of the distance U (see FIG. 8) between the base end 58 and the tip end 62, and preferably, the midpoint of the distance W in the axial direction (a position equidistant from one end and the other end within the range of the distance W) approximately coincides with the midpoint of the distance U in the axial direction (a position equidistant from one end and the other end within the range of the distance U).

[0079] The upper thread J passes through the inside of the thread locking portion 56 , and when the upper thread J is pulled by the thread take-up 306 , the upper thread J is locked to the intermediate portion 60 and the thread locking unit 57 rotates relative to the winding portion 52 .

[0080] The magnet part 64 is a tubular (specifically, cylindrical) permanent magnet having a through hole in the center, and the magnet part 64 is fixed to the protruding part 54 with the protruding part 54 inserted through the through hole. The direction of magnetization is arbitrary as long as the magnetic sensor 80 can detect magnetism. For example, one side is an N pole and the other is an S pole through a boundary surface perpendicular to the axis of the through hole. In other words, one side is an N pole and the other is an S pole through the center in the axial direction of the through hole. In that case, the positions of the N pole and the S pole may be such that the N pole is on the tip side of the protruding part 54, or the S pole is on the tip side of the protruding part 54.

[0081] The tip unit 70 has a cylindrical tip portion 72 , a screw 77 , and a magnetic sensor attachment portion 78 provided on the outer circumferential surface of the tip portion 72 .

[0082] 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 protruding 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. The outer diameter of the tubular portion 76 is formed smaller than the outer diameter of the tubular portion 74.

[0083] Here, the inner diameter of the tubular portion 74 is made larger than the outer diameter of the thread take-up spring mounting portion 42 and is formed to a size that allows the thread take-up spring mounting portion 42 with the winding portion 52 attached to be positioned therein. When the tip unit 70 is attached to the central configuration unit 40, a gap is formed between the inner surface of the tubular portion 74 and the outer surface of the thread take-up spring mounting portion 42, as shown in Figure 4.

[0084] Further, a screw hole 76a is formed in the cylindrical portion 76 in a direction 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.

[0085] Moreover, the magnetic sensor mounting portion 78 has a substantially rectangular parallelepiped shape and is fixed to the outer circumferential surface of the cylindrical portion 74, and is formed so as to protrude toward the rear side beyond the end portion on the rear side of the cylindrical portion 74. In other words, the magnetic sensor 80 is fixed to the side surface of the magnetic sensor mounting portion 78, but the magnetic sensor mounting portion 78 protrudes toward the rear side beyond 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.

[0086] The cylindrical portion 74 and the magnetic sensor attachment portion 78 constitute a "generally cylindrical cover portion 79 having an inner circumferential surface with an inner diameter larger than the outer diameter of the thread take-up spring attachment portion," and as shown in Figure 4 etc., 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 circumferential surface of the cover portion 79. To ensure space for the winding portion 52, a gap is provided between the inner circumferential surface of the cover portion 79 and the outer circumferential surface of the thread take-up spring attachment portion 42.

[0087] Moreover, the magnetic sensor 80 is fixed to the side surface of the magnetic sensor attachment portion 78, and specifically, is provided in an end region on the rear side of the side surface of the magnetic sensor attachment portion 78 (i.e., a region of the magnetic sensor attachment portion 78 protruding from the end portion on the rear side of the cylindrical portion 74 to the rear side). As a result, when the tip unit 70 is attached to the central configuration portion 41, as shown in Figs. 4 and 8, the position of the axial direction (direction of axis P) of the magnetic sensor 80 and the position of the axial direction (direction of axis P) of the magnet portion 64 approximately coincide with each other, and the magnet portion 64 is in close proximity to the magnetic sensor 80. In other words, when the thread locking unit 57 is not rotated relative to the winding portion 52, the magnetic sensor 80 is provided facing the magnet portion 64. Since the protrusion 54 and the thread locking portion 56 in the thread take-up spring unit 50 are located closer to the rear side than the rear end of the tubular portion 74, 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. Furthermore, 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.

[0088] In addition, the cover portion 79 is formed by the cylindrical portion 74 and the magnetic sensor mounting portion 78, and the magnetic sensor 80 is provided in the end region on the rear side of the side surface of the magnetic sensor mounting portion 78, so it can be said that the magnetic sensor 80 is provided in the end region on the rear side of the cover portion 79.

[0089] When the thread take-up spring mechanism 5 is assembled, the insertion locking portion 10 is fixed to the shaft portion 48 by screwing the shaft portion 48 into the screw hole 11 of the insertion locking portion 10 and tightening it, and the guide wall portion 30 and the mounting plate portion 20 are pressed against the insertion locking portion 10 by the shaft portion 46 and fixed thereto. Furthermore, the tip unit 70 is fixed to the shaft portion 44 by inserting the shaft portion 44 into the through hole 73 and fixing it with a screw 77.

[0090] As described above, since the fixed unit 9 is formed by 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, the thread take-up spring 51 and the magnetic sensor 80 can be said to be provided in the fixed unit.

[0091] The thread take-up spring mechanism 5 is configured as described above, and the upper thread J conveyed from the thread tension imparting 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 portion 56 and reaches the balance 306 via the guide member 304. When the balance 306 rises and pulls the upper thread J, the thread locking portion 56 rotates downward, and the downward rotation of the thread locking portion 56 also rotates the protruding portion 54 (i.e., the entire thread locking unit 57 rotates), causing the magnet portion 64 to move away from the magnetic sensor 80. When the magnet portion 64 moves away from the magnetic sensor 80, the magnetic force detected by the magnetic sensor 80 becomes weaker.

[0092] 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 a 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 this does not interfere with the rotation of the thread locking portion 56. Examples of non-magnetic materials include aluminum and stainless steel, and synthetic resin may be used as long as there is no problem with strength.

[0093] 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 housing section 302 of arm section 301 of sewing machine 300, an electromagnet holder 120 for storing electromagnet 160, a rod-shaped member (first connecting member) 134, a tubular member (second connecting member) 136, an electromagnet holder 140 for storing electromagnet 170, electromagnet 160, electromagnet 170, thread pressing discs 180, 190 provided between electromagnet 160 and electromagnet 170, a spring 200 provided between electromagnet 170 and electromagnet holder 140, and an upper thread guide section 210. Incidentally, electromagnet holder unit 119 is configured by electromagnet holder 120, rod-shaped member 134, cylindrical member 136, electromagnet holder 140, and screws 137 and 154 (described later).

[0094] The mounting plate portion (fixing member) 110 has a vertically elongated rectangular plate shape, and the upper region of the mounting plate portion 110 is provided with an insertion hole 110a for inserting a screw for attaching the upper thread guide portion 210 to the housing portion 302, and a screw hole 110b for screwing in a screw for attaching the upper thread guide portion 210, the lower region is provided with an insertion hole 110c for inserting a screw for attachment to the housing portion 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.

[0095] The electromagnet holder (first electromagnet holder) 120 is a holder in which a storage section (first storage section) 132 for storing an electromagnet 160 is open on the left side surface side (X1 side), and has a holder main body 121. The holder main body 121 has an upper surface portion 122, a front surface portion 124 connected downward from an end portion of the front side (Y1 side) of the upper surface portion 122, a back surface portion 126 connected downward from an end portion of the back side (Y2 side) of the upper surface portion 122, and an end portion of the right side surface side (X2 side) of the upper surface portion 122 and an end portion of the right side surface side of the front surface portion 124. and a right side portion 128 connected to the right side end portion of the front portion 124, the lower end portion 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.

[0096] The bottom surface portion 130 has a band-shaped cutout portion 129 formed from the end portion on the left side surface side toward the right side surface side, and a storage portion 132 is provided above the cutout portion 129.

[0097] The storage section 132 is a storage section whose end region on the opening 132K side is formed with a larger diameter than other regions, 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.

[0098] The storage main body 132-1 is a space surrounded by an inner circumferential surface 132a along the cylindrical circumferential surface and a flat surface 132b on the right side surface side connected to the inner circumferential surface 132a, and the diameter of the inner circumferential surface 132a is formed larger than the outer diameter of the electromagnet 160 so that the electromagnet 160 can be stored therein, and is formed smaller than the outer diameter of the thread pressing disc 180. When the thread tension imparting part 105 is in an assembled state, the electromagnet 160 is stored in the storage main body 132-1.

[0099] The large diameter portion 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 disc 180 so that the thread presser disc 180 can be accommodated therein. When the thread tension imparting part 105 is in an assembled state, the thread presser disc 180 is disposed in the large diameter portion 132-2. The flat surface 132d is also connected to the inner circumferential surface 132a.

[0100] In addition, the axial length (direction of axis Q) of storage section 132 (the sum of the axial length of inner surface 132a and the axial length of inner surface 132c) is approximately the same as the axial length of electromagnet 160, but may be longer than the axial length of electromagnet 160.

[0101] The axial length of the large diameter portion 132-2 (the length of the inner peripheral surface 132c) is substantially the same as the thickness of the thread presser disc 180 or is longer than the thickness of the thread presser disc 180.

[0102] A pair of wall surfaces 129a, 129b that form the cutout portion 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 end of the wall surfaces 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 portion 132 has an opening 132K on the electromagnet holder 140 side.

[0103] A through hole 125 for inserting a cylindrical member 136 is provided at an end portion on the bottom side (Z1 side) 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 an end portion on the back side 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.

[0104] Moreover, rod-shaped member 134 is a rod-shaped member having a cylindrical outer circumferential surface, and connects electromagnet holder 120 and electromagnet holder 140. Rod-shaped member 134 is provided with the axis of the cylindrical outer circumferential surface in the left-right direction. Rod-shaped member 134 is provided on the upper surface side (Z2 side) of the back portion of electromagnet holders 120, 140.

[0105] Further, cylindrical member 136 is a cylindrical member having a cylindrical outer circumferential surface, and connects electromagnet holder 120 and electromagnet holder 140. Cylindrical member 136 is provided with the axis of the cylindrical outer circumferential surface in the left-right direction. Cylindrical member 136 is provided on the bottom surface side in the front portion of electromagnet holders 120, 140. Wiring of electromagnet 170 is inserted into cylindrical member 136.

[0106] That is, the rod-shaped member 134 and the cylindrical member 136 are provided at positions facing each other via the thread pressing disks 180, 190. Although it has been described above that the rod-shaped member 134 is provided on the upper surface side of the rear portion of the electromagnet holders 120, 140 and the cylindrical member 136 is provided on the bottom surface side of the front portion of the electromagnet holders 120, 140, it is only necessary that the rod-shaped member 134 is provided on the rear portion of the electromagnet holders 120, 140 and the cylindrical member 136 is provided on the front portion of the electromagnet holders 120, 140, and that the rod-shaped member 134 and the cylindrical member 136 are provided at positions facing each other via the thread pressing disks 180, 190.

[0107] By arranging the rod-shaped member 134 and the tubular member 136 in positions facing each other with the thread pressure disks 180, 190 interposed therebetween, an upper thread path can be provided between the thread pressure disks 180 and 190 by utilizing the rod-shaped member 134 and the tubular member 136. In particular, by arranging the upper thread path so that it runs from the rod-shaped member 134 to the tubular member 136 and then returns to the rod-shaped member 134, as shown in FIG. 9, two upper thread paths can be provided between the thread pressure disks 180 and 190, and tension can be efficiently applied to the upper thread.

[0108] Further, the rear surface of electromagnet holder 120 is provided with screw holes 138a, 138b so that screws 226, 228 for attaching electromagnet holder 120 to mounting plate portion 110 can be screwed therein.

[0109] Further, electromagnet holder (second electromagnet holder) 140 is a holder in which storage section (second storage section) 152 for storing electromagnet 170 is open on the right side, and includes upper surface section 142, upper front surface section 144-1 connected downward from the end portion on the front side of upper surface section 142, rear surface section 146 connected downward from the end portion on the rear side of upper surface section 142, left side surface section 148 connected from the end portion on the left side side of upper surface section 142, the end portion on the left side side of upper front surface section 144-1, and the end portion on the left side side of rear surface section 146, and a lower end portion of rear surface section 146 and the left side The upper surface 142 has a bottom surface 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 upper 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 upper surface portion 142, the right side surface of the upper 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.

[0110] 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 connected to the right end of the lower front body 144-2a and protruding to the front side, the lower front body 144-2a being connected to the left side surface part 148 and the bottom surface part 150, and the protrusion 144-2b being connected to the bottom surface part 150. A gap 149 is formed between the lower end of the upper front part 144-1 and the upper end of the lower front part 144-2, and a storage part 152 is provided on the rear side of the gap 149.

[0111] The storage section 152 is a storage section whose end region on the opening 152K side is formed with a larger diameter than other regions, 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.

[0112] The storage main body 152-1 is a space surrounded by an inner circumferential surface 152a along the cylindrical circumferential surface and a flat surface 152b on the left side surface side connected to the inner circumferential surface 152a, and the diameter of the inner circumferential surface 152a is formed larger than the outer diameter of the electromagnet 170 so that the electromagnet 170 can be stored therein, and is formed smaller than the outer diameter of the thread pressing disc 190. When the thread tension imparting part 105 is in an assembled state, the electromagnet 170 is stored in the storage main body 152-1.

[0113] The large diameter portion 152-2 is a space surrounded by an inner circumferential surface 152c along the cylindrical circumferential surface and an annular flat surface 152d continuing from the inner circumferential surface 152c, and the diameter of the inner circumferential surface 152c is formed larger than the outer diameter of the thread presser disc 190 so that the thread presser disc 190 can be accommodated therein. When the thread tension imparting part 105 is in an assembled state, the thread presser disc 190 is disposed in the large diameter portion 152-2. The flat surface 152d is also continuing from the inner circumferential surface 152a.

[0114] In addition, the axial length (direction of axis Q) of storage section 152 (the sum of the axial length of inner surface 152a and the axial length of inner surface 152c) is longer than the axial length of storage section 132 by the amount that allows spring 200 to be stored therein, and is longer than the axial length of electromagnet 170.

[0115] The axial length of the large diameter portion 152-2 (the length of the inner peripheral surface 152c) is substantially the same as the thickness of the thread presser disc 190 or is longer than the thickness of the thread presser disc 190.

[0116] The inner circumferential surfaces 152a, 152c have front ends to which the lower surface of the upper front portion 144-1 and the upper surface of the lower front portion 144-2 are connected. The center lines of the inner circumferential surfaces 152a, 152c are oriented in the direction of the axis Q.

[0117] Storage section 152 has an opening 152K on the side of electromagnet holder 120. Note that electromagnet holder 120 and electromagnet holder 140 are provided with a gap between them, and opening 132K and opening 152K face each other with a gap between them.

[0118] In addition, a recess 147 is provided in the left-right direction in the area from the end portion on the rear side of upper surface portion 142 to the end portion on the upper side of rear surface portion 146, and recess 147 forms a part of the inner circumferential surface of the cylindrical shape, so that cylindrical rod-shaped member 134 fits into recess 147.

[0119] Further, in the protruding portion 144-2b, a through hole 145 that presents an inner peripheral surface of the cylindrical shape is formed in the left-right direction, and the cylindrical tubular member 136 can be inserted therethrough. Note that, between the lower surface of the protruding portion 144-2b and the through hole 145, a screw hole for screwing a screw 154 is provided.

[0120] The electromagnet (first electromagnet) 160 has a magnetic body 162, a coil 164 wound around the magnetic body 162, and a cover portion 166 for housing the magnetic body 162 and the coil 164. The magnetic body 162 has a substantially cylindrical shape, and also has a substantially 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 is oriented in the direction of the axis Q.

[0121] In addition, the axial length (direction of axis Q) of electromagnet 160 is approximately the same as the axial length of storage section 132 (the sum of the axial length of inner surface 132a and the axial length of inner surface 132c), but may be shorter than the axial length of storage section 132.

[0122] 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 for housing the magnetic body 172 and the coil 174. The magnetic body 172 has a substantially cylindrical shape, and also has a substantially cylindrical shape in the state of the magnetic body 172 and the coil 174. The cover portion 176 has a shape in which one end of the cylindrical shape is closed by a circular plate portion, and the cover portion 176 has a cylindrical tubular portion 176a and a circular plate portion 176b. In the electromagnet 170, the exposed surface of the magnetic body 172 (the exposed surface on the flat right side surface) becomes the attraction surface 172a. In order to allow the electromagnet 170 to move left and right within the storage portion 152, the diameter of the cover portion 176 is formed to be slightly smaller than the diameter of the inner circumferential surface 152a of the storage portion 152 of the electromagnet holder 140. The center line of the cylindrical portion 176a is oriented in the direction of the axis Q.

[0123] Moreover, the thread pressing plate (first thread pressing plate) 180 has a substantially dish-like shape and includes 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 substantially 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.

[0124] The thread presser plate (second thread presser plate) 190 has the same configuration as the thread presser plate 180, and has a generally dish-like shape, a 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 with increasing distance 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 surface on the right side of the electromagnet 170.

[0125] Moreover, spring 200 is a coil spring, and is provided at a position between left side surface portion 148 and electromagnet 170 with the axis (center line) of spring 200 facing the direction of axis Q, and specifically, one end of spring 200 is fixed to the inner surface of left side surface portion 148, i.e., flat surface 152b of storage portion 152, and the other end is in contact with circular plate portion 176b of cover portion 176, and spring 200 urges electromagnet 170 toward the right side surface. In other words, storage portion 152 as a target storage portion is provided with spring (urging means) 200 that urges electromagnet 170 toward opening portion 152K of storage portion 152.

[0126] The thread presser discs 180, 190 are biased by a spring 200. Even when neither the electromagnet 160 nor the electromagnet 170 is excited, the plate-shaped portion 182 of the thread presser disc 180 and the plate-shaped portion 192 of the thread presser disc 190 are in contact with each other, the thread presser disc 180 is in contact with the electromagnet 160, and the thread presser disc 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 a faster response in tension application can be achieved. 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 from the thread tension imparting 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 portion 132-2, and a part of the thread presser disc 190 is located within the large diameter portion 152-2, so that the thread presser discs 180, 190 do not fall off from the thread tension imparting section 105 even when the electromagnets 160, 170 are not excited. The biasing force of the spring 200 may be a minimum biasing force that allows the thread presser disc 180 and the thread presser disc 190 to come into contact with each other.

[0127] In addition, the upper thread guide portion 210 is a member for guiding the upper thread J sent from the wound thread to a position between the thread pressing plate 180 and the thread pressing plate 190, and the upper thread guide portion 210 has a vertical plate portion 212 and a horizontal plate portion 214 fixed to the lower end of the vertical plate portion 212.

[0128] The vertical plate portion 212 has a rectangular plate shape, and its horizontal length is formed to be the same as the horizontal length of the mounting plate portion 110, and its vertical length is shorter than the length from the upper end of the mounting plate portion 110 to the upper surface of the electromagnet holder 120.

[0129] The horizontal plate portion 214 is formed in a horizontal direction and perpendicular to the vertical plate portion 212. The horizontal plate portion 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 portion 214. However, in order to position the guide hole 215 near the positions of the thread presser discs 180 and 190 in the left-right direction, the horizontal plate portion 214 protrudes to the left side further than the end portion of the left side side of the vertical plate portion 212. The end portion of the right side side of the horizontal plate portion 214 coincides with the end portion of the right side side of the vertical plate portion 212. In other words, the horizontal plate portion 214 is formed longer in the horizontal direction than the vertical plate portion 212 by the amount that it protrudes to the left side further than the vertical plate portion 212. The horizontal plate portion 214 is provided with a hole portion for arranging the guide hole 215.

[0130] 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 being 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.

[0131] When the upper thread guide portion 210 is attached to the attachment plate portion 110, the pair of screws 222 are screwed into the screw holes 110b.

[0132] Incidentally, among the components constituting the thread tension imparting unit 105, the components other than the electromagnets 160, 170 (except for the cover portions 166, 176) (specifically, the mounting plate portion 110, the electromagnet holder unit 119 (electromagnet holders 120, 140, rod-shaped member 134, cylindrical member 136, etc.), thread presser discs 180, 190, spring 200, and upper thread guide portion 210) are made of a non-magnetic material. In other words, the above-mentioned components are made of a non-magnetic material so as not to interfere with the magnetic bodies 162, 172 attracting each other when the electromagnets 160, 170 are excited. Incidentally, examples of the non-magnetic material include aluminum and stainless steel, and synthetic resin may be used as long as there is no problem with strength.

[0133] In the assembled state of the thread tension applying unit 105, the electromagnet 160 is accommodated in the accommodation portion 132 of the electromagnet holder 120, the electromagnet 170 is accommodated in the accommodation portion 152 of the electromagnet holder 140, the spring 200 is provided between the left side surface portion 148 and the cover portion 176 of the electromagnet holder 140, and the thread pressing plates 180, 190 are provided between the electromagnets 160 and 170. In this state, 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. Also, the upper thread guide portion 210 is attached to the mounting plate portion 110.

[0134] In addition, 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 presser discs 180 and 190), and in the thread presser discs 180 and 190, the outer faces of the plate-shaped parts 182 and 192 (the faces opposite the edge side in each thread presser disc) 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.

[0135] When the thread tension applying unit 105 is attached to the housing part 302, a pair of screws 220 are inserted into the insertion holes 110a and screwed into the screw holes 302b of the housing part 302, and a pair of screws 224 are inserted into the insertion holes 110c and screwed into the screw holes 302c of the housing part 302.

[0136] Moreover, in a state where the thread tension imparting unit 105 is attached to the housing 302, a hole is provided on the right side surface of the electromagnet holder 120 in the housing 302 for leading out the wiring to the electromagnets 160, 170, and the wiring to the electromagnet 160 runs from the right side surface of the electromagnet holder 120 to the bottom side of the electromagnet holder 120 and reaches the electromagnet 160 via the notch 129. Moreover, the wiring to the electromagnet 170 runs from the right side surface of the electromagnet holder 120 to the cylindrical member 136, the wiring enters the cylindrical member 136 from the end on the right side surface of the cylindrical member 136 and is led out from the end on the left side surface of the cylindrical member 136, and the wiring led out from the end on the left side surface of the cylindrical member 136 reaches the electromagnet 170 in the storage unit 152 via the gap 149 in the electromagnet holder 140.

[0137] In the thread tension imparting section 105, the electromagnets 160 and 170 are excited so that the electromagnets 160 and 170 are attracted to each other, whereby the magnetic bodies 162 and 172 are attracted to each other, and 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, and 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. In this sandwiched state, the upper thread J is pulled by the balance 306, thereby applying tension to the upper thread J.

[0138] The relative positions of the thread take-up spring mechanism 5 and the thread tension applying unit 105 when they are attached to the housing 302 of the arm 301 are such that the upper thread J that passes between the thread presser disc 180 and the thread presser disc 190 comes into contact with the circumferential surface of the shaft 46 is engaged with the thread engaging portion 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 presser discs 180 and 190 coincides with the vertical tangent at a position on the right side of the circumferential surface of the shaft 46.

[0139] 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 made to contact the end on the right side of the shaft portion 46, and the upper thread J guided vertically between the thread pressing plate 180 and the thread pressing plate 190 contacts the circumferential surface of the shaft portion 46 without changing its vertical direction, and after contacting the circumferential surface of the shaft portion 46, curves along the circumferential surface of the shaft portion 46 to the left side, and then leaves the circumferential surface of the shaft portion 46 to be engaged with the thread engaging portion 56.

[0140] 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 at a position (where the boundary line and the tangent line coincide), the upper thread J led out from the thread tension imparting unit 105 is smoothly led to the thread take-up spring mechanism 5, and no unnecessary load is applied to 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 ends of the thread presser discs 180, 190 and bend at the lower ends, which may cause a load to be applied to the upper thread J, or the upper thread J may come into contact with the lower ends of the electromagnet holders 120, 140 and cause a load to be applied to the upper thread J. However, if the boundary line and the tangent line coincide at a position, there is no such risk.

[0141] As shown in Figures 1 and 10, the thread take-up spring mechanism 5 is disposed near a guide member 304 attached to the housing 302. The guide member 304 is disposed at a position between the thread locking portion 56 and the balance 306 in the upper thread path, and is disposed at a position where, when the balance 306 pulls the upper thread J (in the example of Figure 1, when it pulls it upward), the upper thread J can pull the thread locking unit 57 and rotate it downward (specifically, the magnet portion 64 can rotate it in the 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 disposed at 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 when viewed from the front (that is, diagonally below and to the left in the example of Figure 10)).

[0142] 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 so as to be perpendicular to the front surface of the housing 302 and parallel to an imaginary plane facing in the up-down direction. As a result, the outer surface 182a of the plate-shaped portion 182 of the thread presser disc 180 faces the left side, and the outer surface 192a of the plate-shaped portion 192 of the thread presser disc 190 faces the right side.

[0143] Furthermore, when the thread take-up spring mechanism 5 is attached to the front surface of the housing 302, the magnetic sensor attachment part 78 is located above the cylindrical part 74, and the magnetic sensor 80 faces the left side. Furthermore, when the thread locking unit 57 is not rotated, the magnet part 64 is located diagonally below the left side of the magnetic sensor 80, and the thread locking part 56 is located on the left side of the thread take-up spring attachment part 42.

[0144] To attach the thread tension control device 1 to the housing part 302, the thread take-up spring mechanism part 5 and the thread tension applying part 105 are attached to the housing part 302. To attach the thread take-up spring mechanism part 5, the insertion locking part 10 is inserted into the mounting hole 302a and then the insertion locking part 10 is rotated to lock the locking part 16 into the mounting hole 302a.

[0145] To attach the thread tension imparting unit 105 to the housing part 302, a pair of screws 220 are inserted into the insertion holes 110a and screwed into the screw holes 302b of the housing part 302, and a pair of screws 224 are inserted into the insertion holes 110c and screwed into the screw holes 302c of the housing part 302. In other words, the thread tension imparting unit 105 is attached to the housing part 302 by attaching the mounting plate part 110 to the housing part 302.

[0146] 1 and 8 to 10, the upper thread J sent from the wound thread passes through the guide hole 215 of the upper thread guide 210, reaches the thread tension applying section 105, contacts the peripheral surface of the rod-shaped member 134, passes between the thread presser disc 180 and the thread presser disc 190, contacts the peripheral surface of the cylindrical member 136 and turns around, passes between the thread presser disc 180 and the thread presser disc 190, contacts the peripheral surface of the rod-shaped member 134, reaches downward, leaves the thread tension applying section 105, and reaches the thread take-up spring mechanism 5. In other words, the upper thread J reaches the cylindrical member 136 from the rod-shaped member 134, 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 cylindrical member 136, passing between the thread presser disc 180 and the thread presser disc 190 twice.

[0147] Thereafter, the upper thread J sent to the thread take-up spring mechanism 5 comes into contact with the peripheral surface of the shaft 46, and is then locked by the thread locking portion 56, and after being locked by the thread locking portion 56, is locked by the guide member 304, and then reaches the thread take-up lever 306. The upper thread J that has passed through the thread take-up lever 306 reaches the sewing needle of the needle bar 308.

[0148] In other words, the thread take-up spring mechanism 5 is provided upstream of the balance 306 on the upper thread path, and the thread tension imparting 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 disc 180 and the thread presser disc 190.

[0149] The configuration of a sewing machine provided with the thread tension control device 1 can be diagrammatically shown in FIG. 11, in which the thread take-up lever 306, the needle bar 308 and the shuttle 310 are driven by transmitting the rotational force of a main shaft 312 via a power transmission means such as a cam mechanism or a belt mechanism, and the main shaft 312 is driven by a main shaft motor 314.

[0150] Furthermore, control circuit (control unit) 316 is a circuit that controls the operation of spindle motor 314 and electromagnets 160, 170, and controls the operation of each unit according to the data stored in memory device 318. In other words, control circuit 316 creates spindle data (see FIG. 14) according to the embroidery data read from memory device 318, and controls the operation of spindle motor 314 according to the created spindle data. Also, control circuit 316 controls the operation of electromagnets 160, 170 according to the detection result of magnetic sensor 80.

[0151] Then, depending on the spindle angle (i.e., the position in the rotational direction of the spindle), 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 positions of the thread take-up lever 306, needle bar 308, and shuttle (a position between the top dead center and the bottom dead center) are specified as shown in Fig. 15. The spindle angle is detected by an encoder provided between the spindle motor 314 and the control circuit 316.

[0152] 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 being input from the outside via the input / output device 320. Here, the stitch direction is data on the angle value with respect to a predetermined direction (for example, one direction in the horizontal direction).

[0153] The storage device 318 also stores current data (FIG. 13) which is data on the current value when the electromagnets 160, 170 are excited for each stitch.

[0154] 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 less 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.

[0155] A description will now be given of the operation of the thread tension control device 1 configured as above. In the sewing machine, the thread take-up 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.

[0156] Furthermore, in the section in which the take-up lever 306 pulls the upper thread J against the work cloth, that is, in the section in which the take-up lever 306 rises and the needle bar 308 descends, the upper thread J is tightened against the work cloth. Therefore, in the section in which the take-up lever 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 section 105.

[0157] Therefore, 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 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 sensor 80 detects that the magnetic force is off), the two electromagnets 160, 170 are excited, causing the electromagnets 160 and 170 to be attracted to each other.

[0158] The position of the magnet unit 64 when the magnetic sensor 80 detects the magnetic force as OFF is when the needle thread J is tightened while the thread take-up 306 ascends and the needle bar 308 descends, so that 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 ascending section of the thread take-up 306 (about 300 degrees to about 60 degrees) and the section where the needle bar descends (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, when the position in the section is set to a position of 10 degrees, 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 position of 10 degrees is set as the threshold value.

[0159] When the magnetic sensor 80 detects that the magnetic force is off, the electromagnets 160 and 170 are excited to attract the electromagnets 160 and 170, so that the upper thread J is sandwiched between the thread presser discs 180 and 190, and the thread take-up 306 pulls the upper thread J while the upper thread J is sandwiched, so that 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 upper thread J is sandwiched between the thread presser discs 180 and 190 becomes stronger, and therefore the tension applied to the upper thread J becomes greater.

[0160] Furthermore, when the state in which the balance 306 is pulling the upper thread is released, the thread locking unit 57 rotates back to its original position, the distance between the magnet portion 64 and the magnetic sensor 80 becomes shorter, and the value of the magnetic force detected by the magnetic sensor 80 becomes equal to or greater than a predetermined value (this is considered to be the case in which 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 the tension applied to the upper thread is released.

[0161] 16 shows a flow chart of the operation of the thread tension control device 1. 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). That is, 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. That is, 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.

[0162] 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, 170 is stopped (S5, S6). In other words, when the magnetic force turns ON, the thread take-up lever 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, 170 is stopped. To stop the excitation of the electromagnets 160, 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, 170 continues until the magnetic force turns ON.

[0163] Then, it is determined whether the target stitch is the final stitch (S7), and if it is the final stitch, the process is terminated, and if it is not the final stitch, the target stitch is updated (S8). In other words, if the target stitch was 1, the target stitch is changed to 2.

[0164] After that, the process returns to step S2, and 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, 170 are excited in accordance with the current value (S4), and the excitation continues until an on state is detected (S5, S6). The above operations are repeated to apply tension to the upper thread for each stitch.

[0165] 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 quickly attracted to each other, thereby enabling a high-speed response in applying tension.

[0166] Furthermore, 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 reversely exciting the electromagnets. Furthermore, 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 a high-speed response to cut off tension. Since the response to tension application and tension cut off can be made quickly, tension control can be performed for each stitch.

[0167] Furthermore, when no tension is being applied to the yarn, the current supply to the electromagnets 160, 170 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 electromagnets 160, 170 and to reduce the size of the electromagnets 160, 170.

[0168] Furthermore, since the yarn tension is applied by the two electromagnets 160, 170, a large yarn tension can be applied, and as a result, a wide range of yarn tension can be applied, from no yarn tension to the large yarn tension.

[0169] In addition, since the electromagnets 160, 170 are controlled in accordance with 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, they are not related to other control signals (e.g., the control signal that controls the main shaft motor 314) in the control circuit 316 in the sewing machine, and are therefore easy to install on existing sewing machines.

[0170] Furthermore, 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 to 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 to the existing sewing machine easy.

[0171] Furthermore, by providing current data, the current value when exciting the electromagnets 160, 170 can be adjusted for each stitch, thereby controlling the upper thread tension for each stitch.

[0172] 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 polarities that repel each other (i.e., reversely excited), thereby preventing the tension from the spring 200 being applied and reliably cutting off the tension on the upper thread.

[0173] The yarn tension control device 1 can be used not only for controlling the tension of the upper thread but also for other purposes.

[0174] 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 before 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) (actually, 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 highly 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, since there may be stitches in which the thread take-up lever 306 does not rise, if the detection result of the magnetic sensor 80 remains on (i.e., does not turn off) for a period of multiple stitches, it can be determined that there is a high possibility that the upper thread has broken.

[0175] When the upper thread passes through the shuttle 310 (the upper thread is locked by the shuttle 310 rotating downward), the upper thread is pulled by the shuttle 310, causing the thread locking unit 57 to rotate (in the example of FIG. 15, the upper thread J is pulled by the shuttle 310 in the range of about 245 degrees to about 290 degrees), and when the thread take-up 306 rises thereafter, the upper thread J is further pulled by the shuttle 306, causing the thread locking unit 57 to rotate further (in the example of FIG. 15, the upper thread J is pulled by the shuttle 306 in the range of about 300 degrees to about 80 degrees). However, when the upper thread J does not pass through the shuttle 310, that is, when a so-called skipped stitch occurs, the upper thread J is not pulled by the shuttle 310, and therefore the thread locking unit 57 does not rotate in that range. Note that in FIG. 15, the range of about 245 degrees to about 290 degrees is the range in which the thread take-up 306 descends.

[0176] 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, in the range of about 245 degrees to about 290 degrees), it can be determined that there is a high possibility that a skip has occurred. In other words, the yarn tension control device 1 can be used for skipped stitch detection.

[0177] In the above description, the spring 200 is provided in the storage section 152 of the electromagnet holder 140, but it may 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.

[0178] 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 surface of the storage section 132 and the electromagnet 170 contacts the flat surface 152b on the left side surface of the storage section 152 (that is, when the distance between the electromagnets 160 and 170 is the largest), if a part of the thread presser disc 180 is located within the large diameter portion 132-2 and a part of the thread presser disc 190 is located within the large diameter portion 152-2 and there is no risk of the thread presser discs 180, 190 falling, the spring 200 may be omitted.

[0179] In the above description, current data is provided to determine the current value when the electromagnets 160, 170 are excited 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 the electromagnets 160, 170 are excited may be the same for each stitch, and while the magnetic force detected by the magnetic sensor 80 is off, the electromagnets 160, 170 are excited to apply the upper thread tension.

[0180] Even if the current value for exciting 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 needle thread tension for each stitch. In other words, it is possible to quickly respond to tension application and tension release, it is possible to release thread tension 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.

[0181] In the above description, the yarn tension control device 1 is provided in the area to the right of the balance 306 in the housing part 302 when viewed from the front. However, the yarn 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.

[0182] Next, there will be described modified examples of the yarn tension control device 1. A yarn tension control device 1A as a first modified example is configured as shown in Fig. 17, and has substantially the same configuration as the yarn tension control device 1, but has a different configuration of the thread take-up spring mechanism.

[0183] In other words, 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; however, when the thread take-up spring mechanism 5' is attached to the housing 302, the position of the magnetic sensor mounting part 78 is different, 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 to the thread take-up spring attachment part 42 is different.

[0184] That is, 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 surface of the cylindrical part 74, and the magnetic sensor 80 is provided on the bottom surface 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 is rotated approximately 90 degrees to the right when viewed from the front, and the magnetic sensor 80 is located on the bottom surface side of the magnetic sensor attachment part 78.

[0185] 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 with respect to the vertical direction. That is, the thread take-up spring unit 50 of the thread take-up spring mechanism 5' has a thread take-up spring 51 made 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 wound part (not shown) fixed to the thread take-up spring mounting part 42, a protruding part 54 connected to the end of the wound part, and a thread locking part 56 connected to the tip of the protruding part 54. In addition, while the winding portion 52 of the thread take-up spring mechanism 5 winds from the base end of the protrusion 54 along the circumferential surface of the thread take-up spring mounting portion 42 toward the right toward the front side, the winding portion of the thread take-up spring mechanism 5' winds from the base end of the protrusion 54 along the circumferential surface of the thread take-up spring mounting portion 42 toward the left toward the front side.

[0186] 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.

[0187] The positional relationship between the thread take-up spring mechanism 5' and the thread tension imparting 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 located below the thread tension imparting unit 105, preferably so 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 a position on the right side of the circumferential surface of the shaft 46.

[0188] 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 in the upper thread path between the thread locking portion 56 and the balance 306, 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 it in the 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 intermediate portion 60 of the thread locking portion 56 as viewed from the front.

[0189] The method of mounting the yarn tension control device 1A to the housing 302 is the same as that of the yarn tension control device 1, and the thread take-up spring mechanism 5' and the thread tension imparting 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 yarn tension control device 1, and the method of mounting the thread tension imparting unit 105 is the same as that of the thread tension imparting unit 105 of the yarn tension control device 1.

[0190] The path of the upper thread J in the thread tension control device 1A is the same as that of the thread tension control device 1, and the upper thread that has passed through the thread tension imparting portion 105 is sent to the thread take-up spring mechanism 5', where the upper thread J comes into contact with the circumferential surface of the shaft portion 46, is locked by the thread locking portion 56, and after being locked by the thread locking portion 56, is locked by the guide member 304, and then reaches the thread take-up lever 306. The upper thread J that has passed 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 5, the upper thread J comes into contact with the upper side of the intermediate portion 60 of the thread locking portion 56, in the thread take-up spring mechanism 5', the thread locking portion 56 is provided to the right of the guide member 304, so that the upper thread J comes into contact with the lower side of the intermediate portion 60 of the thread locking portion 56.

[0191] 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 engaging portion 56 rotates the thread engaging unit 57 (rotates it to the right when viewed from the front). When the magnetic sensor 80 detects that the magnet portion 64 has moved away from 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.

[0192] The specific operation is similar to that explained with reference to the flowchart of FIG. 16 above, and therefore a detailed explanation will be omitted.

[0193] The thread tension control device 1A also has a high-speed response to tension application and tension interruption, which allows tension control for each stitch, thread tension application can be interrupted even when the electromagnets are not excited, the electromagnets 160, 170 can be made compact, a wide range of thread tension can be applied from no thread tension to a high thread tension, and installation on existing sewing machines is easy. Also, by providing current data, the current value when exciting the electromagnets 160, 170 for each stitch can be adjusted, and the upper thread tension can be controlled for each stitch.

[0194] Next, we will explain another modified example of the yarn tension control device 1. The yarn tension control device 1B as a second modified example is configured as shown in Figures 18 to 20, and has a configuration substantially similar to that of the yarn tension control device 1, but differs in that the thread take-up spring mechanism 5 and the thread tension imparting unit 105 are integrated into one unit. That is, while the thread tension control device 1 has the thread take-up spring mechanism 5 and the thread tension imparting unit 105 as separate bodies, the thread tension control device 1B has the thread take-up spring mechanism 5 and the thread tension imparting unit 105 as one body.

[0195] 18 and 19, in the yarn tension control device 1B, 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 an intermediate plate portion 111 between the mounting plate portion 20 and the mounting plate portion 110 form the mounting plate unit 100, which is configured by one 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) extending toward the thread tension imparting portion 105, and the electromagnet holder unit 119 is provided on the plate-shaped portion.

[0196] 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 portion 111, the thread take-up spring mechanism 5 has an insertion locking portion 10, an attachment plate portion 20, a guide wall portion 30, a central component 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 portion 110, an electromagnet holder 120, an electromagnet holder 140, an electromagnet 160, an electromagnet 170, thread pressure disks 180, 190, a spring 200 and an upper thread guide portion 210.

[0197] 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.

[0198] Further, the thread tension imparting unit 105 has the same configuration as the thread tension imparting 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, and therefore a detailed description thereof will be omitted.

[0199] 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, and 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 obliquely downward from the lower end of the right side of the mounting plate portion 110. The right side 111b is inclined downward and toward the left, and contacts the outer periphery of the mounting plate portion 20 so as to be tangent to the outer periphery of the mounting plate portion 20 when viewed from the front.

[0200] The method of mounting the yarn tension control device 1B to the housing part 302 is the same as that of the yarn tension control device 1, and involves inserting and locking the insertion locking part 10 into a mounting hole in the housing part 302 and locking it therein, and screwing the pair of screws 220 and the pair of screws 224 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 therein.

[0201] The path of the upper thread J in the thread tension control device 1B is the same as that in the thread tension control device 1.

[0202] 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 engaging portion 56 rotates the thread engaging unit 57 (rotates it to the left when viewed from the front). When the magnetic sensor 80 detects that the magnet portion 64 has moved away from 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.

[0203] The specific operation is similar to that explained with reference to the flowchart of FIG. 16 above, and therefore a detailed explanation will be omitted.

[0204] The thread tension control device 1B can also quickly respond to tension application and tension interruption, thereby enabling tension control for each stitch, thread tension application can be interrupted even when the electromagnets are not excited, electromagnets 160, 170 can be made compact, a wide range of thread tension can be applied from no thread tension to a high thread tension, and installation on existing sewing machines can be facilitated. In addition, by providing current data, the current value when exciting the electromagnets 160, 170 for each stitch can be adjusted, and the upper thread tension can be controlled for each stitch.

[0205] Furthermore, in the yarn tension control device 1B, the thread take-up spring mechanism 5 and the thread tension imparting unit 105 are configured as an integral unit, so that there is no need to adjust the positional relationship between the thread take-up spring mechanism 5 and the thread tension imparting unit 105 when attaching the device to the housing 302.

[0206] Next, another modified example of the yarn tension control device 1 will be described. The yarn tension control device 1C as a third modified example is configured as shown in Fig. 21 and has a configuration substantially similar to that of the yarn tension control device 1A, but differs in that the thread take-up spring mechanism 5' and the thread tension imparting unit 105 are integrated into one body. That is, while the thread tension control device 1A has the thread take-up spring mechanism 5' and the thread tension imparting unit 105 as separate bodies, the thread tension control device 1C has the thread take-up spring mechanism 5' and the thread tension imparting unit 105 integrated into one body.

[0207] That is, in the yarn 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 an intermediate plate portion 111 between the mounting plate portion 20 and the mounting plate portion 110 form the mounting plate unit 100, and the mounting plate unit 100 is composed of a single plate-shaped member.

[0208] 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.

[0209] Further, the thread tension imparting unit 105 has the same configuration as the thread tension imparting 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, and therefore a detailed description thereof will be omitted.

[0210] Moreover, the attachment plate unit 100 in the yarn tension control device 1C has the same configuration as the attachment plate unit 100 in the yarn tension control device 1B, so a detailed description thereof will be omitted.

[0211] The method of mounting the yarn tension control device 1C to the housing part 302 is the same as that of the yarn tension control device 1A, and involves inserting and locking the insertion locking part 10 into and locking the mounting hole in the housing part 302, and screwing the pair of screws 220 and the pair of screws 224 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.

[0212] The path of the upper thread J in the yarn tension control device 1C is the same as in the yarn tension control device 1A.

[0213] 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 engaging portion 56 rotates the thread engaging unit 57 (rotates it to the right when viewed from the front). When the magnetic sensor 80 detects that the magnet portion 64 has moved away from 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.

[0214] The specific operation is similar to that explained with reference to the flowchart of FIG. 16 above, and therefore a detailed explanation will be omitted.

[0215] The thread tension control device 1C can also quickly respond to tension application and tension interruption, thereby enabling tension control for each stitch, thread tension application can be interrupted even when the electromagnets are not excited, electromagnets 160, 170 can be made compact, 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. Also, by providing current data, the current value when exciting the electromagnets 160, 170 for each stitch can be adjusted, and the upper thread tension can be controlled for each stitch.

[0216] Furthermore, in the yarn tension control device 1C, the thread take-up spring mechanism 5' and the thread tension imparting unit 105 are integrally configured, so that there is no need to adjust the positional relationship between the thread take-up spring mechanism 5 and the thread tension imparting unit 105 when attaching the device to the housing 302.

[0217] In each of the modified examples of the yarn tension control devices 1A to 1C, the spring 200 may be provided in the storage portion 132 of the electromagnet holder 120, or the structure of the spring 200 may be omitted.

[0218] Furthermore, the current value for exciting the electromagnets 160, 170 may be the same for each stitch, and the yarn tension control devices 1A to 1C may be configured symmetrically and provided in an area on the left side of the thread take-up 306 when viewed from the front. [Explanation of symbols]

[0219] 1, 1A, 1B, 1C Yarn tension control device 5 Thread take-up spring mechanism 5' Thread take-up spring mechanism 9 Fixed Unit 10 Insertion locking portion 11 Screw holes 12 Cylindrical part 14 Annular section 16 Locking part 20 Mounting plate 21 Through hole 30 Guide wall 31 Through hole 32 Center 34 Annular protrusion 35 Inner slope 36 Convex part 37 Outer slope 40 Core Units 41 Central component 42 Thread take-up spring attachment 44 Shaft 46 Shaft 48 Shaft 50 Thread take-up spring unit 51 Thread take-up spring 52 Winding section 54 Protrusion 56 Thread retaining part 57 Thread retaining unit 58 Proximal end 60 Middle 62 Tip 64 Magnet section 70 Tip Unit 72 Tip 73 Through Hole 74 Cylindrical section 75 Tip wall 76 Cylindrical section 76a screw hole 77 Bis 78 Magnetic sensor mounting part 79 Cover part 80 Magnetic Sensor 100 Mounting plate unit 105 Thread tension applying section 110 Mounting plate 110a Insertion hole 110b screw hole 110c Insertion hole 110d screw hole 111 Intermediate plate 119 Electromagnet holder unit 120 Electromagnet holder 121 Holder body 122 Top part 124 Front 125 through hole 126 Back part 127 Through Hole 128 Right side part 129 Notch 129a, 129b Wall 130 Bottom part 132 Storage section 132a Inner surface 132b plane 132c Inner surface 132d plane 132K aperture 134 Rod-shaped member 136 Cylindrical member 137 Bis 138a, 138b screw holes 140 Electromagnet Holder 142 Top part 144-1 Upper front part 144-2 Lower front section 144-2a Lower front body 144-2b Projection 145 Through Hole 146 Back part 147 Recess 148 Left side part 149 Gap 150 Bottom part 152 Storage section 152a Inner surface 152b plane 152c Inner surface 152d plane 152K aperture 154 Bis 160 Electromagnet 162 Magnetic material 162a Adsorption surface 164 Coil 166 Cover part 166a Cylindrical part 166b Circular plate 170 Electromagnet 172 Magnetic material 172a Adsorption surface 174 Coil 176 Cover part 176a Cylindrical part 176b Circular plate 180 Thread presser plate 182 Plate-shaped part 184 Edge 190 Thread presser plate 192 Plate-shaped part 194 Edge 200 Spring 210 Upper thread guide 212 Vertical plate section 214 Horizontal plate part 215 Guide hole 215a Cylindrical part 215b Ring-shaped part 220, 222, 224, 226, 228 Screws 300 Sewing Machine 301 Arm section 302 Housing 302a Mounting hole 302b, 302c screw holes 304 Guide member 306 Balance 308 Needle 310 Kettle 312 Main shaft 314 Spindle motor 316 Control Circuit 318 Storage device 320 I / O device J Needle thread P, Q axis U, W Spacing

Claims

1. 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 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 3. A thread tension control device for a sewing machine as claimed in claim 1 or 2, characterized in that a 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 an opening of the target storage section.

7. 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.

8. 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.

9. 9. A thread tension applying device for a sewing machine as described in claim 7 or 8, characterized in that a 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 an opening side of the target storage section.

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