JP2008029591A - Sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sewing machine capable of adjustably imparting prescribed tension to a needle thread. <P>SOLUTION: The sewing machine 1 comprises: a delivery device 30 for delivering the needle thread T from a thread piece 13; first and second solenoids 40 and 50 for clamping the needle thread T on the upstream and downstream sides from the delivery device 30 inside a needle thread route and individually switching the regulation and opening of the movement of the needle thread T; an encoder 60 for detecting the delivery amount of the needle thread T; a base tension 70 for imparting the tension to the needle thread T advancing to the first solenoid 40; a thread tension guide 80 for adjustably imparting the prescribed tension to the needle thread T; a thread take-up lever mechanism 90 for pulling out the needle thread on the downstream side from the second solenoid; and a control part 100 for controlling the drive of respective configurations. Then, by imparting the tension from the thread tension guide 80 in the state of releasing both of the first and second solenoids 40 and 50, the needle thread T of an appropriate length is delivered even in the sewing of free embroidery or the like and beautiful stitches are obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sewing machine including an automatic thread tension device having a lever for feeding a necessary amount of upper thread for each needle.

Conventionally, in a sewing machine equipped with an automatic thread tension device that feeds a necessary amount of upper thread for each stitch, it is arranged on the upper thread feeding path (hereinafter referred to as upper thread path) and the movement of the upper thread is individually controlled. A first and second solenoid that regulates or releases the lever, a lever that is disposed between the first and second solenoids in the upper thread path and applies a pulling force for pulling out the upper thread, that is, a feeding balance, And an encoder for measuring the length (yarn amount) of the yarn actually drawn by the feeding balance.
Then, the appropriate upper thread feed amount for each stitch is calculated from the fabric thickness information obtained from the fabric thickness detection potentiometer and the pattern information in which sewing data such as the needle swing amount and fabric feed amount is set. When the amount of feeding detected by the encoder, that is, the amount of yarn actually fed by the feeding balance, coincides with the calculated value, the solenoids are operated to regulate the amount of upper yarn (for example, patent Reference 1).
JP-A-57-93091

However, in the above-described conventional sewing machine, an appropriate amount of needle thread is fed out for each stitch in sewing with pattern information set. However, for example, a user may perform sewing during sewing such as free embroidery or quilt sewing. When the cloth is manually moved and sewing is performed without using preset pattern information, it is difficult to appropriately control the upper thread amount. That is, if the upper thread feed amount is insufficient, troubles such as broken needles may occur, and if the upper thread fed out is excessive, the seam is not tightened and a beautiful seam cannot be obtained. there were.
As a method for solving the above problem, it is conceivable to perform sewing by releasing both the first and second solenoids and allowing the upper thread to be freely fed out. However, the upper thread path is provided with a base tension in addition to the above-mentioned components, but this base tension is set at an extremely light pressure for the purpose of untwisting the upper thread fed from the yarn spool. In general, it is not possible to apply an appropriate tension to the upper thread. As described above, in free embroidery and quilt sewing, it is difficult to feed an appropriate amount of upper thread for each stitch, and there is a problem that the seam is not tightened and a beautiful seam cannot always be obtained.

  An object of the present invention is to optimize the tension applied to the upper thread.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a feeding unit arranged in the upper yarn path for feeding the yarn from the yarn supply source side and an upper side in the upper yarn path upstream of the feeding unit. A first solenoid that switches between restriction and release of movement of the upper thread by gripping the thread, and restriction of movement of the upper thread by gripping the upper thread downstream of the feeding means in the upper thread path A second solenoid that switches between releasing and releasing, a feed amount detecting means for detecting the feed amount of the upper thread, a balance mechanism for pulling the upper thread downstream from the second solenoid, and the feed means in the upper thread path A tension applying means disposed downstream of the upper thread so as to adjustably apply a predetermined tension to the upper thread and release the tension; In this case, a normal sewing mode for performing control for switching between restriction and release of the first and second solenoids so that a predetermined length of payout is performed for each stitch in accordance with the detection of the feed amount detecting means, A control means for controlling the drive of the actuator so as to release the tension applying means in the normal sewing mode, switching between a release mode for performing control for releasing both the first and second solenoids according to an input instruction; It is a sewing machine characterized by comprising.

  According to the first aspect of the present invention, the normal sewing mode and the release mode are switched by the control means in accordance with the input instruction. Then, in the release mode, control for releasing both the first and second solenoids is performed by the control means. At that time, a predetermined tension can be applied to the upper thread in an adjustable manner by a tension applying means provided in the sewing machine. Thus, for example, even in sewing where it is difficult to control the amount of the upper thread, such as free embroidery or quilt stitching, an appropriate tension can be applied to the upper thread, so that the upper thread of an appropriate length can be fed out. . As a result, it is possible to obtain a beautiful seam without causing a fastening failure due to needle breakage or a thread remainder.

  In addition, since the tension applying unit is driven by the actuator, the tension applying unit can be controlled by the control unit. As a result, in the normal sewing mode, it is possible to feed the upper thread of an appropriate length for each stitch by switching between the restriction and release of the first and second solenoids without considering the influence of tension by the tension applying means. it can. Further, in the release mode, the upper thread of an appropriate length can be fed out by the predetermined tension applied by the tension applying means without restricting the movement of the upper thread by the first and second solenoids. That is, in the release mode, while the predetermined tension is applied to the upper thread by the tension applying means, in the normal sewing mode, the control means does not apply the tension by the tension applying means to the upper thread according to the detection of the feed amount detecting means. By performing control to switch between regulation and release of the first solenoid and the second solenoid, the upper thread of a predetermined length can be fed out.

  Further, since the tension applying means is disposed downstream of the feeding means in the upper thread path, the tension applying means is disposed upstream of the feeding means when tension is applied to the upper thread by the tension applying means. Appropriate tension can be applied to the upper thread supplied to the needle without being affected by each mechanism.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.
In the present embodiment, as an example of the sewing machine, an automatic thread tension device will be described, and a home sewing machine that performs free embroidery and quilt sewing as well as embroidery sewing using the automatic thread tension device will be described. Here, the direction perpendicular to the needle plate surface (not shown) is the Z-axis direction (up and down direction), the longitudinal direction of the sewing machine arm portion 11 perpendicular to this is the Y-axis direction (front and rear direction), and the Z-axis direction and the Y-axis direction The direction orthogonal to both of these is defined as the X-axis direction (left-right direction).

(Overall configuration of the embodiment)
FIG. 1 is a perspective view showing a main configuration of a household sewing machine 1 (hereinafter simply referred to as a sewing machine 1) according to the present embodiment.
As shown in FIG. 1, the sewing machine 1 is disposed near the needle drop position by a cloth presser 14 that prevents the sewing product from being lifted in the vicinity of the needle drop position, and the cloth feed means (not shown). The potentiometer 20 as a cloth thickness detecting means for detecting the thickness (cloth thickness) of the cloth to be sewn conveyed to the sewing thread, and the upper thread T from the side of the thread sesame 13 which is disposed in the upper thread path and is a thread supply source A feeding device 30 as feeding means for feeding, and a first solenoid 40 that switches between restriction and release of movement of the upper yarn T by gripping the upper yarn T upstream of the feeding device 30 in the upper yarn path; A second solenoid 50 for switching the restriction and release of the movement of the upper thread T by gripping the upper thread T downstream of the feeding device 30 in the upper thread path; An encoder 60 serving as a feed amount detecting means for detecting the tension, a base tension 70 for applying tension to the upper thread T entering the first solenoid 40, and an upper thread disposed downstream of the feeding device 30 in the upper thread path. A thread tension device 80 as tension applying means for applying a predetermined tension to T in an adjustable manner, a balance mechanism 90 for pulling the upper thread downstream from the second solenoid, and driving of each of the above configurations based on predetermined sewing data The control part 100 which controls this is provided.
The sewing machine 1 is connected to a sewing machine motor 5 serving as a driving source for the sewing machine operation, and is rotatably provided to drive the sewing needle 16 up and down by converting the rotational driving force of the upper shaft into vertical movement. The sewing machine has general functions for sewing, such as a needle driving mechanism that performs sewing, a cloth feeding mechanism that conveys cloth to be sewn, and a lower shaft that transmits driving force to the cloth feeding mechanism. Since it is the same as a well-known structure, illustration and description are abbreviate | omitted in this embodiment.

Here, “near the needle drop position” refers to a region in the vicinity of the needle drop position where the sewing needle 16 performs sewing by moving up and down, and upstream of the needle drop position in the cloth feeding direction.
The “upper thread path” refers to the base tension 70, the first solenoid 40, the encoder 60, the feeding device 30, the second solenoid 50, the thread tension device 80, the thread take-up from the thread sesame 13 that is the supply source of the upper thread T. The path from the spring 79 and the balance mechanism 90 to the sewing needle 16 through the described order. In addition, thread hooks (not shown) are provided at various points along the path.
Further, the “predetermined sewing data” is used to control each of the driving units in order to perform sewing operations such as needle movement and cloth feed for forming a stitch, an embroidery pattern, and the like, feeding of the upper thread T, cutting, and the like. Data including various parameters is assumed to be preset and stored in the storage unit of the control unit 100.
Hereafter, each said structure is demonstrated in detail.

  The cloth presser 14 is disposed on the distal end side of the sewing machine arm portion 11, and prevents the cloth conveyed from the upstream side in the cloth feeding direction by a cloth feeding mechanism (not shown) from above to the upper surface of the needle plate. It is something to hold down. The cloth presser 14 includes a cloth presser bar 14a that extends in the vertical direction and is provided so as to freely move up and down, and a presser foot 14b supported on the lower end of the cloth presser bar. Further, one end of a link 17 is rotatably connected to the cloth presser 14, and a substantially center of the link 17 is fixed to a detection shaft of a potentiometer 20 fixedly supported by a sewing machine frame. Further, a presser spring 18 is connected to the other end of the link 17, and the other end of the link 17 is always urged upward by the presser spring 18, so that the cloth presser connected to one end side of the link 17. 14 is always urged downward.

  The potentiometer 20 is fixedly supported by the sewing machine frame and is connected to substantially the center of the link 17 connected to the cloth presser 14. For this reason, when the cloth presser 14 moves up and down according to the thickness of the cloth conveyed near the needle drop position by a conveying means (not shown), the detection shaft of the potentiometer 20 is rotated via the link 17, The angle in the direction of rotation changes. By detecting the angle of the detection shaft, the thickness of the cloth in the vicinity of the needle drop position can be detected at any time. The cloth thickness detected by the potentiometer 20 is converted into an electrical signal and transmitted to the control unit 100 described later.

  The base tension 70 is mounted on the sewing machine arm portion 11 and is disposed on the upstream side of the first solenoid 40 described later in the upper thread path. The base tension 70 is a pair of plate-shaped or dish-shaped members that are opposed to each other via an elastic member, and is drawn out from the thread sesame 13 that is a supply source of the upper thread T and enters the first solenoid 40. By elastically holding the upper thread T, the upper thread T entering the first solenoid 40 has a function of untwisting. The base tension 70 has a function of constantly applying a constant tension to the upper thread T by a spring pressure to prevent the upper thread T from sagging from the base tension 70 to the sewing needle 16.

The first solenoid 40 is disposed on the downstream side of the base tension 70 in the upper thread path and upstream of the feeding device 30 described later. The first solenoid 40 is electrically connected to a control unit 100, which will be described later, and can be switched ON / OFF freely according to a control signal from the control unit 100. The first solenoid 40 is configured to release and hold the upper thread T in the OFF state and to hold the upper thread T in the ON state to restrict its movement.
The first solenoid 40 clamps the upper thread T from the thread sesame 13 side while holding the upper thread T when the balance mechanism 90 performs the fastening operation of the upper thread T when the second solenoid 50 described later is OFF. This is for regulating the feeding.

  The encoder 60 is disposed at a position close to the first solenoid 40 in the upper thread path. Then, after the upper thread T that has passed through the first solenoid 40 passes through the rotor that is the detection unit of the encoder 60, it is supplied to the downstream side again through the first solenoid 40. The encoder 60 is for measuring the length of the upper thread T that is actually pulled out from the thread sesame 13 by the feeding device 30 to be described later and passes through the first solenoid 40, and is measured by the encoder 60. The feeding amount of the yarn T is converted into an electric signal and transmitted to the control unit 100 described later.

  The second solenoid 50 is disposed downstream of a feeding device 30 (to be described later) in the upper thread path and is electrically connected to the control unit 100, and the control from the control unit 100 is the same as the first solenoid 40 described above. Control that can be switched ON / OFF freely according to the signal is possible. The second solenoid 50 is configured to release and hold the upper thread T in the OFF state and to hold the upper thread T in the ON state to restrict its movement.

  The feeding device 30 is provided at the tip of the sewing machine arm portion 11, that is, on the surface portion side, and has a feeding regulating plate 31 having a plane along which the upper yarn T is aligned, and the upper yarn T is pulled to a position deviated from the plane of the feeding regulating plate 31. A feeding balance 32 is provided. Further, a face plate 38 is provided on the front surface of the feed restricting plate 31 in parallel with the feed restricting plate 31 (see FIG. 1).

As shown in FIG. 1, the feed restricting plate 31 is a plate-like member disposed along the plane of the surface portion on the surface portion side of the tip of the sewing machine arm portion 11. A slit 31 a that is long along the feed restriction plate 31 is formed. The upper thread T passes through the front side of the feed restricting plate 31 (in the direction of arrow B in FIG. 1) along the front surface of the feed restricting plate 31 substantially in the X-axis direction (left and right direction).
The feeding restricting plate 31 is fixed to the sewing machine arm 11 (sewing frame), and a pulling force for feeding the upper thread T to a part of the upper thread T on the upper thread path by a feeding balance 32 described later is provided. When applied, the upper thread T on the upper thread path is regulated on the left and right sides across the forward / backward path of the feeding balance 32, that is, on the upstream side and the downstream side of the forward / backward path of the feeding scale 32 in the upper thread path. A function of maintaining the upper thread path along the end face on the front side of the plate 31 is provided.

  As shown in FIG. 1, the face plate 38 is attached to the front surface of the feed restricting plate 31, and is disposed on the front side of the feed restricting plate 31 with a gap between the face restricting plate 31 and the face restricting plate 31. In the face plate 38, a slit 38 a is formed at a position facing the slit 31 a of the above-described feed restricting plate 31, similarly to the above-described feed restricting plate 31. The face plate 38 regulates the movement in the front-rear direction and the up-down direction so that the upper thread T passing along the front surface of the feeding restriction plate 31 is disposed in the yarn hooking portion 32a of the feeding balance 32, and the slit 38 38a has a function of preventing the operator from contacting the feeding balance 32 that is driven back and forth while allowing the feeding balance 32 described later to move back and forth.

  As shown in FIG. 1, the feeding balance 32 has a thread hooking portion 32 a that has an L-shaped tip and is bent upward, and the yarn hooking portion 32 a is a slit of the feeding restriction plate 31 described above. Advancing and retreating movement is provided on the front side of the feed restricting plate 31 through 31a. The feeding balance 32 can be reciprocated back and forth along the Y-axis direction (arrow A direction and B direction in FIG. 1) in accordance with the rotation of the upper shaft interlocked with the sewing machine motor 5. That is, the feeding balance 32 is reciprocated in a direction substantially perpendicular to the upper thread path (Y-axis direction) for each needle in synchronization with the rotation of the upper shaft, whereby the yarn hooking portion 32a of the feeding balance 32 is performed. An upper thread having a length corresponding to the distance between the rear end of the thread and the front surface of the feed restricting plate 31 is fed from the thread sesame 13.

  The balance mechanism 90 is disposed on the downstream side of the second solenoid 50 in the upper thread path, and the upper thread T is moved upward when the sewing needle 16 penetrating to the lower side of the cloth is lifted out of the cloth, that is, immediately after sewing. A conventionally well-known configuration is employed in which the seam is pulled up and fastened.

Here, based on FIG.1 and FIG.2, the thread tension device 80 in this embodiment is demonstrated.
As shown in FIG. 1, the thread tension device 80 is disposed between the feeding device 30 and the balance mechanism 90 described above in the upper thread path, that is, downstream from the feeding device 30 and upstream from the balance mechanism 90. Has been placed.
As shown in FIG. 2, the thread tension device 80 includes a pair of thread tension plates 81 and 81 for holding the upper thread T, a shaft 82 that holds the thread tension plates 81 and 81 coaxially, A thread tension spring 83 for urging the thread tension tray 81 toward the other thread tension tray 81, and rotating about the shaft 82 to move forward and backward in the thrust direction of the shaft 82. A dial 84 for adjusting the clamping force of the upper thread T by the thread tension plates 81, 81, that is, the thread tension, and a thread tension pulse motor 85 that is a drive source for rotating the dial 84, that is, an actuator, are provided. .

The thread tension pulse motor 85 is electrically connected to a control unit 100, which will be described later, and rotates the dial 84 by rotating a predetermined amount based on a signal from the control unit 100 to be applied to the upper thread T. Adjust the pressure. That is, the thread tension device 80 can adjust the tension applied to the upper thread T according to the driving of the thread tension pulse motor 85.
Then, the thread tension pulse motor 85 in the present embodiment can be brought into a released state in which no tension is applied to the upper thread T by rotating the dial 84. That is, the thread tension pulse motor 85 functions as an actuator of the present invention that releases the thread tension device 80 as the tension applying means.
The relationship between the tension applied to the upper thread T by the thread tension pulse motor 85 rotating the dial 84 and moving in the thrust direction and the amount of rotation of the thread tension pulse motor 85 are measured in advance and the corresponding relationship. Is stored in the ROM 102 which is a storage means of the control unit 100.

(Sewing machine control system)
Next, the configuration of the control unit 100 will be described with reference to FIG.
As shown in FIG. 3, the control unit 100 is connected to drive sources such as the sewing machine motor 5 and the thread tension pulse motor 85, detection means such as the encoder 60, the sewing machine starting pedal 15, and the operation panel 110. FIG. 3 shows only the configuration necessary for the present embodiment, and the control unit 100 includes other drive sources, sensors, and the like.
The control unit 100 includes an MPU (Micro Processor Unit) 101 which is a microcomputer, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and an EEPROM (Electrically Erasable and Programmable ROM) 104. Yes.
The ROM 102 stores a control program for the sewing machine 1. The RAM 103 is a memory that provides a work area to the MPU 101. Various data related to sewing are backed up in the EEPROM 104. Then, the MPU 101 performs processing according to the control program stored in the ROM 102.

The control unit 100 stores a table indicating the relationship between the rotation angle of the upper shaft and the vertical position of the balance 90. The control unit 100 detects the rotation angle of the upper shaft from an encoder 5 a provided in the sewing machine motor 5. Further, the control unit 100 holds the upper thread T by turning on the first solenoid 40 from the start to the end of lifting of the balance 90 based on the detected rotation angle of the upper shaft, and holds the upper thread T by turning off the second solenoid 50. Control to release.
Further, the control unit 100 has a cloth thickness-upper thread feed amount table, and determines the feed amount of the upper thread T by detecting the fabric thickness between the end of lifting of the balance 90 and the start thereof.

Further, the control unit 100 according to the present embodiment performs the first solenoid 40 and the second solenoid so that a predetermined length of feeding is performed for each stitch according to the detection of the encoder 60 when the upper thread T is fed by the feeding device 30. Functions as a control means for performing control by switching between a normal sewing mode for performing control for switching between restriction and release of the solenoid 50 and a release mode for performing control for releasing both the first solenoid 40 and the second solenoid 50 according to an input instruction. To do. Note that switching between the normal sewing mode and the release mode is performed by the user pressing a mode switching button 111 provided on the operation panel 110 shown in FIG.
Further, the control unit 100 controls the driving of the thread tension solenoid 85 so as to release the thread tension device 80 in the normal sewing mode. That is, when the mode switch button 111 is pressed by the user to set the normal sewing mode, the control unit 100 drives the thread tension pulse motor 85 to release the thread tension device 80, and from the thread tension device 80, Control is performed to drive the feeding device 30 (the sewing machine motor 5), the first solenoid 40, and the second solenoid 50 at a predetermined timing in a state where no tension is applied to the upper thread T.

(Description of sewing machine operation)
Next, the operation of the sewing machine 1 according to the present embodiment will be described in detail.
First, in the normal sewing mode, after passing the top dead center of the balance 90 (after completion of the lifting), the thickness of the cloth conveyed from the upstream side in the cloth feeding direction and approaching the needle drop position with the sewing operation of the sewing machine 1 It is detected by the potentiometer 20.
Next, the cloth thickness detected by the potentiometer 20 is read by the control unit 100, and the cloth thickness is determined based on the cloth thickness and the correspondence table of the cloth thickness-feeding amount stored in the ROM 102 serving as the storage means. The optimum upper thread take-up length is calculated when the needle drop is performed in the vicinity of the detected position. Then, the control unit 100 performs control to execute a feeding operation for feeding the upper thread T having an optimum length based on the calculated value.
Here, the feeding operation of the upper thread T will be described. When the upper thread T is fed out, first, the control unit 100 performs control to turn off the first solenoid 40 and turn on the second solenoid 50. Thereby, the clamping part of the 1st solenoid 40 is open | released, and the upper thread | yarn T currently spanned upstream from the drawing | feeding-out apparatus 30 in the upper thread | yarn path | route will be in a movable state. Further, the upper thread T that is stretched downstream from the feeding device 30 is pinched by the pinching portion of the second solenoid 50 and its movement is restricted.

Next, the control unit 100 reads the calculated value based on the cloth thickness stored in the ROM 102 serving as storage means and predetermined sewing data.
When the feeding balance 32 is moved to the rear side, when the yarn hooking portion 32a of the feeding balance 32 passes through the slit 31a of the feeding regulating plate 31, the end of the yarn hooking portion 32a on the rear side with respect to the upper thread T. Thus, a pulling force toward the rear side, that is, in the direction of arrow A in FIG.

Here, the upper thread T captured by the yarn hooking portion 32a of the feeding balance 32 is pulled by the yarn hooking portion 32a and moved to the rear side. On the other hand, the upper thread T positioned on both the left and right sides of the feeding balance 32 is restricted from moving rearward by the front end face of the feeding regulating plate 31. That is, the feeding balance 32 is moved rearward (in the direction of arrow A in FIG. 1) by a length approximately half of the movement distance of the optimum feeding length of the upper thread T.
Further, as described above, since the second solenoid 50 is in an ON state while the feeding operation is being performed, the movement of the upper thread T on the downstream side of the upper thread path from the feeding balance 32 is restricted. ing. Therefore, the upper thread T having the optimum length is fed from the upstream side of the upper thread path with respect to the feeding balance 32, that is, from the thread sesame 13 serving as a supply source of the upper thread T.

Next, when the feeding balance 32 is moved to the rearmost position, the control unit performs control to turn on the first solenoid 40 and turn off the second solenoid 50. Thereby, the upper thread T on the upstream side of the feeding device 30 is restricted from moving along the upper yarn path, and the upper thread T on the downstream side of the feeding device 30 is in a movable state.
In this state, the feeding balance 32 is moved to the front side. Simultaneously with the movement of the feeding balance 32 to the front side, the operation of fastening the upper thread T is executed by the balance mechanism 90 on the downstream side of the upper thread path. That is, as the sewing needle 16 is raised, the balance 90 pulls the upper thread T and performs an operation of fastening the seam.
In conjunction with this fastening operation, a pulling force toward the downstream of the upper thread path is applied to the upper thread T on the downstream side of the first solenoid 40. For this reason, the upper thread T of the optimum length fed by the feeding balance 32 passes through the second solenoid 50 and is fed downstream of the upper thread path and supplied to the sewing needle 16.
Then, while the sewing operation is continued, the control unit 100 repeatedly executes the control of feeding the upper thread T of the optimum length for each stitch according to the fabric thickness detected by the potentiometer 20.

Next, when the user presses the mode switching button 111 on the operation panel 110 to set the release mode, the control unit 100 releases both the first solenoid 40 and the second solenoid 50 and the thread tension pulse motor 85. And the tension control device 80 controls the tension of the upper thread T. The tension applied to the upper thread T by the thread tension device 80 can be adjusted as desired by driving the thread tension pulse motor 85. Thereby, an appropriate predetermined tension is applied to the upper thread T.
The yarn hooking operation when attaching the upper thread T to the sewing machine 1 is performed in such a manner that the upper thread T fed from the thread sesame 13 is arranged in order from the upstream side of the upper thread path, the base tension 70, the first solenoid 40, the encoder 60, This can be easily performed by attaching the feeding device 30, the second solenoid 50, the balance 90, and the sewing needle 16 in this order.

(Effect of embodiment)
As described above, according to the sewing machine 1 according to the present embodiment, an appropriate tension can be applied to the upper thread T even in sewing where it is difficult to control the amount of the upper thread, such as free embroidery or quilt sewing. It is possible to obtain a beautiful seam without causing broken needles or poor fastening due to the thread remainder.
Further, the control unit 100 controls the driving of the thread tension pulse motor 85 so as to release the thread tension device 80 in the normal sewing mode, so that the tension is not applied to the upper thread T by the thread tension device 80. Since the state can be switched, an appropriate tension can be applied to the upper thread T according to the sewing mode. That is, in the normal sewing mode, an upper thread having an appropriate length for each stitch can be obtained by switching between restriction and release of the first solenoid 40 and the second solenoid 50 without considering the influence of the tension by the thread tension device 80. T can be paid out. Further, in the release mode, the upper thread T is fed out by a predetermined tension applied by the thread tension device 80 without restricting the movement of the upper thread T by the first solenoid 40 and the second solenoid 50. be able to.
In addition, since the thread tension device 80 is arranged on the downstream side of the feeding balance 32 in the upper thread path, when the tension is applied to the upper thread T by the thread tension device 80, Also, an appropriate tension can be applied to the upper thread T supplied to the sewing needle 16 without being affected by each mechanism arranged on the upstream side.

(Other)
In the present embodiment, the thread tension device 80 disposed between the second solenoid 50 and the balance mechanism 90 is driven by an actuator, that is, a thread tension pulse motor 85, and can be controlled by the control unit 100. However, for example, the tension applied to the upper thread T from the thread tension device 80 may be adjusted by manually rotating the dial 84 without providing the thread tension pulse motor 85.
In this embodiment, the thread tension device 80 is provided separately from the base tension 70. For example, as shown in FIGS. 4 and 5, a spring 173 is attached to the base tension 170 disposed in the upper thread path. And a dial 174, and the pressure applied to the upper thread T from the base tension 170, that is, the upper thread tension, can be adjusted by rotating the dial 174 in the thrust direction along the shaft 172. . In this case, for example, a pulse motor may be provided as an actuator for driving the dial 174.

It is a schematic perspective view which shows the principal part structure of the sewing machine which concerns on this invention. It is a side view which shows the thread tension device in this embodiment. It is a control block diagram which shows the structure of the control part in this embodiment. It is a schematic perspective view which shows the other example to which this invention is applied. It is a side view which shows the base tension in the other example to which this invention is applied.

Explanation of symbols

1 sewing machine (household sewing machine)
5 Sewing Motor 11 Sewing Machine Arm 13 Thread Sesame (Thread Supply Source)
14 Cloth presser 15 Sewing machine starting pedal 16 Sewing needle 17 Link 18 Presser spring 20 Potentiometer (cloth thickness detecting means)
30 Feeding device (feeding means)
31 Feeding restricting plate 31a Slit 32 Feeding balance 32a Threading portion 38 Face plate 40 First solenoid 50 Second solenoid 60 Encoder (Feeding amount detecting means)
70 Base tension 79 Thread take-up spring 80 Thread tension device (tension applying means)
85 Thread tension pulse motor (actuator)
90 Balance (balance mechanism)
100 Control unit (control means)
T Upper thread

Claims (1)

Unwinding means arranged in the upper thread path to unwind the thread from the thread supply source side;
A first solenoid that switches between restriction and release of movement of the upper thread by gripping the upper thread upstream of the feeding means in the upper thread path;
A second solenoid that switches between restriction and release of movement of the upper thread by gripping the upper thread downstream of the feeding means in the upper thread path;
A feed amount detecting means for detecting a feed amount of the upper thread;
A balance mechanism for pulling the upper thread downstream from the second solenoid;
Tension applying means provided with an actuator that is disposed downstream of the feeding means in the upper thread path and applies a predetermined tension to the upper thread in an adjustable manner and releases the tension;
Control is performed to switch between restriction and release of the first and second solenoids so that a predetermined length of feed is performed for each stitch according to the detection of the feed amount detection means when the yarn is fed by the feed means. Switching between a sewing mode and a release mode in which control is performed to release both the first and second solenoids is performed according to an input instruction, and in the normal sewing mode, driving of the actuator is controlled so as to release the tension applying means. And a control means.

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