JP2792203B2 - Sewing machine with automatic thread trimming mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sewing machine with an automatic thread trimming mechanism, and in particular, a needle thread cut at the end of sewing even when sewing is interrupted at a needle lower position immediately after the start of sewing. Of the upper thread end holding mechanism of the upper thread end holding mechanism.

(Prior art)

Conventionally, as described in, for example, JP-A-56-139793, at the end of sewing, the movable blade is engaged with the fixed blade via the drive of the lower shaft between the needle plate and the shuttle to drive the upper thread and the lower thread. A sewing machine provided with a thread trimming mechanism for automatically cutting at a predetermined timing is already known.

If the thread amount from the eye of the sewing needle to the thread end of the upper thread is short in this sewing machine with a thread trimming mechanism, the thread end of the upper thread will fall out of the eye at the first needle at the start of sewing. To prevent this, the yarn is cut while leaving a large amount of yarn from the eye hole to the yarn end.

However, when sewing with this sewing machine with a thread trimming mechanism,
Although the upper thread can be prevented from coming off from the eye, the amount of thread from the eye to the end of the thread is long, so the upper thread remains long on the back side of the fabric and is entangled with the lower thread from the second stitch, as shown in FIG. As shown, there is a problem that the upper thread Ns and the lower thread Bs are entangled in a bird's nest on the back side of the fabric W, and the quality of the sewn product is extremely reduced.

Japanese Utility Model Laid-Open Publication No. 61-157487 discloses that the first thread at the start of sewing prevents the thread end of the upper thread from coming out of the eye hole, and the upper thread and the lower thread are nested on the back side of the fabric. In order to prevent entanglement in the shape, after the sewing is completed, the end of the upper thread cut by the thread cutting mechanism is captured by the thread capturing member above the needle plate, and the upper thread end is captured by the thread holding member and the thread capturing member. A sewing machine provided with a thread holding device for holding the sewing needle at a position far away from the sewing needle in cooperation with the sewing machine has been proposed.

However, in the sewing machine equipped with this thread holding device, the upper thread and the lower thread do not become entangled in a bird's nest on the back side of the work cloth at the start of sewing, but as shown in FIG. Since the length of the yarn Ns to the yarn end is long and the upper yarn end is held at a position far away from the eye hole, the long upper yarn Ns remains on the front side of the fabric W, and the upper yarn end There is a problem that a thread picking operation for cutting the thread is required, and that the uncut portion of the upper thread Ns remains on the cloth surface even after the thread picking operation.

Accordingly, the applicant of the present application has filed Japanese Patent Application No. 1-285660,
At the end of sewing, the upper thread end portion of the upper thread cut short by the thread cutting mechanism is held by the thread holding member in cooperation with the holding force applying member at the thread holding position near the side of the sewing needle located at the uppermost position. The upper thread end is held for a predetermined time from the start of sewing until the interlacing of the upper thread and the lower thread of the first stitch is formed, and after the lapse of time, the upper thread holding member is moved to the standby position and the upper thread is moved. We have proposed a sewing machine with a thread trimming mechanism that has an upper thread end holding mechanism that releases the end, and the upper thread end remains short without being entangled with the lower thread on the back side of the fabric.

[Problems to be solved by the invention]

In the sewing machine with a thread cutting mechanism proposed by the applicant of the present invention, in order to synchronize the timing of moving the thread holding member to the thread catching position, the thread holding position, or the standby position with the rotation phase of the upper shaft driven by the sewing machine motor. It is conceivable to provide a large number of slits on the peripheral edge of a disk-shaped disk attached to the upper shaft, and to use a pulse signal output from a sensor through these slits.

Therefore, the thread release timing for moving the thread holding member to the standby position from the start of sewing can be set by the number of pulses immediately after the start of sewing, and this number of thread release pulses can be set from the operation panel.

By the way, this type of sewing machine usually has a needle down stop function for stopping the drive of the sewing machine motor at the needle down position immediately after sewing so that the needle drop position at the start of sewing can be confirmed.

Here, even if a needle down stop command is input and the operation of the brake is started, the upper shaft cannot be stopped immediately, and the upper shaft rotates and stops at a small angle while slipping with the brake shoe. However, during this time, a pulse signal is output and the count proceeds.

Therefore, when the number of pulses for setting the thread release timing is set to a small value, the thread holding member is switched to the standby position and the upper thread end is released almost simultaneously with the interruption of the sewing operation at the needle down position. However, when sewing is resumed, there is a problem that the upper thread end comes off the eye of the sewing needle.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sewing machine with an automatic thread trimming mechanism capable of restarting sewing without removing a thread from a sewing needle even when a sewing operation is interrupted at a needle lower position immediately after the start of sewing.

[Means for solving the problem]

A sewing machine with an automatic thread trimming mechanism according to the present invention, a sewing needle driven via an upper shaft by a sewing machine motor, a balance that is driven up and down in synchronization with the sewing needle, a shuttle that entangles an upper thread and a lower thread,
A thread trimming mechanism that automatically cuts the upper thread and lower thread between the needle plate and the shuttle in response to the thread trimming command, and a thread that applies resistance to the upper thread between the thread supply source and the balance A tension mechanism, a tension release mechanism for releasing the resistance applied to the upper thread by the thread tension mechanism, a thread catching position near the lowermost position of the sewing needle located at the uppermost position, and a lateral vicinity of the sewing needle located at the uppermost position. The yarn holding member is located above the yarn holding position, is movable above the yarn holding position, and is movable between a standby position where the upper yarn end is released, and cooperates with the yarn holding member at the yarn holding position. An upper thread end holding mechanism having a holding force applying member for holding the yarn end, and an upper thread end holding mechanism operatively connected to the thread holding member for selectively switching the thread holding member to three positions. In a sewing machine with an automatic thread trimmer equipped with a thread holding driving means, the A pulse signal generating means for outputting a signal, and after the thread cutting operation of the thread cutting mechanism is completed, the thread holding member is moved from the standby position to the thread holding position via the thread catching position, and a pulse signal generating means is provided after the start of the sewing machine motor. Holding control means for controlling the thread holding driving means so as to move the thread holding member to the standby position when a predetermined number of pulse signals output from the sewing machine are counted, and a needle down stop for the sewing machine motor at the start of the start of the sewing machine motor. Command control means for instructing the thread holding control means to stop counting the pulse signal when the command is input and to position the thread holding member at the thread holding position for a predetermined time from the restart of the sewing machine motor. It is provided.

[Action]

In the sewing machine with the automatic thread cutting mechanism according to the present invention,
The thread holding control means is configured to move the thread holding member from the standby position to the thread holding position via the thread catching position after the end of the thread cutting operation by the thread cutting mechanism with the tension release mechanism activated at the end of the sewing operation. Since the yarn holding driving means operatively connected to the yarn holding member of the upper yarn end holding mechanism is controlled, the yarn holding member holds the upper yarn end in cooperation with the holding force applying member at the yarn holding position. I do. Further, when the sewing is started by the start of the sewing machine motor, the thread holding control means, in a state where the tension release mechanism is operated, the thread holding member is activated when the pulse signal output from the pulse signal generating means is counted by a predetermined number. Since the yarn holding drive unit is controlled to move to the standby position where the upper yarn end is located above the yarn holding position and the upper yarn end is released, the upper yarn end is released.

On the other hand, when the needle stop command to the sewing machine motor is input at the start of the start of the sewing machine motor, the command control means stops the counting of the pulse signal and moves the thread holding member to the thread holding position for a predetermined time from the restart of the start of the sewing machine motor. To the yarn holding controller.

〔The invention's effect〕

According to the sewing machine with the automatic thread cutting mechanism according to the present invention, the needle down stop command to the sewing machine motor is input at the start of the start of the sewing machine motor by providing the pulse signal generating unit, the thread holding control unit, and the command control unit. Sometimes, the counting of the pulse signal is stopped, and the thread holding member is held at the thread holding position while holding the upper thread end for a predetermined time from the restart of the sewing machine motor. Even when the predetermined number of pulses to be moved to the position is set to a small value, the upper thread end is securely held by the thread holding member when the needle lowering stops, and the upper thread is pulled out from the eye of the sewing needle when sewing is resumed. Never do.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a sewing machine having a thread cutting mechanism and a tension releasing mechanism.

First, the thread tension mechanism 1 for applying a resistance to the upper thread Ns fed from a thread spool (not shown) and the tension releasing mechanism 2 for removing the resistance will be described.

Except that a spring rotation restricting mechanism 154 is added to the thread tension mechanism 1, the thread tension mechanism 1 has the same structure as an existing general thread tension mechanism, and thus will be described briefly.

As shown in FIG. 1 to FIG.
A pivot member 10 is fixed to a portion of the machine frame 5 at the front end of the head 8, and a thread tension shaft 15 is attached to the pivot member 10 so as to be movable in the front-rear direction. A tension plate 11, a movable thread tension plate 12, a cap-shaped spring rotation restricting member 155, and a compression spring 13 are externally fitted, and a needle thread Ns is provided at a front end of the pivot support member 10.
An adjusting knob 14 for adjusting the resistance force applied to the spring is screwed. The compression spring 13 is provided over the adjusting knob 14 and the spring rotation restricting member 155. However, the movable thread tension disc 12 and the spring rotation regulating member 155 cannot rotate with respect to the pivot support member 10, and the spring force of the spring 13 is reduced by rotating the adjustment knob 14 clockwise or counterclockwise. A pair of thread tension plates that change
The resistance acting on the upper thread Ns sandwiched between 11 and 12 is adjusted. The fixed thread tension plate 11 is engaged with the step of the pivotal support member 10 from the front, and the portion in front of the step of the pivotal support member 10 is the third portion.
As shown in the figure, the movable thread tension plate 12 is divided into divided slits 10b by divided slits 10b extending in the axial direction.
Is formed, the front end of the thread tension shaft 15 is in contact with the input portion 12a, and the thread tension shaft 15 is moved forward against the spring force of the compression spring 13. The movable thread tension plate 12 is separated from the fixed thread tension plate 11 so that the resistance applied to the upper thread Ns is released.

On the rear side of the fixed thread tension tray 11, a coil spring portion at the base end of the thread take-up spring 151 is accommodated in a spring accommodating space in the pivot support member 10, and the end thereof is fixed to the pivot support member 10, and the pivot support member
Thread take-up spring 15 from the circumferential slit opening formed in 10
1 is extended to the outside, and the leading end of the thread take-up spring 151 is projected upward.
Threading portion bent in a substantially U-shape in plan view at a position facing
152 are formed. A locking member 156 fixed to a later-described spring rotation restricting member 155 is provided at a distal end of the thread take-up spring 151.
A contact portion 153 that contacts the locking portion 157 is provided. The thread hook 152 is constantly urged by a spring force so as to be in the operation position indicated by the solid line in FIG. Therefore, when the upper thread Ns is supplied to the yarn catcher 32 by the lowering of the balance 150, the thread hooking section 152 moves to the operating position to absorb the slack of the upper thread Ns, and the upper thread Ns Is a thread catcher 32
When it is picked up from above, the upper thread Ns is elastically deformed to the inoperative position shown by the broken line in FIG.

On the rear side of the thread tension shaft 15, a cam driven shaft 15A is supported by the machine frame 5 so as to be able to move back and forth. The front end of the cam driven wheel 15A abuts the rear end of the thread tension shaft 15, and the rear end is a pin 9 And abuts on a cam portion 17 of a cam plate 16 pivotally attached to the machine frame 5. The cam portion 17 has an operating portion that pushes the cam driven shaft 15A forward, and a step-down portion that drops down from the operating portion. The drive section 18 of the cam plate 16 is connected to a thread loosening solenoid 20 via a connecting rod 19.
Is connected to the plunger 21. The thread loosening solenoid 20 is fixed to the machine frame 5 by a bracket 22, and the plunger 21 is constantly urged to the left in FIG. Therefore, when the thread loosening solenoid 20 is not energized, the cam driven shaft 15A abuts the stepped portion of the cam portion 17 and does not push the thread tension shaft 15 forward, so that the movable thread tension plate
The spring 12 and the spring rotation restricting member 155 are held at a pressing force applying position indicated by a solid line in FIG. 2, and a resistance adjusted by the adjusting knob 14 is applied to the upper thread Ns. However, when the thread loosening solenoid 20 is energized, the connecting rod 19 moves rightward in FIG. 1, the cam plate 16 rotates clockwise, and the cam driven shaft 15A
7 to push the thread tension shaft 15 forward, the movable thread tension plate 12 moves to the tension release position, the spring rotation restricting member 155 moves to the forward position, and the movable thread tension plate 12 The resistance applied to the upper thread Ns at a predetermined distance from the fixed thread tension tray 11 is released.

Next, the rotation restricting mechanism 154 for holding the thread take-up spring 151 at the inoperative position will be described with reference to FIGS.

A thread take-up spring 151 is provided on the outer cylindrical portion of the spring rotation restricting member 155.
The base end of the locking member 156 for regulating the rotation of
It is fixed with. The distal end of the locking member 156 is located near the right side of the contact portion 153 of the thread take-up spring 151 moved to the inoperative position. The abutting portion against which the abutting portion 153 of the thread take-up spring 151 abuts when it is switched to the forward position after being switched to
157 and a notch 158 that allows the contact portion 153 to pass when the spring rotation restricting member 155 moves to the retracted position.

Therefore, when the thread take-up spring 151 rotates to the inoperative position and the spring rotation restricting member 155 moves to the forward position, the contact portion 153 contacts the locking portion 157 to move the thread take-up spring 151 to this inoperative position. On the other hand, when the spring rotation restricting member 155 moves to the retracted position, the contact portion 153 freely passes through the cutout portion 158, and the thread take-up spring 151 can be elastically deformed between the inoperative position and the inoperative position. become.

Next, the thread cutting mechanism 3 for cutting the upper thread Ns and the lower thread Bs will be described. Since this is the same as that described in JP-A-56-139793, it will be briefly described.

As shown in FIG. 4 and FIG.
A needle plate 27 having a needle hole (not shown) through which is inserted is mounted. A lower shaft 28 is rotatably supported on the machine frame 5 below the needle plate 27, and a left end of the lower shaft 28 Sword point 29, outer pot 30, and inner pot
A bobbin case 33 for accommodating a bobbin (not shown) is provided with a full-rotation type thread ring catcher 32 generally called a shuttle having
The upper thread Ns and the lower thread Bs are entangled with each other in cooperation with the vertical movement of the sewing needle 24 to form a stitch on the work cloth W.

A fixed blade 34 is screwed to the machine frame 5 on the front side of the thread catcher 32 at a substantially front half thereof, and a rear half of the fixed blade 34 is located in the vicinity of the needle hole of the needle plate 27 along the thread catcher 32. It extends in a circular arc shape, and a blade portion 35 is formed at the tip thereof. Reference numeral 36 denotes an inner hook stopper for restraining rotation of the inner hook 31, and reference numeral 37 denotes a fixed blade when the upper thread Ns detached from the blade point 29 during sewing is pulled up.
This is a shielding plate that prevents entanglement with 34.

A movable blade holder 38 is rotatably supported on the machine frame 5 on the rear side of the thread catcher 32 so that the movable blade holder 38 can reciprocate around the same axis as the lower shaft 28. Movable blade on mounting part 39
40 are screwed. A thread separating portion 41, a thread catching groove portion 42, and a blade portion 43 are formed at an arc-shaped left end of the movable blade 40. On the other hand, in order to rotate the movable blade 40, a swing arm 45 is fixed to a swing shaft 44 which is rotated by a cam drive mechanism (not shown), and the swing arm 45 is movable via a connecting lever 46. The connecting portion 47 of the blade holder 38 is connected. Further, in order to drive the cam driving mechanism by rotating the lower shaft 28, the cam driving mechanism is connected to a driving shaft of a thread cutting solenoid 48 (see FIG. 10). Reference numeral 49 denotes a winding spring for urging the swing arm 45 to rotate counterclockwise in FIG. 4 so as to hold the movable blade 40 at the non-cutting position shown in FIG. Accordingly, when the thread trimming solenoid 48 is energized at a predetermined timing at the end of sewing as described later, the rotation of the lower shaft 28 drives the cam drive mechanism and the swing shaft 44 rotates in the direction of the arrow. Moving arm 45
The movable blade holder 38 is rotated clockwise in FIG. 4 via the connecting lever 46, and the movable blade 40 is also rotated clockwise in FIG.
At the timing when the thread ring of the upper thread Ns is disengaged from the blade point 29 of the outer hook 30, the movable blade 40 simultaneously captures the upper thread Ns and the lower thread Bs connected to the work cloth W and engages with the blade portion 35 of the fixed blade 34. And cut it. Here, the length of the cut upper thread Ns from the eye hole 25 of the sewing needle 24 to the thread end (hereinafter, referred to as the upper thread end length) is proportional to the length of the thread catching groove 42. Trench groove
If the length of 42 is reduced, the length of the upper thread end can be reduced.

Next, the upper thread end holding mechanism 51 and the thread holding drive mechanism 52 that hold the upper thread end of the upper thread Ns cut after the sewing is completed will be described.

As shown in FIGS. 6 to 9, a mounting plate 53 is screwed to the rear side of the head 8 of the sewing machine M, and a second solenoid (a bistable latching solenoid) disposed vertically.
54 is fixed to the substantially left half of the mounting plate 53 by a bracket 58, and a first solenoid 59 disposed vertically is fixed to the substantially right half of the mounting plate 53 by a bracket 61. The second solenoid 54 is provided with an upper moving solenoid 55 and a lower moving solenoid 56 (see FIG. 13). When the upper moving solenoid 55 is driven, the plunger 57 moves upward as shown in FIG. (In the direction of arrow U) and is held in the upward movement position,
When the lowering solenoid 56 is driven, the plunger 57 moves down (in the direction of arrow D) and is held at that lowering position. Immediately above the second solenoid 54, a first output link 62 having a substantially U-shape in side view is rotatably supported by a mounting plate 53 with a pin 65 oriented in the front-rear direction. A substantially U-shaped second output link 66 is pivotally supported on the mounting plate 53 by pins 69 oriented in the front-rear direction.

The drive arm 63 of the first output link 62 is pivotally connected to a connecting member 70 fixed to the upper end of the piranger 57 of the second solenoid 54, and the swing arm 64 of the first output link 62 has its length. A pin 74 fixed to the first arm 72 of the substantially L-shaped first link 71 is fitted into the hole 64a and connected to the first link 71. The first link 71 is rotatably supported at its base end by a mounting screw 53 with a stepped screw 76 in the front-rear direction via a spacer 75, and the lower end of the second arm 73 of the first link 71 is The stepped screw 77 is rotatably connected to the right end of the second link 78. The left end of the second link 78 is rotatably connected to the lower end of the third link 80 by a pin 79, and is rotatably connected to the upper end of the fourth link 81. The lower end of the fourth link 81 is a thread. The gripping link member 82 is rotatably connected to the right end of the drive arm 83 by a pin 85.

On the other hand, the drive arm 67 of the second output link 66 has its long hole 67a.
A pin 87 fixed to a connecting member 86 fixed to the lower end of the plunger 57 of the second solenoid 54 is fitted to the connecting member 86, and the right end of the swing arm 68 of the second output link 66 is
At 88, it is rotatably connected to the upper end of the fifth link 89.
The lower end of the link 89 is connected to the first arm 92 of the thread holding link 91 by a pin 90.

A boss 53a in the front-rear direction is fixed to the lower end of the mounting plate 53, and a pivot 94 in the front-rear direction is rotatably supported by passing through the boss 53a and the mounting plate 53. 94
A holder mounting plate 95 is fixed to the front end of the holder, a thread holding holder 96 is screwed to the holder mounting plate 95, and a holding force applying member 97 made of a spring member is screwed to the thread holding holder 96. I have. The distal end portion of the holding force applying member 97 is formed as a downwardly convex curved thread pressing portion 98 (elastic contact portion).

A boss 99 having a step at the rear end of the pivot 94
Is fixedly attached. Therefore, the upward or downward movement of the fifth link 89 causes the yarn holding link to move.
91 rotates counterclockwise or clockwise, and the holding force imparting member 97 is rotated counterclockwise or clockwise in synchronization with the thread holding link 91 via the pivot 94, the holder mounting plate 95, and the thread holding holder 96. Rotate in the direction.

On the other hand, the pivot shaft 94 is inserted through the base end of the drive arm 83 and the base end of the swing arm 84 of the substantially U-shaped thread grasping link member 82 in a plan view, and the thread grasping link member 82 is A thread holding member 100 is screwed to the swing arm 84 so as to be rotatably supported by a pivot 94. Note that reference numeral 102 is a spacer. The front end portion of the thread holding member 100 is formed in an arc shape centered on the pivot 94, and the left end portion of the arc portion captures the upper thread Ns extending downward through the eye hole 25 of the sewing needle 24. A hook portion 101 (yarn catching portion) is formed, and the yarn pressing portion 98 of the holding force applying member 97 elastically abuts a concave portion on the upper surface of the hook portion 101 and cooperates with the hook member 101 to form the upper thread Ns. The end can be held. Accordingly, the yarn gripping link member 82 rotates counterclockwise or clockwise due to the upward or downward movement of the fourth link 81, and the yarn holding member 100 rotates counterclockwise or clockwise. A pivot between the swing arm 84 and the mounting plate 53
One end of a winding spring 103 provided on the 94 is locked to the base end of the thread gripping link member 82, and the other end is locked to a pin 104 fixed to the second arm 93 of the thread holding link 91. The gripping link member 82 is always urged to rotate counterclockwise in FIG. 8 with respect to the thread holding link 91, and the thread holding link 91 is constantly urged clockwise to the thread gripping link member 82. Therefore, the thread presser 98 can reliably contact the hook 101. The drive arm 83 and the swing arm 84 of the thread gripping link member 82 have an opening of about 30 degrees.

A pin 105 in the front-rear direction is fixed to the lower end of the plunger 60 of the first solenoid 59, and a third output link 106 substantially U-shaped in side view is fixed to the lower end of the bracket 61 in a front-rear direction. The third output link 106 is rotatably supported at 109 by a helical spring 110 provided on the pin 109 so that the contact portion 107 of the third output link 106 always contacts the pin 105 from below. Is urged to rotate clockwise. The swing arm 108 of the third output link 106 is the third link 80
Is rotatably connected to an upper end portion of the housing by a pin 111. still,
Reference numeral 26 denotes a needle bar, reference numeral 112 denotes a presser bar, and reference numeral 113 denotes a presser foot.

Next, the operation of the upper thread end holding mechanism 51 and the thread holding drive mechanism 52 will be described with reference to FIGS. 8 and 13 to 16.

When the upward moving solenoid 55 is driven, the plunger 57 moves upward and moves to the upward moving position shown in FIG. 13, and the first output link 62, the first link 71, the second link via the connecting member 70. 7
8, fourth link 81, thread gripping link member 82, thread holding member 100
Respectively move to the solid line positions. The yarn holding member 100 at this time
Is the standby position. On the other hand, as the plunger 57 moves to the upward movement position, the fifth link 89, the thread holding link 91, the holder mounting plate 95, the thread holding holder 96, and the holding force applying member 97 are respectively connected via the connecting member 86. Move to the solid line position.
The position of the holding force applying member 97 at this time is set as a standby position (see FIG. 14). At the standby position, the thread holding member 100 is largely rotated in the counterclockwise direction, and the hook portion 101 is located at a position far above the needle plate 27.

Next, when the lowering solenoid 56 is driven, the plunger 57 moves down and moves to the lowering position shown in FIG. 13, and the first output link 62, the first link 71, The second link 78, the fourth link 81, the thread gripping link member 82, and the thread holding member 100 move to the dashed line positions, respectively. The position of the yarn holding member 100 at this time is defined as a yarn holding position. At this thread holding position, the hook portion 101 of the thread holding member 100 is located near the right side of the sewing needle 24 at the uppermost position. On the other hand, with the downward movement of the plunger 57, the second output link 66 via the connecting member 86,
The fifth link 89, the thread holding link 91, the holder mounting plate 95, the thread holding holder 96, and the holding force applying member 97 are each moved to the dashed line position in FIG. 13 (see FIG. 16). At this time, the thread presser 98 of the holding force applying member 97 can engage with the recess of the hook 101 to hold the upper thread Ns.

In this state, when the first solenoid 59 is driven, the plunger 60 moves down, and the third output link 1
06, third link 80, fourth link 81, thread gripping link member 8
2. The thread holding members 100 move to the two-dot chain line positions in FIG. 13, respectively. At this time, the hook portion 101 of the thread holding member 100 is located near the lowermost position of the sewing needle 24 at the uppermost position, and catches the end of the upper thread Ns extending downward from the eye hole 25 of the sewing needle 24. The position of the yarn holding member 100 at this time is defined as a yarn catching position. When the driving of the first solenoid 59 is stopped, the third output link 106, the third link 80, and the fourth link 8 are driven by the spring force of the winding spring 110.
1.Since the thread gripping link members 82 return to the dashed line positions in FIG. 13 respectively, the thread holding member 100 returns to the thread holding position with the hook 101 capturing the upper thread end, and the holding force. The upper thread end is held in cooperation with the thread presser 98 of the applying member 97 (see FIG. 16).

Further, when the upward moving solenoid 55 is driven, the thread holding member
100 and the holding force imparting member 97 move to the standby positions, respectively, but the second link 78, the third link 80, and the fourth link 81
Immediately after the start of the movement to the standby position, the moving speed of the yarn holding member 100 becomes slower than the moving speed of the holding force applying member 97, and the holding force is applied as shown in FIG. The thread presser 98 of the member 97 comes off the hook 101, and the upper thread end is released. The thread holding member 10 at this time
The position of 0 is the release position.

Next, the overall configuration of the control system of the sewing machine M will be described with reference to the block diagram of FIG.

The thread trimming solenoid 48, the thread loosening solenoid 20, the upper moving solenoid 55, the lower moving solenoid 56, the first solenoid 59, and the sewing machine motor 115 are connected to the drive circuits 116 to 121, respectively, and the respective drive circuits 116 to 121 are controlled. Each is connected to the input / output interface 130 of the device C.

The operation panel 122 is used to set the upper thread loosening timing setting key for setting the loosening timing of the upper thread Ns due to the tension release 2 immediately after the start of sewing by the number of pulses, and the thread end of the upper thread Ns after the needle lower position immediately after the start of sewing. An upper thread release timing setting key for setting the upper thread release timing to be released by the number of pulses is provided, and the pulse number data set by each key operation is output to the input / output interface 130.

The foot pedal 123 has three positions: a front depressed position, a horizontal neutral position, and a rear depressed position, and outputs a sewing machine start command signal (“H” level) as a depressed signal when the operator depresses the front depressed position. , The sewing machine stop command signal (“L” level) is output to the input / output interface 130 when the pedal is depressed to the rear depressed position.

The needle-up signal generator 124 switches the rotation position of a metallic disk member having a small opening formed at a predetermined circumferential position provided on a sewing machine main shaft (not shown) driven by the sewing machine motor 115 to a vicinity switch. And outputs a needle up signal to the input / output interface 130 when the sewing needle 24 is at the uppermost position.
The needle down signal generator 125 is configured similarly to the needle up signal generator 124, and outputs a needle down signal to the input / output interface 130 when the sewing needle 24 is at the lowest position. Also, the pulse signal generator 126
The proximity switch detects the rotational position of a metal disk member formed by forming a large number (for example, 24) of small slits at a predetermined circumferential position provided on a sewing machine main shaft, and rotating the upper shaft by a predetermined angle. A pulse signal is output every time.

The control device C includes a CPU 132 and an input / output interface 13 connected to the CPU 132 via a bus 131 such as a data bus.
0, a ROM 133 and a RAM 140.

The ROM 133 stores a control program for upper thread processing control including upper thread holding control and thread loosening control.

In the thread loosening set pulse number counter 141 of the RAM 140, pulse number data for the set upper thread loosening timing is stored (this content is I). The upper thread release set pulse number counter 142 stores pulse number data for the set upper thread release timing (this content is J). The flag memory 143 stores the neutral position of the foot pedal 123. The flag data of the thread trimming flag F which is set (data is "1") when depressed to the rear depressed position and reset (data is "0") at the end of the thread trimming operation is stored. The needle down signal generator 144 has a needle down signal generator 1
The count value of the needle down signal input from 25
Is stored). Further, the RAM 140 is provided with various memories for temporarily storing the results calculated by the CPU 132.

Next, a routine of the upper thread processing control performed by the controller C of the sewing machine M will be described based on the flowchart of FIG. 11 and with reference to FIGS. However, in order to make the description easy to understand, the description will be made from the time when the foot pedal 123 is depressed to the front depressed position, S1 to S18 are executed, and a series of sewing operations is executed. In the figure, Si (i = 1, 2, 3,...)
Are the steps, and T1 to T11 in FIG. 12 indicate the respective timings.

At the time of T1 during the execution of sewing, the foot pedal 123 is operated from the front depressed position to the rear depressed position through the neutral position, and when the stop command signal of the "L" level is input as the depressed signal, the thread trimming flag is set. F is set (S1
9), when two needle down signals are input from the needle down signal generator 125 and the count value K becomes 2 (S20: Yes, S21, S22: Ye)
s), the thread trimming solenoid 48 and the thread loosening solenoid 20 are each driven (S23). Thereafter, when the sewing machine motor 115 is driven at a low speed and a needle up signal is input from the needle up signal generator 124 (S24: Yes), the drive of the thread trimming solenoid 48 is stopped (S25). When the drive is stopped, the brake in the sewing machine motor 115 is activated by the brake signal, and at T4, the rotation of the sewing machine motor 115, that is, the rotation of the upper shaft is reliably stopped (S26). Then, at the time of T4, the downward moving solenoid 56 is driven for a predetermined time (for example, 60 msec) (S27). Therefore, as described above, the yarn gripping link member 82 and the yarn holding link 91 move from the solid line position in FIG. 13 to the dashed line position, so that the yarn holding member 100 and the holding force applying member 97 are connected to the yarn shown in FIG. Move to the holding position. Subsequently, the first solenoid 59 is driven for a predetermined time (for example, 60 msec) (S28). Accordingly, only the thread holding member 100 moves to the thread catching position, and returns to the thread holding position again with the thread end of the upper thread Ns extending from the eye hole 25 of the sewing needle 24 being caught by the hook portion 101, thereby maintaining the holding force. The upper thread end is held in cooperation with the thread presser 98 of the application member 97. Thereafter, at T5 when the driving of the first solenoid 59 is stopped, the driving of the thread loosening solenoid 20 is also stopped (S29).

Here, an operation of stably stabilizing the length from the eye hole 25 of the sewing needle 24 to the upper thread end held by the thread holding member 100 will be described.

When the upper thread Ns is cut at T2, the upper thread Ns is supplied to the movable blade 40 via the thread hooking section 152 by the movement of the movable blade 40, so that the thread hooking section 152 is Moves from the working position to the non-working position due to the sliding friction. At this time, since the spring rotation restricting member 155 is moved to the forward position by the driving of the thread loosening solenoid 20, the contact portion 153 is at a position facing the locking portion 157. When the upper thread Ns is cut, the contact portion 15
3 is locked by the locking portion 157, and the thread take-up spring 151 is held at its inoperative position. As a result, since the rotation of the thread take-up spring 151 is restricted to the inoperative position, the length of the upper thread end from the eyelet 25 to the upper thread end becomes uniform regardless of the type of the upper thread Ns.
On the other hand, even if the drive of the thread loosening solenoid 20 is stopped while the upper thread end is being captured by the drive of the first solenoid, the upper thread Ns is transferred by the upper thread end holding mechanism 51 and the thread tension mechanism 1. Since each of them is held, the thread take-up spring 151 is held at its inoperative position.

In order to start sewing, when the foot pedal 123 is operated to depress the front stepping position at T6 (stepping signal is "H" level) (S2: Yes), the control device C
The first timer M1 provided within the predetermined time t1 (for example, 10
0 msec) is stored and the counting is started (S3). At T7 when the predetermined time t1 has elapsed (S4: Yes), the sewing machine motor 115 is driven at a low speed by the sewing machine motor drive signal (S4).
5) The set thread loosening set pulse number data N is stored in the counter I (S6), the thread loosening solenoid 20 is driven (S7), there is no input of the stop command signal, and the needle down signal generator
When the first needle down signal is input from 125 (S8: No,
(S9: Yes), the set upper thread release set pulse number data M is stored in the counter J (S10), and each time a pulse signal is input, both count values I and J are decremented by one (S11: Yes S12). At the time T8 when the count value J becomes "0", for example, the sewing needle 24 descends from the uppermost position to form a loop of the upper thread Ns, and the entanglement (knot) of the upper thread Ns and the lower thread Bs is formed. (S13: Yes), the upward solenoid 55 is driven for a predetermined time (for example, 60 msec) (S14). At this time, the yarn holding member 100 and the holding force applying member 97 are in the released position (see FIG. 15) of the yarn holding member 100 immediately after the movement from the yarn holding position shown in FIG. 16 to the standby position in FIG. Sometimes the upper thread end is released. After that, T9 when the count value I became “0”
When, for example, sewing is performed for several stitches, the upper thread Ns and the lower thread are
When Bs is surely confounded (S15: Yes, S16, S17:
Yes), the drive of the thread loosening solenoid 20 is stopped, and the sewing machine motor 115 is driven at a high speed (S18), and the sewing is continued continuously.

Here, the operation of the upper thread Ns not falling out of the eyelet 25 at the time of starting sewing will be described.

Simultaneously with the start of sewing, the thread loosening solenoid 20 is driven, the spring rotation restricting member 155 moves to the forward position, and the thread take-up spring 151 at the inoperative position is continuously held at the inoperative position. Therefore, since the thread take-up spring 151 does not rotate to the operation position, the first and subsequent stitches are sewn while the length of the upper thread end is kept constant, and the upper thread Ns does not fall out of the eye hole 25.

In this way, the upper thread end of the upper thread Ns cut at the end of sewing is held at the thread holding position near the side of the sewing needle 24 located at the uppermost position by the thread holding mechanism 51, and the upper thread end is sewn. Since the thread is held from the start until the confounding of the upper thread Ns and the lower thread Bs is formed, the end of the upper thread Ns moves to the back side of the fabric W by the sewing operation of the second and subsequent stitches as shown in FIG. It does not remain on the front side, and the upper thread end does not become entangled with the lower thread Bs in a bird's nest shape, eliminating the need for thread picking work, significantly improving the sewing product quality at the start of each sewing. it can.

On the other hand, at T10 immediately after the start of sewing in which S1 to S7 have been executed, a stop command signal is input to confirm the needle drop position (S8: Yes). When the needle down stop command is input (S30: Yes), the upper thread release set pulse number data M is temporarily stored in the counter J (S31). The signal counting operation is stopped (S32), the driving of the sewing machine motor 115 is stopped, and the rotation of the upper shaft is stopped at T11 by the brake operation (S33). That is, at this time, the yarn holding member 1
00 is held at the thread holding position while holding the upper thread end. Thereafter, when the start-up of the sewing machine motor 115 is resumed (S3
4: Yes), the sewing machine motor 115 is driven at a low speed (S35),
A predetermined time (for example, 10 msec) is stored in a second timer M2 provided in the control device C (S36), and when the second timer M2 times out (S37), S14 and subsequent steps are executed and sewing is started. You.

As described above, when the needle down stop command for the sewing machine motor 115 is input at the start of the start of the sewing machine motor 115, the counting of the pulse signal with respect to the counter J for releasing the upper thread is stopped, and the thread holding member is further moved. Since the upper thread end is held at the thread holding position for a predetermined time after the restart of the motor 115, the set number of pulses for moving the thread holding member 100 to the standby position after the start of sewing is small. Even when set to a value, the needle thread end is securely held by the thread holding member 100 when the needle lowering is stopped, and the needle thread Ns may come off from the eye hole 25 of the sewing needle 24 when sewing is resumed. Absent.

It should be noted that the thread tension mechanism 1, the tension release mechanism 2, and the thread trimming mechanism 3 in the above-described embodiment are merely examples, and it is a matter of course that various known structures can be used instead of these. Thread holding drive mechanism 52 and upper thread end holding mechanism
51 is only an example, and various existing ones are, of course,
It goes without saying that various modifications and alterations of the embodiment are used.

A supplementary description will be given of the correspondence between each means described in the claims and the components described in the embodiments.

What corresponds to the thread holding driving means is the thread holding driving means 52. In particular, the second solenoid 54 including the upper moving solenoid 55 and the lower moving solenoid 56 of the thread holding driving mechanism 52, The first solenoid 59 corresponds to this. An equivalent to the pulse signal generating means is the pulse signal generator 126 and the like. What corresponds to the yarn holding control means is the flowchart in FIG. 11 (however, except for S30 to S37) and the control device C for achieving the same. Those corresponding to the command control means are S8 and S30 to S37 in the flowchart of FIG. 11 and the control device C for achieving the same.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention. FIG. 1 is a front view of an arm portion of a sewing machine partially cut away, FIG. 2 is a partial side view of the sewing machine, and FIG. FIG. 4, FIG. 4 is a partial longitudinal sectional side view of a bed portion, FIG. 5 is a partial perspective view of a thread catcher and a thread cutting device, FIG. 6 is a partial side view of a thread holding drive mechanism, FIG. Is a side view of the drive mechanism for holding the yarn and the upper end holding mechanism, FIG. 8 is a sectional view taken along the line VIII-VIII of FIG. 7, FIG. 9 is a sectional view taken along the line of FIG. 8 IX-IX, and FIG. FIG. 11 is a schematic flowchart of a routine of upper thread processing control including upper thread holding control and thread loosening control, FIG. 12 is a time chart of various signals, and FIG. 13 is upper thread end holding. Mechanism diagram of the mechanism and the drive mechanism for holding the yarn, FIG. 14 to FIG.
FIG. 16 is a partial front view showing each state of the yarn holding mechanism, and FIG.
FIG. 17 is an enlarged sectional view of the cloth showing the thread end of the upper thread at the sewing start portion, and FIGS. 18 and 19 are each a diagram corresponding to FIG. 17 according to the prior art. 1 Thread tension mechanism 2 Thread tension release mechanism 3 Thread trimming mechanism 11 Fixed thread tension plate 12 Movable thread tension plate 15
… Thread tension shaft, 15A… Cam driven shaft, 20… Thread release solenoid, 30… Outer hook, 31… Middle hook, 34… Fixed blade, 40…
Movable blade, 48: Thread cutting solenoid, 51: Upper thread end holding mechanism, 52: Thread holding drive mechanism, 54: Second solenoid, 55: Upward solenoid, 56: Downward solenoid, 59
... 1st solenoid, 71 ... 1st link, 78 ... 2nd link, 80 ... 3rd link, 97 ... holding force giving member, 100
…… Thread holding member, 126 …… Pulse signal generator, 132 …… CP
U, 133: ROM, 140: RAM, 142: Upper thread release set pulse number counter, C: Control device.

Claims (1)

(57) [Claims] A sewing machine driven by a sewing machine motor via an upper shaft; a balance vertically driven in synchronization with the sewing needle; a shuttle for interlacing an upper thread and a lower thread; a needle in response to a thread trimming command; A thread cutting mechanism for automatically cutting the upper thread and the lower thread between the plate and the shuttle,
A thread tension mechanism for applying resistance to the upper thread between the thread supply source and the balance, a tension release mechanism for releasing the resistance applied to the upper thread by the thread tension mechanism, and a sewing needle located at the uppermost position Can be moved between a position capturing position near the bottom of the sewing needle, a thread holding position near the side of the sewing needle located at the uppermost position, and a standby position located above the thread holding position and opening the upper thread end. An upper thread end holding mechanism having a thread holding member and a holding force applying member for holding the upper thread end in cooperation with the thread holding member at the thread holding position; and a thread holding member of the upper thread end holding mechanism. A sewing machine with an automatic thread trimming mechanism operatively connected to the thread holding member for selectively switching the thread holding member to the three positions, wherein a pulse signal is generated every time the upper shaft rotates a predetermined angle. Pulse signal generating means for outputting, and the end of the thread trimming operation of the thread trimming mechanism. After the completion, the thread holding member is moved from the standby position to the thread holding position via the thread catching position, and the thread holding member is moved when a predetermined number of pulse signals output from the pulse signal generating means are started after the start of the sewing machine motor. A thread holding control means for controlling a thread holding driving means so as to move to a standby position; and stopping a counting of the pulse signal when a needle down stop command for the sewing machine motor is inputted at the start of the start of the sewing machine motor. A sewing machine with an automatic thread trimming mechanism, further comprising command control means for instructing the thread holding control means to position the thread holding member at the thread holding position for a predetermined time from the restart of the start of the sewing machine motor.