JPH0773636B2 - Upper thread feeder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a needle thread feeder for a sewing machine.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 20, a needle thread supply device of this type includes a yarn feeding means 1, a first yarn gripping means 2 arranged before the yarn feeding means, and a yarn feeding means. The second yarn gripping means 3 arranged at the rear stage. As shown in FIG. 21, the yarn feeding means comprises a driving roller 4 and one driven roller 5 which can come into contact with the driving roller 4. The driven roller is supported by the lever 6 and is pressed against the drive roller by the spring 7. The first and second thread gripping means are composed of a magnet 8 and a gripping plate 12 which is supported by a shaft 9 of the magnet and can grip an upper thread 11 between a body 10 of the magnet. The upper thread 11 is pulled out from the spool 13 and passes through the first thread gripping means 2, then between the driving roller 4 and the driven roller 5, and then through the second thread gripping means 3 toward the unillustrated balance. , Through this balance to a needle not shown.

[0003]

However, the conventional technique as described above has a drawback that the yarn is unnecessarily fed when the power of the sewing machine is turned on and off.

SUMMARY OF THE INVENTION An object of the present invention is to provide a practically useful needle thread feeder which overcomes the above-mentioned drawbacks of the prior art.

[0005]

In order to achieve the above-mentioned object, the present invention has a drive roller which is always rotated when a power source is turned on and a driven roller which is arranged to be connectable to the drive roller. And a yarn feeding means having a latch electromagnet on the driven roller, a yarn holding means arranged on the yarn supply source side of the yarn feeding means, and a control means for controlling the yarn feeding means and the yarn holding means. The control means controls the thread gripping means to grip the thread when the power of the sewing machine is turned on and off, and controls the latch electromagnet so that the driven roller is separated from the driving roller.

[0006]

Operation: When the power of the sewing machine is turned on and off, the sewing machine operates so as to grip the thread and not send the thread.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Referring to FIGS. 1 to 4, there is shown a needle thread feeder according to the present invention. This device is applied to a two-needle sewing machine in the illustrated embodiment. The needle thread feeder includes a first frame 20 fixed to a sewing machine main body (not shown) and a second frame 21 movably attached to the first frame. In the first frame, the thread reeling means 22, a plurality of first thread gripping means 23, 23 'arranged in the preceding stage of the thread reeling means, and a second thread gripping means 24 arranged in the latter stage of the thread reeling means. And are installed. The yarn feeding means pulls out the respective upper yarns for two needles by a predetermined amount from a bobbin (not shown). More specifically, the yarn feeding means 22 comprises a driving roller 25 and two driven rollers 26a and 26b which are arranged side by side along the axial direction of the driving roller and are arranged so as to be able to contact the driving roller. . One driven roller 26a grips the first needle thread 27a (shown by the solid line in FIG. 3) between the driven roller 26a and the drive roller 25 and pulls this upper thread from the bobbin by a predetermined amount, and the other driven roller 26b drives the drive roller. Second upper thread 27b between
The upper thread (shown by the broken line in FIG. 3) is grasped and this upper thread is pulled out from the bobbin by a predetermined amount.

The drive roller 25 is rotated by a motor (not shown), and the rotation of this motor is controlled by the control means described later.

The driven rollers 26a and 26b are supported by a lever 28. One end of this lever is swingably attached to the first frame 20 by a shaft 29. The driven rollers 26a and 26b are bearings 28 formed on the lever.
It is rotatably attached to a.

A driven roller drive means is provided at the other end of the lever. The driven roller driving means is for pressing the driven roller against the driving roller or for separating the driven roller from the driving roller. In the illustrated embodiment, the driven roller driving means drives the lever 30 so as to urge the lever so that the driven roller is pressed against the driving roller and the lever so as to separate the driven roller from the driving roller against the spring 30. And a latch electromagnet 60 (shown schematically in FIG. 12). One end of the spring 30 is attached to the other end (free end) of the lever 28, and the other end of this spring is attached to the spring support member 31. This spring support member has a slot 31a extending in the vertical direction when viewed in FIGS. The spring support member is movably secured to the second frame by a screw 32 inserted into the slot and screwed into the second frame. By loosening the screw 32 and moving the spring support member in the vertical direction, the spring pressure can be changed to change the pressure with which the driven roller is pressed against the drive roller.

In the above embodiment, two driven rollers are supported by one lever 28, but as shown in FIG.
Alternatively, each of the two driven rollers may be supported by each of the first and second levers 33a and 33b that are independently arranged. In this case, the driven roller driving means as described above is provided on each of the first and second levers. Therefore, these levers can be operated independently.

The driven roller driving means described above is controlled by the control means described later.

Controlling each of the driven rollers independently is particularly effective in individually feeding out the upper thread to be fed to each needle, when sewing is performed using a plurality of needles. That is, each of the levers is operated to drive the driven rollers 26a, 26b.
It is possible to control so that, for example, one upper thread is fed and the other upper thread is not fed by bringing each of the above into contact with or away from the drive roller 25. Separately from this, in a mode in which two driven rollers are supported by one lever 28 (see FIG. 1), each of the plurality of first thread gripping means is controlled by the control means to change the feeding of the two upper threads. You can also First and second yarn gripping means 23, 2
In the illustrated embodiment, 3'and 24 are electromagnet gripping mechanisms. This electromagnet gripping mechanism has an electromagnet 34 and a grip plate 35 driven by this electromagnet. The electromagnet 34 includes a main body 34a, a magnetic field generating means (not shown) housed in the main body, and a shaft 34b supported by the main body so as to be linearly movable and driven by the magnetic field generating means. Grip plate 35
Is supported at the tip of this shaft. The upper thread is the main body 3
It is inserted between the end face of 4a and the grip plate. The electromagnet is controlled by the control means described later. When the electromagnet is biased and the grip plate is moved toward the main body, the needle thread is gripped between the grip plate and the end surface of the body, and when the grip plate is separated from the body, the needle thread is released.

The yarn feeding means and the first and second yarn gripping means are not limited to those in the above embodiment.

The second frame 21 is arranged substantially parallel to the first frame with a space (see FIGS. 1 and 2). This second frame is a movable support means 3
It is attached to the first frame by 6. The movable support means has a plurality of guide shafts 37, one end of which is fixed to the first frame 20. The second frame is provided with a hole 38 into which the guide shaft is inserted. Bolts 39 are screwed into the other end of the guide shaft 37, and a compression spring 40 is arranged between these bolts and the surface of the second frame. The assembly sequence is briefly described. First, the first frame fixes the guide shaft. Hole 38 in the second frame
Attach it to the first frame by inserting the guide shaft into it. Then, insert the compression spring 40 into the guide shaft,
Finally screw the bolt into the guide shaft. Thus, as shown in FIG. 1, the second frame 21 can be movably attached to the first frame 20 in the direction indicated by the arrow Y.

First to fifth yarn guide members 41 to 45 are attached to the surface of the second frame 21 opposite to the first frame. First and second yarn guide members 41, 42
One threading hole 46 is provided in each of the two, and two threading holes 46 are provided in each of the third to fifth thread guiding members 43 to 45.

The first thread guiding member 41 guides the first upper thread 27a from the thread wound bibon through the threading hole 46 thereof. The first upper thread 27a passing through the first thread guiding member 41 passes between the end surface of the main body 34a of the electromagnet of the one first thread gripping means 23 and the grip plate 35, and then the third thread 27a. It passes between one driven roller 26a and the driving roller 25 through one threading hole of the thread guiding member 43,
Then, it passes through one of the thread passing holes 46 of the fourth thread guiding member 44, then between the end surface of the body of the electromagnet in the second thread gripping means 24 and the grip plate, and then the fifth thread guiding member. It passes through one threading hole 46 of 45, and then reaches one needle (not shown) through a balance not shown.

The second thread guide member 42 guides the second upper thread 27b from the thread winding bobbin through the threading hole 46 thereof. The second upper thread 27b that has passed through the second thread guiding member 42 passes between the end surface of the electromagnet of the other first thread gripping means 23 'and the grip plate, and then the third thread guiding member. The other driven roller 2 through the other threading hole of 43
6b and the drive roller 25, then the other thread passing hole 46 of the fourth thread guiding member 44, and then between the end surface of the electromagnet of the second thread gripping means 24 and the grip plate. Next, the other thread passing hole 4 of the fifth thread guiding member 45
6 and then to the other needle (not shown) via a balance (not shown).

Briefly describing the supply of the upper thread, first, the first and second thread gripping means 23, 23 'and 24 keep the respective upper threads released, and the driving roller 25 and the driven roller 26a. 26b and the upper thread 27a, 27b are gripped, the drive roller 25 is rotated by an appropriate amount to feed out a predetermined amount of the upper thread to be supplied to the needle. After this feeding, the first yarn gripping means 23, 23 'grips the upper thread, and the second yarn gripping means 24 releases the upper thread, and sends the fed upper thread to the needle by the balance. After this upper thread is sent to the needle, the second thread gripping means 24 grips the upper thread. This prevents excess needle thread from being supplied to the needle.

For the convenience of threading, driving means is provided for driving the second frame toward and away from the first frame in the direction of arrow Y. This drive means is the first frame 2 in the illustrated embodiment.
It is composed of a bracket 46 fixed to 0 and an elliptical cam 47 rotatably attached to the bracket and arranged between the first frame 20 and the second frame 21. This cam can be manually rotated by a knob 48. As shown in FIG. 2, the short diameter portion 47a of the cam is arranged between the first frame and the second frame at the time of sewing (FIG. 1), and at the time of threading (FIG. 3), as shown in FIG. As shown, the long diameter portion 47b is arranged between the first frame and the second frame.

At the time of sewing, as shown in FIG. 1, the upper thread is in a state of being supplied to the needle through the respective thread guide members, the first and second thread gripping means, and between the driving roller and the driven roller. From this state, when the knob 48 is rotated clockwise as shown by the arrow in FIG. 2, the cam 47 rises and the second frame 21 is separated from the first frame 20 against the compression spring 40. To bring it into a threading state as shown in FIG. In this state, the upper thread is, as shown in FIG. 3, a thread feeding means 22 and first and second thread gripping means 23, 23 ',
It separates from 24 and passes only the threading holes 46 of the first to fifth thread guiding members 41 to 45. In this state, it is possible to facilitate threading between the yarn feeding means and the first and second yarn gripping means. In particular, when a knot T (see FIG. 3) is present in the yarn, the thread feeding means is shown in FIGS. 9 and 10. As shown, the threading of the first and second thread gripping means is facilitated.

When the knob 48 is rotated counterclockwise as shown by the arrow from the threading state of FIG. 4, the cam rotates from the long diameter portion to the short diameter portion, and therefore the second frame 21 is compressed by the compression spring. By the pressing force of 40, it can approach toward the 1st frame 20, and can bring it to the sewing state shown in FIG. At this time, the upper thread automatically engages with the first and second thread gripping means and the thread delivering means.

As described above, the needle thread can be easily engaged with or disengaged from the first and second thread gripping means and the thread feeding means by operating the knob 48.

Referring to FIGS. 5 and 7, there is shown another embodiment of the needle thread feeder according to the present invention. The upper thread supply device in this embodiment has a plurality of driven rollers arranged along the feeding direction of the upper thread 27a (27b). In the illustrated embodiment, two driven rollers 50, 50 'are arranged. It should be noted that this embodiment is not necessarily limited to the two upper threads, and can be applied to one upper thread. These driven rollers are rotatably supported by the bearing portion 51a of the lever 51. The structure of the lever 51 can be the same as that of the lever 28 except for the bearing portion 51a. or,
Similar driven roller driving means is provided.

When a plurality of driven rollers are arranged in the needle thread feeding direction as described above, the contact portion between the driven roller and the driving roller 25 becomes a line contact, which is a contact area as compared with the conventional point contact in one driven roller. And the slip of the upper thread is extremely reduced.

In the embodiment shown in FIG. 5, the driven roller is arranged at the upper position of the drive roller substantially evenly distributed from the center of the drive roller to the left and right, but in the embodiment shown in FIG. 6, one driven roller 50 'is provided. The drive roller 25 is arranged substantially on the side. By doing so, the contact area can be further increased. In this case, the driven roller 50
The contact pressure between the driven roller 50 ′ and the driven roller 50 ′ is smaller in the driven roller 50 ′ than in the driven roller 50. Since the driven roller 50 'is disposed on the side of the driving roller, the component force of pressing against the driving roller is
Because it is smaller than. By changing the arrangement of the driven roller with respect to the driving roller in this manner, the pressing force of each driven roller with respect to the driving roller can be changed.

In the embodiment shown in FIG. 7, two driven rollers 5 are used.
A belt 52 is wound around 0, 50 '.
This belt is arranged between the driving roller 25 and the driven roller, and is pressed against the driving roller by the driven roller. In this embodiment, the contact between the driven roller and the driving roller is a linear contact via the belt 52, so that the contact area can be made extremely large.

11 and 12 show an embodiment of the empty chain stitching control. That is, several needles (10
When the needle is sewn, the latch electromagnet 60 of the driven roller driving means is actuated to drive the lever 28 upward against the spring 30 as shown by the arrow in FIG. 12, and thus the driven rollers 26a, 26b. (Or 50, 50 ') separates from the drive roller 25. Therefore, the upper thread is not supplied. Such operation is controllably performed by the control means described later.

In this case, the presence or absence of the sewn product is determined by the cloth detecting means 61.
(See FIG. 11). The cloth detecting means is, for example, in the illustrated embodiment, an optical sensor including a light-emitting body and a light-receiving body mounted on the head end 63 near the needle 62, and a needle plate on which a sewing product is placed or a reflecting plate mounted on a table. Made of assembly. Reference numeral 64 indicates a presser foot.

13 and 14 show an embodiment in which the pressing force of the driven roller against the drive roller is changed depending on the thickness of the upper thread. The needle thread feeder of this embodiment detects the thread thickness, for example, a thread thickness detecting means such as a potentiometer 70 (see FIG. 13) and a spring 3 of the driven roller driving means.
And a spring force adjusting means 71 for changing the pressure of 0.
The spring force adjusting means includes a link 72, an eccentric cam 73 arranged so as to contact the link, and a motor (not shown) for driving the eccentric cam. The link 72 has a substantially central portion pivotally attached to the second frame 21 or the sewing machine body, and one end of the spring 30 is attached to one end thereof. The other end of the link contacts the cam surface on the outer circumference of the eccentric cam 73. The motor is controlled by the control means described later. The potentiometer is also connected to this control means.

In brief, the thickness of the yarn is detected by the potentiometer, and the motor is rotated by the control means in response to the detection of the yarn thickness, and the strength of the spring is changed through the eccentric cam and the link. Details will be described later.

FIG. 15 shows an embodiment in which the rotation of the drive roller 25 is accelerated during thread cutting. The upper thread is cut by thread cutting means (not shown). The thread cutting means comprises, for example, a cutter and a thread cutting solenoid that drives the cutter. This thread cutting solenoid is controlled by the control means.

As is apparent from FIG. 15, the drive roller 25
The number of rotations of the motor for driving is set to be high as indicated by the symbol U only when the thread cutting signal C is input. By doing this, the upper thread is fed at high speed while there is a needle thread, and it is possible to secure the necessary thread amount when thread cutting, which requires more thread than in normal sewing, without affecting normal sewing at all. In addition, the upper thread can be reliably cut.

FIG. 16 shows an outline of an embodiment in which the needle thread feeder of the present invention is applied to a sewing machine in which the needle swings. This needle thread feeder is provided with a needle bar amplitude detecting means 81 for detecting the swing width of the swinging needle bar 80. The needle bar amplitude detecting means is connected to the control means described later. The needle bar amplitude detecting means is attached to the needle bar swing base 82. The needle bar amplitude detecting means outputs, for example, the amplitude of the needle of the sewing machine as a digital signal.

FIG. 18 shows an example of the control means 100. In the figure, reference numeral 101 indicates a sewing machine rotation signal generation circuit, and 102 indicates a stop switch connected to the sewing machine rotation signal generation circuit. The sewing machine rotation signal generation circuit generates a "L" signal when the sewing machine is rotating and an "H" signal when the sewing machine is stopped. The stop switch 102 has a function of stopping the operation of the needle thread feeder. Reference numeral 103 denotes a thread trimming signal generating circuit, which is a signal of "L" when the thread trimming solenoid is ON, a signal of "H" when the thread trimming solenoid is OFF, and a signal of "H" when this ON → OFF and a signal "L" when OFF → ON. And output a short pulse. A timer 104 is connected to the sewing machine rotation signal generation circuit 101. This timer is "L" when the sewing machine rotation signal is "L", and the sewing machine rotation signal is "L" →
When it is switched to "H" and a specified time has elapsed, it becomes "H".

The cloth detecting means 61 is connected to the count control circuit 107, and the position detecting means 105 is connected to the count control circuit. The cloth detection means 61 generates a signal "H" when there is a sewn product, and generates a signal "L" when there is no sewn product. The position detecting means 105 is for detecting the upper position, the lower position and the rotation angle of the sewing machine,
A signal "L" is generated during the detection of the upper and lower positions. The count control circuit 107 counts the upper position, the lower position, or the number of stitches of the sewing machine when the cloth detection means 61 is "L" (when there is no sewn product), and when the specified number is counted, the signal becomes "H". When the cloth detecting means outputs the signal "H", the count control circuit becomes the signal "L".

A lower position setting switch 108 is provided. The lower position setting switch invalidates the lower position signal at the output "H" and validates it at "L".

Reference numeral 109 is a latch electromagnet position detecting means, which outputs "L" when the latch electromagnet 60 moves up, that is, when the driven roller is operated to separate the driven roller from the driving roller, that is, when the driven roller moves down. Outputs "H" when is pressed by the drive roller.

The latch electromagnet 60 has a lift actuation circuit 110.
And the lowering operation circuit 111 are connected. Further, a reset signal generating circuit 112 is connected to the ascending operation circuit and the descending operation circuit. When the latch electromagnet 60 is lowered, the raising operation circuit 110 turns ON / OFF the timer 104 and the thread cutting signal generating circuit 103, and the stop switch 10
2. Either "L" of the count control circuit 107 →
The "H" signal raises the latch electromagnet 60.
Further, the reset signal from the reset signal generation circuit 112 unconditionally raises the latch electromagnet. The lowering operation circuit 111 lowers the latch electromagnet by the sewing machine rotation signal of the sewing machine rotation signal generation circuit 101 when the latch electromagnet moves up. It does not operate when the reset signal is input. The latch electromagnet 60, as described above, is driven by the ascending driven roller 26a,
26b (50, 50 ') is raised, and the driven roller is lowered when it is lowered.

The reset signal generation circuit 112 is turned on,
Generates a reset signal when turned off.

The sewing machine speed detecting means 113 is provided, and this detecting means detects the speed of the sewing machine and outputs the frequency as a digital pulse.

A feeding setting means 114 and a feeding detecting means 115 are provided. Latch circuits 116 and 117 are connected to the feeding setting means 114, and the feeding detecting means 115.
A counter circuit 118 is connected to. The feed-out setting means 114 sets the thread feed-out amount of the two upper threads of the driven rollers 26a and 26b during sewing and the thread feed-out amount of the two upper threads at the time of thread cutting. The feeding-out detecting means 115 outputs the yarn feeding amount by a digital pulse. The latch circuit 116 latches the thread feeding setting during sewing between the rotation angle defined by the rotation angle detection signal output from the position detection means 106 and the rotation angle. The other latch circuit 117 turns off the thread cutting signal generation circuit 103 and the thread cutting solenoid.
The ON signal is used to latch the thread feed amount setting during thread cutting. The counter circuit 118 counts and outputs the digital pulses generated by the feeding detection means 115. The count is cleared at a specified angle which is the rotation angle of the position detecting means 106.

A pitch detecting means 119 is provided, which detects the pitch of the sewing machine and outputs it as a digital signal. The pitch detecting means includes an error calculating circuit 12
0 is connected. Further, this error calculation circuit is connected to the latch circuit 116. Needle bar amplitude detection means 8 described above
1 is connected to this arithmetic circuit 120. The error calculation circuit 120 detects the detection signal from the sewing machine speed detecting means 113,
The feed amount is calculated and output by the latched setting signal of the latch circuit 116, the pitch detection output of the pitch detection means 119, and the output of the needle bar amplitude detection means 81.

Error calculation circuit 120 and latch circuit 11
A selection circuit 121 is connected to the switches 6 and 117. This selection circuit outputs the latched design quantity of the latch circuit 117 when the thread trimming signal of the thread trimming signal generation circuit 103 is "L", and outputs the error calculation circuit output when it is "H".

The selection circuit 121 includes comparators 122 and 123.
Are connected, and the comparators 122 and 123 are connected to the counter circuit 118. The comparator 122 compares the output of the counter circuit 118 with the R-side output of the selection circuit 121, and outputs a signal "L" when they are the same. Comparator 1
23 is the output of the counter circuit 118 and L of the selection circuit 121.
The side output is compared, and when they are the same, a signal "L" is output.

Reference numeral 126 indicates a first R electromagnet 127.
Indicates a first L electromagnet. The first R electromagnet corresponds to an electromagnet of one of the two first yarn gripping means,
The first L electromagnet corresponds to the electromagnet of the other yarn gripping means.

An operating circuit 124 is connected to the first R electromagnet 126, and an operating circuit 125 is connected to the first electromagnet 127. These operating circuits 124 and 125 are connected to the reset signal generating circuit 113. Operating circuit 124
Turns on the first R electromagnet when "H" is input, and turns off when "L" is input. It is turned on when the reset signal is input. The operating circuit 125 turns ON the first L electromagnet when “H” is input,
When inputting "L", the value is 0FF. Further, it is turned on when the reset signal is input.

The first R electromagnet 126 controls the thread delivery of the right needle of the two needles, and the first L electromagnet 127 controls the thread delivery of the left needle.

A second electromagnet control circuit 128 for controlling the electromagnet of the second yarn gripping means 24 is provided, an operating circuit 129 is connected to this circuit, and a second electromagnet 130 is connected to this operating circuit. . This second electromagnet corresponds to the electromagnet of the second yarn gripping means. As described above, the second electromagnet clamps the yarn when it is ON, and releases it when it is OFF. The second electromagnet control circuit outputs “H” according to the set rotation angle from the position detection means 106, the set rotation angle signal from the position detection means 106, the thread trimming signal from the thread trimming signal generation circuit 103, The output "L" is generated by either the signal from the latch electromagnet position detecting means 109 or the signal from the stop switch 102. The operating circuit 129 turns on the second electromagnet 130 by inputting "H", and turns it off by inputting "L". It turns ON when the reset signal is input.

A one-needle setting switch 131, a thread breakage detecting means 132, and a linear motor position detecting means 133 are provided. An operating circuit 134 is connected to the one-needle setting switch 131 and the linear motor position detecting means 133, and a linear motor 135 is connected to this operating circuit. This linear motor operates an actuator (not shown) that performs one-needle control to neutral, left, and right positions. The one-needle setting switch is a switch for inputting a needle bar that stops sewing in a one-needle control sewing machine, and there is not 0N at the same time, and the switch input is "L" to be a stop input. The yarn breakage detecting means 132 detects the yarn breakage and sets the output to "L". Normally, when there is no yarn breakage, the output is set to "H". The linear motor position detection means 133 detects the position of the linear motor 135 and outputs it as voltage data. The operating circuit 134 receives the signal from the linear motor position detecting means 133 and operates the linear motor 135 left and right.

A first electromagnet control circuit 136 for controlling the first R electromagnet 126 and the first L electromagnet 127 of the first yarn gripping means is provided. This first electromagnet control circuit is driven to "L" by any one of the signal from the stop switch 102, the signal from the latch electromagnet position detecting means 109, the rotation angle signal from the position detecting means 106, and the OFF → ON signal from the thread trimming signal generating circuit 103. "Output. Also, the comparator 12
It receives "L" signals from 2, 123 and outputs "H".

The frequency generating circuit 13 is provided in the thread trimming signal generating circuit 103, the stop switch 102 and the feeding setting means 114.
7 is connected. Also, the DC motor rotation speed detection means 1
38 is installed, a comparator 139 is connected to this DC motor rotation speed detecting means, a motor control drive circuit 140 is connected to this comparator, and a DC motor 141 is connected to this motor control drive circuit. This DC motor corresponds to a motor that drives the drive roller 25. The frequency generating circuit 137 generates a frequency necessary for the rotation of the DC motor 141 by the thread cutting signal of the thread cutting signal generating circuit 103, the data of the feeding setting means 114, and the input of the stop switch 102. The DC motor rotation speed detection means 138 is D
The frequency of the C motor 141 is output as the frequency of the digital pulse. The comparator 139 compares the inputs from the frequency generation circuit 137 and the DC motor rotation detection means 138, and outputs “H” when the input value from the detection means 138 becomes lower than the input value from the generation circuit 137. , In the opposite case "L"
Is output. The motor control drive circuit 140 accelerates the rotation of the DC motor 141 when "H" is input, and decelerates when the "L" is input.

Presser foot detecting means 142 for detecting the position of the presser foot for pressing the sewing material of the sewing machine is provided, and this detecting means is "L" when the presser foot is raised, that is, the presser foot is lowered. "H" is output when the sewing product is in a state of being held down.

Bias signal generation circuit 1 for selection circuit 121
43 is connected, and this bullying signal generating circuit generates a signal of "L" or "H", and performs a bullying at "L".
The yarn feeding means 22 is controlled so that the normal sewing is performed at "H".

A division calculation number setting means 144 and a division circuit 145 connected thereto are provided. A comparator 146 is connected to this division circuit, and a distributor 14 is connected to this comparator.
7 is connected. The division calculation number setting means 144 determines the division ratio of the division circuit 145. Also, a stop command with a division ratio of ∞ can be set. The division circuit 145 divides R when R is "L" by the input of the one-needle setting switch 131 and outputs it, and when L is "L", divides and outputs L. The division rate is determined by the input of the division number setting means 144. The division rate ∞
Not output when. The comparator 146 compares the output of the counter circuit 118 and the output of the division circuit 145 and outputs "L" when they are the same. The distributor 147 is configured as shown in Table 1.

A one-needle control circuit 148 is provided, and this circuit functions to limit the yarn supply of the stop needle by the input of the one-needle setting switch 131.

Referring to FIG. 16 again, a case where the amount of the upper yarn fed out is controlled according to the swing width of the needle will be described. The feeding-out setting unit 114 controls the yarn feeding-out unit 22 to set the yarn feeding-out amount. The feed-out setting means 114 includes a correcting means 15
0 is connected, a comparator 151 is connected to this correction means, and a pitch amount setting means 152 and a needle thread supply setting switch 153 are connected to this comparator. Further, the needle bar amplitude detecting means 81 is connected to the comparator 151.
Therefore, the needle thread feed amount signal according to the amplitude of the needle by the needle bar amplitude detection means 81 can be given to the feed setting means 114 via the comparator 151 and the correction means 150.

The rotation control means 16 is provided in the delivery setting means 114.
0 and the DC motor 1 via the motor drive control means 161.
By connecting 41, the rotation of the drive roller 25 can be changed stepwise according to the needle feed pitch.

When the power of the sewing machine is turned on or off,
The circuit for holding the upper thread by turning on the electromagnets of the first and second thread gripping means is the operating means 124, 125, the first R electromagnet 126, the first L electromagnet 127, and the actuating circuit in the control means shown in FIG. It is composed of a circuit 129 and a second electromagnet 130. The circuit for separating the driven rollers 26a and 26b from the driving roller 25 when the power of the sewing machine is turned on or off is composed of the ascending operation circuit 110, the descending operation circuit 111 and the latch electromagnet 60. Further, the latch electromagnet 60 outputs an H level to the AND gate via the inverter when an L level signal is generated by the sewing machine rotation signal circuit 101 by the rotation of the sewing machine, and at this time, the rack electromagnet position detecting means 1
09 is an L level output because the latch electromagnet 60 is descending, and since the H level is input to the AND gate via the inverter, the descending operation circuit 111 descends the latch electromagnet 60 by the AND gate output. Let

The one-needle operation will be described again. As shown in FIG. 17, when sewing clothes collar 150 with two needles, longer towards the sewing line 1 ₁ of the other needle (outer) than sewing line 1 ₁ of one of the needle (inside). Therefore, in this case, the sewing line 1 ₂ needs to feed the upper thread more than the sewing line 1 ₁ . In the needle thread feeding device of the present invention, the driven roller that sends the needle thread to the sewing line 1 ₁ can be separated from the drive roller for a certain period of time to reduce the amount of thread unwinding compared to the sewing line 1 ₂ . This is done by controlling the latch electromagnet that drives this driven roller. In addition, the first thread gripping means associated with the sewing line 1 ₁ has a thread gripping timing earlier than that of the first thread gripping means associated with the sewing line 1 ₂ or continues to be gripped for a long time so that the sewing line 1
The _first yarn feed amount can be less than the sewing line 1 _2.

Further, in the needle thread feeder of the present invention, even if the presser foot is raised during sewing, the driven roller and the drive roller can be kept in engagement with each other, that is, in the thread feeding state. This can be done by setting the presser foot detecting means 142 and the first electromagnet control circuit 136 in the yarn feeding state.

The operation of the false stitch will be described again. The shirring signal generation circuit 143 controls the yarn feeding means 22 and the feeding setting means 114 and the first electromagnet control circuit 13.
6 is controlled to set the yarn feeding amount to be smaller than the desired feeding amount. This controls the first R electromagnet 126 and the first L electromagnet 127 by the first electromagnet control circuit so as to grip the yarn earlier than the normal timing, which reduces the yarn feeding amount. When the thread take-out amount is reduced, the thread pulls the sewn product, and the sewn product is bulged.
In this way, the false stitch can be performed.

[0064]

According to the present invention, the upper yarn can be reliably and accurately supplied by the above-mentioned structure, and various upper yarn supply control can be performed by the control means. There is a real advantage that it is possible to provide a superior needle thread feeder. Particularly, according to the present invention, the driven roller is brought into contact with and separated from the power supply when the power is turned on and off.
This prevents the driven roller from being in contact with the drive roller when the power is turned off and on, so that it is possible to prevent unnecessary feeding after the power is turned off, and the driven roller can be held by the operator's fingers before the next turning on. Even if it comes into contact with the drive roller, it is separated again when it is turned on, so there is an advantage that it is possible to prevent the yarn from being fed out when the power is turned on.

[Brief description of drawings]

FIG. 1 is a perspective view showing a sewing state of a needle thread feeder according to the present invention,

2 is a bottom view of FIG. 1,

FIG. 3 is a perspective view of the device of FIG. 1 showing a threading state,

4 is a bottom view of FIG. 3,

FIG. 5 is a front view of the main part showing an embodiment in which a plurality of driven rollers are arranged along the yarn feeding direction,

FIG. 6 is a front view of a main part showing a modified example of FIG. 5;

FIG. 7 is a front view of a main part showing still another modified example of FIG.

FIG. 8 is a side view showing a modified example of the arrangement of driven rollers.

FIG. 9 is a side view showing the knot of the thread during sewing just before passing through the thread gripping means;

FIG. 10 is a side view showing the thread guiding member in a threading state separated from the thread gripping means;

FIG. 11 is a side view of an essential part of the sewing machine head having the cloth detecting means attached thereto;

FIG. 12 is a front view showing an embodiment in which an idler driven roller is separated from a drive roller;

FIG. 13 is a top view of a thread thickness detecting means for detecting the thread thickness,

FIG. 14 is a schematic configuration diagram showing a spring force adjusting means,

FIG. 15 is a graph showing a rise in rotation of the drive roller motor during thread cutting;

FIG. 16 is a schematic configuration diagram showing the arrangement of a needle bar amplitude detection means and a needle,

FIG. 17 is a plan view of a collar portion of a sewn item sewn with two needles.

FIG. 18 is a schematic configuration diagram of control means,

FIG. 19 is a table showing the functions of the distributor,

FIG. 20 is a schematic configuration diagram of a conventional needle thread feeder.

FIG. 21 is a side view of a conventional driven roller.

[Explanation of symbols]

20 first frame 21 second frame 22 thread feeding means 23, 23 'first thread gripping means 24 second thread gripping means 25 drive rollers 26a, 26b driven rollers 27a, 27b needle thread 28 lever 30 spring 60 latch Electromagnet 100 control means

Claims (1)

[Claims] 1. A yarn feeding means having a driving roller which is always rotated when a power source is turned on and a driven roller which is arranged so as to be connectable to the driving roller, wherein the driven roller is provided with a latch electromagnet. A yarn gripping means arranged on the yarn supply source side of the yarn feeding means, a control means for controlling the yarn feeding means and the yarn gripping means,
The control means controls the thread gripping means to grip the thread when the power of the sewing machine is turned on and off, and controls the latch electromagnet so that the driven roller is separated from the driving roller. Yarn feeder.