JP2634523B2 - Needle thread supply device - 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 in a needle thread supply device for a sewing machine.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 20, this type of upper thread supply device includes a thread feeding means 1, a first thread gripping means 2 disposed in front of the thread feeding means, and a thread feeding means. A second thread gripping means 3 disposed at a subsequent stage. As shown in FIG. 21, the yarn feeding means includes a driving roller 4 and one driven roller 5 which can contact the driving roller. The driven roller is supported by a lever 6 and pressed against a driving roller by a spring 7. The first and second thread gripping means include a magnet 8 and a gripping plate 12 supported by a shaft 9 of the magnet and capable of gripping the upper thread 11 between the magnet 10 and a main body 10 of the magnet. The upper thread 11 is pulled out from the bobbin 13 and passes through the first thread gripping means 2, then passes between the driving roller 4 and the driven roller 5, and then passes through the second thread gripping means 3 to a balance (not shown). Through the balance to a needle (not shown).

In this prior art, when the presser foot is raised while the sewing machine is stopped, the driven roller separates from the driving roller, and
It is a configuration that rises.

[0004]

However, in the above-mentioned prior art, there is a possibility that the upper thread cannot be efficiently supplied when the sewing machine is sewn and the thread thickness is different.

Further, since the driven roller rises apart from the driving roller due to the lifting of the presser foot while the sewing machine is stopped, it is necessary to delay the start of the sewing machine until the driven roller comes into contact with the driving roller at the start of the next sewing. There was a drawback that lowering.

SUMMARY OF THE INVENTION An object of the present invention is to provide a practically useful upper thread supply device which solves the above-mentioned disadvantages of the prior art.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for gripping a yarn between a driving roller and a driving roller arranged to contact or separate from the driving roller. A driven roller for feeding the thread, driven roller driving means for driving the driven roller, and control means for controlling the driven roller driving means, wherein the control means is provided when the needle of the sewing machine is at the bottom dead center. Even when the presser foot is raised, the driven roller is kept in contact with the drive roller, and the driven roller drive means is controlled so that the drive roller and the driven roller are separated from each other by raising the presser foot except at the bottom dead center. And

[0008]

The driven roller contacts the drive roller at the bottom dead center of the needle of the sewing machine, and moves away from the drive roller except at the bottom dead center.

[0009]

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

Referring to FIGS. 1 to 4, there is shown a needle thread supply device according to the present invention. This apparatus is applied to a two-needle sewing machine in the illustrated embodiment. The upper thread supply device 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, a thread reeling means 22, a plurality of first thread grasping means 23, 23 'arranged before the thread reeling means, and a second thread grasping means 24 arranged downstream of the thread reeling means. And are attached. The yarn feeding means draws out a predetermined amount of each upper thread for two needles from a bobbin (not shown). More specifically, the yarn feeding means 22 includes a driving roller 25 and two driven rollers 26a and 26b arranged side by side along the axial direction of the driving roller and arranged to be able to contact the driving roller. . One driven roller 26a grips a first upper thread 27a (shown by a solid line in FIG. 3) between the driving roller 25 and pulls out the upper thread by a predetermined amount from the bobbin, and the other driven roller 26b is a driving roller. 25 and the second upper thread 27b
(Shown by a broken line in FIG. 3), the 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 the motor is controlled by 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 connected to a bearing 28 formed on a lever.
a so as to be rotatable.

A driven roller driving 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 separating the driven roller from the driving roller. In the illustrated embodiment, the driven roller driving means drives the lever to bias the lever so that the driven roller is pressed against the driving roller, and drives the lever 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 the spring is attached to a spring support member 31. This spring support member has a slot 31a extending vertically as viewed in FIGS. The spring support is movably secured to the second frame by screws 32 inserted into the slots 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 at which the driven roller is pressed against the drive roller.

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

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

Independently controlling each of the driven rollers is particularly effective for independently feeding the upper thread to be sent to each needle when sewing is performed using a plurality of needles. That is, each lever is operated to drive the driven rollers 26a, 26b.
By making each of them contact or separate from the drive roller 25, for example, it is possible to control so as to feed out one upper thread and not to feed out the other upper thread. 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 feed of the two upper threads. You can also. First and second yarn gripping means 23, 2
Reference numerals 3 'and 24 each comprise an electromagnet gripping mechanism in the illustrated embodiment. This electromagnet gripping mechanism has an electromagnet 34 and a gripping plate 35 driven by the 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. Upper thread is body 3
4a is inserted between the end face and the holding plate. The electromagnet is controlled by control means described later. When the electromagnet is energized and the gripping plate is moved toward the main body, the upper thread is gripped between the gripping plate and the end face of the main body, and when the gripping plate is separated from the main body, the upper thread is released.

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

The second frame 21 is disposed substantially parallel to and spaced from the first frame (see FIGS. 1 and 2). This second frame is a movable support means 3
6 attached to the first frame. The movable support means has a plurality of guide shafts 37 each having one end fixed to the first frame 20. The second frame is provided with a hole 38 into which the guide shaft is inserted. A bolt 39 is screwed into the other end of the guide shaft 37, and a compression spring 40 is disposed between the bolt and the surface of the second frame. To briefly describe the assembling sequence, first, the guide shaft is fixed to the first frame. Hole 38 in the second frame
Insert the guide shaft into and attach it to the first frame. Next, the compression spring 40 is inserted 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.

The second frame 21 has first to fifth thread guide members 41 to 45 mounted on the surface opposite to the first frame. First and second thread guide members 41, 42
Are provided with one threading hole 46, respectively, and the third to fifth thread guide members 43 to 45 are provided with two threading holes 46, respectively.

The first thread guide member 41 guides the first upper thread 27a from the bobbin through the threading hole 46. The first upper thread 27a passing through the first thread guide member 41 passes between the end face of the main body 34a of the electromagnet in the first thread grasping means 23 and the grasping plate 35, and then the third thread 27a. Passing between one driven roller 26a and the drive roller 25 through one threading hole of the thread guide member 43,
Next, it passes through one threading hole 46 of the fourth thread guide member 44, then passes between the end face of the main body of the electromagnet in the second thread grasping means 24 and the grasping plate, and then passes through the fifth thread guide member. 45, and then to one needle (not shown) via a balance (not shown).

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

The supply of the upper thread will be briefly described. First, the first and second thread grasping means 23, 23 ', 24 release the upper thread respectively, and the driving roller 25 and the driven roller 26a, With the upper thread 26b gripping the upper threads 27a and 27b, the drive roller 25 is rotated by an appropriate amount to feed out a predetermined quantity of the upper thread to be supplied to the needle. After this feeding, the first thread gripping means 23, 23 'grips the upper thread, and the second thread gripping means 24 releases the upper thread, and sends the fed upper thread to the needle by a balance. After the upper thread is sent to the needle, the second thread gripping means 24 grips the upper thread. This prevents extra needle thread from being supplied to the needle.

A driving means is provided for driving the second frame closer to or away from the first frame in the direction of arrow Y to provide convenience for threading. This driving means is the first frame 2 in the embodiment shown.
The bracket comprises a bracket 46 fixed at 0 and an elliptical cam 47 rotatably mounted on the bracket and disposed between the first frame 20 and the second frame 21. This cam can be manually rotated by a knob 48. The short diameter portion 47a of this cam is arranged between the first frame and the second frame as shown in FIG. 2 during sewing (FIG. 1), and as shown in FIG. 4 during threading (FIG. 3). As shown, the major diameter portion 47b is disposed 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. When the knob 48 is rotated clockwise as shown by the arrow in FIG. 2 from this state, the cam 47 rises to move the second frame 21 away from the first frame 20 against the compression spring 40. To bring the threading state as shown in FIG. In this state, the upper thread is threaded as shown in FIG. 3 and the first and second thread gripping means 23, 23 ',
24, and passes only through the threading holes 46 of the first to fifth thread guide members 41 to 45. In this state, it is possible to facilitate the threading of the yarn feeding means and the first and second yarn gripping means. In particular, when the knot T (see FIG. 3) exists in the yarn, FIGS. As shown, threading of the first and second thread gripping means is facilitated.

When the knob 48 is rotated counterclockwise from the threading state shown in FIG. 4 as indicated by the arrow, the cam rotates from the long diameter portion to the short diameter portion, so that the second frame 21 is compressed by the compression spring. With a pressing force of 40, the first frame 20 can be approached and brought 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 feeding means.

As described above, the upper thread can be easily engaged or disengaged with 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 upper thread supply device according to the present invention. The upper thread supply device in this embodiment has a plurality of driven rollers arranged in the feed direction of the upper thread 27a (27b). In the embodiment shown, two driven rollers 50, 50 'are arranged. In addition, this embodiment is not necessarily limited to two upper threads and can be applied to one upper thread. These driven rollers are rotatably supported by a bearing 51 a of a lever 51. The structure of the lever 51 can be the same as that of the lever 28 except for the bearing 51a. or,
Similar driven roller driving means is provided.

When a plurality of driven rollers are arranged in the feed direction of the upper thread as described above, the contact portion between the driven roller and the driving roller 25 is in line contact, and the contact area is smaller than the point contact of one conventional driven roller. And the slip of the upper thread is extremely reduced.

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

In the embodiment shown in FIG. 7, two driven rollers 5 are provided.
A belt 52 is wound around 0, 50 '.
The belt is disposed 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 becomes a line contact via the belt 52, so that the contact area can be extremely large.

FIGS. 11 and 12 show an embodiment of the blank ring sewing control. In other words, several stitches (10
In the case of sewing, the latch electromagnet 60 of the driven roller driving means is operated to drive the lever 28 upward against the spring 30 as shown by the arrow in FIG. 12, so that the driven rollers 26a, 26b (Or 50, 50 ′) move away from the drive roller 25. Therefore, the upper thread is not supplied. Such an operation is performed in a controlled manner by control means described later.

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

FIGS. 13 and 14 show an embodiment in which the pressing force of the driven roller against the driving roller is changed according to the thickness of the upper thread. The upper thread supply device in this embodiment includes a thread thickness detecting means for detecting the thread thickness, for example, 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 zero.
The spring force adjusting means includes a link 72, an eccentric cam 73 arranged to be in contact with 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 main 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 periphery of the eccentric cam 73. The motor is controlled by control means described later. The potentiometer is also connected to the control means.

Briefly, the thickness of the yarn is detected by a potentiometer, and the motor is rotated by the control means in response to the detection, and the strength of the spring is changed via 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 trimming. The upper thread is cut by a thread cutting means (not shown). The thread cutting means comprises, for example, a cutter and a thread cutting solenoid for driving the cutter. This thread cutting solenoid is controlled by the control means.

As is apparent from FIG.
Is set so as to increase as indicated by reference numeral U only when the thread cutting signal C is input. In this way, the thread is fed at a high speed while the upper thread is present, and the required thread amount can be secured without any influence on ordinary sewing and at the time of thread trimming requiring a larger number of threads than during normal sewing. In addition, the upper thread can be reliably cut.

FIG. 16 schematically shows an embodiment in which the needle thread supply device of the present invention is applied to a sewing machine of the type in which the needle swings. This needle thread supply device has a needle bar amplitude detecting means 81 for detecting the swing width of the oscillating needle bar 80. The needle bar amplitude detecting means is connected to a control means described later. The needle bar amplitude detecting means is attached to the needle bar swing table 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 denotes a sewing machine rotation signal generation circuit, and reference numeral 102 denotes a stop switch connected to the sewing machine rotation signal generation circuit. The sewing machine rotation signal generation circuit generates a signal of "L" while the sewing machine is rotating and a signal of "H" while the sewing machine is stopped. The stop switch 102 has a function of stopping the operation of the upper thread supply device. Reference numeral 103 denotes a thread cutting signal generation circuit, which is a signal of "L" when the thread cutting solenoid is ON, a signal of "H" when OFF, a signal "H" when ON → OFF, and a signal "L" when OFF → ON. Are output as short pulses. A timer 104 is connected to the sewing machine rotation signal generating circuit 101. This timer is set to “L” when the sewing machine rotation signal is “L”, and the sewing machine rotation signal is changed to “L” →
The state is switched to "H" and becomes "H" after a lapse of a specified time.

The cloth detecting means 61 is connected to a count control circuit 107, and a position detecting means 106 is connected to the count control circuit. The cloth detecting means 61 generates a signal "H" when there is a sewing product, and generates a signal "L" when there is no sewing product. The position detecting means 106 is for detecting the upper position, the lower position, and the rotation angle of the sewing machine,
During the detection of the upper and lower positions, a signal "L" is generated. When the cloth detecting means 61 is "L" (when there is no sewing material), the count control circuit 107 counts the upper position, the lower position, or the number of stitches of the sewing machine. 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, and this lower position setting switch invalidates the lower position signal at the output “H” and makes it valid at the output “L”.

Reference numeral 109 denotes a latch electromagnet position detecting means which outputs an "L" signal when the latch electromagnet 60 moves up, that is, when the driven roller is moved away from the driving roller, and when the latch electromagnet 60 moves down, that is, when the driven electromagnet 60 drops, Output "H" when is pressed by the drive roller.

The latching electromagnet 60 has a rising operation circuit 110
And the descent operating circuit 111 are connected. Further, a reset signal generating circuit 112 is connected to the up operation circuit and the down operation circuit. When the latch electromagnet 60 is lowered, the ascending operation circuit 110 is turned on and off by the timer 104 and the thread cutting signal generation circuit 103, and the stop switch 10
2. Any "L" of the count control circuit 107 →
The latch electromagnet 60 is raised by the “H” signal.
Further, the latch electromagnet is unconditionally raised by the reset signal from the reset signal generating circuit 112. The lowering operation circuit 111 lowers the latch electromagnet according to the sewing machine rotation signal of the sewing machine rotation signal generation circuit 101 when the latch electromagnet rises. It does not operate when a reset signal is input. As described above, the latch electromagnet 60 is driven by the ascending driven roller 26a,
26b (50, 50 ') is raised, and the driven roller is lowered at the time of descent.

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

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

The feeding setting means 114 and the feeding detecting means 115 are provided, and the feeding setting means 114 is connected to latch circuits 116 and 117.
Is connected to a counter circuit 118. The feeding setting means 114 sets the amount of the two upper threads that are driven by the driven rollers 26a and 26b during sewing, and sets the amount of the two upper threads that are threaded when cutting. The feeding detection unit 115 outputs the feeding amount of the yarn as a digital pulse. The latch circuit 116 latches the thread feeding setting during sewing between the rotation angles specified by the rotation angle detection signal output from the position detection means 106. The other latch circuit 117 turns off the thread cutting signal generation circuit 103 and the thread cutting solenoid.
The thread feed amount setting at the time of thread trimming is latched by the ON signal. The counter circuit 118 counts and outputs the digital pulses generated by the feeding detection means 115. The count clear is performed at a specified angle which is the rotation angle of the position detecting means 106.

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

Error calculation circuit 120 and latch circuit 11
6, 117, the selection circuit 121 is connected. The selection circuit outputs the latched design amount of the latch circuit 117 when the thread cut signal of the thread cut 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
And the comparators 122 and 123 are connected to the count circuit 113. The comparator 122 compares the output of the count circuit 118 with the R-side output of the selection circuit 121, and outputs a signal “L” when they are equal. Comparator 1
23 is an output of the count circuit 118 and L of the selection circuit 121.
The output is compared with the side output, and when they are the same, a signal "L" is output.

Reference numeral 126 denotes a first R electromagnet, and 127
Indicates a first L electromagnet. The first R electromagnet corresponds to the electromagnet of one of the two first thread holding means,
The first L electromagnet corresponds to the electromagnet of the other thread holding means.

An operation circuit 124 is connected to the first R electromagnet 126, and an operation 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. Also, it turns ON when a reset signal is input. The operation circuit 125 turns on the first L electromagnet when "H" is input,
Turns OFF when "L" is input. Also, it turns ON when a reset signal is input.

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

A second electromagnet control circuit 128 for controlling the electromagnet of the second thread gripping means 24 is provided, and an operation circuit 129 is connected to this circuit, and a second electromagnet 130 is connected to this operation circuit. . This second electromagnet corresponds to the electromagnet of the second thread gripping means. As described above, the second electromagnet clamps the yarn when turned on, and releases it when turned 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 cut signal from the thread cut signal generation circuit 103, An output “L” is generated by one of the signal from the latch electromagnet position detecting means 109 and the signal from the stop switch 102. The operation circuit 129 turns on the second electromagnet 130 by inputting “H” and turns it off by inputting “L”. It turns ON when a 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 for stopping the sewing in the one-needle control sewing machine, and is not simultaneously turned on but becomes a stop input by a switch input “L”. The yarn break detecting means 132 detects the yarn break and sets the output to "L". Normally, when there is no yarn break, the output is set to "H". The linear motor position detecting means 133 detects the position of the linear motor 135 and outputs it as voltage data. The operation circuit 134 receives the signal of 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 thread gripping means is provided. The first electromagnet control circuit outputs “L” based on one of a signal from the stop switch 102, a signal from the latch electromagnet position detection means 109, a rotation angle signal from the position detection means 106, and an OFF → ON signal from the thread cutting signal generation circuit 103. "Output. Also, the comparator 12
2, 123, and receives an “L” signal and outputs “H”.

The frequency generating circuit 13 is provided to the thread trimming signal generating circuit 103, the stop switch 102 and the feeding setting means 114.
7 is connected. DC motor rotation speed detecting means 1
38, a comparator 139 is connected to the DC motor rotation speed detecting means, a motor control drive circuit 140 is connected to the comparator, and a DC motor 141 is connected to the 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 based on the thread trimming signal of the thread trimming 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 detecting means 138
The rotation number of the C motor 141 is output as a digital pulse frequency. The comparator 139 compares the input from the frequency generation circuit 137 and the input from the DC motor rotation detection means 138, and outputs “H” when the value of the input from the detection means 138 becomes lower than the value of the input from the generation circuit 137. , Or “L” for the opposite
Is output. The motor control drive circuit 140 accelerates the rotation of the DC motor 141 in the case of "H" input, and decelerates in the case of "L" input.

A presser foot detecting means 142 for detecting the position of the presser foot for holding the sewing material of the sewing machine is provided. This detecting means is "L" when the presser foot is raised, and when the presser foot is lowered, "H" is output when the sewing product is held down.

The selection signal 121 is applied to the storm signal generation circuit 1
Reference numeral 43 is connected, and the shirring signal generation circuit generates a signal of "L" or "H", and performs shirring by "L".
At "H", the thread feeding means 22 is controlled so as to perform normal sewing.

A division calculation number setting means 144 and a division circuit 145 connected thereto are provided. A comparator 146 is connected to the division circuit.
7 is connected. The division calculation number setting means 144 determines the division ratio of the division circuit 145. In addition, a stop command for the division ratio ∞ can be set. The division circuit 145 divides and outputs R when R is "L" at the input of the one-hand setting switch 131, and divides and outputs L when L is "L". The division rate is determined by the input of the division calculation number setting means 144. The division rate ∞
No output when. The comparator 146 compares the output of the count circuit 118 with the output of the division circuit 145, and outputs “L” if 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 serves to limit the supply of the thread to the stop needle in response to the input of the one-needle setting switch 131.

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

Rotation control means 16
0 and the DC motor 1 via the motor drive control means 161
The connection of 41 allows the rotation of the drive roller 25 to be changed stepwise in accordance with the needle feed pitch.

When the power of the sewing machine is turned on or off,
The circuit for gripping the upper thread by turning on the electromagnets of the first and second thread gripping means includes the operating circuits 124 and 125, the first R electromagnet 126, the first L electromagnet 127, It comprises a circuit 129 and a second electromagnet 130. When the power of the sewing machine is turned on or off, a circuit for separating the driven rollers 26a and 26b from the driving roller 25 includes an up operation circuit 110, a down operation circuit 111, and a latch electromagnet 60. The advantage of these circuits is that no extra thread is supplied when starting or stopping the sewing machine.

The single-needle operation will be described again. As shown in FIG. 17, when sewing the collar 150 of the clothes with two needles, the sewing line ₁₁ (outside) of _one needle is longer than the sewing line ₁₁ (inside) of the other needle. Therefore, in this case, it must be sent over the thread to extra than sewing line 1 ₁ towards the sewing line 1 _2. In upper thread supply device of the present invention it is possible to reduce the yarn feed amount than the sewing line 1 ₂ a driven roller to send the upper thread is moved away some time from the drive roller to the sewing line 1 _1. This is accomplished by controlling a latch electromagnet that drives the driven roller. Also, sewing the first yarn gripping means associated with the sewing line 1 ₁ Line 1 ₂
It may be less than the first yarn gripping means sewing line 1 ₂ yarn feed amount of the sewing line 1 ₁ or continue to grip long or faster yarn gripping timing than that associated with.

Further, in the needle thread supply device of the present invention, even when the presser foot is raised during sewing, the driven roller and the driving roller can be maintained in the engaged state, that is, the thread unreeling state. This can be performed by setting the presser foot detecting means 142 and the first electromagnet control circuit 136 to the line feeding state.

The operation of shirring will be described again. The shirring signal generating circuit 143 includes a feeding setting means 114 for controlling the yarn feeding means 22 and the first electromagnet control circuit 13.
6 is set so that the yarn feeding amount is smaller than the desired feeding amount. This means that the first electromagnet control circuit controls the first R electromagnet 126 and the first L electromagnet 127 so that the yarn is gripped earlier than usual, thereby reducing the amount of yarn being fed. When the amount of the thread to be fed is small, the thread pulls the sewn material, and the sewn material is sewn.
In this way, the sewn sewing can be performed. That is, when the sewing machine is stopped at the needle down position, an L level is output from the stop switch 102 and the position detection means 106, an L level is also output from the lower position setting switch 108, and the presser foot is further raised. Therefore, the L level is also output from the presser foot detecting means 142, and the NAND gate for inputting those outputs becomes the L level output.
The AND gate is maintained at L level and the ascending operation circuit 10 is maintained.
, The latch electromagnet 60 is maintained in the lowered position.

[0066]

According to the present invention, the supply of the upper thread can be reliably and accurately performed by the above-described configuration, and various control of the supply of the upper thread can be performed by the control means. There is a benefit that a flexible upper thread supply device can be provided. In particular, according to the present invention, even when the presser foot is raised, the driven roller can be maintained at the lowered position, so that there is no disadvantage of delaying the start of the sewing machine as in the related art, and the working efficiency of the sewing machine can be improved. There are advantages.

[Brief description of the drawings]

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

FIG. 2 is a bottom view of FIG. 1;

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

FIG. 4 is a bottom view of FIG. 3;

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

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

FIG. 7 is a front view of a main part showing still another modified example of FIG. 5;

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 sewing thread immediately before passing through the thread gripping means.

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

FIG. 11 is a side view of a main part of the sewing head to which the cloth detecting means is attached.

FIG. 12 is a front view showing an embodiment in which an idle driven roller is separated from a driving roller.

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

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

FIG. 15 is a graph showing an increase in rotation of a motor of a driving roller during thread cutting.

FIG. 16 is a schematic configuration diagram showing an arrangement of a needle bar amplitude detection unit and a needle.

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

FIG. 18 is a schematic configuration diagram of a control unit.

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

FIG. 20 is a schematic configuration diagram of a conventional upper thread supply device.

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

[Explanation of symbols]

 Reference Signs List 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 upper thread 28 lever 30 spring 60 latch Electromagnet 100 control means

Claims (1)

(57) [Claims] 1. A yarn feeder comprising: a drive roller; and a driven roller disposed so as to be able to contact and separate from the drive roller; a yarn feeder provided with a latch electromagnet on the driven roller; A thread gripping means for gripping the thread by arranging it on the side, and releasing or gripping the thread according to the feeding amount while the driven roller is in contact with the driving roller during sewing, and gripping the thread while separating the driven roller during non-sewing. Control means for controlling the thread feeding means and the thread gripping means, the control means comprising: a first detection means for detecting an elevation of a presser foot of the sewing machine; and a second detection means for detecting a stop of the sewing machine at a needle lower position. An upper thread supply device, comprising: two detection means, and controlling to keep the driven roller at the lowered position when detecting the stop of the needle lower position and the rise of the presser foot.