JPH0623174A - Upper thread feeding device - Google Patents

Abstract

PURPOSE:To effectively feed threads by changing pressure to the driving roller of a slave roller corresponding to the thickness of threads. CONSTITUTION:This device is provided with a driving roller 25, slave rollers 26a and 26b arranged so as to be contacted or separated to the driving roller 25 for feeding the thread while clamping the thread with the driving roller 25, spring 30 to energize the slave rollers 26a and 26b so as to contact the driving roller 25, tensile force adjusting means to adjust the tensile force of the spring 30, thread thickness detecting means to detect the thickness of the thread, and control means, and the control means controls the tensile force adjusting means so that the tensile force adjusting means can suitably set the tensile force of the slave rollers 26a and 26b corresponding to the thickness of the thread detected by the thread thickness detecting means.

Description

Detailed Description of the Invention

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.

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 and a yarn feeding means which are arranged upstream of the 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 driving roller 5, and then through the second thread gripping means 3 toward the unillustrated balance. , Through this balance to a needle not shown.

However, in the prior art as described above, there is a possibility that the upper yarn cannot be efficiently supplied when the yarn thickness is different. It is an object of the present invention to provide a practically useful needle thread feeder that overcomes the above-mentioned drawbacks of the prior art.

In order to achieve the above object, the present invention provides a drive roller and a yarn arranged between the drive roller and the drive roller so as to come into contact with or separate from the drive roller. A driven roller for gripping the yarn to feed the yarn, a spring for urging the driven roller to bring the driven roller into contact with the driving roller, a spring force adjusting means for adjusting the spring force of the spring, and the yarn A yarn thickness detecting means for detecting the thickness of the yarn, and a controlling means, wherein the controlling means appropriately adjusts the spring force of the driven roller by the spring force adjusting means according to the thickness of the yarn by the yarn thickness detecting means. The spring force adjusting means is controlled so as to be set.

The pressure of the driven roller against the drive roller is changed according to the thickness of the thread.

Embodiments of the present invention will now be described in detail with reference to the drawings. 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. Driven rollers 26a, 26b
Is supported on the 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 rotatably attached to a bearing portion 28a formed on the lever. 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, the two driven rollers are supported by the one lever 28, but as shown in FIG. 8, the two driven rollers are respectively arranged independently of the first and second levers 33a and 33a.
You may make it support each of 3b. 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 needle thread to be fed to each needle, when performing sewing using a plurality of needles. That is, each lever is operated to drive the driven roller 2
By bringing each of 6a and 26b into contact with or away from the drive roller 25, for example, it is possible to control so that one upper thread is fed and the other upper thread is not fed. Separately, two driven rollers are connected to one lever 2
In the mode supported by 8 (see FIG. 1), it is also possible to control the respective first thread gripping means by the control means to change the feeding of the two upper threads. The first and second thread gripping means 23, 23 ', 24 consist of electromagnet gripping mechanisms in the illustrated embodiment. This electromagnet gripping mechanism has an electromagnet 34 and a grip plate 35 driven by this electromagnet. Electromagnet 3
Reference numeral 4 includes a main body 34a, a magnetic field generating means (not shown) housed in the main body, and a shaft 34b which is linearly movably supported by the main body and driven by the magnetic field generating means. The grip plate 35 is supported by the tip of this shaft. The upper thread is inserted between the end surface of the main body 34a 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).
The second frame is attached to the first frame by movable support means 36. The movable support means has a plurality of guide shafts 37, one end of which is fixed to the first frame 20.
Have. Hole 3 into which the guide shaft is inserted in the second frame
8 are provided. Bolt 3 is attached to the other end of the guide shaft 37.
9 is screwed in and a compression spring 40 is arranged between these bolts and the surface of the second frame. To put the assembly order simply, first, the guide shaft is fixed to the first frame. The second frame is attached to the first frame by inserting the guide shaft into the hole 38. Then, the compression spring 40 is inserted into the guide shaft, and finally the bolt is screwed 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. Each of the first and second thread guiding members 41, 42 has one threading hole 46.
Are provided, 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 winding bobbin 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, and then the fourth thread guiding member 44.
Through one of the threading holes 46, then between the end surface of the body of the electromagnet in the second thread gripping means 24 and the gripping plate, and then one of the threading holes 4 of the fifth thread guiding member 45.
6 and then to one needle (not shown) via a balance not shown. The second thread guiding 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. 43 through the other thread passing hole, and between the other driven roller 26b and the driving roller 25, then through the other thread passing hole 46 of the fourth thread guiding member 44, and then the second thread gripping means. It passes between the end face of the electromagnet at 24 and the grip plate, then passes through the other thread passing hole 46 of the fifth thread guiding member 45, and then reaches the other needle (not shown) via a balance not shown. To briefly describe the supply of the upper thread, first, the first and second thread gripping means 23, 23 ', 24 keep the respective upper thread released, and the driving roller 25 and the driven rollers 26a, 26b are While holding the upper threads 27a and 27b, 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 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 this needle 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. In order to provide convenience for threading, driving means for driving the second frame toward or away from the first frame along the arrow Y direction is provided. This drive means is, in the illustrated embodiment, a bracket 46 fixed to the first frame 20 and an elliptical shape rotatably mounted on this bracket and arranged between the first frame 20 and the second frame 21. It consists of a cam 47. 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 yarn is, as shown in FIG. 3, a yarn feeding means 22 and first and second yarn gripping means 2
It separates from 3, 23 ′ and 24 and passes only through 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 thread feeding means and the first and second thread gripping means, and in particular, a knot T (see FIG. 3) is formed on the thread.
When there is a thread, as shown in FIGS. 9 and 10, threading of the first and second thread gripping means becomes easy. 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 pushes the compression spring 40. The pressure can bring it towards the first frame 20 and bring it to the sewing condition shown in FIG. At this time, the upper thread automatically engages with the first and second thread gripping means and the thread delivering means.
In this way, the needle thread can be easily engaged or disengaged from the first and second thread gripping means and the thread feeding means by operating the knob 48. 5 and 7, another embodiment of the needle thread feeder according to the present invention is shown. The needle thread supply device in this embodiment is a needle thread 27a.
A plurality of driven rollers are arranged along the feeding direction of (27b). In the illustrated embodiment, two driven rollers 5
0 and 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. Further, similar driven roller driving means is provided. When a plurality of driven rollers are arranged in the needle thread feeding direction in this way, the contact portion between the driven roller and the driving roller 25 becomes a line contact, and the contact area becomes larger than the conventional point contact in one driven roller. The slip of the upper thread is extremely reduced. In the embodiment shown in FIG. 5, the driven roller is disposed above the drive roller in a substantially evenly distributed manner 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 replaced by the drive roller 25. It is arranged almost on the side of the. By doing so, the contact area can be further increased. In this case, the driven roller 5
The contact pressure between 0 and the driven roller 50 'with respect to the drive roller 25 is smaller in the driven roller 50' than in the driven roller 50. Since the driven roller 50 ′ is arranged on the side of the driving roller, the component force of pressing against the driving roller is the driven roller 5 ′.
This is because it is smaller than 0. 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, a belt 52 is wrapped around two driven rollers 50, 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, when a few stitches (about 10 stitches) are sewn in the absence of a sewn product, the latch electromagnet 60 of the driven roller driving means is actuated to move the lever 28 against the spring 30 as shown by the arrow in FIG. It drives upwards and therefore the driven rollers 26a, 26b (or 50, 50 ') move away 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 object is detected by the cloth detecting means 61 (see FIG. 11). This cloth detecting means is, for example, in the illustrated embodiment, the head end portion 6 near the needle 62.
3 and an optical sensor assembly composed of a light-emitting body and a light-receiving body, and a needle plate on which a sewn product is placed or a reflecting plate attached to a table. Incidentally, reference numeral 6
4 shows 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 in this embodiment comprises a thread thickness detecting means for detecting the thickness of the thread, for example, a potentiometer 70 (see FIG. 13) and a spring force adjusting means 71 for changing the pressure of the spring 30 of the driven roller driving means. There is. 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. To put it simply, the thickness of the thread is detected by the potentiometer, and the motor is rotated by the control means in response to the detection of the thread thickness, and the strength of the spring is changed via the eccentric cam and the link. Details will be described later. Figure 1
5 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. Figure 1
As is clear from FIG. 5, the number of rotations of the motor for driving the drive roller 25 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 a needle swings. This needle thread feeder is needle bar amplitude detecting means 8 for detecting the swing width of the swinging needle bar 80.
1 is provided. 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 denotes a sewing machine rotation signal generating circuit, and 10
Reference numeral 2 denotes a stop switch connected to the sewing machine rotation signal generating 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 "L" when the thread trimming solenoid is ON,
A short pulse is output when the signal is "H" when it is OFF, and when it is ON → OFF, it is "H" and when it is OFF → ON, it is "L". The timer 104 is the sewing machine rotation signal generation circuit 1
01, 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, and generates the signal "L" during the upper position detection and the lower position detection, respectively. Count control circuit 107
Counts the upper position, the lower position or the number of stitches of the sewing machine when the cloth detecting means 61 is "L" (when there is no sewing material),
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 outputs a lower position signal "H".
Disable with and enable with "L". Reference numeral 109 is a latch electromagnet position detecting means, which is a latch electromagnet 60.
Output signal "L" when the drive roller moves up, that is, when the driven roller is moved away from the drive roller, and outputs "H" when the drive roller moves down, that is, when the driven roller is pressed by the drive roller. A rising actuation circuit 110 and a descending actuation circuit 111 are connected to the latch electromagnet 60. 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 ascending operation circuit 110 is activated by the timer 104, the ON-OFF signal of the thread trimming signal generating circuit 103, the stop switch 102, or the "L"-"H" signal of the count control circuit 107. Raise. 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 is, as described above, driven rollers 26a, 26b (50, 50 ') at the time of rising.
To lower the driven roller when descending. The reset signal generation circuit 112 generates a reset signal when the power is turned on and 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. The feeding setting means 114 and the feeding detection means 115 are provided, the latch circuits 116 and 117 are connected to the feeding setting means 114, and the counter circuit 118 is connected to the feeding detection means 115.
The feeding setting means 114 keeps the driven rollers 26a, 2 during sewing.
6b, the amount of two upper yarns to be fed out and the amount of two upper yarns to be fed at the time of thread cutting are set. Feeding detection 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 1
Reference numeral 17 latches the yarn feeding amount setting at the time of thread cutting by the OFF → ON signal of the thread cutting signal generating circuit 103 and the thread cutting solenoid. The counter circuit 118 is the feeding detection means 11.
The digital pulse generated in 5 is counted and output.
The count is cleared at a specified angle which is the rotation angle of the position detecting means 106. Pitch detecting means 119 is provided, and this pitch detecting means detects the pitch of the sewing machine and outputs it as a digital signal. An error calculation circuit 120 is connected to the pitch detecting means. Further, this error calculation circuit is connected to the latch circuit 116. The above-mentioned needle bar amplitude detecting means 81 is connected to this arithmetic circuit 120.
The error calculating circuit 120 detects the detection signal from the sewing machine speed detecting means 113, the latched setting signal of the latch circuit 116,
The feed amount is calculated and output based on the pitch detection output of the pitch detection means 119 and the output of the needle bar amplitude detection means 81. A selection circuit 121 is connected to the error calculation circuit 120 and the latch circuits 116 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". Comparators 122 and 123 are connected to the selection circuit 121.
Reference numerals 2 and 123 are connected to the counter circuit 118. The comparator 122 outputs the output of the counter circuit 118 and the selection circuit 12.
1 and R side output is compared, and when they are the same, signal "L"
Is output. The comparator 123 compares the output of the counter circuit 118 with the L-side output of the selection circuit 121, and outputs a signal “L” when they are the same. Reference numeral 126 indicates 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 gripping means, and the first L electromagnet corresponds to the electromagnet of the other thread gripping means. The first R electromagnet 126 has an operating circuit 124.
Is connected, and the 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 12
4 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,
Turns off when "L" is input. Further, it is turned on when the reset signal is input. The first R electromagnet 126 controls, for example, the yarn delivery of the right needle of the two needles, and the first L electromagnet 127 controls the yarn 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 detecting means 106, and the position detecting means 1
06, the set rotation angle signal, the thread cutting signal from the thread cutting signal generating circuit 103, and the latch electromagnet position detecting means 1
The output "L" is generated by either of the signal from 09 and the signal from the stop switch 102. Operating circuit 12
9 turns on the second electromagnet 130 by inputting “H”,
This is turned 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. Further, the operating circuit 134 is connected to the one-needle setting switch 131 and the linear motor position detecting means 133,
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 does not turn ON at the same time but becomes a stop input when the switch input is “L”. Thread breakage detection means 13
In No. 2, a thread break is detected and the output is set to "L". Normally, when there is no thread break, 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. First R electromagnet 1 of the first thread gripping means
26 and a first electromagnet control circuit 136 for controlling the first L electromagnet 127. This first electromagnet control circuit outputs a signal from the stop switch 102, a signal from the latch electromagnet position detecting means 109, a rotation angle signal from the position detecting means 106, and an OFF → O signal from the thread trimming signal generating circuit 103.
"L" is output by either of the N signals. Further, it receives "L" signals from the comparators 122 and 123 and outputs "H". A frequency generation circuit 137 is connected to the thread trimming signal generation circuit 103, the stop switch 102, and the feeding setting means 114. Further, a DC motor rotation speed detecting means 138 is installed, and the DC motor rotation speed detecting means is provided with a comparator 139.
Is connected to this comparator, and a motor control drive circuit 1 is connected to this comparator.
40 is connected, and DC is connected to this motor control drive circuit.
The motor 141 is connected. 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 outputs the rotation speed of the DC motor 141 as a frequency of a 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. The 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, and the presser foot is lowered, that is, the sewing material is "H" is output when it is in the pressing state. The selection signal 121 is connected to the squeeze signal generation circuit 143. The squeeze signal generation circuit generates an "L" or "H" signal and performs the squeeze operation at "L". The thread feeding means 22 is used so that normal sewing is performed at "H".
To control. 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 limiting circuit 148 is provided, and this circuit functions to limit the yarn supply of the stop needle by inputting the one-needle setting switch 131. Referring to FIG. 16 again, a case will be described in which the feeding amount of the upper thread is controlled according to the swing width of the needle. The feeding-out setting unit 114 controls the yarn feeding-out unit 22 to set the yarn feeding-out amount. This feeding setting means 114
Is connected to a correction means 150, the correction means is connected to a comparator 151, and the comparator is connected to a pitch amount setting means 152 and a needle thread supply setting switch 153. 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 setting means 1 is provided in the feeding setting means 114.
By connecting the DC motor 141 via the motor drive control means 161 and the motor drive control means 161, the rotation of the drive roller 25 can be changed stepwise according to the needle feed pitch. The circuit for holding the upper thread by turning on the electromagnets of the first and second thread gripping means when the power of the sewing machine is turned on or off is the operation circuit 1 in the control means shown in FIG.
24, 125, first R electromagnet 126, first L electromagnet 12
7, an operating 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. These circuits have the practical advantage that no extra needle 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 clothes collar 150 with two needles, the longer the sewing line l ₁ of the other needle _(outer) than sewing line l ₁ of the one needle _(inside). Therefore, in this case, the sewing line l ₂ needs to feed the upper thread more than the sewing line l ₁ . In the needle thread supply device of the present invention, the driven roller that sends the needle thread to the sewing line l ₁ can be separated from the drive roller for a certain period of time to reduce the amount of thread delivery compared to the sewing line l ₂ . This is done by controlling the latch electromagnet that drives this driven roller. Also, the sewing line l ₁
The first thread gripping means related to the sewing line l ₂ is sewn to advance the thread gripping timing earlier than the first thread gripping means related to the sewing line l ₂ or to continue gripping for a long time to sew the thread feeding amount of the sewing line l _1. It can be less than the line l 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 action of the false stitch will be described again. The shirring signal generation circuit 143 controls the yarn delivering means 22 and the delivery setting means 11
4 and the first electromagnet control circuit 136 are 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 becomes small, the thread pulls the sewing product,
The sewn product is squeezed. In this way, the false stitch can be performed.

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.

[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 driving roller, a driven roller which is arranged so as to come into contact with or separate from the driving roller and which grips a yarn between the driving roller and feeds the yarn, and drives the driven roller. A spring for urging the driven roller to come into contact with the roller, a spring force adjusting means for adjusting the spring force of the spring, a thread thickness detecting means for detecting the thickness of the thread, and a control means. The control means controls the spring force adjusting means so that the spring force adjusting means appropriately sets the spring force of the driven roller in accordance with the thickness of the thread detected by the thread thickness detecting means. Upper thread feeder.