JPH0345678B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an automatic stop device for automatically stopping a sewing machine by detecting the end of a workpiece.

[Prior art]

Various devices have already been proposed that detect the end of the material to be sewn and automatically stop the sewing machine, but conventional automatic stop devices are configured to stop the sewing machine with a cloth out signal, so it is difficult to run the sewing machine idly. In order to solve this problem, it is necessary to provide a separate means for connecting and separating the cloth detection device, or to place the cloth detection device in front of the sewing machine seam in the cloth feeding direction. . However, even with these methods, the circuit configuration becomes complicated, and it is troublesome to operate the contact/separate means every time the sewing machine is used to sew.
In addition, in the latter case, the end of the fabric is detected before the sewing is finished, so in order to stop the sewing machine after sewing to the end of the fabric, a timer or counter must be installed that operates in conjunction with the above detection. First, like the former, it had the disadvantage of complicating the circuit configuration.

〔the purpose〕

The present application was made in view of the above-mentioned drawbacks, and the sewing machine stop circuit is activated to stop the sewing machine only when the detection state changes from the detection state of cloth present to the detection state of no cloth, that is, there is no material to be sewn from the beginning. An object of the present invention is to provide an automatic stop device that can operate a sewing machine in some cases. Still another object is to provide an automatic stop device that uses a cloth thickness detection device in combination with a cloth edge detection device.

〔composition〕

In order to achieve the above object, the present invention provides a cloth detection device that generates a cloth presence signal and a cloth absence signal by engaging and disengaging with a workpiece, particularly in a sewing section of a sewing machine, and a cloth detection device that generates a cloth presence signal and a cloth absence signal, and a starter device for starting a sewing machine motor. A start switch that generates a signal, a motor stop circuit that stops the sewing machine motor by its action, and the outputs of the fabric detection device and the start switch are input, and when the start signal is input, it is inactive regardless of the output state of the fabric detection device, The present invention is characterized by having a control circuit that operates as a motor stop circuit by changing the output of the cloth detecting device from a cloth present signal to a cloth absent signal after inputting a start signal.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the sewing machine 1 includes a main shaft (not shown) that rotates in conjunction with a drive source, and a needle bar that fixes a needle 2 having a needle thread T at its lower end and moves up and down in conjunction with the main shaft. 3, and a thread take-up 5 that reciprocates between two positions in conjunction with the main shaft to support the needle thread T between the bobbin 4 as a needle thread supply source and the needle 2, and to tension and relax the needle thread T. The relationship between the needle bar 3 and the balance 5 with respect to the rotation angle of the main shaft is as shown in FIG.

The first holding means 6 and the second holding means 7 are connected to the balance 5
On the needle thread path between the thread spool 4 and the thread take-up 4, they are arranged at a distance from each other at the front and the front in the needle thread supply direction from the thread spool 4 to the thread take-up lever 5, and each has an electromagnet (first solenoid) 8 and an electromagnet (second solenoid). ) 9, and a pair of holding plates 10 and 11 which immovably clamp the needle thread T when energized and movably release the needle thread T when de-energized.

The feeding body 12 is capable of constant rocking around a shaft 14 in conjunction with an eccentric cam 13 that rotates in conjunction with the main shaft, and its free end is arranged in relation to the needle thread path between the two holding means 6 and 7. , when the needle 2 is located below the bed surface as shown in FIG.
The movement of the needle 2 and the thread take-up 5 is related to the movement of the needle 2 and the thread take-up 5 so as to increase the needle thread path between the needle thread take-up 7 and to minimize the length of time until the needle thread take-up is tensioned by the thread take-up 5.

Further, the rotating body 15 is arranged between the holding means 6 and 7 so as to be rotatable in proportion to the distance traveled by the needle thread T when it moves along its path.

The cloth thickness detection device 62 detects the presence or absence of cloth at the sewing machine seam portion and the thickness of the cloth.
It is arranged in relation to 1. The presser bar 21 is of a known type, has a cloth presser 17 at its lower end, and is always subject to the downward force of an elastic body (not shown). Further, the cloth thickness detection device 62 includes a volume 25 that generates an analog signal as a cloth thickness signal corresponding to the rotational position of the shaft 24, and a swinging body 26 fixed to the shaft 24. The rocking body 26 is always acted in a clockwise direction by a coil spring 27 installed between it and the machine frame, and one end 26a of the rocking body 26 is connected to the presser bar 2.
1 is engaged with the upper surface of the actuating body 22 fixed to 1.

In FIG. 2, the feeding detection device 16 generates one pulse each time the rotating body 15 rotates by a certain angle. The position detection device 61 is arranged in relation to the main shaft or a part linked thereto, and detects a specific rotation angle of the main shaft corresponding to the time when the needle 2 is located above the bed surface, and detects a relatively high level (hereinafter referred to as H)
A low level signal (hereinafter referred to as L) is output when the needle 2 is located below the bed surface.

The presser foot lift switch 63 outputs an H signal in connection with lifting the presser foot 17 to a predetermined position to release the workpiece by rotating the operating lever 44 counterclockwise from the state shown in FIG. Occur.

The memory circuit 66 stores information regarding the swing width of the needle 2 for each stitch (stitch width signal Y) and information about the horizontal movement amount of the cloth feed dog (not shown) (feed amount signal X).
The stored information corresponding to the next stitch is read out via the pattern control circuit 67 when the output of the position detection device 61 rises, and these pieces of information are input to the amplitude signal Y, At the same time that the feed amount signal X is sent to the latch circuit 68, the amplitude signal Y is also sent to the latch circuit 69, and the feed amount signal X is also sent to the latch circuit 70. Note that the latch circuit 69 is operated via the mono multivibrator (one shot) MS ₁ and the inverter I ₁ in relation to the rise of the output of the position detection device 61, and the latch circuit 68,
70 operates in relation to the fall of the position signal;
Furthermore, each latch circuit outputs its input as is by operation.

A needle swing stepping motor (ST.M) 71 is used to operate the needle bar swing mechanism, and is driven via a drive circuit 72 in response to the output of the latch circuit 69. Feed stepping motor (ST.M) 73
is for operating the feed mechanism, and is driven by receiving the output of the latch circuit 70 via the drive circuit 74.

The setting device 75 sets the amount of needle thread required for each stitch formation based on the signals X, Y, and D inputted through the latch circuit 68 and the latch circuit 76 operated in the same manner. For example _{, the} sum of the square value of ^the feed amount signal The value A obtained by adding the value of D to the power of the constant K ₂ as "K ₁ P + K ₂ D"
is now output.

Comparison circuit 78 generates an H signal when the output values of setting device 75 and counter 79 match.
The counter 79 outputs a value obtained by counting the output pulses of the feeding detection device 16, and is reset by the fall of the position signal.

Flip-flop _FF1 becomes active upon receiving the H signal from comparator circuit 78, and is reset to non-operational state in relation to the fall of the position signal, and its output is passed through AND gate _G1 and inverter _I2 . Sent to ANDGATE G ₂ . Electromagnet 8,9
are excited by the H output of the AND gates G ₁ and G ₂ via the corresponding operating circuits 80 and 81, respectively, and the L
Demagnetizes by output.

The presser foot lifting switch 63 is used to release the needle thread T from both holding means 6 and 7 in the upper stop zone where the needle 2 has come out of the bed surface in connection with raising the presser foot. The output is input to AND gates G ₁ and G ₂ via AND gate G ₄ and inverter I ₃ .

The comparison circuit 84 receives the cloth thickness signal output from the latch circuit 76 and a signal of a set value 83 for outputting a certain signal. The set value 83 always outputs a signal corresponding to the cloth thickness "0". Therefore, when the cloth thickness is "0", that is, when there is no cloth, the signals of the latch circuit 76 and the set value 83 match, and the comparison circuit 84 outputs an H signal. The flip-flop _FF2 is reset at the rising edge of the one-shot _MS2 by the output of the sewing machine start signal which is outputted in connection with the start of the sewing machine, and receives the no-cloth signal H from the comparator circuit 84 via the inverter _I4 . Or the output is input to NOR gate _G5 . Flip-flop FF ₃ is activated by the rising edge of the clothless signal H of the comparison circuit 84;
It is designed to be reset at the rising edge of 1.
The Q output of FF3 is input to the counter 85, which is reset at the rising edge of the counter 85, and the rising signal of 61 is counted, and for example, an H signal is output at 3 stitches.
Input to AND gate G ₆ . The alarm device 86 is, for example, a lamp, a buzzer, a light emitting diode, etc., for warning that there is no cloth.
By output of FF ₂ or H output of AND gate G ₆
It is designed to operate with the L output from _G5 .
The motor stop circuit 87 is a circuit that receives the H signal from the AND gate _G6 and outputs a signal for stopping the sewing machine motor.

The present invention has the above configuration, and its operation will be explained next.

The electromagnets 8 and 9 of both holding means 6 and 7 are energized when all four inputs of the corresponding gates G ₁ and G ₂ become H, and demagnetized when one of them becomes L, but in normal case. gate as described below.
Since all three inputs from G ₄ and G ₅ are at H, whether to energize or de-energize is determined by the output state of flip-flop FF ₁ .

Therefore, during normal sewing, the needle bar 3, the thread take-up lever 5, and the feeding arm 12 reciprocate along the timing curve shown in FIG. The upward movement of the feeding arm 12 in _FIG . L of
It is reset by the output, the output of gate _G1 is L, the output of gate _G2 is H, and the electromagnet 8
is demagnetized, the electromagnet 9 is excited, one holding means 6 releases the needle thread T, and the other holding means 7 holds the needle thread T, so the reciprocal movement of the feeding arm 12 increases the A needle thread T corresponding to the needle thread path is fed from the bobbin spool 4 between the holding means 6 and 7. At this time, the pulley 5 rotates as the needle thread T moves, and the feed detection device 16 generates a number of clock pulses proportional to the rotation angle. This clock pulse is counted by a counter 79 and inputted to one input of a comparison circuit 78. Further, the other input section of the comparison circuit 78 is connected to the storage circuit 6.
Feed amount signal X and amplitude signal Y read from 6
The value calculated by the setting device 75 based on the cloth thickness signal D from the cloth thickness detecting device 62 is input, and the comparator circuit 78 outputs an H signal when the counted value of the counter 79 matches the theoretical value. This inverts the output of flip-flop FF ₁ from L to H, so
Electromagnet 8 is energized and electromagnet 9 is demagnetized.

Therefore, after the needle thread T of a predetermined length is fed between the two holding means 6 and 7, the first holding means 6 holds the needle thread T so that it cannot pass through and prevents it from being paid out from the bobbin spool 4. At the same time, the second holding means 7 releases the needle thread T so that it can freely pass through. Note that if the needle thread T of the predetermined length is paid out during the forward movement of the feeding arm 12, the slack needle thread T between the second holding means 7 and the needle 2 will be removed during the subsequent forward movement of the feeding arm 12. It is temporarily pulled back between both holding means 6 and 7.

Further, since the feeding arm 12 returns to its original state before the needle thread T is tensioned by the thread take-up lever 5, the first holding means 6 and the needle thread between the stitches are The T is gradually tightened, thereby tightening the seam with appropriate strength and knotting. Thereafter, the same operation is repeated every time one stitch is formed.

As mentioned above, the feed amount signal X, the amplitude signal Y,
The required amount of thread calculated based on the cloth thickness signal D is fed out every time one stitch is formed.

When the sewing machine is stopped near the lowest point of the needle bar in order to rotate the cloth around needle 2, the output of gate _G4 remains at L and does not change even if the presser foot is raised.
The state of both holding means 6 and 7 remains the same as before the sewing machine stopped, and if the sewing machine is started again, the scheduled stitches will continue to be formed, but the sewing machine will be stopped near the highest point of the needle bar in order to take out the fabric from the seam part. In this case, when the presser foot is raised, the output of gate _G4 becomes H.
As a result, the gates G ₁ and G ₂ are closed, so that the electromagnets 8 and 9 are demagnetized and both the holding means 6 and 7 release the needle thread T.

When the operator starts the sewing machine without cloth, that is, without setting cloth, one shot _MS2 is activated by the sewing machine start signal, and flip-flop _FF2 is reset. Also, since the cloth is not set, the comparison circuit 8 is activated by the signal from the latch circuit 76 when the position detection device 61 falls.
4 outputs an H signal, flip-flop, FF ₃
A high signal is input to flip-flop _FF2 , and a low signal is input to flip-flop FF2.

Since the output of the flip-flop _FF2 remains at H and the Q output remains at L, an H signal is input to the gate _G5 , and the alarm device 86 is activated. Furthermore, since the Q output L is input to the gate _G6 ,
Since the motor stop circuit 87 does not operate, the sewing machine motor continues to rotate. In other words, if the sewing machine is started without any cloth from the beginning, only the alarm device 86 will operate and the motor will rotate.

When the sewing machine is started with the cloth set from the beginning, the output from the comparator circuit 84 is always an L signal, inverter _I4 is H, and flip-flop _FF2 outputs an L signal and a Q signal of H. be done.
Or, since the input of flip-flop _FF3 is L, Q remains L, gate _G6 does not operate,
All inputs to gate _G5 are also L, and alarm device 8
6 and motor stop circuit 87 do not operate, normal sewing operation can be performed.

Initially, the cloth is set and the sewing operation is performed, and if the cloth runs out during the sewing operation, the signal of the comparator circuit 84 becomes H, and the H signal is input to the flip-flop _{FF3 .} Since the position detecting device 61 is reset every rotation of the main shaft at the rising edge, the Q output of the flip-flop _FF3 changes from L to H. Also, the counter 85 is reset by the H signal of this Q output, and its output becomes L.
When the rising edge of the position detection device 61 is counted, for example, 3 stitches, the output becomes H and is input to the gate _G6 . The counter 85 does not want to immediately stop the sewing machine when the cloth runs out, so it allows some margin. Even if the input signal of the flip-flop FF ₂ changes from H to L, Q remains at H because the reset terminal does not rise, and therefore the signal from the comparator circuit 84 becomes
When three stitches continue, the H signal is input to all gates _G6 , the motor stop circuit 87 operates, and gate _G5
When the H signal is input to the alarm device 86, the alarm device 86 also operates.

〔effect〕

As described above, the present invention activates the motor stop circuit to stop the sewing machine only when the detected state of the object to be sewn by the cloth detection device changes from "cloth present" to "no cloth". Since the sewing machine is configured so that it can be started by operating the start switch in the case of "No" detection state, it is easy to adjust the sewing machine that involves idle operation, and it is also possible to adjust the number of threads before sewing after thread breakage or thread replacement. By empty needle stitching, there are effects such as being able to reliably knot the seam from the first stitch at the beginning of sewing. Furthermore, by using the fabric thickness detection device used at the needle thread supply position as a fabric presence/absence detection device via a comparison circuit, the structure of the automatic stop device in this type of sewing machine can be simplified and the cost can be reduced.

In the above embodiment, the feed-out signal (thread amount signal)
Although the present invention is applied to a sewing machine equipped with a needle thread supply device that feeds the amount of needle thread corresponding to the amount of needle thread from a bobbin winder to a thread take-up every time a stitch is formed, the present invention is applicable to a sewing machine that is not equipped with a needle thread supply device. may be applied. Further, the needle thread supply device of the embodiment includes two holding means 6,
7, a needle thread path between these holding means, a feeding body 12 which increases and decreases in time with the vertical movement period of the needle bar, and a feeding detection device for detecting the amount of thread fed out from the bobbin. However, any feeding method may be used as long as it is equipped with a cloth thickness detection device. It may be configured such that a predetermined amount of thread is paid out from the bobbin by controlling the amount of rotation of the thread.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of a sewing machine according to the present invention;
Figure 2 is a block diagram of the electric circuit, and Figure 3 is a time chart.

Claims (1)

[Scope of Claims] 1. A cloth detection device that generates a cloth presence signal and a cloth absence signal according to engagement and disengagement with a workpiece in a sewing section of the sewing machine, and a starter device that generates a start signal for starting a sewing machine motor. The switch, a motor stop circuit that stops the sewing machine motor by its action, the output of the fabric detection device and the start switch are input, and when the start signal is input, it is inactive regardless of the output state of the fabric detection device, and after the start signal is input, An automatic stop device for a sewing machine, comprising: a control circuit that operates a motor stop circuit when the output of a cloth detection device changes from a cloth present signal to a cloth absent signal. 2. The fabric detection device includes a movable body that can be engaged with the upper surface of the workpiece in the sewing section of the sewing machine and is displaced up and down according to the thickness of the workpiece, and a fabric thickness signal that corresponds to the amount of displacement of the movable body. The generated volume and the reference signal corresponding to zero cloth thickness are input to one side, and the cloth thickness signal from the volume is input to the other input, and when both inputs match, a no cloth signal is generated, and when they do not match, a cloth presence signal is generated. An automatic stopping device for a sewing machine according to claim 1, comprising a comparison circuit. 3. A calculation circuit that calculates the amount of thread required to form one stitch from the length of the stitch to be sewn and the thickness of the material to be sewn and outputs a corresponding thread amount signal, and a feeding device that operates in response to the thread amount signal. In a sewing machine equipped with a needle thread supply device that feeds the required amount of thread from a spool to a thread take-up each time a stitch is formed, the device for detecting the thickness of the workpiece is replaced by a fabric detection device that detects the presence or absence of fabric. An automatic stop device for a sewing machine according to claim 1, characterized in that the automatic stop device is used in conjunction with the device.