JPH0358758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a setting device 24 that is capable of generating a setting signal corresponding to the length of needle thread required to form one stitch in accordance with different sewing conditions, and a setting device 24 that is arranged in relation to the main shaft. A position detection device 17 that detects a specific rotation angle of the main shaft corresponding to a specific time other than the needle thread tensioning time by the balance and generates a position signal; A sewing machine is provided with feeding devices 6, 7, and 12 that operate to feed from a supply source, and is configured to feed out needle thread of the length required for forming one stitch from the supply source in advance every time one stitch is formed. Regarding the needle thread supply device, in particular, the difference between the needle thread length corresponding to a setting signal and the needle thread length actually fed out from the supply source is calculated, and the value is subtracted from the needle thread length of the next setting signal to correct it. It is characterized by

Conventionally, for example, two holding means that can hold and release the needle thread by electromagnetic action related to energization and de-energization, and a feeding body that is placed on the needle thread path between the two holding means and operates in synchronization with the thread take-up. Therefore, the holding means on the supply source side releases the needle thread at a time other than when the needle thread is tensioned by the thread take-up, and the needle thread path increases with the holding means on the thread take-up side holding the needle thread. is fed from the supply source between both holding means, and as a predetermined length of needle thread is fed in, the holding means on the supply source side pinches the needle thread to prevent subsequent feeding. In a type of feeding device in which the other holding means is used to release the needle thread, the retracted needle thread is pulled out from both holding means as the thread take-up next ascends, the holding means on the supply source side is used. There is a mechanical delay between when the current is applied to the motor and when it actually takes effect, and during that time, the needle thread is paid out excessively, making it impossible to accurately control the amount of needle thread delivery, and, for example, when using a stepping motor. In a type of feeding device in which the needle thread can be fed out by the rotation of a roller that is linked to the stepping motor, and the rotation of the stepping motor is controlled by the above-mentioned setting signal, slippage occurs between the roller and the needle thread. In this case, similar to the above, there was a drawback that the feeding amount could not be accurately controlled.

This invention is based on the value of the actual needle thread length,
It is an object of the present invention to eliminate the above-mentioned drawbacks of the conventional method by subtracting the difference between the needle thread length value based on the setting signal and the needle thread length value based on the setting signal for the next stitch.

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

About the configuration of the mechanical part The sewing machine 1 has a main shaft (not shown) that rotates in conjunction with a drive source, a needle bar 3 that fixes a needle 2 with a needle thread T at its lower end and moves up and down in conjunction with the main shaft, and a needle. A known device comprising a thread take-up 5 which supports the needle thread T between the thread supply source and the needle 2 and moves back and forth between two positions in conjunction with the main shaft to tension and relax the needle thread T. The relationship between the needle bar 3 and the thread take-up lever 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.
In addition to increasing the needle thread path between needle 2 and thread take-up 7, the needle thread take-up 5 is connected to
relate to the movement of

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.

About the electric circuit In FIG. 2, the feeding detection device 16 generates one pulse every time the rotating body 15 rotates by a certain angle. The first position detection device 17 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) is output, and when the needle 2 is located below the bed surface, a low level signal (hereinafter referred to as L) is output. The second position detection device 18 is disposed in relation to the main shaft or a part linked thereto, detects the rotation angle of the main shaft corresponding to the tensioning period of the needle thread T by the thread take-up 5, and outputs an H signal. The counter 19 is reset at the fall of the signal of the timer _MS1 , which is activated by the fall of the signal of the first position detection device 17, and counts the pulses from the assembly detection device 16.

The third position detection device 30 detects when the needle 2 pierces the bed plane and the feed dog sinks below the bed plane immediately before the needle 2 comes out of the sewing machine bed plane after the assembly body 12 has finished forward movement in the thread payout direction. Later, a specific rotation angle of the main shaft is detected before the needle thread feeding operation of the feeding body 12 starts, and an H signal is generated.
Flip-flop FF ₁ is reset by turning off the start switch (not shown) of sewing machine 1,
By turning on, the reset is canceled and the Q output is inverted from L to H in relation to the rise of the output of the third position detection device 30. Multiplexer 20 is FF ₁
When receiving the L signal from FF 1, the input signal from the first setting device 21 is output, and when receiving the H signal from FF ₁ , the input signal from the holding circuit 22 is output. The holding circuit 22 captures the falling edge of the output of the timer MS ₂ and simultaneously receives the input signal from the subtractor 23 and outputs the signal. The subtraction device 23 calculates the value e of the output signal of the second setting device 24 from the holding circuit 2, which will be described later.
The value f obtained by subtracting the value c of the output signal of No. 5 is output.
The first setting device 21 and the second setting device 24 are for setting the length of the needle thread T to be fed out in accordance with the length of the needle thread T required for one stitch type. A digital code corresponding to the average ideal needle thread payout length is generated for each selected sewing pattern, and the second setting device 24 sets the needle thread T every time one stitch is formed, as will be described later with reference to FIG. A digital code is generated according to the length. This digital code is associated with the number of pulses from the payout detection device 16 corresponding to the rotation angle of the rotating body 15 which is proportional to the payout amount.

The subtraction device 26 calculates the value a of the output signal of the counter 19.
The value c obtained by subtracting the value b of the output signal of the multiplexer 20 from the multiplexer 20 is output. The holding circuit 25 detects the rising edge of the signal from the third position detecting device 30 and outputs the subtracted value c at the same time.

The comparison circuit 27 compares the output values of the counter 19 and the multiplexer 20, and when both match, the output value is H.
generates a match signal. FF ₂ is reset by the fall of the signal of timer MS ₁ , sets the Q terminal output at that time to L, and inverts the Q terminal output from L to H by the match signal from the comparison circuit 26.

The operating circuits 28 and 29 open when receiving the H signal from FF ₂ to excite the corresponding first solenoid 8 and second solenoid 9, and close when receiving the L signal to demagnetize them. It should be noted that the operating circuit 28, when it is open, detects the second position detecting device 13.
When receiving a power down signal of H from (when an L signal is generated in the second position detection device 18),
A smaller current is supplied to the first solenoid 8 than when the signal is received. That is, an example of the configuration of the operating circuit 23 can be expressed as an analog circuit as shown in FIG. Here, P is a known operational amplifier having a comparison function, and Tr ₁ , Tr ₂ , and Tr ₃ are transistors. When the Q terminal output of FF ₂ is L, transistor Tr 2 is turned on, and the transistor Tr ₂ is turned on.
Since Tr ₁ is turned off, the first solenoid 8 is demagnetized,
When the Q terminal output of FF ₂ is H, the transistor Tr ₂
Since the transistor Tr ₁ is turned off, the transistor Tr 1 is turned on, and the first solenoid 8 is thereby excited. Furthermore, when transistor Tr ₃ turns on in response to an H power-down signal while transistor Tr ₂ is off, the reference voltage of operational amplifier P becomes lower, so the current value supplied to first solenoid 8 decreases. On the other hand, when the transistor Tr ₃ receives the L signal and turns off, the reference voltage of the operational amplifier P increases, so that the current value supplied to the first solenoid 8 increases.

When the sewing machine is stopped, FF ₃ receives an H signal at the R terminal and sets the Q terminal output to L, and when the sewing machine starts, it receives an L signal at the R terminal and releases the reset, and the AND gate circuit G When receiving an H signal from the terminal, the Q terminal output is set to H. The alarm device 45 is a buzzer, a lamp, etc., and when the Q terminal output of FF ₃ becomes H, the alarm device 45 is activated for a certain period of time via a timer TM.
Generates sounds, lights, displays, etc.

Details of the second setting device 24 in FIG.
As shown in the figure. Here, the amplitude signal Y regarding the amplitude of the needle bar 3 and the feed amount signal X regarding the cloth feed pitch are signals read from a storage device (not shown) such as ROM or RAM, and the detection of these signals The timing is detected in relation to the fall of the output of the third position detection device 30, as shown in FIG.

These signals X and Y are processed by squarers 31 and 32, respectively, and then added by an adder 33.Then, the next multiplier 34 inputs the feed amount (stitch pitch) coefficient setting switch 35. After being multiplied by the output m, it is processed by the k ₁ ' multiplier 36 and the square root operator 37 arranged in parallel, and the output of the square root operator 37 is sent to the adder 3 through the k ₂ ' multiplier 38.
9, the output of the k ₁ ' multiplier 36 is sent as is to the adder 39, and these added data are sent to the adder 40. The feed rate coefficient setting switch 35 has a code of several bits, and can output a digital code corresponding to the operation mode by manual operation.

The material thickness signal D corresponding to the raised position of the presser foot (not shown) from the top surface of the bed is detected at the same timing as the feed amount signal X and the swing width signal Y, and is also counter 42
After being multiplied by the output k ₃ of , the adder 40 adds the output data of the adder 39 , and the output is further processed through the k ₄ adder 43 .

Therefore, the output of the k ₄ adder 43, that is, the planned payout amount l of the needle thread T, is k ₁ ′m=k ₁ , k ₂ ′√=k ₂ , X ²
If +Y ² = P, then l=k ₁ P ² +k ₂ P+k ₃ D+k ₄ and P
It is expressed as a quadratic equation. Feeding detection amount calculator 44
converts the output of the _k4 adder 43 into the number of pulses generated by the feed-out detection device 16 corresponding to the rotation angle of the rotating body 15 which is proportional to the planned pay-out length of the needle thread T, and thereby determines the planned pay-out length of the needle thread T. generates a digital code corresponding to the

The coefficient counter 42 is connected to the up/down switch 4 as shown in the flowchart of FIG.
In connection with the operations of 5 and 46, the output value _k3 can be changed stepwise within a predetermined range centered on the initial value "1", and is reset by receiving an H signal at the R terminal, As a result, the output becomes the initial value "1", and the number corresponding to the output value _k3 of the counter 42 is displayed on a display window (not shown) provided on the front of the sewing machine frame. It is becoming more and more like this. The pattern switching signal E is related to the stitch pattern selection operation, and the power-on signal F is an H signal that is generated for a certain period of time in connection with power-on.

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

First, when a sewing pattern is selected by the pattern selection means, the first setting means 21 outputs a signal d corresponding to a unique needle thread payout length corresponding to the selected pattern. Next, when the sewing machine is started, the reset of FF ₁ is canceled, but the Q terminal output remains at L, and the output d of the first setting means 21 is sent to the comparison circuit 27 and the subtraction device 26 via the multiplexer 20.

On the other hand, when the sewing machine 1 moves and the thread take-up 5 descends from the top dead center and the needle thread T closer to the needle than the holding means 7 begins to loosen, the counter 19 is reset in relation to the fall of the signal of the timer _MS1 . Along with FF ₂
is cleared, the operating circuit 28 closes and the first solenoid 8 is demagnetized, releasing the needle thread T from holding by the holding means 6. At the same time, the operating circuit 29 is opened to excite the second solenoid 9, and the holding means 7 demagnetizes the needle thread T. Needle thread T
to hold it in an impassable manner.

Immediately after this, the feeding body 12 moves counterclockwise around the shaft 14 from the state shown in FIG. Therefore, the needle thread T having a length corresponding to the increased path is let out from the bobbin 4.

When the needle thread T is paid out by the above action, the rotating body 15 is rotated clockwise in FIG. 1, and a number of pulses proportional to the rotation angle are generated from the feeding detection device 16. These pulses are counted by a counter 19, and the counted value is sent to a comparison circuit 27 and a subtraction device 26. Therefore, when the count value of the counter 19 matches the value d of the output of the first setting device 21, the comparison circuit 27 outputs a matching signal of H.
Since FF ₂ is set and the Q terminal output is reversed from L to H, the first solenoid 8 is energized and the holding means 6
The second solenoid 9 holds the needle thread T so that it cannot pass through and prevents the needle thread T from being fed out thereafter.
is demagnetized and the holding means 7 releases the needle thread T so that it can pass therethrough.

Note that even if a matching signal is generated from the comparison circuit 27 before the forward movement of the feeding body 12 is finished, and the needle thread T is clamped by the holding means 6 so that it cannot pass through, the holding means 7 simultaneously As well as releasing the grip,
At this time, the thread take-up 5 loosens the needle thread T closer to the needle 2 than the holding means 7, so even if the feeding body 12 moves further forward thereafter, the loose needle thread T closer to the needle 2 than the holding means 7 Passing through the holding means 7, both holding means 6,
7, the needle thread T is not strongly tensioned or drawn out from the bobbin 5.

Next, when the thread take-up 5 starts to rise from the bottom dead center, the needle thread T between the needle 2 and the holding means 6 is gradually pulled up and the stitch is knotted. Also, while forming the first stitch, the cloth thickness signal D, the feed amount signal X and the amplitude signal Y related to the next stitch are detected, and are consumed when forming the next stitch. The length of the needle thread T is calculated, and its value e is output from the second setting device 24. When the signal from the third position detection device 30 rises, FF ₁ is set and its Q terminal output is inverted to H, so that the signal from the second setting device 24 becomes FF _1.
After a certain period of time has passed since the timer MS 2 is set, that is, in relation to the fall of the timer MS ₂ output, the multiplexer 2
0 to the comparison circuit 27.

Therefore, for the first stitch, the needle thread payout amount is determined by the signal from the first setting device 21, but from the second stitch onward, it is calculated by combining the feed pitch, needle swing width, and fabric thickness for forming the next stitch. The needle thread payout amount is determined by the signal from the second setting device 24. When the output value of the counter 19 and the output value of the multiplexer 20 match, a match signal is generated from the comparison circuit 27, and the same operation as described above is repeated to obtain the required length for each stitch formation. The needle thread T is previously fed out from the bobbin 4 between the holding means 6 and 7.

The above operation is performed when the needle thread T having the length corresponding to the signals from the first setting device 21 and the second setting device 24 is sewn out accurately every time a stitch is formed. Counter 19 starts after
The needle thread T is held by the holding means 6 until it is reset.
When the needle thread is fed out from the front to the front in the needle thread supply direction, the amount of excess feed is calculated by the subtraction device 26, and the value c is sent from the holding circuit 25 at the next rise of the signal from the position detection device 17. Output. As a result, the value f obtained by subtracting the output value c of the subtraction device 26 from the output value e of the second setting device 24 by the subtraction device 23 is inputted to one input section of the comparison circuit 27 via the multiplexer 20. When the count value of the counter 19 matches this value, a match signal is generated from the comparison circuit 27, and the same operation as described above is repeated.

That is, the length of the needle thread T set by the first setting device 21 or the second setting device 24 when forming one stitch, and the length of the needle thread T actually fed between the holding means 6 and 7 by the feeding body 12. If the lengths of the needle thread T do not match, the needle thread payout length is corrected by the difference between the two when forming the next stitch.

Next, during the excitation of the first solenoid 8 described above, when the output of the second position detection device 18 is L, the transistor Tr ₃ is turned on, and the reference voltage of the operational amplifier P is relatively lower than that in the case described later. The excitation current becomes smaller. In this state, the action of the feeding body 12 applies a force to the holding means 6 to clamp the needle thread T to such an extent that the needle thread T is not drawn into both the holding means 6 and 7, and the second position detection device When the output of 18 is H, the transistor Tr ₃ is turned off and the reference voltage of the operational amplifier P becomes higher than in the above case, and the excitation current of the first solenoid 8 increases. A force is given to the holding means 6 to hold the needle thread T to such an extent that the needle thread T is not drawn in between the holding means 6 and 7 even if the thread T is strongly tensioned.

The output of the k ₄ adder 43, which is the basis for calculating the value e of the output of the second setting device 24, is ``l=k <sub>1</sub> P <sup>2</sup> + k <sub>2</sub> P+
k <sub>3</sub> D + k <sub>4</sub> '', so if the feed amount coefficient setting switch 35 is operated and the output value m is changed appropriately, the coefficients ``k ₁ '' and ``k <sub>2</sub> '' of ``P ² '' will change.
The output "l" of the _k4 adder 43 changes, which causes the output of the second setting device 24, which is input to one input of the comparison circuit 27, to change. Note that the adjustment by the feed amount coefficient setting switch 35 is performed when the input signal to the stepping motor for feeding or needle swing is input into the calculation formula for needle thread payout, and the adjustment by the feed rate coefficient setting switch 35 is based on the feed pitch input into the calculation formula and the actual feed pitch. This is done for each sewing machine when the feed pitches do not match.

When the up switch 45 is operated, the coefficient “k ₃ ” of the cloth thickness signal “D” is output from the k ₄ adder 43.
The value of ``k'' increases stepwise within a preset range centered on the initial value ``1'', and when the down switch 46 is operated, the value of the coefficient `` _k3 '' decreases stepwise. Although the output of the second setting device 24 changes, the coefficient counter 42 is reset in connection with pattern selection and power-on, and the value of the coefficient "k ₃ " returns to the initial value "1". This adjustment should be made at the appropriate time when the thread tension balance of the upper and lower threads is intentionally changed in order to give gears or irregularities to the fabric during sewing, or to make the seams hang upward or downward.

Next, if the needle thread T is not passed between both holding plates 10 of the holding means 6, the tension of the needle thread T by the thread take-up lever 5 will cause the needle thread T to be moved to the bobbin winder even outside the period when the needle thread is being fed out by the feeding body 12. However, when the sewing machine is rotating, FF ₃ is reset and the thread take-up lever 5 is released.
During the needle thread tension period, the output of the first position detection device 17 is H and the gate G is opened.
_FF3 is set by the pulse generated in the timer TM.
The alarm device 30 is activated for a certain period of time via.

As described above, the present invention provides a feed-out detection device 16 that is displaced in proportion to the length of needle thread fed out by the feed-out device and generates a yarn amount signal corresponding to the displacement value.
and a first subtraction circuit 25 that outputs a value obtained by subtracting the value of the setting signal from the yarn amount signal after the operation of the feeding device.
26, and a second subtraction circuit 20 which outputs the value obtained by subtracting the output value of the first subtraction device from the setting signal to the feeding device and the first subtraction circuit as the next setting signal until the next position signal is generated. , 22, 23, even if there is a delay in the mechanical operation of the solenoid for restricting feeding or slippage between the feeding circuit roller and the needle thread, this is corrected when forming the next stitch. , the amount of needle thread fed out can be accurately controlled, which results in uniform thread tightness of the stitches and improved sewing quality.

In this embodiment, the rod-shaped feeding body 12 is the cam body 13.
The figure shows one that moves back and forth in conjunction with the
As in the first embodiment of No.-82712, a feeding body having an outer peripheral cam surface facing the needle thread path may be rotated.

In this embodiment, the two holding means are controlled based on the setting signal, but one of the disks around which the needle thread is wound around the outer circumference or the rollers arranged facing each other across the needle thread is controlled based on the setting signal. It may also be rotated via a base stepping motor.

In this embodiment, a first setting device 21 and a second setting device 24 are provided, and the first setting device 21 generates a digital code corresponding to the average ideal needle thread delivery length that varies for each sewing pattern. However,
The same digital code may be generated for all patterns.

In this example, the appropriate needle thread payout length l is defined as l=
Although the value obtained from the equation k ₁ P ² +k ₂ P+k ₃ D+k ₄ is shown, it may be obtained using the equation 1=k ₂ P+k ₃ D.

[Brief explanation of drawings]

Figure 1 is a perspective view of the main parts, Figure 2 is a block diagram of the electric circuit, and Figure 3 is the operating circuit 28 in Figure 2.
4 is a block diagram showing details of the second setting device 24 in FIG. 2, FIG. 5 is a time chart, and FIG. 6 is a flow chart showing the relationship between the up/down switch and the coefficient counter. It's a chat.

Claims (1)

[Claims] 1 Setting devices 21 and 24 capable of generating setting signals corresponding to the length of needle thread required to form one stitch in response to different sewing conditions; A payout detection device 16 that is displaced in proportion to the payout length and generates a yarn amount signal corresponding to the amount of displacement, and a comparison circuit 27 that compares the setting signal and the yarn amount signal and generates a match signal when they match. a detection device 17 arranged in relation to the main spindle and configured to detect a specific rotation angle of the main spindle corresponding to a specific time other than the needle thread tensioning period by the thread take-up and generate a position signal; The system is equipped with feeding devices 6, 7, and 12 that operate until a matching signal is generated to feed out a length of needle thread from a supply source, and the needle thread of the length required for one stitch is fed out every time one stitch is formed. In a needle thread supply device that is arranged to feed out the thread from a supply source in advance, a first subtraction circuit 25, 2 outputs a value obtained by subtracting the value of the setting signal from the thread amount signal after the operation of the feeding device.
6, and a second subtraction circuit 20 that subtracts the value of the output of the first subtraction device from the setting signal until the next position signal is generated and outputs the value obtained by subtracting the value of the output from the first subtraction device as the next setting signal to the comparison circuit and the first subtraction circuit. , 22, 23 are provided so that the difference between the needle thread length corresponding to the setting signal and the needle thread length actually paid out from the supply source is corrected at the next feeding. Device.