JPS6192698A - Detection of yarn cutting in sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention outputs a thread breakage signal that stops the operation of the sewing machine when at least one of the upper thread and the lower thread of the sewing machine breaks. A method for detecting thread breakage in a sewing machine.

(Prior Art) Conventionally, devices for detecting bobbin thread breakage in sewing machines have been designed by touching the thread with a contact pin (for example, a thin metal rod) and directly receiving pressure from the thread. A piezoelectric material such as a ceramic vibrator was attached to the contact pin and the pressure exerted by the thread was detected as an electrical signal. However, with contact pins, the contact pin, which is placed near the middle between the lower surface of the throat plate and the outer circumference of the hook, comes into contact with the thread, which may cause the machine to sew poorly, and also prevent the thread from getting tangled with the contact pin. There is an inconvenience that the contact pin breaks, and there are also problems in those that use optical elements such as phototubes to determine thread breakage, such as loss of thread detection ability due to thread dust near the button type. was there.

In addition, since there is only a narrow space between the lower surface of the copper plate and the outer periphery of the hook in a sewing machine, it is extremely time-consuming to install one device d on the lower surface of the throat plate and the other device at the same time.

In order to solve this problem, increasing the distance between the lower surface of the nail plate and the outer periphery of the hook causes problems such as poor sewing quality and increased thread breakage.

(Problems to be Solved by the Invention) The present invention has an ultra-thin flexible piezoelectric element contact sensor attached to the back of the throat plate and integrated with the throat plate (by creating a ship thin piece sensor). A thread breakage detector is installed in the throat plate, which is almost the same as the conventional !1 temporary, and unlike the contact pin method, it does not have a negative effect on sewing results or thread breakage, and there is no damage to the contact pin. For example, since there is no one-area operating part such as striking the thread with a lever, it has a long life, and is completely free from the problem of the phototube method where the thread detection function is lost due to thread fuzz. To enable one device and another device to be installed at the same time without increasing the distance between the back surface of the throat plate and the outer periphery of the hook.

(Means for Solving the Problems) The present invention provides an upper thread and a lower thread that come into contact with the fins of the outer hook and are displaced in a direction perpendicular to the button type center when the outer hook rotates, relative to the outer peripheral position of the needle hole on the back of the throat plate. A thread contact sensor, which is a thin plate almost ring-shaped piezoelectric element that comes into contact with each thread and outputs a thread contact signal, is placed in close contact with the thread contact sensor, and the upper thread is brought into contact with the thread contact sensor at J3 during one cycle of the H rod's downward movement. outputs at least one timing signal of an upper thread contact tying signal and a lower thread contact timing signal at J3 during the period in which the lower thread contacts the thread contact sensor and the period in which the lower thread contacts the thread contact sensor, and outputs the upper thread contact timing signal. A method for detecting thread breakage in a sewing machine is characterized in that a thread breakage detection signal is generated whenever a thread contact signal is not outputted at the time of a thread contact timing signal or a bobbin thread contact timing signal.

(Example) Next, the configuration of an example of the present invention will be described with reference to the drawings.

t: 1 on the back of the throat plate 1, fin 3 of the outer hook 2 when the outer hook rotates twice
A thread contact sensor, for example a piezoelectric cord 7, in contact with the upper thread 5 and the lower thread 6 which are displaced in a direction perpendicular to the center of the needle hole 4, in this case a piezoelectric organic polymeric material as shown in FIG. A copolymer of nylidene fluoride and 37 dithylene fluoride P (
VDF/TrFE) is processed into a 50 micrometer thick noilum shape, which is electrochemically polarized, and a piezoelectric organic polymer material with a conductive material such as aluminum deposited as an electrode on the back side. The bimorph structure of the film 8 is a unimorph structure, and there is a sensing washer on the bottom surface of the film 8 that comes in contact with the thread, and the f washer is made of metal with a thickness of about 0.5 mm and is plated with hard chrome to give it wear resistance. Piezoelectric element 7 with 9 attached with electrically insulating adhesive, or as shown in FIG. 6B,
Attach the elastic to the center of the 1:1 hole 4 on the back of the needle jfi1 (
A sensing washer t14 pasted through a seal 13 with a thickness of about 0.1 mm, and the ranging washer 14
A cap 16 with a thickness of approximately 0.65 mm attached to the surface of the needle needle plate and a cap 16 formed on the cap 16 are in contact with each other through a rubber washer 15 having elasticity and a thickness of approximately 0.65 mm. The ring-shaped depression 17 has approximately 0.0 mm vertically.
A piezoelectric element 7 formed with a film 18 of a piezoelectric organic polymer material inserted with a gap of 1# is attached to a portion centered on the four holes 4 of the throat plate 1@ side with an electrically insulating adhesive. pasting′]
When the outer hook 2 is rotated in this pasted state, the thread 6 is
Between 63Q4 in FIG. 7, the needle thread 56 moves laterally as shown in FIG. 49
'' ~ 243° (shown between 45 and 49)), the bobbin thread 6 hooked to the outer hook 2 by the hook tip is pushed by the fin 3 of the outer hook 2 when moving in a loosened state, and t, 1 hole 4 right angle displacement in the direction.

Therefore, the outer hook 2 corresponds to 1 reel of the needle bar.
rotates twice] 0, needle bar 63°45'-49''~
Lower thread 6 at 108°45'49'', τ) 221815''49'' to 43 at 243°45-49''
Upper thread 5 is 243°45-49″288°
45-49'', the -F thread 5 and the bobbin thread 6 are displaced as shown by two-dot chain lines in FIGS. 5 and 6 and come into contact with the piezoelectric element 7.

As a result, when the outer hook rotates twice, it comes into contact with the fin 3 of the outer hook 2, and
When the upper thread 5 and lower thread 6, which are displaced in the direction perpendicular to the center of one hole 4, come into contact with the piezoelectric element 7 of the ranging washer, an electric signal is generated from the piezoelectric element 7 of the ranging washer. Since the upper thread 5 and the lower thread 6 vibrate in contact with the piezoelectric film 8 of the polymeric material 1, a micro-movement output is generated, and a vibration output due to vibration from the sewing machine body is also generated at the same time.

Next, FIG. 8 is an electric circuit diagram of this embodiment, in which the generated vibration output is led to the electric circuit through a lead wire 12 attached to an electrode. R1 is a resistor that matches the impedance of the piezoelectric film 8. C1 is a coupling capacitor that blocks the DC component of the imaging output. Di and D2 are half-wave rectifier diodes, which are also protection diodes that protect the OPl operational amplifier from excessive or insufficient input. 01fu1
is a Texas Instruments TLO94CN operational amplifier whose input stage is composed of FETs, which matches well with the high impedance output characteristics of the piezoelectric film 8.

OPI performs amplification and impedance conversion with an amplification factor of 1. The vibration output waveform that has passed through OPl mostly maintains its original shape, except for being half-wave rectified. The half-wave rectified vibration output contains not only the vibrations of the upper thread 5 and the lower thread 6 but also the vibrations of the sewing machine body, and it is difficult to determine whether the t-weft thread is IJ or not.

In the S dynamic output of the threads 5 and 6 and the photographic output of the sewing machine body, there is not only a difference in output level but also a difference in vibration frequency, so a bandpass filter for a specific band is installed in the circuit. Separate the vibration output of 6 and the w8 output of the sewing machine body. The circuit from R2 to OR3 is 1, and C5 is a coupling capacitor that blocks the C1 flow component after separation. OR3 is used as a comparator and determines whether or not there is an output of "C".

OR3, OR3 is 1 with the same operational amplifier as OPI.
Illumination using one circuit each of the four circuits in the package. 1
Also, 13, R14, TR1 is an interface to the thread signal receiving circuits RS and F of the sewing machine main body using a resistor and a transistor.

In this example, the piezoelectric body is made of vinylidene fluoride and ethylene trifluoride, which are piezoelectric polymer materials.
Although W combined P (VDF/TrFE) is used, the 11-electrolic organic, single-molecule materials in the song, such as polyvinyritine fluoride medium combined (PVDF), are also used for J:<, vinylidene cyanide and vinyl acetate. Polymer P (VDCN/VA
c) etc. Alternatively, it may be a flexible polymer composite piezoelectric material 4r in which fine particles of Relamic piezoelectric abrasive are dispersed in a fluorine-based polymer (for example, Daikin Industries, Ltd. [Biesel JR]). Further, the sensing washer 9 may be made of a metal-substitute polymeric material (for example, polycarbonate, polyaretal, etc.) or a ceramic material for a separate structure. Alternatively, the base material may be plated or the like. Further, the shape does not have to be completely circular.

In addition, if this detector is equipped with an angle timing generator AD that generates a rotation angle signal in conjunction with the main shaft of the sewing machine, the circuit from R15 in Fig. 8 can be installed. It is possible to distinguish and detect 6 cuts of the lower thread and 51 cuts of the upper thread.

As mentioned above, in the output stage of OPl, the vibration output waveform is as shown in A of FIG. 9. As shown in the upper part of FIG. By setting 〇 to the angle timing generator to generate angle timing in the range of thread 6 detection, the vibration output capture timing of threads 5 and 6 (bobbin thread 6, upper thread 5, upper thread 5 lower thread 6 detection) range)
As a result, the inverter output of ITl is inverted, so R8
The output from the TRI transistor is taken into the F flip-flop. The thread 5.6 signal taken into R3F is sent to IT
2 to [T4] At the end of each capture timing, the one-shot signal generated by the circuit from IT3 to [T5 is captured into the D latch of DFL, f) F2, Ll, L2
It is displayed on the lamp. D5. The anode side terminal of the diode D6 is an output terminal to the sewing machine controller. The signal waveform until it is taken into R3F is as shown in FIG. A is the output stage of 01]1, B is the + side input terminal of OR3, and the thread self-illumination (waveform before comparison, C is the TRI
This is the emitter side output of , and is a thread presence signal at L level. This thread presence/absence signal is taken into the aforementioned R3F and processed.

To explain the above process in more detail, first, when the power is turned on and the sewing machine starts operating, the 4 rods move up and down in one cycle.
The outer hook 2 rotates twice for each rotation of the main shaft of the sewing machine, and the upper thread 5 and lower thread 6 are both in a state where they are not broken.
The piezoelectric element 7 outputs the output shown in FIG. 63'45"49" to 108°45-49 touching 7
'', actually 90' to 120 degrees due to the delay due to spindle rotation
and 221'15- where the needle thread 5 contacts the piezoelectric element 7.
49" to 243° 45-49", actually between 225° and 255° from the same delay as above, and 243° 45-49" to 28 when both upper thread 5 and lower thread 6 contact piezoelectric element 7
8°45-49″, actually about 2 from the same radius as above.
55° to 3200 degrees, the output of the rHJ level, in fact, the contact of the thread 5.6 to the piezoelectric element 7 is vibrating, so a vibration output is generated, and the signal output from the comparator OP3 is Batsufu 1TR
Inverted by I.

On the other hand, the terminal T1 of the angle timing generator AD outputs the r l - I J level between 60' and 1 (0 degrees) of the main shaft corresponding to the detection of the lower thread breakage, and the terminal T2 outputs the r l - I J level corresponding to the detection of the upper thread breakage. 2000-2400 of the main axis corresponding to
Since the rHJ level is output in between, a timing pulse is output from IT5 of the one-shot circuit via transistor TR3 every time the terminal T1 output falls, and a timing pulse is output from IT5 of the one-shot circuit via transistor TR2. A timing pulse is output from the ITJ every time the output from the terminal T2 falls, and each timing pulse is input to the CK terminals of the corresponding DF1 and DF2.

Therefore, both the upper thread 5 and the lower thread 6 are in a state where they are not broken, and first, when the spindle rotation angle is 00 to 600, the terminal T
1. When both T2 outputs are rLJ, the reset input of R3F is "L" and the Q output of R8F is "H", then when the spindle rotation angle is 60' to 100 degrees and the terminal lower 1 output is 11', The reset input of R8F becomes "I" and when this reset input is "H", the output from the comparator OP3 which is used to detect the bobbin thread 6 becomes rLJ, so the R8F output is reversed and the main force of the stone becomes "Shi". Mutual main power r L J period-
During this period, the terminal T1 output becomes rLJ, a timing pulse is generated from lT5 of the one-shot circuit, and the "Yes" level is manually input to the reset terminal of R3F. Since the input is performed manually with a slight delay due to the R25 and C6 time constants, when the D input of DFl reaches rLJ, the CK input of DFl rises, and the Q output of DFl becomes "L".
'' level is maintained, the bobbin thread breakage indicator lamp L2 does not light up, and no external output for stopping the sewing machine is generated.

Similarly, when the spindle rotation angle is 2000 to 2400, d3 - (DF2
The timing pulse is manually applied to the CK @ child of DF2, and the Q of DF2 is
The output maintains the rLJ level as described above, the needle thread breakage indicator lamp 1 does not light up, and no external output for floating the sewing machine or the like is generated.

Also, the spindle rotation angle is 2400~320° and 3500~3
Although the rLJ output is generated from the comparator OP3 even between 0' and 0', the timing generator A[
), the reset input of R3F remains at rLJ level, and each DF1, 1. )F2
Since there is no pulse output to the CK terminal of each DFI, D
The Q output of F2 maintains the rll level by 1.,1.

In this way, in the condition of thread breakage (,1, corner!9
R3 by timing output from timing generator 80
At the time of F reset input "T1", the [L] output from comparator OP3 due to thread detection is input to the reset 1 terminal of R3F, and the Q output of R3r- changes from "H" to "["
However, when the upper thread 5 and the lower thread 6 are in a state where the upper thread 5 and the lower thread 6 are cut, one of them is broken. d3C is the timing output from the angle timing generator △1] that corresponds to each thread breakage detection.
Comparator for J5 at the time of "F relet human power 1-H" ○
The output of P3 remains at the "I" level, and the R3FQ output maintains the rHJ level.

As a result, when thread breakage occurs, a timing pulse is generated for the R3FQ output at the "day" time point, and in the case of upper thread breakage, the Q output of DF2 is generated, and in the case of bobbin thread breakage, the Q output of DF1 is generated.
As soon as the outputs are inverted and reach the "1" level, each loop L1. In addition to lighting L2, a signal for stopping the sewing machine, etc. is output to the external circuit.

(Effects of the Invention) By incorporating an ultra-thin sensor into the throat plate, the present invention can detect thread breakage in the same state as when a conventional throat plate is installed, and the thread breakage detector and other devices can be used to detect thread breakage. It is possible to equip both the throat plate and hook at the same time. Also, since the sensor has flexibility f1, is there a difference in the needle plate when the needle penetrates the fabric every time the sewing machine stitches or when the presser foot temporarily hits the button? ! The sensor body will not be damaged during shooting. The piezoelectric organic polymer material used for the sensor is flexible and easy to mold and cut 1101, and is easier to manufacture than the conventional sensor υ-. Further, it is effective in eliminating the drawbacks of the conventional anti-opulsion methods such as the contact pin type and the photoelectric tube type.

[Brief explanation of drawings]

Fig. 1 is a front view of 4-handling 1 of one embodiment of the present invention, Fig. 2 is a sectional view taken along the line X-X of Fig. 1, Fig. 3 is a front view of the whole device, and Fig. 4 is its plane. Figure 5 is a side view of the same, Figure 6 is a detailed view of its main parts, Figure 7 is an explanatory diagram of its mechanical operation, Figure 8 is its electrical circuit diagram, and Figure 9 is its electrical operation diagram. It is. 1...Needle plate 2...Outer hook 3...
・Fin 4...Fin hole 5...Top
Thread 6...Bottom Thread 7...Piezoelectric element Applicant Tokai Kogyo Sewing Machine Co., Ltd. Agent Patent attorney Oka 1) Hidehiko Figure 1! 2 了'iKa ~A Figure 6 ``!

Claims (1)

[Claims] A thin plate that outputs a thread contact signal by contacting each of the upper thread and lower thread, which are displaced in a direction perpendicular to the center of the needle hole by contacting the fin of the outer hook when the outer hook rotates, relative to the outer peripheral position of the needle hole on the back of the throat plate. The thread contact sensor, which is an approximately ring-shaped piezoelectric element, is brought into close contact with the thread contact sensor, and the needle thread is kept in close contact with the thread contact sensor during one cycle of vertical movement of the needle bar. A thread breakage detection signal is generated when at least one of the contact timing signal and the bobbin thread contact timing signal is output, and the thread contact signal is not output at the time of the upper thread contact timing signal or the bobbin thread contact timing signal. A method for detecting thread breakage in a sewing machine, characterized in that thread breakage occurs in a sewing machine.