JPH0345765A - Device for detecting breakage of yarn in warp-knitting machine - Google Patents

Abstract

PURPOSE:To highly accurately detect the breakage of a yarn, lighten the load of maintenance and installation and lower troubles because of not requiring any other device by recognizing the abnormal pattern of light quantity change in a knitting region between each reed and each knitting needle to detect the breakage of the yarn. CONSTITUTION:An optical axis between a light transmitter 1 and a light receiver 2 is set in a knitting region meaning a space between the reeds of a warp- knitting machine and the knitting needles thereof disposed below the reeds and is extended in parallel to a warp-arranging direction. Since the abnormal pattern of the change in the quantity of light in the knitting region between each reed and each knitting needle is recognized and the breakage of the yarn is detected, the breakage of the yarn is surely detected.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a yarn breakage detection device for a warp knitting machine.

[Prior Art] Conventionally, a yarn breakage detection device has been used to detect yarn breakage in warp knitting machines such as tricot knitting machines, Raschel knitting machines, and Melanese knitting machines.

This thread breakage detection device is used for the four types of vertical ICIN shown in Fig. 12. ', -\ Four pairs of light transmitting devices and light receiving devices (not shown) in which light beams Lb1 to Lb4 are set above 201 to 204 to transmit and receive light, and light beam Lb1
- Air supply device 300 that blows out an air flow in a direction perpendicular to the arrangement direction of each warp group 101 to 104 so as to cross Lb4
and thread breakage detection means (not shown) that detects thread breakage by detecting that the amount of light received by the light receiving device has decreased by a predetermined value or more.

To explain in more detail, each warp group 101 to 104 is guided by each warp thread 201 to 204 and supplied to the knitting needles 400 of the warp knitting machine, and the light beams Lb1 to Lb4 are emitted in the vicinity of each warp thread u101 to 104. Each warp group 101~
104 extends parallel to the arrangement direction. Then, when one warp thread is cut, the end of the cut warp thread is transferred to the air supply device 300.
The yarn breakage detecting means detects a yarn breakage by the decrease in the amount of light caused by the crossing of the light beams Lb1 to Lb4.

[Problems to be Solved by the Invention] However, the yarn breakage detection device of the warp SUN described above may not be able to detect yarn breakage, and if yarn breakage cannot be detected, the knitting of the warp knitting machine continues as is. This resulted in a large amount of defective products and associated expenses.

Possible reasons for this are as follows.

The first reason is that a broken warp can only be exposed to the light beam Lb1~ once.
Since Lb4 is not crossed, detection errors are likely to occur.

The second reason is that as the warp thickness becomes thinner, the change in the amount of light when the cut warp crosses the light beams Lb1 to Lb4 decreases.

The third reason is that depending on the circumstances of thread breakage, the ends of the broken warp threads may not cross the light beams Lb1 to Lb3. In an actual example, a broken warp thread may become entangled with an adjacent normal warp thread and be drawn into a knitting needle, and in this case, the air flow may bias the broken warp thread in a direction perpendicular to the light beams Lb1 to Lb4. Therefore, optical axis crossing by broken warp threads does not occur.

The present invention has been made in view of the above problems, and an object to be solved is to provide a thread breakage detection device for a warp knitting machine that is capable of detecting thread breakage with high accuracy.

[Means for Solving the Problems] The thread breakage detection device for a warp knitting machine of the present invention includes a light transmitting device whose optical axis is set along the arrangement direction of each warp thread of the warp knitting machine and transmitting and receiving light; In a thread breakage detection device for a warp knitting machine, comprising a light receiving device and a thread breakage detection means for detecting thread breakage of the warp yarns based on a change in the light amount of the light receiving device, the optical axis of the pre-delivery light device and the light receiving device is It is characterized in that it is set in a knitting area between each reed that guides each warp, and a knitting needle that is disposed below each reed and knits each warp.

The knitting area refers to a space that is positioned between the warp knitting machine and the knitting needles disposed below the knitting machine, and extends parallel to the array directions of the warp, the knitting needles, and the knitting needles. This knitting area is a space where warp yarns are placed and knitting is performed by knitting needles.

The light transmitting device may have a light emitting element such as a light emitting diode, a laser diode, etc., and the light emitting element may be operated continuously or may be modulated at a predetermined frequency. The light receiving device can have a photoelectric conversion element such as a photodiode or a phototransistor.

In a preferred embodiment, the light transmitting device is capable of outputting carrier light that is pulse modulated or sinusoidally modulated at a predetermined carrier frequency. In this case, since the carrier light is AM-modulated by the periodic movement of the warp threads, the detection means tunes and amplifies the output signal of the light receiving device using the carrier frequency as a tuning frequency, and then detects the signal related to the periodic movement of the warp threads. can be detected with a high signal-to-noise ratio. However, the carrier frequency of the carrier light needs to be set sufficiently higher than the fundamental frequency of the electric signal (hereinafter referred to as warp signal) corresponding to the periodic motion of the warp threads.

It is preferable that the yarn breakage detection means includes a waveform change detection means for extracting a change in the circumferential movement of the warp yarns in the knitting area, and a discrimination means for determining yarn breakage based on the degree of change in the periodic movement pattern.

The thread breakage detection means compares a modulation signal modulated by the warp periodic movement pattern with a standard modulation signal modulated by the standard periodic movement pattern, and determines thread breakage based on the degree of difference in waveform. can do. - In an example, the waveform change detection means can binarize the modulated signal using a predetermined threshold voltage and convert it into a pulse signal.

In this way, a change in the waveform of the modulation signal due to a change in the periodic motion pattern of the warp threads can be converted into a change in the duty ratio of the pulse signal, allowing simple and highly accurate detection.

The determination means compares the duty ratio of the pulse signal with the standard duty ratio of the pulse signal when the warp knitting machine is operating normally, and if the difference between the two is greater than a predetermined value, thread breakage is detected. can be determined.

The waveform of the modulation signal varies depending on the type of warp knitting machine. In a simple example, each pulse of the pulse signal has the same duty ratio during normal operation.

However, since the periodic motion pattern of the warp threads is generally complex, the duty ratio of the pulse signal has a predetermined variation pattern that is repeated every N pulses (N is an integer of 2 or more). - In the example, this periodic change pattern of the duty ratio is stored in advance, and compared with the actual periodic change pattern of the measured duty ratio, and if the difference is large, thread breakage is determined. I can do it.

[Operation] In the thread breakage detection device for a warp knitting machine of the present invention, the optical axis of the light transmitting device and the light receiving device is located in the space between the reed of the warp knitting machine and the knitting needles disposed below the reed. It is set in a knitting area that means , and extends parallel to the warp arrangement direction.

During normal knitting without yarn breakage, the warp yarns are driven by the arbor and knitting needles and move along a predetermined movement trajectory in the knitting area. This locus of motion is repeated at a constant period (referred to as the knitting cycle period), so the warp threads modulate the light from the light transmitting device passing through the optical axis at the knitting cycle period, and the light receiving device that receives the modulated light modulates the light at the knitting cycle period. A modulated signal with a predetermined waveform that is repeatedly modulated is output. Then, the thread breakage detection device detects that the waveform change of the modulation signal is small and
It is determined that there is no thread breakage.

If a thread breakage occurs and the broken warp does not intertwine with the adjacent warp, the warp that was originally supposed to be knitted with the broken warp remains unknitted, and this affects the movement trajectory of the remaining warp threads. changes compared to normal conditions. Also, when a thread breakage occurs and the broken warp becomes entangled with an adjacent warp, the warp that was originally supposed to be knitted with the broken warp remains unknitted, and the broken warp becomes entangled. , the movement trajectory of each warp thread changes compared to the normal one. Due to such an abnormal movement locus of the warp threads, the light receiving device outputs a modulated signal with an abnormal waveform, and the thread breakage detection means detects a "thread breakage" from the abnormal waveform of the input modulation signal.

[Example] (Example 1) An example of the yarn breakage detection device for a warp knitting machine according to the present invention is shown in the circuit diagram of FIG.

This yarn breakage detection device for a warp knitting machine is comprised of a light transmitting device 1 and a light receiving device @2 that are installed in a jacquard raschel machine (not shown), which constitutes a type of warp knitting machine, and that transmit and receive light. Device 2
a waveform change detection means 3 for extracting a change in the periodic movement pattern of the warp from the output signal of the output signal; a discriminating means 5 for determining yarn breakage based on a change in the extracted periodic movement pattern; and an indicator 6 for indicating the presence or absence of yarn breakage. Consisting of Note that the waveform change detection means 3 and the discrimination means 5 constitute thread breakage detection means in the present invention.

The light transmitting device 1 and the light receiving device 2 are disposed facing both ends of the Jacquard Russell machine in the warp arrangement direction. As shown in FIG. 2, the light beam L of the light transmitting device] and the light receiving device 2 is transmitted to the space between the reed group 7 of the Jacquard Russell machine and the knitting needles 8 disposed below the reed group 7. This is set in the composition area 9, which means . The light transmitting device] has a laser diode (not shown) and a lens system that narrows the light into a beam of 10 to 20 φ. The light receiving device 2 has a phototransistor (not shown) and a lens system that focuses light on the phototransistor. Since other details of the light transmitting device 1 and the light receiving device 2 are well known, their explanation will be omitted.

The waveform change detection means 3 includes a tuned amplifier circuit 3a, a bandpass filter 3b, a limiter 3C1 detector 3d, and a low-pass filter 3e.
, and a binarization circuit 3f. The binarization circuit 3f includes a low-pass filter 31, a level shifter 32, and a comparator 3.
It is composed of 3.

The determining means 5 is composed of a microcomputer, and the light transmitting device 1
and drives the indicator 6.

The indicator 6 consists of a buzzer and a red lamp.

The operation of the thread breakage detection device of this warp knitting machine is shown below in Figure 1.
This will be explained with reference to FIG.

The determining means 5 controls the light transmitting device 1 to emit pulsed light at the frequency of the mouth Z as shown in Equation 10. As shown in FIG. 2, the light beam emitted from the light transmitting device extends through the knitting space 9 between the stitch 7 and the knitting needles 8 in the warp arrangement direction. The warp threads 10 kited by the blade 7 are placed in this knitting space 9.
It is knitted using knitting needles 8. Since the knitting operations of various warp knitting machines including this Jacquard Russell machine are well known, detailed explanation thereof will be omitted. However, due to the knitting operation of the knitting needles 8, the warp yarns 10 in the knitting space 9 repeat the same movement locus at a predetermined knitting cycle period. The light beam passing through the knitting space 9 is modulated by this locus of movement of the warp threads 10, with the knitting cycle period as a unit period. The modulated light beam is photoelectrically converted by the light receiving device 2, and the light receiving device 2 sends a modulation signal Sn to the tuned amplifier circuit 3a. “The tuned amplifier circuit 3a tuneably amplifies the modulated signal @sn at a tuning frequency of several tens of kHz, and furthermore, the bandpass filter 3b, which has a pass band of approximately 10kHz±1, removes unnecessary frequencies from the tunedly amplified modulated signal Sn. The necessary band components of the modulated signal Sn extracted by the band filter 3b having a pass band are:
The limiter 3C keeps the size within a certain range. That is, since ripple components, noise components, etc. are superimposed on the necessary band components of the modulation signal Sn, excessive high-level voltage values and insufficient low-level voltage values are cut by the limiter 3C. The limiter 3C is composed of, for example, an anti-parallel diode connected between a signal line and a ground line.

The necessary band components from which superimposed noise has been removed by the limiter 3C are detected by the detection circuit 3d, unnecessary high-frequency components and carrier components are cut by the low-pass filter 3e, and only the effective low-frequency components are extracted as the modulation signal Sm. be done. In this embodiment, the cutoff frequency of the low-pass filter 3e is set to about the IK port Z.

Next, the modulated signal Sm is input to the binarization means 3f. First, the low-pass filter 31, which has a pass band of about several tens of degrees 2, extracts a pseudo DC component (more precisely, a very low-pass component of, for example, several tens of degrees 2 or less) from the modulated signal sm. This pseudo-DC component includes an extremely low frequency component that inevitably occurs due to changes in yarn quality and knitted fabric width. Note that it is advantageous to set the cutoff frequency of the low-pass filter 31 to be equal to or higher than the commercial frequency because the flicker component of the lighting equipment can be removed by the comparator 33.

The pseudo DC component output from the low-pass filter 31 is level-shifted by a predetermined amount by a level shifter 32 and converted into a threshold voltage yth.

As the level shifter 32, a well-known circuit configuration using a constant voltage diode or a Schottky diode can be adopted. Note that here, the threshold voltage yth is almost equal to the modulation signal @Sn
The circuit constants are set so that the

, the comparator 33 compares the threshold voltage Vth output from the level shifter 32 with the modulation signal Sm, binarizes the modulation signal @Sm, and generates a pulse signal Sp. The pulse signal SF) is input to the determining means 5, which determines yarn breakage based on the degree of change in the duty ratio of the pulse signal and drives and controls the indicator 6.

FIG. 3 shows voltage waveforms at various parts of the circuit shown in FIG. 1.

In this embodiment, the modulation signal Sn has only one peak in one train cycle Ty.

The operation of the discriminating means 5 composed of a microcomputer will be explained with reference to the flowchart of FIG.

First, it is initialized at 5200, and flag F and count variables N and M are cleared and set to O.

Next, it is checked whether the rising edge ELJ (see Figure 2) of the pulse signal @Sp has been input (S202).E
If u is not input, it remains on standby, and if Eu is input, it is checked whether flag F is 1 (S204). Note that the flag F is a flag that is set when the duty ratio of the pulse signal Sp is abnormal. If flag F is set, the count variable N is set to N+1 and the process proceeds to 8208; if flag F is not set, the process directly proceeds to 3208. Note that the count variable N counts the total number of input pulses after an abnormality in the duty ratio is detected.

At 5208, the duty ratio τ of the pulse signal Sp is detected. To calculate the duty ratio τ, find the pulse width A of the pulse signal Sp input immediately before and the pulse cycle day (=1 train cycle cycle time Ty), and then the duty ratio τ=
All you have to do is find A/B. Actually, a timer built in the discriminating means 5 detects the rising edges Eu that are adjacent to each other.
- Eu to find the pulse period B (see Figure 3), then count the time between the rising edge Eu and the subsequent falling edge Ed to find the pulse width (see Figure 3). ) and find the duty ratio τ=A/B
Calculate. Note that in the first cycle after the routine starts, there is no pulse input immediately before, so the duty ratio τ becomes O, but this will be excluded in later processing.

Next, the absolute value of the difference between the calculated duty ratio τ and the standard duty ratio τO stored in advance is determined, and it is determined whether this absolute value is greater than or equal to a predetermined value (S210
). If this absolute value is smaller than a predetermined value, the duty ratio τ is determined to be normal and the process returns to 5202. If this absolute value is greater than or equal to the predetermined value, the flag F is set to 1 and the count variable M@M+1 is set to proceed to 8216. Note that M is 5
The number of times an abnormality in the duty ratio τ determined in step 210 has occurred is shown.

In 8216, N is 6J'1. Check if it is above, and if N is 5 or less, return to 5202, and when N reaches 6, 1'
If so, it is checked whether M is 3 or more (S218). 521
6 and 5218, the abnormality of duty ratio τ is 321
It is checked whether three or more pulses among the six pulses input after being detected as zero have an abnormal duty ratio. Incidentally, an abnormality in the duty ratio of one or two pulses among the six pulses is ignored in this embodiment as an accidental error.

If M is below 2J and 4 in 5218, set F, M, and N as ○.
is cleared and returns to 5202, and if M is 3 or more, the indicator 6 is driven to warn the operator of thread breakage.

This embodiment described above has the following features.

(a) Since the threshold level vth is changed based on the pseudo DC component extracted from the modulated signal @Sm, the comparator 33 changes the warp, changes the knitted fabric width, and changes the model of the warp knitting machine. Despite this, it is possible to prevent the discrimination accuracy from deteriorating and to always reliably detect yarn breakage in the warp group even with the S adjustment.

(b) Since yarn breakage is detected based on an abnormality in the duty ratio, the inspection accuracy is high and the circuit configuration is simple.

(C) 6 input after detecting an abnormality in duty ratio
Since thread breakage is determined when the duty ratio of three or more pulses is abnormal during the pulse, sudden abnormalities in the duty ratio can be excluded and malfunctions are reduced.

(Embodiment 2) Another embodiment of the thread breakage detection device for a warp knitting machine according to the present invention is shown in FIG.

This warp group shedding defect detection device includes a light transmitting device 1, a light receiving device 2, a low pass filter 3d for extracting the low frequency component of the modulated signal Sn output from the light receiving device @2, and a low frequency component of the extracted low frequency component. A/D that converts the component A/D and outputs the modulated signal Sn-
It consists of a converter 4, a discriminating means (microcomputer) 5 for determining thread breakage by controlling the modulation signal 3n'', and an indicator 6 driven and controlled by the discriminating means 5, and the circuit configuration of the first embodiment is further modified by a microcomputer. It has become.

The operation of the determining means 5 will be explained with reference to the flowchart in FIG. However, it is assumed that the light receiving device 2 outputs the modulated signal Sn shown in FIG.

First, initialization is performed (8100), and the modulation signal 3n' is read (S102). Thereafter, periodically interrupt routine 5
200 and periodically reads the modulated signal 3n-.

Next, it is checked whether the modulation signal @Sn- is larger than the threshold Th (that is, whether the rising edge Eu of the pulse is input) (S104), and if Sn->Th, the pulse is input 5106 and starts counters A and B built in the microcomputer (S1
06). The threshold value Th is the average value M plus the bell shift value ΔX
The average value M is the average value (pseudo DC component in Example 1) of the modulation signal 3n- input in the period 1 second before the current time.However, at the beginning of operation, the previous operation stop The previous average ifiMx is memorized and used as the average value M.Furthermore, if the average value Mx falls outside the predetermined range due to a power outage or other reasons, a predetermined average value MC set in advance is used as the average value. Used as M.

Further, the level shift value ΔX is a predetermined value stored in advance in the microcomputer 8, the counter B is a counter that measures the pulse period B (see Fig. 3), and the counter A is a counter that measures the pulse width A (see Fig. 3). This is the counter where you read it.

Next, it is checked whether the modulation signal Sn- is below the threshold value Th, that is, whether the falling edge Ed of the pulse has been input (S108), and if it is below, the counter A
Clear the counter A (S110).

Next, it is checked whether the modulation signal SN- is larger than the threshold value Th again (S112), and if it is larger, it is assumed that the rising edge Eu of the pulse has been input again, and after storing the count value of the counter B, the counter Clear B (S114).

Next, the duty ratio τ is calculated (S116).

Naturally, the duty ratio C is the value stored in counter A divided by the value stored in counter B.

Next, it is checked whether the absolute value of the difference between the standard duty ratio τO stored in advance in the determining means 5 and the calculated duty ratio τ is greater than or equal to a predetermined value R (S118>; if it is, the duty ratio τ is abnormal. If the duty ratio τ is smaller than the predetermined value R, it is assumed that there is no thread breakage and a new average value M is calculated (Sl 20). A new threshold value Hh=average value M+level shift value ΔX is calculated (5122), and a light emission output control signal is output to the light emitting device @1. It should be noted that this light emission output control signal is obtained by averaging the modulation signal Sn' input during one hour and calculating the reciprocal thereof, and the light emitting device 1 emits light in proportion to this reciprocal. However, for the first hour after starting the operation of the warp knitting machine,
The light emitting device 1 emits light in proportion to the reciprocal number obtained in the last hour of the immediately preceding operating period, and furthermore, if the reciprocal number deviates from a predetermined range, a preset value is used as the light emission output control signal. S'' is output to the light emitting device 1.

Thereafter, the process returns to 3106 and the routine is executed again.

In this way, the circuit can be constructed almost entirely from a microcomputer, and since the light emitting output of the light emitting device is made proportional to the reciprocal of the long-term average amount of light received, the average value of the modulation signal Sn' can always be kept constant. Can you hold it?

(Embodiment 3) Still another embodiment of the yarn breakage detection device for eight warp machines of the present invention will be described.

This yarn breakage detection device for a warp knitting machine has the same circuit configuration as the yarn breakage detection device for a warp knitting machine according to the first embodiment shown in FIG. Only that is different.

In the yarn breakage detection device for the warp knitting machine of this embodiment, the light of the received light beam is modulated by the knitting needles 8 and the grain 7, and as shown in FIG. 8, three peaks P1, P1, P
2. I have P3. For example, in a tricot machine, the knitting needles, bruises, sinkers, plexers, etc. have complex motion trajectories, and depending on the position setting of the light beam L, the light beam L can be moved by the knitting needles, bruises, sinkers, plexers, etc. in addition to the warp group. In some cases, the light beam L is blocked, in which case the light beam L is modulated into a complex waveform as shown in FIG. 8, for example.

The operation of the discriminating means 5 composed of a microcomputer will be explained with reference to the flowchart of FIG.

First, initialize the built-in counters C1 and C2 on the 3300.
and count variables N and M are cleared and set to O.

Next, it is checked whether the rising edge Eu of the pulse signal Sp is input (S302>. The rising edge Eu
If Eu is not input, it remains on standby, and if Eu is input, it starts counters C1 and C2 (S304),
It is checked whether the falling edge Ed of the pulse signal Sp is input (S306). Note that the counter C1 is a counter that counts the pulse widths Ta, Tc, and Te of the pulse signal Sp, and measures the interval from the rising edge Eu to the falling edge Ed. Further, the counter C2 is a counter that counts the pulses Tb, Td, and Tf of the pulse signal Sp, and measures the interval from the rising edge Ed to the next rising edge EIJ.

If the falling edge Ed is not input in 5306, it waits until the falling edge Ed is input, and if the falling edge Ed is input, it stops the counter C1 and stores the count value (pulse width), and , reset the counter C1 to O.

Next, it is checked whether the rising edge Eu of the pulse signal Sp has been input again (S310).

If the rising edge Eu is not input, it remains on standby, and if the pulse signal Sp is input, it stops the counter C2, stores the count value (pulse frequency l1ll), and resets the counter C2 to O (S312 ).

Next, in 5314, set the count variable N to N+1 and 831
Proceed to step 6, check whether the count variable N has become 3, and if N is not 3, return to 5302, and if N is 3, clear N to O (S318), and set the duty ratio τ.
1, τ2, and τ3 are calculated (320).

Here, the count variable N is used to check whether the number of input pulses has reached 3 or not.

That is, in this embodiment, as shown in FIG. 8, three pulses Pa, Pb, and pc are generated in one knitting cycle Akima Tx. The fact that N has become 3 means that three pulses Pa, Pb, and Pc have been input in sequence, and one knitting cycle period Tx=pulse period B has ended.

Naturally, when N reaches 3, the microcontroller's built-in register contains the pulse width 1' of each pulse Pa, Pb5PC.
-a, Hb, Tc and pulse intervals Tb, Td, Tf are stored. Note that τ1=Ta/Tb, z:2=Tc
/Td, τ3-Te/Tf.

Next, the standard duty ratio τ1n of the pulse pa stored in advance is compared with the duty ratio τ1, and the duty ratio τ2n of mark i (of the pulse pb stored in advance) is compared with the duty ratio τ2. The standard duty ratio τ3n of the pulse PC that is being used is compared with the duty ratio τ3 (S322).Specifically, these comparisons are made based on the difference between the respective duty ratios (τ1n-τ1), (τ2nτ
2), is executed by checking whether the absolute value of the difference between (τ3n−τ3) is larger than a predetermined value.

If even one of the duty ratios τ1, τ2, τ3 deviates from the normal duty ratios τ1n, τ2n, τ3n by more than the predetermined value, it is considered as an abnormality of the duty ratio.
24, count variable M is set to N+1 with advance/ν (S32
4), proceed to 3326.

Note that M indicates the number of times an abnormality in the duty ratio has occurred.

If all of the duty ratios τ1, τ2, and τ3 are not deviated from the standard duty ratios τ1n, τ2n, and τ3n by more than the predetermined value, the duty ratios are determined to be normal and the process returns to 5302.

At 8326, it is checked whether the microcomputer's built-in timer is operating. Note that this timer is a timer that operates at 8330 after the duty ratio abnormality is detected at 5322, and sets a certain duty ratio abnormality inspection period after the duty ratio abnormality is detected.

In this example, this timer is set to 3Tx (=3B>).

If the timer is in operation at 5326, the process returns to 5302; if the timer is not in operation (in other words, if the timer is running or finished), it is checked whether M is 2 or more (3328). If the count change 1aM is 2 or more, it means that the duty ratio abnormality has been detected in the light interval of the 2nd formation cycle during the 3 consecutive formation cycle period (3Tx>) after the duty ratio abnormality occurred. drive the indicator 6 to warn the operator (3)
332) End the routine. On the other hand, if M is less than 1, it is assumed that there is no thread breakage, the above-mentioned timer is started, M is cleared to O, and the process returns to 53O2.

According to the third embodiment described above, even if the modulation signal Sn
has a plurality of peaks (e.g., Pl, P2, Pa in FIG. 8) during one knitting cycle, and accordingly, the pulse signal Sp has a plurality of pulses each having a different duty ratio (e.g., Pl, P2, Pa in FIG. 8) during one knitting cycle. Even if the yarn contains threads (Pa, Pb, PC in Fig. 8), thread breakage can be detected normally.

In addition, in Jin's embodiment, the indicator 6 is activated only when the duty ratio abnormality is detected two or more times during the three consecutive formation cycles after the duty ratio abnormality is detected.
, the indicator 6 is less likely to malfunction due to an accidental trouble.

Note that SL shown in FIG. 3 indicates the lower limit level of the limiter 3C, and S2 indicates the upper limit level of the limiter 3C. Similarly, S3 shown in FIG. 8 shows the lower limit level of the limiter 3C, and S4 shows the upper limit level of the limiter 3C.

Sl shown in FIG. 3 exceeds the lower limit level of the limiter 3C, and S2 exceeds the upper limit level of the limiter 3C.

In addition, in each of the above embodiments, thread breakage is detected due to an abnormality in the duty ratio, but if the circuit processing becomes complicated,
Yarn breakage can also be detected based on the degree of correlation between the standard waveform of one knitting cycle stored in advance and the actual waveform of the modulation signal S n of one knitting cycle.

The position of the light beam L in other warp knitting machines is shown in Figure 9 and Figure 1.
0 and 11.

[Effects of the Invention] As explained above, the yarn breakage detection device for the warp knitting machine of the present invention detects yarn breakage by identifying an abnormality in the light intensity change pattern in the knitting area between each reed and each knitting needle. Because I am doing
It is possible to reliably detect yarn breakage, which has great industrial benefits.

In other words, the present invention detects abnormal light modulation waveforms caused by broken warp fragments and abnormal light modulation waveforms caused when broken warp threads are entwined with adjacent normal warp threads. Since the presence or absence is not detected, thread breakage can be detected with high precision even if the warp threads are thin or the broken warp threads get entangled with other warp threads or come off from bruises.

Furthermore, in the present invention, only one set of the light transmitting device and the light receiving device is required, which reduces the burden of maintenance and installation, and reduces the failure rate.

[Brief explanation of drawings]

1 is a block diagram showing the first embodiment of the present invention, FIG. 2 is a schematic diagram showing the position of the light beam L, FIG. 3 is a signal waveform diagram of each part, and FIG. 4 is a diagram showing the operation of the discriminating means 5. 5 is a block diagram showing the second embodiment of the present invention, FIG. 6 is a flow chart of the second embodiment, FIG. 7 is a block diagram showing the second embodiment of the present invention, and FIG. 8 is a block diagram showing the second embodiment of the present invention. The Kakubu signal waveform diagram in FIG. 7, FIGS. 9, 10, and 11 are schematic diagrams showing the position of the light beam L in other warp knitting machines. FIG. 12 is a schematic diagram showing the position of the light beam L of a conventional yarn breakage detection device. 1... Light transmitting device 2... Light receiving device 3... Waveform change detection means (thread breakage detection means) 5...
Discrimination means (thread breakage detection means) 6... Indicator

Claims (5)

[Claims] (1) A light transmitting device and a light receiving device whose optical axes are set along the arrangement direction of each warp thread of a warp knitting machine to transmit and receive light, and a thread that detects thread breakage of the warp threads based on changes in the light amount of the light receiving device. In the yarn breakage detection device for a warp knitting machine, the optical axis of the light transmitting device and the light receiving device is arranged below each reed that guides each warp yarn, and the optical axis of the light transmitting device and the light receiving device is A yarn breakage detection device for a warp knitting machine, characterized in that it is set in a knitting area between knitting needles that knit each warp yarn. (2) The yarn breakage detection means includes a waveform change detection means for extracting a change in the periodic movement pattern of the warp yarns that is repeated in the knitting area, and a discrimination means for determining yarn breakage based on the degree of change in the periodic movement pattern. A yarn breakage detection device for a warp knitting machine according to claim 1, comprising: (3) The waveform change detection means includes a circuit that binarizes the modulated signal output from the light receiving device, and the discrimination means includes:
The yarn breakage device for a warp knitting machine according to claim 2, wherein yarn breakage is detected by abnormal fluctuations in the duty ratio of the binarization circuit. (4) The binarization circuit binarizes the modulation signal using a threshold value formed based on a pseudo DC component of the modulation signal. (5) The binarization circuit outputs a series of pulses having different duty ratios during one cycle period, and the discrimination means individually compares each pulse with a different standard duty ratio, and determines the duty ratio. A yarn breakage detection device for a warp knitting machine according to claim 3, which detects abnormal fluctuations in ratio.