JPH0679637B2 - Lower thread remaining amount detector for sewing machine - Google Patents

Description

The present invention relates to a bobbin thread remaining amount detecting device for a sewing machine, and more particularly, to a bobbin accompanying a certain amount of bobbin thread feeding when a thread cutting operation is performed. The present invention relates to a lower thread remaining amount detecting device for a sewing machine that detects the remaining amount of the lower thread by comparing the rotational state of the lower thread with a predetermined condition.

[Prior Art] In recent years, sewing machines that realize various automation functions by applying electronic control technology have become widespread in various fields. For example, a lower thread remaining amount detecting device used for a lock stitch sewing machine that forms a stitch using an upper thread and a lower thread is also developed for the purpose of the above-mentioned automation function.

In a lockstitch sewing machine, the upper thread is normally provided outside the sewing machine arm or the like by being wound into a relatively large spool.
Therefore, the upper thread remaining amount can be easily detected visually by the operator of the sewing machine. On the other hand, the bobbin thread is wound around a bobbin in the thread ring catcher housed on the lower surface of the sewing machine table. The bobbin winding amount is considerably smaller than the upper thread winding amount. If this lower thread is lost during the sewing operation, the lock stitch will not be formed and a defective product will be produced in the workpiece. For this reason, the sewing machine operator must frequently check the remaining amount of the lower thread during the sewing operation. However, if you try to confirm the remaining amount of bobbin thread with certainty, for example, visually, the operation of the sewing machine is stopped and the sliding plate is opened,
The complicated work of removing the bobbin from the thread catcher and confirming it was necessary.

By the way, the above-mentioned method for checking the remaining amount of the bobbin thread brings about a remarkable decrease in the sewing work efficiency. Therefore, various types of bobbin thread remaining amount detecting methods or bobbin thread remaining amount detecting devices have been conventionally developed. For example, (a) a bobbin shaft cylinder is provided with an illuminator and a light receiver for the purpose of detecting the bobbin thread shortly before it runs out. A device for continuously detecting, by an optical means, that a thread is likely to be lost, "Bobbin lower thread remaining amount detecting device" of Japanese Patent Publication No. 54-39788, (b) Wound on bobbin Just before the bobbin thread is exhausted, a movable flange is provided on one of both flanges of the bobbin for the purpose of warning the operator that the remaining amount has decreased, and the bobbin is loaded with the hook. And "the lower thread consumption detecting device of the sewing machine" of Japanese Patent Publication No. 56-42959, which is configured to notify visually based on the detection of an increase in the distance between the movable flange and the movable flange. A bobbin thread longer than the required length for continuous sewing For the purpose of detecting and, upon winding the lower thread to a bobbin, a continuous predetermined slack portion positions Tsu more long intervals required for sewing certain number needle from the winding start end provided,
A device configured to detect that the bobbin has temporarily stopped rotating due to the slack portion.
Japanese Unexamined Patent Publication No. 74, "Method and apparatus for detecting remaining amount of lower thread of sewing machine" has been proposed.

[Problems to be Solved by the Invention] The following problem exists in the lower thread remaining amount detecting device of the sewing machine as the prior art. That is, (1) a bobbin,
Alternatively, the thread loop catcher such as the bobbin case needs a mechanical modification, the structure becomes complicated, the cost of manufacturing and repairing the device increases, and the reliability decreases. .

(2) Further, an additional step such as providing slack in the step of winding the bobbin around the bobbin occurs, which may increase the number of sewing steps.

(3) Further, during high-speed operation of the sewing machine, the main shaft of the sewing machine rotates at, for example, 4000 to 5000 [rpm], and the thread catcher containing the bobbin generally rotates at twice the rotational speed of the main shaft. Therefore, even if the lower thread remaining amount of the bobbin is detected by, for example, a non-contact method, it is difficult to maintain the detection accuracy at a practical level because the thread catcher is rotating at a high speed. There was also a problem.

(4) On the other hand, in the modern sewing industry, high-mix low-volume production is required. Therefore, different types of workpieces are frequently replaced with different bobbin threads having different thread characteristics, such as thickness. There are many cases where it is used. Therefore, when performing the detection / determination of the lower thread remaining amount, various characteristics of the lower thread,
For example, it is necessary to set a reference value corresponding to the thickness and the like and detect the lower thread remaining amount based on the reference value. However, there is also a problem that it is difficult to detect the corresponding remaining amount of the bobbin thread when the bobbin thread having various characteristics as described above is frequently replaced and used.

Therefore, the present invention has been made for the purpose of solving each of the above problems. That is, the lower thread remaining amount detecting device for the sewing machine, which improves the accuracy and reliability of the lower thread remaining amount detection, shortens the sewing work process, and responds to the working mode in which the lower thread of various characteristics is replaced and sewn. Is provided.

Structure of the Invention [Means for Solving the Problems] In order to solve the above problems and achieve the object of the invention, the present invention has a structure as shown in FIG. Figure 1 shows
It is a basic block diagram which illustrated the basic structure of this invention notionally. According to the present invention, as shown in FIG. 1, a thread trimming signal generating means M1 for generating a thread trimming signal based on an instruction from an operator and a predetermined amount of the bobbin thread wound around a bobbin M2 according to the thread trimming signal are fed out. A bobbin thread remaining amount detecting device provided with a thread cutting means M3 for cutting, and a rotation state detecting means M4 for detecting a rotation state of the bobbin M2 accompanying the feeding of a fixed amount of the bobbin thread, The rotation of the bobbin M2 detected by the rotation state detecting means M4 when it is determined that the thread cutting means M3 is performing the thread cutting operation based on the thread cutting signal from the thread cutting signal generating means M1. A lower thread remaining amount detecting device for a sewing machine, comprising: a determination means M5 for outputting the determination result when it is determined that the state corresponds to a predetermined condition determined based on the lower thread remaining amount. Is the gist.

Here, the thread cutting signal generating means M1 is for transmitting a command for starting a thread cutting operation based on an operation instruction to the thread cutting means M3 and the judging means M5 as a thread cutting signal. For example, a thread cutting signal such as a pulse signal may be generated based on the pedal operation of the operator when the predetermined needle position is stopped. Alternatively, the operation switch of the sewing machine may be set in advance so that the signal is normally at a low level and a thread trimming signal that becomes a high level is generated when a predetermined condition is detected, for example, when the edge of the fabric is detected. Good. In such a case, the operator
There is also an advantage that it is not necessary to operate a pedal or the like.

The thread trimming means M3 is for cutting out the upper thread and the lower thread by a fixed amount when a command is given from the thread trimming signal generating means M1. For example, a moving blade provided near the thread ring catcher, a fixed blade provided to face the moving blade,
It may be configured to include a power source that drives the movable blade and a transmission mechanism that transmits the power to the movable blade. Here, the movable blade may be rotatable around the thread catcher, or may be movable parallel to the needle plate. Further, the power source may be one that moves at a constant speed, for example, a lower shaft that rotates at a constant speed, or a dedicated power source such as an air cylinder that moves at a constant speed. .
For example, when a dedicated power source is used, there is an advantage that the transmission mechanism can be simply configured. further,
The transmission mechanism may be, for example, a cam and a link mechanism, and may transmit the rotational movement of the lower shaft by an electromagnetic solenoid or the like.

The rotation state detecting means M4 means the bobbin that rotates in response to a certain amount of the lower thread being fed along with the thread cutting operation when the thread cutting operation is being performed by the thread cutting means M3.
The rotation state of M2 is detected. For example, an optical detection system can be configured by a pair of a light emitting element and a light receiving element, and a reflecting surface provided on the flange portion of the bobbin M2 having optical marks at equal intervals. Then, the signal based on the reflected light from the reflecting surface of the bobbin M2 is detected,
The rotation speed of the bobbin M2 may be calculated based on the signal. Further, the rotation angle of the bobbin M2 may be detected by a similar method. In this case, there is an advantage that it is not necessary to calculate the rotation speed.

Here, the optical mark of the bobbin M2 may be, for example, a reflection mark in which a substance having a reflectance higher than that of the flange portion of the bobbin is applied at equal intervals. Further, it is also possible to attach, for example, a black seal having a lower reflectance than the flange portion of the bobbin M2 at equal intervals. Further, it may be slits provided at equal intervals on the flange portion of the bobbin. In such a case, there is an advantage that it is possible to prevent erroneous detection due to dirt on the bobbin flange portion, disappearance of the mark portion, or the like.

Further, the rotation state detecting means M4 is not limited to the above-mentioned optical system, for example, as a magnetic detection system in which the equally spaced protrusions provided on the flange portion of the bobbin M2 and magnetic heads are provided at positions corresponding to the protrusions. Good. In such a case, there is an advantage that erroneous detection due to the ambient light irradiation can be prevented.

The determining means M5 is a fixed amount of the bobbin thread obtained from the rotation state detecting means M4 when it is determined by the thread cutting signal from the thread cutting signal generating means M1 that the thread cutting operation is being performed. The rotation state of the bobbin M2 caused by the extension is compared with a predetermined condition, and when it is determined that the predetermined condition is satisfied, the determination result is output. For example, the rotational speed of the bobbin M2 is realized as a logical operation circuit configured with a microprocessor and peripheral elements and input / output circuits, and the rotational speed of the bobbin M2 is equal to or higher than a predetermined rotational speed determined based on the remaining amount of the bobbin thread according to a prestored processing procedure. In this case, a warning may be given to the operator or the sewing machine may be held in a stopped state. In addition, for example, the bobbin M2 at the time of delivering a certain amount of the bobbin thread accompanying the thread cutting operation
If the rotation angle of is greater than or equal to the predetermined rotation angle determined based on the remaining amount of bobbin thread, give a warning to the operator, or
The sewing machine may be held in a stopped state.

Further, the determination means M5 is not necessarily limited to a logic circuit using a microprocessor, for example, is configured by an analog circuit, the rotation speed of the bobbin M2 is converted to a voltage by the F / V converter, the voltage May be compared with a predetermined voltage based on the remaining amount of the bobbin thread, and the result of the determination may be output to give a warning to the operator.

[Operation] The bobbin thread remaining amount detecting device of the sewing machine of the present invention having the above-described configuration operates as follows. That is, as shown in FIG. 1, the thread trimming signal generating means M1 outputs a thread trimming signal to the thread trimming means M3 and the judging means M5 based on an instruction from the operator. Then, the thread cutting means M3 pays out a certain amount of the bobbin thread wound on the bobbin M2 based on the thread cutting signal, and performs the bobbin thread cutting operation. The bobbin M2 rotates as the bobbin thread is fed out by a certain amount. At this time, the rotation state detecting means M4 detects the rotation state of the bobbin M2 and outputs the result to the determining means M5. The judging means M5 rotates the bobbin M2 detected by the rotation state detecting means M4 when it is judged by the thread cutting signal from the thread cutting signal generating means M1 that the thread cutting operation is being performed. It is determined whether or not the state corresponds to a predetermined condition determined based on the lower thread remaining amount. The predetermined condition is, for example, that the rotation state detecting means M4 is the bobbin M2.
When the number of rotations of the bobbin M2 is detected, the number of rotations is a predetermined number of rotations based on the remaining amount of the bobbin thread. Is a predetermined rotation angle based on the remaining amount of lower thread.

Here, the lower thread remaining amount and the rotating state of the bobbin M2 have the following relationship. In other words, there is reproducibility in the unwinding of the bobbin thread that accompanies the thread cutting operation, and when the bobbin thread remaining amount is large, the bobbin M2 has a relatively large bobbin thread winding diameter and a long circumference. The number of rotations or the rotation angle of the bobbin M2 is small with respect to the yarn feeding. On the other hand, when the remaining amount of the bobbin thread is small, the bobbin M2 has a small bobbin thread diameter and a short circumference, and therefore, the bobbin M2 is not able to be fed to the bobbin M2 when a certain amount of bobbin thread is fed.
The rotation speed or rotation angle of is large.

When the judging means M5 judges that the rotation state of the bobbin M2 satisfies the above-mentioned predetermined condition, the judging means M5 outputs the judgment result. Here, outputting the determination result means, for example, a case where a warning is given to the operator, the sewing machine is held in a stopped state, or a plurality of sewing machines are centrally managed by a host control device. First, an abnormal signal is output to the upper control device. As described above, the technical problem of the present invention is solved.

[Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a bobbin thread remaining amount detecting device of the sewing machine in the first embodiment of the present invention. In the figure, a lockstitch automatic thread trimmer sewing machine 1 has a main shaft (not shown) provided inside an arm 1b mounted on a table 1a, and
The direct current motor 2 disposed on the lower surface of 1a is rotationally driven via a belt 1c and a pulley (not shown). Then, the stitch forming mechanism operates in conjunction with the rotation of the main shaft (not shown). That is, the needle 1e attached to the needle bar 1d is connected to the arm 1b.
The needle bar mechanism (not shown) provided inside is reciprocally moved up and down, and the feed mechanism (not shown) is interlocked. A thread ring catcher 3 is attached to the tip of a lower shaft 1f that is provided on the lower surface of the table 1a and is connected to the upper shaft by a vertical shaft (not shown). ,
Full rotation is performed twice for one reciprocating movement of the needle 1e to form a lock stitch. The thread catcher 3 has a bobbin 4 housed therein. A thread cutting mechanism 5 is arranged near the thread ring catcher 3, and the thread cutting mechanism 5 receives power from the lower shaft 1f by the operation of a thread cutting solenoid 5k. Operate. Further, a photodetector 6 is arranged near the end surface of the thread catcher 3 opposite to the lower shaft 1f, and the photodetector 6 has a bobbin sensor light source 6c and a bobbin sensor 6e.

On the other hand, on the belt 1c side of the arm 1b, the needle position detector 7
Is provided. The needle position detector 7 is an on-needle position sensor including a permanent magnet piece that rotates in conjunction with a main shaft (not shown) and a hall element provided facing the permanent magnet piece.
7a and the needle position sensor 7b. The needle position detector 7 detects the needle up position and needle down position of the needle 1e, and also detects the rotation speed of a spindle (not shown).

An operation panel 8 is provided on the front surface of the arm 1b. The operation panel 8 has a dial type lower thread remaining amount setting switch 8a for setting a lower thread remaining amount which will be described later and, as will be described later. A warning lamp 8b is provided which lights up in red and warns the operator when the remaining amount of the bobbin thread becomes less than a set value.

On the other hand, a support shaft 1h is fixed to the leg portion 1g of the table 1a, and a pedal 9 is supported on the support shaft 1h so as to be capable of three positions of front depression, release and rear depression. The pedal 9 is connected to a pedal switch 9b provided on the lower surface of the table 1a via a connecting rod 9a. Note that the front depression of the pedal 9 is for instructing the forward lock stitch operation, and the rotation speed of the main spindle is, for example, 200 to 5000 corresponding to the depression amount.
Varies within the [rpm] range. Further, the release of the bedal 9 commands the stop of the needle down position of the needle 1e, and the rearward depression of the pedal 9 commands the thread trimming operation by the thread trimming mechanism 5. In this case, the rotation speed of the spindle. Is, for example, 200
It is about [rpm], so the rotation speed of the lower shaft 1f is 400.
It becomes [rpm].

The output signals of the above sensors and switches are input to the electronic control circuit 10 arranged below the table 1a. Then, the electronic control circuit 10 controls the drive of each of the above mechanisms.

Next, the structures of the thread loop catcher 3 and the peripheral mechanism portion of the photodetector 6 will be described with reference to FIGS. 3 and 4. FIG. 3 is a partial cross-sectional view of the thread loop catcher 3 and the peripheral mechanism portion of the photodetector 6.

In the same figure, below the needle 1e described above, above the table
The needle plate 1i provided on the bed of 1a is laid. The thread catcher 3 cooperates with the vertical reciprocating motion of the needle 1e to form a lock stitch. The thread loop catcher 3 is fixed to the lower shaft 1f, makes full rotation twice for one reciprocating movement of the needle 1e, and catches the thread loop of the upper thread incidental to the needle 1e. An outer hook 3a provided with a sword tip, and an inner hook which is supported inside the outer hook 3a and is restrained from rotating with the rotation of the outer hook 3a by an inner hook stopper (not shown) fixed to the lower surface of the bed. 3b,
The bobbin case 3c is supported in the inner hook 3b, and the bobbin case 3c is detachably inserted into the inner hook 3b. In addition, on the front surface located on the opposite side to the lower shaft 1f of the bobbin case 3c,
An opening 3d is provided.

The bobbin 4 is rotatably accommodated in the bobbin case, and the bobbin thread 11 is wound around the outer peripheral surface of the bobbin shaft tube 4a of the bobbin 4.

Here, the structure of the side surface of the bobbin 4 on the side facing the opening 3d of the bobbin case 3c will be described with reference to FIG. FIG. 4 is a side view of the bobbin 4. In the figure, the bobbin 4 has a bobbin shaft tube 4a in which the bobbin case 3c has a shaft inserted therein and a bobbin thread 11 is wound around the outer peripheral surface of the bobbin case 3c. It has a plate-shaped bobbin flange 4b. The bobbin flange 4b is made of a rustproof iron plate or aluminum plate. Then, as shown in FIG. 4, optical marks 4c are drawn on the surface of the bobbin case 3c on the side facing the opening 3d at equal intervals with a material having a higher reflectance than the bobbin flange 4b. There is. The optical mark 4c
On the contrary, if the condition of equal spacing is satisfied, conversely, bobbin flange 4b
It may be drawn with a paint having a lower reflectance than black light, for example, which does not reflect black light, and may be engraved as slits at equal intervals.

As shown in FIG. 3, a bracket 6a is provided near the needle plate 1i in front of the opening 3d of the bobbin case 3c on the side opposite to the lower shaft 1f of the thread catcher 3. A sliding board
It is fixed at 1k. The photodetector 6 is provided on the bracket 6a. Here, since the photodetector 6 is fixed to the sliding plate 1k, it moves together with the sliding plate 1k. Therefore, when the bobbin 4 is taken out, the photodetector 6
There is no conflict with. Further, when fixing the photodetector 6 to a rib or the like under the bed, a mechanism for retreating along with the opening of the sliding plate 1k is additionally provided to avoid a conflict when the bobbin 4 is taken out. be able to.

The photodetector 6 is composed of a light source and a sensor. The light source is composed of a black resin rectangular parallelepiped light source housing 6b whose one end face is open, and a bobbin sensor light source 6c formed of a light emitting diode housed inside the light source housing 6b. On the other hand, the sensor includes a sensor housing 6d, which is also made of a black resin and has a rectangular parallelepiped shape and one end surface of which is open, and a bobbin sensor 6e formed of a phototransistor housed inside the sensor housing 6d. The slit 6f is provided in the opening of the sensor housing 6d.
A black resin slit plate 6g provided at the center is disposed to prevent disturbance light from entering the bobbin sensor 6e. Then, the light emitted from the bobbin sensor light source 6c passes through the opening 3d of the bobbin case 3c, illuminates a part of the bobbin flange 4b, and the light reflected by the optical mark 4c of the bobbin flange 4b is , The above bobbin case again
The light passes through the opening 3d of 3c, passes through the slit 6f of the slit plate 6g of the sensor housing 6d, and is received by the bobbin sensor 6e. Here, the slits 6f of the slit plate 6g are provided by selecting an angle at which only the reflected light from the bobbin flange 4b enters, and prevent disturbance light from entering. Note that, for example, a light emitting diode that emits infrared light may be used for the bobbin sensor light source 6c, and a photoelectric conversion element having the highest sensitivity at the wavelength corresponding to the above light in the infrared region may be used for the bobbin sensor 6e. Alternatively, the bobbin sensor light source 6c may be used with a light emitting element that emits light having a frequency with a specific modulation, and the bobbin sensor 6e may be used with a photoelectric conversion element that demodulates light with the above frequency. In such a case, the slit plate 6g of the sensor housing 6d
It is possible to prevent ambient light without providing the. The bobbin sensor 6e is a light path as described above, the voltage of the output signal rises when the reflected light from the optical mark 4c of the bobbin flange 4b is received, while the output signal is increased when the reflected light is not received. Outputs an analog signal that lowers the voltage.

Next, regarding the structure of the thread trimming mechanism 5, FIG.
Description will be given based on each figure. Further, the thread cutting operation of the thread cutting mechanism 5 will be described with reference to FIGS. 7 and 8.

FIG. 5 is a side view of the thread trimming mechanism 5, in which the broken line shows the stopped state of each member and the solid line shows the operating state of each member. FIG. 6 is a front view of the thread cutting mechanism in an operating state.

As shown in FIGS. 5 and 6, the thread cutting mechanism 5
Is a movable blade 5a that rotates between the needle plate 1i and a thread ring catcher (not shown), a fixed blade 5b fixed at a position corresponding to the movable blade 5a, and a fixed surface of the fixed blade 5b. Threading 5c
The thread cutting is performed in cooperation with and. Also, the moving blade 5a
As a power transmission mechanism to the thread trimmer holder 5d, bifurcated shaft 5e,
Thread trimming cam lever set 5f, roller shaft 5g, cam lever return spring
5h, thread trimming lever 5i, thread trimming rod 5j, thread trimming solenoid
5k is provided. The driving force is given from the thread cutting cam 5l provided on the lower shaft 1f.

When the thread trimming mechanism 5 is in the stopped state,
It is at the position indicated by the broken line in FIG. Further, as shown in FIG. 6, the thread trimming cam lever set 5f includes a cam lever return spring 5h.
Is urged in the direction indicated by arrow A. For this reason,
Since the roller shaft 5g and the thread cutting cam 5l do not engage with each other, the movement of the lower shaft 1f is not transmitted to the thread cutting mechanism 5.

On the other hand, when the operator releases the pedal 9 after the lock stitching operation to stop the sewing machine once at the needle lower position and then depresses the pedal 9 backward, the thread trimming operation is started. In this case, first, the electronic control circuit 10 drives the DC motor 2 to about 200 [rpm].
Rotate at a constant speed with a degree. Then, the thread trimming solenoid 5k is excited. Then, the thread trimming cam lever set 5f moves in the direction indicated by arrow B in FIG. 6 against the bias of the cam lever return spring 5h. Along with this, the roller shaft 5g meshes with the thread cutting cam 5l rotating together with the lower shaft 1f. Then, the power is transmitted to the thread cutting mechanism 5. In this case, when the thread trimming cam 5l pushes up the roller shaft 5g, the movement of the thread trimming cam lever 5e, the thread trimming lever 5i, the thread trimming connecting rod
5j is transmitted to the thread trimming holder 5d. As a result, as shown in FIG. 5, the thread trimming holder 5d is moved from the position indicated by the broken line to
It moves in the direction indicated by arrow C and reaches the position indicated by the solid line.
Along with this, the movable blade 5a moves from the position indicated by the broken line in the direction indicated by the arrow D to reach the position indicated by the solid line. Here, the movable blade 5a overlaps with the fixed blade 5b, and thread cutting is performed.

Next, based on FIG. 7 and FIG. 8, a certain amount of bobbin thread feeding associated with the thread cutting operation will be described. Figure 7 shows
It is explanatory drawing which shows the state at the time of cutting in thread cutting operation,
FIG. 8 is an enlarged view of the main part of FIG. 7 with the fixed blade 5b removed.

As shown in FIG. 7, the needle 1e and the thread ring catcher 3 cooperate with each other to form a lock stitch 13 by the lower thread 11 and the upper thread 12.

When the thread cutting operation is started, the movable blade 5a moves in the direction indicated by the arrow E with the constant speed rotation of the lower shaft 1f (not shown).
On the other hand, the outer shuttle 3a of the thread catcher 3 makes a full rotation in the direction indicated by arrow F. At this time, the upper thread 12 captured by the sword tip (not shown) of the outer hook 3a passes through the inner hook 3b. And the outer pot
The upper thread 12 and the lower thread 11 which are thread-divided by the sword tip of 3a form a triangular loop as shown between the needle thread and the needle hole 1j.
The movable blade 5a enters into this triangular loop and performs thread separation of the lower thread 11 and the upper thread 12. As enlarged and shown in FIG. 8, the movable blade 5a moves at a constant speed in a direction indicated by an arrow G. Then, the lower thread 11 and the upper thread 12 are gradually spread by the end flared shape of the movable blade 5a and the thread separation 5c. As the moving blade 5a moves at a constant speed, the lower thread 11
And a certain amount of the upper thread 12 is secured. Then, when the movable blade 5a reaches a predetermined position, thread cutting is performed.

Next, the configuration of the electronic control circuit 10 will be described with reference to FIG.

The electronic control circuit 10 inputs and calculates each data or command output from each of the above-mentioned sensors and switches according to a control program, and performs a process for controlling the above-mentioned various devices. A central processing unit (hereinafter simply referred to as CPU). 10a, a read-only memory (hereinafter simply referred to as a ROM) 10b in which the above control program and initial data are stored in advance, various data input to the electronic control circuit 10 and data necessary for commands and arithmetic control are temporarily stored. Random access memory (hereinafter simply referred to as RAM) 10c that is stored in memory is provided.

Further, the electronic control circuit 10 includes a pedal switch 9 described above.
b, output signal buffer 1 from bobbin thread remaining amount setting switch 8a
0d and 10e, a multiplexer 10f that selectively outputs the output signals of the switches to the CPU 10a, and an A / D converter 10g that converts an analog signal into a digital signal are provided. Then, the buffer 10h for the output signal of the bobbin sensor 6e described above, a comparator 10i that compares the output voltage of the bobbin sensor 6e with a predetermined voltage and outputs a signal when the voltage is a predetermined voltage or more, the above-mentioned needle position sensor 7a, A waveform shaping circuit 10j that shapes the waveform of each output signal of the needle position sensor 7b is provided.

Further, the buffers 10d and 10e, the multiplexer 10
f, the A / D converter 10g, the comparator 10i, and the waveform shaping circuit 10j to send the signals of the above switches and sensors to the CPU 10a and the multiplexer from the CPU 10a.
It also has an input / output port 10k that outputs control signals to 10f and A / D converter 10g.

Further, the electronic control circuit 10 includes the above-described DC motor 2, thread cutting solenoid 5k, bobbin sensor light source 6c, and warning light 8b.
Drive circuits 10l, 10m, 10
n, 10p, each of the drive circuits 10l, 10m, 10
It has an output port 10r for outputting a control signal to n and 10p.

Then, the bus line 10s serving as a passage for control signals and data between the above-mentioned elements, the CPU 10a, the ROM 10b, and the RAM 10c.
It also has a clock circuit 10t for sending a clock signal which becomes a control timing at a predetermined interval, and a self-propelled timer 10u for counting time according to a set / reset command of the CPU 10a.

Next, the processing executed by the electronic control circuit 10 will be described based on the flowcharts shown in FIGS. 10 and 11. FIG. 10 is a flowchart showing the main control processing of the lockstitch automatic thread trimming sewing machine 1, and FIG. 11 shows the details of the thread trimming operation and the bobbin thread remaining amount detection processing of the processing shown in FIG. It is a flowchart. In the following description, the three-digit number in parentheses indicates the step number of each process shown in FIGS. 10 and 11.

First, the main control process shown in FIG. 10 will be described. When the power of the lockstitch automatic thread trimmer sewing machine 1 is turned on, the electronic control circuit 10
By this, this processing is started and initialization processing is performed (100). That is, memory clear, flag reset,
Timer reset, setting of each initial data, etc. are performed. Next, the bobbin thread remaining amount setting switch 8a on the operation panel 8
From this, the set value used to determine the remaining amount of lower thread is detected.
(120). This set value is set in advance by the operator using the bobbin thread remaining amount setting switch 8a. The amount to be set may be the length of the lower thread remaining amount, or the bobbin 4
It may be the number of signals detected by the bobbin sensor 6e when is rotated. Next, from the lower thread remaining amount set value detected by the lower thread remaining amount setting switch 8a detected in step 120, the number of rotations of the bobbin 4 corresponding to the set value is calculated (140). Then, this rotation speed is used as the reference rotation speed N0 in the RAM.
It is stored in a predetermined area within 10c.

Next, a lock stitch process is performed (160). Here, the state of the pedal 9 is detected from the pedal switch 9b, and the corresponding operation is performed. That is, when the pedal 9 is stepped forward, the main shaft is rotated in the range of 200 to 5000 [rpm] according to the stepped amount of the pedal 9,
The DC motor 2 is controlled. And the needle that works with the spindle
A lock stitch is formed by the cooperation of 1e and the thread ring catcher 3 connected to the lower shaft. Further, when the position of the pedal 9 changes from the front depression to the release position, the following control is performed by the electronic control circuit 10. That is, the DC motor 2 is controlled so that the rotation speed of the main shaft is about 200 [rpm]. Then, when the needle position sensor 7b of the needle position detector 7 outputs a detection signal, the rotation of the spindle is stopped by the electromagnetic brake. In this way, it stops at the needle stop position. Then, it is determined whether there is a thread cutting instruction from the operator (180). If this condition is not met, the process returns to step 120. On the other hand, when the condition of step 180 is satisfied, that is, when the pedal 9 is stepped backward and the thread cutting instruction is input, step 200
Proceed to. Here, a thread trimming operation, which will be described later, and a bobbin thread remaining amount detecting process which is executed in association therewith are performed (20
0). Then, this process ends. It should be noted that this main control processing is repeatedly executed as appropriate thereafter.

Here, details of the thread cutting operation and the bobbin thread remaining amount detection processing will be described with reference to the flowchart of FIG.

First, the electronic control circuit 10 performs thread cutting operation start processing (205). That is, from the output port 10r to the drive circuits 10l, 1
The control signal is output at 0m. And the DC motor 2 is 20
It is controlled to a constant speed rotation state of about 0 [rpm]. Also,
The thread trimming solenoid 5k is excited. As a result, the lower shaft 1f
Power is transmitted from the thread cutting mechanism 5 to the thread cutting mechanism 5 to operate. Next, RA for counting the number N of bobbin sensor signals
The counter provided in M10c is cleared (210).
Further, the CPU 10a resets the timer 10u (21
Five). Next, the CPU 10a reads the count value of the self-propelled timer 10u at any time, and determines whether or not the delay time Td has elapsed after the start of the thread cutting operation (220). Then, it waits until the delay time Td elapses. This is because the bobbin thread 11 is fed out by the moving blade 5a after the delay time Td has elapsed after the thread cutting operation was started. When the delay time Td has elapsed, the CPU 10a resets the timer 10u again (225). Then, the bobbin sensor light source 6c is turned on and the bobbin sensor 6e is activated (230). At this stage, the bobbin 4 starts to rotate as the lower thread 11 is paid out by the moving blade 5a. Next, the bobbin sensor 6e causes the rotating bobbin 4
It is determined whether or not the reflected light from is detected (235). When this condition is met, that is, when the bobbin sensor 6e detects the reflected light from the bobbin 4, the bobbin 4
If it is confirmed that the rotation has occurred, the process proceeds to step 240. Then, in order to calculate the rotation speed of the bobbin 4, the number N of bobbin sensor signals is counted up, and the process proceeds to step 245. On the other hand, when the condition of step 235 is not satisfied, that is, when the bobbin sensor 6e cannot detect the reflected light from the bobbin 4 and the rotation of the bobbin 4 cannot be confirmed, the process proceeds to step 245. Here, CPU 10a is timer 10u
The count value of is detected and it is determined whether the measurement time T1 has elapsed (245). If this condition is not met, the process returns to step 235, and the process of detecting the rotation of the bobbin 4 is repeated again. On the other hand, when the condition of step 245 is satisfied, that is, when the measurement time T1 has elapsed after the measurement is started, the process proceeds to step 250. Here, the bobbin sensor light source 6c is turned off, and the bobbin sensor 6e
The operation of is also completed (250). Then, it is determined whether the needle up position sensor 7a of the needle position detector 7 has detected the needle up position (260). Here, it waits until the needle up position is detected. When the needle up position is detected, the process proceeds to step 265.
Here, the thread cutting operation end processing is performed (265). That is, the electronic control circuit 10 uses the drive circuit 1 from the output port 10r.
Output control signal to 0l and 10m. As a result, the DC motor 2 is stopped and the exciting current of the thread cutting solenoid 5k is cut off. Next, based on the number N of bobbin sensor signals counted in step 240 and the measurement time T1, the rotation speed Ne of the bobbin 4 is calculated by the equation (1) (27).
0).

Ne = N / T1 (1) Next, the rotation speed Ne of the bobbin 4 calculated in the above step 270.
However, it is determined whether or not it exceeds the reference rotation speed N0 calculated in step 140 (275). Here, when the remaining amount of the bobbin thread wound around the bobbin 4 is sufficiently large and exceeds the set amount, the winding diameter of the thread of the bobbin 4 is large, and therefore the circumference thereof is also long. Therefore, even if a certain amount of bobbin thread is fed along with the thread trimming operation, the rotation speed of the bobbin 4 is equal to the reference rotation speed N0.
Lower. On the other hand, when the bobbin thread is exhausted and the remaining amount of the bobbin thread is less than the set amount, the winding diameter of the thread of the bobbin 4 becomes small, and the circumference thereof also becomes short. Therefore, when a certain amount of bobbin thread is delivered, the rotation speed of the bobbin 4 becomes higher than the reference rotation speed N0.

When the condition of step 275 is satisfied, that is, when the lower thread remaining amount is less than the set amount, the process proceeds to step 280.
Here, the electronic control circuit 10 turns on the warning lamp 8b to warn the operator that the remaining amount of the bobbin thread is small (280). Then, the electronic control circuit 10 keeps the sewing machine in a stopped state while keeping the DC motor 2 inoperative, thereby preventing malfunction (285). Then, the thread cutting operation and the bobbin thread remaining amount detection processing are ended.

On the other hand, when the condition of step 275 is not satisfied, that is, when the lower bobbin thread remaining amount is larger than the set amount, the thread trimming operation and the lower bobbin thread remaining amount detecting process are ended as they are.

Note that the warning light 8b in step 280 is turned on, and step 2
The sewing machine stop process of 85 is canceled by the manual recovery operation of the operator such as turning on the main power again, and the sewing machine returns to the normal state.

Next, an example of the control timing performed by the electronic control circuit 10 will be described with reference to FIG.

In the figure, when the needle down position sensor 7b of the needle position detector 7 outputs a detection signal and the sewing machine is stopped at the needle down position, the operator depresses the pedal 9 rearward so that the thread trimming signal Changes from the "OFF" state to the "ON" state. This time is t1. Then, from this time t1, the delay time Td
At time t2 when only the time elapses, the electronic control circuit 10 performs the following control. That is, in response to step 230 described above, the bobbin sensor light source 6c is turned on (ON), and the bobbin sensor detection control signal is changed from “OFF” to “O”.
"N" state. Then, the bobbin sensor 6e can detect a signal corresponding to the reflected light. Above bobbin sensor
The square wave signal that is the output signal of 6e and has passed through the comparator 10i is input to the electronic control circuit 10 from time t3. Then, from time t2, measurement time t1 elapses time t4
Up to the above, detection and counting of the above signals are performed. This corresponds to the steps (235, 240, 245) described above. Then, corresponding to step 250 described above, at time t4 when the measurement time T1 ends, both the bobbin sensor light source 6c and the bobbin sensor detection control signal are set to the “OFF” state. Next, the electronic control circuit 10 waits until the thread trimming signal becomes the “OFF” state, corresponding to step 260 described above. At time t5 when the needle up position sensor 7a detects the needle up position,
The thread trimming signal is in the "OFF" state. Then, the electronic control circuit 10 calculates the rotation speed Ne of the bobbin 4 according to the above-described formula (1) based on the number of signals N counted within the measurement time T1. This corresponds to step 270 described above. When it is determined that the rotation speed Ne of the bobbin 4 exceeds the preset reference rotation speed N0, that is, it is determined that the bobbin thread remaining amount is less than the set amount and the rotation speed of the bobbin 4 has increased. If so, the following control is performed. First, at a time t6, the control signal of the warning light 8b is turned on. DC motor 2 at the same time
The control signal of is turned off. Along with this, the warning lamp 8b is turned on to warn the operator that the bobbin thread remaining amount is less than the set amount. Then, the DC motor 2 is stopped, and malfunction of the sewing machine is prevented.

In the first embodiment, the needle down position sensor 7b, the pedal switch 9b, the electronic control circuit 10, and the processing (205) executed by the electronic control circuit 10 correspond to the thread cutting signal generating means M1. Further, the thread trimming mechanism 5, the electronic control circuit 10, and the processes (205, 260, 26) executed by the electronic control circuit 10 are executed.
5) corresponds to the thread cutting means M3. Furthermore, the photodetector 6, the electronic control circuit 10, and the processing (210, 215, 220, 225, 230, 235, 240, 245, executed by the electronic control circuit 10
250, 270) corresponds to the rotation state detecting means M4. And
The warning lamp 8b, the electronic control circuit 10, and the processes (275, 280, 285) executed by the electronic control circuit 10 correspond to the determination means M5.

According to the first embodiment of the present invention described above, when the lockstitch automatic thread trimming sewing machine 1 performs the thread trimming operation, the moving blade 5a of the thread trimming mechanism 5 is always constant along with the low speed constant rotation of the lower shaft 1f. Focusing on the fact that the bobbin thread 11 is fed out by a certain amount by moving at a speed, the rotation speed Ne of the bobbin 4 accompanying this is calculated,
When the number of revolutions Ne exceeds a preset reference number of revolutions N0, the warning lamp 8b is turned on and the lockstitch automatic thread trimmer sewing machine 1 is held in a stopped state. Therefore, when the amount of the bobbin thread 11 wound on the bobbin 4 is less than the set amount, the operator can easily know the consumption of the bobbin thread by turning on the warning lamp 8b.

When the bobbin thread 11 is less than the set value, the lockstitch automatic thread trimmer sewing machine 1 is held in a stopped state. It is possible to prevent the occurrence of defects.

Further, since the set value for the lower thread remaining amount determination can be arbitrarily set by the lower thread remaining amount setting switch 8a, it is possible to frequently change and use lower threads having various characteristics such as different thicknesses. It can be handled easily.

In addition to the above effects, there are advantages that rationalization of sewing work, improvement of reliability, and support for small-lot production of a wide variety of products can be achieved.

Furthermore, the bobbin sensor light source is used only when the thread trimming operation is performed.
Since the 6c and the bobbin sensor 6e are energized, the life of both elements can be extended.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings. The difference between the first embodiment and the second embodiment is the following two points. That is, in the first embodiment, as the rotation state of the bobbin 4, the output signal of the bobbin sensor 6e within the measurement time T1 is counted, the rotation speed Ne of the bobbin 4 is calculated as Ne = N / T1, and the rotation speed Ne is calculated. While the lower bobbin thread remaining amount is determined by comparing with the set reference rotational speed N0, in the second embodiment, the output signal of the bobbin sensor 6e is counted as the rotating state of the bobbin 4. The first difference is that the rotation angle of the bobbin 4 is detected and the bobbin thread remaining amount is determined when the rotation angle is equal to or larger than the set rotation angle. Further, in the first embodiment, the lower thread remaining amount reference value is set in advance from the lower thread remaining amount setting switch 8a, whereas in the second embodiment, the lower thread remaining amount reference value is set. Is configured to be set in the teaching process executed by the electronic control circuit 10, which is a second difference.

Device schematic configuration of the second embodiment, and thread ring catcher 3, thread cutting mechanism 5, photodetector 6, needle position detector 7, electronic control circuit
Since the configuration of 10 is the same as that of the first embodiment, the same reference numerals as those used in the respective drawings of the first embodiment are used and the description thereof is omitted.

The processing executed by the electronic control circuit 10 in the second embodiment will be described based on the flowcharts of FIGS. 13, 14, and 15. FIG. 13 shows the main control process performed in the second embodiment, FIG. 14 shows the details of the teaching process during the main control process, and FIG. 15 shows the thread cutting operation during the control process. The details of the bobbin thread remaining amount detection processing will be described. In the following description, the three-digit number in parentheses indicates the step number of each process.

In FIG. 13, when the main control process is started, first,
Initialization processing is performed (300). The content of this process is
This is the same as step 100 of the first embodiment. Next, it is determined whether the teaching is completed (310). If this condition is met, go to step 560. On the other hand, if the condition of step 310 is not met, the process proceeds to step 400. In this step 400, as will be described later,
The rotation angle of the bobbin 4, which serves as a reference for determining the lower thread remaining amount, is stored in the electronic control circuit 10 as the number of signals of the bobbin sensor 6e according to the instruction of the operator. Then, it proceeds to step 560. Here, a lock stitch process having the same contents as in step 160 of the first embodiment is performed. Then, the process proceeds to step 580. Here, the presence or absence of the thread trimming instruction is determined by the same processing as step 180 of the first embodiment (580). If this condition is not met, the process returns to step 310. on the other hand,
If the condition of step 580 is met, the process proceeds to step 600, and the thread cutting operation and the bobbin thread remaining amount detection processing described later are performed (600). Then, the main control process is ended.
It should be noted that this main control processing is repeatedly executed as appropriate thereafter.

Next, the teaching process (400) performed during the main control process will be described in detail with reference to the flowchart of FIG.

Before starting the teaching process, the operator preliminarily winds the bobbin 4 on the bobbin 4 and attaches the bobbin thread to the thread ring catcher 3 as a reference for determining the bobbin thread remaining amount. Then, the teaching process (400) is started. First, the needle down stop process is performed (410). That is, the electronic control circuit 10 rotates the DC motor 2 to reciprocate the needle 1e once, and then drives the main shaft to a position where the needle down position sensor 7b detects the needle down position, and rotates it by an electromagnetic brake. stop. Here, if the operator fixes the end of the needle thread that has passed through the needle 1e when the needle 1e is moved up and down, the bobbin thread is entangled with the needle thread by one reciprocating movement of the needle 1e. To form one seam. In this state, the sewing machine stops at the needle lower position. In this way, the needle down stop process is performed. Then, the process proceeds to step 420. Here, the operation waits until the operator depresses the pedal 9 backward. When the rearward depression of the pedal 9 is made, the routine proceeds to step 425. Here, as the thread cutting operation start processing, the DC motor 2 is rotated at a constant speed and the thread cutting solenoid 5k is excited (425). Next, the counter provided in the RAM 10c for counting the number n of bobbin sensor signals is cleared (430). And the electronic control circuit 10
Turns on the bobbin sensor light source 6c and starts the operation of the bobbin sensor 6e (440). Here, it is determined whether or not a signal from the bobbin sensor 6e associated with the rotation of the bobbin 4 due to the constant amount of lower thread feeding of the thread cutting operation is detected (445). If the above signal is detected, it is determined that the bobbin 4 has been rotated, and the routine proceeds to step 450, where the number n of bobbin sensor signals is counted up.
Then go to step 455. On the other hand, if the signal is not detected, it is determined that the rotation of the bobbin 4 is not confirmed, and the process proceeds to step 455. Here, it is determined whether or not it is at the needle up position based on the presence or absence of the detection signal of the needle up position sensor 7b of the needle position detector 7 (455). If this condition is not met, the process returns to step 445, and the detection / counting of the bobbin sensor signal is repeated again. On the other hand, if the condition of step 455 is met, the process proceeds to step 460.
Here, as the thread cutting operation end processing, the DC motor 2 is stopped and the exciting current to the thread cutting solenoid 5k is cut off (460). Then, the bobbin sensor light source 6c is turned off, and the operation of the bobbin sensor 6e is finished (470).
Next, the number n of bobbin sensor signals counted in step 450 is stored as a reference number n0 in a predetermined area in the RAM 10c (475). The teaching process is performed as described above.

Next, the thread cutting operation and the bobbin thread remaining amount detection processing (600) performed during the main control processing will be described in detail with reference to the flowchart of FIG.

When the control shifts to the thread trimming operation and the bobbin thread remaining amount detection processing (600), steps 625, 630, 640, 645, 650, 655, 66
Each of the processes 0 and 670 is sequentially performed, and a rotation angle of the bobbin 4 corresponding to a certain amount of bobbin thread payout accompanying the thread cutting operation is set as a bobbin sensor signal number n in a counter provided in the RAM 10c. Is counted. The contents of each of these processes are the same as those in each step (4) of the teaching process (400) described above.
25, 430, 440, 445, 450, 455, 460, 470). Therefore, detailed description thereof will be omitted.

Next, in step 680, it is determined whether the number n of bobbin sensor signals counted in step 650 exceeds the reference number n0 stored in step 475 of the teaching process (400) (680). Here, when the remaining amount of the bobbin thread wound on the bobbin 4 is sufficiently large and exceeds the set amount, the winding diameter of the thread of the bobbin 4 is large, and therefore the circumference thereof is relatively long. Therefore, even if a certain amount of bobbin thread is fed along with the thread cutting operation, the rotation angle of the bobbin 4 is small,
The number n of bobbin sensor signals is also smaller than the reference number n0. On the other hand, when the bobbin thread is consumed and the remaining amount is less than the set amount, the winding diameter of the thread of the bobbin 4 becomes small, and therefore the circumference becomes relatively short. Therefore, when a certain amount of bobbin thread is delivered, the rotation angle of the bobbin 4 becomes large, and the number n of bobbin sensor signals also becomes larger than the reference number n0.

When the condition of step 680 is satisfied, that is, when the lower thread remaining amount is less than the set amount, the process proceeds to step 685.
Here, the electronic control circuit 10 turns on the warning lamp 8b to warn the operator that the remaining amount of the bobbin thread is small (685). Then, the electronic control circuit 10 keeps the sewing machine in a stopped state while keeping the DC motor 2 in a stationary state to prevent malfunction (690). Then, the thread cutting operation and the bobbin thread remaining amount detection processing are ended.

On the other hand, when the condition of step 680 is not satisfied, that is, when the lower thread remaining amount is larger than the set amount, the thread trimming operation and the lower thread remaining amount detecting process are ended.

The process (680) of comparing the number n0 of bobbin sensor signals with the reference number n0 is performed next to the process (650) of counting the number n of bobbin sensor signals, and when the condition is satisfied, the warning light 8b is immediately output. The process of turning on (685) is performed,
After the thread trimming operation end process (660), the sewing machine stop process (69
0) can be configured. In this case, the response of the warning is improved.

Also, turn on the warning light 8b in step 685, and step 6
The sewing machine stop processing of 90 is canceled by the operator's manual recovery processing such as turning on the main power again, and the sewing machine returns to the normal state.

Next, an example of the control timing performed by the electronic control circuit 10 will be described with reference to FIG. The timing chart shows the operation after the teaching process (400) is executed.

In the figure, when the needle down position sensor 7b of the needle position detector 7 outputs a detection signal and the sewing machine is stopped at the needle down position, the operator depresses the pedal 9 rearward so that the thread trimming signal Changes from the "OFF" state to the "ON" state. At time t11, the electronic control circuit 10 turns on the bobbin sensor light source 6c (ON) and also changes the bobbin sensor detection control signal from the "OFF" state to the "ON" state, corresponding to step 640 described above. Then, the signal can be detected from the bobbin sensor 6e. Next, at time t13, the signal from the bobbin sensor 6e corresponding to the reflected light from the bobbin 4, which is in the state of passing through the comparator 10i, is detected by the electronic control circuit 10 and counted.
This corresponds to steps 645, 650, 655 described above.
In this example, at time t16, the bobbin sensor 6e
It is assumed that the count value n of the detection signal from is greater than the reference number n0 set in the teaching process. Thus, the rotation angle of the bobbin is continuously detected, but when the needle up position sensor 7a of the needle position detector 7 outputs the detection signal, the thread trimming signal changes from the "ON" state to the "OFF" state. This time is t
It will be 17. After the same time, both the bobbin sensor light source 6c and the bobbin sensor detection control signal are extinguished at time t18 by the electronic control circuit 10 corresponding to step 670 described above (OF
F) or "OFF" state. Then, at time t20, the electronic control circuit 10 turns on the warning lamp control signal to turn on the warning lamp 8b to give a warning to the operator. This corresponds to step 685 described above. At the same time,
The electronic control circuit 10 turns off the DC motor control signal,
The DC motor 2 is stopped and the sewing machine is held in a stopped state to prevent malfunction. This is step 69 described above.
Corresponds to 0.

If the electronic control circuit is configured to determine that the bobbin thread remaining amount becomes equal to or less than the set value at time t16, the warning lamp 8b may be immediately turned on at time t16.

In the second embodiment, the thread cutting mechanism 5, the electronic control circuit 10, and the processing executed by the electronic control circuit 10 (62
5, 655, 660) correspond to the thread cutting means M3. Further, the photodetector 6, the electronic control circuit 10, and the processing (630, 640, 645, 650, 670) executed by the electronic control circuit 10 correspond to the rotation state detecting means M4. Further, the warning lamp 8b, the electronic control circuit 10, and the processing (680, 685, 690) executed by the electronic control circuit 10 correspond to the determination means M5.

In the second embodiment of the present invention, when the lockstitch automatic thread trimming sewing machine 1 carries out the thread trimming operation, the rotation angle of the bobbin 4 accompanying the constant amount of the bobbin thread 11 being fed out is detected as the number of signals of the bobbin sensor 6e. When the rotation angle is equal to or larger than the rotation angle set during the teaching process, the warning light 8b is turned on after the thread trimming operation is completed, and the lockstitch automatic thread trimming sewing machine 1 is held in a stopped state. There is. Therefore, in addition to the effects of the first embodiment, the following effects are produced.

Since the rotation angle of the bobbin 4 can be immediately detected only by detecting and counting the number of output signals of the bobbin sensor 6e,
There is an advantage that it is not necessary to perform calculation when detecting the rotation state of the bobbin 4.

In addition, the setting of the rotation angle of the bobbin 4 based on the remaining amount of lower thread is
Since this is performed by actually teaching the bobbin 4 by winding the bobbin thread and performing a thread cutting operation, it is difficult to quantitatively grasp the relationship between the remaining amount of the bobbin thread and the rotating state of the bobbin 4 in advance. It is possible to accurately detect the remaining amount of the bobbin thread even for the bobbin thread that it has, and the effects of the present invention can be fully brought out.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, CP
Instead of the electronic control circuit 10 mainly composed of the U10a or the like having a microcomputer, it is also possible to use an electronic control circuit 20 having a discrete structure composed of a combination of logic elements as shown in FIG. Is.

As shown in the figure, the needle down position sensor 7b and pedal switch
Both output signals 9b are input to the D-type flip-flop circuit 20a, and the output signal of the needle position sensor 7a is input to the clear terminal of the D-type flip-flop circuit 20a via the NOT circuit 20b. Further, the output signal of the bobbin sensor 6d is compared with a predetermined voltage, and when the voltage is equal to or higher than the predetermined voltage, it is input to the comparator 20c which outputs a square wave. Then, one output signal of the D-type flip-flop 20a and the comparator 20c
And the output signal of each is input to the 2-input AND circuit 20d. Further, the other inverted output signal of the D-type flip-flop 20a and both output signals of the 2-input AND circuit 20d are input to 4-bit counters 20e and 20f connected in series. As a result, the needle down position sensor 7b detects the needle down position and outputs a high level [High Level] signal, and the pedal switch 9b outputs a high level [Hi Level] signal based on the thread trimming operation command.
gh Level] signal is output, the output signal of the bobbin sensor 6d is counted by the 4-bit counters 20e and 20f, that is, as an 8-bit counter. And the needle position sensor
When 7a detects the needle up position, that is, when the thread cutting operation ends, the counting ends.

On the other hand, the count values of the 4-bit counters 20e and 20f are input as the input value I to the magnitude comparators 20g and 20h. Also, the magnitude comparators 20g and 20h are
I has a set value S corresponding to the lower bobbin thread remaining amount to be detected, which is preset by the 4-bit dip switches 20i and 20j, and I
When the condition of> S is satisfied, a high level [High Level] signal is output to the transistor 20k. As a result, the transistor 20k becomes conductive and the warning lamp 8b lights up.
In this way, when the bobbin 4 rotates by a preset rotation angle or more, the warning lamp 8b is turned on to warn the operator of the remaining amount of lower thread.

Thus, within the scope of the present invention,
Of course, it can be implemented in various modes.

Effects of the Invention As described above in detail, according to the lower thread remaining amount detecting device of the sewing machine of the present invention, the remaining amount of the lower thread wound around the bobbin at the stage of performing the thread cutting operation after the sewing work is completed. When the amount is less than the set amount, the operator can easily know the consumption of the lower thread by a warning from the sewing machine, which is an excellent effect.

Further, according to the present invention, the bobbin of the sewing machine is provided with an optical mark portion on one side flange portion and a pair of light source and light receiving element are used. Since the lower thread remaining amount is determined by detecting the rotation state of the lower thread remaining amount, it is possible to provide a lower thread remaining amount detecting device with high detection accuracy and sufficient reliability.

Further, in addition to each of the above effects, there are advantages that the steps in the sewing work can be shortened, the work efficiency can be improved, and a flexible response can be made to the case where various kinds of bobbin threads are exchanged and used at any time.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram conceptually illustrating the basic configuration of the present invention, and FIG. 2 is a schematic configuration diagram of a sewing machine including a lower thread remaining amount detecting device of a sewing machine according to a first embodiment of the present invention. FIG. 3 is a partial sectional view of a thread ring catcher used in the first embodiment of the present invention and a peripheral mechanism of a photodetector, and FIG. 4 is a side view of a bobbin used in the first embodiment of the present invention. FIG. 6 is a side view of the thread cutting mechanism used in the first embodiment of the present invention, FIG. 6 is a front view of the same, FIG. 7 is a perspective view for explaining the same operation, and FIG. 8 is a main part of FIG. FIG. 9 is an enlarged view, FIG. 9 is a block diagram for explaining the configuration of the electronic control circuit used in the first embodiment of the present invention, and FIG. 10 is a flowchart of processing executed by the electronic control circuit in the first embodiment of the present invention. FIG. 11 is a flowchart showing the details of the lower thread remaining amount detection processing in the flowchart shown in FIG. 12 FIG timing chart showing an example of a control timing performed in the first embodiment the present invention, 13 flowchart diagram illustrating the process of the present invention a second embodiment is executed by the electronic control circuit, 14
13 is a flowchart showing the details of the process for teaching the lower thread remaining amount set value in the flowchart shown in FIG. 13, and FIG. 15 is the flowchart showing the details of the process for detecting the lower thread remaining amount in the flowchart shown in FIG. FIG. 16 is a flow chart, FIG. 16 is a timing chart showing an example of control timing performed in the second embodiment of the present invention, and FIG. 17 is a block diagram for explaining the configuration of an electronic control circuit used in another embodiment of the present invention. ,. 1 …… Automatic lockstitch thread trimming sewing machine 2 …… DC motor 4 …… Bobbin 5 …… Thread trimming mechanism 6 …… Photodetector 6c …… Bobbin sensor light source 6e …… Bobbin sensor 7 …… Needle position detector 8b …… Warning Light 9b …… Pedal switch 10 …… Electronic control circuit

Front page continuation (72) Inventor Katsuhiko Sato 9-35 Hotta-dori, Mizuho-ku, Nagoya, Aichi Brother Industries, Ltd. (56) Reference JP-A-56-116487 (JP, A) JP-A-61-232887 (JP, A)

Claims (3)

[Claims] 1. A thread trimming signal generating means for generating a thread trimming signal based on an instruction from an operator, and a thread trimming means for feeding a certain amount of the lower thread wound on a bobbin according to the thread trimming signal and cutting the bobbin thread. A bobbin thread remaining amount detecting device for a sewing machine, wherein the bobbin is rotated by a predetermined amount and the bobbin is rotated. When it is determined that the thread cutting means is performing the thread cutting operation on the basis of the above, the rotation state of the bobbin detected by the rotation state detection means meets the predetermined condition determined based on the remaining amount of the bobbin thread. A bobbin thread remaining amount detecting device for a sewing machine, comprising: a judging means for outputting the judgment result when it is judged to be applicable. 2. The bobbin thread remaining amount detecting device according to claim 1, wherein the rotating state detecting means detects the number of rotations of the bobbin as the rotating state. 3. The bobbin thread remaining amount detecting device according to claim 1, wherein the rotating state detecting means detects the rotating angle of the bobbin as the rotating state.