JPH07204378A - Residual volume detection method of bobbin thread in sewing machine and device thereof - Google Patents

Abstract

PURPOSE:To simply and precisely detect the residual volume of a bobbin thread, by detecting the wound volume of thread on a bobbin when winding up it and detecting the unwound volume of the thread from the bobbin when sewing and subtracting the detected unwound volume out of the wound-up volume in a memory. CONSTITUTION:A bobbin 4 contained in a bobbin case 3 is rotated on sewing and the thread wound up thereon is unwound, in a sewing machine body 1. On the other hand, the bobbin 4 set in a winding device 9 of bobbin thread driven by a sewing machine pulley 7 through a sewing machine belt 8 is rotated on winding up the thread. In this case, the wound-up volume of thread on a bobbin 4 and the rewound volume are detected by detectors 11, 12. The unwound volume detected is retracted from the wound-up volume in a memory in a control box 13 of a sewing machine to detect the residual volume of the thread on the bobbin. In this way, the residual volume of thread can easily and precisely be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bobbin thread remaining amount detecting method and a bobbin thread remaining amount detecting apparatus in a sewing machine.

[0002]

2. Description of the Related Art In a conventional bobbin thread remaining amount detecting method and device in a sewing machine, (1) as shown in FIGS. 11 and 12, a special bobbin case 72 having a hole 71 at each completion of a sewing process is formed. A detector 73 is inserted through the hole 71 to detect the remaining amount of the bobbin thread 75 of the bobbin 74. (2) A special bobbin 77 having a hole 76 as shown in FIG. 13 and FIG. When the bobbin thread is used up and the bobbin thread disappears from the portion corresponding to the hole 76, the detector 78 detects the bobbin thread. (3) Assume the amount of thread wound on the bobbin. It is well known that the number is subtracted for each number of revolutions of the sewing machine and the number of stitches when sewing.

[0003]

However, in the conventional case (1), it is necessary to insert the detector 73 into the special bobbin case 72 to detect the remaining thread amount each time sewing is completed. It cannot be used when continuous sewing is performed, and the detector 7 is placed in the bobbin case 72 every time sewing is completed.
3 had to be inserted, and there was a problem that the work efficiency deteriorated.

In the conventional case of (2), when the detector 78 detects during sewing, the sewing machine is stopped at that time and the bobbin 77 is stopped.
It is necessary to replace and sew again, which makes it easier to produce defective sewing products. Further, since the special bobbin 77 is used, the amount of thread wound around the bobbin 77 is reduced,
The number of replacements also increased and the work efficiency deteriorated. (3)
In the conventional case, the amount of thread wound on the bobbin is assumed, and the number is reduced by the number of revolutions of the sewing machine and the number of stitches at the time of sewing. Therefore, there is a problem that it is not possible to accurately detect the amount of remaining thread on the bobbin.

In view of the above problems, the present invention is capable of detecting the remaining bobbin thread amount in a simple and accurate manner, and enables the sewing to be economical and have excellent work efficiency. is there.

[0006]

The first technical means of the present invention for solving this technical problem detects the winding amount of the yarn when winding the yarn onto the bobbin and stores the yarn amount. At the same time, the amount of delivered yarn of the bobbin at the time of sewing is detected, and the detected amount of delivered yarn is subtracted from the stored amount of yarn.

A second technical means is a winding yarn amount detector for detecting the winding yarn amount when winding the yarn on the bobbin,
A bobbin thread amount detector for detecting the bobbin thread amount at the time of sewing, a storage means for storing the take-up thread amount detected by the take-up thread amount detector, and a take-out thread amount detected by the take-up thread amount detector And a calculating means for subtracting the yarn amount from the stored yarn amount.

[0008]

When the yarn is wound onto the bobbin 4, the winding yarn amount detector 11 detects the winding yarn amount, and the storing means 62 stores the yarn amount. At the time of sewing, the delivered yarn amount detector 12 detects the amount of delivered yarn of the bobbin 4, and the calculated delivered yarn amount is subtracted from the stored yarn amount. Then, it is determined whether or not the subtracted value is the same as the preset remaining amount, and when the subtracted value is the same as the preset remaining amount, an alarm is issued by the alarm buzzer 48 or the like.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 4 and 5, 1 is a sewing machine main body, 2 is a sewing machine hook, 3 is a bobbin case, and a bobbin 4 is housed in the bobbin case 3 as shown in FIG. The bobbin 4 is rotated around the axis so that the yarn wound around the bobbin 4 is paid out. Bobbin 4
As shown in FIG. 8, the pair of flanges are formed with four holes 5 at equal intervals in the circumferential direction. In addition, the collar portion of the bobbin 4 has a number 6 for identifying each bobbin 4.
Is attached.

Reference numeral 7 is a sewing machine pulley, 8 is a sewing machine drive belt, and 9 is a bobbin thread winder.
The rotation of the sewing machine pulley 7 is transmitted to the bobbin thread winder 9 through the sewing machine drive belt 8 during sewing, and the bobbin 4 mounted on the bobbin thread winder 9 is rotated around the axis. Then, as shown in FIGS. 9 and 10, the thread 10 is wound around the bobbin 4.

Reference numeral 11 is a winding amount detector for detecting the winding amount of the yarn on the bobbin 4, and this winding amount detector 11
Is to detect each hole 5 of the bobbin 4 using light,
As shown in FIGS. 9 and 10, the bobbin 4
The winding detection signal is output each time each hole 5 is brought into a position corresponding to the detector 11 by the rotation about the axis.

Reference numeral 12 is a delivery amount detector for detecting the delivery amount of the yarn on the bobbin 4, and the delivery amount detector 12 is
This is to detect each hole 5 of the bobbin 4 by using light.
Also, as shown in FIG. 10, when the thread is sewn, the bobbin 4 is rotated about its axis to output a feed-out detection signal each time each hole 5 comes to a position corresponding to the detector 12.

Although the detectors 11 and 12 detect the movement of the hole 5 of the bobbin 4 as shown in FIGS. 9 and 10,
Even if many threads are wound, since the thread has a poor light reflectance,
As in the case where the number of threads is small, it can be detected accurately without being affected by the threads. Reference numeral 13 is a control box of the sewing machine, and a display unit, switches, lamps, etc. are provided on the surface of the control box 13 as shown in FIG.
Further, in the control box 13, there is provided a control device 14 which will be described later and is constituted by a microcomputer or the like.

In FIG. 6, 17 is a remaining thread amount display portion,
The remaining thread amount of the bobbin thread of the bobbin 4 being sewn is digitally displayed. A set remaining amount display portion 18 digitally displays the set remaining amount of the bobbin thread being sewn. A bobbin number display section 19 digitally displays the number 6 of the bobbin 4 being sewn.
Reference numeral 21 denotes a winding yarn amount display portion, which digitally displays the winding yarn amount of the bobbin yarn being wound. Reference numeral 22 is a bobbin number display section, which digitally displays the number 6 of the bobbin 4 during winding of the yarn.

Reference numeral 23 is a display change switch for each display unit 1.
This is for increasing the numbers displayed on 7, 18, 19, 21, and 22. Reference numeral 24 is a display change switch for reducing the number displayed on each display section 17, 18, 19, 21, 21. 31 is the remaining thread amount display section 17
When the display change switch 23 is pressed with the remaining thread amount change switch 31 being pressed, the display change switch 23 is changed.
When the display change switch 24 is pressed while the remaining thread amount change switch 31 is pressed while the display of the corresponding thread amount display section 17 is increased by 1 for each pressing operation of the display change switch 24, The display of the yarn amount display section 17 corresponding to each pressing operation is changed so as to be decreased by one. 32 is a set remaining amount display section 18
When the display change switch 23 is pressed while the remaining amount setting switch 32 is being pressed with the remaining amount setting switch for setting the remaining amount of the bobbin thread being sewn, the display changing switch 23 The display of the set remaining amount display portion 18 corresponding to each pressing operation is changed so as to be increased by one, and when the display changing switch 24 is pressed while the remaining amount setting switch 32 is pressed, the display changing switch 24 is pressed. The display of the set remaining amount display portion 18 corresponding to each operation is changed so as to be decreased by one. 33 is a sewing bobbin setting switch for changing the display of the bobbin number display section 19 and setting the bobbin 4 to be sewn. When the display changing switch 23 is pressed while the sewing bobbin setting switch 33 is pressed, the display is changed. Bobbin number display section 19 corresponding to each pressing operation of the switch 23
When the display change switch 24 is pressed while the remaining amount setting switch 32 is pressed, the bobbin number display section 19 corresponding to each pressing operation of the display change switch 24 is displayed. Is made variable so that it becomes smaller by one.

Reference numeral 35 is a winding yarn amount change switch for changing the display of the winding yarn amount display portion 21. When the display change switch 23 is pressed while the winding yarn amount change switch 35 is pressed, the display is made. When the display of the winding yarn amount display section 21 corresponding to each pressing operation of the change switch 23 is changed so as to be increased by 1, and the display changing switch 24 is pressed while the winding yarn amount changing switch 35 is pressed. The display of the winding yarn amount display section 21 corresponding to each pressing operation of the display change switch 24 is changed so as to be decreased by one. 36 is a winding bobbin setting switch for changing the display of the bobbin number display section 22 to set the bobbin for winding the yarn. The display changing switch 23 is pressed with the winding bobbin setting switch 36 pressed.
When is pressed, the display of the bobbin number display portion 22 corresponding to each pressing operation of the display change switch 23 is changed so as to be increased by one, and the display change switch 24 is pressed while the winding bobbin setting switch 36 is pressed. When the pressing operation is performed, the display of the bobbin number display portion 22 corresponding to each pressing operation of the display change switch 24 is changed so as to be decreased by one.

Reference numeral 39 is a feed-out yarn amount detection start switch for causing the feed-out yarn amount detector 12 to start a detection operation, and switches the feed-out yarn amount detector 12 between a detection operation state and a non-operation state each time the pressing operation is performed. It has become.
Reference numeral 40 denotes a detection start lamp, which is used to feed the yarn amount detector 12
Lights up when is in the detection operation state, and the delivered yarn amount detector 1
2 indicates that it is in the detection operation state. Reference numeral 41 denotes a memory switch, which is a remaining thread amount display unit 17, a set remaining amount display unit 18,
The remaining thread amount, the set remaining amount and the bobbin number displayed on the bobbin number display section 19 are changed and stored in the control device 14,
Alternatively, the remaining thread amount, the set remaining amount, and the bobbin number stored in the control device 14 side are changed and displayed on the remaining yarn amount display section 17, the set remaining amount display section 18, and the bobbin number display section 19, and pressed. The sewing end signal is output by the operation.

Reference numeral 43 denotes a winding yarn amount detection start switch for causing the winding yarn amount detector 11 to start the detecting operation. The winding yarn amount detector 11 detects the operating state and the non-operating state each time the pressing operation is performed. It is designed to switch to.
Reference numeral 44 is a detection start lamp, which is a winding yarn amount detector 11
Lights up when is in the detection operation state, and the winding yarn amount detector 1
1 indicates that it is in the detection operation state. Reference numeral 45 denotes a memory switch, which is a winding yarn amount display section 21 and a bobbin number display section 2
The winding yarn amount and the bobbin number displayed in 2 are changed and stored in the control device 14 side, or the winding yarn amount and the bobbin number stored in the control device 14 side are stored in the winding yarn amount display portion 21, the bobbin. This is for changing and displaying the number on the number display section 22, and is adapted to output a winding end signal when pressed.

Reference numeral 48 is an alarm buzzer, and 49 is an alarm buzzer 48.
Is a buzzer switch for turning on and off, 50 is an alarm lamp, and 47 is a signal extracting portion. Reference numeral 51 is a power switch, and 52 is a power lamp. In FIG. 1, the control device 14 includes a control unit 53 and a storage unit 54, and the control device 14 includes a remaining yarn amount display unit 17, a set remaining amount display unit 18,
Signals are input / output between the bobbin number display section 19 and the winding thread amount display section 21, and the remaining thread amount change switch 31, the remaining amount setting switch 32, the sewing bobbin setting switch 33, and the winding thread amount change switch 35. The signals from the winding bobbin setting switch 36, the let-off yarn amount detection start switch 39, the memory switch 41, the winding yarn amount detection start switch 43, and the memory switch 45 are input. Further, the detection start lamp 40, the detection start lamp 44, and the alarm buzzer 4
8. A signal is output to the alarm lamp 50 to operate them.

The control section 54 has a payout judging means 55, a winding judging means 56, a remaining thread amount calculating means 57, a winding thread amount calculating means 58, a sewing end judging means 59, a winding end judging means 60, and a set amount comparison. Having means 61. The feeding-out determination means 55 determines whether or not a feeding-out signal is input from the feeding-out yarn amount detector 12. Winding discrimination means 5
6 determines whether or not a winding detection signal is input from the winding yarn amount detector 11. The remaining thread amount calculation means 57
Every time a feeding-out detection signal is input from the feeding-out yarn amount detector 12, 1 is subtracted from the stored yarn amount.

The winding yarn amount calculating means 58 adds 1 to the stored yarn amount every time when the winding detection signal is inputted from the winding yarn amount detector 11. Sewing end determination means 59
Determines whether or not a sewing end signal has been input from the memory switch 41. The winding end determination means 60 determines whether or not a winding end signal is input from the storage switch 45. The set amount comparing means 61 compares and determines whether or not the set remaining amount set by the remaining amount setting switch 32 and the winding yarn amount calculated by the winding yarn amount calculating means 58 are the same.

The storage section 54 includes a large number of yarn amount storage means 6
Each yarn amount storage means 62 stores the yarn amount calculated by the remaining yarn amount calculating means 57 or the winding yarn amount calculating means 58 in association with the bobbin number 6. Also,
The yarn amount storage means 62 can freely change the memory of the yarn amount manually. That is, with the sewing bobbin setting switch 33 pressed, the display change switch 23
Alternatively, the display change switch 24 is pressed to change the display of the bobbin number display section 19, and the display change switch 23 or the display change switch 24 is pressed while the remaining thread amount change switch 31 is pressed to change the remaining thread amount. After the display on the display unit 17 is changed, the memory switch 41 is pressed to store the thread amount storage means 62 corresponding to the bobbin number displayed on the bobbin number display unit 19 on the remaining thread amount display unit 17. The amount of thread is changed.

Next, the winding yarn amount detecting operation will be described with reference to the flowchart of FIG. After the power switch 51 is turned on and the power lamp 52 is turned on, when the winding yarn amount detection start switch 43 is pressed, the detection start lamp 44 is turned on and the winding yarn amount detector 11 is in the detection operation state. Further, all the displays of the winding yarn amount display portion 21 and the bobbin number display portion 22 become zero.

Then, the display changing switch 23 or the display changing switch 24 is pressed while the winding bobbin setting switch 36 is being pressed, and the bobbin number display section 22 displays the number of the bobbin 4 about to be wound. Match 6 Then, when the bobbin 4 of No. 6 is attached to the bobbin thread winding device 9 and the sewing machine pulley 7 is rotated, the thread is wound on the bobbin 4.

At this time, the control device 14 starts the winding yarn amount detecting operation by pressing the winding yarn amount detecting start switch 43. First, in step 1, the winding yarn amount detector 11 by the winding discriminating means 56. It is determined whether or not the winding detection signal is input, and if the winding detection signal is input, the process proceeds to step 2. If the winding detection signal is not input, the process returns to step 1 and the winding detection signal is input. The determination is repeated whether or not.

In step 2, 1 is added to the stored yarn amount (0 at the beginning), and the process proceeds to step 3. In step 3,
The winding end determination means 60 determines whether or not the winding end signal is input from the memory switch 45. If the winding end signal is not input, the process returns to step 1. Therefore,
When the bobbin 4 attached to the bobbin thread winder 9 rotates and the thread is wound around the bobbin 4, 4 /
The winding detection signal is input for each rotation, and the number of input winding detection signals is counted as the yarn amount.

When the winding end signal is input in step 3, the process proceeds to step 4, and the yarn amount calculated by the yarn amount calculating means 58 in step 4 corresponds to the bobbin number 6 by the yarn amount storing means 62. And remember. Therefore, when the winding of the yarn is completed, the memory switch 45 is pressed to store the amount of yarn wound up to that time in the yarn amount storage means 62 in association with the bobbin number 6. Therefore, in sewing, many bobbins 4 are required due to changes in thread thickness, thread color, thread material, etc., but the thread amount of many bobbins 4 can be stored for each bobbin number 6.

Next, the remaining thread amount detecting operation will be described with reference to the flowchart of FIG. When sewing using the bobbin 4 that has wound up the thread, when the feed-out thread amount detection start switch 39 is pressed, the detection start lamp 40 lights up and the feed-out thread amount detector 12 enters the detection operation state. Further, the displays of the remaining thread amount display portion 17 and the bobbin number display portion 19 are all zero.

Then, while the sewing bobbin setting switch 33 is being pressed, the display change switch 23 or the display change switch 24 is pressed to match the display of the bobbin number display section 19 with the number 6 of the bobbin 4 to be sewn. Let After that, when the memory switch 4 is pressed, the thread amount corresponding to the number 6 of the bobbin 4 displayed on the bobbin number display section 19 is pulled out from the thread amount storage means 62, and the thread amount is taken up. Is displayed in. When the display change switch 23 or the display change switch 24 is pressed while the remaining amount setting switch 32 is pressed to set the remaining amount of the bobbin thread being sewn, the set remaining amount is displayed on the set remaining amount display section 18. Is displayed. The set remaining amount is set to a number such that a thread having a length capable of sewing one step of a normal sewing product is left. When sewing is started by driving the sewing machine,
The bobbin 4 in the bobbin case 3 rotates around the axis and the yarn is paid out from the bobbin 4.

At this time, in the control device 14, first, by pressing the memory switch 41, in step 11, the yarn amount corresponding to the number 6 of the bobbin 4 displayed on the bobbin number display section 19 is obtained from the yarn amount storage means 12. The yarn amount that has been pulled out is displayed on the remaining yarn amount display portion 17, and the process proceeds to step 12.
In step 12, the feeding determination means 55 determines whether or not the feeding detection signal is input from the feeding amount detector 12. If the feeding detection signal is not input, the process returns to step 12, and the determination as to whether or not the feeding detection signal is input is repeated.

In step 12, if the feeding detection signal is input, the process proceeds to step 13, and in step 13, the remaining yarn amount calculation means 57 draws the yarn amount from the yarn amount storage means 12 (remaining yarn amount display section 17). Thread amount displayed on
1 is subtracted, and the subtracted thread amount is displayed as the remaining thread amount display section 1
7 is displayed and the process proceeds to step 14. Therefore, when the bobbin 4 in the bobbin case 3 during sewing rotates around the axis and the yarn is fed out from the bobbin 4, the bobbin 4 becomes 1/4.
The display of the remaining thread amount display portion 17 decreases by 1 for each rotation.

At step 14, the sewing end judging means 59 judges whether or not the sewing end signal is inputted from the memory switch 41. Input the sewing end signal and step 1
In step 15, the yarn amount calculated by the remaining yarn amount calculating means 57 is stored in the yarn amount storing means 62 in association with the bobbin number 6. Therefore, when the sewing is completed, the memory switch 41 is pressed to store the remaining thread amount remaining in the bobbin 4 up to that time in the thread amount storage means 62 in association with the bobbin number 6.

If the sewing end signal is not input in step 14, the process proceeds to step 16, and in step 16, the set remaining amount set by the set amount comparing means 61 and the remaining thread calculated by the winding thread amount calculating means 58 are set. It is determined whether or not the quantity is the same, and if they are not the same, step 12
Return to. If they are the same, the process proceeds to step 17 to activate the alarm buzzer 48 and the alarm lamp 50 to issue an alarm,
The signal is taken out from the signal taking-out unit 47 to the outside. The signal extracted to the outside is used, for example, as a signal for actuating another alarm device or stopping driving of the sewing machine. Therefore, if the remaining amount of the bobbin thread during sewing is set to such an extent that a thread having a length capable of sewing one process of the sewn product is left, it is not necessary to replace the bobbin 4 during sewing, and It will also be excellent in terms of work efficiency, quality of sewing products and cost of thread.

Next, when the thread amount stored in the thread amount storage means 62 is changed, the display change switch 23 or the display change switch 24 is pressed while the sewing bobbin setting switch 33 is being pressed, The display of the bobbin number display section 19 is made to coincide with the number 6 of the bobbin 4 whose memory is to be changed, and the display change switch 23 or the display change switch 2 is pressed while the remaining thread amount change switch 31 is pressed.
4 is pressed to change the display of the remaining thread amount display section 17, and then the memory switch 41 is pressed, the bobbin number signal displayed on the bobbin number display section 19 and the remaining thread amount display section 17 are displayed. The signal of the amount of yarn produced is inputted to the control device 14 side, and the memory of the amount of yarn of the yarn amount storage means 12 corresponding to the bobbin number displayed on the bobbin number display unit 19 is displayed on the remaining yarn amount display unit 17. The thread amount is changed. Therefore,
Even when the yarn of the bobbin 4 is entangled and the winding yarn amount of the bobbin 4 is changed midway, the yarn amount stored in the yarn amount storage means 12 can be made to match the actual yarn amount.

In the above embodiment, the take-up yarn amount detector 11 and the pay-out yarn amount detector 12 are configured to detect the presence or absence of the holes 5 by light, but the number of the holes 5 provided in the bobbin 4 is not limited. Is not limited to 4, and may be 1, 2, 3, or 5 or more. Further, the detectors 11 and 12 are not limited to those in the embodiment, and may be ones that detect the number of rotations of the bobbin 4 by magnetic means, for example.

[0036]

According to the present invention, the amount of remaining thread on the bobbin can be detected easily and accurately, and the sewing can be made economical and work efficiency is excellent.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart for explaining a winding yarn amount detecting operation of the present invention.

FIG. 3 is a flow chart for explaining an operation for detecting a delivered yarn amount according to the present invention.

FIG. 4 is a schematic front view of the sewing machine.

FIG. 5 is a plan view of a bobbin thread winder portion of the sewing machine.

FIG. 6 is a front view of a control box portion.

FIG. 7 is a front view of a bobbin case and a bobbin.

FIG. 8 is a perspective view of a bobbin.

FIG. 9 is a principle diagram for explaining a detection operation of a detector.

FIG. 10 is a principle diagram for explaining a detection operation of a detector.

FIG. 11 is a perspective view showing a conventional example.

FIG. 12 is a principle diagram showing a conventional example.

FIG. 13 is a perspective view of a bobbin showing another conventional example.

FIG. 14 is a principle view showing another conventional example.

[Explanation of symbols]

 11 Winding yarn amount detector 12 Feeding yarn amount detector 48 Alarm buzzer 50 Warning lamp 53 Control unit 54 Storage unit 57 Remaining yarn amount calculating means 58 Winding yarn amount calculating means 62 Yarn amount storing means

Claims (7)

[Claims] 1. A winding thread amount is detected at the time of winding the thread on a bobbin and the thread amount is stored, and at the time of sewing, a bobbin thread feeding amount is detected and the detected feeding amount is detected. A method for detecting the remaining amount of bobbin thread in a sewing machine, wherein the thread quantity is subtracted from the stored thread quantity. 2. A winding thread amount is detected when the thread is wound around a bobbin and the thread amount is stored, and at the same time, a bobbin thread feeding amount is detected during sewing and the detected feeding amount is detected. A method for detecting the remaining amount of bobbin yarn in a sewing machine, wherein the yarn amount is subtracted from the stored yarn amount and it is determined whether or not the subtracted value is equal to a preset remaining amount. 3. The winding amount of the wound yarn is detected when the yarn is wound around the bobbin and the yarn amount is stored, and the unwinding amount of the bobbin yarn is detected during sewing, and the detected feeding amount is detected. The yarn amount is subtracted from the stored yarn amount, it is determined whether or not the subtracted value is the same as the preset remaining amount, and an alarm is issued when the subtracted value is equal to the preset remaining amount. A method for detecting the remaining amount of bobbin thread in a sewing machine, which is characterized by being emitted. 4. The method for detecting the remaining amount of the bobbin thread in the sewing machine according to claim 1, wherein the storage of the thread amount is made to correspond to a bobbin number for identifying a bobbin. 5. A take-up yarn amount detector for detecting the take-up yarn amount at the time of winding the yarn on the bobbin, and a take-up yarn amount detector for detecting the take-up yarn amount of the bobbin at the time of sewing. A storage means for storing the winding yarn amount detected by the winding yarn amount detector, and an arithmetic means for subtracting the delivered yarn amount detected by the feeding yarn amount detector from the stored yarn amount. A bobbin thread remaining amount detecting device for a sewing machine. 6. A take-up yarn amount detector for detecting the take-up yarn amount when the yarn is wound onto the bobbin, and a take-up yarn amount detector for detecting the take-up yarn amount of the bobbin during sewing. A storage means for storing the winding yarn amount detected by the winding yarn amount detector, and a computing means for subtracting the delivered yarn amount detected by the delivery yarn amount detector from the stored yarn amount, and the subtraction A bobbin thread remaining amount detecting device in a sewing machine, comprising: a discriminating means for discriminating whether or not the value is equal to a preset remaining amount. 7. The bobbin thread remaining amount detecting device in a sewing machine according to claim 5, wherein the storage means is configured to store the thread amount in association with a bobbin number for identifying a bobbin. .