JPH07265572A - Device for detecting remaining quantity of bobbin thread in sewing machine - Google Patents

Abstract

PURPOSE:To precisely detect a remaining quantity of bobbin thread in a plurality of bobbins with a simple structure which can be obtained by processing thus used bobbins. CONSTITUTION:A device for detecting a remaining quantity of bobbin thread, a bobbin 3 on which a reflective tape 2 for reflecting light onto a bobbin thread winding shaft, is applied, a light source 4 for directing light onto the reflecting tape 2, a photosensor 5 for receiving light radiated from the light source 4 and reflected by the reflective tape 2, computing means for processing a signal from the photosensor 5 so as to compute a remaining quantity of thread in the bobbin 3, and display means for displaying the remaining quantity of thread in the bobbin 3 which is obtained from the result of the computation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the remaining amount of lower thread wound on a lower thread bobbin of a sewing machine.

[0002]

2. Description of the Related Art A sewing machine sews cloth and the like with an upper thread and a lower thread. The lower thread is wound on a lower thread bobbin and stored in a bobbin case inside the sewing machine. Therefore, when the sewing machine is used, the remaining amount of the bobbin thread wound around the bobbin thread bobbin cannot be known. If the bobbin thread breaks during sewing, normal sewing will not be possible.

In order to prevent this adverse effect, a bobbin thread remaining amount detecting device described in the following publication has been developed. SUMMARY OF THE INVENTION A bobbin thread remaining amount detecting device described in this publication is shown in FIG.
This device calculates the remaining amount of the lower thread from the number of rotations of the lower thread bobbin. This device utilizes the property that the rotation of the lower thread bobbin becomes faster when the remaining amount of the lower thread wound around the lower thread bobbin decreases. The lower thread bobbin has a smaller winding radius of the lower thread as the remaining amount of the wound lower thread decreases. When the radius becomes smaller, the number of rotations of the lower thread bobbin increases when the lower thread having the same length is pulled out. Therefore, the remaining amount of the lower thread can be calculated from the number of rotations of the lower thread bobbin. In order to detect the number of rotations of the bobbin bobbin, a magnetic signal generator (not shown) is fixed to the bobbin bobbin, and the magnetic sensor 1 is arranged close to the bobbin bobbin. The magnetic sensor 1 can detect the rotation speed of the lower thread bobbin by measuring the change in the strength of the magnetic field.

Japanese Patent Laid-Open No. 59-67994 and Japanese Utility Model Laid-Open No. 61-118584 disclose that the lower thread bobbin of the lower thread bobbin is determined from the number of rotations of the upper shaft and the lower shaft or the number of vertical movements of the needle bar. Detect the amount. The lower shaft rotates the bobbin case of the lower thread bobbin. The rotation speed of the lower shaft is the rotation speed of the lower thread bobbin. This device also utilizes the characteristic that when the amount of bobbin thread wound around the bobbin bobbin decreases, the rotational speed of the lower shaft increases with respect to the rotational speed of the upper shaft and the number of vertical movements of the needle bar. The remaining amount of bobbin thread is detected.

[0005]

It is difficult for the lower thread remaining amount detecting devices of the sewing machines described in these publications to accurately detect the remaining amount of the lower thread. This is because there is little change in the number of rotations of the bobbin bobbin with respect to the remaining amount of the bobbin thread. For this reason, it is necessary to replace the bobbin thread bobbin with some bobbin thread remaining on the bobbin thread bobbin, and the bobbin thread cannot be used efficiently until the end. It is very important to effectively use the lower thread wound on the lower thread bobbin. In particular, since the mechanism for displaying the remaining amount of the bobbin thread bobbin is often used in industrial sewing machines, if the bobbin thread cannot be used effectively, the amount of wasted thread will be considerably increased. It is extremely important to use for. Furthermore, since the lower thread bobbin is stored in a bobbin case and used by rotating it, it is difficult to make it large, and the total length of the wound thread is too short to compare with the upper thread. For this reason, if the remaining amount of yarn on the lower yarn bobbin becomes long, many yarns are wasted and cannot be used. Furthermore, the time for replacing the bobbin thread bobbin is shortened and the sewing efficiency is reduced.

Furthermore, when winding the lower thread around the lower thread bobbin taken out from the sewing machine, it is necessary to remove the remaining lower thread and wind a new lower thread. Therefore, when the remaining amount of the lower thread is long, there is a drawback that it takes time and effort to remove the remaining lower thread.

Further, in the device described in Japanese Patent Laid-Open No. 52-4354, it is necessary to fix the magnetic signal generator to the lower thread bobbin in order to detect the rotation speed of the lower thread bobbin. Therefore, there is a drawback that the structure of the lower thread bobbin becomes complicated and the cost becomes high. In particular, since a plurality of bobbin thread bobbins are used for one sewing machine, mounting the magnetic signal generators on all the bobbin thread bobbins may increase the overall cost. Further, since the lower thread bobbin is stored in a bobbin case and used by rotating, the size is limited. Therefore, fixing the magnetic signal generator to the small bobbin bobbin has a drawback that it is very troublesome.

The present invention was developed with the object of solving this drawback. An important object of the present invention is to provide a bobbin thread remaining amount detecting device for a sewing machine which has an extremely simple structure and which can accurately detect a bobbin thread remaining amount of a bobbin thread bobbin and use the bobbin thread effectively and without waste. is there. Another important object of the present invention is to manufacture a plurality of lower thread bobbins at a low cost, and to perform a simple processing on a small lower thread bobbin to accurately detect the remaining lower thread bobbin. A yarn remaining amount detecting device is provided.

[0009]

In order to achieve the above-mentioned object, a lower thread remaining amount detecting device for a sewing machine of the present invention has the following configuration. The bobbin thread remaining amount detecting device includes a bobbin thread bobbin 3 to which a reflection tape 2 that reflects light is attached to a winding shaft, a light source 4 that irradiates the reflection tape 2 of the bobbin thread bobbin 3 with light, and the light source. 4, an optical sensor 5 for receiving the reflected light of the light emitted from the reflection tape 2 of the reflection tape 2, and a calculation means 6 for processing the signal from the optical sensor 5 to calculate the remaining thread amount of the lower thread bobbin 3.
And a display means 7 for displaying the lower thread remaining amount of the lower thread bobbin 3 from the calculation result of the calculating means 6.

Further, in the bobbin thread remaining amount detecting device according to claim 2 of the present invention, the reflection tape 2 is a polarized reflection tape 2,
A polarization filter 8 is arranged between the light source 4 and the polarization reflection tape 2, and further a polarization filter 8 is arranged between the polarization reflection tape 2 and the optical sensor 5.

[0011]

The bobbin thread remaining amount detecting device of the sewing machine of the present invention detects and displays the bobbin thread remaining amount of the bobbin thread bobbin as follows.

The light source 4 irradiates the axis of the bobbin thread bobbin 3 rotated in the bobbin case 9 with light. When the bobbin thread remaining amount of the bobbin thread bobbin 3 is large, the emitted light is reflected by the bobbin thread and is not reflected by the reflection tape 2 attached to the shaft of the bobbin thread bobbin 3. This is because the bobbin thread is wound on the reflective tape 2. When the amount of the lower thread decreases as it is used, the lower thread wound on the reflective tape 2 disappears. When this happens,
The light emitted from the light source 4 is reflected by the reflection tape 2. The light reflected by the reflective tape 2 is received by the optical sensor 5. The reflection tape 2 efficiently reflects the received light and irradiates the optical sensor 5. The optical sensor 5 that receives the light reflected by the reflection tape 2 transmits the light reception signal of the light of the reflection tape 2 to the calculation means 6. For example, the optical sensor 5 outputs a voltage signal for increasing the output voltage when receiving the light from the reflective tape 2.

The calculation means 6 calculates a signal input from the optical sensor 5 to detect that the remaining amount of the lower thread of the lower thread bobbin 3 has decreased. For example, when the optical sensor 5 receives the light from the reflection tape 2 and outputs a voltage signal, when the voltage signal of a certain level or more is input to the calculating means 6, the lower thread of the lower thread bobbin 3 becomes lower than the set value. It is determined that it has decreased.

The calculation result of the calculation means 6 is transmitted to the display means 7, and the display means 7 displays that the lower bobbin thread remaining amount has decreased.

As described above, the bobbin thread remaining amount detecting device of the sewing machine of the present invention irradiates the reflecting tape 2 attached to the winding shaft of the bobbin thread bobbin with light, and the light is received by the optical sensor 5. hand,
Detect the remaining amount of bobbin thread. In this device, when the bobbin thread wound on the reflection tape 2 is used up, the reflection tape 2 reflects light. If there is a lower thread on the shaft of the lower thread bobbin 3,
The reflection tape 2 is hidden by the lower thread and does not reflect light. Therefore, in the device of the present invention, when the lower thread of the lower thread bobbin 3 is almost lost and the reflection tape 2 reflects light,
Accurately display that the bobbin thread remaining amount is low.

As described in claim 2, the reflective tape 2
The device which uses the polarized light reflection tape for the light source 4 and the polarized light reflection tape 2 between the light source 4 and the polarized light reflection tape 2 and the optical sensor 5 effectively uses the polarized light. Thus, there is a feature that the reflected light of the reflection tape 2 can be detected extremely accurately. This is because the optical sensor 5 can distinguish the reflected light of the thread or the metal surface from the reflected light of the polarization filter 8.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a bobbin thread remaining amount detecting device for a sewing machine for embodying the technical idea of the present invention. Not specific to one.

Further, in this specification, for easy understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "claims column", "action column", and "action column". It is added to the members shown in the section of "Means for Solving the Problems". However, the members shown in the claims are
It is by no means specific to the members of the examples.

The lower thread remaining amount detecting device of the sewing machine shown in FIG.
A bobbin thread bobbin 3 having a reflective tape 2 for reflecting light attached to the winding shaft of the bobbin thread bobbin 3, a light source 4 for irradiating the reflective tape 2 of the bobbin thread bobbin 3 with light, and radiation from the light source 4 Sensor 5 for receiving the reflected light of the reflected tape 2 of the reflected light
And a calculation means 6 for processing the signal of the optical sensor 5 to calculate the remaining thread amount of the lower thread bobbin 3, and a display means for displaying the lower thread remaining amount of the lower thread bobbin 3 from the calculation result of the calculating means 6. 7
With.

As shown in FIG. 3, the bobbin thread bobbin 3 has the reflective tape 2 wound and attached to the entire surface of the winding shaft. For the reflective tape 2, a polarized reflective tape 2 (for example, a retroreflective reflective tape 2E39-RSA manufactured by OMRON Corp.) that optimally reflects the incident light by polarizing it by 90 degrees is optimal. This is because it is possible to accurately distinguish the reflected light of the reflective tape 2 and the reflected light of the white thread or the metal surface.

The principle by which the polarized reflection tape 2 distinguishes the reflected light of the reflective tape 2 from the reflected light of the metal surface or the like is shown in FIGS. FIG. 4 shows a state in which the polarized reflection tape 2 reflects light from the light source 4, and FIG. 5 shows a state in which a white thread or a metal surface reflects light. As shown in FIG. 4, the polarized reflective tape 2
Reflects a horizontal wave and converts it to a vertical wave. The reflected light from the white thread or the metal surface is a horizontal wave even if the horizontal wave is reflected. In this way, the light reflected by the polarization reflection tape 2 and the light reflected by the metal surface or the like have different vibration directions. Therefore, when the polarization filter 8 is arranged in front of the optical sensor 5 so as to pass the wave in the vertical direction, only the light reflected by the polarization reflection tape 2 is input to the optical sensor 5. The light reflected by the white thread or the metal surface is cut by the polarization filter 8 and does not enter the optical sensor 5.

As described above, in order to distinguish the polarized reflection tape 2 from the reflected light from the metal surface or the like, the polarizing filter 8 is arranged in front of the light source 4 so that the vibration direction of the light is aligned horizontally or vertically. There is a need. 4 and 5, the light from the light source 4 is converted into a horizontal wave by the polarization filter 8 for easy understanding. It goes without saying that the polarization filter 8 can set the vibration direction of the light of the light source 4 to a direction other than the vertical direction. The polarization filter 8 arranged in front of the light source 4 is arranged in a direction in which the light reflected by the polarization reflection tape 2 is transmitted and the light reflected by the metal surface or the like is not reflected.

In the above embodiment, the polarized reflection tape 2 is used as the reflection tape 2, and the remaining amount of the lower thread is accurately detected by utilizing the polarization of the light. However, the device of the present invention does not specify the reflective tape 2 as the polarized reflective tape 2. A tape that reflects light of a specific wavelength can also be used as the reflective tape 2. Reflective tape 2
When using a tape that efficiently reflects light of a specific wavelength, a filter that transmits the light of the wavelength that the reflective tape 2 efficiently reflects is disposed in front of the optical sensor 5, and the reflected light of the reflective tape 2 Can be efficiently input to the optical sensor 5.

Further, it goes without saying that the reflection tape 2 may be a normal tape that does not polarize incident light and does not selectively reflect a specific wavelength. For the reflective tape 2, a tape that reflects light more efficiently than a thread is used. The calculating means 6 stores the intensities of the reflected light of the thread and the reflected light of the reflective tape 2. The intensity of the input signal from the optical sensor 5 is calculated by the calculating means 6 and it is determined whether the intensity is the reflected light from the reflective tape 2 or the reflected light from the yarn.

The light source 4 emits a focused light beam toward the winding shaft of the bobbin bobbin 3. The bobbin case 9 is provided with a through hole 10 as shown in FIG. 6 in order to transmit the light from the light source 4 to the winding shaft of the bobbin thread bobbin 3. The through hole 10 is opened on the side surface of the bobbin case 9 as shown in FIG. 7. The light source 4 radiates light to the winding shaft of the lower thread bobbin 3 through the through hole 10 of the bobbin case 9. In a device using the polarized reflection tape 2 as the reflection tape 2, a polarization filter 8 (not shown) is arranged in front of the light source 4. The polarization filter 8 aligns the vibration direction of the light emitted from the light source 4 in a certain direction and irradiates the reflection tape 2 with the vibration direction.

The optical sensor 5 is integrated with the light source 4 to form a sensor member 11. The optical sensor 5 is arranged at a position for receiving the light reflected by the reflection tape 2 on the winding shaft. In the device using the polarization reflection tape 2 as the reflection tape 2, a polarization filter 8 for transmitting the reflected light whose vibration direction is changed by the polarization reflection tape 2 is arranged in front of the optical sensor 5. When the optical sensor 5 receives the reflected light from the reflective tape 2, the optical sensor 5 outputs an output signal having a higher voltage, or has a smaller resistance. OMRON E39- on reflective tape 2
The device that uses the RSA polarized reflection tape 2 is the same as the one in which the polarization filter 8 is built in the light source 4 and the optical sensor 5.
E32-R21 etc. can be used.

The optical sensor 5 integrated with the light source 4 is fixed to the bottom surface of the sewing machine body as shown in FIG. The output terminal of the optical sensor 5 is connected to the computing means 6 via a lead wire. The calculation means 6 calculates a signal input from the optical sensor 5 to determine whether the light is reflected light from the yarn or the reflection tape 2
It is determined whether the reflected light is reflected light. When the reflected light from the reflective tape 2 is received, the computing means 6 connected to the optical sensor 5 that outputs a high voltage output signal receives the signal of a certain level or higher from the optical sensor 5 and is reflected by the reflective tape. Two
It is judged as the reflected light from. That is, it is determined that the lower thread remaining amount of the lower thread bobbin 3 has decreased.

When the reflected light from the reflection tape 2 is received, the calculation means 6 for connecting the optical sensor 5 whose resistance becomes small, sends a constant current to the optical sensor 5 through the constant current circuit, and the optical sensor 5 When the voltage across both ends is detected and the voltage across the optical sensor 5 becomes lower than the set value, the reflective tape 2
It is determined that the reflected light is received. Also, this computing means 6
Determines that the constant voltage is connected to the optical sensor 5 in series through a predetermined resistance and the optical sensor 5 receives the reflected light of the reflective tape 2 when the current value exceeds the set value. You can also This is because when the reflected light of the reflective tape 2 is received and the resistance of the optical sensor 5 decreases, the value of the current flowing through the optical sensor 5 increases.

In the display means 7, the calculating means 6 is the bobbin thread bobbin 3.
If it is determined that the remaining amount of the lower thread is small, the result is displayed. The display means 7 indicates that the remaining amount of the bobbin thread is low by means of an LED and a sound. When the bobbin thread amount of the bobbin thread bobbin 3 becomes small, the LED is turned on or blinks and the buzzer sounds to warn. In the device shown in FIG. 2, LEDs are arranged not only in the vicinity of the buzzer but also on the entire surface of the sewing machine main body through lead wires. By disposing an LED on the main body of the sewing machine, the remaining amount of the lower thread can be displayed at a position where it is easy to see.

[0030]

The bobbin thread remaining amount detecting device of the sewing machine of the present invention is
Achieves the following outstanding features that conventional sewing machines have longed for. With an extremely simple structure, the lower thread remaining amount of the lower thread bobbin can be accurately detected and the lower thread can be effectively used without waste. This feature is realized in that the bobbin thread remaining amount detecting device of the sewing machine of the present invention attaches a reflection tape to the winding shaft of the bobbin thread bobbin, irradiates the reflection tape with light from a light source, and irradiates it. This is because the reflected light is reflected by the reflecting tape, the reflected light is detected by the optical sensor, and the calculation means calculates the remaining amount of the bobbin thread. Compared with the magnetic signal generator used in the conventional magnetic signal generator, the reflective tape can be attached to the winding shaft of the bobbin bobbin easily and easily by anyone, even if not an expert. .

The bobbin bobbin to which the reflective tape is attached has a slightly thicker winding shaft. However, the total length of the yarn wound around the central portion of the winding shaft is short, and even if the winding shaft becomes slightly thick, the total length of the bobbin thread that can be wound on the bobbin bobbin does not become so short. The device of the present invention can detect the remaining amount of lower thread very accurately. This is because it detects that the bobbin thread has disappeared on the surface of the reflective tape. Therefore, the lower thread remaining amount detecting device of the present invention can effectively use the lower thread wound around the lower thread bobbin. This is extremely important for an industrial sewing machine equipped with this type of device. This is because a sewing machine used for industrial use has a large sewing distance and therefore uses a large amount of bobbin thread, and it is desired to use the thread as effectively as possible without waste.

The lower thread remaining on the lower thread bobbin can be easily removed. The bobbin thread remaining amount detecting device of the present invention is
This is because it is possible to accurately detect the remaining amount of the bobbin thread and shorten the bobbin thread remaining on the bobbin thread bobbin. Therefore, the device of the present invention has a feature that the extra labor for removing the lower thread from the lower thread bobbin is saved and the sewing can be performed efficiently.

The bobbin bobbin processing can be simplified and the bobbin thread remaining amount can be accurately detected. This is because the bobbin thread remaining amount detecting device of the present invention can detect the bobbin thread remaining amount by attaching a reflection tape to the winding shaft of the bobbin thread bobbin that is small and difficult to mount an extra one. The reflective tape can be easily attached to the winding shaft of the bobbin bobbin. There is no need to specially process the bobbin bobbin to attach the reflective tape. Also, it can be easily attached to all bobbin bobbins. Therefore, the bobbin thread remaining amount detecting device of the present invention has an excellent feature that the bobbin thread bobbin can be easily processed and the bobbin thread remaining amount of all the bobbin thread bobbins to be used can be accurately detected.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a lower thread remaining amount detecting device of a conventional sewing machine.

FIG. 2 is a schematic perspective view of a lower thread remaining amount detecting device of a sewing machine according to an embodiment of the present invention.

FIG. 3 is a perspective view showing an example of a lower thread bobbin.

FIG. 4 is a cross-sectional view showing a state in which reflected light from a reflective tape is identified by using polarized light.

FIG. 5 is a cross-sectional view showing a state in which reflected light of a reflective tape is identified by using polarized light.

FIG. 6 is a side view showing a state in which light is applied to the winding shaft of the lower thread bobbin housed in the bobbin case.

FIG. 7 is a front view showing an example of a bobbin case that accommodates a lower thread bobbin.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetic sensor 2 ... Reflective tape 3 ... Bobbin bobbin 4 ... Light source 5 ... Optical sensor 6 ... Calculation means 7 ... Display means 8 ... Polarization filter 9 ... Bobbin case 10 ... Through hole 11 ... Sensor member

Claims (2)

[Claims] 1. A reflection tape for reflecting light on a bobbin winding shaft.
The bobbin thread bobbin (3) to which (2) is attached and this bobbin thread bobbin
A light source (4) that irradiates the reflection tape (2) of (3) with light, an optical sensor (5) that receives the reflected light of the reflection tape (2) of the light emitted from this light source (4), and this A processing means (6) for processing the signal of the optical sensor (5) to calculate the remaining thread amount of the lower thread bobbin (3),
A bobbin thread remaining amount detecting device for a sewing machine, comprising: a display device (7) for displaying the bobbin thread remaining amount of the bobbin thread bobbin (3) based on the calculation result of the calculating means (6). 2. The reflection tape (2) is a polarization reflection tape, and a polarization filter (8) is provided between the light source (4) and the polarization reflection tape (2).
2. The bobbin thread remaining amount detecting device according to claim 1, further comprising: a polarizing filter (8), and a polarizing filter (8) disposed between the polarizing reflection tape (2) and the optical sensor (5). .