JPH0880394A - Bobbin thread residual quantity detector - Google Patents

Abstract

PURPOSE: To provide a bobbin thread residual quantity detector capable of detecting the residual quantity of bobbin thread with high accuracy. CONSTITUTION: This detector is constituted by forming a reflection layer 10 which reflects light in the same direction as its incident direction on the surface of the shaft part 9 of a bobbin 3. Since the light reflected on the reflection layer 10 always returns to a sensor 1 after being reflected in the same direction as its incident direction, the erroneous detection of return light due to insufficient light quantity can be prevented from occurring. which enables the residual quantity of the bobbing thread to be detected with high accuracy. The reflection layer 10 can be prevented from being damaged due to contact with the bobbin thread 16, etc., by forming the reflection layer 10 on the bottom 15a of a recessed part 15 formed deeper than the reflection layer. A groove 8 is provided circumferentially in the center of the shaft part 9, and the bobbin thread 16 can be wound always from the center when it is wound by using the bobbin 3 whose shaft part surface 9a is inclined advancing the groove 8, and the residual quantity of the bobbin thread can be detected with high accuracy in a state in which fixed residual quantity of thread can be secured irrespective of the illuminating position of the light for a bobbin shaft and a winding method of the thread is further provided.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 5 shows an example of the construction of a conventional bobbin thread remaining amount detecting device. In the figure, 21 is a reflection type optical sensor, 2
2 is a lens, 23 is a bobbin, 24 is a bobbin case, 25
Is a shuttle drive shaft. The optical sensor 21 is arranged perpendicular to the axis of the bobbin 23 so that the light can be emitted vertically to the bobbin 23. The bobbin case 24 includes an optical sensor 21.
A window 26 is provided so that the light from can enter.

The optical sensor 21 is a bobbin case 24 during sewing.
The bobbin 23 is irradiated with light through the window 26 of the. Bobbin 2
When the yarn remaining amount of 3 is sufficient, the light from the optical sensor 21 is applied to the lower yarn 27 wound around the bobbin 23. And
When the amount of the bobbin thread 27 wound around the bobbin 23 is reduced and the surface 28a of the bobbin shaft portion 28 is exposed, the light from the optical sensor 23 is reflected by the surface 28a of the bobbin shaft portion 28 and returns. When this return light is detected by the optical sensor 21, it is determined that the bobbin thread 27 wound around the bobbin 23 has disappeared.

[0004]

However, in the conventional bobbin thread remaining amount detecting device, if the light emitted from the optical sensor 21 to the bobbin 23 does not vertically strike the surface 28a of the bobbin shaft portion 28, as shown in FIG. As shown in a) and (b), the reflected light λR
The amount of light returning to the optical sensor 21 due to deviation may be extremely reduced, or the reflected light λR may be completely deviated from the optical sensor 21. When the amount of light returning to the optical sensor 21 is small, the sensor detection accuracy is reduced, which causes a false detection of the lower thread remaining amount. When the reflected light λR completely deviates from the optical sensor 21, it becomes completely undetectable.

Therefore, in the conventional bobbin thread remaining amount detecting device, when the optical sensor 21 is assembled, highly accurate adjustment is required so that the optical axis of the optical sensor 21 is completely perpendicular to the axis of the bobbin 23. It had been. In addition, since it is necessary to irradiate the light from the optical sensor 21 perpendicularly to the surface of the bobbin shaft, only the bobbin whose shaft surface is straight can be used, and for example, FIGS.
It could not be applied to an irregular shape having a slanted shaft surface as shown in FIG.

A conventional bobbin thread remaining amount detecting bobbin has grooves 29a and 29b at both ends of a bobbin shaft 28 as shown in FIG.
Is provided so that a certain amount of yarn can be secured in the grooves 29a and 29b, and the light of the optical sensor 21 is applied to a position outside the grooves 29a and 29b of the bobbin shaft portion 28. As a result, the reflected light is detected by the optical sensor 21 with a certain amount of thread left in one of the grooves 29a, 29b, and the bobbin replacement timing can be known before the bobbin 23 is completely depleted of bobbin thread. .

However, in this type of bobbin thread remaining amount detecting device, the light from the optical sensor 21 is applied to a position near one end of the bobbin shaft portion 28 (in the vicinity of the upper groove 29a in FIG. 1). A great variation occurs in the remaining amount detection of the bobbin thread depending on whether the bobbin 23 is wound right-handed or left-handed. When the bobbin is wound on the bobbin 23, the bobbin 23 starts to be wound from one of the grooves 29a and 29b.
This is because the remaining thread differs depending on whether the thread is right-handed or left-handed, as indicated by diagonal lines in (a) and (b). To suppress this variation, light may be emitted to the central portion of the bobbin shaft portion 28. However, a not-shown pot accommodating the bobbin case 24 becomes an obstacle on the optical path and the bobbin shaft portion 28 is irradiated with light. Can not do it. Changing the shape of the hook is not desirable because it may cause problems with the quality of the sewing.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bobbin thread remaining amount detecting device which solves the above problems of the prior art and is capable of accurately detecting the remaining amount of the bobbin thread.

[0009]

In order to achieve the above object, a bobbin thread remaining amount detecting device of the present invention irradiates a bobbin with light,
Assuming a bobbin thread remaining amount detection device configured to detect the remaining amount of the bobbin thread wound around the shaft by detecting the light reflected back by the shaft of the bobbin, On the surface of the shaft that has a curved surface or a slope in the axial direction,
A reflection layer for reflecting light in the same direction as the incident direction is formed (Claim 1).

In the bobbin thread remaining amount detecting device of the present invention, it is preferable that a groove is provided around the center of the shaft portion and the surface of the shaft portion is inclined toward the groove portion (claim 2).

Further, it is preferable that a concave portion deeper than the reflecting layer is formed on the surface of the shaft portion, and the reflecting layer is formed on the bottom surface of the concave portion.

According to the bobbin thread remaining amount detecting device of the present invention, the light radiated to the reflecting layer on the surface of the bobbin shaft portion is always reflected in the same direction as the incident direction and returns. It is possible to prevent an erroneous detection due to a decrease in the amount and to accurately detect the remaining amount of the lower thread. Further, since the reflected light can be surely detected without vertically injecting the light onto the surface of the shaft portion of the bobbin, it is not necessary to consider the mounting accuracy of the optical sensor as long as the light can be irradiated to the reflective layer. , A bobbin whose shaft surface has any inclination can be used.

By using a bobbin in which a groove is provided in the center of the shaft portion and the surface of the shaft portion is inclined toward the groove portion, the thread is always wound from the center of the shaft portion when the thread is wound. Therefore, the remaining amount of bobbin thread wound on the bobbin can be accurately measured regardless of the irradiation position of the light on the bobbin shaft and the winding method of the thread, with a certain amount of remaining thread always being secured. It becomes possible to detect.

By forming the reflective layer on the bottom surface of the recess deeper than this, it is possible to prevent the yarn wound around the bobbin or the bobbin winder from coming into contact with the reflective layer, so that the reflective layer can be connected to the yarn or the bobbin winder. You can prevent it from being crushed or damaged by contact.

[0014]

EXAMPLE An example of the lower thread remaining amount detecting device according to the present invention will be described below with reference to FIGS. FIG. 1 (a)
FIG. 1 is a schematic side sectional view showing an apparatus configuration of an embodiment of a lower thread remaining amount detecting apparatus of the present invention, and FIG. 1 (b) is a sectional view of a main part of the apparatus. In FIG. 1A, 1 is a reflection type optical sensor, 2 is a lens, 3 is a bobbin, 4 is a bobbin case, 5 is a shuttle drive shaft, and the bobbin case 4 is provided at the tip of the shuttle drive shaft 5. The bobbin 3 in the bobbin case 4 is mounted on a rotary hook (not shown) so that the bobbin 3 in the bobbin case 4 is rotated with the rotation of the rotary hook drive shaft 5. A window 6 is provided on a side portion of the bobbin case 4 so that light from the optical sensor 1 can enter, and the lens 2 and the optical sensor 1 face each other so that their optical axes coincide with each other. It is arranged.

A groove 8 is provided in the center of the shaft portion 3a of the bobbin 3 of the bobbin thread remaining amount detecting device of the present embodiment in a direction perpendicular to the axis thereof. Further, the surfaces of both sides of the groove 8 of the shaft portion 9 are
It is a conical inclined surface 9a that reduces in diameter from both ends of the shaft portion 9 toward the groove 8 at a predetermined inclination angle ψ. Then, on each of the inclined surfaces 9a, a reflection layer 10 having a reflection characteristic that the reflected light λR returns in the same direction as the incident light λI is formed one by one. In this case, as shown in FIG. 1B, the reflective layer 10 is composed of a reflective tape 14 in which a large number of glass beads 13 are sandwiched between a transparent surface film 11 and a reflective film 12, and the inclined surface 9a portion is formed. Forming a recess 15 deeper than the thickness of the reflective tape 14 along the inclined direction,
By attaching the reflection tape 14 to the bottom surface 15a, the inclined surface 9a is embedded.

Next, the operation of this embodiment will be described.
The optical sensor 1 irradiates the bobbin 3 with light through the lens 2 during sewing and the window 6 of the bobbin case 4. When the remaining amount of yarn on the bobbin 3 is sufficient, the light from the optical sensor 1 is applied to the yarn 16 wound on the bobbin 3. Then, when the thread 16 wound around the bobbin 3 becomes less and the surface of the bobbin shaft portion 9 is exposed, the light from the optical sensor 1 is emitted from the surface of the bobbin shaft portion 9 from the time when the light irradiation position is exposed. It begins to be reflected.

However, in this case, since the surface of the bobbin shaft portion 9 is the inclined surface 9a and the reflective layer 10 is formed on a part thereof, when the reflective layer 10 is irradiated with light ( The direction of the reflected light λR is different between the case shown in FIG. 2A and the case where the other part is irradiated (FIG. 2B), and the amount of the reflected light λR returning to the optical sensor 1 is different. .
Since the bobbin 3 is rotating, the reflected light λR from the bobbin 3 returns to the optical sensor 1 as a pulse signal as shown in FIG. 3 due to the difference in the amount of light. Therefore, by setting the threshold value of the pulse signal generated only when the reflected light λR from the reflective layer 10 is received,
When a pulse signal having an intensity exceeding this threshold value is detected, it can be determined that the yarn 16 on the bobbin 3 is gone.

As described above, according to the bobbin thread remaining amount detecting apparatus of this embodiment, since the reflecting layer 10 is provided on the surface of the bobbin shaft portion 9, the light applied to the reflecting layer 10 is: Since the light always reflects in the same direction as that of the incident direction and returns, it is possible to prevent erroneous detection due to the insufficient amount of light received by the optical sensor 1 and detect the remaining amount of the lower thread 16 with high accuracy. Further, since the reflected light λR can be surely detected without vertically injecting the light onto the surface of the shaft portion 9 of the bobbin 3, if the light can be applied to the reflective layer 10, the assembling accuracy of the optical sensor 3 becomes a problem. No need.

By embedding the reflection layer 10 in the bottom surface 15a of the recess 15 deeper than the recess 15, the bobbin thread 16 wound around the bobbin 3 and the thread winding device are prevented from coming into contact with the reflection layer 10. It is possible to prevent the reflective layer 10 from being crushed or damaged by contact with the lower thread 16 or the bobbin winding device.

Further, since the groove 8 is provided in the center of the bobbin shaft portion 9 and both side portions of the groove 8 are formed as the inclined surfaces 9a, the bobbin thread portion 16 is always wound from the center portion of the bobbin shaft portion 9 at the time of thread winding. The bobbin 3 is wound around the bobbin 3 regardless of the light irradiation position on the bobbin shaft portion 9 and the winding manner of the bobbin thread 16. It is possible to accurately detect the remaining amount of the yarn 16.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the reflective tape is used for the reflective layer 10 has been described as an example, but a reflective film or paint having a reflection characteristic equivalent to this may be used.

The reflective layer 10 may be formed at two or more positions on each inclined surface 9a of the bobbin shaft portion 9, or may be formed on the entire inclined surface 9a.

Further, the bobbin 3 is not limited to the one having the above structure, and it is possible to use a bobbin having a wide variety of shaft portions as shown in FIGS. 4 (a) to 4 (i).

[0024]

In summary, the bobbin thread remaining amount detecting device of the present invention can exert the following excellent effects. (1) According to the bobbin thread remaining amount detecting device of claim 1, a reflecting layer for reflecting light in the same direction as the incident direction is formed on the surface of the shaft portion having a curved surface or an inclined surface in the axial direction of the bobbin. As a result, the light radiated to the reflecting layer on the surface of the bobbin shaft will always be reflected in the same direction as the incident direction and will return. The remaining amount of yarn can be detected. Further, since the reflected light can be surely detected without vertically injecting the light onto the surface of the shaft portion of the bobbin, it is not necessary to consider the mounting accuracy of the optical sensor as long as the light can be irradiated to the reflective layer. , A bobbin whose shaft surface has any inclination can be used. (2) In the bobbin thread remaining amount detecting device according to claim 2, a bobbin is used, in which a groove is provided in the center of the shaft portion, and the surface of the shaft portion is inclined toward the groove portion. Due to
When winding the thread, the thread will always be wound from the center of the shaft, so regardless of the light irradiation position on the bobbin shaft and the way the thread is wound, always keep a constant amount of thread remaining,
The remaining amount of the bobbin thread wound on the bobbin can be accurately detected.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a lower thread remaining amount detecting device of the present invention, FIG. 1A is a schematic side sectional view showing the device configuration of the lower thread remaining amount detecting device, and FIG. FIG.

2 is a diagram showing a light reflection state in the apparatus of FIG.
(A) is a case where light is irradiated to the reflection layer portion of the bobbin shaft portion, and (b) is a case where light is irradiated to the portion other than the reflection layer.

FIG. 3 is a diagram showing an example of a light receiving pulse waveform.

FIG. 4 is a front view showing bobbins of various shapes applicable to the apparatus of FIG.

FIG. 5 is a schematic side sectional view showing a device configuration example of a conventional bobbin thread remaining amount detection device.

FIG. 6 is a schematic diagram showing a light reflection state in a conventional device.

FIG. 7 is a schematic view showing a remaining state of a lower thread in a conventional device.

[Explanation of symbols]

 1 Optical Sensor 2 Lens 3 Bobbin 4 Bobbin Case 5 Kettle Drive Shaft 8 Groove 9 Shaft 9a Inclined Surface (Shaft Surface) 10 Reflective Layer 15 Recess 15a Bottom 16 Lower Thread

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Okamura 1-2-2, Kokuryo-cho, Chofu-shi, Tokyo Inside Juke Co., Ltd.

Claims (2)

[Claims] 1. A bobbin is irradiated with light, and the amount of lower thread wound around the shaft is detected by detecting the light reflected by the shaft of the bobbin and returning. In the yarn remaining amount detecting device, a reflection layer that reflects light in the same direction as the incident direction is formed on the surface of a shaft portion having a curved surface or a slope in the axial direction of the bobbin, Detection device. 2. The bobbin thread remaining amount detecting device according to claim 1, wherein a groove is provided around the center of the shaft portion, and the surface of the shaft portion is inclined toward the groove portion.