JPH02134191A - Sewing machine bobbin thread amount detection device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a bobbin thread amount detection device for a sewing machine.

[Prior art]

Conventionally, as this type of device, for example,
No. 0685 Public I! (published on November 11, 1986). In this device, when the rotation of the outer hook constituting the thread loop catcher is stopped, a photodetector irradiates light onto the outer periphery of the shaft of the bobbin, detects the reflected light, and detects the reflected light. It is designed to detect the remaining amount of bobbin thread at the top.

[Problem to be solved by the invention]

However, in the above-mentioned device, the detection sensitivity of the photodetector is likely to change over time due to the influence of dust, oil, etc. adhering to the photodetector, and therefore there is a risk that accurate detection operation cannot be performed. Additionally, there is a problem in that the detection results vary depending on the color of the bobbin thread and the presence or absence of gloss.

This invention was made in consideration of the above circumstances, and its purpose is to reduce the influence of the type of bobbin thread and various types of dirt adhering to the detection device, and to reduce the influence of the type of bobbin thread and the presence or absence of glossiness of the bobbin thread. An object of the present invention is to provide a bobbin thread amount detection device for a sewing machine that can eliminate variations in detection results and perform accurate bobbin thread amount detection operations.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a thread loop catcher capable of forming stitches on a workpiece cloth in cooperation with a needle, and a thread ring catcher provided on a shaft portion around which the bobbin thread is wound and on both ends of the shaft portion. a bobbin that is removably attached to the thread ring catcher; an output device that is disposed on the thread ring catcher and outputs electromagnetic waves such as light; a passageway that is provided and allows the electromagnetic wave to pass between the detected portion made of the bobbin thread or the bobbin itself and the output device;
a plurality of detection devices that are arranged in the example of the thread ring catcher, input electromagnetic waves that are reflected by the detected portion after being output from the output device, and output detection signals according to the input signals; The apparatus further includes a determining means for determining whether the amount of bobbin thread at the shaft portion of the bobbin is equal to or less than a predetermined amount by calculating a ratio of detection signals output from each of the detection devices.

[Effect]

Magnetic waves such as light outputted from the output device pass through the passage of the thread ring catcher and are irradiated onto the detected part consisting of the bobbin thread or the bobbin itself, and the electromagnetic waves reflected by the detected part are sent to multiple detection devices. is input. Then, by calculating the ratio of the detection signals output from each detector according to the input signal, the determining means determines whether the amount of bobbin thread at the shaft portion of the bobbin is equal to or less than a predetermined amount.

〔Example〕

Hereinafter, a first embodiment of a bobbin thread amount detecting device for a sewing machine embodying the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, there is a thread loop catcher 3 in the bed section l of the sewing machine that passes through the throat plate 1a and forms a lock stitch on the workpiece cloth in cooperation with a needle 2 that can move up and down. It is arranged. The thread ring catcher 3 includes an outer hook 4 that is rotatable in synchronization with the vertical movement of the needle 2, and the outer hook 4 is formed with a tip 4a and a notch 4b. An inner pot 5 is held stationary within the outer pot 4. A bobbin case 6 is removably positioned and attached to the accommodation portion 5a of the inner pot 5, and a bobbin 7 is placed inside the bobbin case 6.
is attached removably and rotatably. The bobbin 7 includes a hollow shaft portion 7a around which the bobbin thread T1 as a detected portion is wound, and a pair of collar portions 7b provided at both ends of the hollow shaft portion 7a.

Further, as shown in FIGS. 1 and 2, an opening 8.9 is formed in the peripheral walls of the inner hook 5 and the bobbin case 6, which are substantially bent to each other and can face the notch 4b of the outer hook 4. A passage communicating between the inside and outside of the thread ring catcher 3 is formed by the notch 4b and each opening 8.9. On one side of the thread ring catcher 3, a support 10 is disposed in the bed portion 1, and on the support 10 is arranged opposite the opening 8.9 and parallel to the axis of rotation of the thread ring catcher 3. One light emitting element 11 serving as an output device is disposed in a substantially orthogonal plane. This light emitting element 11 has a case lla having a light transmitting part.
covered by.

Further, on one side of the light-emitting element 11, a pair of light-receiving elements 12 and 13 as a detection device are arranged in the plane and covered by a case 14 having a light transmitting part. still,
Each of the elements 11 to 13 is integrally provided with a lens at its tip.

Visible light of a specific wavelength emitted from the light emitting element 11 passes through each opening 8.9 and is irradiated onto the bobbin thread T1, and the reflected light is input to each light receiving element 12.13.

As shown in FIG. 3, the sewing machine of this embodiment is equipped with a microcomputer (
(hereinafter abbreviated as microcomputer) 15, the microcomputer 15
The determining means is constituted by: The light emitting element 11 is connected to the microcomputer 15 via a drive circuit 16. The light receiving elements 12.13 are connected to the microcomputer 15 via conversion amplifier circuits 18.19. and,
The reflected light from the bobbin thread T1 is converted into an electric signal by the light receiving element 12.13, and then converted into an electric signal by the conversion amplifier circuit 18.19.
After being subjected to current-to-voltage conversion, the signal is amplified and output to the microcomputer 15 as a detection signal corresponding to the amount of input light.

Further, an alarm output circuit 20 is connected to the microcomputer 15. Furthermore, the microcomputer 15 includes an adjuster 21 for finely adjusting a predetermined reference value based on the distance between the hollow shaft portion 7a of the bobbin 7 and each element 11, 12, 13, and inputting it to the microcomputer 15. It is connected.

Now, in the above sewing machine, the thread wheel catcher 3 is rotated in synchronization with the vertical movement of the needle 2, so that the upper thread T2 inserted through the needle 2 and the thread wheel catcher 3 are paid out from the bobbin 7. A lock stitch is formed on the work cloth C by the bobbin thread T1.

On the other hand, based on the control of the microcomputer 15, the light emitting element 11 is activated via the drive circuit 16, and a spot light is emitted from the light emitting element 11 toward the bobbin 7 in the thread ring catcher 3. For example, in response to the position of the needle 2, the outer hook 4 is
The cutout portion 4b of the inner pot 5 and the bobbin case 6 each have openings 8,
9, the spot light emitted from the light emitting element 11 passes through the notch 4b and each opening 8, 9, and is irradiated onto the bobbin thread T1 on the bobbin 7, and the light reflected by the bobbin thread T1 is reflected by the bobbin thread T1. The light is inputted to each light receiving element 12.13 through each of the openings 8.9 and the notch 4b. When the notch 4b of the outer hook 4 does not coincide with each opening 8.9, the light reflected by the outer circumferential portion of the outer hook 4 is input to each light receiving element 12.13.

Each light receiving element 12, 13 inputs a detection signal corresponding to the amount of input light to the microcomputer 15 via each conversion amplifier circuit 18, 19. In response to this input, the microcomputer 15 calculates the ratio of the detection signals output from each of the light receiving elements 12 and 13,
The ratio is compared with a reference value set by the regulator 21. Based on the comparison results, microcontroller 15
When it is determined that the bobbin thread amount is less than a predetermined amount, the alarm output circuit 20 is activated to activate an alarm such as a buzzer or a lamp.

Here, to explain the detection principle, as shown in FIG. 6, there are two cases in which the detected part The reflection angle of the spot light emitted by the light emitting element 11 by the detected part X changes depending on the case where the light emitting element 11 is located at a position separated by the two-dot chain line. - Due to this change in the reflection angle, the incident position of the reflected light on each light receiving element 12.13 changes, and this change in the incident position causes a change in the ratio of the amount of human light on each light receiving element 12.13. This appears as a change in the ratio of the detection signal output from .13.

Therefore, since the ratio of the detection signals of the light receiving elements 12.13 corresponds to the distance between the light emitting element 11 and the detected part X, if the detected part X is replaced with the lower thread T1 on the bobbin 7, each light receiving element By determining the ratio of the detection signals of .13, the distance between the light emitting element 11 and the lower thread T1, that is, the remaining amount of the lower thread TI on the bobbin 7 can be determined. If the adjuster 21 sets a value corresponding to the ratio of the detection signals of each light receiving element 12.13 when the bobbin thread Tl is minimum as a reference value, the consumption status of the bobbin thread T1 can be determined. it is obvious.

As described above, the operator can easily confirm that the bobbin thread T1 needs to be replenished by operating the alarm. In this embodiment, a pair of light receiving elements 12
．． Since the bobbin thread amount can be detected based on the ratio of the detection signals output from the light receiving element 12 and 13, the detection sensitivity is less affected by dust, oil, etc. adhering to the light receiving element 12 and 13, compared to the detection operation using a single light receiving element. It is possible to perform accurate detection operations because there are fewer fluctuations due to Further, there is no possibility that the detection results vary depending on the color of the bobbin thread T1 or the presence or absence of gloss.

Next, a second embodiment embodying the present invention will be described, focusing on the differences from the first embodiment. As shown in FIGS. 4 and 5, a notch 31 is formed on the outer surface of the bobbin case 6, and a hollow shaft portion 7 of the outer flange 7b of the bobbin 7 is formed.
A plurality of openings 32 that can be arranged opposite to the notch 31 are formed near a. Then, the notch 3
1 and the opening 32 constitute a passage that communicates the inside and outside of the thread ring catcher 3. Further, within the bed portion 1, the cutout portion 31 is provided in a plane parallel to the rotational axis of the thread ring catcher 3.
A light emitting element 11 and light receiving elements 12 and 13 having the same configuration as in the first embodiment are arranged to face each other.

Therefore, in this embodiment, the light emitted from the light emitting element 11 passes through the cutout 31 of the bobbin case 6 and the opening 32 of the bobbin 7, and is introduced between the two flanges 7b.

While a predetermined amount or more of the bobbin thread T1 remains on the bobbin 7, the light reflected by the bobbin thread T1 passes through the opening 32 and the notch 31 and is manually applied to each light receiving element 12.13. As shown by the two-dot chain line in the figure, when the bobbin thread amount is less than a predetermined amount, the light from the light emitting element 11 reaches the inner flange 7b of the bobbin 7, and the light reflected by the flange 7b is is input to each light receiving element 12.13. That is, in this embodiment, the detected portion is constituted by the bobbin thread T1 and the inner flange portion 7b.

Therefore, each element 11 to 13 and the inner flange 7b of the bobbin 7
The reference value determined according to the interval between
By comparing the ratio of the output from each light receiving element 12, 13 calculated by 5, it is possible to accurately detect that the bobbin thread amount has become less than a predetermined amount, similarly to the embodiment described above.

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, each element 11, 12,
A plurality of lenses facing each other may be attached to the lens 3, and a fiber for optical transmission may be provided between each lens and each element 11 to 13. Furthermore, instead of the visible light, it is also possible to use an output device and a detection device that can input and output infrared rays.

〔Effect of the invention〕

As described in detail above, this invention reduces the influence of the type of bobbin thread and various types of dirt that adhere to the detection device, and eliminates variations in detection results caused by the color and presence or absence of gloss of the bobbin thread, thereby providing accurate results. This provides an excellent effect of being able to perform a bobbin thread amount detection operation.

[Brief explanation of the drawing]

1 to 3 show a first embodiment embodying the present invention, FIG. 1 is a front view showing a thread ring catcher and a bobbin thread amount I feeding device, and FIG. 2(a) is an inner view. FIG. 2(b) is a side view of the hook, FIG. 2(b) is a side view of the bobbin case, and FIG. 3 is a block diagram showing the control device of the bobbin thread amount detection device. 4 and 5 show a second embodiment, in which FIG. 4 is a side sectional view of the sewing machine, and FIG. 5 is a plan sectional view showing a thread loop catcher and a bobbin thread N detection device. 6th
The figure is an explanatory diagram showing the detection principle. 2... Needle, 3... Thread ring catcher, 4b... Notch,
7... Bobbin, 7a... Hollow shaft portion, 7b... Flange portion, 8.9... Opening (a passage is constituted by the above-mentioned 4b and 8.9), 11... Output device Light-emitting element as 12.13... Light-receiving element as detection device, 15
... Microcomputer as a determination means, 31 ... Notch,
32...Opening (a passage is constituted by the above-mentioned 31.32), C...Working cloth, T1...Bobbin thread. Patent applicant: Brother Industries, Ltd. (b) (a)

Claims (1)

[Claims] 1. A thread loop catcher (3) capable of forming stitches on the work cloth (C) in cooperation with the needle (2), and a shaft portion (on which the bobbin thread (T1) is wound); 7a) and a pair of flanges (7b) provided at both ends of the shaft.
a bobbin (7) that is removably attached to the thread ring catcher (3); an output device (11) that is arranged on one side of the thread ring catcher (3) and outputs electromagnetic waves such as light; 3)
a passage provided in the lower thread (T1) or the bobbin (7) itself that allows the electromagnetic waves to pass between the detected section and the output device (11); and the thread ring catcher (3). A plurality of detection devices (12, 13) and the ratio of the detection signals output from each of the detection devices (12, 13) to determine whether the bobbin thread amount at the shaft portion (7a) of the bobbin (7) is less than or equal to a predetermined amount. A bobbin thread amount detecting device for a sewing machine, comprising a determining means (15) for determining whether the bobbin thread amount is the same or not.