JPS605316B2 - Thread breakage detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting thread breakage, such as bobbin thread breakage in an automatic sewing machine, and is particularly designed to be able to perform reliable detection with a simple configuration.

Conventional devices of this type include those in which a thread is threaded through one side of an arm that is biased to one side, and the arm moves to detect when the thread runs out, or a device in which a light emitter and a light-receiving element are installed on both sides of the thread running path. In some cases, when the thread is present, the light emitter and the light-receiving element are blocked, and when the thread is missing, light enters the light-receiving element and is detected.

However, in the case of these devices, those that use an arm physically apply force to the thread, which is undesirable. In addition, in the case where a light emitting body and a light receiving element are provided on both sides of the thread, the running path of the thread is not necessarily stable, resulting in false detection when the running path changes, and dust etc. may adhere to the surfaces of the light emitter and light receiving element. In this case, the light may be blocked and thread breakage may not be detected. In view of these points, the present invention is designed to ensure thread breakage can be detected with a simple configuration. An embodiment of the present invention will be described below with reference to the drawings. In the drawings, FIG. 1 is a plan view of the device seen from below, and 1 is a throat plate, 2 is a thread path, 3 is a hole provided in the thread path 2,
4 indicates a lower thread inserted through hole 3.

Further, reference numerals 5 and 6 indicate light guides made of optical fibers, etc., and one end of these light guides 5 and 6 is connected to the side surface of the hole 3, respectively, and a light emitter 7 is provided at the other end of the light guide 5. A light receiving element 8 is provided at the other end of the light guide 6. Furthermore, FIG. 2 is a sectional view of the apparatus, and in the figure, only the main parts are shown enlarged for explanation.

In the figure, a notch 9 is provided in a part of the lower surface of the thread path 2,
One end of the light guide 5 is inserted into the notch 9, so that the end surface of the light guide 5 faces the side surface of the hole 3. Although not shown, the light guide 6 is similarly inserted into the notch so that its end face faces the side surface of the hole 3. Also, 10 is a needle, 11
is a needle thread, 12 is a cloth, and 13 is a hook. In these figures, light from the light emitter 7 is irradiated through the light guide 5 toward the inner surface of the hole 3 from this end surface.

Here, the light guides 5 and 6 are arranged so that the light emitted from one end of the light guide 5 does not directly enter the light guide 6, and in the illustrated example, they are provided at positions 90 degrees apart from each other. When the bobbin thread is present in the hole 3, light emitted from one end of the light guide 5 is diffusely reflected by the fluff of the bobbin thread 4, and this reflected light is incident on one end of the light guide 6. This light is irradiated onto the light receiving element 8 via the light guide 6. Therefore, in this device, when the bobbin thread 4 is present, the light receiving element 8 detects light, and when the bobbin thread 4 is missing, the light receiving element 8 cannot detect light.

When the light is no longer detected, it is determined that a thread breakage has occurred, and a lamp can be turned on or an alarm can be sounded. In this way, the presence or absence of the bobbin thread (thread breakage) is detected.According to the present invention, the diffusely reflected light due to the fluff of the bobbin thread 4 is detected, so the running path of the bobbin thread 4 changes somewhat. It is possible to perform detection reliably even if the

In addition, thread breakage is detected when the reflected light disappears, so even in the event of an accident such as when the light emitter 7 is turned off, the action is taken to detect thread breakage, and accidents can be minimized. . Furthermore, since the detection is performed inside the hole 3 of the thread path 2,
The running path of the bobbin thread 4 is relatively stable and is not easily affected by disturbances such as incidence of external light.

In addition, by setting the diameter of the hole 3 to, for example, a diameter of about 2 mm, the loop of the bobbin thread 4 rubs against the inner surface of the hole 3, and dust etc. are prevented from adhering to the end surfaces of the light guides 5 and 6. Prevented.
In the above example, when the needle 10 is inserted into the hole 3, the light guide 6 is no longer irradiated with light, and there is a risk that thread breakage will be erroneously detected. It is also possible to select a detection period based on the above information and prevent protection detection from occurring.

Furthermore, this detection circuit (not shown), the light emitting body 7, the light receiving element 8, etc. may be arranged in parallel on the throat plate 1, thereby making it extremely easy to attach this device to a sewing machine or the like. . Furthermore, by painting the inner surface of the hole 3 with black paint or the like to make it non-reflective, detection can be made more reliable.

Furthermore, in manufacturing this device, it is sufficient to first form a notch 9 on the lower surface of the thread path 2, attach it to the throat plate 1, and then provide the light guides 5, 6, etc., and the configuration is simple. At the same time, manufacturing is also extremely easy.

Note that the present invention is applicable not only to automatic sewing machines but also to various devices such as spinning machines and rounding machines.

Further, the present invention is not limited to the above-mentioned example, and various modifications are possible.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an example of a thread breakage detection device according to the present invention, viewed from below, and FIG. 2 is a sectional view thereof. 1 is a throat plate, 2 is a thread path, 3 is a hole, 4 is a lower thread, 5 and 6 are light guides, 7 is a light emitter, and 8 is a light receiving element. Figure 1 Figure 2

Claims (1)

[Claims] 1. A small diameter hole is provided through which the thread is inserted, one end of a first light guide is provided on the side surface of this hole, and light is irradiated toward the inner surface of the hole through this first light guide. In addition, one end of a second light guide is provided on the side surface of the hole at a position where the light from the first light guide is not directly incident, a light receiving element is provided at the other end of the second light guide, and a light receiving element is provided at the other end of the second light guide. A thread breakage detection device, wherein a light receiving element detects light from the first light guide reflected by the thread inserted through the hole.