JPS6136958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fabric edge detection device for a sewing machine, and particularly to improvements thereof.

Generally, in a fabric edge detection device for a sewing machine, for example, a light emitting means is provided on the arm of the sewing machine, a light receiving means is provided on the needle plate, and a space between the light emitting means and the light receiving means is placed on a table (or sewing machine bed). It is well known that the edge of the cloth is detected by blocking or opening the cloth.

However, as shown in Figure 1, when sewing pocket fabric W ₂ onto fabric W ₁ , the edge of fabric W ₂ is detected and the distance d between the end point of seam line M and the edge of the fabric is automatically controlled. In this case, since the throat plate is always covered by the cloth _W1 , the cloth edge detection device configured as described above cannot be used. Therefore, for such a case, a cloth edge detection device having the configuration shown in FIGS. 2 and 3 was devised. That is, in the figure, 2 is a table, 3 is a needle, 4 is a presser foot, 5 is a light emitting means, 6 is a light receiving means, and 7 is a reflecting plate for reflecting the light from the light emitting means to enter the light receiving means. , is fixed to the cloth presser bar at a distance above the table in front of the presser foot 4 in the cloth feeding direction. And cloth W ₁
When sewing the cloth W ₂ , the cloth W ₁ is moved between the reflective plate 7 and the table 2, and the side edge of the cloth W ₂ is moved on the reflective plate 7, and the presence or absence of the cloth W ₂ is determined. When the upper surface of the reflecting plate 7 is exposed, the light from the light emitting body 5 enters the light receiving body 6 through the reflecting plate 7, so that the light receiving body 6 is operated and, for example, control such as stopping the sewing machine is performed.

However, in such a configuration, the cloth W ₁ ,
Since the reflective plate is interposed between W ₂ , it obstructs the feeding operation of _the cloths W ₁ and W ₂ and reduces the operability. In order to adjust the distance d, it is necessary to configure the reflector plate 7 to be movable by manual operation, which is extremely troublesome.

The present invention has been made in view of the above-mentioned conventional drawbacks, and provides a fabric edge detection device that can detect the fabric edge of the upper fabric in a two-layered fabric using only optical means without directly contacting the fabric. The purpose is to provide the following.

Hereinafter, embodiments of the present invention will be described based on the drawings, and the same components as those of the above-mentioned conventional system will be designated by the same reference numerals and the description thereof will be omitted. Now, in FIG. 4, reference numeral 8 is a lamp that emits white light, and it is illuminated diagonally above the table 2 (or throat plate) in front of the presser foot 4 in the cloth feed direction. Fix it to the lower end of the jaw of machine frame 1 of the sewing machine. Reference numeral 9 denotes a fixed image sensor fixed to the front surface of the machine frame 1, and as shown in FIG. By arranging S ₁ to Sn on a semiconductor substrate and sequentially applying a pulse voltage to each photosensitive cell, it is detected whether each photosensitive cell S ₁ to Sn is irradiated with light of a certain level or higher. Ru.
Note that CCD (charge coupled semiconductor optical sensor), MOS (metal oxide semiconductor optical sensor), CID (charge injection semiconductor optical sensor), etc. are known as solid-state image sensors, and in this example, any one of them is used. May be used with those of

10 is a convex lens fixed to the machine frame 1 so as to be interposed between the table 2 and the solid-state image sensor 9, and focuses the image of light on the table 1 onto the photosensitive cells S ₁ to Sn of the solid-state image sensor 9. Set its placement as follows to make it look like this: That is,
If the focal length of the convex lens 10 is f, the distance from the table 2 to the convex lens 10 is _l1 , and the distance from the convex lens 10 to the solid-state image sensor 9 is _l2 , then in order for the above conditions to hold, f, _l1 , l ₂ must satisfy the formula 1/l ₁ +1/l ₂ =1/f, and thus, l ₂ =fl ₁ /l ₁ -f is set.

Next, the cloth edge detection operation in this embodiment will be explained.

First, the fabric W ₁ is placed on the table 2 so as to pass the lower surface of the presser foot 4, and then the fabric W ₂ is placed so that the rear edge Wz is located further back than the presser foot 4 in the cloth feeding direction. Then, insert it between the cloth W ₁ and the presser foot 4 (Fig. 4). Then, since the lamp 8 is located diagonally above the trailing edge Wz of the cloth W ₂ in the cloth feeding direction, the illumination F of the lamp 8 causes the cloth W ₁ to be placed on the cloth W 1 backward in the cloth feeding direction from the trailing edge Wz. To the side, posterior edge Wz
A shadow B is produced (Fig. 5).

Now, the distance d between the end of the stitch and the rear edge Wz of the cloth _W2 is set as follows.

That is, as shown in _FIG .
(smaller than R in the figure), the image of the shadow B of the rear edge Wz by the lamp 8 is condensed by the convex lens 10 through the optical path _P1 , and is projected onto the photosensitive cell Sl as shown in FIG. be projected. Since the level of light incident on the photosensitive cell Sl among the photosensitive cells S ₁ to Sn decreases, the photosensitive cell Se becomes the dark (L) level in the solid-state image sensor 9 as shown in FIG. 11, while the other photosensitive cells S ₁ ~Sl−1, Sl+1~
Sn remains at the bright (H) level because it is illuminated by the reflected light from the lamp 8 on the surfaces of the cloths W ₁ and W ₂ that is focused by the convex lens 10 . Therefore, the photosensitive cell S ₁ ~
An electronic control circuit (not shown) is programmed to stop the sewing machine motor when the condition of Sn shown in FIG. 11 is detected.

Now, after completing the above settings, the upper and lower cloth
Set W ₁ and W ₂ as shown in Figure 6 and start the sewing machine. Then, the needle 3 starts to move up and down, and the fabric feed means (not shown) moves the fabric up and down.
W ₁ and W ₂ are transported in the direction of arrow A. At this time,
Since the cloth edge Wz does not exist within the region R, the shadow B (FIG. 5) of the cloth edge Wz is the solid-state image sensor 9.
Therefore, the photosensitive cell S ₁ ~
Since Sn is all at H level as shown in FIG. 9, there is no command to stop the sewing machine motor.

Next, when the upper and lower cloths W ₁ and W ₂ reach the position shown in FIG.
The shadow B of Wz is projected onto the photosensitive cell Sl- ₄ through the optical path P2 as shown in Fig. 8, and the photosensitive cells _S1 to Sn are in the state shown in Fig. 10, but since the photosensitive cell Sl is not at the L level. The sewing machine motor has not yet been commanded to stop. Further, when the upper and lower cloths W ₁ and W ₂ are moved in the direction of the arrow, the projected image of the shadow B on the solid-state image sensor 9 moves in the opposite direction of the arrow A, and the upper and lower cloths W ₁ ,
When W ₂ reaches the position shown in FIG. 4, the shadow B of the cloth edge Wz by the lamp 8 is projected onto the photosensitive cell Sl via the optical path P ₁ as shown in FIG _.
Sn is in the state shown in Figure 11, and the control circuit is activated to command the sewing machine motor to stop, and the distance between the end of the stitch and the trailing edge Wz of the fabric _W2 is set to d. .

The set value of the distance d between the end of the seam and the rear edge Wz of the cloth W ₂ is determined by the value x input using a predetermined digital switch (not shown) using a microcomputer, and the focal length f of the convex lens 10. This can be set by calculating the distance l ₁ between the concave lens 10 and the table 2 as parameters, and specifying the photosensitive cell that should detect the above-mentioned L level.

Furthermore, in the above embodiment, the solid-state image sensor 9
Although only one is arranged, for example, by arranging only two in parallel to the cloth feeding direction, it is possible to correspond to one needle stop control of a two-needle sewing machine, etc.

Further, although the above embodiment uses a solid-state image sensor as the light receiving means, a phototransistor, a photodiode, etc. may also be used.

Furthermore, instead of white light, the light irradiated by the lamp 8 may be specific visible light such as red, blue, or green, or infrared light depending on the color of the fabric or the wavelength of the light detected by the light receiving means.

In addition, in the above embodiment, only the rear edge of the cloth is detected, but for example, another lamp may be irradiated diagonally above the front edge of the cloth in the cloth feeding direction as follows. Alternatively, a shadow may be created extending forward in the cloth feeding direction from the front edge of the cloth, and the sewing machine motor may be activated when this shadow is detected by the light receiving means.

Furthermore, by detecting the edge of the fabric, not only starting and stopping of the sewing machine motor may be controlled, but also thread trimming and reverse stitching may be controlled.

In addition, in the above embodiment, the shadow on the edge of the cloth is detected, but for example, if a black sticker is placed on the edge of the cloth,
Or, conversely, attach a sticker that easily reflects light.
The reflected light from this seal may be detected.

Furthermore, in the above embodiment, the case where the edges of the upper fabric are shifted from the edges of the lower fabric, such as pocket stitching, is shown, but this embodiment can also be applied to normal sewing in which the edges of the upper and lower fabrics are aligned. Of course, it can be applied.

As described above, according to the present invention, light is irradiated onto the fabric from the machine frame, and a shadow appearing on the edge of the fabric and an image of its reflection are projected onto the light receiving means using a convex lens, thereby detecting the edge of the fabric. Since the fabric edge detection function can detect the edge of the fabric without directly touching the fabric even during pocket sewing as shown in Figure 1, the fabric edge detection operation does not interfere with the fabric feeding operation, making it easier to The operability of thread sewing can be improved.

In addition, we do not use a reflective plate fixed to the machine frame, and the distance from the end of the seam to the edge of the fabric is set using the numerical value in the control circuit program, so even if the shape of the fabric etc. It is only necessary to change , and the versatility can be significantly increased.

[Brief explanation of the drawing]

Figure 1 is a diagram showing pocket sewing, Figures 2 and 3 are diagrams of conventional cloth edge detection operation, Figure 4 is a diagram of the cloth edge detection device of this embodiment, and Figure 5 is a diagram showing a shadow on the cloth edge. Figures 6 and 7 are diagrams of the resulting state, Figures 6 and 7 are diagrams of the cloth edge detection operation in this example, Figure 8 is a diagram of the state in which light is projected onto the photosensitive cell by the convex lens, and Figures 9 to 11 are diagrams of the state in each state. It is a figure which shows the H/L state of photosensitive cells S1 _-Sn . W ₁ , W ₂ ... cloth, 1 ... machine frame, 2 ... table, 3 ... needle, 8 ... irradiation means (lamp), 9 ...
...Light receiving means (solid-state image sensor), 10...Convex lens.

Claims (1)

[Claims] 1. Light can be irradiated from diagonally above to a predetermined range in the cloth feeding direction on the cloth feeding surface so as to generate shadows on uneven portions of the cloth on the cloth feeding path before the needle in the cloth feeding direction. A plurality of photosensitive cells are arranged in an area of a predetermined length along the fabric feeding direction above the fabric feeding path, and each photosensitive cell changes in bright and dark states depending on the presence or absence of a specific level of light. A light-receiving means that generates one of the signals, and a light-receiving means arranged between the cloth-feeding surface and the light-receiving means, transmitting light reflected from the cloth-feeding surface in a predetermined range in the cloth-feeding direction to an area of the light-receiving means having a predetermined length in the cloth-feeding direction. A fabric edge detection device for a sewing machine, comprising: a light collecting means that collects light and projects it onto a light receiving means; and a control circuit that controls electrical operation of a sewing machine mechanism based on the output of each photosensitive cell of the light receiving means.