JPH0142711B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a zigzag sewing machine, and particularly to a zigzag sewing machine, in which a seam line (a line consisting of a plurality of seams) is separated by a predetermined distance from the edge of a processed cloth (referred to as a cloth edge). The present invention relates to a cloth edge copying sewing machine that can form a fabric.

BACKGROUND OF THE INVENTION A zigzag sewing machine capable of sewing fabric edges is already known from US Pat. No. 4,248,168. This is because the position of the side edge of the work cloth is detected by a side edge detector, and the swinging position of the sewing needle is controlled based on the detection signal, so that a seam line is formed at a certain distance from the edge of the cloth. It is something that will be done. The seam allowance is automatically kept constant.

By utilizing the characteristic of the zigzag sewing machine that the swing position of the sewing needle, that is, the position in the direction perpendicular to the feed direction of the workpiece cloth, can be changed, it is possible to adjust the position of the sewing needle by adding simple devices such as a side edge detector. A sewing machine capable of copy stitching can be obtained.

Problems to be Solved by the Invention However, in conventional sewing machines of this type, there are two methods: from copy stitching with a constant seam allowance along the side edge of the work cloth to sewing with the same seam allowance along the edge that intersects with the side edge. There was a problem in that it was difficult to shift to copy stitching. Copy stitching is suitable for sewing collars and sleeves of shirts, for example, but in these areas the edges of the fabric intersect at right or acute angles, and it is difficult to sew any of these intersecting edges. It is also necessary to perform copy stitching with the same seam allowance.
To perform this kind of sewing, one edge (side edge)
When the end point of the seam line reaches a position inside the other edge by the seam allowance, stop the sewing machine and rotate the workpiece cloth by 90 degrees or more. It is necessary to restart the copy stitching after setting the edge so that the edge becomes the side edge. However, it is not easy for the operator to visually measure the distance between the end point of the seam line, that is, the drop point of the sewing needle, and the edge of the workpiece cloth, and to stop the sewing machine when the distance becomes equal to the seam allowance. It was either too long or too short, making it difficult to beautifully finish the intersections of seam lines along the mutually intersecting edges of the work cloth.

Means for Solving the Problems In order to solve the above problems, the present invention provides a sewing needle capable of vertical reciprocating movement and lateral rocking movement;
A zigzag sewing machine equipped with a feeding device that applies feeding motion to the work cloth in synchronization with the up and down reciprocating movement of the sewing needle, and a needle swing control motor that controls the swing position of the sewing needle to change the stitch forming position. (a) a side edge detector that detects a side edge extending in the feed direction of the work cloth and generates a side edge position signal regarding the position of the side edge in the swinging direction of the sewing needle; and (b) a side edge detector that detects the side edge extending in the feed direction of the work cloth; (c) an edge detector that detects an edge extending in a direction intersecting with the feed direction and generates an edge position signal regarding the position of the edge in the feed direction; a seam allowance setting means having a manually operable operation section for setting the seam allowance up to the seam forming position and generating a seam allowance setting signal regarding the set seam allowance; and (d) swinging of the sewing needle. a needle swing control means for controlling a needle swing control motor in accordance with a side edge position signal and a seam allowance setting signal so that the needle swing control motor is positioned at a position separated by a set seam allowance from the side edge of the work cloth; ) such that the edge detector detects the position of the edge on an extension line of a seam line formed parallel to the side edge of the work cloth and separated from the side edge by a set seam allowance; detection position changing means for changing the detection position of the detector in the swinging direction of the sewing needle in conjunction with the operation of the operating section;
(f) Feed control means for controlling the operation of the feed device according to the edge position signal and the seam allowance setting signal so that the edge of the work cloth reaches a position separated by a set seam allowance from the dropping point of the sewing needle. It has been established that

In a preferred embodiment of the present invention, the edge detector includes a reflective surface on the sewing machine bed, a photo sensor having a light emitting element that emits light toward the reflective surface, and a light receiving element that receives light reflected from the reflective surface. The photo sensor is installed so as to be rotatably adjustable around a fixed axis on the sewing machine frame parallel to the feeding direction of the feeding device.

Functions and Effects In the fabric edge copy stitch sewing machine according to the present invention,
When copy sewing is performed with a constant seam allowance along the side edge of the workpiece cloth, the feed control means feeds according to the edge position signal from the edge detector and the seam allowance setting signal from the seam allowance setting means. The operation of the device is controlled so that the edge of the workpiece cloth reaches a position separated by the seam allowance from the point where the sewing needle drops. Therefore, the operator does not have to manually finish copy stitching along the side edge of the workpiece cloth by visually measuring the distance between the dropping point of the sewing needle, that is, the end point of the seam line, and the edge of the workpiece cloth. It becomes easy to beautifully finish the intersection of the tracing stitches along the side edges and the tracing stitches along the end edges.

Moreover, when the operation part of the seam allowance setting means is operated to change the seam allowance, the detection position of the edge detector in the needle swing direction is also changed by the detection position changing means in conjunction with the operation, and the edge edge is always detected on the extension of the seam line along the side edge, so even if the edge is not perpendicular to the side edge, the profile stitch along the side edge will end exactly a distance equal to the seam allowance inside from the edge. I am made to do so. If the edge is not perpendicular to the side edge and the edge is detected at a position other than the extension of the seam line, the following formula Δ=L・tanθ Where, L: Distance θ from the extension of the seam line to the detection position : An error Δ expressed as the angle that the edge makes with respect to a straight line perpendicular to the seam line occurs, but in the sewing machine according to the present invention, the distance L is always maintained at 0, so such a detection error does not occur.
Therefore, even if the edge is not perpendicular to the side edge,
The effect of creating a beautiful finish at the intersection of the tracing stitch line along the side edge and the tracing stitch line along the end edge can be obtained.

Particularly, in a desirable embodiment in which the edge detection position is maintained on the extension line of the seam line by rotating the photo sensor around a fixed axis parallel to the cloth feeding direction, the present invention has a simple structure and is inexpensive. You can obtain unique effects that can help you achieve your goals.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

As shown in FIG. 2, the sewing machine of this embodiment has a bed 10 with a flat top surface, a pillar part 12 rising from the right end of the bed 10, and a cantilevered part from the upper end of the pillar part 12. The sewing machine frame 16 includes an upper arm 14 extending substantially parallel to the bed 10. Head 18 at the free end of the upper arm 14
is provided with a start/stop switch 20 for controlling starting and stopping of the sewing machine motor, which is the main driving source of the sewing machine, and the upper arm 14 further has shapes representing a plurality of types of stitch patterns that can be formed by this sewing machine. A display board 22 and a pattern selection switch 24 that is operated to select a stitch pattern are provided. Further, the pillar portion 12 is provided with a copying stitch switch 26 that is operated to perform copying stitching of the cloth edge.

FIG. 3 shows a state in which the cover of the head 18 is removed, and a needle bar stand 36 is attached to a protrusion 34 fixed to the sewing machine frame 16 by a shaft 38 so as to be swingable in a vertical plane. There is. A needle bar 40 is attached to the needle bar stand 36 so as to be slidable in the vertical direction, and a sewing needle 42 is fixed to the lower end of the needle bar 40. The needle bar 40 is connected to a sewing machine motor via a needle bar holder 44, etc., and the needle bar 40 and sewing needle 42 are caused to reciprocate up and down by driving the sewing machine motor. A needle swing control motor (not shown) is connected to the needle bar stand 36 via a Z link 46, etc., and the needle swing control motor causes the needle bar stand 36 to swing. Sewing needle 42
The lateral rocking position of the can be changed within a certain range.

Two photo sensors 48 and 50 are fixed to the lower part of the head 18, and reflective surfaces 54 and 56 are formed on the needle plate 52 on the bed 10 directly below the photo sensors 48 and 50, respectively.
The photo sensor 48 includes a light emitting element 58 that emits infrared rays toward a reflecting surface 54, as shown in FIG. 4a.
and a light-receiving element 60 that receives the infrared rays reflected by the reflective surface 54, and a holder 62 that holds the light-emitting element 58 and the light-receiving element 60.
and a signal processing circuit (not shown). Further, an optical filter 64 is provided immediately before the light receiving element 60, which allows infrared rays to pass through but blocks light of other wavelengths. The light-emitting element 58 and the light-receiving element 60 are arranged at a short distance apart in the lateral direction, that is, on a straight line parallel to the swinging direction of the sewing needle 42, and the reflective surface 54 is an arcuate surface passing through the midpoint P between them. ing. Therefore, this midpoint P and the reflective surface 54
A straight line connecting any one point Q above is perpendicular to the reflecting surface 54, and bisects the angle θ formed by the straight line connecting the light emitting element 58 and point Q and the straight line connecting the light receiving element 60 and point Q. Therefore, the light emitted from the light emitting element 58 toward the point Q will accurately reach the light receiving element 60.
It is reflected towards. As a result, the light emitting element 58
Although it is an inexpensive product with a very narrow range of linearity, as shown in FIG. 4b, the distance x from an arbitrary reference position to the side edge of the workpiece cloth 66
The effective detection range in which a linear relationship is established between the output voltage V of the photo sensor 48 and the output voltage V of the photo sensor 48 is widened. The photo sensor 48 and the reflective surface 54 constitute a side edge detector that detects the position of the side edge of the work cloth 66.

The photo sensor 50 has the same structure as the photo sensor 48 described above, but its light emitting element and light receiving element are arranged along a straight line perpendicular to the swing plane of the sewing needle 42, and processing in a direction parallel to the straight line is possible. The position of the edge of the cloth is detected.
The photo sensor 50 and the reflective surface 56 constitute an edge detector. Further, while the side edge detection photo sensor 48 is fixed to the sewing machine frame 16, the edge edge detection photo sensor 50 is rotatable around a fixed axis perpendicular to the swing plane of the sewing needle 42. has been done. That is, the photo sensor 5
Shafts concentrically protrude from both end faces of the sewing machine frame 16, and these shafts are rotatably supported by the yoke portion 68 of the sewing machine frame 16. A knob 70 is fixed to one of the shafts, and a potentiometer 72 is connected to the other. Rotation of the knob 70 causes the photo sensor 50 to rotate, and an output signal corresponding to the rotation angle is output. It is designed to be output from a potentiometer 72. The reflective surface 56 is curved along an arc centered on the center point between the light emitting element and the light receiving element of the photo sensor 50, but at the same time, it is also curved along an arc centered on the rotational axis of the photo sensor 50. As a result, it has an almost spherical shape.

The throat plate 52 has a transversely long needle hole 74 formed therein and a plurality of slots, through which a feed dog 76 can extend and retract. The feed dog 76 is provided with a feed motion synchronized with the vertical reciprocating movement of the sewing needle 42 by a sewing machine motor which is a common driving source with the sewing needle 42. A feed device is constituted by the feed dog 76, the sewing machine motor, and a link mechanism that connects the two.

Figure 1 shows the control device of this sewing machine. Although this control device is shown as a discrete circuit, it is also possible to configure the main part with a computer. The pattern selection switch 24 is shown at the left end of the figure. A pattern selection counter 80 is connected to the pattern selection switch 24, counts the number of times the pattern selection switch 24 is operated, and supplies the count to the stitch data generation device 82.
Further, although not shown, a plurality of light emitting diodes disposed on the display board 22 are made to emit light in accordance with the count contents, so that the selected stitch pattern is displayed.

The stitch data light emitting device 82 stores stitch data corresponding to each of the stitch patterns that can be formed, and selects stitch data corresponding to the count contents of the pattern selection counter 80 from among the stitch data. , feed data and needle swing data included in the selected stitch data are synchronized with the up and down reciprocating motion of the sewing needle 42 and are sent to the multiplexer 84 each time a timing pulse is supplied from the timing pulse generator 83. and 86 to the feed drive control circuit 88 and needle swing control circuit 90. The feed drive control circuit 88 controls the feed control motor 92 based on the supplied feed data. The feed control motor 92 drives a feed control mechanism provided in a link mechanism connecting the sewing machine motor and the feed dog 76, and adjusts the amount of feed given to the work cloth 66 by the feed dog 76. be. On the other hand, the needle swing control circuit 90 controls the needle swing control motor 94 based on the needle swing data, thereby controlling the sewing needle 42.
Change the swing position of.

With the above configuration, various stitch patterns are formed. When the copy stitch switch 26 is operated, the pattern selection counter 80 is reset in response to the rising edge of the output signal ET, and any stitch patterns that have been stitched up to that point are reset. Even if the stitch pattern is selected, the straight stitch remains selected. The output signal ET of the copying stitch switch 26 is supplied to the pattern selection counter 80 as well as to various parts of the control device as will be described in detail below, thereby putting the sewing machine in a state for copying.

The output voltage of the photo sensor 48 is converted into side edge data as a digital signal by an A/D converter 100.
The signal is converted into Dd and supplied to the adder 102. This adder 102 is also supplied with seam allowance data Dw from a seam allowance data memory 104. The seam allowance data memory 104 stores seam allowance data corresponding to the output signal of the potentiometer 72, and supplies various seam allowance data to the adder 102 in accordance with the operation of the knob 70. That is, the potentiometer 72 and the seam allowance data memory 104 constitute a seam allowance setting means, and the knob 70 functions as an operating section of the seam allowance setting means.

As described above, this knob 70 rotates the photo sensor 50 to change its detection position in the needle swing direction, so by rotating the knob 70, the set value of the seam allowance and the edge The needle swing direction of the edge detector, that is, the detection position in the direction perpendicular to the feed direction of the work cloth 66 changes in conjunction with each other, and the knob 70, potentiometer 72, and photo sensor 50 The connected shafts constitute the detection position changing means. In addition, it is possible to set the seam allowance by attaching a scale indicating the seam allowance to either the knob 70 or the yoke part 68, and attaching a reference line that indicates the set seam allowance together with the scale to the other side. This is desirable because it facilitates

The adder 102 is connected to the timing pulse generator 8.
A/D every time a timing pulse is supplied from 3.
Side edge data Dd supplied from the converter 100 and seam allowance data supplied from the seam allowance data memory 104
Dw is added to obtain needle position data Dp. The needle position data Dp follows the side edge data Dd with a difference of only the seam allowance data Dw. The multiplexer 86 is connected to the copying stitch switch 26
While the output signal ET is at a low level, the needle swing data supplied from the stitch data generator 82 is supplied to the needle swing control circuit 90 as described above, but when the output signal ET is high During the level, the needle position data Dp supplied from the adder 102 is supplied to the needle swing control circuit 90.

Seam allowance data Dw from seam allowance data memory 104
is also supplied to the comparator 106. This comparator 106 includes the photo sensor 50.
The comparator 106 is also supplied with edge data De obtained by converting the output voltage of the switch 26 into a digital signal by the A/D converter 107. That is, it operates only while the copy sewing is selected, and when the edge data De becomes equal to the seam allowance data Dw, a stop signal SP is supplied to the start/stop command circuit 108.
The start/stop command circuit 108 controls the sewing machine motor control device 110 in response to the operation of the start/stop switch 20.
However, when a stop signal is supplied from the comparator 106, a stop command signal is sent to the sewing machine motor control device 110 regardless of the operation of the start/stop switch 20. supply.

Edge data De from the A/D converter 107
is also supplied to another comparator 112. A deceleration start position setter 114 is also connected to this comparator 112, and the comparator 112 operates while the output signal of the copying stitch switch 26 is at a high level, so that the edge data De is greater than the deceleration start position setter Df. When the deceleration signal GS is sent to the sewing machine motor control device 1
Supply to 10. In this embodiment, the deceleration start position setter Df moves from the edge of the work cloth 66 to the reflective surface 5.
The comparator 112 outputs a deceleration signal GS to control the sewing machine motor in response to the photo sensor 50 detecting the edge of the work cloth 66 for the first time. It will be supplied to the device 110. The sewing machine motor control device 110 is always connected to the sewing machine motor drive circuit 11.
8, a high speed command signal is output for instructing the sewing machine motor 120 to rotate at high speed, but when the deceleration signal GS is supplied as described above, the state changes to a state in which a low speed command signal is supplied. Based on this low speed command signal, sewing machine motor drive circuit 118 decelerates sewing machine motor 120 to a speed at which it can be immediately stopped at any time.

The deceleration signal GS from the comparator 112 is also supplied to the multiplexer 84. While the deceleration signal GS is at a low level, the multiplexer 84 is in a state of supplying the feed data supplied from the stitch data generator 82 to the feed drive control circuit 88 as described above, but when the deceleration signal GS is at a high level. In this case, the minute feed data from the minute feed setting device 122 is supplied to the feed drive control circuit 88. The feed drive control circuit 88 drives the feed control motor 92 based on this minute feed data to reduce the amount of feed of the work cloth 66 by the feed teeth 76 to a predetermined minute amount.

As is clear from the above description, in this embodiment, the adder 102, the multiplexer 86, and the needle swing control circuit 90 constitute needle swing control means,
Comparator 106, start/stop command circuit 108, sewing machine motor control device 110, comparator 112, deceleration start position setter 114, sewing machine motor drive circuit 11
8, minute feed setting device 122, multiplexer 8
4. The feed drive control circuit 88 and the like constitute a feed control means.

In this sewing machine, when the copy stitch switch 26 is operated, the output signal ET is sent to the pattern selection counter 80, the multiplexer 86, and the comparators 106 and 11.
The sewing machine is then set to copy stitch mode.

Therefore, the operator operates the knob 70 to set the desired seam allowance, and places the work cloth 66 on the bed 10 with the position where the seam line is to be formed approximately in the center of the needle hole 68. When the start/stop switch 20 is operated, copy stitching is started. The sewing machine motor control device 110 rotates the sewing machine motor 120 at high speed via the sewing machine motor drive circuit 118, causing the sewing needle 42 to move up and down and reciprocating, giving a feed motion to the feed dog 76, and the needle swing control circuit 90 Needle position data Dp supplied from adder 102 via multiplexer 86
The needle swing control motor 94 is controlled based on this, and the swing position of the sewing needle 42 is controlled to a position separated from the side edge of the work cloth 66 by the seam allowance.

While copy stitching is being performed in this manner, the area of the reflective surface 56 that can be detected by the photo sensor 50 is completely covered by the work cloth 66;
As shown in FIG. 5, when the seam line 130 along the side edge 129 approaches the edge 132 of the work cloth 66, the reflective surface 5
6 emerges from the edge 132. As a result, the photo sensor 50 receives the infrared rays reflected by the reflecting surface 56, and the photo sensor 50 receives the infrared rays from the A/D converter 107.
12 becomes larger than the deceleration setting value Df of the deceleration start position setter 114,
A deceleration signal GS is supplied from comparator 112 to sewing machine motor control device 110 and multiplexer 84 .

Upon receiving this deceleration signal GS, the sewing machine motor control device 110 decelerates the sewing machine motor 120 to a predetermined speed via the sewing machine motor drive circuit 118 so as to be able to stop the sewing machine motor 120 at any time. The minute feed data from 122 is supplied to the feed drive control circuit 88. As a result, the sewing speed is reduced and the stitch pitch is reduced to a predetermined minute pitch.

In this state, after one or several stitches with minute pitches have been formed as shown in FIG. Seam allowance data supplied from allowance data memory 104
Dw, and the comparator 106 outputs a stop signal SP. In response to this stop signal, the start/stop command circuit 108 supplies a stop command signal to the sewing machine motor control device 110, and the sewing machine motor 120 is stopped. At this time, the sewing machine motor 120 is operated at a low speed that can be stopped immediately, and the stitch pitch is also small, so that the stitch line 130 is connected to the edge 130.
The tracing stitch along the side edge 129 is stopped when the seam is formed up to a point separated by a distance W ₂ exactly equal to the seam allowance W ₁ .

Therefore, the operator rotates the workpiece cloth 66 so that the end edge 132, which had previously extended in the horizontal direction, that is, in the swinging direction of the sewing needle 42, now extends in the front-rear direction, that is, in the feeding direction of the feed dog 76, and then switches the start/stop switch. 20 to start the sewing machine motor 120, copy stitching is performed along the previous edge 132 as a new side edge.

In this way, the copy stitching along the side edge 129 is automatically stopped at a point separated from the edge 132 by a distance W ₂ exactly equal to the seam allowance W ₁ , and in this state, the operator rotates the work cloth 66 . Since it is only necessary to move
It is easy to transition to copying stitching along line 2, and the intersection of the seam line 130 formed by both copying stitches is beautifully finished.

The case where the edge 132 of the work cloth 66 is orthogonal to the side edge 129 and the edge 132 extends in the needle swinging direction when the side edge 129 is scanned has been described above. Edge 13 as shown
2 may not be perpendicular to the side edge 129, and the end edge 132 may be inclined by an angle θ with respect to the needle swing direction while copy stitching is being performed along the side edge 129. According to this sewing machine, even in such a case, the tracing stitch along the side edge 129 is made from the end edge 132 with a seam allowance W ₁
is terminated at a position inside by a distance W ₂ equal to . This is because the detectable area 134 of the photo sensor 50 is always located on the extension line of the seam line 130, no matter what value the seam allowance _W1 is set. Now, if the edge detection position of the photo sensor 50 is fixed on the straight line 136 and the seam line 130 is formed at a position separated by a distance Y from the straight line 136, the edge 132 is defined by a dashed line. Side edge 1 when the position shown is reached
29, and the distance from the edge 132 to the end point of the seam line 130 becomes too small by Δ. However, in this sewing machine, the detectable area 134 of the photo sensor 50 is always Since it is located on the extension line of the seam line 130, the occurrence of such an error Δ can be avoided.

In this embodiment, the sewing machine motor 120 is stopped at the same time as the stop command signal is issued from the start/stop command circuit 108, but when the sewing needle 42 reaches the needle down position, the needle down position signal is A needle position detector that emits the signal is connected to the sewing machine motor control circuit 110 so that the sewing machine motor 120 is stopped when the needle down position signal is issued for the first time after the stop command signal is issued from the start/stop command circuit 108. It is also possible to do so. In this way, from the tracing stitch along the side edge 12 to the end edge 1
32, the work cloth 66 can be rotated around the sewing needle 42 passing through the work cloth 66, so that the intersection of the seam lines along both edges can be finished even more beautifully. becomes possible.

Further, in the embodiment, the photo sensor 5
In response to detecting the edge 132 for the first time, the sewing machine motor 120 is decelerated and the stitch pitch is reduced. When the edge 132 reaches a position a certain value larger than the set seam allowance, the sewing machine motor 12
It is also possible to perform a deceleration of 0, etc., and in this way, the number of stitches that are shorter than other stitches can be kept to the minimum necessary number regardless of changes in the seam allowance. can. However, the sewing machine motor 120
It is also possible to omit the speed reduction and/or the stitch pitch reduction itself.

Furthermore, as a side edge detector and an edge detector,
It is also possible to use a different type of detector such as a transmission type photo sensor. In this case, these transmission type photo sensors are disposed in a recess formed on the upper surface of the sewing machine bed 10, and the edge detection photo sensor is The position in the needle swing direction may be adjustable, and the setting value of the seam allowance may be changed in conjunction with the adjustment of this position.

In addition, the present invention can be practiced with various modifications and improvements based on the knowledge of those skilled in the art, such as changing the structure of the mechanism and control device of the sewing machine.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a control device for a fabric edge tracing sewing machine which is an embodiment of the present invention. FIG. 2 is a perspective view showing the external appearance of the fabric edge copy sewing machine, and FIG. 3 is a perspective view showing the sewing machine with the head cover removed. FIG. 4 is an explanatory diagram conceptually showing a photo sensor as a side edge detector and a reflecting surface in the sewing machine. FIG. 5 and FIG. 6 are explanatory diagrams showing the execution status of copy stitching by the sewing machine, respectively, and FIG. 7 is an explanatory diagram showing the execution status of copy stitching when the edge of the work cloth is not perpendicular to the side edge. It is. 42: Sewing needle, {48: Photo sensor, 54: Reflective surface} side edge detector, {50: Photo sensor, 5
6: Reflective surface} Edge detector, {70: Knob (operation unit), 72: Potentiometer, 104: Seam allowance data memory} Seam allowance setting means, 76: Feed dog (feed device), {84: Multiplexer , 88: Feed drive control circuit, 106: Comparator, 108: Start/stop command circuit, 110: Sewing machine motor control device, 11
2: Comparator, 114: Deceleration start position setter, 11
8: Sewing machine motor drive circuit, 122: Fine feed setting device} Feed control means, {86: Multiplexer,
90: Needle swing control circuit, 94: Needle swing control motor} Needle swing control means, 102: Adder, {12
9: Side edge, 132: End edge} Cloth edge, 130: Seam line.

Claims (1)

[Scope of Claims] 1. A sewing needle capable of vertical reciprocating motion and lateral rocking motion, a feeding device that imparts a feeding motion to a workpiece cloth in time with the vertical reciprocating motion of the sewing needle, and rocking of the sewing needle. In a zigzag sewing machine equipped with a needle swing control motor that controls the position and changes the stitch forming position, the side edge extending in the feed direction of the workpiece cloth is detected, and the position of the side edge in the swing direction of the sewing needle is detected. a side edge detector that generates a side edge position signal; and an edge detector that detects an edge of the work cloth that extends in a direction intersecting the feed direction and generates an edge position signal regarding the position of the edge in the feed direction. a detector; and an operation section that can be manually operated to set a seam allowance from an edge including a side edge and an end edge of the work cloth to a seam forming position, and a seam allowance related to the set seam allowance. seam allowance setting means for generating a setting signal; Therefore, the needle swing control means for controlling the needle swing control motor, and the edge detector are formed parallel to the side edge of the work cloth at a distance from the side edge by the set seam allowance. detection position changing means for changing the detection position of the edge detector in the swinging direction of the sewing needle in conjunction with the operation of the operating section so as to detect the position of the edge on the extension line of the stitch line; Feed control that controls the operation of the feed device according to the edge position signal and the seam allowance setting signal so that the edge of the workpiece cloth reaches a position separated by the set seam allowance from the point where the sewing needle drops. What is claimed is: 1. A fabric edge copying sewing machine characterized by being provided with means. 2. The edge detector includes a reflective surface on the sewing machine bed, a photo sensor having a light-emitting element that emits light toward the reflective surface, and a light-receiving element that receives the reflected light from the reflective surface, and the photo sensor is connected to the feeder. 2. The fabric edge copying sewing machine according to claim 1, wherein the sewing machine is rotatably installed around a fixed axis on a sewing machine frame parallel to the feeding direction of the device.