JPS62388A - Fabric edge copy sewing machine - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a zigzag sewing machine, and more particularly to a fabric edge copy stitch sewing machine that forms a seam line at a predetermined distance from the side edge (referred to as a fabric edge) of a workpiece fabric. It is related to.

A conventional zigzag sewing machine includes a sewing needle capable of vertical reciprocating motion and horizontal swinging motion, a stitch forming mechanism driven by a sewing machine motor, and a needle swing control motor that controls the swinging position of the sewing needle. , the stitch formation position can be changed by the lateral swing movement of the sewing needle. This zigzag sewing machine capable of sewing fabric edges is disclosed in U.S. Patent No. 4,248.
．． It is already known from the specification No. 168. The position of the edge of the fabric is detected by a fabric detector consisting of a transmission type photosensor, and the lateral position of the sewing needle is controlled based on the detection signal to form a seam line at a fixed distance from the edge of the fabric. It is something that

If you take advantage of the zigzag sewing machine's ability to change the horizontal position of the sewing needle, that is, the position perpendicular to the feed direction of the workpiece fabric, you can sew fabric edges by adding simple devices such as a fabric detector. You can get a sewing machine that is possible.

Problems to be Solved by the Invention However, conventional fabric edge tracing sewing machines of this type have the following problems:
Even though the distance between the fabric edge and the seam line, that is, the seam allowance, is not maintained at a predetermined value, the operator may continue sewing without noticing this, and even if the operator notices it, the sewing speed, i.e. Since the feeding speed of the workpiece cloth is high, the position of the workpiece cloth cannot be corrected in time, which causes a problem in that the seam allowance deviates from a desired value.

While fabric edge copy sewing is being performed, if the positional fluctuation of the fabric edge is kept within the maximum swing range of the sewing needle, the seam allowance is automatically maintained at a predetermined value. Normally, the maximum swing range of the sewing needle is not so wide, for example, 7III11, so the amount of variation in the fabric edge position exceeds the maximum swing range of the sewing needle, making it impossible to control the needle position and reducing the seam allowance. There is a possibility that it will not be maintained at a predetermined value.

In addition, if the operator notices that such a situation is likely to occur, he or she may rotate the work cloth by a small angle around the needle drop point, that is, the intersection of the center line of the sewing needle and the top surface of the throat plate. Therefore, it is necessary to return the position of the sewing needle toward the center of the maximum swing range, but if the feed speed is high, the position of the work cloth cannot be corrected in time;
When the sewing needle reaches the end of its maximum swing range, it becomes impossible to control the needle position, and the seam allowance deviates from a predetermined value.

Means for Solving the Problems In order to solve the above problems, the present invention, as shown in FIG. It has a detectable range larger than the maximum swing range of the sewing needle in order to detect the position of the side edge of the work cloth extending in a direction intersecting the swing direction, and the cloth edge position with respect to the position of the side edge in the swing direction. (b) A cloth detector that generates a signal, and (b) a needle position command signal that generates a needle position command signal that changes according to the cloth edge position signal so that the swing position of the sewing needle is a predetermined distance from the side edge of the workpiece cloth. needle positioning means for controlling the operation of the swing control motor; (C) needle position range setting means for setting a signal range corresponding to the maximum swing range of the sewing needle or a narrower range;
(e) determining means for generating a permission signal when the value of the needle position command signal is within the signal range and generating an abnormal signal when the value exceeds the signal range; (e) while the permission signal is being generated;
a speed control means for controlling the speed of the sewing machine motor to a low speed when the deviation value of the value of the needle position command signal from the reference value within the signal range is large and to a high speed when the deviation value is small; Needle stopping means is provided for stopping the sewing needle by stopping the sewing machine motor when a signal is generated.

Function: In the zigzag sewing machine configured as described above and capable of copying the fabric edge, the operator can properly correct the position of the workpiece fabric and keep the sewing needle within the maximum swing range or a narrower range. If the seam is sagging, the determining means issues a permission signal, and the sewing machine motor is operated to perform sewing with a predetermined seam allowance.

During this time, the sewing machine motor is rotated at high speed when the swing position of the sewing needle is close to the reference position, and the rotational speed is decreased as the swing position of the sewing needle deviates from the reference position. When the sewing needle finally reaches the end of the maximum swing range or a narrower range, the stop means stops the sewing machine motor based on an abnormality signal from the determination means.

Effects of the Invention As mentioned above, the sewing machine motor automatically stops when the sewing needle reaches the maximum swing range or the end of a narrower range, so even if the seam allowance is not maintained at a predetermined size, the sewing machine motor automatically stops. This has the effect of eliminating the possibility that the operator will continue sewing without noticing the situation.

In addition, when the sewing needle swing position is close to the reference position, the sewing machine motor is rotated at high speed, so sewing work is performed efficiently, and as the sewing needle swing position deviates from the reference position, the sewing machine motor rotation speed automatically increases. Since the feed rate of the work cloth is also reduced, the position correction operation of the work cloth becomes easier, and the effect of making it easier to carry out cloth edge copy stitching can be obtained.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

As shown in FIG. 2, the sewing machine of this embodiment includes a bed 10 with a flat top surface, a pedestal 12 rising from the right end of the bed 10, and a cantilevered structure extending from the top of the pedestal 12. The sewing machine frame 16 includes an upper arm 14 extending substantially parallel to the bed 10. A start/stop switch 20 for controlling starting and stopping of the sewing machine motor is provided on the head 18 on the free end side of the upper arm 14.
4 is further provided with a display board 22 on which images representing a plurality of types of stitch patterns that can be formed by this sewing machine are displayed, and a pattern selection switch 24 that is operated to select a stitch pattern. The pillar portion 12 also includes a copying stitch switch 26 for performing copying stitching to form a seam line at a certain distance from the fabric edge, and a speed adjustment operation member 28. The needle swing adjustment operation member 30 and the feed amount adjustment operation member 32 are sunk.

Figure 3 shows the head 18 with the cover removed.
A needle bar stand 36 serving as a swing support frame is attached to a protrusion 34 fixed to the sewing machine frame 16 so as to be swingable in a vertical plane by a shaft 38 .

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 (not shown) via a needle bar holder 44, etc., and the sewing needle 42 is caused to reciprocate up and down by a needle up and down drive means comprised of these. Further, a needle swing control motor (not shown) is connected to the needle bar stand 36 via a Z link 46, etc., and the needle bar stand 36 is caused to swing by driving this needle swing control motor. This allows the sewing needle 42 to swing laterally. This sewing needle 42 constitutes a stitch forming mechanism together with a hook (not shown) provided on the bed 10 side.

A cloth detector 54 is fixed to the lower surface of the sewing machine head 18 via a bracket 52. The cloth detector 54 includes a light-emitting element 56 that emits infrared rays as a light-emitting part, and a light-receiving element 58 that receives reflected infrared rays as a light-receiving part. It includes a holder 59 for holding and a signal processing circuit (not shown). Further, an optical filter 60 is provided near the light receiving element 58, which allows infrared rays to pass through but blocks light of other wavelengths.

As is clear from FIG. 2, an opening is formed in the upper surface of the bed 10, and this opening is closed by a needle plate 66. A plurality of slots are formed in the throat plate 66, from which the feed dog 68 can protrude upward. This feed dog 68 is connected to a feed control motor as a feed control actuator, and constitutes a feed device that is synchronized with the up and down reciprocating movement of the sewing needle and provides a feed movement with a variable feed amount, and is not shown in the drawings. This feeds the work cloth 70 in the front and back direction in cooperation with the presser foot.

A needle hole 72 which is further elongated in the left-right direction is formed in the throat plate 66, and a reflective surface 74 is formed close to and parallel to this needle hole 72. This reflective surface 74 reflects infrared rays emitted from the light emitting element 56 of the cloth detector 54 toward the light receiving element 58, and as shown in FIG. The light-emitting element 56 and the light-receiving element 58 are arranged a short distance in front of each other in the horizontal direction in a plane parallel to the swinging plane of the needle bar stand 36. However, it is an arcuate concave surface centered on the midpoint P of the separation distance. Therefore, a straight line connecting this midpoint P and any one point Q on the reflective surface 74 At the same time, the angle θ formed by the straight line connecting the light emitting element 56 and the point Q and the straight line connecting the light receiving element 58 and the point Q is bisected. The light is accurately reflected toward the light-receiving element 58.As a result, although the light-receiving element 58 itself has an extremely narrow linearity range and is inexpensive, it is processed as shown in FIG. A linear relationship is established over a wide range between the edge position of the cloth 70 and the output voltage of the cloth detector 54, and the cloth detector 54 has a detectable range wider than the maximum swing range of the sewing needle 42. Note that the reflective surface 74
is provided very close to the needle hole 72, whereas
The fabric detector 54 is located a certain distance forward (toward the operator) from the needle bar 40 to avoid interference with the needle bar stand 36 and the guides that guide the swinging of the needle bar stand 36. The reflecting surface 74 is formed to be slightly inclined toward the operator, and is configured to accurately reflect the light emitted from the light emitting element 56 toward the light receiving element 58.

Figure 5 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 FIG. A pattern selection counter 80 is connected to this pattern selection switch 24 and counts the number of times the pattern selection switch 24 is operated.
The count contents are supplied to the stitch data generator 82.

Further, although not shown, a plurality of light emitting diodes disposed on the display board 22 are caused to emit light in accordance with the count contents, so that the selected stitch pattern is displayed.

The stitch data generator 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. , which is supplied as a stitch control signal to a feed calculation device 84 and a needle swing calculation device 86.

That is, the stitch data generator 82 is connected to a timing pulse generator 88 that generates one pulse signal every time the needle bar 40 makes one reciprocation up and down movement, and each time this timing pulse is supplied, Stitch data generator 82
supplies the feed data and needle swing data in the stitch data to the feed calculation device 84 and needle swing calculation device 86, respectively.

A feed amount adjusting device 89 is connected to the feed calculating device 84, and a needle swing calculating device 90 is connected to the needle swing calculating device 86. The feed amount adjustment device 89 supplies feed adjustment data that changes according to the operation of the feed amount adjustment operation member 32 to the feed calculation device 84 . The feed calculation device 84 multiplies this feed adjustment data by the feed data supplied from the stitch data generation device 82, and applies the feed amount adjustment operation member 32ψ to the feed data supplied from the stitch data generation device 82. After making changes corresponding to the operating position, it is supplied to the feed drive control circuit 92. Similarly, the needle swing calculation device 86 changes the needle swing data supplied from the stitch data generator 82 in accordance with the position of the needle swing adjustment operation member 30, and then changes the needle swing data via the multiplexer 94. It is supplied to the control circuit 96. As a result, the feed drive control circuit 92 controls the feed control motor 98, and the needle swing control circuit 96 controls the needle swing control motor 100, so that the swing of the sewing needle 42 and the amount of cloth feed by the feed dog 68 are controlled appropriately. controlled,
The stitch pattern selected by operating the pattern selection switch 24 will be formed.

The speed adjustment operation member 28 is for changing the speed adjustment data of the speed joint device 102 shown in the lower right portion of FIG. 5. The speed adjustment device 102 is connected to a sewing machine motor control device 104, and the sewing machine motor control device 104 determines the rotational speed of the sewing machine motor based on the speed adjustment data supplied from the speed adjustment device 102, and controls the sewing machine motor drive circuit 106. Sewing machine motor 1 through
08 is rotated at a speed corresponding to the position of the speed adjustment operation member 28.

Further, the copy sewing switch 26 is connected to the pattern selection counter 80.
．． Multiplexer 94 and sewing machine motor control device 10
4, the pattern selection counter 80 is reset in response to the rise of the signal ET from the copy stitch switch 26, and the stitch data generator 82 outputs straight stitch data, and the stitch data generator 82 outputs straight stitch data. Reference numeral 94 is switched to a state in which needle position data Dρ, which is a needle position command signal from the tracing line control device 110, rather than the output signal of the needle swing calculation device 86, is supplied to the needle swing control circuit 96, and the sewing machine motor control The device 104 is the speed adjusting device 1
Instead of speed control based on speed adjustment data from 02,
A state is reached in which speed control is performed for copy stitching, which will be described later.

The fabric detector 54 is connected to the tracing line control device 110. The detection voltage Vd as a cloth edge position signal from the cloth detector 54 is supplied to the adder 112 of the tracing line control device 110. The adder 112 is supplied with a constant voltage Vc together with the detection voltage Vd, and the adder 112 changes the detection voltage V from the constant voltage Vc.
A voltage equal to the value obtained by subtracting d is output to the A/D converter 114, which digitizes it and supplies the cloth edge detection data Dd to another adder 116. This adder 116 is supplied with seam allowance data D- from a seam allowance data memory 118, and the adder 116 receives the timing pulse TP from the timing pulse generator 88 via an OR circuit 122. Each time the needle position data Dp is obtained by subtracting the seam allowance data Dw from the cloth edge detection data Dd, it is supplied as a needle position command signal to the needle swing control circuit 96 via the multiplexer 94, and the needle swing control circuit 96 The needle swing control motor 100 is controlled according to this needle position data Dp. Adder 11
2. A/D converter 114° seam allowance data memory 118. Adder 116. Multiplexer 94. Needle swing control circuit 96
etc. constitute the needle positioning means.

FIG. 6 is a diagram showing the relationship between the above voltages and data. As is clear from FIG. 6, the constant voltage Vc is
The voltage corresponding to the distance from the left end of the maximum amplitude range to the right end of the detection range of the cloth detector 54 (when the reflective surface 74 is
is the output voltage of the cloth detector 54 in a state where the left end position of the maximum amplitude range is covered by ), and the detection voltage Vd
is a voltage corresponding to the distance from the right end of the detection range to the edge of the work cloth 70. Therefore, the adder 112
The A/D converter 114 calculates the voltage corresponding to the distance from the left end position of the maximum amplitude range to the cloth edge of the work cloth 70, and the A/D converter 114 digitizes this to calculate the distance from the left end position of the maximum amplitude range to the cloth edge. Cloth edge detection data Dd, which is a digital value corresponding to , is supplied to the adder 116 . Then, the adder 116 calculates the seam allowance data D from this cloth edge detection data Dd.
By subtracting w, needle position data Dp corresponding to the distance from the left end position of the maximum amplitude range to the stitch line is obtained, and this is supplied to the multiplexer 94.

The seam allowance data Dw is output from the seam allowance data memory 118 based on the output signal of the needle swing joint device 90. That is, a plurality of pieces of seam allowance data are stored in the seam allowance data memory 118 in correspondence with the needle swing adjustment data that is the output signal of the needle swing joint device 90, and any of these data corresponds to the needle swing adjustment data. It is selected in accordance with the needle swing adjustment data from the adjustment device 90 and is supplied to the adder 116.

Adder 116 is connected to timing pulse generator 8 as described above.
However, when the sewing machine motor 108 is stopped, this timing pulse TP is not supplied and the adder 116 does not operate. , while the sewing machine motor 108 is stopped, the clock pulse from the clock pulse generator 126 is supplied to the adder 116 as a pseudo timing pulse.

The clock pulse is supplied to the adder 116 via the AND circuit 128 when the sewing machine motor is stopped and the sewing needle 42 is in the needle-up position.

As is clear from the above explanation, the needle swing adjustment data, which is the output signal of the needle swing adjustment device 90, is
6 is off, the needle oscillation data from the stitch data generator 82 is combined with the needle oscillation data from the stitch data generator 82 in the needle oscillation calculation device 86, and is supplied to the needle oscillation control circuit 96 via the multiplexer 94. 26 is on, the seam allowance data Dw is stored in the seam allowance data memory 118.
Further, the adder 116 converts the data into needle position data Dp, which is supplied to the needle swing control circuit 96 via the multiplexer 94. The needle swing adjustment device 90 is an adjustment device that can be switched between two operation modes, and the copying stitch switch 26 constitutes a switching means for switching the adjustment device between a first operation mode and a second operation mode. That's what I'm doing.

The needle position data Dp from the adder 116 is also supplied to a command speed data memory 130 and a discrimination circuit 132. In the command speed data memory 130,
A plurality of sewing machine motor command speed data are stored corresponding to needle position data Dp. This command speed is set to be highest when the needle position data Dp is a reference value corresponding to the center of the maximum swing range of the sewing needle 42, and to become lower as the deviation from the center value increases. .

That is, when the sewing needle 42 is located near the center of the maximum swing range, the position of the fabric edge is appropriate and there is no need to correct the position of the workpiece cloth 70, so sewing is performed at high speed, and the position of the sewing needle 42 is Since it is necessary to make a large positional correction of the workpiece cloth 70 as it approaches the end of the maximum swing range, the sewing speed is reduced, and the command speed data memory 130 constitutes a speed control means. There is.

A needle position range setter 134 as needle position range setting means is connected to the discrimination circuit 132, and as shown in FIG.
1 and C2, and data B1 and B corresponding to both ends of the sewing possible swing range, which is set slightly narrower than the maximum swing range.
2 is supplied to the discrimination circuit 132. The determination circuit 132 converts the device data Dp formed by the adder 116 into these data Bl, B2 . Comparing with CI and C2, when the hand position data Dp is in the range from data B1 to B2, a permission signal is issued, and when it is between data B2 and 02 and between C1 and B2, a limit signal is issued, and C2
If the value is larger than C1 or smaller than C1, an abnormal signal is generated. The range from data C1 to data C2 is the first signal range corresponding to the maximum swing range, data B1
The range from to data B2 is the second signal range corresponding to the sewing possible swing range, and the discrimination circuit 13
2 constitutes a discriminating means for discriminating to what signal range the needle position command signal belongs.

A permission signal is sent to gate 136 to permit commanded speed data from commanded speed data memory 130 to be provided to sewing machine motor controller 104 . On the other hand, the limit signal and the abnormal signal are supplied to the needle position detector 138 and passed through the OR circuit 140 to the start/stop command circuit 142.
Also supplied. The needle position detector 138 detects that when the limit signal is supplied, the sewing needle 42 is located at the bed 1.
0, a needle position detection signal is supplied to the sewing machine motor control device 104, and when the abnormal signal is being supplied, the sewing needle 42 has its tip positioned above the upper surface of the sewing machine bed 10. A needle position detection signal is supplied when the needle reaches the needle up position located at . Further, the start/stop command circuit 142 originally supplies a start command and a stop command for the sewing machine motor 108 to the sewing machine motor control device 104 in response to the operation of the start/stop switch 20, but if a limit signal or an abnormal signal is supplied. After receiving this stop command signal, the sewing machine motor control device 104 stops the sewing machine motor 108 when it receives a needle position detection signal from the needle position detector 138. let Start/stop command circuit 1
42 and the sewing machine motor control device 104 constitute needle stopping means.

When copy stitching is performed using the sewing machine configured as described above, the operator first sets the workpiece cloth 70 so that the desired seam line formation position is approximately at the center of the needle hole 72. Then, when the copying stitch switch 26 is operated, the pattern selection counter 80 is reset, and no matter what stitch pattern has been selected up to that point, straight stitching will be selected. Further, the multiplexer 94 is switched to a state where the needle position data Dp of the profile line control device 110 is supplied to the needle swing control circuit 96, and the sewing machine motor control device 104 is also switched to the sewing machine based on the data from the profile line control device 110. A state is entered in which the motor 108 is controlled.

In the state where the work cloth 70 is set as described above,
The cloth detector 54 supplies the adder 112 with a detection voltage Vd corresponding to the area of the detection range not covered by the work cloth 70 . The adder 112 converts this detected voltage Vd into a constant voltage V
supplying the voltage subtracted from c to the A/D converter 114;
A/D converter 114 supplies this to adder 116 as cloth edge detection data Dd. In this state, the sewing machine has not yet been started and the sewing needle 42 is in the raised position, so the clock pulse from the clock pulse generator 126 is supplied to the adder 116 via the AND circuit 128 and the OR circuit 122. Ru. The adder 116 that receives this clock pulse subtracts the seam allowance data D- from the cloth edge detection data Dd and outputs needle position data Dp.

Multiplexer 94 supplies this needle position data Dp to needle swing control circuit 96, and needle swing control circuit 96 drives needle swing control motor 100 based on this needle position data Dp. As a result, the needle bar stand 36 is swung, and the needle bar 4
The position of the sewing needle 42 supported through the needle 0 is changed. If the position of the sewing needle 42 is as desired, the operator operates the start/stop switch 20 to start the sewing machine motor 108, but if not, the operator operates the needle swing adjustment operating member 30. This operation changes the needle swing adjustment data, which is the output signal of the needle swing adjustment device 90, and based on the changed needle swing adjustment data, seam allowance data D- is output from the seam allowance data memory 118, and the seam allowance data D- is added. 116. Thereafter, the position of the sewing needle 42 is controlled based on this new seam allowance data Dw as in the above case.

When the sewing needle 42 reaches the desired position, the operator operates the start/stop switch 20 to start the sewing machine motor 108. As a result, a seam line is formed at the desired position and sewing is performed with the desired seam allowance, but the size of the seam formed at this time is determined by the feed data supplied from the stitch data generator 82. This is determined by the feed adjustment data supplied from the feed amount adjustment device 89, as in normal sewing work.

The work cloth 70 is fed as the seam line is formed, and during this process the operator maintains the position of the cloth edge approximately constant, but it is inevitable that this position will fluctuate to some extent. When the cloth edge position changes, the detection voltage Vd from the cloth detection teeth 54 changes. During operation of the sewing machine, the timing pulse TP from the timing pulse generator 88 is
is supplied to the adder 116 via the OR circuit 122, so the adder 11
6 outputs needle position data Dp, which is supplied to multiplexer 94, and thereafter the position of sewing needle 42 is changed in the same manner as when the sewing machine is stopped. When the position of the edge of the work cloth 70 changes, the position of the sewing needle 42 is automatically changed to follow it, thereby keeping the seam allowance constant.

While the fabric edge stitching is being performed in this manner, the operator needs to correct the position of the workpiece cloth 70 so that the position of the sewing needle 42 is located as close to the center of the maximum swing range as possible. This is because once the position of the sewing needle 42 reaches the end of the maximum swing range, it will no longer be able to follow fluctuations in the position of the fabric edge. However, in the sewing machine of this embodiment, since the maximum swing range is 7 mm, there is a possibility that the position of the workpiece cloth 70 cannot be continuously corrected to prevent the above situation from occurring.

Therefore, in this embodiment, when the sewing needle 42 is located near the center of the maximum swing range, the sewing machine motor 1
08 is rotated at high speed, but the rotation speed is reduced as it approaches the end of the maximum swing range. Data instructing a low speed is supplied from the command speed data memory 130 to the sewing machine motor control device 104, and the rotational speed of the sewing machine motor 108 is reduced.

The sewing speed automatically decreases as the required amount of correction in the position of the workpiece cloth 70 increases, and as the sewing speed decreases, it becomes easier to correct the workpiece cloth 70, and as a result, it becomes easier to perform fabric edge stitching. This means that you can do it.

However, if the position of the sewing needle 42 reaches the end of the maximum swing range or the vicinity thereof, the sewing machine motor 108 is automatically stopped. That is, while the needle position data Dp from the adder 116 is within the range from data B1 to data B2 from the needle swing range setter 134, the discrimination circuit 132 outputs a permission signal and opens the gate 136. The speed control of the sewing machine motor 108 as described above is performed, but when the needle position data Dp becomes larger than the data B2 or smaller than the data B1, the permission signal is no longer output from the discrimination circuit 132. Gate 1
36 is closed and the limit signal is transmitted to the needle position detector 1.
38 and the start/stop command circuit 142. The start/stop command circuit 142 supplies a sewing machine stop command signal to the sewing machine motor control device 104 in response to the limit signal. In response, the sewing machine motor control device 104 controls the sewing machine motor 108.
The rotational speed of the motor is reduced to a speed at which it can be stopped at any time. Then, when the sewing needle 42 reaches the needle down position, the needle position detector 138 outputs a needle position detection signal, and upon receiving this signal, the sewing machine motor control device 104 starts the sewing machine motor 1 at that position.
Stop 08.

In this state, the sewing needle 42 has penetrated the workpiece cloth 70, so the operator moves the workpiece cloth 70 around the sewing needle 42.
After rotating by a small angle, the start/stop switch 20 is operated to start the sewing machine motor 108. As a result, sewing is restarted, but since the position of the workpiece cloth 70 has been sufficiently corrected by the rotation operation described above, the position of the sewing needle 42 approaches the center of the maximum swing range as the workpiece cloth 70 is fed. That will happen.

On the other hand, if an abnormality signal is issued from the discrimination circuit 132, the needle position detector 138 outputs a needle position detection signal when the sewing needle 42 reaches the needle-up position, and the sewing machine motor control device 104 receives the signal. stops the sewing machine motor 108. The abnormality signal is issued when the sewing needle 42 reaches the end of its maximum swing range and the seam allowance is no longer kept constant, so it is necessary to redo copy stitching at least in the vicinity. Since the sewing needle 42 is stopped at the counting position, the operator can freely move the workpiece cloth 70 and redo copy stitching.

In the embodiment described in detail above, when the sewing needle 42 exceeds the sewing possible swing range which is narrower than the maximum swing range, the sewing machine motor is stopped at the needle down position, and the sewing machine motor is stopped at the needle down position. However, this is not essential, and the sewing machine motor should be able to be stopped at an arbitrary position of the sewing needle 42 when the swing range that allows sewing is exceeded. Alternatively, as shown in FIG. 8, it is also possible to stop the sewing machine motor only when the sewing needle reaches the end of its maximum swing range.

In the embodiment of FIG. 8, the needle position range setter 134a
data C1 and C2 corresponding to both ends of the maximum swing range
In addition, the discrimination circuit 13
2a is a device composed of an adder 116. While data Dp is greater than or equal to data 01 and less than C2, a permission signal is supplied to the sewing machine motor control device 104a, and needle position data Dp becomes smaller than data C1 or larger than data C2. When this occurs, an abnormality signal is supplied to the start/stop command circuit 142a. Sewing machine motor control device 104
a controls the sewing machine motor 10B based on the command speed data from the open command speed data memory 130 to which the permission signal is supplied, and the start/stop command circuit 142a issues the stop command signal in response to the abnormality signal from the discrimination circuit 132a. When this is output, the sewing machine motor 108 is stopped.

Since the other parts are the same as those in the previous embodiment, detailed explanation will be omitted.

Further, in the above embodiment, the needle position data Dp from the adder 116 was directly supplied to the command speed data memo I7130, but as shown in FIG. deviation calculator 150 together with reference data (data corresponding to the center of the maximum swing range)
It is also possible that the deviation calculator 150 calculates the deviation of the needle position data Dp from the reference data, and the calculated deviation data is supplied to the command speed data memory 130b. In this way, the storage capacity of the command speed data memo IJ 130b can be reduced by half.

In each of the above embodiments, the reference position of the sewing needle was set at the center of the maximum swing range, but this is not essential, and the reference position may also be set a certain distance to the right or left from the center. It is possible, and it is not necessarily essential to reduce the speed of the sewing machine motor in multiple steps depending on the distance from the reference position of the sewing needle.The effect of the present invention can be obtained by changing the speed to at least two steps, high and low. It is also possible to reduce the rotational speed of the sewing machine motor steplessly as the deviation data of the needle position data with respect to the reference data increases. In this case, it is not essential that the relationship between the deviation data and the sewing machine motor rotation speed be linear.

In the above embodiment, a reflection type photosensor is used as the fabric detector, which has the advantage that the edge position of the fabric can be detected over a wide range using an inexpensive photosensor. It is also possible to employ a transmission type photosensor that is disposed in the work cloth and outputs a signal corresponding to the area of the portion not covered by the work cloth.

In the embodiment described above, even when the sewing machine motor is stopped, the position of the sewing needle 42 can be changed according to the operation of the needle swing adjustment operation member 30, so that the stitch line is set at the desired position from the beginning of sewing. However, if this is not necessary, the clock pulse generator 126 and the AND circuit 128 can be omitted.

Furthermore, in the above embodiment, straight stitching is automatically selected when copying stitching is performed, but this is because straight stitching is generally used for copying stitching, and it is not possible to select It is also possible to perform copy stitching using the following stitch patterns.

In addition, the configuration of the copying stitch control device 110 may be changed, the needle bar stand 36 may be oscillated about a substantially vertical axis to change the lateral position of the sewing needle, or the overall configuration of the zigzag sewing machine may be changed. , various modifications based on the knowledge of those skilled in the art.

The invention can be practiced in modified forms.

[Brief explanation of drawings]

FIG. 1 is a diagram conceptually showing the configuration of the present invention. FIG. 2 is a perspective view schematically showing the appearance of a zigzag sewing machine according to an embodiment of the present invention. FIG. 3 is a front view of the head of the sewing machine with its cover removed. FIG. 4 is an explanatory diagram showing the relative positional relationship between the fabric detector and the reflective surface in the same sewing machine and the range in which linearity can be obtained from the fabric detector. FIG. 5 is a block diagram showing the control circuit of the sewing machine. FIG. 6 is an explanatory diagram showing needle position control in the same sewing machine. FIG. 7 is an explanatory diagram showing the relationship between the maximum swing range of the sewing needle and the range in which permissible, limit, and abnormal signals are output from the discrimination circuit. FIGS. 8 and 9 are block diagrams showing part of the control circuit in different embodiments of the present invention. 42: Sewing needle (stitch forming mechanism) 54: Cloth detector 70: Work cloth 74: Reflective surface 100: Needle swing control motor 108: Sewing machine motor 130.130a: Command speed data memory (speed control means) 132.132a: Discrimination circuit (discrimination means) 134.13
4a: Needle position range setting device (needle position range setting means)

Claims (1)

[Claims] Includes a sewing needle capable of vertical reciprocating movement and lateral rocking movement,
A zigzag sewing machine that includes a stitch forming mechanism driven by a sewing machine motor and a needle swing control motor that controls the swing position of the sewing needle, and that changes the stitch forming position by operating the needle swing control motor, The needle has a detectable range larger than the maximum swing range of the sewing needle in order to detect the position of a side edge of the work cloth extending in a direction intersecting the swing direction of the sewing needle, and has a detectable range that is larger than the maximum swing range of the sewing needle, and is related to the position of the side edge in the swing direction. a cloth detector that generates a cloth edge position signal; and a needle position command signal that changes according to the cloth edge position signal so that the swinging position of the sewing needle is a predetermined distance away from the side edge of the work cloth. needle positioning means for controlling the operation of the needle swing control motor; needle position range setting means for setting a signal range corresponding to the maximum swing range of the sewing needle or a narrower range; determining means for generating a permission signal when the value of the position command signal is within the signal range and generating an abnormal signal when the value exceeds the signal range; speed control means for controlling the speed of the sewing machine motor to a low speed when the deviation value of the value of the needle position command signal from a reference value is large and to a high speed when the deviation value is small; and the abnormal signal is generated. 1. A fabric edge copying sewing machine, comprising: a needle stopping means for stopping the sewing needle by stopping the sewing machine motor.