JPH0142707B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a zigzag sewing machine,
In particular, the present invention relates to a cloth edge tracing sewing machine that forms a seam line at a predetermined distance from a side edge (referred to as a cloth edge) of a workpiece cloth.

BACKGROUND ART A 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 rocking movement of the sewing needle. This zigzag sewing machine capable of sewing fabric edges is already known from the specification of US Pat. No. 4,248,168. The position of the edge of the fabric is detected by a fabric detector consisting of a transmission type photo sensor, 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 will be done.

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

Problems to be Solved by the Invention However, in conventional fabric edge copying sewing machines of this type, the distance between the fabric edge and the seam line, that is, the seam allowance, is not maintained at a predetermined value. There is a possibility that you will continue sewing without noticing, and even if you notice, the sewing speed, that is, the feed speed of the work cloth is high, so it will not be necessary to correct the position of the work cloth, and therefore the seam allowance may not reach the desired value. There was a problem in which a situation occurred in which the device became deviated from the original.

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, 7 mm, 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 the predetermined value will not be maintained.
In addition, if the operator notices that such a situation is likely to occur, he or she may
In other words, it is necessary to return the position of the sewing needle toward the center of its maximum swing range by rotating the work cloth by a small angle around the intersection of the center line of the sewing needle and the top surface of the throat plate, but the feed rate If this is large, the position of the work cloth cannot be corrected in time, and the sewing needle reaches the end of its maximum swing range, making it impossible to control the needle position and causing the seam allowance to deviate from a predetermined value.

Means for Solving the Problems In order to solve the above problems, the present invention provides a zigzag sewing machine equipped with the stitch forming mechanism and needle swing control motor, as shown in FIG. 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 of the fabric edge with respect to the position of the side edge in the swing direction. (b) A cloth detector that generates a position signal, and (b) 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 from the side edge of the workpiece cloth. (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; d) 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; (f) 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 an abnormal signal is generated.

In the zigzag sewing machine configured as described above that is capable of copying the fabric edge, the position of the workpiece fabric is properly corrected by the operator, and the sewing needle is moved within the maximum swing range or within a narrower range. If it is maintained, a permission signal is issued from the determining means, 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 end of the maximum swing range or a narrower range, so even if the seam allowance is not maintained at a predetermined size, 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 the embodiment includes a bed 10 with a flat top surface, a leg 12 rising from the right end of the bed 10, and a cantilevered section extending from the upper end of the leg 12. The sewing machine frame 16 includes an upper arm 14 extending substantially parallel to the bed 10. Head 1 on the free end side of the upper arm 14
8 is provided with a start/stop switch 20 for controlling the start and stop of the sewing machine motor, and the upper arm 14 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 is provided which is operated to select a stitch pattern. In addition, the pillar part 1
2 includes a copy sewing switch 26 for performing copy sewing that forms a seam line at a certain distance from the edge of the fabric.
A speed adjustment operation member 28, a needle swing adjustment operation member 30, and a feed amount adjustment operation member 32 are provided.

FIG. 3 shows a state in which the cover of the head 18 is removed, and a projection 34 fixed to the sewing machine frame 16 has a
A needle bar stand 36 serving as a swing support frame is mounted by a shaft 38 so as to be swingable in a vertical plane. 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 attached to the lower end of the needle bar 40.
is fixed. The needle bar 40 is connected to a sewing machine motor (not shown) via a needle bar holder 44 and the like, and the sewing needle 4 is moved by a needle up and down driving means consisting of the needle bar holder 44 and the like.
2 can be moved up and down. Further, a needle swing control motor (not shown) is connected to the needle bar stand 36 via a Z link rod 46, etc., and the needle bar stand 36 swings as the needle swing control motor drives. By being moved, the sewing needle 42 is made 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. Cloth detector 5
Reference numeral 4 includes a light emitting element 56 that emits infrared rays as a light emitting part, a light receiving element 58 that receives reflected infrared rays as a light receiving part, and a holder that holds the light emitting element 56 and the light receiving element 58. 59 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 connected to the throat plate 6.
It is blocked by 6. A plurality of slots are formed in this throat plate 66, from which a 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; illustration is omitted. 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. 4a, the light emitting element 56 and the light receiving element 58 It is an arcuate concave surface centered on the central point P. The light-emitting element 56 and the light-receiving element 58 are arranged horizontally apart from each other by a small distance in a plane parallel to the swinging plane of the needle bar stand 36, and are arranged in a circular arc centered at the midpoint P of the separation distance. It is considered to be a concave surface. Therefore, a straight line connecting this midpoint P and any one point Q on the reflective surface 74 is perpendicular to the reflective surface 74, and a straight line connecting the light emitting element 56 and the point Q and a straight line connecting the light receiving element 58 and the point Q are perpendicular to the reflective surface 74. The angle θ formed by the straight line connecting the two is divided into two equal parts, and the light emitted from the light emitting element 56 toward the point Q is accurately reflected toward the light receiving element 58. As a result, although the light-receiving element 58 itself has an extremely narrow range of linearity and is inexpensive, as shown in FIG. A linear relationship is established over a wide range between the two, and the cloth detector 54 has a detectable range that is wider than the maximum swing range of the sewing needle 42. Note that while the reflective surface 74 is provided very close to the needle hole 72, the fabric detector 54 does not interfere with the needle bar stand 36 and the guide that guides the swinging of the needle bar stand 36. Since the reflective surface 74 is provided at a position a certain distance forward (operator side) from the needle bar 40 to avoid
The light emitted from the light receiving element 6 is accurately reflected 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 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 provided 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 generator 82 stores stitch data corresponding to each of the stitch patterns that can be formed.
A pattern selection counter 80 from among those stitch data
Select the stitch data corresponding to the count contents,
This 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 generating device 82 supplies feed data and needle swing data in the stitch data to feed calculation device 84 and needle swing calculation device 86, respectively.

The feed calculation device 84 includes a feed amount adjustment device 89.
However, a needle swing adjustment device 90 is also connected to each needle swing calculation device 86. The feed amount adjustment device 89 sends feed adjustment data that changes according to the operation of the feed amount adjustment operation member 32 to the calculation device 8.
Supply to 4. 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 32 to the feed data supplied from the stitch data generation device 82. After making changes corresponding to the operating position, the data 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
The signal is supplied to a needle swing control circuit 96 via a multiplexer 94. As a result, the feed drive control circuit 92 controls the feed control motor 98 and the needle swing control circuit 96.
control the needle swing control motors 100, the swing of the sewing needle 42 and the amount of cloth feed by the feed dog 68 are appropriately controlled, and the stitch pattern selected by the operation of the pattern selection switch 24 is formed. It happens.

The speed adjustment operation member 28 is for changing the speed adjustment data of the speed adjustment device 102 shown in the lower right portion of FIG. 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 stitch switch 26 is connected to a pattern selection counter 80, a multiplexer 94, and a sewing machine motor control device 104, and in response to the rise of the signal ET from the copy stitch switch 26, the pattern selection counter 80 is reset and the sewing is started. Stitch data for straight stitching is output from the stitch data generator 82, and needle position data, which is a needle position command signal, is output from the copying stitch control device 110 instead of the output signal of the needle swing calculation device 86, which is the multiplexer 94.
Dp is switched to the state where Dp is supplied to the needle swing control circuit 96, and the sewing machine motor control device 104 does not perform speed control based on speed adjustment data from the speed adjustment device 102, but speed control for copy stitching described later. It will be in the state to perform.

The copy sewing control device 110 includes the cloth detector 54.
is connected. The detection voltage Vd as a cloth edge position signal from the cloth detector 54 is supplied to the adder 112 of the copy sewing control device 110. The adder 112 is supplied with a constant voltage Vc along with the detection voltage Vd, and the adder 112 directs a voltage equal to the magnitude obtained by subtracting the detection voltage Vd from the constant voltage Vc to the A/D converter 114. Once output, the A/D converter 114 digitizes it and sends the cloth edge detection data Dd to another adder 116.
supply to. This adder 116 is supplied with seam allowance data Dw from a seam allowance data memory 118, and the adder 116 receives a timing pulse TP from the timing pulse generator 88.
is supplied via the OR circuit 122, the needle position data Dp obtained by subtracting the seam allowance data Dw from the fabric edge detection data Dd is supplied as a needle position command signal to the needle swing control circuit 96 via the multiplexer 94, and the needle The swing control circuit 96 is configured to control the needle swing control motor 100 in accordance with this needle position data Dp. The adder 112, A/D converter 114, seam allowance data memory 118, adder 116, multiplexer 94, needle swing control circuit 96, etc. constitute needle positioning means.

FIG. 6 is a diagram showing the relationship between the above voltages and data. As is clear from Figure 6, constant voltage
Vc is a voltage corresponding to the distance from the left end of the maximum amplitude range of the sewing needle 42 to the right end of the detection range of the cloth detector 54 (when the reflective surface 74 is covered by the work cloth 70 to the left end of the maximum amplitude range) (output voltage of the cloth detector 54), 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 workpiece cloth 70. Therefore, the adder 112 calculates the value of the workpiece cloth 7 from the left end position of the maximum amplitude range of the sewing needle 42.
Calculate the voltage corresponding to the distance to the cloth edge of 0,
The A/D converter 114 digitizes this and supplies cloth edge detection data Dd, which is a digital value corresponding to the distance from the left end position of the maximum amplitude range to the cloth edge, to the adder 116. And adder 1
16 is seam allowance data Dw from this cloth edge detection data Dd
Find the needle position data Dp corresponding to the distance from the left end position of the maximum amplitude range to the stitch line by subtracting
This is supplied to multiplexer 94.

The seam allowance data Dw is determined by the needle swing adjustment device 9.
Based on the output signal of 0, the seam allowance data memory 118
is output from. In other words, seam allowance data memory 1
18 stores a plurality of pieces of seam allowance data corresponding to the needle swing adjustment data that is the output signal of the needle swing adjustment device 90. It is selected according to the swing adjustment data and supplied to the adder 116.

As described above, the adder 116 performs addition every time the timing pulse TP from the timing pulse generator 88 is supplied, but when the sewing machine motor 108 is stopped, this timing pulse TP is not supplied. First, since the adder 116 stops working, the sewing machine motor 108
When the clock pulse generator 126 is stopped, the clock pulse generator 126
The clock pulses from the adder 116 are supplied as pseudo timing pulses to the adder 116. The sewing machine motor 108 is stopped, and
AND circuit 12 when sewing needle 42 is in the needle-up position
8, the clock pulse is supplied to the adder 116.

As is clear from the above description, the needle swing adjustment data, which is the output signal of the needle swing adjustment device 90, is transmitted from the stitch data generator 82 in the needle swing calculation device 86 when the copying stitch switch 26 is off. is multiplied with the needle swing data Dw and supplied to the needle swing control circuit 96 via the multiplexer 94. When the copy stitch switch 26 is on, the seam allowance data Dw is stored in the seam allowance data memory 118.
The data is further converted into needle position data Dp by an adder 116 and supplied to a needle swing control circuit 96 via a multiplexer 94. The needle swing adjustment device 90 is an adjustment device capable of switching 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
The command speed data memory 130 and discrimination circuit 132 are also supplied with the signal. The command speed data memory 130 stores a plurality of sewing machine motor command speed data corresponding to the 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. ing. 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. That's what I'm doing.

A needle position range setter 134 as a needle position range setting means is connected to the discrimination circuit 132.
As shown in FIG. 7, data C1 and C2 correspond to both ends of the maximum swing range of the sewing needle 42, and data B1 and B2 correspond to both ends of the sewing possible swing range, which is set slightly narrower than the maximum swing range. The signal is supplied to the discrimination circuit 132. The discrimination circuit 132 converts the needle position data Dp supplied from the adder 116 into data B1, B2, C1, C.
2, when the needle 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 C2, and between C1 and B2, a limit signal is issued, and when it is greater than C2. An abnormal signal is generated when the value is smaller than C1. 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.
The discrimination circuit 132 constitutes a discrimination means that discriminates 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 abnormality signal is supplied to the needle position detector 138 and also to the OR circuit 14.
It is also supplied to the start/stop command circuit 142 via 0. The needle position detector 138 detects that when the limit signal is supplied, the sewing needle 42 is located at the tip of the bed 1.
0, a needle position detection signal is supplied to the sewing machine motor control device 104, and when an abnormal signal is supplied, the sewing needle 42
is adapted to supply a needle position detection signal when its tip reaches a needle-up position located above the top surface of the sewing machine bed 10. Further, the start/stop command circuit 142 is originally intended to supply 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 a limit signal or an otherworld signal is supplied. After receiving this stop command signal, the sewing machine motor controller 104 starts the sewing machine motor 10 when it receives a needle position detection signal from the needle position detector 138.
Stop 8. The start/stop command circuit 142 and the sewing machine motor control device 104 constitute needle stopping means.

When performing copy stitching 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, copy stitch switch 26
When the button 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. In addition, the multiplexer 94 controls the copy stitching control device 110
The sewing machine motor control device 104 also enters a state of controlling the sewing machine motor 108 based on the data from the copying stitch control device 110.

In the state where the work cloth 70 is set as described above, the cloth detector 54 detects a detection voltage corresponding to the area of the portion of the detection range that is not covered by the work cloth 70.
Vd is supplied to adder 112. The adder 112 subtracts this detection voltage Vd from the constant voltage Vc and supplies it to the A/D converter 114, and the A/D converter 114 supplies this to the 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. The adder 116 receiving this clock pulse subtracts the seam allowance data Dw from the cloth edge detection data Dd and outputs needle position data Dp.

The multiplexer 94 supplies this needle position data Dp to the needle swing control circuit 96.
6 drives the needle swing control motor 100 based on this needle position data Dp. As a result, the needle bar stand 36 is swung, and the position of the sewing needle 42 supported thereon via the needle bar 40 is changed. This sewing needle 4
If the position 2 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 the seam allowance data is stored in the seam allowance data memory 118 based on the changed needle swing adjustment data.
Dw is output and supplied to adder 116. Below, as in the case above, this new seam allowance data
Position control of the sewing needle 42 is performed based on Dw.

When the sewing needle 42 is at the desired position, the operator turns the start/stop switch 20.
to start the sewing machine motor 108. As a result, a seam line is formed at a desired position and sewing is performed with a desired seam allowance, but the size of the seam formed at this time is determined by the stitch data generator 82.
Feed data and feed amount adjustment device 89 supplied from
This is determined by the feed adjustment data supplied from the sewing machine in the same way 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 this cannot be avoided to some extent. When the cloth edge position changes, the detection voltage Vd from the cloth detector 54 changes. During operation of the sewing machine, the timing pulse TP from the timing pulse generator 88 is supplied to the adder 116 via the OR circuit 122, so the adder 116 outputs needle position data Dp in response to the input of this timing pulse TP. This is then supplied to the multiplexer 94, and thereafter the position of the 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 example, the maximum swing range is 7 mm.
Therefore, it may become impossible to continue correcting the position of the work cloth 70 to prevent the above situation from occurring.

Therefore, in this embodiment, the sewing machine motor 108 is rotated at high speed when the sewing needle 42 is located near the center of the maximum swing range.
The rotation speed is reduced as the end of the maximum swing range is approached. 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 or near the end of the maximum swing range, 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 the needle position data Dp is the data B2.
or when it becomes smaller than data B1, the gate 136 where the permission signal is no longer output from the discrimination circuit 132 is closed, and the limit signal is sent to the needle position detector 138 and the start/stop command circuit 142. Supplied. 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 reduces the rotational speed of the sewing machine motor 108 to a speed at which it can be stopped indefinitely. Then, when the sewing needle 42 comes to the needle down position, the needle position detector 138 outputs a needle position detection signal, and the sewing machine motor control device 104 receiving this signal stops the sewing machine motor 108 at that position.

In this state, the sewing needle 42 has penetrated the work cloth 70, so the operator rotates the work cloth 70 by a small angle around the sewing needle 42, and then operates the start/stop switch 20 to start the sewing machine motor 108. do. 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 is changed to the maximum oscillation as the workpiece cloth 70 is fed. This will bring it closer to the center of the range of motion.

On the other hand, when 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 upper position.
Upon receiving this, sewing machine motor control device 104 stops sewing machine motor 108. The abnormal 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 the copy stitching at least in the vicinity. Since the sewing needle 42 is stopped at the needle-up 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 range narrower than the maximum swing range, the sewing machine motor is stopped at the needle down position, and when the sewing needle 42 reaches the end of the maximum swing range, the sewing machine motor is stopped. Although the sewing machine motor can be stopped at the upper position, this is not essential, and the sewing machine motor can be stopped at an arbitrary position of the sewing needle 42 when the swing range that allows sewing is exceeded, or It is also possible to stop the sewing machine motor only when the sewing needle reaches the end of its maximum swing range, as shown in FIG.

In the embodiment shown in FIG. 8, the needle position range setter 134a outputs only data C1 and C2 corresponding to both ends of the maximum swing range, and the discrimination circuit 132a outputs data C1 and C2 corresponding to both ends of the maximum swing range. A permission signal is supplied to the sewing machine motor control device 104a while the needle position data Dp is greater than or equal to data C1 and less than C2, and an abnormality signal is generated when the needle position data Dp becomes smaller than data C1 or larger than data C2. Start/stop command circuit 1
42a. The sewing machine motor control device 104a controls the sewing machine motor 108 based on the command speed data from the command speed data memory 130 while the permission signal is supplied,
The sewing machine motor 108 is stopped when the start/stop command circuit 142a outputs a stop command signal in response to an abnormality signal from the discrimination circuit 132a. Since the other parts are the same as those in the previous embodiment, detailed explanation will be omitted.

Further, in the embodiment described above, the needle position data Dp from the adder 116 was directly supplied to the command speed data memory 130, but the
As shown in the figure, the reference data (data corresponding to the center of the maximum swing range) supplied from the reference value setter 152 is supplied to the deviation calculator 150, and the deviation calculator 150 uses the reference data of the needle position data Dp. It is also possible to calculate the deviation from the command speed data and supply the calculated deviation data to the command speed data memory 130b. In this way, the storage capacity of the command speed data memory 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 to a position 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 photo sensor 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 photo sensor. It is also possible to employ a transmission type photo sensor that 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 in accordance with 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 12
6 and the AND circuit 128 can be omitted.

Furthermore, in the embodiment described above, straight stitching is automatically selected when copying stitching is performed, but this is because straight stitching is generally used for copying stitching, and is optional. 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 lateral position of the sewing needle may be changed by swinging the needle bar base 36 around a substantially vertical axis, or the overall configuration of the zigzag sewing machine may be changed. The present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

[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 in 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, {94: Multiplexer, 96: Needle swing control circuit, 112: Adder, 114: A/D converter, 116: Adder, 1
18: Seam allowance data memory} (needle positioning means), 1
00: Needle swing control motor, {104: Sewing machine motor control device, 142, 142a: Start and stop command circuit} (needle stop means), 108: Sewing machine motor, 13
0, 130a: command speed data memory (speed control means), 132, 132a: discrimination circuit (discrimination means), 134, 134a: needle position range setter (needle position range setting means).

Claims (1)

[Scope of Claims] 1. A stitch forming mechanism that includes a sewing needle capable of vertical reciprocating motion and horizontal rocking motion and is driven by a sewing machine motor, and a needle rocking control motor that controls the rocking position of the sewing needle. In a zigzag sewing machine that is equipped with a needle swing control motor and changes the stitch forming position by operating the needle swing control motor, the maximum swing of the sewing needle is adjusted to detect the position of the side edge of the workpiece cloth that extends in the direction intersecting the swing direction of the sewing needle. a cloth detector having a detectable range larger than a movement range and generating a cloth edge position signal regarding the position of the side edge in the swing direction; needle positioning means for controlling the operation of the needle swing control motor by generating a needle position command signal that changes according to the cloth edge position signal so that the sewing needle is located at a maximum swing range of the sewing needle; needle position range setting means for setting a signal range corresponding to a narrower defined range; generating a permission signal when the value of the needle position command signal is within the signal range; and generating a permission signal when the value of the needle position command signal is within the signal range; determining means for generating an abnormal signal; while the permission signal is being generated, the speed is reduced to a low speed when the deviation value of the value of the needle position command signal from a reference value within the signal range is large, and the deviation value is small; A speed control means for controlling the speed of the sewing machine motor to a high speed when the abnormal signal is generated; and a needle stop means for stopping the sewing needle by stopping the sewing machine motor when the abnormal signal is generated. Fabric edge copy sewing machine.