JPH057680A - Needle bar controlling device for sewing machine - Google Patents

Abstract

(57) [Summary] [Purpose] The object is to be able to sew a cloth having a large cloth thickness when driving a needle bar using a rack and pinion mechanism. [Structure] When the cloth thickness is large and the load resistance when the needle is stuck is large, the speed of the needle is increased in a section where the load resistance when the needle is stuck is large, and the penetrating force of the needle is increased by inertial force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle bar controller for a sewing machine, and more particularly to a device for controlling needle bar speed.

[0002]

2. Description of the Related Art Generally, a needle bar of a sewing machine holds a sewing needle at a lower end thereof, and is reciprocated in a vertical direction by a set number of cycles by a needle bar drive motor. When the needle bar descends, the tip of the needle through which the needle thread is inserted penetrates the work cloth to be sewn. Then, as the needle bar rises, a thread loop of the upper thread is formed,
After the thread hook is captured by the outer hook provided below the feed dog, the outer hook rotates once to entangle the upper thread and the lower thread to form a stitch.

[0003]

However, in the above sewing machine, the torque of the needle bar drive motor is small when the thickness of the work cloth is very large or when the weave is very finely clogged. There was a case where it was difficult or impossible for the needle to penetrate. Therefore, in order to sew such a work cloth, the needle bar drive motor must be made large in size, which causes a problem of high cost. In view of this problem, the present invention provides a device for controlling the needle bar speed so that the work cloth, which has been difficult to sew in the past, can be sewn well without making the needle bar drive motor large. This was done as an issue.

[0004]

In order to solve this problem, a needle bar control device for a sewing machine according to the present invention, as shown in FIG. 1, is an increase detecting whether or not it is necessary to increase the needle bar descending speed. When the necessity detection means and the detection result of the increase necessity detection means are necessary, the needle bar drive motor at least when the tip of the sewing needle penetrates the work cloth without changing the set cycle number. And needle bar speed control means for increasing the operating speed of the. The increase necessity detecting means may determine whether or not there is a need for speed increase based on whether or not the reference thickness exceeds the reference thickness, for example, based on a constant thickness of the work cloth. It is also possible to determine whether or not there is a need without considering the two conditions, based on the degree of difficulty of penetration of the sewing needle when performing one cycle of sewing. In addition, the operator sees the condition of the work cloth and decides whether or not there is a need to increase the speed, and when there is a need, an electric signal is generated by operating a switch etc. It may be used as the necessity detecting means.

[0005]

In the needle bar control device configured as described above, when the thickness of the work cloth or the degree of fineness of the texture is general, the detection result of the increase necessity detecting means is Since it is not necessary to increase the needle bar lowering speed, the needle bar speed control means does not increase the speed of the needle bar drive motor. On the other hand, when the work cloths are thick or piled up, or the weave is very clogged, the detection result becomes necessary. Therefore, the needle bar speed control means of the needle bar drive motor is used. The actuation speed is increased and the needle bar lowering speed is increased. The descending speed of the needle bar may be at least when the tip of the sewing needle penetrates the work cloth, that is, when the sewing needle penetrates the work cloth, and even if the needle bar is accelerated from the beginning of descent, there is a needle bar. The speed may be increased from the time when the fixed height is reached. Also, after the sewing needle penetrates the work cloth,
It is desirable, but not essential, to reduce the descending speed to reduce vibration and noise on the sewing machine. When the speed at which the sewing needle penetrates the work cloth is increased, the inertial force of the needle bar is increased, and the sewing needle can penetrate the work cloth that could not be easily penetrated in the past. Even when the needle bar descending speed is increased, the reciprocating motion of the needle bar itself is performed in the set number of cycles, so that sewing can be performed at a desired cloth feed speed.

[0006]

As described above, according to the present invention, it is possible to easily sew a work cloth, which has heretofore been difficult or impossible to sew, and to expand the range of sewable work cloth. Is obtained. Moreover, since it is not necessary to make the needle bar drive motor large-sized, it is possible to avoid making the entire device large-sized and to keep costs low.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 2, reference numeral 10 is a machine frame of the sewing machine, which includes an upper arm portion 12 and a lower bed portion 14. A needle bar base 16 is provided in the arm portion 12. The needle bar base 16 is a plate member extending in the vertical direction, and a pair of flange portions extending in the horizontal direction are formed at both upper and lower ends thereof. The upper flange portion extends further upward, and at this portion, the needle bar base 16 is swingably attached to the arm portion 12 by a pin 18. A through hole is formed in each of the flange portions, and the needle bar 24 is slidably fitted in the through hole. The needle bar 24 holds a sewing needle 26 at its lower end. Further, a slot 30 extending in the vertical direction is formed at the center of the needle bar base 16, and a pin 32 is engaged so as to be movable only in the longitudinal direction of the slot 30. The shaft portion of the pin 32 is fixed to the needle bar 24, and the pin 32 and the needle bar 24
And are designed to move together.

The head of the pin 32 is engaged with a notch 40 formed in the flange 38 of the rack member 36 so as to be movable only in the left-right direction. Further, a needle bar driving servomotor 42 is disposed near the rack member 36,
A rack portion 44 of the rack member 36 meshes with a pinion 46 that is attached to the rotation shaft of the servomotor 42 so as not to rotate relative to it. The servo motor 42 rotates in both forward and reverse directions, and the rack member 36 is moved up and down via the pinion 46 by the forward and reverse rotation of the servo motor 42, and the pin 32 engaged with the notch 40 of the rack member 36.
The needle bar 24 is supported by the needle bar base 16 via the and is reciprocated in the vertical direction.

A potentiometer 50 is also disposed in the vicinity of the rack member 36, and a pinion 52, which is fixed to the rotation shaft of the rack member 36 so as not to rotate relative to it, meshes with the rack portion 44. As shown in FIG. 3, the potentiometer 50 includes a computer 56 via an A / D converter 54.
Is connected to the input / output interface 58, and its output signal is digitally converted and input to the computer 56. An encoder 60 is connected to the rotary shaft of the servo motor 42, and the encoder 6
0 is also connected to the input / output interface 58, and its pulse signal is input to the computer 56.

The lower end of the needle bar base 16 is connected to a needle bar swinging pulse motor 66 (see FIG. 3) via a connecting rod 64, and the needle bar base 16 is driven by the pin 1 by driving the pulse motor 66.
The needle bar 24 and the sewing needle 26 are swung around 8 so that the needle bar 24 and the sewing needle 26 can be swung in the left-right direction.

A support shaft 70 is also arranged on the arm portion 12, and a sector gear 72 is rotatably supported. As is clear from FIG. 2, a balance 74 is formed at one end of the sector gear 72. In addition, the sector gear 72
A pulse motor 76 for driving the balance is disposed in the vicinity of the pinion 78, and a pinion 78 mounted on the rotation shaft of the balance motor so as to be relatively non-rotatable is meshed with a gear portion 80 of the sector gear 72. Therefore, the sector gear 72 is rotated around the support shaft 70 by both forward and reverse rotations of the pulse motor 76,
The balance 74 is reciprocally moved in the vertical direction.

A cloth retainer 82 is provided near the sewing needle 26. The cloth presser 82 is attached to the tip of a presser bar 84 extending parallel to the needle bar 24 with a screw 86, and the other end of the presser bar 84 is supported by a presser bar holder 88 in the arm portion 12. The presser bar hanger 88 is urged in the downward direction by a spring member (not shown), and is engaged with the cam surface 94 of the presser up lever 90 to define the lower end position thereof. The press-up lever 90 has a cam shape, and the pin 92 allows the machine frame 1
It is rotatably attached to 0. Therefore, by rotating the press-up lever 90 counterclockwise, the presser bar 84 is raised against the urging force of the spring member, and the cloth presser 82 is positioned at the non-acting position. On the other hand, by rotating the press-up lever 90 in the clockwise direction, the cloth presser 82 descends and is positioned at an operation position for pressing the work cloth.

Further, a potentiometer 98 (see FIG. 3) is arranged in the vicinity of the holding rod holder 88, and a pinion (not shown) mounted on the rotation shaft of the holding rod holder so as not to rotate relative to the other end of the holding rod holder 88. It is meshed with the gear part formed on the. In the state where the cloth presser 82 presses the cloth to be processed in the operating position, the height of the cloth presser 82 is different due to the difference in the thickness of the cloth to be processed. This cloth holder 82
Is detected by the potentiometer 98 via the presser bar holder 88 and the pinion. The potentiometer 98 is connected to the input / output interface 58 of the computer 56 via the A / D converter 100. The computer 5 based on the electric signal from the potentiometer 98
The thickness of the work cloth is calculated within 6.

A horizontal shuttle 106 is disposed in the bed portion 14. The outer hook 108 of the horizontal hook 106 is a support shaft 110.
It is rotatably supported by the bed 14 in the horizontal plane via. A gear portion 112 is formed on the outer peripheral surface of the outer hook 108, and is meshed with a pinion 116 which is attached to the rotary shaft of the hook driving pulse motor 114 so as not to be relatively rotatable. Therefore, the driving of the pulse motor 114 causes the outer pot 108 to rotate in a fixed direction.

A feed dog 120 is provided above the horizontal shuttle 106. The feed dog 120 is fixed to a feed base 122, and the feed base 122 is connected to one end of a front-rear feed lever 124. The front-rear feed lever 124 is the support shaft 12.
It is rotatably supported by the bed portion 14 via the gear 6, and a gear portion 128 is formed at the other end. Further, a pulse motor 130 for forward and backward feed is arranged in the bed portion 14, and a pinion 132 and a gear portion 128, which are attached to the rotation shaft thereof such that they cannot rotate relative to each other, mesh with each other. Therefore, the forward / reverse rotation of the pulse motor 130 causes the forward / backward feed lever 124 to rotate about the support shaft 126 as a fulcrum, and the feed dog 120 together with the feed base 122 to reciprocate forward and backward.

A vertical feed lever 136 is swingably attached to the bed portion 14 by a support shaft 138 near the front-back feed lever 124. A roller (not shown) is rotatably attached to one end of the vertical feed lever 136, and the outer peripheral surface of the roller is brought into contact with the bottom surface of the feed base 122. A gear portion 140 is formed at the other end of the vertical feed lever 136, and the vertical feed pulse motor 14 is provided.
Pinion 1 mounted on the rotating shaft of 2 so as not to rotate relative to it
It is meshed with 44. Therefore, the up-and-down feed lever 136 swings at a predetermined angle around the support shaft 138 by the forward and reverse rotations of the pulse motor 142, and the feed platform 122 is reciprocated in the up-and-down direction by the roller with a required stroke.

The machine frame 10 is further provided with a start / stop button 1
48 and numeric keypad pattern selection buttons (see Fig. 3) 1
50 are provided. The pattern selection button 150 is for selecting a desired sewing pattern.

The control system of the sewing machine of this embodiment is shown in FIG.
As is apparent from the figure, the servo motor 42 and the pulse motors 66, 76, 114, 130, 142 are connected to the input / output interface 58 of the computer 56 via the drive circuits 154-164. Also, start
Start / stop switch 170 corresponding to the stop button 148
Is provided and is connected to the input / output interface 58. The start / stop switch 170 is alternately turned on and off each time the operator operates the start / stop button 148 once.
It is a state. The pattern selection button 150 is 10
One pattern selection switch 172 is provided corresponding to each pattern selection button 150, and is connected to the input / output interface 58.

The computer 56 includes an input / output interface 58, a CPU 176, a ROM 178, and a RAM 18.
0, which are connected by a bus 182. The ROM 178 includes a program memory 186 and a stitch pattern data memory 188. The stitch pattern data memory 188 stores stitch pattern data corresponding to each of the stitch patterns selectable by the pattern selection switch 172, and the program memory 186 stores each motor based on the stitch pattern data. Control programs for controlling each of the above, a stitch formation control program represented by the flowcharts of FIGS. 4 to 6, an output data table corresponding to the set speed of the servo motor 42, a pulse corresponding to the set speed of each pulse motor 66, 76, etc. A number table etc. are stored. Further, the RAM 180 is provided with various memories for temporarily storing the calculation processing result of the CPU 176, a timer T ₁ and a flag F ₁ shown in FIG.

The stitch formation control in the sewing machine constructed as described above will be described with reference to the flow charts of FIGS. The stitch formation control program is executed by the main routine of FIG. 4 for controlling the overall timing, the cycle number control routine of FIG. 5 for controlling the number of cycles of the needle bar 24, and the interrupt of the encoder 60 when the pulse falls, and the needle bar 24. The needle bar speed control routine of FIG. The number of cycles of the needle bar 24 is set to 200 cycles per minute (1 cycle time = 300 msec).

At the same time when the power is turned on, the main control shown in FIG. 4 is started. First, in step S1 (hereinafter, simply represented by S1; the same applies to other steps), initialization is performed, and the flags F ₁ , F _{2 and the} like are turned off. Further, the initial position control is performed, and the needle bar 24, the outer hook 108, the balance 74, etc. are positioned at the initial position by the respective drive circuits and motors. The needle bar 24 and the like are maintained in this initial position except when sewing.

Next, in S2, the start of sewing is awaited.
If the start / stop button 148 is pressed by the operator, the start / stop switch 170 is turned on, so the result of the determination is YES, the timer T ₁ is reset in S3, and the cycle shown in the flowchart of FIG. The number control process is started. This cycle number control process is executed by an interrupt every 1 msec. In S101, the count value n is incremented by 1 to obtain the count value n
Until the number reaches 300, the determination result of S102 becomes NO, S103 and S104 are skipped, and one execution ends. Then, when n = 300, the determination result of S102 is YES, and the start flag F ₁ is turned on in S103. Then, the count value n is reset to 0 in S104. That is, the timer T
_{Since the} start flag F ₁ is turned on every 300 msec after the start of ₁ , the start / stop switch 170 is turned off in this cycle number control process,
It continues until the timer T ₁ is stopped in S24.

After execution of S3, the output value of the potentiometer 98 is read and the thickness of the work cloth is detected in S4. Before the start / stop switch 170 is operated, the presser lever 90 is rotated clockwise by the operator to lower the cloth presser 82 to the operating position.
Presses the cloth to be processed placed on the bed portion 14, and the output value of the potentiometer 98 indicating the height of the cloth presser 82 in that state is read. If the read thickness of the work cloth is 2 mm or more, the determination result of S5 is YES, and the speed change flag F ₂ is turned on in S6.
It is said that. On the other hand, if the thickness of the work cloth is less than 2 mm, S
The judgment result of 5 is NO, and the speed change flag F ₂ is ON.
Not be That is, in the present embodiment, "the thickness of the work cloth is 2 mm" is the criterion for determining whether or not the descending speed of the needle bar 24 needs to be increased. Since it is difficult to penetrate the cloth to be processed, it is determined that it is necessary to increase the descending speed of the needle bar 24, and the speed change flag F ₂ is turned on.

In this embodiment, the cloth retainer 82, potentiometer 98, A / D converter 100, CPU 176.
The part that executes S4, S5, and S6 of the main routine of the above constitutes the need for increasing the needle bar lowering speed.

Subsequently, in S7, a drive command signal is output to the drive circuit 154, the servomotor 42 is activated to start the lowering of the needle bar 24, and in S8, the interrupt of the pulse signal of the encoder 60 is permitted. To be done. After that, it is waited for the position of the needle bar 24 detected by the potentiometer 50 to descend to the speed change start height in S9. In the present embodiment, the speed change start height is determined at point A in FIG. When the height of the needle bar 24 reaches the speed change start height, the determination result of S9 is YES, and it is determined whether or not the speed change flag F ₂ is turned on in S10. If the speed change flag F ₂ is turned on in S6, the determination result is YES, and the speed change start position flag F ₃ is turned on in S11.
However, if the speed change flag F ₂ remains OFF, the determination result of S10 is NO, S11 is skipped, and S12 is executed.

After the execution of S8, the needle bar speed control routine shown in FIG. 6 is executed once by interruption in response to the fall of the pulse signal from the encoder 60. First, in S201, the time interval of the falling signal is measured, and the speed of the needle bar 24 is calculated from the time interval. Then, increases in S202, it is determined the speed change start position flag F ₃ of whether it is turned ON is performed, if the decision result is YES, the speed at which the target speed of the needle bar 24 is predetermined at S203 To be made. Then S
After 204 speed change start position flag F ₃ in is the OFF, in S205, a target speed set current speed and the computed needle bar 24 are compared in S201. At first, immediately after the speed change start command is issued, the current speed becomes lower than the target speed, and the speed increasing process is performed in S206. The drive current of the servo motor 42 from the drive circuit 154 is increased by an amount proportional to the difference between the target speed and the current speed.

At the next interruption of the pulse signal of the encoder 60, the determination result in S202 is NO, and it is determined in S207 whether the speed change end flag F ₄ is ON. If the speed change end flag F ₄ is not turned on in the main routine, the determination result is NO.
Then, S208 to S210 are skipped and S2 is executed again.
At 05, the current speed of the needle bar 24 is compared with the target speed. If the current speed has reached almost the same speed as the target speed by the previous execution of S206, the execution of the program ends as it is, but if it has not reached the target speed yet, the speed-up processing is performed again in S206. Also,
If the current speed has already exceeded the target speed, S21
In step 1, the deceleration process is performed, the drive current of the servo motor 42 is reduced, and the descending speed of the needle bar 24 is reduced. After that, S201, S
202, S207, S205 are repeatedly executed, S206 or S211 is performed according to the current speed of the needle bar 24, and the needle bar 24 is lowered at a speed higher than usual as shown in FIG.

In this embodiment, the servo motor 42,
The portion that executes the needle bar speed control routine of the encoder 60, the drive circuit 154 and the CPU 176 constitutes the needle bar speed control means.

In the main routine, S12 is repeatedly executed after S11, and it is waited for the height of the needle bar 24 to reach the speed change end position based on the output signal of the potentiometer 50. The speed change end position is set to the position of point B in FIG. 8 in which the sewing needle 26 has descended by a certain amount after penetrating the work cloth. If the needle bar 24 descends to the speed change end position, the determination result of S12 is YES and S
At 13, it is determined whether or not the speed change flag F ₂ is turned on. If the determination result is YES, S1
4, the speed change end flag F ₄ is turned on, and if the determination result is NO, S14 is skipped and S15 is executed.

If the speed change end flag F ₄ is turned on, the determination result of S207 is YES in the needle bar speed control routine of FIG. 6, and the target speed is reduced to the normal speed in S208. Then, in S209, the speed change flag F ₂ is turned off, and S2
After the speed change end flag F ₄ is turned off in 10, the current speed of the needle bar 24 and the target speed are compared in S205. Since the target speed is decreased, the current speed becomes higher than the target speed, and the deceleration processing of S211 is executed. Therefore, the drive current supplied from the drive circuit 154 to the servo motor 42 is reduced, and the descending speed of the needle bar 24 is reduced. Then S
201, S202, S207 and S205 are executed, and depending on the speed of the needle bar 24, S206 or S211 is executed.
Is executed, and the needle bar 24 returns to the state of being lowered at the normal speed again as shown in FIG.

While the needle bar 24 is being lowered, the lowest point,
That is, when the point C shown in FIG. 8 is reached, the determination result of S15 of the main routine is YES, and a needle bar lift start command is issued in S16. Therefore, the drive circuit 15
4, the servo motor 42 is driven in the opposite direction, and the needle bar 2
4 is raised. Subsequently, in step S17, a shuttle drive start command is issued, and the drive circuit 160 starts to supply the shuttle drive pulse motor 114 with a pulse current corresponding to one rotation of the outer shuttle 108. As a result, the pulse motor 114
Is started, and the rotation of the outer pot 108 is started. Needle bar 24
The upper thread of the upper thread (not shown) inserted through the sewing needle 26 is formed by the rising of the sewing needle 26, the outer thread 108 is caught by the rotation of the outer hook 108, and then the outer hook 108 is rotated once to rotate the upper thread. And the lower thread are entangled with each other to form a stitch on the work cloth. After one rotation of the outer pot 108, the pulse signal to the pulse motor 114 is cut off, so that the driving of the pulse motor 114 is stopped and the outer pot 108 is stopped at the initial position.

In S18, it is waited for the needle bar 24 to reach the uppermost point, that is, the point D shown in FIG. 8. If the determination result in S18 is YES, a needle bar drive stop command is issued in S19 and the needle bar is stopped. 24 is stopped in the raised end position. Subsequently, in S20, the pulse interruption of the encoder 60 is prohibited, and the execution of the needle bar speed control routine is stopped. Then, in S21, whether or not the start flag F ₁ is ON, that is, whether or not the count value n has reached 300 in the cycle number control routine, in other words, 300 msec has elapsed from the start of descending the needle bar 24. Whether or not it is determined. If the determination result in S21 is NO, in S22, the operator presses the start / stop button 148 again, and the start / stop switch 17 is pressed.
It is determined whether 0 is turned off. If the start / stop switch 170 remains in the ON state, the determination result is NO.
Then, S21 is executed again.

After the lapse of 300 msec, if the start flag F ₁ is turned on in the cycle number control routine, S2
After the determination result of 1 is YES and the start flag F ₁ is turned off in S23, the program is executed in S4.
Then, the next stitch is formed.

In this embodiment, as is clear from the descending state of the needle bar 24 shown by the solid line in FIG. 8 and the descending state of the normal needle bar shown by the alternate long and short dash line, the descending speed of the needle bar 24 is increased. As a result, even if the needle bar 24 reaches the rising end position earlier than usual, the next lowering of the needle bar 24 is not performed until 300 msec has elapsed. That is, despite the increase in the descending speed of the needle bar 24 during the descending operation, the needle bar 24 can be reciprocated up and down once in 300 msec, and the needle bar 24 is set to exactly 200 cycles per minute. It can be reciprocated in the number of cycles.

On the other hand, the operator activates / stops the button 14
When 8 is pressed to turn off the start / stop switch 170, the determination result of S22 is YES, and the execution of the cycle number control routine is stopped in S24.
Then, the execution of the program returns to S2, and it is waited for the start / stop button 148 to be pressed again.

As is apparent from the above description, in the present embodiment, as shown in FIG. 8, after the needle bar 24 is started to descend, the needle bar 24 ends the speed change from the speed change start position A. The descending speed is increased while reaching the position B. Since there is a time interval between the AB where the tip of the sewing needle 26 penetrates the work cloth, the large inertia force generated by increasing the speed of the needle bar 24 causes the sewing needle 26 to change the thickness of the work cloth. It can overcome large load resistance and penetrate well.

Further, in the present embodiment, the speed at which the needle bar 24 is accelerated causes the time to reach the lowest point C to be earlier than usual, but the computer 56 causes the balance 7 to move.
4, the driving of the outer hook 108, the feed dog 120, and the like are controlled according to the descending timing of the needle bar 24, so that sewing can be performed without any trouble.

After accelerating the speed of the needle bar 24, the descending speed is decelerated from the normal descending speed so that the lowest point C is reached at the same time as in the normal case where the accelerating is not performed. Stick 24
It is also possible to control the speed of the sewing machine, and by doing so, the sewing machine can be operated almost at the set number of cycles even if the cycle number control routine of FIG. 5 is omitted.

Further, in the present embodiment, the descending speed of the needle bar can be changed only in two steps, but it can be changed in multiple steps, and the thickness of the work cloth can be changed. It is also possible to change continuously according to the above.

Further, in this embodiment, the encoder 6
Although the speed of the needle bar 24 is detected by the interval of the pulse falling signal of 0, it can be detected by the rising signal. Further, instead of the encoder 60, the speed of the needle bar 24 can be directly detected by a tacho generator, and the speed can be detected by differentiating the output signal of the potentiometer 50.

On the contrary, the encoder 60 is replaced with an absolute encoder capable of detecting the absolute position of the needle bar and the potentiometer 50 is omitted, or the encoder 60 and a photoelectric switch for detecting the arrival of the needle bar 24 at the rising end are used. It is also possible to detect the position of the rod 24.

In the present embodiment, the criterion for determining whether or not it is necessary to increase the descending speed of the needle bar 24 is "the thickness of the work cloth is 2 mm", but the sewing needle It is also possible to measure the descending speed of the needle bar immediately after penetrating the work cloth, and if the speed is below a reference value, it may be necessary to increase the descending speed.

Furthermore, it is also possible to set other characteristics such as "fine texture of the work cloth is fine" as a necessary condition for increasing the descending speed, and a detecting means for detecting the setting condition is provided,
The speed of the needle bar 24 may be controlled.

Also, as in this embodiment, the needle bar 24
In the sewing machine in which the vertical movement of the sewing machine is performed by the engagement between the rack member 36 and the gear 46 of the servo motor 42, the sewing needle penetrates the work cloth as compared with a sewing machine in which the needle bar is vertically moved by using a crank mechanism. Since the speed at the moment of doing so is small, by applying the needle bar control device of the present invention, the penetrating force of the work cloth of the sewing needle 26 is significantly increased, but the present invention is applied to a sewing machine having a crank mechanism. It is also possible to apply.

Besides, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a diagram conceptually showing a configuration of the present invention.

FIG. 2 is a perspective view showing a main part of a sewing machine including a needle bar control device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a sewing machine including the needle bar control device, centering on an electronic control unit.

FIG. 4 is a flowchart showing a main routine stored in a ROM of the computer of the sewing machine.

FIG. 5 is a flowchart showing a cycle number control routine stored in a ROM of the computer.

FIG. 6 is a flowchart showing a needle bar speed control routine stored in a ROM of the computer.

FIG. 7 is a block diagram showing a configuration of a RAM of the computer.

FIG. 8 is a graph showing the vertical movement of the needle bar controlled by the needle bar control device together with the vertical movement of a normal needle bar.

[Explanation of symbols]

 24 needle bar 26 sewing needle 42 needle bar drive servo motor 56 computer 60 encoder 82 cloth retainer 98 potentiometer 100 A / D converter 154 drive circuit

Claims (1)

Claim: What is claimed is: 1. A needle bar control device for a sewing machine, which reciprocates a needle bar, which holds a sewing needle at a lower end thereof, in a vertical direction at a set number of cycles by a needle bar drive motor. If there is a need for the detection result of the increase necessity detection means and the increase necessity detection means for detecting the presence or absence of the necessity of the sewing machine, at least the tip of the sewing needle is processed without changing the set number of cycles. A needle bar speed control means for increasing the operating speed of the needle bar drive motor at the time when the cloth penetrates the needle bar control device.