JP2002336582A - Sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely perform only thread cutting operation when requiring no operation of a cloth pressing-down device in a sewing machine using a thread cutting means and a driving source of a pressing-up means in common. SOLUTION: This sewing machine 100 has a thread cutting/pressing-up device 10 for cutting thread and lifting the cloth pressing-down device 7 for pressing down cloth; a pressing-up solenoid 1 for driving the thread cutting/pressing-up device 10 for successively performing thread cutting and press-up by operating at a prescribed stroke from an initial state; a midway thread cutting sensor 58 for detecting a working speed of the pressing-up solenoid 1; and a CPU 53 for controlling and driving the pressing-up solenoid 1 by driving force after selecting the driving force of the pressing-up solenoid 1 for cutting the thread, and performing no press-up on the basis of the working speed detected by the midway thread cutting sensor 58.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a thread cutting means,
The present invention relates to a sewing machine including a presser lifting device that raises a cloth presser device.

[0002]

2. Description of the Related Art Conventionally, a sewing machine is provided with a thread cutting means for cutting a thread and a press-up means for raising a cloth presser device, wherein the thread cutting means and the press-up means are driven by a common drive source. It has been known. In such a sewing machine, after sewing, following the thread cutting operation by the thread cutting means,
The presser lifting means drives the cloth presser device upward. In the case where only the thread trimming is performed and the cloth is not desired to be moved, the drive source is appropriately controlled so that only the thread trimming means operates and the cloth presser does not move up.

Specifically, a conventional control method in such a case will be described with reference to FIG. Here, a description will be given assuming that a solenoid is used as a common drive source for the thread cutting means and the presser lifting means. FIG. 8 shows a timing chart of control when only thread trimming is performed using a solenoid. In FIG. 8, the upper position detection signal is a low active signal for detecting that the sewing needle has reached the top dead center. The thread trimming solenoid drive output signal and the sewing machine stop signal are control signals output from a control circuit of the sewing machine. In this control, when it is detected from the upper position detection signal that the top dead center just before the last needle drop has been reached, the time (A
Start counting time from point). Then, after a predetermined time B has elapsed, the sewing machine motor is stopped at the point C, and the drive output signal to the common solenoid of the thread trimming means and the presser raising means is turned ON (high). After ON, the solenoid is driven with a duty ratio of 100%, that is, full power, and then reduced to a duty ratio of 50% for D time.
After the lapse of time, the output is turned off (low). in this way,
By setting the full power for the first predetermined time (D time) after the solenoid is turned on, and then reducing the duty ratio,
The solenoid cannot extend the stroke to a certain extent, and remains in a state of exerting a relatively weak force. Accordingly, it is possible to perform control so that only the thread trimming is performed, the presser lifting means is not operated, and the cloth presser is not raised.

[0004]

However, in the conventional sewing machines, the time D and the time E in FIG. 8 are fixed. By the way, there is a variation in the output exerted for each individual product due to a difference between the products of the power supply and the solenoid itself, a variation in assembling, and the like. Further, even with one product, the same output cannot always be exerted every time. Therefore, if the signal for driving the solenoid is fixed in time, there is a problem that the solenoid may not be controlled as designed. That is, when the actual output is larger than the design, even when only the thread trimming is to be performed, the presser lifting means is operated, the cloth presser device is raised, and the fabric is displaced. On the other hand, if it becomes smaller, the solenoid stops before the thread trimming operation is completed, and a thread trimming defect occurs. Such a problem is not limited to the case where a solenoid is used, and even if other types of solenoids, motors, cylinders, and the like are used, the problem always occurs if the control is performed in a fixed manner. In order to solve the above problem, it is conceivable to separately provide a drive source for the thread cutting means and the presser lifting means, or to use a two-stage solenoid capable of precise control, but these methods are costly. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sewing machine in which the drive source of the thread trimming means and the presser lifting means is common, and when the operation of the cloth presser is unnecessary, only the thread trimming operation is performed reliably and at no cost. Is to be able to perform.

[0006]

Means for Solving the Problems To solve the above problems, the invention according to claim 1 is a thread cutting means for cutting a thread as shown in FIGS. 1 to 3, 6, and 7, for example. (Thread trimming / lifting device 10), presser lifting means (thread trimming / lifting device 10) for raising the cloth presser device (7) for holding the cloth, and a thread operated by a predetermined stroke from the initial state. In a sewing machine (100) including a driving means (presser lifting solenoid 1) for driving a cutting means and thereafter driving a presser lifting means, a detecting means (intermediate thread trimmer sensor 58) for detecting an operation speed of the driving means; The drive means drives the thread cutting means based on the operation speed detected by the means, and the drive condition acquiring means (CPU 53) for acquiring the driving conditions when the presser lifting means is not driven. Work when it is not necessary, in the obtained drive condition by the driving condition acquisition unit, characterized in that it comprises a control means for controlling the drive means (CPU 53).

According to the first aspect of the present invention, when the driving means drives the thread cutting means and the presser lifting means does not drive, the driving condition acquiring means determines the operating speed of the driving means detected by the detecting means. The driving condition is obtained, and the driving unit is controlled by the driving condition acquired by the driving condition acquiring unit under the control of the control unit. Therefore, since the driving unit is driven under the driving condition of performing only the thread trimming obtained based on the actual operation speed, even if there is a difference in the ability exerted by the driving unit due to a variation between products or operations, Only the thread trimming is surely performed. In addition, new driving means and the like are not provided and expensive components are not used, and only the detecting means is provided, so that the cost hardly increases.

Here, as the driving means, a solenoid, a cylinder, a motor or the like can be used. "Operates with a predetermined stroke from the initial state" means that when turned ON from the initial state when OFF, for example, a solenoid or a cylinder operates linearly at a predetermined distance or a motor rotates at a predetermined angle. That is to say. The “drive condition” refers to the drive force, drive speed,
Driving time. Further, “acquire” may be selected from data set in advance based on the detection result, or may be obtained by calculation. As the detection means, for example, various sensors such as an optical sensor, a magnetic sensor, or a mechanically operated sensor can be used. Further, the number of the detecting means is not limited. Further, the detection by the detection unit and the acquisition of the drive condition by the drive condition acquisition unit may be performed only when the operation of the presser lifting unit is unnecessary and only the thread trimming is desired, or the drive unit operates. It may be configured to always perform it.

According to a second aspect of the present invention, in the sewing machine according to the first aspect, the detecting means is a member (presser lift) interlocked with the operation of the driving means from the initial state to the driving of the thread cutting means. Link 4). According to the second aspect of the present invention, when the driving means starts to move, the detecting means is provided on a member which is interlocked with the driving means. Since the detecting means is provided on the member for transmitting the movement of the means, the structure is not complicated even if the detecting means is provided, and the cost can be reduced in this respect as well. Here, the "linked member" means, for example, if the driving means is a solenoid, a motor, or a cylinder, those output shafts or members connected to the output shaft, and the "linked member" moves linearly. Or rotation or rotation.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a sewing machine 100 which is a sewing machine with a single-ring stitch button. Sewing machine 100
Is mainly composed of an arm 101, a bed 102 and a vertical trunk 103. In FIG. 1, a part of the arm part 101 and the vertical trunk part 103 is shown in a see-through state. An upper shaft 106 is provided in the arm portion 101, and a needle bar 104 is attached to the upper shaft 106.
A sewing needle 105 is fixed to a lower end of the sewing machine. Upper shaft 106
Is driven by a sewing machine motor 59 (FIG. 2) via a link 107, whereby the sewing needle 105 moves up and down.

The sewing machine 100 includes a control device 50 shown in FIG.
Sewing machine motor 59 connected to the control device 50,
A push-up solenoid 1 and the like are provided, and buttons are automatically attached. FIG. 2 shows a configuration necessary for explaining the present invention, and the sewing machine 100 includes other various sensors (not shown), a motor, an operation panel 60, and the like. The control device 50 includes a CPU (Central Process).
ssing Unit) 53, RAM (Random)
Access Memory) 54 and ROM (R
A head-only memory 55 is provided. The ROM 55 stores various control data and programs. The RAM 54 stores data input from the operation panel 60, calculation results, and the like, and also stores data necessary for a presser lifting solenoid control process described later. Further, the sewing machine 100 generates sewing data based on various sewing conditions set via the operation panel 60 and the like, and the RAM 54 also stores the sewing data. The sewing data includes, for example, data on the number of needles to be sewn and thread tension. The upper position sensor 52 includes a needle bar 104
It detects that the (sewing needle 105) is located at the top dead center, and outputs an upper position detection signal to the CPU 53. The halfway thread trimming sensor 58 is provided in a thread trimming / pressing device 10 described later, and outputs a halfway thread trimming detection signal to the CPU 53. The activation pedal 51 is a switch for activating the sewing machine motor 59, and outputs an activation signal to the CPU 53 when the operator operates the switch.

The CPU 53, which is a driving condition acquisition unit and a control unit of the present invention, performs various processes based on information input from the ROM 55 and the RAM 54 and signals from the sensors 52 and 58 to form various devices constituting the sewing machine 100. Control drive. Specifically, for example, when a start signal is input from the start pedal 51, the sewing machine motor 59 is started via the drive circuit 56, and the presser lifting solenoid 1 is driven at a predetermined timing at the end of sewing. Details of the presser lifting solenoid 1 and the halfway thread trimming detection signal will be described later.

FIG. 3 shows a thread cutting / pressing device 10 of the sewing machine 100. This thread cutting / lifting device 10
Performs the thread trimming operation and the cloth presser 7 (FIG. 1)
Is to increase. Thread cutter / lifter device 10
Has a presser lifting solenoid 1 (driving means) fixed inside the sewing machine 100. Presser lifting solenoid 1
Operates under the control of the CPU 53 via the drive circuit 57, and exerts the load characteristics shown in FIG. In FIG. 4, the horizontal axis represents the stroke of the plunger 1a, which is the output shaft of the solenoid 1, and the vertical axis represents the load output (force exerted on the load) corresponding to the stroke.
Is shown. The characteristics of the presser-lifting solenoid 1 largely change at a stroke of 9 mm, that is, the inclination is small before 9 mm and a relatively small force is exerted, and when the stroke exceeds 9 mm, the inclination is sharp and a large force is exhibited. .

One end of a press-up link 4 formed in a horizontally long flat bar shape is fixed to an end of the plunger 1a. One end of the first spring 2 is hung on the other end of the press-up link 4, and the other end of the first spring 2 is hung on a pin 20 fixed in the sewing machine. As a result, the presser link 4 is urged by the first spring 2 in the direction of arrow R in FIG. 3, and comes into contact with the stopper 3 in the sewing machine and is stopped.

An intermediate thread cut sensor 58 is provided below the center of the presser link 4. The intermediate thread trimming sensor 58 is formed by fixing a photo interrupter 58b formed in a U-shape on a base 58a. The base 58a is fixed in the arm 101. On the other hand, a pass-through member 4a made of a flat metal having an inverted convex shape and capable of passing between U-shaped photointerrupters 58b is screwed to the press-up link 4. This passing member 4a
Is mounted such that when the presser lifting solenoid 1 is in the OFF state, it is located a predetermined length ahead of the intermediate thread trimming sensor 58. When the link 4 is turned on and the press-up link 4 is pulled backward, the passing member 4a also moves backward, and passes between the photointerrupters 58b on the way. For example, the lifting link 4 is 5m
m, the passing member 4a is
8b. The passing member 4a
Since the photointerrupter 58b receives the reflected light when the passing member 4a has passed, it transmits a signal to that effect to the CPU 53. In response to this, the CPU 53
Recognizes that the stroke of the presser lifting link 4, that is, the presser lifting solenoid 1, has reached 5 mm. The detection signal from the intermediate thread trimming sensor 58 is detected earlier as the output of the presser lifting solenoid 1 is relatively large with respect to the load and the movement of the presser lifting link 4 is faster. That is, the intermediate thread trimming sensor 58 serves as the detecting means of the present invention.

One end of a lifting lever 5 is rotatably connected to the front of the lifting link 4. The presser lifting lever 5 has a substantially U shape, and is rotatably attached to the sewing machine frame at a bent portion thereof. The other end of the presser lifting lever 5 is provided with a protruding portion 5a that protrudes laterally. At the rear end of the presser foot device 7, the feed shaft 108 on the bed 102 is attached to the mounting shaft 7b.
, And can swing up and down around the mounting shaft 7b. A button clamp (not shown) for supporting the button when attaching the button is provided at the front end of the cloth presser 7.
Is provided. A needle plate 12 fixed on the bed 102 is provided below the button clamp.

The lower end of the second spring 15 is locked at the center of the cloth presser 7 (FIG. 1). The upper end of the spring 15 is locked in the sewing machine frame, and the entire cloth presser 7 is pressed downward by the second spring 15. Thus, the cloth is sandwiched and pressed between the button clamp and the needle plate 12. The second spring 15 has a considerably stronger urging force than the first spring 2. An L-shaped hook 7a is fixed to the cloth presser 7. A gap of a predetermined length is provided in the vertical direction between the hook 7a and the protruding portion 5a of the presser lifting lever 5, and the presser lifting lever 5 rotates counterclockwise in FIG. When it rises by a predetermined length,
It comes into contact with the hook 7a.

On the other hand, one end of a thread cutting lever 6 is rotatably connected to a rear portion of the presser lifting link 4. The thread cutting lever 6 is formed in a shape in which the dogleg is turned upside down, and is rotatably attached to the sewing machine frame at a bent portion thereof. The other end of the thread cutting lever 6 has a cam roller 6
a is protruding. A thread cutting arm 8 is provided beside the thread cutting lever 6. The upper end of the thread cutting arm 8 is rotatably attached to the sewing machine frame. A cam hole 8a is formed in the thread cutting arm 8, and the cam roller 6a is fitted into the cam hole 8a. An L-shaped connecting plate 9 is attached to the lower end of the thread cutting arm 8 via a connecting pin 22. The thread cutting arm 8 and the connecting plate 9
The connection pins 22 are rotatable with each other.

One end of a first thread cutting link 21 is rotatably attached to the connecting pin 9.
Is fixed to one end of a second thread cutting link 23. The front end 23a of the second thread cutting link 23 faces the back side of the needle plate 12, as shown in FIG. 3, and the moving knife 13 is rotatably mounted. The moving knife 13 is also rotatably attached to the needle plate 12 via pins 23.
On the back side of the needle plate 12, a fixed knife 14 is further fixed.

The needle plate 12 has a sewing hole 25 through which a sewing needle 105 passes. After the sewing is completed, the thread connected to the sewing needle 105 passes through the sewing hole 25 and is sewn on the fabric in a loop between the fixed knife 14 and the moving knife 13. When the moving knife 13 rotates counterclockwise in FIG. 3 around the pin 23, the moving knife 13 meets the fixed knife 14,
The thread is cut.

In the sewing machine 100, the button is sewn on a cloth sandwiched between the button clamp and the needle plate 12 while the button is sandwiched between the button clamps. 10 operates as follows. That is, the push-up solenoid 1 is
N, whereby the plunger 1a moves in the direction P in FIG. 3 against the urging force of the first spring 2. As a result, the presser foot link 4 is retracted, and the thread trimming lever 6 and the presser foot lever 5 start rotating counterclockwise. When the thread trimming lever 6 rotates, the first thread trimming link 21 and the second thread trimming link 23 move in the Q direction via the thread trimming arm 8,
As a result, the moving knife 13 rotates counterclockwise in FIG. 3, and cuts the thread between the fixed knife 14 and the moving knife 13.

During this thread trimming operation, the presser lifting lever 5 also rotates counterclockwise, and the protrusion 5a moves upward, but initially the protrusion 5a and the hook 7 are moved by the play distance.
a does not engage. Almost simultaneously with the completion of thread trimming, the protrusion 5a
And the hook 7a are engaged with each other, the hook 7a is pushed up by the protrusion 5a against the urging force of the second spring 15, and the cloth presser device 7 rotates upward around the mounting shaft 7b,
When the presser lifting link 4 stops at a predetermined position, the cloth presser device 7 also stops rotating. In this state, the buttons and the fabric can be removed. When the presser foot device 7 is lifted (pressing operation), the thread cutting lever 6 continues to rotate by the movement of the presser foot link 4 in the P direction. The rotation is not transmitted. When the presser lifting solenoid 1 is turned off, the thread cutting / pressing device 10 returns to the original state by the urging force of the first spring 2 and the second spring 15.

As can be seen from the above, of the series of thread trimming / pressing operations, the first thread trimming operation is against the first spring 2 which is a relatively weak spring. On the other hand, the presser lifting operation is a work against the strong second spring 15 and also lifts the entire cloth presser device 7, and requires much stronger force than the thread cutting operation. Therefore, in the thread cutting / pressing device 10, since the solenoid 1 has the load characteristics shown in FIG. 4, thread cutting is performed until the stroke of the plunger 1a reaches 9 mm. It is configured to raise the device.
The CPU 53 drives and controls the push-up solenoid 1 with a pulse voltage. In this case, the applied voltage is fixed,
By changing the off ratio (duty ratio) or changing the time of a predetermined duty ratio, the stroke of the solenoid 1, that is, the driving force, is controlled so that thread trimming and press-up are performed continuously, or only thread trimming is performed. I'm trying to do it.

In the above, the operation of the thread trimming and presser lifting device 10 after the completion of sewing has been described. However, if necessary, control is performed such that only thread trimming is performed without performing presser lifting. For example, when a four-hole button is sewn to a fabric, a stitch is first formed in two holes, and the thread is once cut here. Then the other two
In this case, a stitch is formed in a hole. In such a case, only the thread trimming operation is performed between the first sewing and the next sewing because the presser lifting operation is unnecessary. FIG. 5 shows the control timing in this case. The timing chart of FIG. 5 is substantially the same as that of FIG. 8, but differs in that a halfway thread trimming detection signal from the halfway thread trimming sensor 58 is adopted. In the sewing machine 100, the solenoid 1 is controlled based on the mounting position of the intermediate thread trimming sensor 58, the characteristics of the solenoid 1, and the like.
Stores the standard time data of the time (F time) from the point C when the sensor is turned on to the time when the sensor 58 outputs the signal, and the time from the point C until the halfway thread cut detection signal is actually detected. It is designed to measure.

The CPU 53 compares the data of the standard time of the time F in FIG. 5 with the actually measured values, and drives the solenoid 1 at the standard D time, the E time and the duty ratio if they are almost the same. Here, the standard time from when the presser lifting solenoid 1 is turned on until it is detected by the thread trimming sensor 58 in the middle is 65 to 75 milliseconds, which is detected during driving at full power (100 duty). Is done. Also,
The standard value (initial value) of the D time is set to 100 ms, and the E time is set to 140 ms.

If there is a difference between the standard time data and the measured value,
Depending on the degree of the difference, immediately, D time for driving with full power, E time for driving with a duty ratio of 50%, and E time
At least one of the time duty ratios is changed, and the solenoid 1 is controlled according to the changed data. A specific change value is selected from a plurality of preset data tables in accordance with the degree of difference between the standard time data and the actual measurement value, and is based on the selected value. As a type of the table, a "load extra small table" for a case where the load is very small with respect to the force of the solenoid 1 and the actually measured value is less than 50 milliseconds, "Small load table" when milliseconds, "Large load table" when the load is slightly large and the actual value is 75 to 90 milliseconds, the load is very large and the actual value exceeds 90 milliseconds The "extra large load table". These data tables are stored in RAM
54.

FIGS. 6 and 7 show the flow of the presser lifting solenoid control process when only the thread trimming is performed. This processing is started during sewing. First, in step S1, it is determined whether or not the sewing needle 105 is at the upper position based on a signal from the upper position sensor 52. If the upper position sensor 52 is turned on, the process proceeds to step S2. Transition. In step S2, it is determined whether or not it is one stitch before the last stitch. If it is one stitch before, the process proceeds to step S3; otherwise, the process returns to step S1.
In step S3, counting for outputting an output signal for driving the presser lifting solenoid 1 is started (point A in FIG. 5). This counting is performed based on the rotation angle using, for example, a rotary encoder. Next, step S
In step 4, it is repeated whether or not it is the timing to output a drive signal to the presser lifting solenoid 1 for the count started in step S3, and when the predetermined timing is reached, the process proceeds to step S5.

In step S5, the duty ratio is 100%
The initial value (10
Set the timer at 0 ms). Further, step S
In step 6, the timer is set with an initial value (140 milliseconds) that is set as a standard for driving at a duty ratio of 50%. Then, in step S7, a drive signal of full power (duty ratio 100%) is output to the presser lifting solenoid 1 to turn it on (point C in FIG. 5). at the same time,
In step S8, the timer set in step S5 is started. At substantially the same time, in step S9, when the presser lifting solenoid 1 is turned on, the intermediate thread trimming sensor 58
Starts a timer to measure the time until detection by.

Next, in step S10, it is determined whether or not the intermediate thread trimming sensor 58 has been turned ON. If it is not ON, the process proceeds to step S11, where it is determined whether or not the timer time set in step S5 has expired. If not, the process returns to step S10. ), Perform error processing such as error display, and terminate this flow. Step S1
When the intermediate thread trimming sensor 58 is turned on at 0, the flow goes to step S1
In step 2, the timer started in step S9 is stopped, and a measurement time X from when the presser-lifting solenoid 1 is turned ON to when the thread trimming sensor 58 detects the halfway is obtained.

Next, at step S13, X is 5
It is determined whether it is 0 ms or less. If not, the process proceeds to step S17; otherwise, the process proceeds to step S14. In step S14, the "load special small table" is compared with the actually measured value. Then, based on the comparison in step S14, in step S15, the 10 set in step S5 is set.
The timer time of 0% duty is reset, and in step S16, the timer time of 50% duty ratio set in step S6 is reset. When the load is very small, for example, 100% duty and 50%
Each time of the% duty is set shorter than the initial value.
Thereafter, the process proceeds to step S31 (FIG. 7).

In step S17, X is 50.
It is determined whether the time is within the range of milliseconds to 65 milliseconds. If it is within the range, the process proceeds to step S18, and if it is out of the range, the process proceeds to step S21. In step S18, the "low load table" is compared with the actually measured value. And step S
In step S19, based on the comparison of step S18, step S19
The timer time of 100% duty set in step 5 is reset, and in step S20, the timer time of 50% duty ratio set in step S6 is reset. When the load is slightly small as described above, for example, the time of the 50% duty is set shorter than the initial value without changing the value of the 100% duty. Thereafter, step S31
Move to (FIG. 7). In step S21, X is 6
It is determined whether the time is within the range of 5 to 75 milliseconds. If the time is within the range, the process proceeds to step S31. If the time is out of the range, the process proceeds to step S22.

In step S22, it is determined whether or not X is within the range of 75 to 90 milliseconds. If it is within the range, the process proceeds to step S23, and if it is outside the range, the process proceeds to step S26. In step S23, the "large load table" is compared with the actually measured value. Then, based on the comparison in step S23, in step S24, the timer time of 100% duty set in step S5 is reset, and in step S25, the timer time set in step S6 is set to 50%.
Reset the timer time for the% duty ratio. When the load is slightly large as described above, for example, the value of the 50% duty is made longer than the initial value without changing the value of the 100% duty. Thereafter, the process proceeds to step S31 (FIG. 7).

In step S26, it is determined whether or not X exceeds 90 milliseconds. If not exceeded, the process proceeds to step S30, where error processing is performed, and this flow ends. If it is determined in step S26 that the time exceeds 90 milliseconds, in step S27, the "extra load table" is compared with the actually measured value. Then, based on the comparison in step S27, in step S28, the timer time of 100% duty set in step S5 is reset, and in step S29, the timer time set in step S6 is set to 50%.
Reset the timer time for the% duty ratio. When the load is very large as described above, for example, both the 100% duty time and the 50% duty time are set longer than the initial values. Thereafter, the process proceeds to step S31 (FIG. 7).

In step S31, it is determined whether the time of 100% duty set in step S5 or reset in any of S15, S19, S24 and S28 according to the detection result of the intermediate thread trimming sensor 58 has ended. Is determined. This determination is repeated until the process is completed, and when the process is completed, the process proceeds to step S32. In step S32, the value set in step S6 or S16, S20, S2
5. The timer of 50% duty which is reset in either of S29 and S29 is started, and the drive signal to the presser lifting solenoid 1 is switched to 50% duty. Step S
At step 33, it is determined whether or not the timer set at step S32 has expired, and this determination is repeated until the timer ends, and if completed, at step S34, the presser lifting solenoid 1 is turned off.
Then, a series of flows ends.

According to the sewing machine 100 described above, the driving speed of the solenoid 1 is detected by the intermediate thread trimming sensor 58 every time the thread trimming / lifting device 10 is operated, and the presser is not lifted based on the result. An appropriate driving condition for performing only the thread trimming is selected, and the presser lifting solenoid 1 is controlled and driven according to the selected condition. In other words, since the presser lifting solenoid 1 is driven under the driving condition of performing only the thread trimming obtained based on the actual operation speed, even if there is a difference in the performance of the solenoid 1 due to variations between products and operations. Thus, it is possible to reliably perform only the thread trimming. In addition, new driving means and the like are not provided and expensive components are not used, and only the detecting means is provided, so that the cost hardly increases. Further, since the intermediate thread trimming sensor 58 is provided on the presser lifting link 4 that is interlocked with the presser lifting solenoid 1, the speed can be reliably detected by operating with the presser lifting link 4, and the structure is not complicated. In this respect, the cost can also be reduced in this respect.

The present invention is not limited to the above embodiment, but can be modified as appropriate. For example, a plurality of intermediate thread cut sensors may be provided instead of one in order to further increase the accuracy. The operating speed may be detected not by a photo interrupter but by a distance measuring sensor, or a potentiometer or the like may be installed on a rotating portion such as a fulcrum of a lifting lever to detect an angular speed. Also, the above four data tables used when there is a difference between the standard time and the actual measurement value X with respect to the intermediate thread trimming detection signal are merely examples, and the number of tables, the threshold value for determining which table to use, and the like. It can be changed as appropriate. Instead of using a data table, an arithmetic expression may be stored and an arithmetic operation may be performed according to the difference.
Further, the determination may be made by combining a data table and an arithmetic expression. In addition, in FIGS. 6 and 7, when the time from the ON of the presser lifting solenoid to the detection time of the intermediate thread trimming sensor 58 is different from the standard time, the driving time at 100% duty or 50% duty is changed. Although this has been dealt with, it may be dealt with by changing the duty ratio. Furthermore, it is possible to cope with the increase and decrease of the applied voltage.

[0037]

According to the first aspect of the present invention, based on the operating speed of the driving means detected by the detecting means, the driving means drives the thread cutting means and does not drive the presser lifting means by the driving condition obtaining means. The drive condition in the case is obtained, and the drive unit is controlled by the drive condition acquired by the drive condition acquisition unit under the control of the control unit. Therefore, the driving means
Since the drive is performed under the drive condition of performing only the thread trimming obtained based on the actual operation speed, even if there is a difference in the ability exerted by the drive means due to variations between products or operations,
Only the thread trimming is surely performed. In addition, new driving means and the like are not provided and expensive components are not used, and only the detecting means is provided, so that the cost hardly increases.

According to the second aspect of the present invention, since the detecting means is provided on the member which is interlocked with the driving means when it starts moving, the speed can be reliably detected by operating with the interlocking member. In addition, since it is provided on a member for transmitting the movement of the driving means, even if the detecting means is provided, the structure is not complicated, and the cost can be reduced in this respect as well.

[Brief description of the drawings]

FIG. 1 is a side view showing a part of a sewing machine as an example of the present invention.

FIG. 2 is a block diagram showing a control device of the sewing machine shown in FIG. 1;

FIG. 3 is a perspective view of a thread trimming / holding device provided in the sewing machine of FIG. 1;

FIG. 4 is a graph showing load characteristics of the presser lifting solenoid of FIG. 3;

FIG. 5 is a timing chart of control of the thread trimming / pressing device when only thread trimming is performed.

FIG. 6 is a flowchart showing a presser lifting solenoid control process when only thread trimming is performed.

FIG. 7 is a flowchart showing a continuation of FIG. 6;

FIG. 8 is a timing chart of control of a thread trimming / pressing device when only thread trimming is performed in a conventional sewing machine.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 presser lifting solenoid (driving means) 4 presser lifting link (interlocking member) 4a passing member 7 cloth presser 50 controller 53 CPU (controlling means, driving condition acquiring means) 54 RAM 55 ROM 58 intermediate thread trimming sensor (detecting means) ) 59 sewing machine motor 10 thread trimming and presser lifting device (thread trimming means, presser lifting means) 100 sewing machine

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Claims (2)

[Claims] 1. A thread cutting means for cutting a thread, a presser lifting means for raising a cloth presser for holding a cloth, and a predetermined stroke from an initial state, whereby the thread cutting means is driven, and then the presser foot is raised. A sewing machine having a driving means for driving the means, a detecting means for detecting an operating speed of the driving means, and the driving means driving the thread cutting means based on the operating speed detected by the detecting means; A drive condition acquisition unit that acquires a drive condition when not performed, and a drive condition acquired by the drive condition acquisition unit when only the thread trimming is performed and the operation of the presser lifting unit is unnecessary.
A sewing machine comprising: a control unit that controls a driving unit. 2. The sewing machine according to claim 1, wherein the detecting means is provided on a member interlocked with the operation of the driving means from the initial state to driving of the thread cutting means.