KR20090004680A - Sewing machine - Google Patents

Abstract

A sewing machine is provided to allow the height of the center two triangular pieces under the metal handle of a plow-blade to be set easily. A sewing machine comprises a center two triangular piece motor under the metal handle of a plow-blade; an encoder for detecting the rotation amount of the center two triangular piece motor; a sewing data memory unit; a pulse number detection control unit for detecting the drive pulse number corresponding to the rotation amount of the center two triangular piece motor; a pulse difference calculation unit; a control unit the height of the center two triangular pieces; and a sewing data preset control unit.

Description

Sewing machine {SEWING MACHINE}

The present invention relates to a sewing machine having a central presser foot device.

Conventionally, in the sewing machine which conveys the fabric held by the frame-shaped fabric holding member in the XY direction while forming embroidery or needle stitches of a predetermined shape, the holding force by the fabric holding member is weak when sewing the vicinity of the frame center of the fabric holding member. The friction with the needle sometimes caused the fabric to flutter together with the needle, thus affecting sewing.

For this reason, in such a sewing machine, as disclosed, for example, in Patent Document 1, a central presser foot device is provided which presses down the periphery of the needle penetrating portion of the fabric when the needle is raised. The center presser foot device is typically pressed down by the center presser foot when the needle is lifted from the fabric, and the center presser foot is raised with the needle after the needle has completely risen from the fabric.

And so that the center presser foot device preferably prevents flapping of the fabric, the thickness of the fabric, the end of the fabric, etc., for each needle drop point at which the needle sticks the fabric during sewing in response to a predetermined sewing pattern. Therefore, the height of the center presser foot is adjusted beforehand.

[Patent Document 1] Japanese Patent Laid-Open No. 2006-102376

However, in the case of the prior art, for example, by pressing a variety of operation buttons in the touch panel operation panel provided in the sewing machine to switch to various display screens to set the height of the center presser foot for each needle drop point At the same time, there is a complicated task of visually confirming whether the height of the center presser foot according to the set value is appropriate, and there is a problem that such a task is a burden on the user.

An object of the present invention is to provide a sewing machine that can easily set the height of the center presser foot.

In order to solve the above problems, the invention described in claim 1, the holding frame for horizontally moving on the needle plate while holding the to-be-sealed material on the needle plate, a sewing needle moving up and down with respect to the material to be held by the holding frame; A sewing machine comprising a central presser foot for pressing the sewing object toward the needle plate during sewing.

A center presser foot motor 4 for moving the center presser foot up and down to interlock with the shanghai east of the sewing needle;

An encoder 5 for detecting the rotation amount of the central presser foot motor,

Sewing data storage means (203) for storing in advance sewing data consisting of a plurality of needle drop point data;

When the center presser foot motor is driven based on the number of reference pulses for moving the center presser foot by a reference amount, the center presser foot detected by the encoder for each needle drop point according to the sewing data in a predetermined sewing object. Pulse number detection control means (201, S104) for detecting the number of drive pulses corresponding to the rotational amount of the motor;

Pulse difference calculating means (201, S105) for calculating a difference between the number of driving pulses detected by said pulse detecting means and the number of reference pulses driving said central presser foot motor;

Center presser foot height setting control means (201, S106) for setting the height of the center presser foot for each needle drop point based on the difference in the number of pulses calculated by the pulse difference calculating means;

And a sewing data setting control means 201, S110 for storing the height of the center presser foot set by the center presser foot height setting control means in correspondence with each needle drop point.

According to the invention as set forth in claim 1, the sewing machine moves to the sewing object held in the holding frame in accordance with the sewing data stored in the sewing data storage means, and the sewing machine corresponds to the portion of the sewing object corresponding to each needle drop point in the sewing data. When driving the center presser foot motor to face the center presser foot, the drive pulse corresponding to the reference pulse number input to drive the center presser foot motor and the actual rotation amount of the center presser foot motor detected by the encoder at each needle drop point By calculating the difference between the numbers, the height of the center presser foot abutting the to-be-sealed material can be set to the height of the centered foot according to the thickness and the end of the to-be-sealed material for each needle drop point. Sewing data reflecting the center presser foot height set for each needle drop point can be created.

The invention according to claim 2 is the sewing machine according to claim 1,

Thread tension adjusting mechanism 30 for imparting thread tension to the sewing machine thread supplied to the sewing needle,

Thread tension storage means 203 for storing yarn tension data for each height of the center presser foot in advance;

The sewing data setting control means associates the thread tension corresponding to the height of the center presser foot set by the center presser foot height setting control means with each needle drop point based on the thread tension data stored in the thread tension storage means. It is characterized by remembering.

According to the invention as set forth in claim 2, the sewing machine performs the same action as the invention as set forth in claim 1, and the thread is stored in the thread tension storage means with a thread tension corresponding to the center presser foot height set by the center presser foot height setting control means. Based on the tension data, it can be stored in correspondence with each needle drop point and reflected in the sewing data.

According to the invention as set forth in claim 1, the sewing machine moves to the sewing object held in the holding frame in accordance with the sewing data stored in the sewing data storage means, and the sewing machine corresponds to the portion of the sewing object corresponding to each needle drop point in the sewing data. When driving the center presser foot motor to face the center presser foot, the drive pulse corresponding to the reference pulse number input to drive the center presser foot motor and the actual rotation amount of the center presser foot motor detected by the encoder at each needle drop point By calculating the difference between the numbers, based on the calculated difference in the number of pulses, the height of the center presser foot is in contact with the to-be-sealed object, and the thickness or end portion of the to-be-sealed object for each needle drop point is The height of the center presser foot can be set, and sewing data reflecting the height of the center presser foot for each set needle drop point You can write

That is, as in the prior art, without operating the operation panel to set and input the center presser foot height for each needle drop point, or to perform visually checking whether the actual center presser foot height is appropriate according to the set value, In this sewing machine, the height of the center presser foot for each needle drop point can be set almost automatically, and the burden on the operator can be greatly reduced.

Thus, the sewing machine may be referred to as a sewing machine that can easily set the height of the center presser foot.

According to the invention as set forth in claim 2, the sewing machine makes the thread tension corresponding to the center presser foot height set by the center presser foot height setting control means correspond to each needle drop point based on the thread tension data stored in the thread tension storage means. Since the height of the center presser foot can be stored and reflected in the sewing data, an appropriate thread tension corresponding to the height of the center presser foot is reflected in the sewing data, and more suitable sewing data can be created.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, embodiment of the sewing machine which concerns on this invention is described in detail.

In this embodiment, the electronic cycle sewing machine will be described as an example of the sewing machine.

The electronic cycle sewing machine has a holding frame for holding the cloth, which is the sewing object to be sewn, and the holding frame is moved relative to the sewing needle, so that the stitches based on predetermined sewing data (sewing pattern) are applied to the cloth held in the holding frame. It is a sewing machine to form.

Here, the direction in which the sewing needle 108 to be described later moves up and down is referred to as the Z axis direction (up and down direction), and one direction orthogonal to this is set as the X axis direction (left and right direction), and the Z axis direction and the X axis direction The direction orthogonal to both directions is set as the Y-axis direction (front and rear direction).

Electronic cycle sewing machine 100 (hereinafter referred to as "sewing machine 100"), as shown in Figure 1, the sewing machine main body 101 is provided on the upper surface of the sewing machine table (T), the lower portion of the sewing machine table (T) And a pedal R for operating the sewing machine main body 101 or an operation panel 300 provided at an upper portion of the sewing machine table T to perform an input operation by a user.

(The sewing machine body)

1 and 2, the sewing machine frame 102 constituting the sewing machine main body 101 forms an upper portion of the sewing main body 101 and extends in the front-rear direction to the sewing machine arm portion 102a and the sewing main body ( And a sewing machine bed portion 102b extending in the front and rear direction and a vertical body portion 102c connecting the sewing machine arm portion 102a and the sewing machine bed portion 102b.

The main shaft (not shown) disposed in the sewing machine arm portion 102a is provided with a rotational force by the main shaft motor 20 (see FIG. 4). In addition, the lower shaft (not shown) disposed inside the sewing machine bed portion 102b is connected to rotate in conjunction with the main shaft.

The needle bar 108a having the sewing needle 108 fixed to the lower end thereof is supported by the sewing machine arm portion 102a so as to move up and down as the main shaft rotates.

The sewing machine arm 102a such that the central presser foot device 1 (see FIG. 3) having the central presser foot 2 for pressing the fabric around the sewing needle 108 downwardly can move up and down in association with the shank east of the needle bar 108a. ) Is installed. The center presser foot 2 is formed with a through hole through which the sewing needle 108 passes.

The sewing machine arm 102a is provided with a thread tension adjusting mechanism 30 (see Fig. 4) having a well-known structure for imparting thread tension to the sewing machine thread supplied to the sewing needle 108.

The attachment member 113 arranged to move horizontally on the sewing machine bed 102b is connected to an X-axis motor (not shown) and a Y-axis motor (not shown) disposed inside the sewing machine bed 102b. The holding frame 111 in the shape of a frame is detachably supported at the tip of the attachment member 113 so as to face the shanghai path of the sewing needle 108, and is attached to the front and rear, left and right directions together with the attachment member 113. Go to.

In addition, the attachment member 113 is rotatably provided so as to move the holding frame 111 at the front end by driving the cloth pressing motor (not shown) disposed in the sewing machine arm 102a. In the member 113, a lower plate (not shown) parallel to the needle plate is provided below the holding frame 111, and the fabric is pinched and held between the lower plate and the lower plate when the holding frame 111 is lowered.

In addition, the technique of forming needle stitches based on sewing data composed of a plurality of needle drop point data by the cooperation of the holding frame 111 moving forward, backward, left and right, and the sewing needle 108 moving up and down is not known. As it is the same, it is not described in detail here.

The pedal R as the operation pedal is fitted with a sensor for detecting the depression operation position at which the pedal R is pressed, and the output signal from the sensor is referred to the control device 200 described later as the operation signal of the pedal R. It is output and configured to drive and operate the sewing machine 100 in accordance with the operation position or the operation signal.

In addition, an operation panel 300 is provided on the sewing machine table T to perform an operation input by a user, and various data and operation signals inputted to the operation panel 300 are controlled by the control device 200 described later. Is output.

In addition, the operation panel 300 includes a liquid crystal display panel and a touch panel provided on the display screen of the liquid crystal display panel, and the touch panel is touched by touching the various operation keys displayed on the liquid crystal display panel. The instructed position is detected, and an operation signal corresponding to the detected position is output to the control device 200 described later.

(Center presser foot device)

As shown in Fig. 3, the center presser foot device 1 includes a center presser foot 2 for pressing the fabric toward the needle plate 110 at the time of sewing, a center presser foot 2 at the lower end thereof, and a rack 3a on the side thereof. The center presser foot stand 3 formed, the center presser foot motor 4 provided with the pinion 4a, the encoder 5 etc. which detect the rotation amount of the center presser foot motor 4, etc. are provided. In addition, the center presser foot stand 3 is supported by a pair of upper and lower bearings 6 and 6 so as to be movable.

The center presser foot 2 is a distal end portion of the center presser foot device 1 which abuts the fabric around the sewing needle 108 downward, and has a through hole through which the sewing needle 108 passes.

The center presser foot stand 3 is supported by the bearings 6 and 6 so as to be movable, and the rack 3a formed on the side surface is engaged with the pinion 4a of the center presser foot motor 4.

The center presser foot motor 4 is a pulse motor, which rotates the pinion 4a forward and reverse according to the input of the pulse signal. The center presser foot motor 4 reversely rotates the pinion 4a at a rotational amount corresponding to the number of pulses in the pulse signal, and the center presser foot 3 and the rack 3a engaged with the pinion 4a. The central presser foot (2) is moved to Shanghai. That is, according to the rotation amount which the center presser foot motor 4 rotates the pinion 4a, the movement amount which the center presser foot 2 moves up and down is adjusted.

The encoder 5 detects the amount of rotation of the center presser foot motor 4, in particular, the amount of positive rotation in the positive direction and the amount of negative rotation in the reverse direction, and outputs it to the controller 200 described later.

(Control device)

Next, the control device 200 of the sewing machine will be described.

As shown in FIG. 4, the control device 200 includes a CPU 201 that executes various controls and processes in accordance with a program for controlling the operation of each part of the sewing machine 100, a program for setting processing of sewing data, and the like; RAM 202 serving as a work area of the CPU 201, a ROM 203, an EEPROM 204, and the like for storing a program or process data for executing various processes are provided.

In the ROM 203, basic sewing data indicating a sewing pattern composed of a plurality of needle drop point data is stored, and functions as sewing data storage means.

The ROM 203 also stores a table relating to thread tension data for each center presser foot height, to which the center presser foot height and the thread tension are associated, and function as a thread tension storage means.

The ROM 203 stores a center presser foot height setting program for setting the center presser foot height for the basic sewing data, that is, the center presser foot height for each needle drop point in the basic sewing data.

Then, the CPU 201 executes the center presser foot height setting program, so that the CPU 201 uses the center presser foot motor based on the reference pulse number for moving the center presser foot 2 by the reference amount for each needle drop point according to the sewing data. The center presser foot motor detected by the encoder 5 at each needle drop point when the center presser foot 2 abuts against each needle drop point in the predetermined object to be driven; It functions as pulse number detection control means for detecting the number of drive pulses corresponding to the rotation amount of 4). In addition, the number of driving pulses detected when the central presser foot 2 is moved by a reference amount without contacting the object to be processed is equal to the number of reference pulses.

In addition, by the CPU 201 executing the center presser foot height setting program, the CPU 201 is used to drive the number of drive pulses detected by the CPU 201 as the pulse number detection control means and the center presser foot motor 4. It serves as a pulse difference calculating means for calculating a difference of the input reference pulse number.

In addition, when the CPU 201 executes the center presser foot height setting program, the CPU 201 causes the center presser foot for each needle drop point based on the difference in the number of pulses calculated by the CPU 201 as the pulse difference calculation means. It functions as a center presser foot height setting control means for setting the height of (2). The CPU 201 as the center presser foot height setting control means is, for example, a table previously stored in the ROM 203, and is based on data in the center presser foot height table to which the difference in the number of pulses and the center presser foot height are associated. The center presser foot height is set.

As the CPU 201 executes the center presser foot height setting program, the CPU 201 stores the center presser foot height set by the CPU 201 as the center presser foot height setting control means in correspondence with each needle drop point. It functions as sewing data setting control means to be reflected in sewing data. That is, the CPU 201 as sewing data setting control means sets new sewing data to which data relating to the center presser foot height is given for each needle drop point in the basic sewing data, and the new setting sewing data is sent to the EEPROM 204. Perform the control to memorize.

Further, the CPU 201 as the sewing data setting control means has a thread tension corresponding to the height of the center presser foot set by the CPU 201 as the center presser foot height setting control means for each center presser foot height stored in the ROM 203. Based on the actual tension data, the control is executed in correspondence with each needle drop point and reflected in the sewing data. That is, the CPU 201 as sewing data setting control means sets new sewing data to which data relating to the center presser foot height and thread tension is set for each needle drop point in the basic sewing data, and the new setting sewing data is stored in EEPROM ( The control stored in 204 is executed.

(Setting process of center presser foot height)

Next, a process of setting the height of the center presser foot 2 of the center presser foot device 1 in accordance with the sewing data in the sewing machine 100 according to the present invention will be described based on the flowchart shown in FIG. 5. .

First, the user sets the cloth (cloth) which is the object to be sewn on the holding frame 111 of the sewing machine 100 (step S101). The basic sewing data relating to the sewing pattern applied to the fabric is selected by the user in a predetermined procedure.

Subsequently, the user turns on the predetermined center presser foot height setting start switch (starting SW; not shown) in the operation panel 300 of the sewing machine 100, so that the holding frame 111 is a process according to the selected sewing data. The center presser foot height setting process for the fabric set in step (2) is started (step S102).

Then, as the start SW is turned on, the CPU 201 outputs a pulse signal of the reference pulse number to the center presser foot motor 4 of the center presser foot device 1, and the center presser foot motor 4 inputs the reference pulse. On the basis of the number (pulse signal), the center presser foot 2 is driven to move by a reference amount, and the center presser foot 2 is directed toward the cloth held by the holding frame 111 on the needle plate 110 side. It descends toward the needle fall point (the needle fall point according to the sewing data which shows a predetermined sewing pattern) in the cloth (step S103). In this embodiment, a pulse signal of the reference pulse number " + 10 "

Subsequently, the CPU 201 detects the amount of rotation of the central presser foot motor 4 when the central presser foot 2 descends toward the needle drop point on the cloth, by the encoder 5, and for each needle drop point. The number of driving pulses corresponding to the rotation amount of the center presser foot motor 4 detected by the encoder 5 is detected (step S104).

Subsequently, the CPU 201 calculates a difference (difference = number of reference pulses-number of driving pulses) between the detected number of driving pulses and the number of reference pulses input for driving the center presser foot motor 4 (step S105). .

Next, the CPU 201 sets the height of the center presser foot 2 for each needle falling point based on the calculated difference in the number of pulses (step S106). Specifically, the CPU 201 is a table stored in advance in the ROM 203 based on the calculated difference in the number of pulses. The CPU 201 is a table stored in advance in the data in the center presser foot height table to which the difference in the number of pulses and the center presser foot height are associated. Set the center presser foot height based on that.

Here, the process in which the center presser foot height is set as the center presser foot 2 descends toward the cloth will be described in detail with reference to FIGS. 6 and 7.

The cloth set in the holding frame 111 is two pieces of cloth superimposed on cloth as shown in FIG. 6, and the fabric is passed through the needle drop point B and the needle drop point C from the first needle drop point A, and the last needle. In the case of the setting processing relating to the sewing pattern to sew to the falling point D, the CPU 201 at each needle drop point from the needle drop point A of the first needle stitch to the needle drop point B of the tenth needle stitch If the detected drive pulse number is "+10", the pulse number difference is calculated to be "0" based on the center presser foot height table shown in FIG. 7, and the center presser foot height is set to "0mm". That is, from the needle drop point A of the first needle stitch to the needle drop point B of the tenth needle stitch, the center presser foot motor 4 is driven down based on the pulse signal of the reference pulse number " + 10 " It can be said that the center presser foot 2 does not touch the fabric and falls to the lowest point.

In addition, in each needle drop point from the needle drop point of the eleventh needle stitch to the needle drop point C of the twentieth needle stitch, if the number of driving pulses detected by the CPU 201 is " + 8 " Based on the same center presser foot height table, the pulse aberration difference is calculated to be "2", and the center presser foot height is set to "2mm". That is, from the needle drop point of the eleventh needle stitch to the needle drop point C of the twentieth needle stitch, the center presser foot which is lowered as the center presser foot motor 4 is driven based on the pulse signal of the reference pulse number " + 10 " 2) is a region in contact with the fabric at a position corresponding to the number of driving pulses " + 8 ". And the 11th needle stitch is detected as having the edge part of the cloth.

Moreover, in each needle drop point from the needle drop point of the 21st needle stitch to the needle drop point D of the 30th needle stitch, if the number of driving pulses detected by the CPU 201 is "+10", the center shown in FIG. Based on the presser foot height table, the pulse aberration difference is calculated to be "0", and the center presser foot height is set to "0mm". That is, from the needle drop point D of the twenty-first needle stitch to the needle drop point D of the thirtieth needle stitch, the center presser foot lowered as the center presser foot motor 4 is driven based on the pulse signal of the reference pulse number "+10" ( 2) It can be said to be an area falling to the lowest point without touching the fabric. Then, the 21st needle stitch is detected as having an end portion of the fabric.

The CPU 201 outputs to the center presser foot motor 4 the pulse signal of the number of drive pulses having the same magnitude as the number of drive pulses detected in step S104 and having a different value of plus or minus, and raises the center presser foot 2. The origin is detected (step S107). Specifically, each needle drop point from the needle drop point (A) of the first needle stitch to the needle drop point (B) of the tenth needle stitch, and the needle drop point (D) of the thirtieth needle stitch from the needle drop point of the 21st needle stitch (D). At each needle drop point up to), the center presser foot motor 4 is driven based on the pulse signal of the driving pulse number "-10", and the center presser foot 2 rises to the origin. Further, at each needle drop point from the needle drop point of the eleventh needle stitch to the needle drop point C of the twentieth needle stitch, the center presser foot motor 4 is driven based on the pulse signal of the driving pulse number "-8". The center presser foot 2 rises to the origin.

Subsequently, the CPU 201 determines whether the final needle drop point (the needle drop point D of the thirtieth needle stitch) has been reached (step S108).

If the CPU 201 determines that the final needle drop point has not been reached (step S108; No), the holding frame 111 moves to switch to the arrangement corresponding to the next needle drop point (step S109). The flow returns to step S103.

On the other hand, if the CPU 201 determines that the final needle drop point has been reached (step S108; Yes), the CPU 201 sets the height of the center presser foot for each needle drop point set so far from the basic sewing data. Corresponding to each needle drop point of the, new sewing data provided with data relating to the center presser foot height is set for each needle drop point in the basic sewing data, and the new set sewing data is stored in the EEPROM 204. In particular, the CPU 201 drops each needle of the sewing data based on the thread tension data (for example, the table in FIG. 7) for each center presser foot height stored in the ROM 203 with the thread tension corresponding to the set center presser foot height. Corresponding to the point, the new sewing data in which data relating to the center presser foot height and the thread tension is given to each needle drop point in the basic sewing data is stored in the EEPROM 204 (step S110).

Then, the center presser foot height setting process is finished.

When the same sewing pattern is sewn on the same fabric by using sewing data provided with data relating to the center presser foot height and the thread tension for each needle dropping point, as the new sewing data stored in the EEPROM 204, the center presser foot (2) is arrange | positioned at an appropriate height, and it becomes possible to suitably perform the sewing adjusted to the appropriate thread tension.

In this way, the sewing machine 100 moves the cloth held on the holding frame 111 according to the sewing data having a desired sewing pattern, while the center presser foot ( 2) By driving the center presser foot motor 4 of the center presser foot device 1 to face each other, it is possible to suitably set the height of the center presser foot 2 according to the thickness and the end of the cloth at each needle drop point. Sewing data reflecting the center presser foot height set for each needle drop point and the thread tension corresponding to the center presser foot height can be created, and the new sewing data can be stored in the EEPROM 204.

That is, as in the prior art, without operating the operation panel to set and input the center presser foot height for each needle drop point, or to check visually whether the actual center presser foot height is appropriate according to the set value, The sewing machine 100 can set the height of the center presser foot almost automatically for each needle drop point, thereby greatly reducing the burden on the user.

Therefore, the sewing machine 100 may be referred to as a sewing machine that can easily set the height of the center presser foot (2).

When the same sewing pattern is sewn on the same fabric by using sewing data provided with data relating to the center presser foot height and the thread tension for each needle dropping point, as the new sewing data stored in the EEPROM 204, the center presser foot (2) can be suitably given to the sewing which was arrange | positioned at the appropriate height and adjusted to the appropriate thread tension.

In addition, in the above embodiment, although the setting process of the center presser foot height regarding sewing of the linear sewing pattern was demonstrated to the cloth which two pieces of cloth were superimposed for example, this invention is not limited to this, Any cloth, arbitrary The setting process regarding the sewing pattern may be sufficient.

In addition, of course, the specific detailed structure and the like can also be changed as appropriate.

1 is a perspective view showing a sewing machine according to the present invention.

Fig. 2 is an enlarged perspective view showing the vicinity of the holding frame of the sewing machine and the center presser foot.

3 is a perspective view showing a central presser foot device.

4 is a block diagram showing a control device of the sewing machine according to the present invention.

Fig. 5 is a flowchart showing the center presser foot height setting process in the sewing machine according to the present invention.

6 is an explanatory diagram showing a cloth and a sewing pattern applied to the cloth.

7 is an explanatory diagram showing a table of data relating to the height of the center presser foot.

           Explanation of symbols on the main parts of the drawings

1: center presser foot device

2: center presser foot

3: center presser foot

3a: rack

4: center presser foot motor

4a: pinion

5: encoder

20: spindle motor

30: thread tension adjusting mechanism

100: sewing machine

108: sewing needle

110: needle plate

111: retention frame

200: control device

201: CPU (pulse number detection control means, pulse difference calculation means, center presser foot height setting control means, sewing data setting control means)

202: RAM

203: ROM (sewing data storage means, thread tension storage means)

204: EEPROM

300: operation panel

Claims (2)

A holding frame for horizontally moving the needle plate while keeping the object on the needle plate, a sewing needle moving up and down with respect to the object to be held by the holding frame, and a presser foot for pressing the object to the needle plate during sewing. As a sewing machine provided with, A center presser foot motor for moving the center presser foot up and down to interlock with a shanghai east of the sewing needle; An encoder for detecting the rotation amount of the central presser foot motor; Sewing data storage means for storing in advance sewing data consisting of a plurality of needle drop point data, When the center presser foot motor is driven based on the number of reference pulses for moving the center presser foot by a reference amount, the center presser foot detected by the encoder for each needle drop point according to the sewing data in a predetermined sewing object. Pulse number detection control means for detecting the number of drive pulses corresponding to the rotational amount of the motor; Pulse difference calculating means for calculating a difference between the number of driving pulses detected by said pulse detecting means and the number of reference pulses driving said central presser foot motor; Center presser foot height setting control means for setting the height of the center presser foot for each needle drop point based on the difference in the number of pulses calculated by the pulse difference calculating means; And sewing data setting control means for storing the center presser foot height set by said center presser foot height setting control means in correspondence with each needle drop point. The method of claim 1, A thread tension adjusting mechanism for imparting thread tension to the sewing machine thread supplied to the sewing needle; Thread tension storage means for storing yarn tension data for each height of the center presser foot in advance; And said sewing data setting control means stores the thread tension corresponding to the height of the center presser foot set by said center presser foot height setting control means in correspondence with each needle drop point.

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