JP2000233092A - Sewing machine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewing machine control box capable of coping with a plurality of power source specifications and improving the operatability in the switching of power sources. SOLUTION: A sewing machine controller comprises the rectifying and smoothening parts 8C, 9C inputting the external power source and rectifying and smoothening the same, a motor driver 11 for driving a sewing machine motor by the DC power source rectified and smoothened by the rectifying and smoothening parts 8C, 9C, a power source transformer 24 inputting the external AC power source and converting the voltage, and an actuator driver for driving a sewing machine K actuator by the AC power source of which the voltage is converted by the power source transformer 24. The rectifying and smoothening parts 8C, 9C have a full-wave rectifying means and a voltage doubler rectifying means, the power source transformer 24 has at least two independent windings n1, n2, and further a switching means 23 is mounted for simultaneously switching the full-wave rectifying means and the voltage doubler rectifying means in the rectifying and smoothening parts 8C, 9C, and switching the windings in the power source transformer 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifying / smoothing unit for rectifying / smoothing an external AC power supply, a power supply transformer for converting a voltage of an external AC power supply, a motor driving driver for driving a sewing machine motor, and an actuator provided for the sewing machine. The present invention relates to a control device of a sewing machine having an actuator driver.

[0002]

FIG. 8 is a perspective view showing a configuration example of a conventional industrial sewing machine. In the figure, 1 is a sewing machine main body, 2 is a sewing machine motor, 3 is a control box as a control device, 4 is a power switch, 5 is a pedal, and 6 is an operation box. Recent industrial sewing machines are equipped with a plurality of actuators (solenoids, air cylinders, etc.) on the sewing machine body 1 to automate operations of a thread cutting device, a reverse stitching mechanism, and the like. The sewing machine motor 2 generally uses an inverter motor, a servo motor, or the like for performing position control or speed control. The control box 3 has a circuit for supplying power to the sewing machine motor from a commercial power supply and a circuit for driving the actuator, and is configured by a microcomputer or the like for controlling these circuits. The power switch 4 connects / disconnects the commercial power to / from the control box 3. The pedal 5 is used by a sewing operator (hereinafter referred to as an operator) to control the sewing machine. The sensor attached to the control box 3 converts the movement of the pedal into an electric signal.
Controls the sewing machine motor 2 and the actuator. The operation panel 6 is used by an operator to set various sewing patterns and the like. The information is sent to the control box 3 to realize a sewing operation instructed by the operator.

FIG. 9 is a block diagram showing one configuration example of a conventional control box 3. As shown in FIG. The commercial power supply is filtered from the power switch 4 by the filter unit 7 to remove noise, and is converted to a DC voltage by the rectifying unit 8 and the smoothing unit 9. The inrush current limiting circuit 10 is a circuit for preventing an excessive current flowing when the power is turned on. There may be various circuits, but a parallel circuit of a relay contact and a resistor is generally used. The DC power is supplied to the sewing machine motor 2 by the motor driver 11. Further, the DC-DC converter 12 performs voltage conversion, and supplies control power (+5 V, +12 V, etc.) to the CPU 13 and its peripheral circuits. The CPU 13 receives an encoder signal from the encoder 14 built in the sewing machine motor 2 by the microcomputer, and issues a motor control command to the motor control means 15. The motor control unit 15 sends a motor excitation timing command to the motor driver 11 to rotate the sewing machine motor 2.

A power transformer 16 is used to drive a commercial power supply to a driving voltage for an actuator (generally, about 20 to 30 V AC).
, And outputs this from the actuator power supply circuit 17 to the actuator driver 18. The actuator driver 18 drives a plurality of actuators such as a thread cutter 19, a reverse stitch 20, and a presser foot 21 built in the sewing machine by the power supply. The CPU 13 controls the pedal 5,
The operator receives a plurality of input signals from the operation panel 6, the needle bar position sensor 22, etc., controls the speed and the stop position of the sewing machine motor 2 at an optimal timing, and optimizes the drive timing of the actuator, thereby enabling the operator The instructed sewing operation is realized.

[0005] Generally, a commercial power supply is an AC 100V system and an AC power supply.
The rectifier 8 and the smoothing unit 9 convert a commercial power supply into a DC voltage of a predetermined voltage (input AC voltage × 2 ^1/2 ), which is supplied to the motor driver 11 to drive the sewing machine motor 2. However, at the time of input of AC 100 V and at the time of input of AC 200 V, the DC voltage is about twice different, and the output torque of the sewing machine motor changes greatly accordingly.

For this reason, normally two types of sewing machine motors 2 must be prepared for the AC 100 V system input and the AC 200 V system input, and in this case, there is a problem that the motor replacement work is not easy. Alternatively, it is common to divide the control box 3 depending on circumstances, such as not wanting to increase the types of motors. FIG.
3 shows a configuration example of a rectifying unit 8 and a smoothing unit 9 of a control box 3 for V-system input. The commercial power supply is supplied with a DC voltage A by a voltage doubler circuit composed of a rectifying unit 8A and a smoothing unit 9A.
(= Input AC voltage × 2 × 2 ^1/2 ) and supplied to the motor driver 11. The inrush current limiting circuit 10 limits an excessive current when the power is turned on with a resistor, and turns on the relay after a predetermined time.

FIG. 11 shows an example of the configuration of the rectifying unit 8 and the smoothing unit 9 of the control box 3 for AC 200 V system input. The commercial power is converted into a DC voltage B (= input AC voltage × 2 ^1/2 ) by a full-wave rectifier circuit including a rectifier 8B and a smoother 9B, and supplied to the motor driver 11. The AC 200 V system input may be a three-phase power supply, and if the inrush current limiting circuit 10 is arranged in front of the rectifying unit 8 B as in the case of AC 100 V input, it is necessary to arrange two inrush current limiting circuits. It is common to arrange between 9B. If two types of control boxes for an AC 100 V system input and a control box for an AC 200 V system are prepared and used properly for the input voltage of a commercial power supply, the DC voltage A shown in FIG. 10 and the DC voltage A shown in FIG. DC voltage B is almost the same voltage, so that the common sewing machine motor 2
Can be controlled. The power supply transformer 16 shown in FIG. 9 also uses the same voltage to be supplied to the actuator power supply circuit 17,
It is common to use different ones for each one. As described above, the rectifying method and the power transformer 16 are used.
Control box 3 according to the commercial power supply voltage specification
Are prepared and supported.

[0008]

However, since the control box 3 of the conventional sewing machine has a different control box depending on the commercial power supply specifications of the user, for example, the power supply associated with the relocation of the factory or the movement of the sewing machine at the user's site. When the specification changed, there was a problem that the replacement work of the control box was required. In addition, the side that sells the sewing machine also needs to have a plurality of stocks according to the power supply specification, and there has been a problem in that the labor for management is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a control box for a sewing machine which can cope with a plurality of power supply specifications and can perform the switching operation with good operability. I do.

[0010]

In order to solve the above-mentioned problems, the present invention is directed to a rectifying / smoothing section for rectifying and smoothing by inputting an external AC power supply, and a DC power supply rectified and smoothed by the rectifying / smoothing section. , A motor drive driver for driving the sewing machine motor, a power transformer for inputting the external AC power to convert the voltage, and driving one or more actuators provided in the sewing machine with the AC power converted by the power transformer. A rectifying / smoothing unit having a full-wave rectifier and a voltage doubler rectifier, and the power transformer having two or more independent windings on a primary side. Further, switching between the full-wave rectifier and the voltage doubler rectifier in the rectifying / smoothing unit and switching of the winding in the power transformer at the same time. And configured to include a means.

According to the first aspect of the present invention, the switching means switches the rectifying method of the rectifying / smoothing section and the winding of the power transformer at the same time, so that one control device and one sewing machine motor are provided. While a plurality of external AC power supplies (for example, AC100V system and AC200
(V-system commercial power supply). The main configuration required for this switching is a rectifying / smoothing unit having two components, a full-wave rectifier and a voltage doubler rectifier, and an independent rectifier / smoothing unit.
Since only the power transformer having one or more windings is used, it can be constructed relatively inexpensively and with a small space.

Here, the above-mentioned switching of the winding means various methods such as a method of switching the number of windings acting on the power transformer and a method of switching the connection of the windings so that the voltage applied between the windings changes. Can be in the form

According to a second aspect of the present invention, in the control device for a sewing machine according to the first aspect, the switching means comprises a connector for switching the rectifying unit and the power transformer in a batch by replacement.

According to the second aspect of the present invention, a plurality of external AC power supplies are switched by replacing the connector, so that reliable and appropriate switching can be performed. That is, the opportunity to change the external AC power source is limited only when the factory is relocated or when electric power work is performed, and the switching is actually performed by the switching means only when the above-mentioned factory relocation or electric power work is performed. There is only a case such as when the external AC power supply is changed or when the sewing machine is shipped, switching is performed in accordance with the power source of the shipping destination. Therefore, it is conceivable that the type that is easily and frequently switched may be accidentally switched, but on the other hand, the replacement of the connector requires a certain amount of work and does not accidentally switch. Is appropriate.

According to a third aspect of the present invention, in the control apparatus for a sewing machine according to the second aspect, the connector doubles as a connector for connecting a primary-side wiring of the power transformer to the external AC power supply. The configuration was adopted.

A conventional sewing machine control device generally has a structure in which a wiring on a primary side of a transformer for generating a power supply for an actuator of the sewing machine and a wiring for leading an external power supply are connected by a connector. According to the third aspect of the present invention, since the switching connector is provided at the same position as the conventional connector and also has the same function as the conventional connector, the presence or position of the connector is determined by the user or the control device. It is easy for the manufacturer to understand, and mistakes such as forgetting to insert a connector can be reduced.

According to a fourth aspect of the present invention, in the sewing machine control device according to the second or third aspect, the rectifying / smoothing unit includes:
When the connector is disconnected, the full-wave rectifier functions while the voltage doubler rectifier does not function.

According to the fourth aspect of the present invention, when an external AC power supply is input in a state where the connector is accidentally disconnected, the full-wave rectifier operates on the AC power supply. The rectified power supply voltage is kept low. Therefore, damage to other devices can be prevented. That is, when an AC power supply with a high power supply voltage is connected with the connector disconnected, the rectified voltage becomes significantly higher than the reference voltage when the voltage doubler rectifier operates, whereas the connector is If the full-wave rectifier operates in the off state, the rectified voltage can be suppressed to a reference voltage or less at both a high power supply voltage and a low power supply voltage.

According to a fifth aspect of the present invention, in the control apparatus for a sewing machine according to the first aspect, the switching means comprises a switch for switching the rectifying / smoothing section and the power transformer in a lump. did.

According to the fifth aspect of the present invention, the change of the external AC power supply can be easily switched with good workability by the switch. Here, the switch includes various switches such as a switch that can be manually switched, a relay contact switch and a power transistor that can be switched by electric control.

According to a sixth aspect of the present invention, in the control apparatus for a sewing machine according to any one of the first to fifth aspects, an inrush current for preventing an inrush current is provided on both the positive and negative sides between the rectifying section and the smoothing section of the rectifying / smoothing section. The configuration is such that a limiting means is provided.

According to the present invention, the inrush current can be prevented by any of the two inrush current limiting means in any of the full-wave rectification means and the voltage doubler rectification means. It is possible to prevent the equipment from being damaged due to the rush current, and to avoid inconveniences such as temporarily consuming excessive electric power, causing an external power supply to become abnormal (such as a breaker being dropped), and the sewing machine cannot be operated. Therefore, it is possible to reduce the cost and size of the circuit.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG.
1 is a block diagram illustrating a configuration of a control box 3 as a sewing machine control device according to an embodiment of the present invention. In addition,
The same components as those in the related art are denoted by the same reference numerals and description thereof is omitted. The commercial power is connected by the power switch 4 and supplied to the control box 3, after which noise is removed by the filter unit 7, and is converted to DC power by the rectifying unit 8 </ b> C and the smoothing unit 9 </ b> C. The DC power is supplied to the motor driver 11 and transmits power to the sewing machine motor 2.

A switching circuit 23 as switching means is connected to the rectifying unit 8C and the smoothing unit 9C constituting the rectifying / smoothing unit, thereby enabling switching of the rectifying method. Two inrush current limiting circuits 10a and 10b are connected between the rectifying unit 8C and the smoothing unit 9C to limit excessive current (rush current) at power-on even in different rectification methods of full-wave rectification and voltage doubler rectification. To join. The power transformer 24 has a primary-side winding which is divided into a plurality of parts independently.
By switching the mode of the winding divided into a plurality of parts, the output voltage on the secondary side supplied to the actuator power supply circuit 17 through the connector 34 is kept constant in both cases of inputting AC 100 V and inputting AC 200 V. It has become possible. Next, the details will be described.

FIG. 2 is a wiring diagram showing details of the switching circuit 23. The switching circuit 23 includes connectors 25, 26, 2
7. The connectors 25 and 26 have the same pin shape, and each pin, the rectifying unit 8C and the smoothing unit 9C
The wiring is connected by a copper foil pattern on the substrate as shown in FIG. The connector 27 is configured to be connected to one of the connectors 25 and 26. As shown in FIG. 2, each pin is connected to a primary winding n1, n2 of the power transformer 14.
, And the short pin 28. The power transformer 24 has its primary side divided into two independent windings n1 and n2. Two divided windings n
The number of turns of 1, n2 is the same. Commercial power supply is AC100V
In this case, the connector 27 is connected to the connector 25, and when the commercial power is 200 V AC, the connector 27 is connected to the connector 26 to perform switching corresponding to each commercial power. The numbers “1” to “6” described in the connectors 25, 26, and 27 indicate the pin numbers of the connectors. The connectors 25 and 26 of the switching circuit 23 and the connector 27 of the power transformer 24 are connected to the same pin numbers.

FIG. 3 is a diagram for explaining the flow of current in the rectifying unit 8C and the smoothing unit 9C of the rectifying / smoothing unit when AC 100 V is used. When the connector 27 is connected to the connector 25, the circuit shown in FIG. AC between terminals S and R in FIG.
When 100 V is input, the current d flowing from the terminal R becomes
By returning to the terminal S through the diode 8c, the inrush current limiting circuit 10a, and the electrolytic capacitor 9a, the electrolytic capacitor 9
Charge a. The current e flowing from the terminal S passes through the electrolytic capacitor 9b, the inrush current control circuit 10b, and the diode 8f, and returns to the terminal R, thereby charging the electrolytic capacitor 9b. Diodes 8b and 8e are each electrolytic capacitors 9
A and 9b are protected from applying a reverse voltage. Diodes 8a and 8d are not used when AC100V is input. On the path of the currents d and e, there are inrush current limiting circuits 10a and 10b, respectively, which limit an excessive current (rush current) flowing when the power is turned on.

Here, the voltage C converted into a DC power supply is expressed by the following equation (1). C = input AC voltage (100 V) × 2 × 2 ^1/2 ８０280 V (Equation 1) In the power transformer 24, the output voltage f output to the winding n3 is expressed by the following equation 2. f = (m3 / m1) × input AC voltage = (m3 / m1) 100V _ac (Formula 2) Here, the number of turns of the winding n1 is m1 The number of turns of the winding n2 is m2 m1 = m2 The number of turns of the winding n3 is m3.

FIG. 4 is a diagram for explaining the flow of current in the rectifying unit 8C and the smoothing unit 9C when using AC 200V. When the connector 27 is connected to the connector 26, the circuit shown in FIG. When AC200V is input between the terminals S and R, full-wave rectification is performed by the rectifier 8C, and a current flows in a loop of the current g to charge the electrolytic capacitor. There are inrush current control circuits 10a and 10b along the path of the current, and perform the same operation as described above. The voltage C converted into the DC power supply is expressed by the following equation 3, which is the same as the voltage C (see equation 1) in the circuit when AC 100 V is used (FIG. 3). C = input AC voltage (200 V) × 2 ^1/2 ８０280 V (Equation 3) In the power transformer 24, the output voltage f is f = {m3 / (2 · m1)} × 200 = (m3 / M1) × 100 V _ac (Equation 4), which is also the same as the voltage f (see Equation 2) in the circuit (FIG. 3) when 100 V AC is used. In FIG. 4, a description is given of a three-phase 200 V.
A similar function can be realized even when V power is input.

As described above, the DC power supply voltage C and AC power supply voltage f output from the connector 34 to the actuator power supply circuit 17 with respect to different power supply inputs such as AC 100 V input and AC 200 V input are obtained only by switching the connection of the connector 27. Can be kept constant. Also,
With such a configuration, even if the connector 27 is forgotten to be connected to both the connectors 25 and 26, the function of the rectifying unit 8C is full-wave rectification shown in FIG. 4 and a voltage doubler circuit is not formed. Is converted into the input AC voltage × 2
^No matter which of AC100V or AC200V is input, it is 280V, AC10 when AC200V is input.
The voltage becomes 140 V at the time of inputting 0 V, which is suppressed to 280 V or less, which is a normal voltage, and does not damage equipment.

As described above, according to the control box 3 of the sewing machine of this embodiment, the switching circuit 23 switches the rectifying method of the rectifying unit 8C and the winding n of the power transformer 24.
1 and n2 at the same time, a plurality of external AC power supplies (for example, AC100V and AC200V) can be used while one control box and one sewing machine motor 2 are used.
(V-system commercial power supply). The main configuration required for this switching is a rectifying / smoothing section composed of a rectifying section 8C and a smoothing section 9C having two full-wave rectifiers and a voltage doubler rectifier, and two or more independent windings. Line n
Since only the power transformer 24 having 1 and n2 is provided, it can be constructed relatively inexpensively and with a small space.

In a control box of a sewing machine, a structure in which a wiring on a primary side of a power transformer and a wiring for leading an external power supply are connected by a connector has been generally used.
In this embodiment, the switching connector corresponding to the external commercial power supply is provided at the same position as the connector of the conventional power transformer and has the same function as the connector of the conventional power transformer. It is easy for a user or a manufacturer to know the presence or position, and errors such as forgetting to insert the connector 27 can be reduced.

The two inrush current limiting circuits 10a, 1
0b alone can prevent inrush current in both rectification methods of full-wave rectification and voltage doubler rectification, damage to equipment due to the inrush current, or temporarily output excessive power, and external power It is possible to avoid inconveniences such as an abnormal operation (eg, a breaker is dropped) and the sewing machine cannot be operated. Therefore, it is possible to reduce the cost and size of the circuit.

[Second Embodiment] FIG. 5 is a block diagram showing a configuration of a control box (control device) 3A of a sewing machine according to a second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Connector H1,
H2 connects the wiring on the primary side of the power transformer and the wiring for leading the external power supply, and has a conventional general configuration. The control box 3A of the sewing machine according to the second embodiment includes:
This is an example in which switching by replacement of the connector 27 in the first embodiment is changed to switching by a switch. Switching circuit 23 as switching means of this embodiment
A is composed of switches 29 and 30, and the switching of these switches 29 and 30 performs the same circuit switching as the replacement of the connector 27 of the first embodiment. These switches 29 and 30 are simultaneously and collectively switched by, for example, a three-phase switch or a relay switch.
Although the figure shows the case of using 200 VAC input, when the switches 29 and 30 are operated simultaneously, the switch operates for 100 VAC. According to the control box 3A of the sewing machine of this embodiment, the change of the external AC power supply can be easily switched with a switch with good workability.

[Third Embodiment] FIG. 6 is a block diagram showing a configuration of a control box (control device) 3B of a sewing machine according to a third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The control box 3B of the sewing machine according to the third embodiment uses connectors 31 to 33 dedicated to circuit switching as connectors for switching circuits without using the connectors H1 and H2 on the primary winding side of the power transformer 24. It is provided. A switching circuit 23B, which is a switching means of this embodiment, includes dedicated connectors 31 to 33 for switching between a circuit for AC100V and a circuit for AC200V. By connecting the connector 31 to the connector 32, the circuit for AC100V is changed. By connecting the connector 31 to the connector 33, the circuit can be switched to a circuit for 200V AC. The switched circuit configuration is the same as that of the first embodiment. The pins 1 to 4 of the connector 33 are not connected to any wiring (represented by "NC (not connect)" in the figure).

The present invention is not limited to the control boxes 3 to 3B of the sewing machine according to the first to third embodiments, and can be appropriately changed without departing from the gist of the invention. For example, the full-wave rectifier and the voltage doubler rectifier in the rectifier / smoothing unit may be switchable using two independent rectifiers instead of using the same diode.
The switching of the windings in the power transformer is performed by switching the two windings n1 and n2 in series or in parallel, and by using two independent windings having different numbers of windings. Various methods such as a method of switching windings are possible. In the control boxes 3 to 3B of the sewing machine according to the first to third embodiments, the rush current control circuits 10a and 1
FIG. 7 shows an example in which two inrush current limiting circuits are connected between the rectifying unit 8C and the smoothing unit 9C.
As shown in the figure, the smoothing capacitors 9c and 9d of the smoothing unit 9C
May be connected in series with the rush current limiting circuits 10c and 10d.

[0036]

As described above, according to the present invention, the following effects can be obtained. That is, the same sewing machine control device and sewing machine motor can cope with an external AC power supply different in AC100V and AC200V, for example, at relatively low cost and space saving. Further, switching corresponding to different AC power supplies can be performed by a simple operation of replacing a connector.

In addition, the control box is not damaged even if the operator mistakes the operation of forgetting to insert the connector. In addition, by switching with a switch instead of replacing a connector, switching corresponding to different AC power supplies can be performed with simpler work. Further, by providing only two inrush current limiting circuits, the excessive current at power-on can be limited according to the input voltage, even when using AC 100 V or when using AC 200 V, thereby reducing the circuit cost and reducing the size. I can do it.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control box of a sewing machine according to an embodiment of the present invention.

FIG. 2 is a wiring diagram showing details of a switching circuit in a control box of the sewing machine.

FIG. 3 shows AC100V in a control box of the sewing machine.
It is a figure explaining the flow of electric current in a rectification part and a smoothing part at the time of use.

[Fig. 4] AC200V in the control box of the sewing machine
It is a figure explaining the flow of electric current in a rectification part and a smoothing part at the time of use.

FIG. 5 is a block diagram illustrating a configuration of a control box of the sewing machine according to the second embodiment.

FIG. 6 is a block diagram illustrating a configuration of a control box of a sewing machine according to a third embodiment.

FIG. 7 is a circuit diagram showing a modified example of an arrangement of an inrush current limiting circuit in the control box of the sewing machine according to the first to third embodiments.

FIG. 8 is a perspective view showing a configuration example of a conventional industrial sewing machine.

FIG. 9 is a block diagram showing a configuration example of a control box of a conventional sewing machine.

FIG. 10 shows a configuration example of a rectifying unit and a smoothing unit of a control box for AC 100 V system input.

FIG. 11 shows a configuration example of a rectifying unit and a smoothing unit of a control box of an AC 200 V system input.

[Explanation of symbols]

3, 3A, 3B Sewing machine control box (control device) 4 Power switch 5 Pedal 6 Operation panel 7 Filter section 8C Rectification section 9C Smoothing section 10a, 10b Inrush current limiting circuit (rush current limiting means) 10c, 10d Inrush current limiting circuit (Rush current limiting means) 11 sewing machine motor driver 12 DC-DC converter 15 motor control means 17 actuator power supply circuit 19-21 sewing machine actuator 23, 23A, 23B switching circuit 24 power supply transformer n1, n2, n3 windings 25-27 connector 29,30 switch 31-34 connector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3B150 CE03 CE09 CE22 CE25 JA02 KA04 QA05 QA06 5H006 BB05 CA01 CA12 CA13 CB01 CB04 CB09 CC01 FA02 GA01 HA05 5H007 AA17 BB06 CA01 CB04 CB05 CC01 CC23 DA05 DB01 DB12 DC07 GA03 HA03

Claims (6)

[Claims] A rectifying / smoothing unit for rectifying and smoothing by inputting an external AC power supply; a motor drive driver for driving a sewing machine motor with the DC power rectified and smoothed by the rectifying / smoothing unit; A power supply transformer for converting a voltage by the power transformer, and an actuator driver for driving one or a plurality of actuators provided in the sewing machine with the AC power supply voltage converted by the power supply transformer. The power transformer has two or more independent windings on a primary side, and further includes a full-wave rectifier and a voltage doubler rectifier in the rectifying / smoothing unit. A control device for a sewing machine, comprising: switching means for simultaneously performing switching and switching of windings in the power transformer. 2. The control device for a sewing machine according to claim 1, wherein the switching means comprises a connector for switching the rectifying / smoothing unit and the power transformer in a batch by replacement. 3. The power supply transformer according to claim 1, wherein
3. The control device for a sewing machine according to claim 2, wherein the connector also serves as a connector for connecting a next-side wiring and the external AC power supply. 4. The control of the sewing machine according to claim 2, wherein the rectifying / smoothing section functions as a full-wave rectifier while the voltage doubler rectifier does not function when the connector is disconnected. apparatus. 5. The control device for a sewing machine according to claim 1, wherein the switching means comprises a switch for switching the rectifying / smoothing unit and the power transformer at once. 6. An inrush current limiting means for preventing an inrush current is provided on each of the positive and negative sides of the rectifying / smoothing section between the rectifying section and the smoothing section. Sewing machine control device.