JPS5946628B2 - Electric sewing machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electric sewing machine, and its main purpose is to temporarily stop the basting stitch of the sewing machine, that is, the needle near the top dead center, and control the needle stop period for cloth feeding. An object of the present invention is to provide an automatic basting control device that automatically performs re-rotation.

Conventional automatic basting devices generally use a combination of a mechanical one-stitch device using a declutching mechanism, etc., and an electrical intermittent circuit, resulting in a complex mechanical structure and poor durability. There were drawbacks such as poor performance and noise generation.

In order to solve these drawbacks, the present invention attempts to perform automatic basting operations electrically without using the above-mentioned complicated mechanism.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a control circuit using a thyristor, in which 1 is an AC power supply, 2 is a control circuit using a thyristor, and
is a sewing machine motor, 3 is a thyristor, 4 is a changeover switch for switching between normal stitching and basting stitches, and each has an interlocking contact piece c.
, c' are on the contact a, a' side (a' is an idle terminal), and when the sewing start switch 5 is closed, the speed control is composed of a resistor T, a variable resistor 8, an electrolytic capacitor 9, and a diode 10. The divided voltage of the reference voltage generation circuit for
1 is received and input to the gate of the thyristor 3 via the diode 6, and the current of the thyristor 3 is changed in phase by varying the divided voltage continuously by the contactor 11 or in steps by changing taps, etc. The speed of the sewing machine motor 2 is controlled from low speed to high speed. In addition,
12 is a gate protection resistor of the thyristor 3. resistance 1
3. A semi-fixed resistor 14, an electrolytic capacitor 15, and a diode 16 constitute a reference voltage generation circuit for stopping at a fixed position.
Each contact piece of the changeover switch 4 is set to the contact b, b' side, and when the sewing start switch 5 is closed, the semicircular constant resistance adjustment contact IT receives the divided voltage of the reference voltage generation circuit, which will be described later. The normally closed switch 22 is used to input the gate of the thyristor 3 and rotate the sewing machine motor 2 at a constant low speed.

18 is a needle position detection device, which has a magnet 21 attached to a rotating body 20 attached to an upper shaft 19, and opens an adjacent normally closed reed switch 22 when the magnet 21 reaches a fixed position. It's getting old.

29 is a photocoupler, and a Cds element 24 is connected to the gate of the thyristor 3 in parallel with the reed switch 22, and the Cds element is always in a high resistance state and has an open circuit function, so that the light emitting diode 25 is energized. When it receives the light emitted by the thyristor 3, it has a low resistance and equivalently becomes a closed circuit to drive the thyristor 3 again.

Note that 26 is a diode for protecting the light emitting diode 25. Reference numeral 28 denotes a thyristor for generating a re-drive signal. When the reed switch 22 is open and the thyristor 3 is out of conduction, the thyristor 28 becomes conductive temporarily by the firing operation described later, and the resistance 27 is turned on. The light emitting diode 25 is energized through the Cds element 24 to have a closing function, the thyristor 3 is made conductive, and the motor is rotated to cause the magnet 21 to escape from adjacent to the switch 22.

29 is an electrolytic capacitor, and when the contact d of the switch 4 is set to the b' side, charging is started via the DC charging diode 30 and the charging time adjustment resistor 31, and the constant voltage discharging element 33 receives the charging pressure. When the current reaches the discharge voltage and is operated, it becomes the base current of the transistor 36 and is discharged.

32 is a resistor, 34 is a capacitor for preventing malfunction of the discharge element 33, 35 is a semi-fixed resistor for adjusting discharge time, and 37 is a base protection resistor of the transistor 36.

The collector of the transistor 36 is a resistor 38 and a diode 3.
9, the emitter is connected to the gate of the thyristor, and the thyristor is made conductive or non-conducting at a period whose charging/discharging time is adjusted by adjusting resistors 31 and 35. Operates to establish continuity. Note that 41 is a resistor for protecting the gate of the thyristor. However, in FIG. 1, the contact pieces C, c of the switch 4
When ' is changed from the contact A, a' side to the contact B, d side, the sewing machine in any phase rotates at low speed until it reaches the home position, and when it reaches the home position, the reed switch 22 is opened and the thyristor 3 is made non-conductive. to set the sewing machine in a fixed position (e.g. needle top dead center).
to stop. On the other hand, the charging and discharging time of the capacitor 29 adjusted by the resistors 31 and 35 is long enough for the sewing machine to follow mechanically, and based on the charging and discharging time, the transistor 36 conducts at a certain period. The thyristor 3 is made conductive when it reaches the state of conduction, and the stopped sewing machine is re-driven to escape from the fixed position. After escape, the transistor 36 becomes non-conductive. When the reed switch 22 is closed, the sewing machine continues to rotate and stops when it reaches the home position again. The charging/discharging time is adjusted so that the transistor 36 becomes conductive after resting at the fixed position for a certain period of time, and thereafter the operations of rotation, stopping at the fixed position, resting, and re-rotation are repeated at fixed intervals. Next, an example using the logic circuit shown in Fig. 2 will be explained.The speed regulator shown in the figure is an operation section provided to change the speed of the sewing machine continuously or stepwise, and is used to switch between normal stitching and basting stitching. The device has an operating section that is designed to switch between normal sewing and basting. During normal sewing, terminal A has a logic value of 1, terminal B has a logic value of 0, and when basting, terminal B has a logic value of 1. 11 terminal A or 0 is set.

The needle position detection device has an output side that is l when the needle is at the detection position.
is set to be 0 at all other times, and when the sewing start signal generator is operated prior to starting sewing, its output side becomes l, and when the sewing machine is not used, it is set to 0. Department. The speed control circuit becomes effective via the AND circuit ANDl when the normal sewing side A of the switching device and the sewing start signal are both 1, and operates the motor drive circuit by operating the speed regulator to control the sewing machine motor. The speed is controlled during normal sewing.

F is a flip-flop circuit which is the main element for generating a fixed position stop signal and a re-drive signal for the sewing machine motor, and the positive side output terminal Q is connected to one input terminal of an AND circuit AND2, and the other input terminal of the AND circuit The basting side B of the switching device is connected to the terminal, and the output side thereof is connected to a motor drive circuit, so that when the output terminal Q is 1 during basting, the sewing machine motor is driven by the operation described later. It's getting old. The output terminal Q is connected to a delay circuit TD, and the output side of the delay circuit is connected to one input terminal of an AND circuit AND3, and the other input terminal of the AND circuit is connected to a hand position detection circuit. After the output terminal Q becomes 1, the output signal becomes 1 after the set time of the delay circuit TD, which is set to escape the sewing machine from the normal position (for example, top dead center), and the normal position. The timer T is operated via the AND circuit AND3 with the output 1 when the sewing machine escapes from the sewing machine and detects the normal position again after one rotation, and the flip-flop circuit F is connected to the terminal R for setting.
is set to 1, the positive side output Q is set to 0, the motor drive circuit is opened, and the motor braking circuit is operated for a certain period of time to stop the sewing machine motor. The negative output Q of the flip-flop circuit F is connected to a delay circuit TD2, and the delay circuit is set with a stop time of the sewing machine including a motor braking time by the timer T. The output side of the delay circuit is connected to one input terminal of the AND circuit AND4, the other input terminal of the AND circuit is connected to the sewing start signal generator, and the output terminal of the AND circuit is connected to the input terminal of the flip-flop circuit F. It is connected to the setting terminal S. In FIG. 2, when the normal sewing/basting sewing switching device is set to basting sewing and a sewing start signal is generated, if the positive side output Q of the flip-flop circuit F is l, the sewing machine motor immediately starts rotating. When the negative side output Q is 1, the positive side output Q of the flip-flop circuit F is set to 1 after a certain period of time has elapsed by the delay circuit TD2.In any case, the sewing machine motor is driven, and when the needle position is detected, the flip-flop circuit F is activated. The positive side output Q becomes 0 and the motor circuit is cut off, while the motor is braked and stopped at the time set by the timer T. Then, after the pause time set by the delay circuit TD2 has elapsed, the motor is rotated again. At the start of this re-rotation, the needle position detection signal is 1, but since the output of the delay circuit TD is 0, the braking circuit does not operate and escapes from the detection position, and the detection signal after the sewing machine rotates 1 is When l, the braking circuit operates. Thereafter, the operation of rotating, stopping at a fixed position, pausing, and rotating again is repeated at regular intervals. In the above, the setting time of the delay circuit TD is made longer so that, for example, the output of the delay circuit is 0 after 1 rotation after leaving the needle position detection position, and becomes 1 when the needle position is detected after 2 rotations. If the setting is made so that the sewing machine is set so that the sewing machine is set, two-stitch stitches can be easily performed for cutting and sewing. As described above, the present invention makes it possible to perform basting stitches using an electric circuit without installing a complicated declutching mechanism in the sewing machine, thereby eliminating the possibility of breakdowns and improving durability. It has great industrial and practical effects, such as being able to reduce noise.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram using a thyristor showing one embodiment of the control device of the present invention, and FIG. 2 is a block diagram using a logic circuit of another embodiment. In the figure, 3 is a main thyristor for driving the sewing machine, 18 is a needle position detector, 22 is a normally closed switch that opens when the needle is in the normal position, and 23
is a photocoupler, 28 is a thyristor for generating a re-drive signal,
31, 35 are semi-fixed resistors, 29 is an electrolytic capacitor, 33
is a constant voltage discharge element, and 36 is a transistor.

Claims (1)

[Claims] 1. A needle position detector that detects when the needle has reached a predetermined position, a fixed position stop circuit that stops the sewing machine drive based on a signal from the detector and stops the needle position at the fixed position, and A control device for a sewing machine, which includes a re-drive signal generation circuit that automatically generates a signal for re-driving the sewing machine after a stop period has elapsed, and repeatedly performs driving and stopping operations.