JPS6382697A - Motor driving control apparatus of electromotive sewing machine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a motor drive control device for an electric sewing machine.
In particular, the present invention relates to a drive control device for starting a sewing machine motor, which is configured to drive the sewing machine motor at a constant low speed during the starting time after the sewing machine motor is started until it is driven at a specified speed.

[Prior Art 1] A 7fl sewing machine driven by a motor can be operated at a constant designated speed by controlling the rotation of the motor.

By the way, when starting the sewing machine, check the condition of the cloth to be sewn, the needle thread, the cloth feed setting, the condition of the lid, etc., so that the user can do the sewing work safely and without mistakes. Preferably, the motor is prevented from reaching the set speed too quickly.

Traditionally, for this purpose, for example, patent application announcements were made in 1980-
Japanese Patent No. 14594 proposes a slow starting device for a sewing machine motor. The proposed device consists of a capacitor and a resistor that charge and discharge current during the starting time from the start of the motor to the specified speed so that the rotational speed of the motor gradually increases when the sewing machine motor starts. It is set by a time constant circuit called a charging/discharging circuit, or T-C-R, and during this time, the power supply to the motor drive circuit is interrupted, and after the startup time has elapsed, power is supplied to reach the specified speed. It is intended to be controlled.

[Problems to be Solved by the Invention] In the circuit configuration of the sewing machine motor slow start device as described above, a capacitor is essential, and a large-capacity electrolytic capacitor is usually used. However, as is well known, the capacitance of a capacitor changes significantly due to the influence of ambient temperature. Therefore, if the motor startup time is set using a time constant circuit that includes a capacitor, the set motor startup time will become unstable, and the time from starting the sewing machine motor to reaching the specified speed will be longer than the user expected. It has the disadvantage that it may be shorter or slower than before, causing confusion for the user.

In addition, since the capacitance constant varies depending on the component, there will be variations in the startup time of each product.
For mass production, thorough parts management is required, such as selecting parts with small capacity tolerances.

Therefore, the present invention provides a motor drive control system for an electric sewing machine that is capable of accurately and stably starting the sewing machine motor at low speed for a predetermined starting time when starting the sewing machine motor.
II device.

timed output derivation means that starts operation and derives a predetermined output when a predetermined time elapses based on a predetermined number of pulses; and a predetermined amount of current supplied to the motor until the timed output is derived. A current limiting means,
and canceling means for canceling the current amount limiting means based on the timed output.

[Operation] When the command means outputs a start command signal, supply of current to the motor via the phase control circuit starts.

At the same time, in response to the command means, the timed output deriving means measures a predetermined time based on the number of input pulses, and derives an output when the time elapses. - As an example, the timed output deriving means includes a frequency dividing circuit using a pulse counting circuit, for example, full-wave rectification of the AC frequency 601-1z of the commercial power supply, differentiation, and 1! ′? The frequency of 120 pulse trains per second is divided at a predetermined frequency division ratio. For example, if the frequency division ratio is 7 stages, 2'-128, that is, one period is 128 times the original period (-128/120-1.066
sec,). Therefore, if a timed output is output in response to the rise or fall of this pulse, the timed output will be derived when approximately 1.07 seconds have elapsed since the instruction from the command means was issued.

The current amount limiting circuit limits the amount of current supplied to the motor by the phase control circuit to a predetermined level from when the command from the 11th order means is received until the timed output is derived. Therefore, the motor is driven at a predetermined low speed during the startup time from when the motor is started until the timed output is derived, and after the timed output is derived, the motor rotates at a specified steady speed.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the configuration, the AC plug 10 is connected to, say, a commercial power source, and supplies power to the circuit of FIG. The circuit in Fig. 1 can be roughly classified according to its functions: a phase control circuit 12 using a standard mixing bridge, a switching circuit 14 that gives commands to start/stop motor rotation, and a current supplied to the phase control circuit. A distinction can be made between a current amount limiting circuit 16 that limits the amount to a predetermined amount, and a frequency dividing circuit 18 that serves as a timed output deriving circuit.

The phase control circuit 12 includes a mixed bridge circuit consisting of a thyristor 20.22 and a diode 24.26,
The commercial power supply current supplied from the C plug 10 is rectified by this mixing bridge circuit and is applied to the motor 28. The firing timing of the thyristors 20 and 22 is controlled by the following circuit.

That is, the current from the AC plug 10 flows through the diode 30.
．． After being rectified by a resistor 32 and made into a constant voltage by a resistor 34 and a Zener diode 36, a resistor 38, an emitter collector of a transistor 40, and a variable resistor 4 for speed adjustment are applied.
2, a smoothing circuit consisting of a resistor 44 and a capacitor 26, and a circuit consisting of a programmable unijunction transistor (PUT) 48. The transistor 40 is controlled by the switching circuit 14 and the like so that the transistor 40 is turned on and off.

Here, a constant bias pressure divided by resistors 50 and 52 is applied to the gate of PUT 48. Therefore, an oscillation circuit is constituted by the PUT 48, the capacitor 46, the resistor 44, the variable resistor 12, the transistor 40, and the resistor 38, and this oscillation circuit is
The pulse transformer 54 is set in accordance with the time constant of an OR time constant circuit consisting of a capacitor 46, a resistor 44, a variable resistor 42, a transistor 40, and a resistor 38.
A pulse voltage is applied to the primary winding of the Therefore, a pulse voltage is induced in the secondary winding a of the pulse transformer 54. Based on the induced voltage, the diode 56.58
and control 2TBt through voltage dividing resistors 60, 62° 64.66 to the gate of Cyrisk 20.22, respectively:
The current is supplied and the firing timing of the thyristor is controlled.

In this way, the steady rotational speed of the motor 28 can be set to a desired value by controlling the firing timing of the thyristor 20, 22, or by setting the speed adjusting variable resistor 42 to a predetermined value. The speed can be adjusted to m.

Now, when the AC plug 10 is inserted into the outlet and the power is plugged in, the rectifier diodes 30, 32 and the stabilizing circuit 3
Power is supplied to the switching circuit 14 through a noise removal circuit consisting of 4.36, a diode 68, a resistor 70, and a capacitor 72. When the power is turned on,
Flip 70 tube 74 included in switching circuit 14
is reset by the charging Wlilf pressure of the capacitor 76, and the Q output is set to the initial state of "H" level and the Φ output is set to 1111 levels. Therefore, flip-flop 74
The transistor 40 whose base is connected to the Q output terminal of the motor 28 is off, the phase control circuit 12 does not operate, and the motor 28
has stopped.

Output "l-1" of Q output terminal of flip-flop 74
is also connected to the flip-flop 8 via the diode 78.
0 to the reset terminal of frequency divider 84 via diode 82 . Therefore, the flip 70 tube 80 is in a pit state where the 0 output is L'', and the frequency divider 84 is also in a reset state in which no output is derived.

Next, assume that the start/stop switch 86 is turned on by the user. Start/stop switch 86
is a switch that has a normally open contact and is turned on only during suppression. When the switch 86 is on, the transistor 88 is turned off, and the diode 68 . Resistance 70. capacitor 7
The current supplied through the noise removal circuit consisting of 2 is applied to the O12 terminal of the flip 70 tube 74 via a resistor 90.92. Therefore, the Q output and the Q output of the flip 70 knob 74 are inverted, the Q output becomes II L II, and the 0 output horn becomes "H". In response to the Q output of the flip-flop 70 becoming L", the transistor 40 is turned on and power supply to the phase control circuit 12 is started. However, at this time, the 0 output of the flip-flop 74 is turned on. Ga゛(
In response to this, the base of the transistor 94, which had been in the off state, becomes "H" and the transistor 94 is turned on. A current flows between the emitter and base of the transistor 96, and as a result, the potential at the base terminal of the transistor 40 increases by a constant potential determined by the voltage division ratio between the semi-fixed resistor 98 and the resistor 100. As a result, the saturation level of the transistor 40 increases. is limited, and the amount of current flowing between the emitter and collector of the transistor 40 is limited.In other words, when the start/stop switch 86 is turned on and the motor 28 starts rotating (starting In), the amount of current flowing between the emitter and collector of the transistor 40 is limited. Since the amount of current applied is controlled by transistor 40, motor 28 starts rotating at a constant low speed.

Further, when the Q output of the flip 70 knob 74 is inverted to l L 11, the reset state of the frequency divider 84 is released, and the frequency divider 84 connects the output of the stabilizing circuit 34, 36 to the differential capacitor 102 and the resistor 104. Start counting the differential pulses obtained by differentiating with the differentiating circuit.

To explain in more detail, if the frequency of the commercial power supply supplied from the AC plug 10 is, for example, 60 Hz, the commercial power supply current is converted into a wave f! by the diodes 30 and 32. ! When flushed, there are 120 pulsating valves per second. When this is differentiated by the differentiating circuit 102.degree. 104, a pulse train of 120 pulses per second is given as 1g, and this pulse train is applied to the CL terminal of the frequency divider 84.

The frequency divider 84 divides the frequency of the applied pulse to obtain another time series of pulses. In this actual droplet example, the frequency divider 84 is
For example, a 7-stage frequency divider with the IC number "TC4024" is used. Therefore, the 7-stage frequency division output Q7 of the frequency divider 84
is 2'-128, that is, one period is a pulse output 128 times as large as the original pulse period. Therefore, the Q7 output of the frequency divider 84 is 128/120=1.066 sec
, and a time sequence of pulses of approximately 1.07 seconds.

The above Q7 output of the frequency divider 84 is
When applied to the L oh child, the flip 70 knob 80 inverts the d output approximately 1.07 seconds after the start/stop switch 8G is turned on. The inverted 0 output "H" is provided as a heliset signal to the frequency divider 84 via the diode 106 and at the same time is provided to the base of the npn transistor 10B. Therefore, transistor 108 is turned on, and conversely, transistor 94, which had been on until then, is turned off. Therefore, no current flows between the emitter and the base of the transistor 96, and the base potential of the transistor 40 becomes the low level, and the transistor 40 is completely saturated. Therefore, the power commutation supplied from the AC plug 10 is supplied to the phase control 20 circuits 1 and 2 without being restricted by the transistor 40, and the phase control circuit 12 is controlled at a cross-traffic angle of 20.22. In response, motor 28 is rotated at the specified steady speed.

When the sewing machine is stopped, the start/stop switch 86
When is pressed again and turned on, the transistor 88 is turned off, the ``1-bi'' signal is input to the CL terminal of the flip-flop 74, the Q output and the O output are inverted, and the Q output becomes the topper. Therefore, the transistor 40 is turned off, the current flowing through the phase control circuit 12 is cut off, and the motor 28 is stopped.

FIG. 2 is a graph illustrating how the rotational speed of the motor 28 controlled by the embodiment of the present invention described above is changed. As shown in Figure 2, start/
When the stop switch 86 is turned on, the motor 28 rotates at a low rotational speed V, which can be set by a semi-fixed resistor 98.
Start rotation at 1. At this time, the frequency divider 84 starts a frequency dividing operation, and after an accurate fixed time, the frequency divider 84 derives an output. Depending on the output, the transistor 40 becomes completely saturated, and the motor 28 rotates at a steady rotational speed v2 set by the variable resistor 42.

Note that on the waveform diagram, when the switch 86 is turned on, the rotational speed of the motor 28 changes rapidly from V1 to V2 due to the output of the frequency divider 84, but in reality, the sewing machine needle is ! The motor 28 is under a heavy load due to the resistance of piercing the fabric being pierced and the resistance of other sewing machines.
8 changes relatively smoothly as shown by the dotted line V'. Therefore, there is no problem in practical use.

In the above description of the embodiment, an example was taken in which the frequency divider 84 was used to measure a certain period of time from the start of the motor 28. In particular, although the frequency divider 84 is a frequency divider using a pulse counting circuit that counts the number of input pulses, other frequency dividers may also be used. In such a case, the configuration of the differentiating circuits 102, 104, etc. may be changed as appropriate.

In addition, the time from when the start/stop switch 86 is turned on until the motor 28 rotates at a steady rotational speed is determined by a frequency divider, for example, a commercially available one. It may be configured with a counter timer or the like that derives an output when the number of pulses of the Li source is counted for a certain period of time.

Furthermore, in the above embodiment, it has been described that the frequency divider 84 and the counter timer operate based on the number of pulses detected from the commercial power supply. It is also possible to provide a frequency divider/counter timer that operates based on the clock generated by the reference clock generation circuit. FIG. 3 is a partial circuit diagram of such an embodiment, which replaces the divider circuit 18 of FIG. In FIG. 3, a frequency divider 84' derives a frequency divided output Qn based on the oscillation clock received from the crystal oscillation circuit 109 by 1!7. This output Qn is applied to the CL terminal of the flip 70 tube 80 in the circuit of FIG. FIG. 4 also shows that the reference clock is connected to the output terminal C of the central processing unit (CPF) 111.
An example obtained from L is shown. Recently, some electric sewing machines, so-called microcomputer sewing machines, have appeared in which a part of the sewing work is controlled by a microcomputer. In such a case, the built-in microcomputer or CPU already includes an oscillator. Therefore, the clock signal may be used to obtain a frequency-divided output as shown in FIG.

A 7y rib sewing machine to which an embodiment of the present invention is applied may have the following configuration.

That is, as shown in FIG. 5, an operating speed switching button 114 is provided at an appropriate position on the arm 112 of the sewing machine body 110. These switching buttons 114 allow the variable resistor 42 to be switched in, for example, three stages. At the same time, the semi-fixed resistor 98 (see Figure 1) is replaced by the variable resistor 98'.
, and the variable resistor 98' is switched in conjunction with the variable resistor 42. With this configuration, when the operating speed of the sewing machine is set to either low speed L1, medium speed M, or high speed H using the operating speed switching button 114,
The low starting speed set by the resistor 98 can also be changed proportionally until the sewing machine reaches the set speed when starting the sewing machine.

This allows the motor to start up extremely smoothly when starting the sewing machine.

Another 'tr1 rib sewing machine using an embodiment of the present invention, which is equipped with a layered motion type stepless changeover type operating speed changeover switch 116 as shown in FIG. So, variable +11 resistor 42
In addition, the variable resistor 98' may also be changed.

Furthermore, apart from the operating speed changeover switch 116, a sixth
A changeover switch as shown in the figure with reference number 118 is provided,
The resistance value of the variable resistor 98- may be switchable by the changeover switch.

By providing a changeover switch or the like as described above, the speed at which the sewing machine reaches steady operation upon starting can be finely adjusted to suit the user's preference.

[Effects of the Invention] As described above, according to the present invention, when starting a sewing machine, it is possible to accurately and stably drive the sewing machine motor at a constant low speed for a predetermined period of time, and the sewing machine motor can be driven accurately and stably at a constant low speed for a predetermined time period. Since the Tanabata speed of the sewing machine sometimes reaches a specified steady speed, the electric sewing machine can be easily handled by the user and can perform sewing work safely.

In addition, unlike conventional ones, it is an accurate drive control circuit based on pulse counting, rather than a charge/discharge time constant circuit using a capacitor, and it can be used as a low-speed control circuit even during mass production.
It is possible to produce products of stable quality with no variations between products.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram of a preferred embodiment of the present invention. FIG. 2 is an illustrative graph for explaining the operation of one embodiment of the present invention. FIG. 3 J3 and FIG. 4 are circuit block diagrams showing other embodiments of the frequency dividing circuit 18. 5 and 6 show examples of external views of an electric sewing machine to which an embodiment of the present invention is applied. In the figure, 12 is a phase control circuit, 14 is a switching circuit, 16 is a current amount limiting circuit, 18 is a time-limited output deriving circuit (frequency dividing circuit), 28 is a motor, 40 is a transistor, 4
2 is a variable resistor for setting the specified speed, 84.84', 8
4″ is a frequency divider, 86 is a start/stop switch, 9
6 is a pnp transistor, 98 is a semi-fixed resistor for setting the low speed at star i-time, 102 is a differential capacitor, 10
9 indicates a crystal oscillation element. (2 others) Figure 3 + Figure 5 Figure 6

Claims (9)

[Claims] (1) A motor that is energized by a commercial power source, a phase control circuit that is connected between the commercial power source and the motor, and that adjusts the rotational speed of the motor by controlling the current phase of the commercial power source, and a phase control circuit that is connected between the commercial power source and the motor, and that rotates the motor. a motor drive control device for an electric sewing machine, the motor drive control device being coupled to the phase control circuit and in response to the command means controlling the amount of current supplied from the commercial power source to the phase control circuit when starting the motor. a current amount limiting circuit that limits the amount of current to a predetermined amount; a timed output derivation device that starts operation in response to the command means and derives a predetermined output after a predetermined time elapses based on the number of pulses of the commercial power source; A motor drive control device for an electric sewing machine, characterized in that the apparatus further comprises a canceling unit for canceling the restriction of the current amount limiting circuit in response to the output of the timed output deriving unit. (2) The motor drive control device for an electric sewing machine according to claim 1, wherein the timed output deriving means includes a frequency dividing circuit using a pulse counting circuit. (3) The motor drive of the electric sewing machine according to claim 1, wherein the timed output derivation means includes a counter timer that derives the output when a certain number of pulses of the commercial power supply is counted. Control device. (4) The main body of the electric sewing machine is provided with a changeover switch that can be operated by the user, and in response to switching of the changeover switch, the amount of current limited by the current amount limiting circuit is changed. It is characterized by
A motor drive control device for an electric sewing machine according to claim 1. (5) The electric sewing machine is capable of specifying a steady operating speed to one of a plurality of predetermined speed settings, and the electric current is limited by the current amount limiting circuit in proportion to the specified steady operating speed. A motor drive control device for an electric sewing machine according to claim 1, characterized in that the amount is switched. (6) The motor drive control device for an electric sewing machine according to claim 5, wherein the electric sewing machine includes a steady operation speed changeover switch operable by a user. (7) A motor drive for an electric sewing machine, which includes a motor, a phase control circuit connected to the motor, which adjusts the rotational speed of the motor by controlling the phase of the supplied current, and a command means which instructs the motor to start rotating. The control device includes: a current amount limiting circuit coupled to the phase control circuit and configured to limit the amount of current supplied to the phase control circuit to a predetermined amount when starting the motor in response to the command means; and a reference clock generation means. , timed output derivation means that starts operation in response to the command means and derives a predetermined output when a predetermined time elapses based on the reference clock generated by the reference clock generation means; and the output of the timed output derivation means. A motor drive control device for an electric sewing machine, comprising: a canceling means for canceling the restriction of the current amount limiting circuit in response to the current amount limiting circuit. (8) The motor drive control device for an electric sewing machine according to claim 7, wherein the timed output deriving means includes a frequency dividing circuit using a pulse counting circuit. (9) The motor drive control device for an electric sewing machine according to claim 7, wherein the timed output deriving means includes a counter timer.