JPH0438194A - Apparatus for controlling stepper motor - Google Patents

Abstract

PURPOSE:To reduce a heat generation quantity largely, by feeding a driving current to a stepper motor according to the load of a body to be driven, receiving the signal from a sensing means which outputs the signal associated with the load of the body to be driven. CONSTITUTION:When a needle bar 10 is at a highest position, the phase angle of an upward axis is made to be zero degree. In this case, in the period of from about 90 degrees to about 105 degrees inclusive, wherein a large load acts on the needle bar 10 when a sewing needle 13 is stuck into a processed cloth, an emitted light from a light emission element is shaded with a shielding plate 12. Therefore, in this period, a photointerrupter 11 outputs a load signal LS of 'L' level which commands the needle bar 10 to bear a high load, and in the period other than this period, outputs the load signal LS of 'H' level which commands it to bear a low load. Still, the needle bar 10 continues to lift, and when the phase angle has reached about 260 degrees, the photointerrupter 11 outputs the load signal LS of 'L' level, but this load signal LS doesn't affect the control of a driving current. Numerals 14 and 15 denote a presser bar and presser foot respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device that automatically controls a drive current supplied to a stepping motor according to the load of a driven object.

[Prior art]

Generally, stepping motors capable of open-loop control are used in various precision mechanical devices such as electronically controlled sewing machines, printers, and precision machines.

Generally, a stepping motor is used to drive a driven body via a transmission mechanism including a speed reduction mechanism, and is configured to be driven by drive pulses from a drive circuit.

Incidentally, when the load on the driven body changes, a stepping motor used in these mechanical devices is selected that can generate a driving torque that can accurately drive the driven body even under high load. Furthermore, in order to always drive and control the driven object with high precision without losing synchronization during high loads, the stepping motor is always supplied with drive pulses with a predetermined drive current corresponding to the maximum load, regardless of the size of the load. That's what I do.

[Problem to be solved by the invention]

As mentioned above, in order to prevent step-out during high loads, a drive pulse with a drive current corresponding to the maximum load is constantly supplied to the stepping motor regardless of the load size, so power consumption is high (and the stepping motor Furthermore, if the stepping motor is driven continuously for a long time, there is a problem that the durability of the stepping motor is reduced, such as the coils being burnt out due to high heat.

An object of the present invention is to provide a stepping motor control device that can significantly reduce the amount of heat generated by a stepping motor.

[Means to solve the problem]

As shown in the functional block diagram of FIG. 1, a stepping motor control device according to the present invention is a control device for controlling a stepping motor that drives a driven body via a transmission mechanism, and in which The apparatus is provided with a detection means for outputting a signal, and a control means for receiving the signal from the detection means and supplying a driving current to the stepping motor according to the load of the driven body.

[Operation] In the stepping motor control device according to the present invention,
The control means receives a signal related to the load of the driven object from the detection means, and based on this signal, supplies a drive current to the stepping motor according to the load, that is, a small drive current when the load is low, while supplying a small drive current to the stepping motor when the load is large. A driving current is supplied to the stepping motor only when the load is large.

〔Effect of the invention〕

According to the stepping motor control device according to the present invention, the detection means and the control means are provided, and a drive current corresponding to the load is supplied to the stepping motor based on a signal related to the load of the driven body. In response to load fluctuations, the driven object can be driven with high precision with a drive torque that corresponds to the load, whether at low or high loads, and power consumption can be reduced.
Effects such as being able to significantly reduce the amount of heat generated by the stepping motor and improving the durability of the stepping motor can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

This embodiment is a case where the present invention is applied to an electronically controlled zigzag sewing machine.

There is a needle bar 10 inside the arm of the electronically controlled zigzag sewing machine.
A needle bar vertical drive mechanism that reciprocates the needle up and down, a needle bar swing drive mechanism that swings left and right, and a thread take-up mechanism that reciprocates the thread take-up up and down are incorporated. It incorporates a hook drive mechanism, a feed dog up and down movement mechanism that drives the feed dog up and down and a reciprocating mechanism, and a feed back and forth movement mechanism that drives the feed dog back and forth. , horizontal hook drive mechanism, feed dog vertical movement mechanism, and both feed longitudinal movement mechanisms are sewing machine motor 2
The needle bar 10 is driven up and down by a needle bar drive stepping motor 25 via a needle bar vertical drive mechanism, and a needle bar swinging stepping motor 26. The needle bar is oscillated by the needle bar oscillating drive mechanism.

By the way, as shown in FIG. 2, a photo-interrupter 11 having a light-emitting element and a light-receiving element is attached to the machine frame 16 near the needle bar 10, and the light-emitting element of the photo-interrupter 11 is attached to the needle bar 10. A shielding plate 12 is attached to block the emitted light emitted from the light receiving element toward the light receiving element. Therefore, as shown in FIG. 3, when the phase angle of the upper axis is 0 degrees when the needle bar 10 is at the highest position, a large load is applied to the needle bar 10 when the sewing needle 13 inserts the work cloth. Approximately 90
During a period of about 105 degrees from the needle bar 1 degree (hereinafter referred to as a high load period of 1 degree needle bar), the light emitted from the light emitting element is transmitted to the shielding plate 12.
During this period, the photo-interrupter 11 outputs an "L" level load signal LS that commands a high load, and during other periods (hereinafter referred to as the low-load period of the needle bar 10) It outputs a load signal LS at rH level that commands a low load on the needle bar IO. Incidentally, when the needle bar 10 is at a phase angle of approximately 260 degrees during its upward movement, the photo ink printer 11
outputs a load signal LS at "L" level, but this load signal LS does not affect drive current control. Reference numeral 14 is a presser bar, and reference numeral 15 is a presser foot.

Next, the control system of the sewing machine is constructed as shown in the block diagram of FIG.

The motors 25 to 27 are connected to the drive circuits 28 to 30, the speed volume 19 for setting the sewing speed is connected to the A/D converter 20, the photo ink converter 11, and the constant current power source 2.
2. The drive current switching relay 23, the start/stop switch 17 for instructing the start/stop of sewing operation, the pattern selection switch 18 consisting of a numeric keypad for selecting a desired sewing pattern, and the timing signal generator 21 are input/output of the control device C. They are connected to the interface 31, respectively.

The constant current power source 22 supplies a driving current (1) of the stepping motor 25 that provides sufficient driving torque to move the needle bar 10 up and down during the low load period of the needle bar 10, and a drive current (1) that can be used during the high load period of the needle bar 10. At this time, a drive current I2 is output that provides sufficient drive torque to move the needle bar 10 up and down against a high load. Here, the drive current I2 is set to, for example, twice the current value of the drive current 11.

A brief explanation of the timing signal generator 21 is as follows.
N slits are provided at predetermined intervals on the peripheral edge of the disc-shaped disk attached to the upper shaft, and a detection signal (clock signal) is obtained by detecting these slits with a sensor using the uppermost position of the sewing needle 13 as a reference position. The stepping motors 25 and 26 are controlled by counting these detection signals.

Next, the drive current switching relay 23 will be explained.
A drive current 11 from a constant current power supply 22 is supplied to the terminal a, and a drive current I2 is supplied to the terminal A. When the relay coil 24 is not excited, the terminal a and the terminal C are connected, and the drive current 11 is supplied from the terminal C to the stepping motor 25 via the drive circuit 28, and the relay coil 24 is excited. When the motor is running, the terminal C is connected to the terminal C, and the drive current 12 is supplied from the terminal C to the stepping motor 25 via the drive circuit 28.

The control device C includes a CPU 33, an input/output interface 31 connected to the CPU 33 via a bus 32 such as a data bus, a ROM 34, and a RAM 35.

The stitch pattern data memory of the ROM 34 stores needle position data for each sewing operation for each of a large number of stitch patterns such as letters, symbols, and marks in correspondence with pattern numbers.

The program memory of the ROM 34 stores information based on the set speed signal output from the speed volume 19, the start signal and stop signal output from the start/stop switch 17, the timing signal from the timing signal generator 21, and the stitch pattern data. A control program for controlling the motors 25 to 27, a drive current control program for controlling the drive current supplied to the stepping motor 25 for driving the needle bar, and the like are stored.

The RAM 35 includes various types of memories that temporarily store the results of arithmetic processing performed by the CPU 33 and a timing signal generator 21.
A counter for counting the detection signal outputted from the phase angle from a phase angle of 0 degrees is provided.

Next, a driving current control routine performed by control device C of the sewing machine will be described with reference to the flowchart of FIG. In addition, Si (i=1.2.3,...) in the figure
is each step.

When the power is turned on to the sewing machine, this control is started. First, initial settings such as setting each stepping motor 25 and 26 to the initial setting position are executed (Sl), and when the start/stop switch 17 is turned on ( S2: Yes), constant current voltage if! 22 is activated (S3), the load signal LS from the photo ink club 11 is read (S4), and when the load signal LS is at the "rH" level, that is, during the low load period of the needle bar 10 (S5: No), The drive of the drive current switching relay 23 is stopped, the drive current 11 is supplied to the stepping motor 25, and the stepping motor 25 is driven with the drive current 11 (S6).

At the same time, drive control of the stepping motor 26 and the sewing machine motor 27 is started. Moreover, even if the read load signal LS is at "L" level (S5: Yes),
When the count value I of the counter is larger than N/2, that is, during the low load period (S7: No), the process moves to S6.

On the other hand, when the read load signal LS is at the “L” level and the count value I is smaller than N/2, that is, when the needle bar 10 is in a high load period (35・S7: Yes), the drive current switching relay 23 is activated. Stepping motor 25
A driving current I2 is supplied to the stepping motor 25.
is driven by the drive current I2 (S8). Then, start
When the stop switch 17 is turned off (S9: Ye
s), the constant current power supply 220 operation is stopped (SlO), and S
Return to 2. As a result, the stepping motors 25 and 26 and the sewing machine motor 27 are stopped.

As explained above, the stepping motor 25 uses a drive current of 1 during the low load period only when the needle bar 10 is in the high load period.
Since it is driven with a drive current I2 larger than 1, the needle bar 10 and the balance can be driven with high precision with a drive torque that corresponds to the load, whether under low load or high load, and power consumption can be reduced.
The amount of heat generated by the stepping motor 250 can be significantly reduced, and the durability of the stepping motor 25 can be improved.

Note that the start timing and end timing of the high load period of the needle bar 10 may be determined by counting the detection signal output from the timing signal generator 21 with reference to the uppermost position of the sewing needle 13. However, it is also possible to set the magnitude of the drive current 11-72 according to the magnitude of the load.

Furthermore, based on the set speed from speed volume 19,
The time up to the start timing of the high load period of the needle bar 10 with reference to the uppermost position of the sewing needle 13 and the time of the high load period may be calculated.

[Second Embodiment] Next, as shown in FIG. 6, in a sewing machine in which a take-up lever (the path shown) is driven by a stepping motor for driving the take-up lever via a reciprocating take-up drive mechanism, the stepping motor for driving the take-up lever is The drive current supplied to the balance may be controlled according to the load of the balance.

That is, during the period from the phase angle of about 10 degrees to the uppermost position of about 68 degrees, the thread take-up is in a high load period because the needle thread loop is finally tightened and the needle thread is let out. Moreover, the load increases as the position approaches the top position. Therefore, the timing signal generator 21 detects the start phase angle θ1 of the first high load, the start phase angle θ2 of the second high load, the start phase angle θ3 of the third high load, and the end phase angle θ4 of the third high load. Each is determined by counting the signals, and the drive current supplied to the stepping motor for driving the balance is controlled by a PWM method (pulse width modulation method) according to these phase angles θ1, θ2, θ3, and θ4.

That is, when the start/stop switch 17 is turned ON and the balance is in a low load period other than a high load period, a drive current that has a predetermined reference duty ratio and generates enough drive torque to move the balance up and down. While supplying I6 to the stepping motor, by sequentially increasing the duty ratio of each of the first to third high load periods from the reference duty ratio, drive current ■7, drive current I8, and drive current I9, which are larger than drive current ■6. are controlled to be supplied to respective stepping motors for driving the balance.

In this case as well, the same effects as in the embodiment described above can be obtained.

It goes without saying that the present invention can be applied to the control of needle bar swinging stepping motors, hook driving stepping motors, electronic typewriters, and stepping motors used in various control devices.

[Brief explanation of the drawing]

Figure 1 is a functional block diagram showing the configuration of the present invention, Figures 2-
Fig. 6 shows an embodiment of the present invention, Fig. 2 is a partially schematic front view of the sewing machine showing the needle bar and presser foot, Fig. 3 is a time chart showing the vertical movement of the needle bar, and Fig. 4 is a time chart showing the vertical movement of the needle bar. FIG. 5 is a block diagram of the control system of the sewing machine, FIG. 5 is a schematic flowchart of the drive current control routine, and FIG. 6 is a time chart showing the vertical movement of the take-up lever according to the second embodiment. 10... Needle bar, 11... Photo interrupter, 13
・・Sewing needle, 21・・Timing signal generator, 22・
・Constant current power supply, 23... Drive current switching relay 2
5. Stepping motor for driving the needle bar, 35 ・ 33 . . CPU. RAM. 34. ROM. ·Control device.

Claims (1)

[Claims] (1) A control device for controlling a stepping motor that drives a driven body via a transmission mechanism, comprising: a detection means for outputting a signal related to a load on the driven body; and upon receiving a signal from the detection means, A stepping motor control device comprising: a control means for supplying a drive current to the stepping motor according to a load of a driven body.