JPH1169890A - Method and circuit for resetting stepping motor to excitation origin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reset a stepping motor to an excitation origin through an internal oscillator upon power interruption using charges in a capacitor for smoothing power supply. SOLUTION: If the power supply voltage drops below a predetermined level due to power interruption when a stepping motor M is stopping at a position other than an excitation origin, pulse input from an external oscillator is stopped forcibly by a power supply voltage detecting section 11 and first and second NAND circuits 12, 13. The stepping motor M is reset to an excitation origin by fourth and fifth NAND circuits 18, 20 based on a pulse waveform signal generated from an internal oscillation circuit 16 in the rotational direction determined at a rotational direction switching section 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a circuit for returning to an excitation home position of a stepping motor, and more particularly to a method for preventing a stepping motor from being displaced when the power is turned on and a stepping motor having an electromagnetic brake for vertical driving. The present invention relates to a method of returning to an excitation origin and a circuit therefor.

[0002]

2. Description of the Related Art Conventionally, as a method of returning to an excitation origin of a stepping motor M of this type, for example, there is a method as shown in FIG. According to FIG. 3, according to this method, an output signal from the logic circuit 2 is output to a driving circuit 3 by an external oscillator 1 having a home return function and a stepping motor driving logic circuit 2 connected thereto. The stepping motor M is operated by amplification.

That is, when the stepping motor M is stopped at a position other than the excitation origin, the motor M is driven in the direction of the excitation origin by the forward or reverse rotation pulse output from the external oscillator 1, and the logic circuit 2 is driven. When the excitation origin output is output to the external oscillator 1 from above, the motor M can be stopped at the excitation origin by stopping the pulse output of the external oscillator 1. However, this method has a built-in origin return function. It is expensive because an external oscillator 1 is required.

[0004]

However, in such a conventional method of returning to the excitation home position of the stepping motor M or its circuit, when the power is cut off or the power supply is forcibly cut off, the motor cannot be driven in any excited state. Since it is not known whether M will stop, when the power is turned on thereafter, the motor M will instantaneously return to the excitation origin. Then, there is a problem that a mechanism or a work incorporating the stepping motor M is vibrated, which may cause breakage or dropping.

On the other hand, the position of the stepping motor M cannot be controlled because of the open loop control, and when the power is turned on, the stepping motor M is forcibly rotated to the excitation origin determined by the drive circuit. In order to improve this, there is a method of storing an excitation sequence at the time of power-off using a CPU or a memory, but there is a problem that the cost is increased.
Therefore, at present, a simple circuit for always exciting the motor M from the excitation origin when the power is turned on has not been proposed.

[0006] The present invention has been made in view of such a point,
The purpose is to solve the above-mentioned problem, and to turn off the stepping motor after returning the stepping motor to the excitation origin by an internal oscillator by using the charge stored in the power supply smoothing capacitor when the power is turned off. Accordingly, it is an object of the present invention to provide a method and a circuit for returning to the excitation origin of a stepping motor for safely driving a mechanism by eliminating a displacement at the time of turning on the power.

[0007]

The structure of the present invention for achieving the above object is as follows.

(1) When the stepping motor is driven at a position other than the excitation origin when the stepping motor is driven via a logic circuit and a drive circuit based on a pulse signal input from the outside, a) outputting the normal rotation pulse signal when the power supply voltage is equal to or higher than a predetermined voltage by a first NAND circuit to which a normal rotation pulse signal from the outside and the detected power supply voltage are input; A second NAND circuit to which a reverse pulse signal from the outside and the detected power supply voltage are input, the reverse pulse signal is output when the power supply voltage is equal to or higher than a predetermined voltage; An OR circuit to which an excitation origin output signal is input outputs a high level signal when the power supply voltage is lower than a predetermined voltage or when the excitation origin output signal is not at the excitation origin.
(D) a third NAND circuit to which the output signal of the OR circuit and the pulse waveform signal from the oscillation circuit are input,
When the output signal of the OR circuit is at a high level, the pulse waveform signal is output, and (e) a fourth NAND to which the output of the first NAND circuit and the output of the third NAND circuit are input When the output of the first NAND circuit is at a high level, the output signal of the third NAND circuit is inverted and output as a non-inversion pulse signal. (F) The output of the second NAND circuit is Fifth NAN to be input
When the power supply voltage is equal to or higher than a predetermined voltage, the reverse rotation pulse signal is output by the D circuit. Output, and after the stepping motor is rotated to the excitation origin, the output of the oscillation circuit is stopped to return to the excitation origin.

(2) In (1), the power supply voltage is a voltage after being smoothed to a DC voltage, and after the power supply before smoothing is cut off, the smoothed voltage is maintained until the smoothed voltage decreases to some extent. By the electric charge charged to the capacitor in the circuit,
It is characterized in that the stepping motor returns to the excitation origin.

(3) In a stepping motor driven based on a pulse signal input from the outside via a logic circuit and a driving circuit, when the stepping motor is stopped at a position other than the excitation origin, the logic circuit But (a)
A first NAND circuit that receives a non-inversion pulse signal from the outside and a detected power supply voltage and outputs the non-inversion pulse signal when the power supply voltage is equal to or higher than a predetermined voltage; (b)
A second NAND circuit that receives a reverse pulse signal from outside and a detected power supply voltage, and outputs the reverse pulse signal when the power supply voltage is equal to or higher than a predetermined voltage; (c)
An OR circuit for receiving the power supply voltage and the excitation origin output signal and outputting a high level signal when the power supply voltage is lower than a predetermined voltage or when the excitation origin output signal is not at the excitation origin; A third circuit for receiving the output signal of the circuit and the pulse waveform signal from the oscillation circuit and outputting the pulse waveform signal when the output signal of the OR circuit is at a high level;
(E) an output of the first NAND circuit and an output of the third NAND circuit,
A fourth NAND circuit that inverts an output signal of the third NAND circuit when the output of the first NAND circuit is at a high level and outputs the inverted signal as a non-inversion pulse signal; and (f) the second NAND circuit When the power supply voltage is equal to or higher than a predetermined voltage, the reverse rotation pulse signal is output. A fifth NAND circuit that outputs in the rotating direction,
After the stepping motor is rotated to the excitation origin, the output of the oscillation circuit is stopped to return to the excitation origin.

Since the method and the circuit of the present invention are configured as described above, when the stepping motor is stopped at a position other than the excitation origin, the motor is rotated to the excitation origin by the output signal of the oscillation circuit, When the excitation origin is reached, the oscillation circuit is stopped, and the motor is stopped at the excitation origin.
Then, while detecting the voltage after the power supply voltage is smoothed, when the smoothed voltage drops below a predetermined voltage after the power is turned off, the stepping motor is returned to the excitation origin by the above-described method. When the power supply voltage is lower than the predetermined voltage when the motor is rotated to the excitation origin, the rotation direction is switched by the rotation direction switching unit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a method of returning to an excitation origin of a stepping motor and a circuit thereof according to the present invention. The same elements as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, a forward pulse signal input (CW-P) from an external oscillator (not shown) and a smoothed voltage of a power conversion smoothing unit 10 for converting and smoothing an AC power supply voltage to a DC voltage are detected. The output of the power supply voltage detector 11 is
While being input to the first NAND circuit 12, a reverse pulse signal input (CCW-P) from the external oscillator and the output of the power supply voltage detection unit 11 are input to the second NAND circuit 13.

The output of the power supply voltage detector 11 and the output of the excitation origin output circuit 14 of the stepping motor M are input to an OR circuit 15, and the output of the OR circuit 15 and the output of the internal oscillation circuit 16 To the third NAND circuit 17. And the output of the third NAND circuit 17;
The output of the first NAND circuit 12 is connected to a fourth NAND
The circuit 18 receives the output of the fourth NAND circuit 18 and sends the output of the fourth NAND circuit 18 to the drive circuit 3 of the motor M.
Output as P.

On the other hand, the output of the second NAND circuit 13 and the output of the rotation direction switching unit 19 such as a switch are input to a fifth NAND circuit 20 and the fifth NAN
The output of the D circuit 20 is output to the drive circuit 3 of the motor M as a reverse rotation pulse signal CCW-P.

Next, the operation of FIG. 1 will be described.
First, the first NAND circuit 12 is for switching the normal rotation pulse signal input (CW-P). When the power supply voltage is equal to or higher than a predetermined voltage, the first NAND circuit 12 controls the normal rotation by the external. A pulse signal input is output, and when the power supply voltage falls below a predetermined voltage, a constant high level is output without outputting a non-inverted pulse signal input from the outside. Similarly, the second NAND circuit 13 is for switching the reverse rotation pulse signal input (CCW-P).

The OR circuit 15 detects whether the power supply voltage is lower than a predetermined voltage by the power supply voltage detector 11 or
The stepping motor M is connected to the excitation origin output circuit 14.
The third NAND circuit 17 operates to output the pulse waveform signal from the oscillation circuit 16 to the third NAN by the third NAND circuit 17 when the output is not at the excitation origin.
Output from the D circuit 17. Further, the fourth NAND circuit 1
Numeral 8 inverts the pulse waveform signal output of the third NAND circuit 17 when the output of the first NAND circuit 12 is at a high level, and outputs the inverted signal as a non-inversion pulse signal.

The fifth NAND circuit 20 outputs a reverse pulse input from an external oscillator when the power supply voltage is equal to or higher than a predetermined voltage, and outputs a reverse pulse input when the power supply voltage is lower than the predetermined voltage.
For example, by the rotation direction switching unit 19 by manual operation,
The motor M outputs in a direction to rotate to the excitation origin,
Excitation home return is performed. The rotation direction switching unit 1
In the step 9, the stop position of the stepping motor M can be automatically detected and operated automatically by other means.

Next, FIG. 2 shows another embodiment of the present invention. In FIG. 2, instead of the driving logic circuit of FIG.
This is an example in which the PU 30 is used. The excitation origin output circuit 14, the OR circuit 15, the oscillation circuit 16, the third, fourth, and fifth NAND circuits 17, 18, and 20, and the rotation direction switching in FIG. An example in which the unit 19 is collectively replaced with a CPU 30 will be described.

In FIG. 2, when the power supply voltage falls below a predetermined voltage by the output of the power supply voltage detection unit 11, the first and second NAND circuits 12 and 13 cause
The input of the reverse rotation pulse signal to the CPU 30 is stopped. At the same time, the output of the power supply voltage detector 11 is input to the CPU 30, and the excitation state at that time is written to the memory 31. next,
When the power is turned on, the CPU 30 reads the excitation state written in the memory 31, uses the state as the excitation origin, and excites the stepping motor M, thereby eliminating the positional deviation at the time of power-on.

As described above, according to the above embodiment, the following effects can be obtained. That is, when the stepping motor M is stopped at a position other than the excitation origin,
As shown in FIG. 1, when the power supply voltage falls below a predetermined voltage, the pulse input by the external oscillator 1 is forcibly stopped,
A pulse waveform signal generated by the internal oscillation circuit 16,
The stepping motor M can be returned to the excitation origin in the rotation direction determined by the rotation direction switching unit 19.

According to this method, the motor M always stops at the excitation origin even when the power is cut off or the power is forcibly turned off while the stepping motor M is operating or stopped at a position other than the excitation origin. . Therefore, the next time the power is turned on, the motor is excited at the excitation origin, so that the motor M does not move instantaneously. By doing so, it is possible to prevent the mechanism or the work from being damaged or dropped, and to prevent the work from dropping when the power is turned on after a power failure, even when a stepping motor with an electromagnetic brake is used for the vertical drive mechanism.

The technique of the present invention is not limited to the technique in the above-described embodiment, but may be implemented by means of another embodiment having the same function. Can be changed or added.

[0024]

As is apparent from the above description, according to the method and the circuit for returning to the excitation origin of the stepping motor according to the present invention, when the stepping motor is stopped at a position other than the excitation origin, the power supply voltage is lower than the predetermined voltage. , The pulse input by the external oscillator is forcibly stopped, and the stepping motor can be returned to the excitation origin in the rotation direction determined by the rotation direction switching unit by the pulse waveform signal generated by the internal oscillator. .

When the power is turned off, the electric power stored in the power supply smoothing capacitor is used to return the stepping motor to the excitation origin by an internal oscillator, and then the motor is stopped. Thus, there is an effect that the mechanism can be safely driven by eliminating the displacement of the mechanism.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a method of returning to an excitation origin of a stepping motor and a circuit thereof according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram illustrating a conventional method of returning to an excitation origin of a stepping motor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 external oscillator 2 drive logic circuit 3 drive circuit 10 power conversion smoothing unit 11 power supply voltage detection unit 12 first NAND circuit 13 second NAND circuit 14 excitation origin output circuit 15 OR circuit 16 oscillation circuit 17 third NAND circuit 18 Fourth NAND circuit 19 Rotation direction switching unit 20 Fifth NAND circuit 30 CPU 31 Memory M Stepping motor

Claims (3)

[Claims] 1. When a stepping motor is driven at a position other than the excitation origin when the stepping motor is driven via a logic circuit and a driving circuit based on a pulse signal input from the outside, (B) outputting, when the power supply voltage is equal to or higher than a predetermined voltage, the normal rotation pulse signal by a first NAND circuit to which a normal rotation pulse signal from the outside and the detected power supply voltage are input; And a second NAND circuit to which the detected reverse power pulse signal and the detected power supply voltage are input, when the power supply voltage is equal to or higher than a predetermined voltage, the reverse power pulse signal is output. (C) An OR circuit to which the excitation origin output signal is input outputs a high level signal when the power supply voltage is lower than a predetermined voltage or when the excitation origin output signal is not at the excitation origin, and (d) an output signal of the OR circuit. When, by the third NAND circuit and the pulse waveform signal from the oscillation circuit is input,
Outputting the pulse waveform signal when the output signal of the OR circuit is at a high level; and (e) a fourth NAND to which the output of the first NAND circuit and the output of the third NAND circuit are input. When the output of the first NAND circuit is at a high level, the output signal of the third NAND circuit is inverted and output as a non-inversion pulse signal. (F) The output of the second NAND circuit is The input fifth NAND circuit outputs the reverse rotation pulse signal when the power supply voltage is equal to or higher than a predetermined voltage. When the power supply voltage is lower than the predetermined voltage, the rotation direction switching unit excites the stepping motor. Output in the direction of rotation to the origin, and after the stepping motor is rotated to the excitation origin, stop the output of the oscillation circuit and return to the excitation origin. Excitation origin return method of chromatography data. 2. The power supply voltage is a voltage after being smoothed to a DC voltage. After a power supply before smoothing is cut off, a capacitor in a smoothing circuit is charged until the smoothed voltage decreases to some extent. 2. The method according to claim 1, wherein the stepping motor returns to the excitation origin by the electric charge. 3. Based on a pulse signal input from the outside,
In a stepping motor driven via a logic circuit and a drive circuit, when the stepping motor is stopped at a position other than the excitation origin, the logic circuit detects: (a) a forward rotation pulse signal from outside; When the power supply voltage is input and the power supply voltage is equal to or higher than a predetermined voltage,
A first NAND circuit that outputs the forward pulse signal; and (b) an external reverse pulse signal and a detected power supply voltage are input, and when the power supply voltage is equal to or higher than a predetermined voltage,
(C) the power supply voltage and the excitation origin output signal are input, and the power supply voltage is less than a predetermined voltage, or the excitation origin output signal is not at the excitation origin. At this time, O which outputs a high level signal
(D) an output signal of the OR circuit and a pulse waveform signal from the oscillation circuit are input, and when the output signal of the OR circuit is at a high level, a third N which outputs the pulse waveform signal
(E) an output of the first NAND circuit and an output of the third NAND circuit are input, and when the output of the first NAND circuit is at a high level, the third NAND circuit The fourth output of inverting the output signal of
(F) receiving the output of the second NAND circuit, outputting the reverse pulse signal when the power supply voltage is equal to or higher than a predetermined voltage, and outputting the reverse rotation pulse signal when the power supply voltage is lower than the predetermined voltage. A fifth NAND circuit that outputs the rotation of the stepping motor to the excitation origin by the rotation direction switching unit. After the stepping motor is rotated to the excitation origin, the output of the oscillation circuit is stopped. And an excitation origin return circuit for a stepping motor, wherein the excitation origin return is performed.