JPH05161396A - Driving method for stepping motor - Google Patents

Abstract

PURPOSE:To maximize a hold torque always at the time of stopping a stepping motor by driving the stepping motor through a one- and two-phase alternately excited conduction with a high resolution and by specifying the stop position of a rotor to a two-phase simultaneously excited conduction pole position. CONSTITUTION:In the title stepping motor, a rotor 4 is formed of permanent magnet, a stator 9 is divided into parts with four phases composed of A-, B-, C- and D-phases, respective stators 9 are wound by coils 11 having switches 10 and the rotor 4 is driven by one- and two-phase alternately excited conduction system. Then, when a stop command is given from a controller, the stop position-detecting element in the controller decides whether the stop position of the rotor 4 is that by one-phase excitation or by two-phase simultaneous excitation, and in the case of the stop position by one-phase excitation, the rotor is advanced by one step to stop at the next stop position by two-phase simultaneous excitation. In the stop position by two-phase simultaneously excited magnet, a large hold torque is obtained because the rotor 4 is stopped by the resultant force of magnetic forces of two-phase stators 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor driving method, and more particularly to a step motor driving method applied to a printer.

[0002]

2. Description of the Related Art Generally, for printing by a printer, a step motor called a stepping motor, a stepper, a pulse motor or the like can easily perform digital control for converting an electric pulse of an input signal into a mechanical displacement corresponding to the pulse. It is often used for this reason.

In this step motor, a rotor connected to an output shaft of the step motor uses magnetic poles or salient pole cores to which permanent magnets are applied, and a stator has a large number of electromagnets (multi-phase motor windings). Line) is used, and when the electromagnets are sequentially excited, the rotor is attracted in a direction corresponding to the exemplified electromagnets and rotated by a predetermined angle.

Further, the patterns of the currents (energization methods) applied to the windings of each phase of the step motor are 1-phase excitation, 1.
There are two-phase alternating excitation and two-phase simultaneous excitation, which correspond to 90 °, 135 °, and 180 ° energization, respectively.

When the step motor is driven by the alternating 1- and 2-phase excitation, the rotor rotates by one tooth pitch in 8 steps, the number of steps (resolution) is doubled as compared with other methods, and disorder is prevented and high speed is achieved. It has the effect of stabilizing the operation during operation. Therefore, the step motor is often used as a control motor for digitally controlling the printing operation of the printer.

[0006]

However, the method of driving the step motor applied to the printing operation of the conventional printer described above is not effective when the rotor is stopped even when the step motor is driven by alternating one- and two-phase excitation. I was ignoring the position of the phase.

Therefore, the position of the stopped rotor is either one of the one-phase excitation position and the two-phase simultaneous excitation position.

Further, the hold torque when the rotor is stopped is larger than the hold torque at the stop position in the two-phase simultaneous excitation, that is, when the rotor is in the one-phase excitation. When stopped at the stop position, the hold torque becomes the minimum. Then, when the rotor of the step motor stops at the stop position of the one-phase excitation, the stop position of the rotor of the step motor moves due to the mechanical load with various devices connected to the output shaft of the step motor, Deviation (displacement of the stop position of the rotor) occurs, and as a result, problems such as print deviation occur.

Further, since the electric power is continuously supplied even when the step motor is stopped, there is a problem that the electric power is consumed and the step motor generates a lot of heat.

The present invention has been made in view of these points, overcomes the problems of the conventional one described above, and drives a step motor by alternating one- and two-phase alternating excitation, and at the time of stopping the step motor. An object of the present invention is to provide a driving method of a step motor capable of specifying a stop position of a rotor.

[0011]

In order to achieve the above-mentioned object, a method of driving a step motor according to the present invention as set forth in claim 1 is such that the step motor is driven by energization of alternating one- and two-phase excitation, and two phases are simultaneously driven. The feature is that the step motor is stopped at the energization position for excitation.

According to a second aspect of the present invention, there is provided a method of driving a step motor according to the present invention, wherein the step motor is driven by energizing the alternating excitation of 1 and 2 phases and then the step motor is rotated at an energizing position of the two-phase simultaneous excitation. It is characterized in that the step motor is stopped and the energization of the step motor is stopped after the hold pulse is applied, and the driving is started after the start pulse is applied at the stop position when the step motor is restarted.

[0013]

According to the step motor driving method of the present invention as set forth in claim 1, the step motor has a large resolution of 1.
It is driven by energizing two-phase alternating excitation, and the stop position of the rotor of the step motor is specified as the energizing position of two-phase simultaneous excitation.
The hold torque when the step motor is stopped can always be maximized.

Further, according to the step motor driving method of the present invention as defined in claim 2, the stop position of the rotor of the step motor is specified as the energization position of the two-phase simultaneous excitation, and the step motor is energized when it is not operating. Can be stopped and the start pulse is applied at the same time as the restart, so that the phase shift that occurs when the step motor is not operating can be corrected.

[0015]

The present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a block diagram of essential parts showing an embodiment of a printer for carrying out a step motor driving method according to the present invention.

An apparatus for carrying out the step motor driving method according to this embodiment will be described with reference to FIG.

As shown in FIG. 1, the apparatus for carrying out the driving method of the present invention comprises a control unit 1 and a driving unit 2.

In the control unit 1, a step motor stop position control unit 5 for controlling the stop position of the rotor 4 of the step motor 3 described later and a step motor stop for detecting the stop position of the rotor 4 of the step motor 1 will be described. The position detector 6 is formed.

In the drive unit 2, a step motor drive unit 7 such as an input pulse distribution circuit and a pulse amplification circuit, which are not shown, and a printer drive unit 8 such as a paper feed and a carriage are formed.

The device for carrying out the stepping motor driving method according to the present invention is not limited to this embodiment as long as it can perform the operation described later.

Next, a method of driving the step motor according to this embodiment will be described with reference to FIGS.

FIG. 2 is a schematic diagram showing the main part of the step motor, FIG. 3 is a timing chart showing the energized state when the step motor is driven, and FIG. 4 is a timing chart showing the energized state when the step motor is stopped and restarted. Is.

First, the driving operation of the step motor 3 by the energizing method of the 1/2 phase alternating excitation according to the present embodiment will be described with reference to the schematic diagram of the step motor shown in FIG. 2 and the timing chart shown in FIG.

As shown in FIG. 2, the step motor 3 is
The rotor 4 is a permanent magnet, the stator 9 is an A phase,
There are four phases, B phase, C phase, and D phase, and a coil 11 having a switch 10 is wound around each stator 9. Then, the rotor 4 can be driven by applying an input pulse as shown in FIG.

First, in step ST01, the switch 10 for the coil 11a wound around the A-phase stator 9a.
a is closed, and the other switches 10b, 10c, 10d are opened. That is, the input pulse is applied only to the A phase (O
N). Then, the side of the A-phase stator 9a facing the rotor 4 is magnetized to the S pole, and the N pole of the rotor 4 is located at the A-phase position P01.
Is sucked in and stops. This stop position P01 is a position due to one-phase excitation. The stop position of the rotor 4 due to this one-phase excitation is shown by a broken line in the figure.

Next, in step ST02, the switch 1 of the coil 11a wound around the A-phase stator 9a is
0a and the coil 11 wound around the B-phase stator 9b
b switch 10b is closed and the other switches 10c, 1
Open 0d. That is, the input pulse is applied (ON) to the A phase and the B phase. Then, the stator 9 of A phase and B phase
The sides of a and 9b facing the rotor 4 are magnetized to the S pole, and the N pole of the rotor 4 stops at a position P02 intermediate between the A phase and the B phase. This stop position P02 is a position due to simultaneous two-phase excitation. The stop position of the rotor 4 due to this two-phase excitation is shown by a solid line in the figure.

Further, in step ST03, the switch 1 of the coil 11b wound around the B-phase stator 9b is
0b is closed and the other switches 10a, 10c and 10d are opened. That is, the input pulse is applied only to the B phase (O
N) Then, the side of the B-phase stator 9b facing the rotor 4 is magnetized to the S pole, and the N pole of the rotor 4 stops at the B-phase position P03. This stop position P03 is a position for one-phase excitation.

Below, B / C phase → C phase → C / D phase → D phase →
By applying the input pulses in the order of the D and A phases, the rotor 4 of the step motor 3 is rotated stepwise in the clockwise direction every 45 degrees.

When the input pulses are applied in the order of A phase → D / A phase → D phase → D / C phase → C phase → C / B phase → B phase → B / A phase, the rotor of the step motor 3 is applied. 4 can be rotated in a counterclockwise direction in steps of 45 degrees.

As described above, according to the energization method of the alternating excitation of 1 and 2 phases, the number of steps (resolution) is doubled and the rotation of the step motor is increased as compared with the energization method of applying the one-phase excitation or the two-phase simultaneous excitation. Can be smoothed.

In practice, the energization state of the input pulse to each stator is controlled not by the switch 10 described above but by a pulse distribution circuit (not shown) or the like.

Next, the operation of stopping the step motor 3 will be described with reference to FIGS. 2 to 4.

First, the controller 1 issues a stop command for the step motor 3 to the drive unit 2. Then, conventionally, as described above, the position by the one-phase excitation, for example, P shown in FIG.
The rotor 4 was randomly stopped at 01, or at a position by two-phase simultaneous excitation, for example, at P02 shown in FIG.

On the other hand, in this embodiment, the control unit 1
When a stop command for the step motor 3 is issued from the drive unit 2 to the drive unit 2, the step motor stop position detection unit 5 in the control unit 1 causes the stop position of the rotor 4 to be the position by the above-described one-phase excitation or two-phase simultaneous Judge whether the position is due to excitation, 1
In the case of the position by the phase excitation, the step motor stop position control unit 5 in the control unit 1 is advanced so that the rotor is stopped at the next position by the two-phase simultaneous excitation.
Sends a stop command to the step motor drive unit 7 in the drive unit 2. Then, the step motor drive unit 7 sends a hold pulse for stopping the step motor 3 to only the desired two phases, for example, only the A phase and the B phase as shown in FIG. The rotor 4 of the step motor 3 is stopped at the position P02 shown in FIG.

Further, when the stop position of the rotor 4 is the position by the two-phase simultaneous excitation, the step motor stop position control unit 5 in the control unit 1 directly issues a stop command to the step motor drive unit 7 in the drive unit 2. And a hold pulse is sent from the step motor drive unit 7 to the desired two phases for a desired time as described above.

Therefore, the rotor 4 of the step motor 3
Is the position due to the two-phase simultaneous excitation, the stop position P02 shown in FIG.
It will be surely stopped at any position of P04, P06 and P08. At the stop position of the rotor 4 by the two-phase simultaneous excitation, the rotor 4 is stopped by the resultant force of the magnetic forces of the two-phase stators 9, so that the rotor 4 by the one-phase excitation is used.
It is possible to obtain a magnetic force (hold torque) at the time of stop that is larger than the magnetic force of the stator 9 of one phase at the stop position.

After the step motor 3 is stopped at the desired position, the power supply to the step motor 3 is stopped until the restart. Thereby, power consumption and heat generation of the step motor 3 can be reduced.

Next, the operation of restarting the step motor 3 will be described with reference to FIGS. 2 to 4.

Now, when the step motor 3 is stopped and the rotor 4 of the step motor 3 is stopped at the intermediate position P02 between the A phase and the B phase in FIG. 2, all the phases (A phase,
Since electric power is not supplied to the B-phase, C-phase, and D-phase), when a mechanical load occurs with various devices connected to the output shaft (not shown) that rotates by the rotor 4 of the step motor 3, the output is generated. This load is reversely transmitted to the rotor 4 of the step motor 3 via the shaft, and the stop position of the rotor 4 moves clockwise or counterclockwise.

Therefore, in this embodiment, the step motor stop position control section 5 in the control section 1 sends a start command to the step motor drive section 7 in the drive section 2 and the step motor drive section 7 makes a step. A start pulse is sent to the same two phases as those to which the hold pulse for stopping the motor 4 is applied, for example, the A phase and the B phase for a desired time as shown in FIG. Then, the A-phase and the B-phase are magnetized, and the rotor 4 is reliably moved to the intermediate position P02 between the A-phase and the B-phase which is the position at the time of stop. After that, the rotor 4 at the restarting position can be moved stepwise by sequentially applying input pulses to a desired stator, and the step motor 3 can be driven.

As described above, when the step motor 3 is restarted, the start position of the rotor 4 is set by applying the start pulse to the appropriate two phases to which the hold pulse for stopping the step motor 3 is applied for a desired time. The step motor can be reliably returned to the stopped position, and the occurrence of print misalignment can be prevented.

When the rotor 4 is stopped by advancing by one step and then stopped, the advancing step by one step may be returned at the time of restart.

The present invention is not limited to the four-phase step motor shown in the above embodiment, but can be applied to a step motor having a plurality of phases such as three phases and five phases.

Furthermore, the present invention is not limited to the above embodiment, but various modifications can be made as necessary.

[0046]

As described above, according to the method of driving the step motor of the present invention, the step motor is driven by the alternating excitation of 1 and 2 phases having a large resolution, and the stop position of the rotor when the step motor is stopped is set. It is possible to specify the stop position where the hold torque is large. In addition, the starting position of the rotor of the step motor at the time of restart can be easily made the same as the position at the time of stopping, and the power can be stopped when the step motor is stopped, resulting in power consumption and heat generation of the step motor. It is possible to obtain an extremely excellent effect of reducing and.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part showing an embodiment of a printer for carrying out a step motor driving method according to the present invention.

FIG. 2 is a schematic diagram showing a main part of a step motor.

FIG. 3 is a timing chart showing an energized state when a step motor is driven in the step motor driving method according to the present invention.

FIG. 4 is a timing chart showing an energized state at the time of stop and restart in the method of driving a step motor according to the present invention.

[Explanation of symbols]

 3 Step motor 4 Rotor 9 Stator 10 Coil

Claims (2)

[Claims] 1. A method of driving a step motor, wherein the step motor is driven by energization of alternating one- and two-phase excitation, and rotation of the step motor is stopped at an energized position of two-phase simultaneous excitation. 2. The step motor is driven at the energized position of the two-phase simultaneous excitation after the step motor is driven by the energization of the 1 and 2 phase alternating excitation, and the energization of the step motor is stopped after the hold pulse is applied. At the same time, when the step motor is restarted, the driving is started after applying a start pulse at the stop position.