JP2002027793A - Stepping motor drive method and drive apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor drive method and apparatus in which noise and vibration due to a play of construction member are reduced at the time of executing through-up of a stepping motor. SOLUTION: A controller 11 transmits, during the predetermined time from start of drive, a drive signal of the frequency which is lower than the frequency when the stepping motor 13 is driven at the predetermined speed, and the stepping motor drive 12 drives the stepping motor 13 depending on the drive signal. Consequently, the stepping motor 13 rotates at a lower speed and a mechanism part 14 also starts to move slowly. In this case, the components formed with play in the construction part 14 are slowly placed in contact with each other, and an attitude during the movement is stabilized through a small amount of play. Thereafter, the through-up is executed for acceleration. As a result, a play of the construction part 14 can be controlled and noise and vibration can also be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a stepping motor and a driving device using the stepping motor.

[0002]

2. Description of the Related Art A stepping motor is used as a means for driving a mechanism member in various apparatuses. FIG.
FIG. 3 is a perspective view schematically showing a stepping motor and a mechanism member driven by the stepping motor. In the figure, 1
3 is a stepping motor, 21 and 23 belts, 22 is a pulley, 24 is a guide rod, 25 is a carriage, 26 is a fastening part, and 27 is a guide part. Stepping motor 13
As the belt 21 rotates, the belt 2 rotates.
One rotation is transmitted to the belt 23 via the pulley 22. The carriage 25 is attached to the belt 23 at the fastening portion 26.
It is fixed to. Therefore, the carriage 25 moves with the belt 23 by the rotation of the belt 23. Further, the carriage 25 allows the guide rod 24 to pass through the guide portion 27. Thereby, the carriage 2
5 moves left and right along the guide rod 24. For example, in the case of a scanner, by providing optical components such as a mirror and a fluorescent lamp on the carriage 25, the carriage 25 is moved at a predetermined speed,
It becomes possible to read an image of a document or the like at a predetermined resolution.

[0003] Incidentally, the stepping motor cannot be driven rapidly at a predetermined rotation speed or stopped suddenly. Therefore, conventionally, when the rotation of the stepping motor is started, a through-up operation in which the frequency of the drive signal for driving the stepping motor is gradually increased to gradually increase the rotation speed of the stepping motor 13 is executed. When the motor stops, the frequency of the drive signal is gradually reduced, and a through-down operation is performed in which the rotation speed of the stepping motor 13 is gradually reduced.

FIG. 4 is an explanatory view of rattling in an example of a mechanism member caused by rotation of a stepping motor, and FIG. 5 is a graph showing an example of a moving speed of a carriage in a conventional carriage drive. The reference numerals in the figure are the same as those in FIG. The carriage 25 is in contact with the guide rod 24 via a bearing (not shown) provided on the guide 27. A play is provided between the bearing and the guide rod 24 to smooth the movement of the carriage when sliding the carriage left and right. Although this play is very small, as shown in FIG. 4, when the carriage 25 is slid along the guide rod 24, the carriage 25 slightly rotates. For example, when trying to move the carriage 25 rightward in the figure, the movement of the upper end of the carriage 25 in the figure is delayed, and the carriage 25 moves slightly rotated leftward. Conversely, the carriage 2 moves leftward in the figure.
If the user wants to move 5, it will move with a slight rotation in the clockwise direction.

When the movement of the carriage 25 is started and the acceleration is performed by executing the above-mentioned through-up, the posture is changed from the stopped posture to a slightly rotated posture when moving.
At this time, if a large force is applied due to rapid acceleration, the carriage 25 rattles due to a collision between the guide portion 27 and the guide rod 24 or the like. Therefore, as shown in FIG. 5, the moving speed of the carriage 25 fluctuates irregularly. Such rattling causes noise and vibration.
It is considered that if there is no play between the mechanism members, the posture such as rotation will not change, and there will be no rattling. But,
In order to operate the above-mentioned mechanism members smoothly, it is essential to provide a play between the mechanism members, and it is difficult to solve the problem by not providing the play.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in view of the above circumstances, and in performing a step-up of a stepping motor, a stepping motor in which noise and vibration due to rattling of mechanical members is reduced. It is an object to provide a driving method and a driving device.

[0007]

According to the present invention, in a stepping motor driving method, after driving the stepping motor for a predetermined time from the start of driving at a frequency lower than the frequency at which the stepping motor is driven at a predetermined speed,
The present invention is characterized in that the driving frequency is gradually increased to the frequency at the time of driving at the predetermined speed.

According to another aspect of the present invention, there is provided a driving device for driving a mechanism member, comprising: a stepping motor for driving the mechanism member; and control means for controlling the driving of the stepping motor. At the start of driving, after driving the stepping motor at a frequency lower than the frequency at which the stepping motor is driven at a predetermined speed for a predetermined time, drive the stepping motor while gradually increasing the driving frequency to the frequency at the time of driving at the predetermined speed. It is characterized by performing.

The above-mentioned rattling between the mechanical members appears particularly when the mechanical members are rapidly accelerated from a stopped state, and does not rattle at a low speed. In addition, even if it accelerates while moving, it does not rattle so much. Utilizing such characteristics, in the present invention, first, the stepping motor is driven for a predetermined time from the start of driving of the stepping motor at a frequency lower than the frequency at which the stepping motor is driven at a predetermined speed, that is, lower than the predetermined speed. To rotate the stepping motor to start the movement of the mechanism member at a low speed. As a result, the play of the mechanism member when starting the movement from the stopped state is reduced. If the vehicle moves at a low speed, it does not rattle so much even after acceleration, so that the above-described through-up operation can be performed. In this way, it is possible to prevent rattling of the mechanism members at the start of driving and reduce noise and vibration.

The predetermined time for performing such low-speed driving is such that at least one of the driving times is driven by the rotation of the stepping motor, and the time is sufficient for the mechanical members arranged with play to come into contact with each other when the movement starts. Good. When the mechanism members arranged with play come into contact with each other, the posture of the moving mechanism member is stabilized, and the mechanism member moves without rattling against the subsequent acceleration.

[0011]

FIG. 1 is a block diagram showing an embodiment of a stepping motor driving method and a driving apparatus according to the present invention. In the figure, 11 is a control unit, 12 is a stepping motor drive unit, 13 is a stepping motor, and 14 is a mechanism unit. The control unit 11 sends a drive signal for driving the stepping motor 13 to the stepping motor drive unit 12. As a result, the stepping motor 13 is driven to rotate, and the mechanism unit 14 is operated. When the rotation drive of the stepping motor 13 is started, before the through-up operation is performed, the drive signal of a frequency lower than the frequency at which the stepping motor 13 is driven at a predetermined speed is used from the start of the driving of the stepping motor 13. It is controlled to rotate for a predetermined time. Thereafter, the frequency of the drive signal is gradually increased to perform the through-up, and the stepping motor 13 is rotated at a predetermined speed. Before driving the stepping motor 13, for example, the stepping motor 13
In some cases, the setting of the current value and the setting of the excitation mode when driving the motor may be performed. Further, when stopping the operation of the mechanism section 14, the through-down is performed by gradually lowering the frequency of the drive signal, and the rotation speed of the stepping motor 13 is gradually reduced and stopped. The control unit 11 may also be used as a control unit of each unit in addition to the control of the stepping motor 13.

The stepping motor drive unit 12 responds to the drive signal sent from the control unit 11 by, for example,
A stepping motor 1 generates a magnetic excitation phase according to a predetermined magnetic excitation mode such as a 1-2 phase or a 3-phase, and generates a drive current according to a drive signal according to a preset current value.
3 to drive the stepping motor 13.

The stepping motor 13 is driven by the stepping motor drive section 12 and rotates. For example, in the case of the constant current drive, the stepping motor drive unit 12
A predetermined torque is generated by the input current from the motor, and the motor rotates. At this time, the rotation speed changes according to the speed of change of the magnetic excitation phase from the stepping motor drive unit 12. The stepping motor 13 operates the mechanism section 14 by rotating. Note that the stepping motor 1
As 3, various excitation type motors such as three-phase, four-phase, and five-phase can be applied.

The mechanism section 14 is driven by the stepping motor 13 and performs a predetermined operation. For example, if the driving device of the present invention is applied to a scanner, the mechanism unit 14 controls the rotation of the carriage 25 on which the optical system components and the like are mounted and the stepping motor 13 as shown in FIG. It can be composed of belts 21 and 23 for transmitting and converting to linear motion. of course,
In addition to the movement of the carriage 25 in the scanner, various types of mechanism members for various uses may be used.

Next, an example of the operation of the stepping motor driving method and the driving apparatus according to the embodiment of the present invention will be described. FIG. 2 is a graph illustrating an example of a change in the rotation speed of the stepping motor and the movement speed of the driving unit when the driving of the stepping motor starts. In addition,
In the following description, a specific example of the mechanism section 14 will be described as having a configuration as shown in FIG.

When the driving of the stepping motor is started, first, the control unit 11 sends a driving signal having a frequency lower than the frequency at which the stepping motor 13 is driven at a predetermined speed to the stepping motor driving unit 12. . The stepping motor drive unit 12 drives the stepping motor 13 according to the low frequency drive signal. Then, the stepping motor 13 starts rotating, is driven by the slow change of the magnetic excitation phase from the stepping motor drive unit 12, and rotates at a low speed. This low-speed rotation is performed for a predetermined time from the start of driving of the stepping motor 13. In FIG. 2, the driving start time is t1
The period during which the stepping motor 13 rotates at low speed is shown as t1 to t2.

When the stepping motor 13 starts rotating, the mechanism section 14 starts to move by transmitting this rotational movement. For example, if the mechanism section 14 is the carriage 25 as shown in FIG. 3, as shown in FIG.
Start sliding left or right along 4. At this time,
The carriage 25 rotates slightly so that the bearing of the guide portion 27 and the outer peripheral surface of the guide rod 24 abut. However, since the stepping motor 13 is rotating at a low speed and the carriage 25 starts operating slowly, the rotation of the carriage 25 also becomes slow, and the rattling caused by the collision between the bearing and the guide rod 24 or the like is caused. Also less.

Therefore, while the stepping motor 13 is rotating at a low speed, the mechanism members arranged with play of the mechanism portion 14, for example, the guide portion 2 of the carriage 25.
The bearing in 7 can be brought into contact with the guide rod 24. In addition, since the movement of the mechanism section 14 is slow, the mechanism members can be brought into gentle contact with each other,
Noise and vibration can be reduced.

The operating speed of such a mechanism section 14 is shown in FIG.
(B) shows the period from t1 to t2. When the driving of the mechanism section 14 is started at time t1, although there is some speed fluctuation due to collision of the mechanism members due to play, the fluctuation stops immediately and the speed is stabilized.
In addition, the period t1 to t2 of the low-speed movement in FIG. 2 may be set to be longer than a time sufficient for bringing the mechanism members arranged with such play of the mechanism unit 14 into contact with each other.

As described above, the stepping motor 13
Is rotated at a low speed, and when the mechanism section 14 operates to some extent,
The posture of the mechanism member in the mechanism section 14 is stabilized. If the posture during the movement is stabilized in this way, the posture is unlikely to collapse even when accelerated. Therefore, in the present invention, after driving at a low speed as described above, the rotation of the stepping motor 13 is accelerated to a predetermined number of revolutions by the through-up, and the moving speed of the mechanism unit 14 is also accelerated.

That is, the control unit 11 causes the stepping motor drive unit 12 to gradually increase the frequency of the drive signal. The stepping motor drive unit 12 drives the stepping motor 13 according to the drive signal, so that the rotation speed of the stepping motor 13 gradually increases. The through-up is performed in this manner. Along with this, the operation speed of the mechanism section 14 also increases. At this time, the speed change of the stepping motor and the mechanism 1
The change in the operation speed of No. 4 is shown in periods t2 to t3 in FIGS. 2A and 2B.

As can be seen from a comparison between FIG. 2B and FIG. 5, according to the present invention, it is understood that the speed of the mechanism section 14 hardly fluctuates, and the mechanism section 14 is accelerated without rattling. . While driving at a low speed as described above, the mechanism 1
4 are in contact with each other, and the posture during movement thereof is stable.
The rattling can be reduced, and the generation of noise and vibration can be suppressed.

After that, the control unit 11 sends a drive signal of a predetermined frequency to the stepping motor drive unit 12,
The stepping motor drive unit 12 drives the stepping motor according to the drive signal. As a result, the stepping motor 13 rotates at a predetermined speed, and the mechanism unit 14 also moves at a predetermined speed. When stopping the mechanism unit 14, the control unit 11 executes a through-down,
That is, the frequency of the drive signal is gradually reduced, and the stepping motor drive unit 12 drives the stepping motor according to the drive signal, thereby reducing the rotation speed of the stepping motor 13. Therefore, the mechanism 1
The moving speed of No. 4 also decreases and stops.

When controlling the rotation speed of the stepping motor 13 as described above, it is more preferable to control the rotation torque of the stepping motor 13 as well. Mechanism 14 at low speed
When the motor is driven, the rotational torque of the stepping motor 13 is not so necessary. If the same rotational torque as when driving at a predetermined rotational speed is given, excessive torque is generated and transmitted to the mechanism unit 14. Is done. In order to prevent this, it is preferable to control so that a small rotation torque is generated while rotating at a low speed, and to increase the rotation torque as the rotation speed increases.

For example, in the case of the stepping motor 13 that performs constant current driving, the current during driving may be controlled. That is, while the stepping motor 13 is rotating at a low speed, the driving current is reduced and the stepping motor 13 is rotated with a small rotating torque,
The drive current may be increased as the rotation speed of the stepping motor 13 is increased, and the rotation torque may be increased. Such control of the rotational torque may be performed also during the through-down.

In the above description of one example of the operation, the case where the carriage in the scanner as shown in FIG. However, the present invention is not limited to this.For example, in a printer such as moving a carriage or transporting a paper, or a copying machine or a facsimile machine including a scanner or a printer as a component, and further, various devices for consumer use, industrial use, etc. The present invention can be applied to any use for driving a mechanism using a stepping motor.

[0027]

As is apparent from the above description, according to the present invention, when the driving of the stepping motor is started,
The stepping motor is rotated at a constant speed for a predetermined time by a driving signal having a lower frequency than the frequency at the time of driving at a predetermined speed. As a result, when the mechanical members arranged with play come into contact with each other, not much impact is applied,
The movement can be started immediately in a stable posture.
In addition, if the vehicle is moving in such a stable posture, the posture is not easily collapsed even when the vehicle is accelerated, and the vehicle can be accelerated to a predetermined speed. Therefore, it is possible to reduce the rattling of the mechanism member during the acceleration from the start of the driving of the stepping motor to the predetermined speed, thereby suppressing the generation of noise and vibration. In addition, such a reduction in rattling of the mechanism member does not require any special modification to the mechanism member, so that there is also an effect that the cost does not increase.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a stepping motor driving method and a driving device according to the present invention.

FIG. 2 is a graph illustrating an example of a change in a rotation speed of a stepping motor and a movement speed of a driving unit at the start of driving of the stepping motor.

FIG. 3 is a perspective view schematically showing a stepping motor and a mechanism member driven by the stepping motor.

FIG. 4 is an explanatory diagram of rattling in an example of a mechanism member caused by rotation of a stepping motor.

FIG. 5 is a graph showing an example of a moving speed of a carriage in a conventional carriage drive.

[Explanation of symbols]

11: control unit, 12: stepping motor drive unit, 13
... Stepping motor, 14 mechanism, 21 and 23 belts, 22 pulley, 24 guide rod, 25 carriage, 26 fastening part, 27 guide part.

Claims (3)

[Claims] 1. A driving frequency for driving a stepping motor at a lower frequency than a frequency for driving the stepping motor for a predetermined time from the start of driving of the stepping motor, and then gradually increasing to a frequency for driving the stepping motor at the predetermined speed. A stepping motor driving method characterized by increasing the stepping force. 2. The system according to claim 1, wherein the predetermined time is a time sufficient for at least one of the mechanical members arranged with play driven by the rotation of the stepping motor to come into contact with each other. 4. The method for driving a stepping motor according to item 1. 3. A driving device for driving a mechanism member,
A stepping motor that drives the mechanism member; and a control unit that performs drive control of the stepping motor, wherein the control unit determines a frequency at which the stepping motor is driven at a predetermined speed when the stepping motor starts driving. A driving device for driving the stepping motor while gradually increasing the driving frequency to a frequency for driving at the predetermined speed after driving at a low frequency for a predetermined time.