JPH11299293A - Equipment and method for controlling stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate a stepping motor in a short time by a method wherein when switching the stepping motor from a low speed rotation to a high speed rotation, the amplitude of a driving signal is compard with the reference level to judge the position of a rotor and the driving signal for a high speed rotation is started from a state one step ahead. SOLUTION: When switching a stepping motor from a low speed rotation to a high speed rotation, it is judged based on the amplitude of a driving signal output from a first driving signal generating means 1A whether a rotor of the stepping motor is near a mechanically stable position. In the case that the rotor of the stepping motor is near the mechanically stably position, a second driving signal generating means 1B is instructed to output a driving signal for moving the stepping motor to a next mechanically stable position in the rotating direction of the stepping motor. By this method, there is no wasteful state at the time of switching the stepping motor from a low speed rotation to a high speed one and thereby the acceleration time required for a high speed rotation of the motor can be remarkably shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor control device and a stepping motor control method which can be used for a disk drive or the like which moves a head using a stepping motor.

[0002]

2. Description of the Related Art In recent years, disk devices have been required to have high-speed access performance for moving a head to a target position on a disk in a short time, and disk devices using a stepping motor as means for moving the head have been commercialized. . Generally, an operation of moving a head in a disk device requires two operations, a reproduction operation and an access operation. In the reproducing operation, since the head follows a spiral track formed on the disk, it is necessary to rotate the stepping motor at a low speed and gradually move the head in the radial direction of the disk. In addition, in the access operation, it is necessary to rotate the stepping motor at high speed in order to move the head to the target position on the disk in a short time. As described above, in the disk drive in which the head is moved by using the stepping motor, there are an operation of rotating the stepping motor at a low speed and an operation of rotating the head at a high speed, and control for switching between the two rotation operations is required.

Hereinafter, a conventional stepping motor control method will be described with reference to the drawings. FIG. 5 is a configuration diagram schematically showing the internal configuration of a general stepping motor. In FIG. 5, an arrow 5a indicates a direction of a current flowing in the coil A phase, and an arrow 5b indicates a direction of a current flowing in the coil B phase. In FIG. 5, the rotor 5c has a plurality of pairs of magnetic poles N and S. The point P on the rotor starts rotating when the current 5a flowing in the coil A phase and the current 5b flowing in the coil B phase change,
Stop at a position where the balance between the magnetic force generated from each coil and the frictional load is stable. The stepping motor has several mechanical stable positions. In FIG. 5, positions 5W, 5X, 5Y, and 5Z are consecutive four mechanical stable positions among several mechanical stable positions of the stepping motor. It represents. The number of magnetic pole pairs and the number of mechanically stable positions differ depending on the type of stepping motor.

FIG. 6 is a waveform diagram showing a driving signal pattern 1 of a conventional stepping motor. FIG. 6 shows a drive signal pattern of a general stepping motor called a two-phase excitation method. This drive signal pattern is often used when the stepping motor is rotated at high speed. In FIG. 6, 6A shows a voltage waveform appearing between terminals of the coil A phase of the stepping motor, and 6B
Indicates a voltage waveform appearing between terminals of the coil B phase. In the two-phase excitation method, four states (states 6W, 6X, 6Y, and 6Z) in which the voltage between terminals of the coil is repeated periodically. In state 6W, point P in FIG. 5 moves to position 5W. Similarly, in states 6X, 6Y, and 6Z in FIG. 6, point P in FIG. 5 moves to positions 5X, 5Y, and 5Z, respectively.

FIG. 7 is a waveform diagram showing a drive signal pattern 2 of a conventional stepping motor. As shown in FIG. 7, the drive signal pattern 2 is obtained by applying a method of changing the drive signal at a constant gradient with respect to time to the two-phase excitation method. The drive signal pattern 2 is suitable when the stepping motor is rotated at a low speed. 7, 7A shows a voltage waveform appearing between terminals of the A-phase coil of the stepping motor, and 7B shows a voltage waveform appearing between terminals of the B-phase coil. In the state 7W of FIG. 7, the point P in FIG. 5 moves to the position 5W. Similarly, in the states 7X, 7Y, and 7Z in FIG. 7, the point P in FIG. 5 moves to the positions 5X, 5Y, and 5Z, respectively.

FIG. 8 is a waveform diagram showing a driving signal pattern 3 of a conventional stepping motor. FIG. 8 shows a drive signal pattern called a micro-step excitation method. This drive signal pattern is often used when the stepping motor is rotated at a low speed and minute rotation. 8, 8A shows a voltage waveform appearing between terminals of the coil A phase of the stepping motor, and 8B shows a voltage waveform appearing between terminals of the coil B phase. In the micro-step excitation method, since there are many excitation states, phase numbers (Ph00, Ph0, for example) as shown in FIG.
, Etc.) to manage the internal state. In FIG. 8, there are a total of 32 phases from phase numbers Ph00 to Ph31. By increasing or decreasing the phase numbers one by one, the drive signal pattern can be repeated periodically. As a method of obtaining the coil terminal voltage (8A, 8B) corresponding to the phase number, a constant table of the trigonometric function is provided in advance in a storage means such as a ROM or a RAM, and the voltage value corresponding to the phase number is referred to from the table. Determine the voltage between them. In the state 8W (phase number Ph00) of FIG.
Moves to the position 5W. Similarly, state 8X (phase number Ph08), state 8Y (phase number Ph16), state 8Z (phase number Ph2) in FIG.
4), the point P in FIG. 5 moves to the position 5X, the position 5Y, and the position 5Z, respectively.

[0007]

However, the conventional stepping motor control method has the following problems. For example, in the case of performing an access operation in the middle of a reproducing operation in a disk device, FIG.
It is necessary to switch the drive signal from the drive signal pattern 2 or 3 for low-speed rotation shown in FIG. 6 to the drive signal pattern 1 for high-speed rotation shown in FIG.

A problem in the switching operation will be described with reference to FIG. FIG. 9 is a waveform diagram showing a conventional drive signal switching pattern 1. FIG. 9 shows how the conventional drive signal pattern 2 for low-speed rotation shown in FIG. 7 is switched to the conventional drive signal pattern 1 for high-speed rotation shown in FIG. In FIG. 9, 9A shows a voltage waveform appearing between terminals of the coil A phase of the stepping motor, and 9B shows a voltage waveform appearing between terminals of the coil B phase. In the low-speed rotation part of FIG. 9, the state is changing from the state 9W to 9X, which corresponds to the state where the point P is moving from the position 5W to the position 5X in FIG. ing.

When switching to high-speed rotation is performed during the low-speed rotation, the conventional method outputs the pattern of the state 9X in FIG. 9 as the first drive signal for high-speed rotation. However, the point P in FIG. 5 has already moved to the vicinity of the position 5X by the low-speed rotation immediately before the switching. Therefore, in response to the drive signal in the state 9X in FIG. 9 for moving to the position 5X,
There is almost no rotational movement. Therefore, the drive signal pattern in the first state 9X after switching to the high-speed rotation is a useless state in which the effect of accelerating the rotation of the stepping motor is small. As a result, when the switching is performed by the conventional driving signal switching method, the acceleration time for rotating the stepping motor at high speed becomes long.

As described above, in the conventional drive signal switching method, as the first state in the drive signal pattern for high-speed rotation after switching, the pattern for moving the rotor to the nearest mechanically stable position in the stepping motor rotation direction is used. Was output. For this reason, when the rotor has moved to the vicinity of the mechanical stable position at low speed rotation, a drive signal pattern for moving to the same mechanical stable position at high speed rotation is output. For this reason, a useless state occurs at the time of driving signal switching, and when this driving signal switching method is used for a disk device, it causes an access operation to be delayed.

[Problem in Switching Method of Drive Signal Pattern of Micro-Step Excitation System] Next, the problem of the conventional switching method in the micro-step excitation system will be described with reference to FIG. FIG. 10 is a waveform diagram showing a conventional drive signal switching pattern 2. FIG. 10 shows how the conventional driving signal pattern 3 for low-speed rotation shown in FIG. 8 is switched to the conventional driving signal pattern 1 for high-speed rotation shown in FIG. In FIG. 10, 10A shows a voltage waveform appearing between terminals of the coil A phase of the stepping motor, and 10B shows a voltage waveform appearing between terminals of the coil B phase. In the low-speed rotation portion of FIG. 10, the state is changing from the state 10W to 10X, and the phase number changes from Ph00 to Ph07. This is because the point P in FIG.
This corresponds to a state in which the robot is moving from W to the position 5X at a low speed rotation. Here, when the switching to the high-speed rotation is performed during the low-speed rotation, the pattern of the state 10X in FIG. 10 is output as the first drive signal of the high-speed rotation in the conventional switching method. However, the point P in FIG. 5 has already moved to the phase number Ph07, that is, the vicinity of the position 5X by the low-speed rotation immediately before the switching. For this reason, almost no rotational movement is performed for the drive signal in the state 10X of FIG. 10 for moving to the position 5X. Therefore, in the pattern of the initial state 10X after switching to the high-speed rotation, the phase number only changes from Ph07 to Ph08, and the effect of accelerating the rotation of the stepping motor is small and useless. Therefore, this causes a long acceleration time for rotating the stepping motor at a high speed.

The present invention solves the above-mentioned problem by preventing the useless state when the stepping motor is switched from the low-speed rotation to the high-speed rotation, and makes the acceleration time for rotating the stepping motor at a high speed longer than before. It is an object of the present invention to provide a stepping motor control device and a stepping motor control method that can be shortened.

[0013]

In order to achieve the above object, a stepping motor control device according to the present invention comprises a first driving signal generating means for rotating a stepping motor at a low speed;
A second drive signal generating means for rotating the stepping motor at high speed; and a control means for switching between the first drive signal generating means and the second drive signal generating means, wherein the control means controls the stepping motor. When switching from low-speed rotation to high-speed rotation, the rotor of the stepping motor exists near the mechanically stable position of the stepping motor based on the amplitude of the driving signal output from the first driving signal generating means at that time. Then, if the rotor of the stepping motor is present in the vicinity of the mechanically stable position, a command is output to the second drive signal generation means, and a command from the control means is input. The second drive signal generating means rotates the stepping motor to the next mechanically stable position in the rotation direction of the stepping motor. Thereby outputting the driving signal. Therefore, the stepping motor control device of the present invention has no wasteful state when switching the stepping motor from the low-speed rotation to the high-speed rotation, and can significantly reduce the acceleration time for rotating the stepping motor at a high speed compared to the conventional art. it can.

According to another aspect of the present invention, there is provided a stepping motor control device comprising: a first driving signal generating means for rotating the stepping motor at a low speed; a second driving signal generating means for rotating the stepping motor at a high speed; Control means for switching between the drive signal generation means and the second drive signal generation means, wherein the control means switches the first drive signal generation means when the stepping motor is switched from low-speed rotation to high-speed rotation. It is determined whether or not the rotor of the stepping motor is near the mechanically stable position of the stepping motor based on the state number of If it exists, a command is output to the second drive signal generating means, and the second drive signal to which the command from the control means is input is output. Generating means outputs a drive signal for rotating the stepping motor to the next mechanical stable position in the rotation direction of the stepping motor. Therefore, the stepping motor control device of the present invention has no wasteful state when switching the stepping motor from the low-speed rotation to the high-speed rotation, and can significantly reduce the acceleration time for rotating the stepping motor at a high speed compared to the conventional art. it can.

[0015] The stepping motor control method of the present invention comprises:
First drive signal generating means for rotating the stepping motor at a low speed, second drive signal generating means for rotating the stepping motor at a high speed, and switching between the first drive signal generating means and the second drive signal generating means Control means for switching the stepping motor from low-speed rotation to high-speed rotation, wherein the control means causes the rotor of the stepping motor to rotate based on the amplitude of the drive signal output from the first drive signal generation means. Determining whether the stepping motor is located near a mechanically stable position; and, if the rotor of the stepping motor is located near a mechanically stable position, the control means causes the second drive Outputting a command to the signal generation means, and the second drive signal generation means, to which the command from the control means is input, comprises the stepping motor; And a step of outputting a driving signal for rotating the stepping motor to the next mechanical stable position in the rotation direction of the motor. Therefore, according to the stepping motor control method of the present invention, when switching the stepping motor from the low-speed rotation to the high-speed rotation, a useless state does not occur, and the acceleration time for rotating the stepping motor at a high speed is greatly reduced as compared with the related art. be able to.

According to another aspect of the present invention, there is provided a stepping motor control method comprising: first driving signal generating means for rotating a stepping motor at a low speed; second driving signal generating means for rotating the stepping motor at a high speed; And a control means for switching between the second drive signal generation means and the second drive signal generation means. When the stepping motor is switched from low-speed rotation to high-speed rotation, the control means has the first drive signal generation means. Determining whether the rotor of the stepping motor is near the mechanically stable position of the stepping motor based on the state number; and determining whether the rotor of the stepping motor is near the mechanically stable position. If the control means performs the second
Outputting a command to the drive signal generating means, and the second drive signal generating means, to which the command from the control means is input, moves the stepping motor to the next mechanical stable position in the rotation direction of the stepping motor. And outputting a drive signal for rotating. Therefore, according to the stepping motor control method of the present invention, when switching the stepping motor from the low-speed rotation to the high-speed rotation, no useless state occurs, and the stepping motor is moved to the next mechanically stable position in a shorter time than the conventional control method. The rotor of the stepping motor can be moved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a stepping motor control device and a stepping motor control method according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a block diagram showing a stepping motor control circuit according to Embodiment 1 in which the stepping motor control method of the present invention is implemented by an electric circuit. Less than,
First Embodiment A stepping motor control method according to a first embodiment of the present invention will be described with reference to FIG. In FIG. 1, a first drive signal generating means 1A generates a drive signal for rotating the stepping motor as shown in FIG. 7 at a low speed. From the first drive signal generation means 1A, a drive signal 1H for driving the coil A phase of the stepping motor and a drive signal 1J for driving the coil B phase are output. The second drive signal generating means 1B generates a drive signal for rotating the stepping motor as shown in FIG. 6 at a high speed. From the second drive signal generating means 1B, a drive signal 1K for driving the coil A phase of the stepping motor and a drive signal 1L for driving the coil B phase are output. The drive signals 1H and 1K are the first
, And the drive signals 1J and 1L are respectively input to the second switch 1D.

The control means 1E outputs a command signal 1N to the first drive signal generation means 1A, and outputs the command signal 1N to the first drive signal generation means 1A.
Change the state of A. Further, the control means 1E outputs the command signal 1P to the second drive signal generation means 1B to change the state of the second drive signal generation means 1B. Further, the control means 1E switches the first switch 1C and the second switch 1D simultaneously by the switching signal 1M. Therefore, the controller 1E selects one of the first drive signal generator 1A and the second drive signal generator 1B, and outputs the drive signals 1Q and 1R. Drive signal 1Q
And 1R are input to the first exciting means 1F and the second exciting means 1G, respectively. The first exciting means 1F and the second exciting means 1G amplify the drive signals 1Q and 1R, respectively, and output the coil A phase (1) of the stepping motor.
S) and the coil B phase (1T) are excited.

Hereinafter, the control principle of the stepping motor control method according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a characteristic diagram showing the relationship between the position of the stepping motor and the torque. 2, the horizontal axis indicates the position of the point P in FIG. 5 described above. The position 2X in FIG. 2 indicates that the point P in FIG. 5 is located at the position 5X. Similarly, the position 2W on the horizontal axis in FIG.
And 2Y indicate that point P in FIG. 5 is at position 5W and position 5Y, respectively. The vertical axis in FIG. 2 represents the torque generated in the stepping motor when the coil of the stepping motor is excited by the drive signal in the state 6Y in FIG. In FIG. 2, the torque in the positive direction on the vertical axis represents the magnitude of the torque for moving the position of the rotor on the horizontal axis to the right. Therefore, in FIG.
When a rotor is present at X, the rotor can move to position 2Y under the greatest torque. this is,
The point P in FIG. 5 receives the largest torque when it is at the position 5X, and the point P can move to the position 5Y. That is, the torque of the stepping motor for a certain drive signal is determined by the position of the rotor.

Here, in order to move the head or the like of the disk drive by rotating the stepping motor at a high speed,
More than a certain torque is required. By generating a torque that exceeds the minimum torque required for this high-speed rotation,
The rotor of the stepping motor can move from position 2X to position 2Y in FIG. In FIG. 2, the minimum torque magnitude 2T required for the rotor of the stepping motor to move is indicated by a horizontal broken line. In FIG. 2, comparing the torque generated by the stepping motor with the torque required for high-speed rotation, it is possible to generate a torque that exceeds the torque required for high-speed rotation even if the position of the rotor slightly deviates from the position 2X. That is, from position 2XA in FIG.
Within the range of XB, the rotor can move to the position 2Y at a high speed.

In the stepping motor control method of the present invention, just before performing high-speed rotation, it is determined to which position the rotor has advanced at low-speed rotation. Then, if the position of the rotor has reached the vicinity of the mechanical stable position, that is, within the range of the position 2XA to 2XB in FIG. 2, the rotor is moved to the first mechanical stable position 2X as the first drive signal of the high-speed rotation. Instead of outputting a drive signal, a drive signal for moving to the next mechanical stable position 2Y is output. As a result, the acceleration time for rotating the stepping motor at a high speed can be significantly reduced as compared with the related art.

FIG. 3 is a waveform diagram showing a drive signal switching pattern according to the first embodiment of the present invention. In FIG. 3, 3A
Represents a voltage waveform appearing between terminals of the coil A phase of the stepping motor, and 3B represents a voltage waveform appearing between terminals of the coil B phase. The drive signal switching pattern shown in FIG. 3 shows how the control of the stepping motor is switched from low-speed rotation to high-speed rotation.

The low-speed rotation portion represents the portion of the conventional drive signal pattern 2 shown in FIG. 7 which changes from the state 7W to the state 7X, and the portion which changes from the state 3W to 3X in FIG. Yes, it is. This low-speed rotation corresponds to the point P moving at a low speed from the position 5W to the position 5X in FIG. The high-speed rotation portion represents the state 6Y and the state 6Z of the conventional drive signal pattern 1 shown in FIG.
FIG. 3 corresponds to state 3Y and state 3Z.
In this high-speed rotation, the point P in FIG.
, And then to the position 5Z.

[Control Operation of Stepping Motor of First Embodiment] The stepping motor of the first embodiment of the present invention expressed as described above is shown in FIG. 1, FIG. 2, FIG. 3, and FIG.
Next, the control operation will be described with reference to FIG. In FIG. 1, the control means 1E controls a first switch 1C by a switching signal 1M.
And the second switch 1D. The control means 1E rotates the stepping motor at a low speed by selecting the drive signals 1H and 1J output from the first drive signal generation means 1A. In this state, if it is necessary to switch the stepping motor from the low-speed rotation to the high-speed rotation, the control unit 1E controls the drive signal 1H or 1J for the drive signal that is in the process of changing. And the target drive signal 1
Compare with H or 1J amplitude. This comparison level is a comparison value for determining whether or not the rotor exists within the range between the positions 2XA and 2XB in FIG. This comparison value can be determined at the design stage by a mechanical sliding load with respect to the torque of the stepping motor. Based on the result of the comparison, the control means 1E outputs the command signal 1P to the second drive signal generation means 1B, and outputs the command signal 1P to the second drive signal generation means 1B.
Determine the state of. Then, the control means 1E simultaneously switches the first switch 1C and the second switch 1D with the switching signal 1M, and selects the drive signals 1K and 1L output from the second drive signal generation means 1B.

[Switching operation of the first switch 1C and the second switch 1D] The switching operation of the first switch 1C and the second switch 1D will be described with reference to FIG. FIG.
In the low-speed rotation, the terminal voltage of the coil B phase (3B)
Is in the process of changing, but at the time of switching to high-speed rotation, the voltage has not yet completely reached the state 3X. That is, in FIG. 5 described above, point P is in the middle of performing low-speed rotation from position 5W to 5X, and point P is completely at position 5W.
X has not been reached.

In the conventional drive signal switching pattern, as shown in FIG. 9 described above, the pattern of the state 9X is output as the first drive signal in the high-speed rotation. That is, in low-speed rotation before switching to high-speed rotation, the position 5 in FIG.
If the point P has not completely reached X, the first drive signal when switching to high-speed rotation is to make the point P completely reach the position 5X in FIG. 5 and then to the position 5Y. Was rotating. On the other hand, in the first embodiment of the present invention, comparison levels 3SA and 3SB as shown in FIG. 3 are provided. By comparing the voltage between the terminals of the coil changing at low speed with the comparison level 3SA or 3SB, it is determined whether the point P in FIG. 5 exists between the position 2XA and the position 2XB in FIG. If the voltage between the terminals of the coil, which is changing at a low speed, changes from negative to positive, the voltage between the terminals of the coil is compared with the comparison level 3SA, and if the voltage between the terminals of the coil is larger than 3SA. , The point P in FIG. 5 exists between the position 2XA and the position 2XB in FIG. When the voltage between the terminals of the coil that is changing at the low speed rotation changes from positive to negative, the voltage between the terminals of the coil is compared with the comparison level 3SB, and if the terminal voltage of the coil is smaller than 3SB, The point P in FIG. 5 exists between the position 2XA and the position 2XB in FIG.

The point P in FIG. 5 is shifted from the position 2XA in FIG.
If it is present between XB, it is possible to generate the torque required to move to the next position 2Y while rotating at high speed. That is, the drive signal for completely bringing the point P in FIG. 5 to the position 5X, which is required in the related art, becomes unnecessary. Therefore, in the stepping motor control method according to the first embodiment, the first drive signal in the high-speed rotation is not the drive signal for moving to the position 5X, but the position 5Y.
Can be started from the drive signal for moving to.

In the example shown in FIG. 3, when the rotation is switched from the low speed to the high speed, the voltage between the terminals of the coil B phase (3B) is smaller than the comparison level 3SB. State 3Y can be used. The generation of the drive signal in the state 3Y is realized by the control means 1E in FIG. 1 determining the state of the second drive signal generating means 1B based on the command signal 1P.
From the above, the conventional control method shown in FIG.
In comparison with Example 1 of the present invention, which is shown in FIG. 3, the state of the control method in FIG. 3 is advanced to the next position at the same time. For this reason, the control method according to the first embodiment of the present invention can accelerate the stepping motor in a shorter time than the conventional control method.

As described above, according to the first embodiment of the present invention, when the drive signal of the stepping motor is switched from the low-speed rotation to the high-speed rotation, the amplitude of the drive signal is compared with the comparison level, so that the rotor of the stepping motor is controlled. The position can be determined, and the high-speed rotation drive signal can be started from the next state. Therefore, the stepping motor control method according to the first embodiment of the present invention can accelerate the stepping motor in a shorter time than before.

Second Embodiment Next, a stepping motor control method according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a waveform diagram showing a drive signal switching pattern in the stepping motor control method according to the second embodiment of the present invention. In the stepping motor control method according to the second embodiment, the stepping motor control circuit has substantially the same configuration as that of the stepping motor control circuit shown in FIG. 1 of the first embodiment. Will be explained. In FIG. 4, 4A indicates a voltage waveform appearing between terminals of the coil A phase of the stepping motor, and 4B indicates a voltage waveform appearing between terminals of the coil B phase. The drive signal switching pattern shown in FIG. 4 shows how the control of the stepping motor is switched from low-speed rotation to high-speed rotation. The low-speed rotation portion represents a change from the state 8W (phase number Ph00) of the conventional drive signal pattern 3 shown in FIG. 8 to the state 8X (phase number Ph08) as shown in FIG.
4X to 4X. This low-speed rotation corresponds to the point P moving at a low speed from the position 5W to the position 5X in FIG. 5 described above. The high-speed rotation portion represents the state 6Y and the state 6Z of the conventional drive signal pattern 1 shown in FIG. 6, and corresponds to the state 4Y and the state 4Z in FIG. This high-speed rotation corresponds to the point P moving to the position 5Y and then to the position 5Z in FIG.

[Control Operation of Stepping Motor of Second Embodiment] The control operation of the stepping motor according to the second embodiment of the present invention as described above will be described with reference to FIGS.
This will be described next with reference to FIGS. 4, 5, and 8. In FIG. 1, a control means 1E controls a first switch 1C and a second switch 1D by a switching signal 1M, and outputs drive signals 1H and 1H output from a first drive signal generation means 1A.
Select J. Thus, in the second embodiment, the stepping motor is rotated at a low speed. When it is necessary to switch the stepping motor from the low-speed rotation to the high-speed rotation while the stepping motor is rotating at a low speed, the control means 1E determines that the phase number of the first drive signal generating means 1A is close to the mechanically stable position. Determine if there is. The phase number allows the internal state of the first drive signal generating means 1A to be known from the command signal 1N.
Next, a method for determining whether or not the phase number is near the mechanical stable position in the control means 1E will be described.
This will be specifically described. For example, in FIG.
(Phase number Ph08) is a state in which point P in FIG. 5 is at mechanical stable position 5X. The phase number Ph0 before and after the phase number Ph08 of FIG.
In the case of 7 and Ph09, the point P in FIG. 5 is located near the mechanical stable position 5X. In other words, it can be determined from the phase number whether or not the rotor of the stepping motor exists within the range from position 2XA to position 2XB shown in FIG. Similarly, the other mechanical stable positions are in the state 8Y (phase number Ph1
Phase numbers Ph15 and Ph17 before and after one of 6)
Is near the mechanical stability position.

The correspondence between the range of positions 2XA to 2XB in FIG. 2 and the range by the phase number in FIG. 8 is determined at the design stage by the resolution of microsteps and the sliding load of the mechanical mechanism on the torque of the stepping motor. be able to. Based on the comparison of the phase numbers, the control unit 1E outputs the command signal 1P to the second drive signal generation unit 1B, and determines the state of the second drive signal generation unit 1B. Then, the control means 1E switches between the first switch 1C and the second 1D according to the switching signal 1M, and selects the drive signals 1K and 1L output from the second drive signal generating means 1B.

In the low-speed rotation shown in FIG.
Although the inter-terminal voltage (4B) of the phase is in the process of changing, it is still completely in the state 4X at the time of switching from low-speed rotation to high-speed rotation.
(Phase number Ph08) has not been reached. That is, in FIG. 5, at the point of switching from low-speed rotation to high-speed rotation, point P is in the middle of performing low-speed rotation from position 5W to position 5X, and has not completely reached position 5X. In the conventional drive signal switching pattern,
As shown in FIG. 10, the pattern of the state 10X is output as the first drive signal in the high-speed rotation. That is, if the point P shown in FIG. 5 does not completely reach the position 5X in the low-speed rotation immediately before switching to the high-speed rotation, the first drive signal of the high-speed rotation is completely shown in FIG. After the point P has reached the position 5X, the point P is then rotated toward the position 5Y.

On the other hand, in Embodiment 2 of the present invention, FIG.
When switching to high-speed rotation before reaching the state 4X (phase number Ph08) in low-speed rotation as shown in FIG. This is performed by comparing the phase numbers. Thus, it is determined whether the point P in FIG. 5 exists between the position 2XA and the position 2XB in FIG.

In the example shown in FIG. 4, the state number 4Y can be used as the first drive signal in the high-speed rotation because the phase number has advanced to Ph07 when the rotation is switched. The generation of the drive signal in the state 4Y is realized by the control means 1E in FIG. 1 determining the state of the second drive signal generating means 1B based on the command signal 1P.

From the above description, comparing the conventional stepping motor control method shown in FIG. 10 with the stepping motor control method of the second embodiment of the present invention, an example of which is shown in FIG. The state of the control method is advanced to the next position. Therefore, Embodiment 2 of the present invention
This control method allows the stepping motor to be accelerated in a shorter time than the conventional control method.

As described above, according to the second embodiment of the present invention, when the drive signal of the stepping motor is switched from the low-speed rotation to the high-speed rotation, the phase numbers of the drive signal generating means are compared, so that the rotor of the stepping motor is controlled. The position can be determined, and the high-speed rotation drive signal can be started from the next state. Therefore, according to the stepping motor control method of the second embodiment, it is possible to accelerate the stepping motor in a shorter time than in the related art.

The stepping motor control methods according to the first and second embodiments of the present invention can be configured by software instead of the electric circuit as shown in FIG. In that case, the excitation means 1F and 1F in FIG.
G, coil A phase (1S), and coil B phase (1T) are constituted by circuits, but the other components are a microcomputer or a DSP (Digital Signal Proc).
(Essor) or the like can be configured by software embedded in an arithmetic LSI. As described in the first and second embodiments of the present invention, the formation of the driving signal pattern, the comparison operation of the driving signals, the determination of the phase number, the switching processing of the driving pattern are performed by using the software means, and the final operation is performed. The resulting voltage value of the drive signal is output as a digital signal to the excitation means 1F and 1G. The excitation means 1F and 1G convert the voltage value of the digital signal into a PWM signal or a D /
The coil is excited by converting the signal into an analog signal by A-conversion or the like and amplifying the analog signal.

[0040]

As described above, according to the stepping motor control apparatus of the present invention, when the control of the stepping motor is switched from the low-speed rotation to the high-speed rotation, the amplitude of the drive signal in the low-speed rotation or the state of the drive signal generating means is provided. Based on the number, it is determined whether the rotor of the stepping motor is near the mechanical stable position of the stepping motor, and the rotor of the stepping motor is moved to the next mechanical stable position in the stepping motor rotation direction. They are being moved quickly. Therefore, according to the present invention, no wasteful state occurs when the stepping motor is switched from the low-speed rotation to the high-speed rotation, and the acceleration time for rotating the stepping motor at a high speed can be significantly reduced as compared with the related art. In the stepping motor control method of the present invention, the drive signal at the time of switching to high-speed rotation can move the rotor of the stepping motor to a mechanically stable position ahead of the conventional one in the same time. For this reason, the stepping motor control method of the present invention can accelerate the stepping motor in a shorter time than the conventional control method,
In a disk device using this stepping motor control method, the pickup can be accessed at a high speed to a target position on the disk.

[Brief description of the drawings]

FIG. 1 is a block diagram of a stepping motor control circuit according to Embodiments 1 and 2 of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a position of a stepping motor and a torque in the stepping motor control method of the present invention.

FIG. 3 is a waveform diagram showing a drive signal switching pattern according to the first embodiment of the present invention.

FIG. 4 is a waveform diagram showing a drive signal switching pattern according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a stepping motor.

FIG. 6 is a waveform diagram showing a drive signal pattern 1 (for high-speed rotation) in a conventional stepping motor control method.

FIG. 7 is a waveform diagram showing a drive signal pattern 2 (for low-speed rotation) in a conventional stepping motor control method.

FIG. 8 is a waveform diagram showing a drive signal pattern 3 (for low-speed rotation) in a conventional stepping motor control method.

FIG. 9 is a waveform diagram showing a drive signal switching pattern 1 in a conventional stepping motor control method.

FIG. 10 is a waveform diagram showing a drive signal switching pattern 2 in a conventional stepping motor control method.

[Explanation of symbols]

 1A First drive signal generation means 1B Second drive signal generation means 1C First switch 1D Second switch 1E Control means 1F First excitation means 1G Second excitation means 1S Stepping motor coil A phase 1T Stepping Motor coil B phase

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shuichi Yoshida 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] A first drive signal generating means for rotating the stepping motor at a low speed; a second drive signal generating means for rotating the stepping motor at a high speed; and the first drive signal generating means and the second drive signal. Control means for switching the generation means, wherein the control means, when switching the stepping motor from low-speed rotation to high-speed rotation, based on the amplitude of the drive signal output from the first drive signal generation means at that time It is determined whether or not the rotor of the stepping motor is located near the mechanically stable position of the stepping motor. If the rotor of the stepping motor is located near the mechanically stable position, the second step is performed. The second drive signal generation unit, which outputs a command to the drive signal generation unit and receives the command from the control unit, A stepping motor control device for outputting a drive signal for rotating the stepping motor to a next mechanically stable position in a rotation direction of the motor. 2. A first drive signal generating means for rotating the stepping motor at low speed, a second drive signal generating means for rotating the stepping motor at high speed, and the first drive signal generating means and the second drive signal Control means for switching the generation means, wherein the control means, when switching the stepping motor from low-speed rotation to high-speed rotation, based on the state number of the first drive signal generation means at that time, It is determined whether the rotor is located near the mechanically stable position of the stepping motor. If the rotor of the stepping motor is located near the mechanically stable position, the second drive signal is generated. Means for outputting a command to the means, wherein the second drive signal generating means, to which the command from the control means is inputted, is provided with a rotating direction of the stepping motor. Outputting a drive signal for rotating the stepping motor to the next mechanically stable position in the stepping motor. 3. A first drive signal generating means for rotating the stepping motor at a low speed, a second drive signal generating means for rotating the stepping motor at a high speed, and the first drive signal generating means and the second drive signal. Control means for switching the generation means, wherein when the stepping motor is switched from low-speed rotation to high-speed rotation, the control means rotates the stepping motor based on the amplitude of the drive signal output from the first drive signal generation means. Determining whether or not the rotor is near the mechanical stable position of the stepping motor; and, if the rotor of the stepping motor is near the mechanical stable position, Outputting a command to the second drive signal generation means, and the second drive signal generation means to which the command from the control means is input, Serial stepping motor control method characterized by a step of outputting a driving signal for rotating the stepping motor to the next mechanical stable position in the rotation direction of the stepping motor. 4. A first drive signal generating means for rotating the stepping motor at a low speed, a second drive signal generating means for rotating the stepping motor at a high speed, and the first drive signal generating means and the second drive signal. Control means for switching the generation means, wherein when the stepping motor is switched from low-speed rotation to high-speed rotation, the control means switches the rotor of the stepping motor based on the state number of the first drive signal generation means. Determining whether the stepping motor is located near a mechanically stable position; and if the rotor of the stepping motor is located near a mechanically stable position, the control means sets the second Outputting a command to the drive signal generating means; and receiving the command from the control means, Stepping motor control method characterized by a step of outputting a driving signal for rotating the stepping motor to the next mechanical stable position in the rotational direction of the Ngumota.