JPH04325899A - Drive of stepping motor - Google Patents

Abstract

PURPOSE:To get a drive of a stepping motor which can lessen the backlash without enlarging motor torque with simple constitution and is excellent in stoppage accuracy and small in noise. CONSTITUTION:When one pulse of a step signal St is input into a phase exciting circuit 2, an exciting signal Sf is output from this phase exciting circuit 2, and a stepping motor 4 rotates by the amount of one step by the exciting current for shifting it in advance direction or reverse direction by the amount of one track from a motor driving circuit 3, and a magnetic head shifts in advance direction or reverse direction by the amount of one track. When the magnetic head shifts to the desired track position, the pulse input of the step signal St ceases even if it passes the specified pulse interval, and a signal for changing the excitation for a short time over to the phase for shifting it in advance direction or reverse direction is output from a compensating excitation circuit 5 to a phase exciting circuit 2. By the excitation signal Sf from the phase exciting circuit 2, which has received this signal, a motor driving circuit 3 is energized, and the stepping motor 4 rotates a little in the advance direction, and is retained in the final position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor drive device, and more particularly, to a stepping motor drive device that can control stopping of a stepping motor in a magnetic disk device such as a flexible disk device. .

0002

2. Description of the Related Art FIG. 6 is a schematic block diagram showing a stepping motor driving device in a conventional flexible disk drive 1. In FIG. 6, reference numeral 2 indicates a step signal St from a host system and a magnetic head ( A direction signal (not shown) indicating whether the direction of travel (outer circumferential side → inner circumferential side, hereinafter referred to as CW direction) or the opposite direction (inner circumferential side → outer circumferential side, hereinafter referred to as CCW direction) A phase excitation generation circuit that outputs an excitation signal Sf receives one pulse of the step signal St and outputs an excitation signal Sf for moving the magnetic head by one track. If no pulse is output for a predetermined period of time or more, it is determined that the pulse has stopped and the excitation signal Sf in the final excitation state is output.
is output for a certain period of time.

3 is an excitation signal S from this phase excitation generation circuit.
4 is a stepping motor which is rotated by the drive current from this motor drive circuit and moves the magnetic head in steps for each track. It is.

Next, the operation of the stepping motor drive device configured as described above will be explained. First, a direction signal indicating the CW direction is output from the host system, and one pulse of the step signal St is applied to the phase excitation generation circuit 2.
, the phase excitation generating circuit 2 outputs an excitation signal Sf for moving the magnetic head by one track in the advancing direction. Upon receiving this excitation signal Sf, the motor drive circuit 3 supplies an excitation current to the determined excitation phase of the stepping motor 4 to move the magnetic head by one track in the advancing direction.

The stepping motor 4, in which the excitation current is applied to the determined excitation phase, rotates by one step and moves the magnetic head by one track in the advancing direction. Subsequently, when one pulse of the step signal St is input to the phase excitation generation circuit 2 after a predetermined time, the excitation signal Sf is output from the phase excitation generation circuit 2 and the excitation current is output from the motor drive circuit 3 in the same manner as above. The stepping motor 4 rotates by one step, and the magnetic head is moved by one track in the advancing direction.

As long as the step signal St from the host system is output at a predetermined pulse interval, the above operation is repeated, and when the magnetic head moves to a desired track position, the step signal St is output even after the predetermined pulse interval. Since the pulse input of St is no longer input, the phase excitation generation circuit 2
Here, an excitation signal Sf in the final excitation state is output for a certain period of time, and an excitation current in the final excitation state is passed from the motor drive circuit 3 for a certain period of time to maintain the rotation of the stepping motor 4 at the final state position. It is.

Furthermore, when a direction signal indicating the CCW direction is output from the host system, the magnetic head operates in the same manner as in the CW direction described above based on the step signal St, and moves the magnetic head in the reverse direction in steps for each track. When the step signal St is no longer input, the stepping motor 4 is held in the final excitation state for a certain period of time, and the rotation of the stepping motor 4 is stopped.

However, in the stepping motor drive device configured in this way, the stepping motor 4
The holding state in the stopped state is as shown in FIG. This FIG. 7 shows the relationship between the rotation angle θ of the stepping motor 4 and the motor torque T. When the motor torque T is equal to or less than T1 (corresponding to the load torque applied to the stepping motor 4), the rotation of the stepping motor 4 is This indicates that it has stopped and entered a holding state.

As is clear from FIG. 7, the stepping motor 4 will stop within the range of rotation angles from -Δθ to Δθ, resulting in a maximum backlash of 2Δθ. If this backlash is large, it is impossible to stop with high precision.In order to reduce the backlash without changing the load torque applied to the stepping motor 4, the rotor rotation angle in the excitation state at the time of stopping must be However, in this case, the motor torque during normal rotation also increases, resulting in problems such as increased vibration and noise.

[0010] Conventionally, as a method for performing a stopping operation in a stepping motor drive device in consideration of such problems, for example, when stopping, excitation of a phase in the advancing direction and a phase in the opposite direction is superimposed on the excitation of the stop phase. JP-A No. 62-48293 discloses a method in which the steps are repeated alternately multiple times, and
Japanese Patent Laid-Open No. 171498/1983 describes a method in which a stop pulse having a voltage higher than the driving voltage at the time of stop is added to the stop phase excitation at the time of stop, and furthermore, one-phase excitation and two-phase excitation are described. In the 1-2 phase excitation system that repeats alternately, the one in which the excitation state immediately before stopping is one-phase excitation is disclosed in Japanese Patent Application Laid-open No. 6.
3-148898, respectively.

[0011]

[Problems to be Solved by the Invention] However, in the above-mentioned proposals, for example,
The controls shown in JP-A No. 293 and JP-A No. 63-148898 have complicated control and complicated configurations, and the ones shown in JP-A No. 62-171498 In this case, a problem arises in that a voltage higher than the drive voltage applied to the excitation phase of the stepping motor 4 is applied, causing noise and the like.

The present invention has been made in view of the above points, and provides a stepping motor drive device that has a simple structure, can reduce backlash without increasing motor torque, has good stopping accuracy, and has low noise. The purpose is to obtain.

[0013]

[Means for Solving the Problems] In the stepping motor drive device according to the present invention, when stopping the drive in the forward direction, there is either a phase in which excitation in a stopped state is moved in the forward direction or a phase in which it is moved in the opposite direction. Compensation that switches the excitation for a short time to the phase of , and when stopping driving in the opposite direction, switches the excitation for a short time to either the phase that moves the excitation in the stopped state to the phase that moves in the opposite direction or the phase that moves in the forward direction. It is equipped with an excitation circuit.

[0014]

[Operation] In this invention, when stopping the drive in the forward direction, the compensation excitation circuit short-circuits the excitation in the stopped state to either the phase to move in the forward direction or the phase to move in the opposite direction. When switching the time excitation and stopping driving in the opposite direction, the excitation in the stopped state is switched for a short time to either the phase that moves the excitation in the reverse direction or the phase that moves the stepping motor in the forward direction, and the stepping motor stops. The rotation angle in the held state is made smaller.

[0015]

【Example】

Example 1. Embodiment 1 of the present invention is shown in FIG. 1, and the same reference numerals as in the conventional example shown in FIG. 6 indicate the same or corresponding parts. In FIG. Step signal St and CW direction or CC
When receiving a direction signal indicating whether the drive is in the W direction and stopping driving in the CW direction, that is, when the pulse of the step signal St is not input for a predetermined period of time or more, a short period of time is applied to the phase that moves the excitation in the stopped state in the CW direction. When switching the excitation and stopping driving in the CCW direction, that is, when the pulse of the step signal St is not input for a predetermined period of time or more, the excitation is switched for a short time to a phase that moves the stopped excitation in the CCW direction. This is a compensation excitation circuit that outputs a signal to the phase excitation generation circuit 2.

Next, the operation of the stepping motor drive device constructed in this manner will be explained. First, a direction signal indicating the CW direction is output from the host system, and one pulse of the step signal St is applied to the phase excitation generation circuit 2.
, the phase excitation generating circuit 2 outputs an excitation signal Sf for moving the magnetic head by one track in the advancing direction. Upon receiving this excitation signal Sf, the motor drive circuit 3 supplies an excitation current to the determined excitation phase of the stepping motor 4 to move the magnetic head by one track in the advancing direction.

The stepping motor 4, in which the excitation current is applied to the determined excitation phase, rotates by one step and moves the magnetic head by one track in the advancing direction. Subsequently, when one pulse of the step signal St is input to the phase excitation generation circuit 2 after a predetermined time, the excitation signal Sf is output from the phase excitation generation circuit 2 and the excitation current is output from the motor drive circuit 3 in the same manner as above. The stepping motor 4 rotates by one step, and the magnetic head is moved by one track in the advancing direction.

The above operation is repeated as long as the step signal St from the host system is output at predetermined pulse intervals. Note that while the step signal St consisting of a predetermined pulse interval is input to the compensation excitation circuit 5,
Since no signal is output to the phase excitation generation circuit 2, the phase excitation generation circuit 2 is not affected by the excitation signal S.
This outputs f.

When the magnetic head moves to a desired track position, the pulse input of the step signal St is no longer input even after a predetermined pulse interval, so the compensating excitation circuit 5 applies short-time excitation to the phase to be moved in the CW direction. A signal for switching is output to the phase excitation generation circuit 2. Upon receiving this signal, the phase excitation generation circuit 2 outputs an excitation signal Sf for moving the stepping motor 4 in the CW direction to the motor drive circuit 3 for a short time, that is, for a time shorter than the pulse interval of the step signal St. Rotate slightly in the direction of travel. After a short period of time has elapsed, the phase excitation generation circuit 2 outputs the excitation signal Sf in the final excitation state, and the motor drive circuit 3 causes the excitation current in the final excitation state to flow for a certain period of time to control the rotation of the stepping motor 4 to the final state. It is held in place.

Furthermore, when a direction signal indicating the CCW direction is output from the host system, the magnetic head operates in the same manner as in the CW direction described above based on the step signal St, and moves the magnetic head in the reverse direction in steps for each track. When the step signal St is no longer input, the compensating excitation circuit 5 outputs a signal for switching the excitation for a short time to the phase to be moved in the CCW direction to the phase excitation generation circuit 2, and the phase excitation generation circuit 2 is activated in the CCW direction. After outputting an excitation signal Sf for a short period of time to cause the stepping motor 4 to rotate slightly in the opposite direction for a short period of time, the stepping motor 4 is held in the final excitation state for a certain period of time and the rotation of the stepping motor 4 is stopped.

In the stepping motor drive device configured as described above, the relationship between the rotation angle θ of the stepping motor 4 in the holding state and the motor torque T when the stepping motor 4 is in the stopped state is as shown in FIG. Since the natural frequency etc. of the motor control system are fixed, when the stepping motor 4 stops rotating in the forward direction, it moves to the -△θ side as shown at point a in the figure, and vice versa. When stopping the rotation in the forward direction, the stop position usually varies to the △θ side as shown at point b in the figure, but when the stepping motor 4 stops rotating in the forward direction by the compensation excitation circuit 5 Since the stepping motor 4 is rotated in the forward direction for a short time and then stopped, and when the stepping motor 4 stops rotating in the opposite direction, it is rotated in the opposite direction for a short time and then stopped, so the rotation angle of the stepping motor 4 in the stopped state is is close to 0, the backlash is smaller than 2Δθ, and accurate stopping can be performed.

Example 2. In the stepping motor driving device, as shown in FIG. 3, when the stepping motor 4 stops rotating in the forward direction, it stops rotating in the opposite direction at a position on the △θ side as shown at point a in the figure. In some cases, the stop position varies on the -△θ side, as shown at point b in the figure. In this case, when the stepping motor 4 stops rotating in the forward direction, the compensation excitation circuit 5 causes the stepping motor 4 to rotate in the opposite direction for a short time and then stops, and when the stepping motor 4 stops rotating in the reverse direction, the stepping motor 4 stops rotating for a short time. Alternatively, a signal may be outputted from the compensation excitation circuit 5 to the phase excitation generation circuit 2 so as to rotate the rotation in the direction and then stop the rotation.

Example 3. In the stepping motor driving device, as shown in Fig. 4, when the stepping motor 4 stops rotating in the forward direction, it stops rotating in the opposite direction at a position on the -△θ side as shown at point a in the figure. In some cases, the stopping position may vary on the -Δθ side as shown at point b in the figure. In this case, when the stepping motor 4 stops rotating in the forward direction, the compensation excitation circuit 5 causes the stepping motor 4 to rotate in the forward direction for a short time and then stops, and when the stepping motor 4 stops rotating in the opposite direction, the stepping motor 4 rotates in the forward direction for a short time and then stops. The compensation excitation circuit 5 is configured to stop the rotation after rotating in the direction.
Alternatively, a signal may be output from the phase excitation generating circuit 2 to the phase excitation generating circuit 2.

Example 4. In the stepping motor field drive device, as shown in FIG. 5, when the stepping motor 4 stops rotating in the forward direction, it stops rotating in the opposite direction at a position on the △θ side as shown at point a in the figure. When is illustrated b
As shown by the dots, there are some cases in which the stop position varies on the Δθ side. In this case, when the stepping motor 4 stops rotating in the forward direction, the compensation excitation circuit 5 causes the stepping motor 4 to rotate in the opposite direction for a short time and then stops, and when the stepping motor 4 stops rotating in the opposite direction, the stepping motor 4 rotates in the opposite direction for a short time and then stops. Alternatively, a signal may be outputted from the compensation excitation circuit 5 to the phase excitation generation circuit 2 so as to rotate the rotation in the direction and then stop the rotation.

Example 5. In Examples 1 to 4 above,
When the compensation excitation circuit 5 stops depending on whether the direction signal from the host system is in the forward or reverse direction, the stepping motor 4 is slightly rotated in the forward direction or in the reverse direction for a short time.
The compensation excitation circuit 5 may output a signal to the phase excitation generation circuit 2 for excitation in the forward direction or in the opposite direction depending on whether the rotation angle is on the -△θ side or the △θ side. It is something.

[0026]

Effects of the Invention As described above, when stopping the drive in the forward direction, the excitation in the stopped state is shortened to either the phase of moving in the forward direction or the phase of moving in the opposite direction. A compensation excitation circuit is provided that switches the excitation for a short period of time and, when stopping the drive in the opposite direction, switches the excitation in the stopped state to either the phase that moves the excitation in the opposite direction or the phase that moves it in the forward direction. Therefore, the rotation angle of the stepping motor in the stopped state and the held state can be reduced, backlash is reduced, and accurate stopping can be achieved with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the rotation angle and motor torque when the stepping motor 4 is in a stopped state in the first embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the rotation angle and motor torque when the stepping motor 4 is in a stopped state in a second embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the rotation angle and motor torque in a stopped state of the stepping motor 4 in Embodiment 3 of the present invention.

FIG. 5 is a diagram showing the relationship between the rotation angle and motor torque when the stepping motor 4 is in a stopped state in Embodiment 4 of the present invention.

FIG. 6 is a schematic configuration diagram showing a conventional stepping motor drive device.

FIG. 7 is a diagram showing the relationship between the rotation angle and motor torque when the stepping motor 4 is stopped in a conventional stepping motor.

[Explanation of symbols]

1 Flexible disk device 2 Phase excitation generation circuit 3 Motor drive circuit 4 Stepping motor 5 Compensation excitation circuit

Claims (1)

[Claims] Claim 1: In a stepper motor that receives a step signal and drives a stepping motor in accordance with the input step signal, when stopping the drive in the forward direction, a phase or reverse phase is used to move the excitation in the stopped state in the forward direction. Switch the excitation for a short time to either phase of the phase to be moved in the direction,
Further, when stopping the drive in the reverse direction, a compensating excitation circuit is provided that switches the excitation in the stopped state to either the phase for moving in the reverse direction or the phase for moving in the advancing direction for a short time. Stepping motor drive device.