JPH04344194A - Drive controller of stepping motor - Google Patents

Abstract

PURPOSE:To obtain a stepping motor drive controller with small seek noise. CONSTITUTION:A signal to be supplied to the first and second excitation phases of a stepping motor is monitored by EX-OR circuit 1 and D-type flip-flop 3 is driven via monostable multivibrator circuit 2 for sending an output signal for a period longer than the OFF-track time at the time of high-speed operation of the EX-OR circuit 1 and shorter than the OFF-track time at the time of low speed operation so that the time is judged to be that of the low speed operation. Then, a voltage to be supplied to the stepping motor is lowered at the time of both low speed operation and ON-track.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor drive control device used for driving a head of a magnetic disk.

0002

[Prior Art] As is well known, a step motor rotates in steps by a predetermined angle when an input signal is supplied.
Although there is an angular error of about 3% per step, the angular error does not accumulate over multiple steps, so this property is widely used to control the head positioning of floppy disk drives or magnetic disk drives. .

FIG. 4 is a circuit diagram showing an example of a two-phase excitation type drive circuit for a four-phase step motor conventionally used to drive a magnetic disk head. When the control IC 10 is supplied with direction information, step pulses, and drive select signals from a host system (not shown), it generates four types of excitation signals, from a first excitation signal PH1 to a fourth excitation signal PH4, which are out of phase with each other. . By combining these excitation signals PH1 to PH4, four types of excitation phases are created, and the first to fourth excitation phases are sequentially repeated. Each excitation signal is sent to the step motor 12 via the driver IC 11.
is supplied to each of the excitation coils 121 to 124 to rotate the step motor 12. Note that each step pulse moves the head by one track, and here the excitation phase of the step motor is switched twice for this purpose.

On the other hand, regarding the moving speed of the head, a method has been adopted in which the head is appropriately switched between high-speed movement and low-speed movement for the purpose of shortening the access time. FIG. 5 is a waveform diagram of various parts in a high-speed operation state in which the head is moved all at once to a target track, and FIG. 6 is a waveform diagram of various parts in a low-speed operation state in which tracks are sequentially read and written. In both high-speed control and low-speed control, the head is in an on-track state during the first and third excitation phases, and is in an off-track state (track and track) during the second and fourth excitation phases. The head is positioned between the Therefore, each time the excitation phase is switched twice, the head moves by one track.

In the case of high speed shown in FIG. 5, the on-track state is achieved by switching from the second excitation phase to the third excitation phase or from the fourth excitation phase to the first excitation phase at the timing t=tf, and in the case of low speed, the on-track state is established. Similarly, the on-track state is switched to the on-track state at the timing of =ts.

Table 1 shows the relationship between the state of each excitation signal and the moving direction of the rotor in four different excitation phases.

[0007]

[Table 1]

[0008]

[Problems to be Solved by the Invention] The above-mentioned driving method is
This is effective in reducing seek noise that occurs when the step motor is driven. In particular, it is preferable to set the switching timing of the excitation phase to the midpoint of the step pulse. Therefore, tf and ts indicating the switching timing at high speed and low speed are different. However, even in such a driving method, due to the characteristics of the step motor, maximum torque is generated when the rotor finishes rotating, and this torque may become excessive torque and cause vibration. This vibration increases the natural frequency of the rotor and the driving frequency (
A resonance phenomenon occurs in synchronization with the step pulse frequency). This is transmitted to the head positioning mechanism, so
Even with this drive method, it was not possible to completely suppress the occurrence of seek noise.

[0009]

[Means for Solving the Problems] In order to solve such problems, the step motor drive control device of the present invention includes a step motor drive control device that determines whether or not the excitation phase of the step motor corresponds to the stop position of the driven body. 1 determining means, and a 2nd determining means for determining whether the driving speed of the step motor is high speed or low speed.
A signal indicating that the excitation phase corresponds to a stop position of the driven body is inputted from the determining means and the first determining means, and a signal indicating that the driving speed of the step motor is low is inputted from the second determining means. Sometimes, the step motor drive means is provided with a step motor drive means for lowering the drive voltage of the step motor lower than the steady voltage.

0010

[Operation] When the driven body is moved at low speed to reach an arbitrary stop position, the step motor drive means sets the drive voltage of the step motor lower than the steady voltage. When exciting the step motor in other conditions, that is, when moving the driven object at high speed or between a stop position and another stop position at low speed, the drive voltage should be a steady voltage. .

[0011]

[Embodiment] FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention. A drive select signal, a step signal, and a direction signal are supplied from a circuit (not shown) to a control IC 10, which will be described later. By generating four types of signals from the first excitation signal PH1 to the fourth excitation signal PH4 having a phase relationship of 12
is set to rotate.

[0012] First excitation signal PH1, second excitation signal PH2
is input to the EX-OR circuit 1, and the EX-OR circuit 1
The output signal is supplied to the mono multi-circuit 2, the D input terminal of the D-type flip-flop 3, and one input of the NOR circuit 4, respectively. The output of the monomulti circuit 1 is supplied to the clock terminal C of the flip-flop 3, and the Q-bar output of the flip-flop 3 is supplied to the other input of the NOR circuit 4.

The output of the NOR circuit 4 is supplied to the base of a transistor 6 via a resistor 5, and the transistor 6 is controlled to be turned on and off by the signal supplied from the NOR circuit 4, and when the transistor 6 is on, The power supply voltage VCC is supplied almost as is to the step motor 12, and when the transistor 6 is off, the power supply voltage VCC is supplied to the step motor 12 via the resistor 7, so a low voltage is supplied at this time. There is. Note that a resistor 8 is connected between the base and emitter of the transistor 6, and a capacitor 9 is connected between the base and collector.

Waveforms of various parts of the circuit configured as described above are shown in FIGS. 2 and 3, and FIG. 2 shows the operating waveforms during high-speed operation,
FIG. 3 shows operating waveforms during low-speed operation.

[0015] During both high-speed operation and low-speed operation, four excitation states from the first excitation phase to the fourth excitation phase are repeated. In the high speed case shown in Figure 2, the second
The on-track state is achieved by switching from the excitation phase to the third excitation phase and from the fourth excitation phase to the first excitation phase, and in the case of low speed shown in Fig. 3, the on-track state is similarly switched at the timing of t=ts. ing. That is, both at high speed and at low speed, the first excitation phase and the third excitation phase are on-track excitation states.

The EX-OR circuit 1 constitutes a first determination circuit that determines whether the excitation state is on-track or off-track. That is, if both inputs do not match, an H level signal is output to indicate that the excitation state is in an off-track state, and if both inputs match, an L level signal is output. This shows that the excitation state is on track.

The monomulti circuit 2 is configured to be triggered by the rising edge of this signal, and its operating time t
os is set to tf<tos<ts. Moreover, this mono multi-circuit 2 is L during the set time tos.
It is configured to output a level signal. Since the output signal of the mono multi-circuit 2 is supplied as a clock signal to the flip-flop 3, E
The output signal of the X-OR circuit 1 is latched into the flip-flop 3.

In the case of FIG. 2, which is an example of high-speed operation, the operating time tos of the monomulti circuit 2 is set longer than the time during which the EX-OR circuit 1 outputs an H level signal. Therefore, the output of the mono multi circuit 2 rises after the output of the EX-OR circuit 1 becomes L level, so that the Q bar output of the flip-flop 3 outputs an H level signal. On the other hand, in the case of FIG. 3, which is an example of low-speed operation, the operating time tos of the monomulti circuit 2 is set shorter than the time during which the EX-OR circuit 1 outputs a 1-level signal. Therefore, while the output of EX-OR circuit 1 is at H level, the output of mono multi circuit 2 rises, so flip-flop 3 is at L level.
Outputs a level signal.

From this, the EX-OR circuit 1, the mono-multi circuit 2, and the flip-flop 3 constitute a second determination circuit that determines whether the circuit is in a low-speed operation state or a high-speed operation state.

During high-speed operation, as described above, when the output of the monomulti circuit 2 rises, the D input terminal is at the L level, so the output of the flip-flop 3 outputs a signal at the H level. This state continues until the mono multi-circuit 2 rises next time, and even then, the flip-flop 3 remains high.
Since the flip-flop 3 sends out a high-level signal, it always sends out a high-level signal during high-speed operation.

Therefore, during high-speed operation, the NOR circuit 4 is always off and transmits an L level signal, so the transistor 6 is always on. This means that the step motor 12 is always driven by the power supply voltage VCC.

On the other hand, during low-speed operation, when the output of the mono multi-circuit 2 rises as described above, the D input terminal is at the H level, so the Q bar output of the flip-flop 3 is at the L level.
It outputs a level signal. This state continues until the mono multi-circuit 2 starts up next time, and even then, the flip-flop 3 sends out an L-level signal, so the flip-flop 3 always sends out an L-level signal during low-speed operation.

Therefore, during low-speed operation, the NOR circuit 4
The signal shown in FIG. 3(i), which is controlled by the output level of the OR circuit 1, is output. When the output of the NOR circuit 4 is at H level, the transistor 6 is turned off, and a low voltage is applied to the step motor 1.
2. That is, during the on-track period, a low voltage is supplied to the step motor 12.

For this reason, the step motor 12 operates at a low voltage at low speed and on-track. Therefore, the torque is reduced and seek noise is reduced.

[0025] Although the above embodiments have been explained with respect to the control of the head, other methods such as an X-Y stage, a robot,
It can also be applied to other positioning devices.

[0026]

As described above, the present invention has the effect that seek noise can be reduced because the voltage supplied to the step motor is lowered during low-speed operation and on-track. Furthermore, since the vibration of the head can be reduced, the head can be set on the track in a short time, resulting in faster reading and writing of information. Furthermore, compared to conventional methods that operate at a constant voltage, current consumption can be reduced by the amount of voltage reduction.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention.

[Figure 2]
Waveform diagram of each part of the device in Figure 1 during high-speed operation

[Figure 3] Waveform diagram of each part of the device in Figure 1 during low-speed operation

[Fig. 4] Circuit diagram showing the configuration of an example of a conventional device

[Figure 5] Waveform diagram of each part of the device in Figure 4 during high-speed operation

[Figure 6] Waveform diagram of each part of the device in Figure 4 during low-speed operation

[Explanation of symbols]

1...EX-OR circuit 2...Mono multi circuit 3...Flip-flop 4...NOR circuit 5, 7, 8...Resistance 6...Transistor 10...Control IC 11...Driver IC 12...Step motor

Claims (2)

[Claims] Claim 1: In a step motor drive control device that achieves one step movement of a driven body by switching the excitation phase multiple times, whether or not the excitation phase of the step motor corresponds to the stop position of the driven body. a first discriminating means for discriminating;
A second determining means for determining whether the drive speed of the step motor is high or low, and a signal indicating that the excitation phase corresponds to the stop position of the driven body are input from the first determining means; A step motor comprising: step motor drive means that lowers the drive voltage of the step motor below a steady voltage when a signal indicating that the drive speed of the step motor is low is input from the determination means. drive control device. 2. The driven object is a head of a magnetic disk,
2. The step motor drive control device according to claim 1, wherein the stop position is on a track of the magnetic disk.