JPH06149379A - Device for moving and positioning magnetic head or the like - Google Patents

Abstract

PURPOSE:To exactly converge a rotor vibration at the center of excitation, and to correctly stop an object to be moved at a target position by applying a prescribed ratio for making the pulse interval of currents to be supplied to the before and behind phases of the stop positioning phase of a stepping motor larger than the pulse width, thereby executing a microstep excitation. CONSTITUTION:An object to be moved (magnetic head) 11 driven by a stepping motor 15 is moved to the target position. The pulse currents whose frequencies are gradually increased are supplied to the before and behind phases of the stop positioning phase of the motor 15 as the intermediate phase, and the microstep excitation is executed, so that the magnetic head can be stopped at the target position by the rotor excitation and the convergence. At that time, the prescribed ratio for making the pulse interval of the currents to be supplied to one and the other of the before and behind phases of the stepping motor 15 larger than the pulse width is applied, and the microstep excitation is executed by a driver circuit 19. Thus, the rotor vibration of the stepping motor 15 can be exactly converged at the center of excitation, and the exact positioning can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving / positioning device for a movable body driven by a stepping motor, for example, a magnetic head motor for recording information on a magnetic disk and reproducing the information. The present invention relates to a head positioning device provided in a drive mechanism.

[0002]

2. Description of the Related Art FIG. 5 is a simplified diagram showing a motor driving mechanism of a magnetic head provided in a recording / reproducing apparatus using a magnetic disk as a recording medium.

In this motor drive mechanism, the magnetic head 11
The head carriage 12 to which is fixed is guided by two parallel guide poles 13 and 14, and is driven by the stepping motor 15 to move in the left-right direction (FIG. 5).

That is, the lead screw 16 driven to rotate by the stepping motor 15 is a guide pole 1.
The lead screw 16 is extended so as to be parallel to the reference numerals 3 and 14, and an interlocking pawl 17 provided on the head carriage 12 is connected to the lead screw 16.

Therefore, when the lead screw 16 is rotationally driven by the stepping motor 15,
The interlocking pawl 17 is screw-fed, and the head carriage 12 moves in the left-right direction.

As a result, the magnetic head 11 moves in the radial direction while contacting the magnetic disk 18. The movement of the magnetic head 11 is performed with a predetermined recording track of the magnetic disk 18 as a target position, and the movement distance and stop thereof are controlled by the power supply control of the stepping motor 15.

Further, as shown in FIG. 6, power supply to the stepping motor 15 is controlled by a drive circuit 19 for bipolar driving with two-phase excitation.

That is, the drive circuit 19 receives the signal S1 which gives the number of tracks for stopping the magnetic head 11,
The signal S2 that gives the moving direction is input, and these input signals S
According to the command of 1, S2, the starter coils 20A, 2
0B is sequentially pulse-powered. Normally, the stepping motor 15 makes a basic step rotation by one pulse of a predetermined pulse.

The drive circuit 19 as described above is a means for stopping the rotor of the stepping motor 15 at a predetermined rotation angle position, that is, for accurately stopping the movement of the magnetic head 11 at the target track position. The positioning means is provided.

Although many types of positioning means have already been proposed, generally, a stepping motor is used.
The step rate of the rotor 15 is gradually lowered (the exciting current is gradually reduced), and the rotor is vibrated and converged by micro-step excitation by alternately feeding the front and rear phases of a specific phase for stopping the rotor. There are many things.

In this case, the magnetic head 11 sandwiches the target track and vibrates in small steps, and stops at the target track position due to its convergence.

[0012]

In the motor driving mechanism of the magnetic head 11 described above, a pulse current as shown in FIG. 7A is applied to the stepping motor 15 by the operation of the positioning means of the drive circuit 19. The rotor is supplied so that the rotor is vibrationally converged.

That is, this pulse current is High
The relationship between (HP) and Low (LP) is 5: 5. From this, the ratio of the pulse interval and the pulse width of the current flowing in one and the other of the front and rear phases with the front and rear phases of the positioning phase for stopping the rotor as the intermediate phase is 5: 5, and these front and rear phases are equal. Since microstep excitation is performed with the interval pulse, the vibration becomes even smaller, and even immediately before the rotor can no longer follow the vibration of the excitation phase, the vibration of FIG.
As shown in (B), the rotor vibration largely appears, and therefore, the vibration does not converge at the correct position and the rotor may stop at a position deviated from the excitation center (the center of the combined magnetic field of the front and rear phases). is there.

This stopping operation will be described with reference to the magnetic potential curve 21 shown in FIG. The rotor reaches the 21A position by the basic step, the microstep is moved from the 21A position by supplying the above-mentioned pulse current, and the rotor vibrates around the excitation center HO.

However, since the vibration width is large even at the end of vibration, it does not converge to the excitation center HO, and the rotor 21B
Stop at the position and between the excitation center HO which is the stop target
A shift of x occurs.

If the rotor of the stepping motor 15 is stopped at the displaced position as described above, the magnetic head 11 will be deviated from the target track in an unstable position.

In view of the above situation, the present invention provides a moving positioning device capable of reliably converging the rotor vibration of the stepping motor at the excitation center and correctly stopping the movable body such as the magnetic head at the target position. The purpose is to develop.

[0018]

In order to achieve the above object, according to the present invention, after moving a moving body such as a magnetic head driven by a stepping motor toward a target position, the stepping motor is rotated. -Motor stop Positioning phase is set to intermediate phase and pulse current with gradually increasing frequency is supplied to perform microstep excitation, and the moving body is stopped at the target position by the vibration of the rotor and its convergence. In a moving positioning device such as a magnetic head, microstep excitation is performed by giving a predetermined ratio that makes the pulse interval of the current supplied to one and the other of the preceding and following phases larger than the pulse width, and the rotor is vibrated and converged. We propose a moving positioning device for a magnetic head or the like, which is provided with an exciting means.

[0019]

In the moving positioning apparatus described above, the frequency of the pulse current flowing in the front and rear phases gradually increases, and the pulse current having a smaller pulse width than the pulse interval flows in one and the other of the front and rear phases. In the latter half of the vibration, the vibration becomes very small, and the rotor converges so as to fall to the excitation center with extremely small vibration.

As a result, the rotor of the stepping motor vibrates and converges, so that the movable body accurately stops at the target position.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a motor driving mechanism of a magnetic head similar to the conventional example will be described with reference to the drawings. According to the present invention, there is provided a positioning means for supplying a pulse current whose pulse width is made smaller than a pulse interval at a predetermined ratio to the front and rear phases of the stepping motor 15 to perform microstep excitation, and this positioning means is shown in FIG. It can be implemented by providing the drive circuit 19 shown in FIG.

That is, this positioning means is shown in FIG.
The stepping motor 15 is micro-step excited by the pulse current as shown in FIG.

FIG. 1A shows the pulse current of the first embodiment, where LP is "7" and HP is "3".
If the ratio between the pulse interval and the pulse width of the current flowing in the front and rear phases is set to 7: 3 in this way, the vibration width of the rotor in the latter half of the vibration is considerably reduced as shown in FIG. 1 (B).

FIG. 2A shows the pulse current of the second embodiment, where LP is "8" and HP is "2".
FIG. 2B shows the rotor vibration and its converged state when micro-step excitation is performed with such a pulse current.

FIG. 3A shows the pulse current of the third embodiment, where LP is "9" and HP is "1".
FIG. 3 (B) shows the rotor vibration and its converged state when micro-step excitation is performed with this pulse current.

As can be seen from the above-mentioned first, second and third embodiments, the vibration width in the latter half of the rotor vibration is reduced, and the effect is particularly remarkable in the third embodiment.

FIG. 4 is an explanatory view similar to FIG. 8 showing the rotor vibration when the micro step excitation is performed as described above and its converged state. As shown in the figure, the 21A position is reached by the basic step, and the micro step is started.
Repeatedly oscillates and reaches the 21B position as in the conventional example.
When the rotor reaches the position 21B, the rotor receives an extremely small vibration force and passes through 21C and converges so as to fall to the excitation center HO.

The same result as that of the above-mentioned embodiment can be confirmed as simulation data by the following formula. I (d ² θ / dt ² ) + C (dθ / dt) + K · θ = Ki · i I: Drive system inertia for rotor shaft conversion C: Damping coefficient K: Spring constant Ki: Motor torque Constant θ: angular position of rotor i: drive current

Although the embodiment of the motor drive mechanism for the magnetic head has been described above, the present invention can be similarly implemented as a device for positioning other movable bodies using a stepping motor as a drive source. The stepping motor is not limited to the two-phase excitation but may be the one-two phase excitation. In implementing the present invention, the ratio of the pulse interval to the pulse width is 73:27, 84:16 ...
It can be set in detail, such as ...

[0030]

As described above, in the positioning device according to the present invention, the rotor vibration is surely converged to the excitation center by the micro-step excitation, so that the movement of the movable body can be properly stopped at the target position. .

Further, this positioning device is a positioning device that is not significantly affected by the load, which is the object to be moved, temperature, humidity, and hysteresis.

Further, in the case where the stepping motor drive circuit is provided with a microcomputer, this positioning device can be implemented by simply changing the program thereof without requiring any other circuit configuration. This makes it a highly practical positioning device.

[Brief description of drawings]

FIG. 1A is a waveform diagram showing a pulse current according to the first embodiment. FIG. 3B shows the flow chart in the first embodiment.
It is a figure which shows the vibration of a computer and its convergence state.

FIG. 2A is a waveform diagram showing a pulse current of the second embodiment. FIG. 6B shows a flow chart in the second embodiment.
It is a figure which shows the vibration of a computer and its convergence state.

FIG. 3A is a waveform diagram showing a pulse current of the third embodiment. FIG. 6B shows the flow chart in the third embodiment.
It is a figure which shows the vibration of a computer and its convergence state.

FIG. 4 is an explanatory view showing vibration of a rotor and its converged state using a magnetic potential curve.

FIG. 5 is a simplified diagram showing a motor driving mechanism of a magnetic head provided in a magnetic disk recording / reproducing apparatus.

FIG. 6 is a simplified diagram showing a drive circuit of a stepping motor included in the motor driving mechanism of the magnetic head.

FIG. 7A is a waveform diagram showing a pulse current for microstep excitation shown as a conventional example. FIG. 6B is a diagram showing the vibration of the rotor and its converged state in this conventional example.

FIG. 8 is a conventional example of a flow chart using a magnetic potential curve.
FIG. 7 is an explanatory diagram for explaining the vibration of the oscillator and its converged state.

[Explanation of symbols]

 11 magnetic head 12 head carriage 15 stepping motor 16 lead screw 17 interlocking claw 18 magnetic disk 19 drive circuit

Claims (1)

[Claims] 1. After a movable body such as a magnetic head driven by a stepping motor is moved toward a target position, the frequency is gradually increased to a front phase and a rear phase in which a rotor stop positioning phase of the stepping motor is an intermediate phase. In a moving positioning device such as a magnetic head configured to stop a movable body at a target position by vibrating a rotor and converging it by supplying a high pulse current to the microstep excitation, Moving positioning of a magnetic head, etc., characterized in that it is provided with exciting means for microstep excitation by giving a predetermined ratio for making the pulse interval of the current supplied to the other larger than its pulse width, and for vibrating and converging the rotor. apparatus.