JPH063669B2 - Magnetic head loading method - Google Patents

Description

(A) Technical Field of the Invention The present invention relates to a magnetic head loading method for a magnetic disk device, and more particularly, to loading a movable magnetic head during use,
The present invention relates to a loading method of a magnetic head that works to unload when stopped.

(b) Conventional technology and problems Currently, as a loading method of a magnetic head of a magnetic disk device, a contact start / stop method (C
The system called SS system) is the mainstream. This literally means that when the rotation of the disk-shaped recording medium (hereinafter abbreviated as "disk medium") is stopped, that is, when writing or reading of information is not performed, the magnetic head is brought into close contact with the disk medium to perform the writing or reading operation. At the same time, the disk is rotated, and the air flow accompanying the rotation causes the magnetic head to levitate a minute gap to write and read information to and from the disk medium, and when the rotation is stopped, the magnetic head is brought into close contact with the disk medium again.

This method has the advantage of not requiring a mechanism for loading, but on the other hand, since the disk medium and the magnetic head slide at a fairly high speed at the start of rotation and immediately before the stop of rotation, they wear or attract each other. Trouble is likely to occur. Therefore, in order to prevent the above-mentioned troubles, it is necessary to take wear resistance on the disk medium and the magnetic head and to apply a lubricating oil to the disk surface. In particular, in recent high-density discs, since thinned discs are used, the film strength is not always sufficient, and the conventional loading method has a drawback that long-term reliability of the thinned disc is not always sufficient. there were.

(c) Object of the invention The present invention was devised in view of the above-mentioned drawbacks of the conventional magnetic head loading method. When the writing or reading of information is stopped, the disk medium and the magnetic head are placed in a completely non-contact state. , The function of quickly loading the magnetic head to a predetermined flying height after the start of rotation is carried out without a complicated mechanism, and the wear caused by the sliding of the disk medium and the magnetic head,
It is to provide a loading method of a magnetic head that prevents adsorption.

(d) Structure of the Invention According to the present invention, a negative pressure slider which has a magnetic head therein and draws the magnetic head to a predetermined height on a disk-shaped recording medium by negative pressure, and the negative pressure slider at one end A gimbal that supports the head arm, a head arm that fixes the other end of the gimbal, an actuator that moves the head arm, and a control circuit that drives the actuator to place the magnetic head at a predetermined position on the disk-shaped recording medium. And a means for vibrating the actuator in the seek direction near the natural frequency of the slider and the gimbal system in the magnetic head moving device. The slider and gimbal system are provided by activating the vibrating means when the recording medium reaches a predetermined number of revolutions. Vibration was achieved by loading system of a magnetic head, characterized in that to load the magnetic head to the retracted height.

(e) Embodiment of the Invention An embodiment of the magnetic head loading method according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic perspective view of a negative pressure slider to which this embodiment is applied. In the figure, a slider 4 includes a positive pressure generating portion 41 called a side rail, a cross rail 42, and a negative pressure generating portion that generates a negative pressure that acts to attract the magnetic head 45 to a disk medium in a region behind the cross rail 42. It consists of 43 and. As shown in FIG. 2, the slider 4 is attached to the head arm 2 via the gimbal 3 composed of a soft leaf spring at a height of h0 from the disk medium 1 and seeks in the direction of arrow a in the figure.

FIG. 3 is a view of the slider shown in FIG. 2 as viewed in the direction of arrow A. The slider 4 is obliquely attached to the surface of the disk medium at an angle of δ. This is to generate more negative pressure in the negative pressure generating unit 43 than when it is retracted, and by setting this angle, the retracted height h1 can be made larger. Further, once loaded, the slider posture becomes a stable posture substantially parallel to the disk surface due to self-stability, as shown by the broken line in the figure. It should be noted that arrow B in the figure indicates the direction of air flow that occurs as the disk medium 1 rotates.

In the present invention, the arrow a is preceded by the normal seek operation.
The slider 4 is vibrated at a specific frequency in the seek direction to load the slider at the position indicated by the broken line. The operation at this time will be described with reference to the characteristic diagram showing the self-attracting property of the negative pressure slider in FIG.

That is, in the figure, the solid line F1 shows the positive pressure, the broken line F2 shows the negative pressure, and the alternate long and short dash line F3 shows the spring force. Then, the positive pressure is almost zero, and if the negative pressure is larger than the soft spring force, it is loaded, but the height h1 at this time is generally as small as several tens of μm. It is difficult for general equipment to be loaded only by ensuring the dimensions and accuracy of the above mechanism. Therefore, as shown in the relationship diagram between the peripheral speed of the disk and the flying height of the slider in all the operations from unloading to loading of the magnetic head shown in FIG. 5, the mounting height (initial height) h0 of the slider 4 and the pull-in height are set. In the present invention, the height h1 is compensated by the forced excitation force. In the figure, the magnetic head is loaded →→→ after rotation is disclosed, and information is written / read at. on the other hand,
When the rotation is stopped, the disk moves as the disk decelerates, and unloading is performed naturally at the point (Vs) when the spring force exceeds the negative pressure, and the height h0 at the time of stop is restored.

FIG. 6 is a characteristic diagram of experimental values of the frequency characteristic of the transfer function of the on-arm acceleration to the slider tip acceleration when the gimbal system is vertically vibrated.

The frequency ω0 is a natural frequency due to the mass m of the slider 4 and the rigidity k of the leaf spring 3, and ω0 = (1 / 2π) , Which is a low frequency of about several tens Hz to 100 Hz in general. At this resonance, since the gimbal 3 is a metal leaf spring, the damping is very small. Therefore, the peak gain A0 is quite large, reaching 30db to 40db.

FIG. 7 is a transfer function diagram of horizontal acceleration vs. vertical acceleration when the actuator that vibrates the head arm 2 is vibrated in the seek direction. Ideally, it is 0, but in reality, due to various vibration factors. It is not 0 and has a gain A1.

From FIG. 6 and FIG. 7, the load is established if the amplitude given by A = (h0−h1) / (A0 × A1) (1) is given to the actuator. Even if an ideal actuator exists and A1 = 0, the inertial force acting on the mass of the slider 4 can be reduced by giving an initial setting angle θ to the gimbal 3 made of a leaf spring as shown in FIG. By applying the amplitude of A ≧ (h0−L1) / (Sin θ × A0) (2) by the component force, the load is established again. At this time, to show an example of actual numerical values, h0 = 0.2 mm, h1 = 0.05 m
When m, A0 = 34db (50 times), θ = 5 °, and ω0 = 100Hz, A ≧ 0.034mm (in the case of sine wave), and the acceleration Aω ² ≈1.4G at this time. This is also almost equivalent when A1 = -22db in the above equation (1). In any case, it can be seen that a vibration with a considerably small amplitude is sufficient, and that a small acceleration of several tenths during actual seek or acceleration is also sufficient during acceleration.

To summarize the above, θ = 0 may be set for an actuator having a large vertical acceleration, and loading can be performed by giving an angle θ for an actuator having a small acceleration.

In addition, since the resonance is used, the posture of the slider may be disturbed during transients, and there is a risk of partial contact with the disk medium.However, in reality, when the pull-in height is h1 or less, a suction force suddenly acts, and this suction force is Since it acts almost at the center of the slider, the posture self-stability is extremely good, and since the positive pressure in the low flying region is large, such a possibility is small. Once in the region of aerodynamic force below h1, the air film rigidity is so large that it is incomparable to that of a leaf spring, so that the resonance is almost suppressed and there is almost no adverse effect on the seek operation thereafter.

Next, FIG. 8 shows a block diagram of the actuator control circuit of the present invention.

In the figure, a normal actuator control section 25 feeds back a position signal from the servo demodulation circuit 24 and instructs the power amplifier 22 on the current value to be passed through the actuator 21.
The control system 26 for loading according to the present invention is controlled by a timer together with the actuator control unit 25. The switching means 23 is composed of, for example, an analog switch.

FIG. 9 is a block diagram showing an example of the configuration of the loading control system 26, which includes a noise source 31, a voltage amplifier 32 for amplifying a noise signal from the noise source 31, and the natural frequency ω.
The band pass filter 33 is set to 0, and peak noise near the resonance point of the gimbal system is generated and applied to the power amplifier 22. The reason why the peak noise is used instead of the sine wave is that the resonance point of the gimbal system may have a variation in the frequency ω0 corresponding to the resonance point due to dimensional tolerance and the like. Of course, this part may be a swept sine wave oscillator or the like with a limited frequency band.

Next, the loading control operation will be described with reference to the diagram of the control sequence in FIG. 10 showing the change in the number of revolutions after the disc medium starts to rotate.

That is, the peak noise signal is applied to the actuator at the time t0 when the number of rotations reaches f1 after the start of rotation, whereby the actuator is vibrated to load the magnetic head. Then, after the time point t1 when the rated speed f0 is reached, the switch
23 is automatically switched to the actuator control unit 25 side, and thereafter, the operation is performed in the same manner as a normal disk device.

Since the control operation described above operates completely in an open loop, the position where the slider is vibrated tends to be indefinite, but in reality, the pulling force of the attached cable, etc., causes the slider to move to the inner and outer sides of the disk. In either case, by applying a slight offset to the signal, the signal can be moved to a stopper position provided so as to represent the inner and outer peripheral ends and vibrated. Further, since the moving acceleration of the slider is low, even if it collides with the stopper, there is no particular adverse effect.

(f) Effects of the Invention As is apparent from the above description, according to the present invention, the magnetic head can be loaded and unloaded by a simple mechanism, so that wear and damage of the disk medium and the magnetic head can be avoided. It is possible to realize a magnetic disk device having a long life and high reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic structure of a negative pressure slider to which the present invention is applied, FIG. 2 is a view for explaining an embodiment of the present invention, FIG. 3 is a left side view of FIG. FIG. 4 is a characteristic diagram for explaining the self-attracting property of the negative pressure slider, and FIG. 5 is a diagram showing the relationship between the peripheral speed of the disk medium and the flying height of the head in all operations from unloading to loading of the magnetic head. 6 is a characteristic diagram based on an experimental value of a frequency characteristic of a transfer function of the acceleration on the arm versus the slider tip acceleration when the gimbal system is vertically vibrated, and FIG. 7 is a seek diagram of an actuator for exciting the head arm. Transfer function diagram of horizontal acceleration vs. vertical acceleration when excited in the direction, FIG. 8 is a block diagram of an actuator control circuit according to the present invention, FIG. 9 is an example configuration diagram of a disk control system, and FIG. Control sequence of control system Description is a diagram for. In the figure, 1 is a disk medium, 2 is a head arm, 21
Is an actuator, 22 is a power amplifier, 23 is a switching means, 24 is a servo demodulation circuit, 25 is an actuator control unit,
26 is a control system, 3 is a gimbal, 31 is a noise source, 32 is a voltage amplifier, 33 is a bandpass filter, 4 is a slider, 41 is a positive pressure generation unit, 42 is a cross rail, 43 is a negative pressure generation region, 44
Indicates magnetic heads.

Claims (1)

[Claims] 1. A negative pressure slider which has a magnetic head therein and draws the magnetic head to a predetermined height on a disk-shaped recording medium by negative pressure, and a gimbal which supports the negative pressure slider at one end.
A magnetic head moving device including a head arm for fixing the other end of the gimbal, an actuator for moving the head arm, and a control circuit for driving the actuator to bring the magnetic head to a predetermined position on a disk-shaped recording medium. In the method of (1), a means for vibrating the actuator in the seek direction near the natural frequency of the slider and gimbal system is provided, and the initial height of the negative pressure slider on the recording medium is set larger than the pull-in height. A magnetic head loading system, characterized in that the slider and gimbal system are resonated to load the magnetic head to the pull-in height by operating the means when the recording medium reaches a predetermined number of revolutions.