JPS6314374A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To start smooth magnetic head floating while the magnetic disk is driven by giving a waveform increasing periodically on a time base to a current waveform given to the coil of a DC motor at the start of the DC motor and increasing the maximum current of the waveform stepwise with time. CONSTITUTION:The current waveform given to the coil of the DC motor 5 at start is that a triangle wave continues intermittently, the level of each triangle wave is increased sequentially as I1, I2... and the level reaches the maximum current Imax finally. That is, the current waveform given to the coil is increased periodically on the time base and increased stepwise with the lapse of time. Thus, in starting the DC motor 5, the DC motor 5 is driven by a required minimum start torque to drive a magnetic disk 1, and the motor repeats the operation that the motor goes to stop once and then is started soon, then the current reaches the maximum current Imax soon and the steady-state revolution is reached. Thus, even though the contact of the magnetic head 2 is taken place, the magnetic head 2 is separated smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk device that takes into account the entire waveform of a current flowing through a DC motor that rotates a magnetic disk at startup.

(Prior Art) In a conventional magnetic disk drive equipped with a DC motor, the 'tL current waveform applied to the coil of the DC motor when starting up the magnetic disk generally has a triangular waveform as shown in FIG. A constant maximum current Imax is allowed to flow.

When the magnetic disk drive is in a normal state, such 'I! It is sufficient to start a DC motor using a current waveform and there is no problem.

However, as the performance of magnetic disk devices has improved in recent years, the smoothness of the magnetic disk surface has improved, and the so-called dense layer phenomenon of magnetic heads has become noticeable.

This adhesion phenomenon means that while the magnetic disk is stopped, the magnetic head is tightly layered on the surface of the magnetic disk, and the starting torque of the magnetic disk increases abnormally. The adhesion phenomenon is largely influenced by the surface precision of the magnetic head and the magnetic disk, as well as the adsorbed substances on the surface, and in particular, the adhesion state has viscous properties. That is, when an attempt is made to separate the two parts that are in close contact with each other, the two parts exhibit adhesive behavior, during which force is generated that deforms the other elastic components.

(Problems to be Solved by the Invention) In the conventional magnetic disk drive described above, the current waveform flowing to the DC motor at the time of startup has a triangular plate shape, and increases up to the maximum current Imax. A large starting torque is generated instantaneously when the motor rotates.

In this case, as mentioned above, when the magnetic heads adhere to each other in the magnetic disk drive, a force is generated that pulls the magnetic heads 1 that are in close contact with each other, causing the gimbals and other components that make up the entire magnetic head to peel off. It will lead to destruction. Furthermore, these destructions cause functional loss of the magnetic head9, leading to a fatal failure of the magnetic disk device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic disk device that avoids applying a sudden overload even when a magnetic head is in close contact with the magnetic head, and allows smooth separation of the magnetic head.

(Means for Solving the Problems) In order to achieve all of the above objects, a magnetic disk device according to the present invention includes a plurality of magnetic disks and a contact start/stop type magnetic head arranged on the surface of the magnetic disks in a housing. In a magnetic disk drive that drives the magnetic disk by directly connecting a DC motor to a rotary machine groove in which all of the magnetic disks are stacked, a current waveform flowing through the coil of the DC motor at the start of the DC motor is expressed as a time axis. The waveform is configured to increase periodically at the top, and the waveform is configured to increase stepwise with the maximum time of the waveform.

(Example) The invention below with reference to the drawings? I will explain in more detail.

FIG. 2 is a diagram illustrating an example of a magnetic disk device according to the present invention, and is shown in the waveform of the current flowing through the coil of the direct light motor at the time of starting.

The triangular wave shape continues intermittently, and the height of each triangular waveform sequentially increases to I+, I2, and so on. I3... it becomes thicker,
This is the waveform that finally reaches the maximum current Imax.

In the embodiment, an example of an intermittent triangular waveform is shown as the waveform, but it is needless to say that the same effect can be obtained if the waveform is not limited to the female waveform but periodically increases.

(Effects of the Invention) As explained in detail above, in the magnetic disk device according to the present invention, the current waveform flowing through the coil increases periodically on the time axis and increases stepwise with time, so when starting the DC motor, The DC motor rotates for the first time with the minimum starting torque required to drive the magnetic disk, then stops and then stands up again.By repeating this process nine times, the maximum current Imax is eventually reached. , and the rotational speed reaches a steady state.

Therefore, it is possible to avoid suddenly applying an excessive load even when the above-mentioned adhesion phenomenon of the magnetic head occurs, and the magnetic head can be smoothly moved. i! enable. That is, according to the present invention, the magnetic disk does not rise suddenly as in the conventional case, but gradually rises.

In addition, once the magnetic head and the magnetic disk come to a stop, a force in the opposite direction to the normal rotational direction is applied between the magnetic head and the magnetic disk due to the effect of the magnetic head's elastic components, such as gimbal springs. It also has the effect of softening the viscous force. As described above, according to the present invention, it is possible to obtain the effect of enabling the magnetic head to start flying smoothly when the magnetic disk rotates.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an entire embodiment of a magnetic disk drive according to the present invention, and FIG. 2 is a vertical sectional view showing an entire embodiment of a magnetic disk drive according to the present invention. Diagram showing an example of a single stream with a ryudum shape, No. 3
The figure shows the waveform of the current flowing to the coil of the motor during rotation of the magnetic disk in a conventional magnetic disk loading system. 1...Magnetic disk 2...Magnetic head 3...
・Housing 4...Rotating mechanism part 5...DC motor E...Current I max...Maximum 1! Kentoki Ifl11 Applicant NEC Co., Ltd. Agent Patent Attorney Hisashi Inoro 21 Figures 2 Figures 23

Claims (1)

[Claims] A plurality of magnetic disks and a contact start/stop type magnetic head arranged on the surface of the magnetic disks are housed in a housing, and a DC motor is directly connected to a rotating mechanism unit that stacks the magnetic disks to drive the magnetic disks. In the magnetic disk drive, when the DC motor is started, the waveform of the current flowing through the coil of the DC motor is set to a waveform that increases periodically on the time axis, and the maximum current of the waveform is increased stepwise with time. A magnetic disk device characterized in that it is configured as follows.