JP2000315361A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable magnetic disk device in which a magnetic circuit is fixed by an elastic material, by providing a magnetic circuit supporting method capable of preventing the loss of impact resisting performance. SOLUTION: In a magnetic circuit supporting portion 12, an inner hub 14 is displaced integrally with a magnetic circuit 9. On the other hand, an outer hub 15 is fixed to a base 10 or a cover 11. At this time, a spacing between a yoke 7 and the outer hub 5 is set smaller than that between a magnet surface and its opposing coil surface. Thus, even when impacts are applied during the carrying of the device, the resonance peak of a carriage supporting system or a spindle supporting system is reduced and high positioning accuracy is secured without losing the performance of the coil or the magnetic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk for recording information on an information recording medium by holding a head on an information recording medium such as a magnetic disk or a magneto-optical disk, or for reading information from the information recording medium. More particularly, the present invention relates to a magnetic circuit fixing technique for a head positioning mechanism system using a voice coil type driving mechanism.

[0002]

2. Description of the Related Art To increase the recording density of a magnetic disk drive,
It is effective to reduce the positioning error of the write / read head on the disk and store the information in a narrower area. A moving coil type voice coil motor (VCM) is generally used as a driving method of a positioning operation of a magnetic head with respect to a magnetic disk surface.

The magnetic circuit serving as the stator of this VCM is:
For example, as described in Japanese Patent Application Laid-Open No. 5-336869, it is common to fix it to a housing with screws.

Further, as described in Japanese Patent Application Laid-Open No. 1-137476, there is also a configuration in which a driving reaction force generated in a magnetic circuit is fixed to a housing via a vibration damping material so as not to be transmitted to the housing. is there.

[0005]

The problem to be solved by the present invention is disclosed in Japanese Patent Application Laid-Open No. 1-137476.
By fixing the magnetic circuit via a vibration damping material as in the device described in Japanese Patent Application Laid-Open Publication No. H10-260, the resonance of the spindle support system on which the magnetic disk is mounted and the resonance peak of the carriage support system are reduced. Since such spindle resonance or carriage resonance becomes a limiting factor of the servo band of the positioning mechanism or becomes residual vibration when the head is moved from one track to another track, it is necessary to reduce the resonance peak. is there.

However, when the magnetic circuit is supported via the damping material, there are the following problems.

That is, in the case of such a structure, rubber is often used as a vibration damping material. The support rigidity of the magnetic circuit supported via the rubber in this way is not only in the in-plane direction but also in the out-of-plane direction. However, it is lower than that in the case of ordinary screw fixing. For this reason, there is a problem that the rubber is excessively deformed due to the inertial force generated in the magnetic circuit when receiving an impact during transportation or the like, and the magnet surface collides with the coil to damage the coil.

On the other hand, the clearance between the magnets cannot be widened in order to increase the magnetic flux density and secure the driving force of the actuator.

In view of this problem, the present invention provides a magnetic disk drive in which a magnetic circuit is fixed by an elastic body and a magnetic circuit supporting method that does not impair the shock resistance, thereby providing a highly reliable disk drive. The purpose is to:

[0010]

In order to achieve the above object, in the magnetic disk drive of the present invention, the magnetic circuit is supported as follows.

That is, in a magnetic disk drive in which the magnetic circuit supporting portion is made of an elastic material for displacing the magnetic circuit,
The distance between the housing and the side of the magnetic circuit facing the housing is made shorter than the distance between the coil and the magnet surface.

With this configuration, the side surface of the magnetic circuit comes into contact with the housing before the magnet surface collides with the coil, and further displacement of the magnetic circuit is prevented, so that the coil is not damaged.

[0013] Further, the magnetic circuit supporting portion is constituted by a movable portion fixed to the magnetic circuit, a fixed portion fixed to the housing, and a deformed portion connecting between them, so that the magnetic circuit becomes the fixed portion. The same action as described above is obtained by contact.

Further, if the clearance between the movable portion and the fixed portion is made smaller than the clearance between the coil and the magnet so that the movable portion comes into contact with the fixed portion at the time of impact, the same effect as described above can be obtained. In addition, the magnetic circuit does not directly hit the housing.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 is a top view of the inside of the magnetic disk drive according to the embodiment of the present invention when the top cover is opened. In this magnetic disk drive, the head 3 is positioned on a track on the disk 4 by rotating the carriage 1 around the pivot shaft 2. The driving force of the carriage is obtained by applying a current to the coil 5 in a magnetic field generated by a permanent magnet 6 provided so as to sandwich the coil 5 attached to the carriage.

FIG. 1 shows the magnetic disk drive shown in FIG.
FIG. 2 is a side sectional view showing a structure and an attached state of a magnetic circuit. The permanent magnet 6 is bonded to a yoke 7 made of a metal having high magnetic permeability. The upper and lower yokes are also connected via a column 8 having high magnetic permeability, so that the magnetic field generated by the magnet 6 is closed. This magnet 6 and yoke 7
The structure including the support 8 and the support 8 is referred to as a magnetic circuit 9 here. The magnetic circuit 9 includes a base 10 and a cover 11 (which are collectively referred to as a housing).
Supported by

FIG. 2 shows the details of the magnetic circuit support section 12.
The magnetic circuit supporting portion 12 includes an inner hub 14, an outer hub 15, and a rubber 16 filled therebetween. Inner hub 14 is screw 17
And the outer hub 15 is adhered to the base 10 or the cover 11.

The advantage of supporting the magnetic circuit 9 via a viscoelastic material such as rubber instead of directly fixing it to the housing is as follows.

In general, the lowest-order mechanism resonance frequency for positioning the head on the track, excluding rigid rotation about the pivot axis of the positioning mechanism system, is resonance in the translation direction in the in-plane direction of the carriage. This is a vibration component such that the carriage 1 corresponding to the mass vibrates by a spring having a spring constant equal to the rigidity of the pivot shaft 2 and the bearing supporting the carriage 1. If the peak gain of this vibration component is high, the stability of the positioning control system may be impaired or residual vibration may occur during the positioning operation.

Here, by supporting the magnetic circuit 9 via a viscoelastic body, the vibration system composed of the magnetic circuit 9 and the support portion 12 is operated as a dynamic vibration absorber for the carriage vibration system, so that the peak gain of carriage resonance is obtained. To reduce. As a result, the stability of the positioning control system is improved, the positioning accuracy is improved, and the density of the magnetic disk drive is increased. Further, the occurrence of residual vibration is suppressed to reduce the time required for the head to move between tracks, thereby enabling high-speed transfer.

Further, if rubber is used, since the support attenuation is ensured, the gain of the carriage vibration is further reduced. Preferably, the rigidity of the magnetic circuit support system 12 is determined so that the in-plane natural frequency of the magnetic circuit support system and the resonance frequency of the carriage are substantially equal, and thereby the shape and size of the rubber 16 are determined. However, even in such a case, it is effective because a part of the driving reaction force generated in the magnetic circuit can be attenuated.

In the structure shown in FIG.
In 2, the inner hub 14 is displaced integrally with the magnetic circuit 9.
On the other hand, the outer hub 15 is fixed to the base 10 or the cover 11.

At this time, as shown in FIG. 1, the distance A between the yoke 7 and the outer hub 15 is set to be smaller than the distance B between the magnet surface and the coil surface opposed thereto (A <B).
The method of determining the detailed dimensions will be described later.

Here, let us consider a case where an impact acts during transportation of the present apparatus. In particular, when a vertical shock is applied to the magnetic disk main body, the magnetic circuit is vertically displaced by the inertial force generated in the magnetic circuit 9.

FIG. 3 is a view showing a state where the magnetic circuit is displaced in the direction C in the figure. Since A <B as described above, the magnetic circuit 9 is displaced until the yoke 7 hits the outer hub. However, even in this state, the gap is maintained between the coil 5 and the lower magnet, 5 does not collide with the magnetic circuit.

On the other hand, FIG. 4 shows a case where A> B, which is a configuration outside the scope of the present invention. As described above, the coil 5 collides with the magnet 6 first, and the supporting state of the coil 5 is changed. Therefore, the required driving force cannot be obtained, and the performance is deteriorated.

The procedure for determining the clearance A or B will be described.

The allowable impact force specified in the specification of the magnetic disk drive is the same as the failure at other parts,
Consider whether a collision between the magnetic circuit 9 and the coil 5 occurs.

Here, it can be considered that the deformation of the magnetic circuit 9 itself when the impact is applied is sufficiently small. Further, the amount of deformation of the coil bobbin 13 supporting the coil 5 with respect to the allowable impact force is obtained in advance.

On the other hand, the clearance B between the coil 5 and the magnet 6 in a state where no impact is applied (FIG. 1) is determined in advance from the performance such as the magnetic flux density of the magnet, the assembly tolerance of the coil and the magnetic circuit, and the manufacturing restrictions. I have. Clearance B when no impact is applied
From the above and the above-described coil deformation amount, the residual clearance in a state where an impact is applied can be obtained.

From the remaining clearance, the magnetic circuit 9 and the outer hub 1
The clearance A is determined so that the clearance A with 5 becomes small. By doing so, the amount of displacement of the magnetic circuit 9 due to the impact force does not become B or more, so that the gap shown in FIG. 3 is left by the difference between the residual clearance and the displacement A of the magnetic circuit 9 at the time of impact. Become.

Since the same discussion can be made for the case where the impact direction is opposite, it is desirable that the clearance between the coil surface and the magnet surface be the same for the upper and lower surfaces of the coil.

In practice, it is necessary to take into account the coil assembly tolerance and the mounting tolerance to the base 10. In the above configuration, the upper limit value or the lower limit value of each tolerance is added, and it is assumed that the coil surface and the magnet surface are closest to each other, and the dimension A is made smaller than the dimension B at this time.

FIG. 5 is a side sectional view showing details of a magnetic circuit supporting portion according to a second embodiment of the present invention.

The structure of the magnetic circuit supporting portion 12 is the same as that of the first embodiment, except that a projection surface 17 is provided on the cover 11 or the base 10, and the magnetic circuit 9 first strikes the projection surface 17 when an impact is applied. , The displacement is limited, so that the same effect as described above can be obtained. That is, the projection surface 17
The distance between the yoke 7 and the surface of the yoke 7 corresponds to the above dimension A. With such a configuration, the base 10 or the cover 11
, The area of the projecting surface 17 can be increased, and the contact portion of the magnetic circuit 9 with the yoke 7 can be increased, so that the surface pressure at the time of collision can be reduced. is there.

FIG. 6 is a side sectional view showing details of a magnetic circuit supporting portion according to a third embodiment of the present invention.

In this embodiment, the flanges 18 and 19 are attached to the inner hub 14 and the outer hub 15, respectively, so that the inner hub 14 of the magnetic circuit support 12 is displaced together with the magnetic circuit 9 so that the inner hub 14 can directly contact the outer hub 15. Provide. And inner hub 1
First, a clearance A is defined in this portion so that the flange 18 of the fourth and the flange 19 of the outer hub 15 collide. Further, the distance between the yoke surface of the magnetic circuit 9 and the outer hub 15 is set to be longer than that. In this case, the same effects as those of the above embodiments can be obtained. Furthermore, this has the advantage that the yoke 7 does not directly hit the outer hub or the cover / base.

The embodiment according to the present invention has been described with reference to the drawings. In any of the embodiments, the resonance peak of the carriage support system or the spindle support system can be reduced without impairing the performance of the coil and the magnetic circuit even when an impact is applied during the transportation of the apparatus, and the like. Positioning accuracy can be ensured.

In the description of each of the above embodiments, the vertical direction refers to a direction perpendicular to the disk surface of the magnetic disk device. Similarly, an in-plane direction or an out-of-plane direction is defined for a plane parallel to the disk surface. The out-of-plane direction and the up-down direction are the same.

[0041]

According to the present invention, the resonance peak of the carriage support system and the spindle support system can be reduced.
It is possible to improve the positioning accuracy by expanding the servo band of the positioning mechanism system, and to reduce the residual vibration due to the resonance during the head positioning operation, thereby enabling high-speed positioning.

Further, even when a shock is applied, there is an effect that the coil is not damaged by restraining the displacement of the magnetic circuit.

As a result, a high-speed, large-capacity magnetic disk drive with high reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a detailed side view of a magnetic circuit and a support portion according to a first embodiment of the present invention.

FIG. 2 is a detailed view of a magnetic circuit support according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an operation state when a shock is applied according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an operation state when an impact is applied in an example outside the scope of the present invention.

FIG. 5 is a detailed side view of a magnetic circuit and a support according to a second embodiment of the present invention.

FIG. 6 is a detailed side view of a magnetic circuit support according to a third embodiment of the present invention.

FIG. 7 is an internal top view of the magnetic disk drive using the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Carriage, 2 ... Pivot axis, 3 ... Head slider, 5 ... Coil, 6 ... Permanent magnet, 7 ... Yoke, 8 ... Prop, 9 ... Magnetic circuit, 10 ... Base, 11 ... Cover, 12
... magnetic circuit support, 13 ... coil bobbin, 14 ... inner hub, 15 ... outer hub, 16 ... rubber, 17 ... protrusion, 18 ...
Inner hub flange, 19 ... outer hub flange.

Claims (4)

[Claims] A carriage for supporting a magnetic head for writing and reading information to and from a magnetic disk so as to be movable in a substantially radial direction of the magnetic disk; a coil fixed to the carriage for driving the carriage; A magnetic disk drive comprising: a magnetic circuit for providing a driving force to the carriage in pairs with a coil; a housing containing the magnetic disk, the carriage, and the magnetic circuit; and a magnetic circuit supporter for supporting the magnetic circuit on the housing. In the above, the magnetic circuit support portion includes a movable portion fixed to a magnetic circuit, a fixed portion fixed to a housing, and a deformed portion connecting between the movable portion, the movable portion being displaced together with the magnetic circuit, A gap between the magnet surface of the magnetic circuit and the coil in a state of contact with the magnetic disk. A carriage for supporting a magnetic head for writing and reading information to and from the magnetic disk so as to be movable in a substantially radial direction of the magnetic disk; a coil fixed to the carriage for driving the carriage; A magnetic disk drive comprising: a magnetic circuit for providing a driving force to the carriage in pairs with a coil; a housing containing the magnetic disk, the carriage, and the magnetic circuit; and a magnetic circuit supporter for supporting the magnetic circuit on the housing. In the above, the magnetic circuit support portion is composed of a movable portion fixed to the magnetic circuit, a fixed portion fixed to the housing, and a deformed portion connecting the fixed portion and the magnetic circuit displaced and contacted the fixed portion. A magnetic disk drive, wherein there is a clearance between a magnet surface of a magnetic circuit and the coil in a state. 3. A carriage for supporting a magnetic head for writing and reading information on and from a magnetic disk so as to be movable in a substantially radial direction of the magnetic disk, a coil fixed to the carriage and driving the carriage, and A magnetic disk drive comprising: a magnetic circuit for providing a driving force to the carriage in pairs with a coil; a housing containing the magnetic disk, the carriage, and the magnetic circuit; and a magnetic circuit supporter for supporting the magnetic circuit on the housing. In the above, the magnetic circuit supporting portion has a deformable portion capable of displacing the magnetic circuit in a direction perpendicular to the magnet working surface, and the distance between the side of the magnetic circuit facing the base or cover and the base or cover. Is shorter than the distance between the coil surface and the magnet working surface. 4. The method according to claim 1, wherein
A magnetic disk drive, wherein the deformable portion is a viscoelastic body.