JPH04132051A - Supporting structure for head actuator for disk file device - Google Patents

Abstract

PURPOSE:To prevent an off-track accident by supporting a carriage on a rotation supporting shaft by a radial ball bearing, and fixing ferromagnetic material to a driving coil opposite to a permanent magnet, and giving pre-load in a radial direction to the ball bearing by magnetic attractive force between the permanent magnet and the ferromagnetic material. CONSTITUTION:The carriage 8 is fitted to the rotation supporting shaft 9 by two running-fitted upper and lower ball bearings 10, 11. The plate 17 of the ferromagnetic material is stuck and fixed to the vertical winding part of the coil 13 opposite to the permanent magnet 14 fixed to the surface of one side of the inner wall of a gap. Through this constitution, since the ferromagnetic plate 17 is always attracted by the permanent magnet 14 opposite to it, the coil 13, in its turn, the carriage 8 is pressed against the rotation supporting shaft 9 in its radial direction, and the bearings 10, 11 are given the pre-load. Thus, since thermal distortion to be caused in the bearing housing of the carriage 8 by thermal expansion can be suppressed small beforehand, the off-track accident is reduced.

Description

[Detailed Description of the Invention] [Summary] A carriage of a disk file device having a moving coil type driving means, regarding a support structure for a swing-type rad actuator of a magnetic disk device or an optical disk device used in an external storage device of a computer. The aim is to provide a simple structure for applying a radial preload to the bearing in the support structure of The disk is configured such that a magnet is fixed and a winding portion of the drive coil parallel to the rotational axis of the carriage receives a driving force by interlinking with a radial magnetic flux generated from a magnetic circuit made of the permanent magnet. In the Herad actuator for a file device, the carriage is supported on the rotating support shaft by a radial ball bearing, a ferromagnetic material is fixed to the drive coil facing the permanent magnet, and the permanent magnet and the ferromagnetic material are fixed to the drive coil facing the permanent magnet. The structure is such that a preload in the radial direction is applied to the ball bearing by the magnetic attraction force between the ball bearing and the body.

[Industrial application field]

The present invention relates to a support structure for a swing type rad actuator of a magnetic disk device or an optical disk device used in an external storage device of a computer.

[Conventional technology]

As shown in FIGS. 4(a) and 4(b), the disk file device consists of a disk l attached via a hub 3 to a spindle 2 that can rotate at high speed, and a head actuator. It consists of a carriage 8 that can swing around an axis 9 parallel to the spindle 2, and a drive means that swings the carriage 8.

An arm 7 holding a support 6 having a head 5 mounted on its tip is fixed to the carriage 8, and as the carriage 8 swings, the head 5 is moved in the radial direction along the surface of the disk 1, and the head 5 is moved radially along the surface of the disk 1. 5 at a desired address on the disk to read and write data.

The carriage 8 has two upper and lower radial bearings lO, 11.
It is rotatably supported by At least one of the bearings has its inner ring or outer ring not fixed, and is axially preloaded by a spring 12, thereby absorbing the internal gap of the bearing and allowing smooth rotation.

FIG. 3 shows an example in which a movable coil type carriage driving means is adopted, and a driving coil 13 is fixed to the continuous part of the carriage 8, while a magnetic circuit consisting of a permanent magnet 14 and a yoke 15 is installed on the frame side. Fixed. With this configuration, the coil 13 receives a driving force by passing a current through the magnetic flux generated by the magnetic circuit in the gap 16 of the magnetic circuit, and causes the arm 7 to rotate about the shaft 9. let

Normally, a magnetic disk drive equipped with a large number of disks has a dedicated servo head in addition to data heads corresponding to each disk surface, which reads servo information written on a specific disk surface. Another data head is positioned relative to the disk. Since these heads are mounted on the same carriage, for example, if the carriage expands due to heat generation during operation of the device, this will cause a change in the relative position of the servo head and the data head. Measures are required to prevent accidents (off-track) in which information cannot be read.

Furthermore, as mentioned above, in order to eliminate the axial clearance of the bearing, define the height of the carriage, and increase the axial rigidity of the carriage, it is necessary to apply axial preload to the bearing by the spring 12 or the like. be. Therefore, at least the fitting of the bearing that is displaced by receiving this preload is, for example, the fifth
As shown in Figure (a), it is a clearance fit (in this case, a clearance is provided between the inner ring of the upper bearing 10 and the shaft 9).

However, as it is, the radial position of the loosely fitted bearing 10 cannot be determined, so the inner ring is pressed against one side of the shaft 9 using a spring 19 or the like as shown in FIG. 5(b). .

Even in this case, the outer rings of both bearings 10 and 11 are connected to the carriage 8.
It is fixed to the housing by interference fit, adhesive, etc. In general, light alloys such as aluminum alloys and magnesium alloys are often used for the material of the carriage 8 in order to make it into a device.On the other hand, the bearings require rigidity and wear resistance, so fi (bearing steel) is used. There is a large difference in coefficient of thermal expansion between the two. Therefore, distortion is likely to occur in this portion due to temperature changes.

As one measure to solve this problem, as shown in Fig. 5(c), the inner rings of both the upper and lower bearings 10 and 11 are fixed to the steel shaft 9, and the outer ring is fitted with a clearance fit to the shaft. Applying preload in the direction is practiced. In this case, axis 9
Since the bearing inner ring and the bearing inner ring are made of the same material, the problem of distortion due to differences in thermal expansion is resolved. However, the upper and lower bearings 1
It is necessary to take measures to eliminate the play in the radial direction on the outer rings of Nos. 0 and 11. However, for boat fishing, it is difficult to attach the preload spring 20 to the bearing bousing portion of the carriage 8 because the body pressure cannot be maintained very large.

[Problem to be solved by the invention]

Still another method is to apply preload to the entire movable part in the radial direction relative to the fixed part, as shown in FIG. 5(d). In this case, radial preload is also applied to the bearing, and an improvement in radial rigidity can be expected. but,
Since the movable part and the fixed part cannot be directly connected by a spring, it is difficult to realize this in the case of a moving coil type driving means as shown in FIG.

The present invention solves the problems of the prior art and provides a simple structure for applying radial preload to a bearing in a carriage support structure of a disk file device having a moving coil type drive means. The purpose is to provide.

[Means to solve the problem]

For this purpose, a drive coil is fixed to the tail part of the carriage, while a permanent magnet is correspondingly fixed to the stationary part, and the winding part of the drive coil parallel to the rotation axis of the carriage is In a rad actuator for a disk file device configured to receive a driving force by interlinking with a radial magnetic flux generated from a magnetic circuit consisting of a permanent magnet, the carriage is mounted on the rotation support shaft by a radial ball bearing. A ferromagnetic material is fixed to the drive coil that supports the permanent magnet and faces the permanent magnet, and a radial preload is applied to the ball bearing by magnetic attraction between the permanent magnet and the ferromagnetic material. This is achieved by a head actuator support structure characterized by:

[Effect]

Since a ferromagnetic material facing the permanent magnet that constitutes the magnetic circuit is fixed to the drive coil fixed to the tail of the carriage, a magnetic attraction force always acts between the two, and the carriage moves in the radial direction with respect to the rotation axis. Towed by. This applies radial preload to the ball bearing, absorbing any play between the ball bearing inner ring and the rotating support shaft, or between the ball bearing outer ring and the bearing housing, ensuring smooth rotation. Ru.

Hereinafter, the present invention will be explained in more detail based on preferred embodiments shown in the drawings.

〔Example〕

FIG. 1(a) is a sectional view of a main part of a support structure for a head actuator according to a first embodiment of the present invention, and FIG. 1(b) is a plan view.

This support structure, like the conventional example shown in FIG. 3, relates to an actuator included in a moving coil type driving means.

A drive coil 13 fixed to the tail of the carriage 8 has an inner arc-shaped cross section and is movable along a sector-shaped gap 16 of a yoke 15 fixed to the frame. On the other hand, plate-shaped permanent magnets 14 are fixed to both opposing inner wall surfaces of the air gap 16 to generate magnetic flux that crosses the air gap. When a current is passed through the coil 13, the coil 1
Since a force perpendicular to the direction of the magnetic flux is applied to 3, the carriage 8 is rotated about the rotation support shaft 9.

As a result, a magnetic head (not shown) carried by the carriage 8 can be moved to any radial position on the disk.

As shown in FIG. 5(d), the carriage 8 is mounted on a rotational support shaft 9 by two upper and lower ball bearings 10 and 11 that are fitted with clearance.
In Figure 0, the reference numeral 12 indicates a spring for applying axial preload to the bearing.

The feature of the present invention is that, as shown in FIG. The point is that a plate 17 of ferromagnetic material such as ferromagnetic material is pasted and fixed. With this configuration, the ferromagnetic plate 1
Since the coil 13 is always attracted to the facing permanent magnet 14, the coil 13 and therefore the carriage 8 are pressed in the radial direction with respect to the rotational support shaft 9. Therefore, a preload in the radial direction is applied to the bearings 10.11, and play caused by the loose fit is absorbed.

In order to install the plate 17, the gap between the air gaps 16 needs to be wider than usual, and the overall air gap magnetic flux density decreases, but in the coil part where the plate 17 is attached, the plate functions as a yoke. In other words, the total amount of magnetic flux passing through the yoke 15 decreases with respect to the magnetic flux density of the coil portion, so the magnetic flux density increases more than that of other parts. A coil-type actuator with a long stroke has the advantage of making the yoke design easier.

As shown in FIG. 1, the ferromagnetic plate 17 is placed closer to the inner wall than the center plane of the air gap 16, causing an imbalance in the magnetic flux distribution on both sides, and It is strongly attracted and generates effective radial preload.

This plate 17 also functions as a structural member, and the coil 13
The stiffness can be increased.

Normally, magnetic materials such as electromagnetic soft iron are electrically good conductors, so there is a concern that eddy currents may be generated when they move in a magnetic circuit. By reducing the radius of rotation of the magnetic plate and keeping the speed in the tangential direction low, it is possible to reduce the generation of eddy currents to a level that does not cause problems. As a countermeasure against this problem, it is also effective to use a material with a high specific resistance such as silicon steel.

The ferromagnetic plate to be attached does not need to be attached to the entire gap 16, but may be applied to an area range that provides the desired radial preload.

FIG. 3 shows a second embodiment of the present invention, which differs from the first embodiment in that the magnetic plate 17 is fixed across the upper and lower surfaces of the carriage 8 with screws 18, and the coil 13 is The structure is such that it is bonded and fixed onto the plate 17. This increases overall stiffness and eases assembly. Note that in the case of the first embodiment and the case of the second embodiment, the magnetic attraction force acts in opposite directions with respect to the rotation support shaft 9, but the effect remains the same.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to apply a radial preload to the moving coil type head actuator of a disk file device, and the thermal distortion generated in the bearing housing of the carriage due to thermal expansion can be avoided. off-track accidents can be reduced.

As a result, it becomes possible to realize a device with a higher recording density in the track direction.

[Brief explanation of drawings]

Figure 1 (a) is a cross-sectional view of the main part of the first embodiment of the present invention, Figure 1 (b) is the same (plan view), Figure 2 is the coil of the first embodiment with a ferromagnetic plate attached. FIG. 3(a) is a sectional view of a main part of the second embodiment of the present invention, FIG. 3(b) is a plan view of the same, and FIG. 4(a) is a diagram of a conventional moving coil type Herad actuator. 4(b) is a plan view, and FIGS. 5(a) to 5(d) are schematic diagrams showing how to fit the bearing and apply preload. l...Magnetic disk 2-spindle Shaft 3 - Hub 5 - Head 5 7 - Arm 8 - Carriage 9 - Carriage rotation support shaft 10.11 - Radial ball bearing 12 - Preload spring 13 - Coil 14 - Permanent magnet 15 - Yoke 16. -Gap 17--Ferromagnetic plate 11!a (Q) 7...Arm 8...Carriage Main part plan view of the first embodiment of the present invention 1!1 (b) A cross-sectional view of the main parts of the second embodiment of the present invention Fig. 3 (Q) A plan view of the main parts of the second embodiment of the invention Fig. 3 (b) Gun view (Q) Inner ring clearance , without backlash b) Inner ring clearance, with inner ring backlash removed (C) Outer ring clearance, outer ring backlash removed Schematic diagram showing how to fit and apply preload to a bearing No. 51
1g

Claims (1)

[Claims] 1. A drive coil (13) is fixed to the tail of the carriage (8), and a permanent magnet (corresponding to this) is attached to the stationary part.
14) is fixed, and the winding portion of the drive coil (13) parallel to the rotational spindle (9) of the carriage interlinks with the radial magnetic flux generated from the magnetic circuit consisting of the permanent magnet (14). In the head actuator for a disk file device, the carriage (8) is supported on the rotating shaft (9) by radial ball bearings (10, 11), and the permanent magnet (14)
) The ferromagnetic material (17
) is fixed, and the permanent magnet (14) and the ferromagnetic body (1
7) Ball bearings (10, 11) by magnetic attraction between
A support structure for a head actuator, characterized in that a radial preload is applied to the head actuator.